Outstanding formaldehyde abatement performance and preferable resistance to SO 2 and H 2 O over CrO x -CeO x facilitated hierarchical porous biochars catalysts

Outstanding formaldehyde abatement performance and preferable resistance to SO 2 and H 2 O over CrO x -CeO x facilitated hierarchical porous biochars catalysts | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Outstanding formaldehyde abatement performance and preferable resistance to SO 2 and H 2 O over CrO x -CeO x facilitated hierarchical porous biochars catalysts Yun Jiang, Xiaoxin Feng, Lei Gao, Jiangyong Dai, Dong Xie, Caiting Li, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5297317/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract A suite of CrCe oxides facilitated hierarchical porous biochars from walnut husks and rice straws (XCryCe1-y/WSAC) were readily synthesized for formaldehyde (HCHO) abatement. BET, XRD, XPS, SEM, H2-TPR, TG-DTG, and in situ DRIFTS were adopted to disclose their physicochemical properties and the elimination mechanism of HCHO. 18%Cr0.5Ce0.5/WSAC exhibited splendid HCHO abatement efficiency (99.2%) at 280°C. The effects of O2, SO2, H2O for HCHO abatement over 18%Cr0.5Ce0.5/WSAC were trialed, and the strangulation influences of SO2 counteracted the furtherance effect of O2 to some extent, which was relieved by the facilitation of H2O. CrOx-CeOx co-facilitated WSAC presented better performance than Cr or Ce oxide separately facilitated WSACs, which was associated with the redox cycle of Cr6++Ce3+↔Cr3++Ce4+, resulting in higher redox capability, better dispersion of active ingredient, more oxygen vacancies and superior active oxygen mobility. Furthermore, the hierarchical porous support accelerated the diffusion and mass transfer of reactants and intermediates. Noteworthily, the effects of CrOx-CeOx and the hierarchical porous structure of the support on the tolerance to SO2 and H2O were deeply and systematically investigated. Ultimately, 18%Cr0.5Ce0.5/WSAC emerged desirable prospects in practical applications thanks to splendid catalytic performance and satisfactory resistance to SO2 and H2O. Earth and environmental sciences/Environmental sciences Physical sciences/Chemistry Physical sciences/Materials science hierarchical porous biochar catalytic oxidation formaldehyde SO2 resistance Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 1. Introduction Volatile organic compounds (VOCs) have sparked enormous attention worldwide due to their marked quantities and undesirable effects on the environment and human health 1 . As one of frequently encountered VOCs, HCHO was widely recognized as a potential threat in view of its grievous toxicity, carcinogenicity and teratogenicity 2 . To respond to these increasing environmental consciousness and rigorous emission regulations, multitudinous technologies for lessening HCHO emissions have been exploited, such as photocatalytic degradation, adsorption, biofiltration, condensation, plasma technology, and catalytic oxidation 3-6 . Among which, catalytic oxidation is considered to be a promising and resultful strategy to treat VOCs pollution on account of its unobjectionable cost, gratifying reliability and efficiency 7,8 . It is universally acknowledged that catalysts are the core factor in catalytic oxidation reactions. Among which mainstream catalysts are mainly divided into two types: supported precious metal catalysts and supported transition metal oxide catalysts 9 . Thereinto, diverse metal oxide supports such as CeO 2 10 , TiO 2 11 , Al 2 O 3 12 , MnO 2 , SiO 2 13 and their composites including CeO 2 -TiO 2 14 , InO 3 -SnO 2 , MnO x -CeO 2 and CoO x -CeO 2 15 are popularly investigated for VOCs abatement inasmuch as their fine redox performance, outstanding dispersion, and the synergy effect between such supports and active metal oxides. Nevertheless, their widespread applications are impeded due to several defects like relatively expensive price, heterogeneous structure, low specific surface area, uncontrollable shape and size 16,17 . Equally, activated carbon is recognized as the most extensively adopted support of catalysts for VOCs abatement on account of its tunable price size, larger surface area, lower price, flexible application conditions and high hydrophobicity 1, 18 . However, the pore structure of conventional coal-based activated carbon possessed most micropores as well as slight mesopores and macropores, which led to the unsatisfactory adsorption and catalytic behaviors for VOCs abatement by its inconvenient internal diffusion and mass transfer 19 . In particular, the micropores of activated carbon might be chiefly semi-closed and bring trouble to the desorption of reactants and products 20 . Fortunately, differentiated from aforesaid commercial activated carbon, emerging hierarchical porous biochars were not mainly composed of micropores but a certain percentage of mesoporores and macropores, which greatly retrofitted the adsorption and catalytic performance for VOCs abatement through facilitating internal diffusion and mass transfer 21 . Meanwhile, lavish micropores greatly amplified the specific surface area, thus improving the adsorption capacity of small molecular gases, whereas mesopores and macropores could be employed as capacious rooms for active ingredients dispersion, providing channels for the transfer and mass diffusion 22,23 . In addition, mesopores and macropores could partly avoid SO 2 contaminating active ingredients 24 . Therefore, a new type of cheap and efficient hierarchical porous biochars possessed a great potential in the field of catalysis for VOCs abatement. However, the abatement capacity of biochars toward VOCs is also restricted by its finite physicochemical property like finite activated sites 25 . According to reports, carbon-based materials loaded with metal oxides exhibited both higher adsorption and catalytic ability 1 . Therefore, biochars modified with metal oxides seem to be a potential and efficacious approach for improving their activity to a great extent 26 . As previously reported, some precious metal catalysts (Pt, Pd, Au, Rh, Ag, etc.) are tempting by their excellent activity for VOCs abatement, but they are commonly expensive and easily inactivated by poisoning or sintering 1,4 . On the contrary, transition metals have been extensively researched for their superior catalytic activity, readily availability, and low cost 27,28 . Thereinto, CeO x has attracted much publicity in catalysts for VOCs elimination by reason of abundant active oxygen species, high oxygen storage and release capacity, ample oxygen vacancies, and polyvalent transition 29,30 . Nevertheless, cerium-based catalysts were prone to suffer from SO 2 poisoning 31,32 . Universally acknowledged, the adulteration of CeO x with other metal oxides such as MoO x could produce synergistic effect, which was conducive to promoting VOCs oxidation and SO 2 tolerance 32-34 . As a kind of metal promoter and stabilizer, CrO x might exhibit preeminent catalytic activity as well as splendid SO 2 resistance in VOCs oxidation reactions 35-37 . It was demonstrated that CrO x could reduce the adsorption energy of SO 2 on the stable adsorption site of main active phases, thereby improving the SO 2 resistance of the catalyst 38 . Liu et al. found CeO 2 -TiO 2 doped with Cr catalysts behaved excellent SO 2 tolerance. Due to the synergistic effect of high oxygen storage-release Ce and Cr species, CrO x -CeO 2 /MO y catalyst (M = Ti, V, Nb, Mo, W and La) had been reported to yield superior performance for Cl-VOCs oxidation 39 . Thus, it is sensible to extrapolate that CrO x -CeO x facilitated hierarchical porous biochar catalysts might manifest satisfactory performance for VOCs abatement and SO 2 resistance. To the best of our understanding, few studies have focused on CrO x -CeO x modifed biochars for HCHO abatement, in which the synergistic effect between CrO x and CeO x might contribute to the enhancement of catalytic performance and resistance to SO 2 and H 2 O. Therefore, a series of tests are conducted to investigate the role of CrO x -CeO x facilitated hierarchical porous biochar catalysts on the performance and resistance to SO 2 and H 2 O for HCHO abatement in this work. A crowd of analytic techniques such as BET, XRD, XPS, SEM, H 2 -TPR, TG-DTG, and in situ DRIFTS were performed to uncover the structure-activity relationship of CrO x -CeO x modifed biochars catalysts and their elimination mechanism of HCHO. 2. Materials and Methods 2.1. Samples preparation Walnuthusksand rice straws as biochar precursors were respectively gathered in Aksu City, Xinjiang Province, and Hengyang City, Hunan Province, China. Various biochars derived from individual walnut shell, separate solitary rice straw, and their union were defined as WAC, SAC, and WSAC, respectively. Firstly, the raw materials were rinsed with deionized water, then dried overnight at 105 °C, and screened for standby application after repeatedly dried-crushed to powder. The treated raw materials were activated through ZnCl 2 solution and then carbonized in a 700 °C electronic tube furnace under N 2 protection. The resulting powder was cooled and washed with deion water every 20 min for more than 50 times, and dried under a constant temperature drying box for 24 hours. In addition, Ce(NO 3 ) 3 •6H 2 O and Cr(NO 3 ) 3 •9H 2 O worked as the active ingredient precursors of CeO x and CrO x , respectively. Suitable WSAC was impregnated into the solution of active ingredient precursors for 24h. After impregnation, the samples were dried in a 60 °C drying chamber for 48h and calcined in the N 2 atmosphere in a 450 °C electronic tube furnace for 5h. The ultimately acquired samples were labeled as XCr y Ce 1-y /WSAC, in which y indicated the proportion of Cr in CrO x -CeO 2 , and1-y delegated the proportion of Ce in CrO x -CeO 2 ,while X represented the total mass percentage of the metal oxides in the sample. Simultaneously, the individual Cr/WSAC and Ce/WSAC as well as WAC, SAC, and WSAC were also manufactured using the identical method for comparison. 2.2. Samples characterization The parameters of pore structure and BET surface area involved the samples were estimated through the micromeritics ASAP2460 specific surface and porosity analyzer (McMeretic Instruments, Shanghai). The surface structures and morphologies of specimens were scanned on electron microscopy (SEM) photographs, and then were analyzed on the MIRA4 analyzer (TESCAN, Czech Republic). The X-ray diffraction (XRD) results were gathered through a BRUKER D8 Advance (Bruker, Germany) X-ray diffraction device with the purpose of making a thorough inquiry into the dispersivity and component crystallinity of the samples. The H 2 -temperature programmed reduction (H 2 -TPR) was in progress by employing the Tianjin Xianquan TP-5080 automatic chemical adsorption instrument to emerge the redox behavior of specimens. The K-Alpha 250XI X-ray photoelectron spectrometer (America Thermo, USA) was applied to analyze the chemical properties and element chemical constituents of samples. The thermogravimetric (TG) analysis was carried out by employing a NETZSCH Thermal Analyzer (Germany) with a heating rate of 10 °C/min for investigating the sulfur resistance and thermal stability of fresh 18%Ce/WSAC, fresh 18%Cr 0.5 Ce 0.5 /WSAC, used 18%Ce/WSAC, and used 18%Cr 0.5 Ce 0.5 /WSAC. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of samples was collected on a Nicolet iz10 (Thermo Fisher, USA). 2.3 . Experimental design and operation As emerged in Fig.1, the test device of the specimens purging HCHO principally consisted of three sections: a gas analyzer system, a simulated flue gas system, and a continuous flow fixed bed reactor system. The simulated flue gas (SFG) normally contained 200 ppm HCHO, 6%O 2 , and approximately 94%N 2 . The liquid HCHO was injected into the polytetrafluoroethylene tube wrapped by the temperature-dominated heating belt through a peristaltic pump and was heated to form a high-humidity HCHO vapor gas. Driven by 370 mL/min N 2 as the carrier gas, HCHO(g) was transferred to the condensing device for removing water vapour. At the same time, other gases entered into the fixed bed reactor together after being combined in multiple ways. What’s more, 0.3g sample was loaded into a quartz tube (inner diameter 10mm, length 1200mm) in a temperature-programmed tube furnace in each experiment. In each experiment, HCHO was beforehand introduced for 40 min to stabilize its concentration, then gradually increased the temperature from room temperature to 400 °C. The total flow rate of the simulated flue gas was constant at 500 mL/min, which was approximately equal to the gas hourly space velocity (GHSV) of 64000 h -1 . In addition, a PGM7340 analyzer (RAE, USA) and a PGA-650 analyzer (Phymetrix, USA) were applied to separately gauge the HCHO and CO 2 concentrations at the inlet and outlet of the reactor. Concurrently, in order to dispel the interference factors of the instrument and the pipeline, relevant blank experiments were put into effect. The abatement efficiency of HCHO was labeled as R HCHO , and its mineralization rate was signed as S cd . Meanwhile, the inlet and outlet HCHO concentrations were tabbed as [HCHO] in and [HCHO] out , respectively. The outlet CO 2 concentration in blank test was labeled as [CO 2 ] out1 , simultaneously, [CO 2 ] out2 represented the outlet CO 2 concentration (ppm) in the formal tests. R HCHO and S cd were respectively defined as the following formulas: [Fig.1] For the sake of reducing the error and guaranteeing the accuracy of the experimental results, R HCHO and S cd had taken the average value of three parallel tests, and their relative errors were controlled within 5%. 3. Results and discussion 3.1. Characterization of samples 3.1.1. BET analysis The textural and structural properties of primaeval and facilitated samples were given in Table 1. Notably, primaeval WSAC owned the largest BET surface area (729.667m 2 /g) and the largest total pore volume (0.376cm 3 /g). Nevertheless, both the BET specific surface areas and total pore volumes of facilitated WSAC samples gradually declined with the enhancement loading value of bimetallic oxides. Likewise, the micopore surface areas behaved the same descending order except for 18%Cr 0.5 Ce 0.5 /WAC. That appearance could be explained by the fact that loading metal oxides inevitably led to the blockage of partial carrier pores, and the undesirable metal oxides aggregations became more serious with the excessive loading of metal oxides 40 . The above-mentioned results were in perfect accordance with XRD and SEM analyses. Interestingly, the BET specific surface areas and pore characteristic parameters of 18%Cr 0.5 Ce 0.5 /WSAC seemed neutralized by 18%Cr 0.5 Ce 0.5 /WAC and 18%Cr 0.5 Ce 0.5 /SAC. In addition to the BET specific surface area, the amount and ratio of micro/meso/macropores were also crucial for mass transfer routes and available adsorption/catalytic sites, which exhibited significant effect on its performance 19,41 . With regard to the section of 3.2.2, it was reasonable to speculate that the hierarchical porous structure of 18%Cr 0.5 Ce 0.5 /WSAC might embody appropriate ratio of micro/meso/macropores and benefit the mass transfer and diffusion of reactants and products, which was responsible for the highest catalytic activities of HCHO elimination. Moreover, the N 2 adsorption/desorption isotherms and corresponding pore size distribution curves of as-prepared samples were depicted in Fig.2a and Fig.2b, respectively. All samples shared the typical IV isotherms with H3 hysteresis loops, which was the inherent characteristic of slit-like mesopores 42 . It was readily acknowledged that slit-like porous structure was propitious to the expeditious mass transfer of reactants and intermediates, which could exert promotional effect on catalytic reactions 43 . Howbeit, it was worth mentioning that the BET surface areas and pore properties of as-prepared samples were not in line with their catalytic performances, indicating that the BET surface areas and pore properties were not the decisive element for HCHO abatement in this work. [Table.1] [Fig.2] 3.1.2. SEM and EDX analysis The SEM images of primaeval WSAC and facilitated WSACs were demonstrated in Fig.3. The shady zones corresponded to carbon enriched areas, whereas light zones manifested the presence of CrO x -CeO x . The primitive surface characteristics of primaeval WSAC were markedly changed after loading metal oxides, which mainly scattered on the surface of facilitated WSACs 43 . It was clearly observed that a little agglomerates located in 6%Cr 0.5 Ce 0.5 /WSAC. However, superfluous shady areas meant that the surfaces of 6%Cr 0.5 Ce 0.5 /WSAC were not fully utilized. Generally speaking, better catalytic activity was archly depended upon more dispersed active metal oxides 44 . With regard to 12%Cr 0.5 Ce 0.5 /WSAC, more metal oxides appeared on available areas and more agglomerates were detected. It was noted that most surface areas of 18%Cr 0.5 Ce 0.5 /WSAC were highly covered by CrO x -CeO x , and only accredited agglomerates were observed, whereas substantial agglomerates existed in 24%Cr 0.5 Ce 0.5 /WSAC. Thus, overfull metal oxides inevitably contributed to more serious agglomerates that might hide the pores and catalytic active sites, which was unfavourable for HCHO abatement and the economy, which was in good agreement with BET results 45-47 . Furthermore, the sketchy elemental ratio of Cr and Ce of 18%Cr 0.5 Ce 0.5 /WSAC was gauged by EDX, where the detection point was marked as “spectrum” in Fig.3d. As illustrated in Fig.3f, the Cr/Ce atomic ratio was 2.01, which was approximately equal to double the Cr/Ce atomic ratio on 18%Cr 0.5 Ce 0.5 /WSAC. The observation hinted that CeO x acquired a better dispersion than that of CrO x . [Fig.3] 3.1.3. H 2 -TPR analysis The redox capacities of primaeval WSAC and facilitated WSACs were evaluated by H 2 -TPR and interrelated results were unfolded in Fig.4. The obvious reduction peaks centred at 421 °C and 612 °C in primaeval WSAC were respectively attributed to the deoxidization of surface adsorbed oxygen and gasification of WSAC matrix 19 , which were also detected in other facilitated samples. For 18%Cr/WSAC, two additional peaks observed at 300 °C and 510 °C could be referred to the consecutive reduction of Cr 6+ to Cr 3+ and the reduction of either surface/sub-surface oxygen in small Cr 2 O 3 particles 35,48 . With regard to 18%Ce/WSAC, new reduction peaks emerged at 330 °C and 580 °C, the former was attributed to the surface oxygen revivification of CeO 2 , while the latter was ascribed to the bulk oxygen depletion in structure of CeO 2 49,50 . Obviously, compared with primaeval WSAC, the reduction peaks in facilitated WSACs shifted towards lower temperature with the introduction of either CrO x or CeO x , manifesting that the presence of SMSI (Strong-Metal-Support-Interaction) between active ingredients and WSAC support 51 . In terms of 18%Cr 0.5 Ce 0.5 /WSAC, two peaks appeared at 260 °C and 345 °C were put down to the reduction of Cr 6+52 . Compared with monometallic catalysts, it was clearly seen that the reduction peaks of 18%Cr 0.5 Ce 0.5 /WSAC shifted to lower temperatures, attesting it generated better redox ability than that of 18%Cr/WSAC and 18%Ce/WSAC 44 . Such observations could be correlated with the synergistic effects between CrO x and CeO x , in which the couples of Cr 6+ /Cr 3+ and Ce 4+ /Ce 3+ facilitated each other to reduce the energy required for the electronic transfer or the generation of more surface oxygen vacancies, thus notably boosting oxygen mobility reinforcement or reactants activation 53 . On the other aspect, the hierarchical porous structure of the carrier was more conducive to the dispersion of active components 40 . Therefore, we presumed that 18%Cr 0.5 Ce 0.5 /WSAC could offer desirable catalytic performance in virtue of the synergistic effect between CrO x and CeO x and the high dispersion of active metal oxides stemmed from hierarchical pores carrier. [Fig.4] 3.1.4. XRD analysis The XRD pictorial of primaeval WSAC and facilitated WSACs were portrayed in Fig.5. It could be seen that seven peaks at 2θ = 21.96°, 26.60°, 31.48°, 33.94°, 38.76°, 44.58° and 48.84° were detected at primaeval WSAC, wherein the peaks at 2θ = 26.60° and 44.58° were in response to carbon matrix (JCPDS no. 25-0284) 21,27 , while extra peaks at 21.96°, 31.48°, 33.94°, 38.76° and 48.84° were in line with SiO 2 16,44,51 . Interestingly, they both attenuated with doping CrO x or CeO 2 , inferring that the SMSI might exist between metal oxides and WSAC 19 , as demonstrated in H 2 -TPR, SEM and XPS analyses. As regards 18%Ce/WSAC, the intrinsic peaks at 2θ = 29.46°, 34.23° and 48.65° represented the existence of CeO 2 54,55 . Additionally, with regard to 18%Cr/WSAC, the inherent peaks at 2θ = 24.63°, 33.65°, 36.27° and 65.21° were associated with the presence of Cr 2 O 3 (JCPDS No. 82-1484) 38,56,57 . Nevertheless, no signature diffraction peaks ascribed to Cr and Ce species were discovered in XCr 0.5 Ce 0.5 /WSACs compared with 18%Ce/WSAC and 18%Cr/WSAC, revealing that the interaction between Cr and Ce was propitious to generating smaller amorphous surface species 58 , which might promote surface oxygen vacancies and be the presumable justification of accelerating catalytic activity and SO 2 resistance. [Fig.5] 3.1.5. XPS analysis XPS was conducted to explore the chemical valence and composition of the elements on the surface of primaeval WSAC, fresh and used facilitated WSAC samples. The XPS spectra of O 1s, C 1s, Ce 3d and Cr 2p were demonstrated in Fig.6. As for primaeval WSAC, the three obvious sub-peaks with binding energy at 525.60-530.21 eV, 530.41-531.75 eV, 532.03-535.58 eV were observed in these specimens (Fig.6a), which could be attributable to lattice oxygen (O α ), chemically adsorbed oxygen, oxygen vacancies or hydroxyl groups (O β ), and adsorbed water species (O γ ), respectively 59 . According to reports, surface adsorbed oxygen (O β ) was more mobile than that of lattice oxygen (O α ) 60 . Meanwhile, according to the Marsvan-Krevelen mechanism, O β occupied an extremely significant position in the catalytic oxidation of VOCs, and it could complement O α through a suite of migrations and conversions 61 . Apparently, O α was visible on facilitated WSAC samples compared with primaeval WSAC, demonstrating that the introduction of metal oxides contributed to the formation of O α 19 . As an oxygen storage reservoir, O α and the oxygen-containing functional groups of the carrier could replenish O β , thereby enhancing the activity of surface oxygen 51 . Furthermore, the O β content of 18%Cr 0.5 Ce 0.5 /WSAC was significantly higher than that of 18%Cr/WSAC and 18%Ce/WSAC, revealing that more surface adsorbed oxygen engendered as a result of the synergistic effect between CrO x and CeO x . What’s more, the ratios of O α , O β , and O γ in used 18%Cr 0.5 Ce 0.5 /WSAC were different from fresh 18%Cr 0.5 Ce 0.5 /WSAC. The proportion of O β declined from 73.9% to 59.2%, while O γ and O α received an ascension, which exposed that O β participated in the reactions and was consumed in the processes. Therefore, we speculated that abundant O β on the surface of 18%Cr 0.5 Ce 0.5 /WSAC might contribute to the well-pleasing catalytic activity for HCHO abatement. [Fig.6] The XPS spectra of C 1s were displayed in Fig.6b, which could be deconvoluted into five peaks. The peaks located at 282.92-284.02 eV, 284.12-285.11 eV, 285.51-287.61 eV were respectively in association with graphitic carbons (C–C/H), carbon emerging in phenolic, ether groups (C-O) and alcohol, while other peaks situated at 287.85-288.88 eV, 289.03-294.11 eV corresponded to carbonyl groups (C=O), ester groups (COOH) or carboxyl and π-π* transitions in aromatic rings (π-π) 62,63 . As shown, the sharp and huge peaks of primaeval WSAC illustrated that the hierarchical porous carrier held extremely abundant surface functional groups. Nevertheless, once bimetallic metal oxides were loaded on WSAC, most aforementioned peaks slightly shifted toward lower binding energies except for C-C/H. That observations might be explained by that the synergistic effect between Cr and Ce oxides elevated the stability of surface oxygen-containing functional groups 50 . Additionally, with the adjunction of active components, the proportion of C-O in all facilitated samples declined significantly, while the ratios of C-C/H and COOH increased. The former could come down to C-O desorption provoked by high-temperature calcination under N 2 atmosphere, and the latter was probably affiliated with the loading of nitrate precursors 64 . For both used and fresh 18%Cr 0.5 Ce 0.5 /WSAC, the overall oxygen-containing functional groups and C-O of used samples abated, which was probably owing to the oxidation of C-O by active oxygen species in the process of HCHO abatement 65 . The XPS spectra of Cr 2p (Fig.6c) were resolved into four characteristic peaks situated at 586.66-594.11 eV, 577.11-580.22 eV, 580.52-586.31 eV, and 575.32-576.21 eV, the former two peaks pertained to Cr 6+ , and the other ones could be distinguished as Cr 3+ , signifying that Cr existed mainly in two valence states in all samples 66 . Compared with 18%Cr/WSAC, the proportion of peaks that had a bearing on Cr 6+ greatly declined after adding CeO x , which was perhaps that high-valent chromium taken over electrons from low-valent cerium. Compared with 18%Cr/WSAC, the Cr 6+ percentage of 18%Cr 0.5 Ce 0.5 /WSAC increased from 20.4% to 35.8%, while the Cr 3+ ratio of 18%Cr 0.5 Ce 0.5 /WSAC decreased from 79.6% to 64.2%. It was affirmed that the coexistence of multiple oxidative states of Cr ions was beneficial to the oxidation of VOCs 67,68 . The XPS spectra of Ce 3d were deconvoluted into eight peaks (Fig.6d), therein two peaks situated at 887.11-889.25 eV and 905.62-911.11 eV corresponded to Ce 3+ species, and other peaks centered at 884.12-884.21 eV, 893.05-895.23 eV, 900-900.41 eV, 903.42-903.65 eV, 914.81-917.51 eV, and 919.94-920.05 eV were ascribed to Ce 4+ species 37,69 . Differed from fresh 18%Ce/WSAC, the relevant peak intensities of Ce 3+ of fresh 18%Cr 0.5 Ce 0.5 /WSAC attenuated while the ratio of Ce 4+ /Ce 3+ boosted. Simultaneously, the total peak signal (Ce 3+ +Ce 4+ ) of the latter significantly ascended, promulgating that a redox cycle of Cr 6+ +Ce 3+ ↔Cr 3+ +Ce 4+ between CrO x and CeO 2 emerged and the introduction of Cr accelerated the transition of Ce into high valence states 69 . The higher Ce 4+ /Ce 3+ enhanced the conversion of oxidation states between high-valent cerium and low-valent cerium, resulting in the higher oxygen release and storage capacity, which was beneficial to the catalytic of HCHO 70 . For fresh 18%Cr 0.5 Ce 0.5 /WSAC, it could be clearly surveyed that the ratio of Ce 3+ hoisted in the comparison of used 18%Cr 0.5 Ce 0.5 /WSAC, interpreting a portion of Ce 4+ was consumed in the reactions. According to literature reports, high-valent Ce ions tended to be deactivated by preferentially reacting with SO 2 71 , however, Ce 4+ still maintained a high proportion (58.5%) in used samples, which was presumably the result of that Cr reduced the adsorption energy of SO 2 on the most stable adsorption site of CeO 2 , thereby inhibiting the sulfation of Ce 4+ and elevating SO 2 resistance 38 . Therefore, affluent high-valent Ce and Cr on 18%Cr 0.5 Ce 0.5 /WSAC advanced the efficient abatement of HCHO and boosted its excellent SO 2 resistance. 3.1.6. TG-DTG analysis To further characterize the type and content of sulfate compounds formed on used samples, the TG-DTG curves of fresh 18%Ce/WSAC, fresh 18%Cr 0.5 Ce 0.5 /WSAC, used 18%Ce/WSAC, and used 18%Cr 0.5 Ce 0.5 /WSAC were revealed. In Fig.7, all aforementioned samples presented obvious weight loss below 200 °C, which might be owing to the evaporation of adsorbed water on the surfaces 72 . For used 18%Ce/WSAC (Fig.7b), the mass wastage was classified into three stages. The first step (30~200 °C) was related to the water desorption. What's more, the second step about the weight loss within 200~500 °C could become down to the decomposition of precursors, cellulose, or lignin 73 . The third step in the high-temperature region above 450 °C could be attributed to the disintegration of Ce(SO 4 ) 2 into CeO 2 and SO 2 37 . Moreover, the mass wastage of used 18%Cr 0.5 Ce 0.5 /WSAC could been divided into four stages. The first step (50~210 °C) was ascribed to the water evaporation. Similarly, the second step (210~510 °C) was also resolved into the factorization of precursors, cellulose, or lignin 73 . The third step (510~700 °C) and the fourth step (700~1000 °C) situated in the high-temperature extent primarily pertained to the disintegration of Cr 2 (SO 2 ) 3 and Ce(SO 2 ) 2 , respectively 37,66 . Simultaneously, compared with used 18%Ce/WSAC, the lesser loss was disclosed in used 18%Cr 0.5 Ce 0.5 /WSAC, indicating that the doping of Cr enlarged thermal stability of the sample to a certain extent. In addition, the mass-loss rate of used 18%Cr 0.5 Ce 0.5 /WSAC was significantly lower than that of used 18%Ce/WSAC, which exposed that the synergistic effect between CrO x and CeO 2 reduced the engendering and coverage of surface sulfates, accordingly significantly increasing the SO 2 tolerance of such catalyst 37 . Combined with above analyses, we have plenitudinous reasons to believe that 18%Cr 0.5 Ce 0.5 /WSAC has excellent SO 2 resistance. [Fig.7] 3.2. The performance of samples 3.2.1. Effect of molar ratio of Cr/Ce It was generally appreciated that the quantity and distribution of surface adsorbed oxygen, active site and surface area of bimetallic catalysts were in close correlation with the bimetallic molar ratio 66 . Hence, the influence of the molar ratio of Cr/Ce of 18%Cr y Ce 1-y /WSACs on R HCHO was explored and the test datum were presented in Fig.8. Similarly, all 18%Cr y Ce 1-y /WSACs had broadly analogous performance trends, in which R HCHO first enhanced significantly with increasing reaction temperature and whereafter R HCHO expressed a slightly decreasing trend once the reaction temperature continuously augmented to a certain extent. The former might be because elevating the reaction temperature could furnish more kinetic energy, which was conducive to the adsorption and oxidation of HCHO 54 . At the same time, there could be a couple of reasons for the decline of R HCHO at high temperatures. High temperature inhibited the adsorption of HCHO, especially physical adsorption, which was one interpretation for the high-temperature decline of R HCHO 22,74 . The other reason might be put down to that the structure of WSAC was destructed on account of that the carbon matrix could be catalyzed into CO 2 and H 2 O by active metal oxides under high temperature 19 . On balance, 18%Cr 0.5 Ce 0.5 /WSACs behaved the best performance across the entire reaction temperature range. The superior appearance might be related to the excellent physicochemical properties caused by the synergistic action of suitable Cr and Ce oxides, forming rich active sites and large HCHO adsorption and oxidation interfaces, thereby boosting the abatement performance of HCHO 37,57 . Certainly, moderate CeO x could inhibit the agglomeration of CrO x , avoiding the loss of some accessible active sites 38 . Eventually, the optimal Cr/Ce ratio of 1:1 was used in subsequent studies. [Fig.8] 3.2.2. Effect of carrier material The carriers made from various materials typically expressed unique surface oxygen functional groups and pore structure, which affected the abatement performance of the samples by impacting the dispersion of active metal oxides and the mass transfer and timely diffusion of reactants 75 . Therefore, the possible effects of various carriers from different raw materials on HCHO abatement were disclosed in Fig.9. Obviously, 18%Cr 0.5 Ce 0.5 /WSAC behaved middle R HCHO between 18%Cr 0.5 Ce 0.5 /SAC and 18%Cr 0.5 Ce 0.5 /WAC at 80~160 °C, and then presented best R HCHO with further ascending reaction temperature, which was complied with the results of in situ DRIFTS that initially adsorption dominated for HCHO abatement at low temperature and it would be gradually superseded by catalytic oxidation at high temperature 19 . In addition, excellent HCHO catalytic oxidation performance of 18%Cr 0.5 Ce 0.5 /WSAC at 160~400 °C might be responsible by that WSAC carrier obtained more befitting proportion of micropores, mesopores and macropores, and such hierarchical porous structure immensely facilitated the mass transfer and diffusion of reactants and offspring molecules 51 . Furthermore, all the samples unveiled a debasing R HCHO trend after 280 °C, and 18%Cr 0.5 Ce 0.5 /WSAC descended lower than that of 18%Cr 0.5 Ce 0.5 /WAC and 18%Cr 0.5 Ce 0.5 /SAC. The appearance could be illustrated by that the active centres and pore structures of samples were ruined by high temperature 19 , and 18%Cr 0.5 Ce 0.5 /WSAC evinced superior thermal stability. Combined with BET analyses, the physicochemical properties of 18%Cr 0.5 Ce 0.5 /WSAC seemed to be a fantastic neutralization of 18%Cr 0.5 Ce 0.5 /WAC and 18%Cr 0.5 Ce 0.5 /SAC. Compared with them, although 18%Cr 0.5 Ce 0.5 /WSAC possessed no optimal BET surface areas and pore properties, its hierarchical porous structure could facilitate mass transfer and the diffusion of gaseous reactants and products, thus enhancing HCHO adsorption and oxidation. Besides, the suitable hierarchical porous structures of 18%Cr 0.5 Ce 0.5 /WSAC might be also partly beneficial for its preeminent thermal stability under high temperature conditions. [Fig.9] 3.2.3. Effect of active ingredients The dispersion, crystallinity, aggregation and redox property of active metal oxides were critical factors to resolve catalytic activity of samples, which were usually affected by the content and composition of active ingredients 15 . As signified in Fig.10, R HCHO of Cr or Ce solely facilitated samples evinced an apparent ascent over against with that of primaeval WSAC, implying the introduction of active ingredients vigorously boosted HCHO abatement. Especially, R HCHO of facilitated samples shown a conspicuous enlargement trend with the growth of loading value of CrCe oxides and reaction temperature, and soon afterwards exhibited a descending appearance with further raising reaction temperature. Fortunately, 18%Cr 0.5 Ce 0.5 /WSAC unfolded the uppermost catalytic activity of 99.2% at 280 °C, which was possibly connected to the good dispersion of metal oxides and more oxygen vacancies, which were confirmed by SEM results. Integrated with XPS analysis, the exceptional reducibility of 18%Cr 0.5 Ce 0.5 /WSAC could heighten the activity and mobility of lattice oxygen, ultimately accelerating HCHO oxidation 59 . In addition, Fig.10b certificated that 18%Cr 0.5 Ce 0.5 /WSAC exhibited better R HCHO than that of 18%Cr/WSAC and 18%Ce/WSAC. The phenomenon could be inferred as the synergistic effect between CrO x and CeO x ,which improved their dispersion, enhanced the amount of oxygen vacancies and perfected active oxygen mobility, thereby boosting the reducibility of Cr and Ce co-facilitated sample 44 . [Fig.10] 3.2.4. Effect of O 2 As one of pivotal gas components in industrial flue gas, O 2 occupied a momentous position in HCHO oxidation 59 . As literature reported, minuscule oxygen content easily debased the catalytic oxidation activity of catalysts 19 . However, as seen in Fig.11, 18%Cr 0.5 Ce 0.5 /WSAC still preserved a high activity (R HCHO =86.1%) without oxygen (SFG-6%O 2 ), which could be rooted in the residual lattice oxygen (O α ) and surface active oxygen (O β ) could timely participate in the HCHO oxidation reactions, and this was in well accordance with XPS analysis. Compared with SFG-6%O 2 , the substantially ascending R HCHO (97.2%) under SFG condition stated clearly that O 2 had the positive effect on R HCHO , whichwasattributed to that the pull-in of gas-phase oxygen supplemented consumed lattice oxygen and surface adsorbed oxygen 19 . With the further enlargement of O 2 (SFG+6%O 2 ), only a slight exaltation of R HCHO was observed (R HCHO =99.9%), implying that the O 2 content in the actual flue gas was sufficient to satisfy HCHO oxidation. [Fig.11] 3.2.5. Effect of SO 2 As one of significant interfering gas components in industrial flue gas, SO 2 inevitably affected the R HCHO of the samples 69 . In Fig.12 (SO 2 ), a slight decrease was detected for the HCHO abatement performance of 18%Cr 0.5 Ce 0.5 /WSAC when 300 ppm SO 2 was added into the SFG, while more and more obvious decline could be observed with increasing SO 2 concentration. The above phenomenon could be attributed to two possible causes: on the one hand, a certain degree of competitive adsorption existed between SO 2 and HCHO due to various polarity 51 . On the other hand, the active phase was poisoned and inactivated by SO 2 reacting with metal oxides, and such generating metal sulfides might block some pores and overlay partial active sites, thus interrupting the redox cycling of HCHO oxidation 76 . In addition, the satisfactory catalytic activity of 18%Cr 0.5 Ce 0.5 /WSAC at high SO 2 concentration indicated that 18%Cr 0.5 Ce 0.5 /WSAC possessed fine SO 2 resistance, which might be interpreted by that appropriate amount doping of CrO x effectively defended the active center of Ce species. Simultaneously, integrated with aforementioned characterization analyses, the hierarchical porous structure of 18%Cr 0.5 Ce 0.5 /WSAC further elevated SO 2 tolerance 77,78 . [Fig.12] 3.2.6. Effect of H 2 O and SO 2 The presence of water vapor in industrial flue gas frequently interfered the catalytic performance of catalysts. In general, the R HCHO of the samples would drop for the competitive adsorption of H 2 O molecules with HCHO molecules 51 . Unexpectedly, as shown in Fig.12 (H 2 O), the introduction of 3% H 2 O not only presented no negative influence on R HCHO , on the contrary, the R HCHO of aforementioned samples displayed a tiny rise with the increase of H 2 O influx (8%H 2 O). Combined with XPS analysis, the abnormality might be connected to the reaction of adsorbed water with surface active oxygen to generate active hydroxyl groups, thereby supplementing the consumed O β 59 . Moreover, H 2 O presented the gainful role in promoting the conversion of formic acid intermediates, so it then accelerated the elimination of HCHO 79 . Interestingly, the adsorption of water vapor did tend to encumber pores and active centers 79 . Synthesizing the above feasible mechanisms, we inferred that the promotional effect of H 2 O molecule on the catalytic activity was slightly higher than its inhibitory effect, and the carrier’ hierarchical porous structure might greatly enhance the hydrophobicity, which further avoided the disadvantage of water clogging and enhanced its H 2 O tolerance. In addition, the inhibitory effect of SO 2 was alleviated by means of the promoting function of water vapor to some extent. As shown in Fig.12 (SO 2 +H 2 O), compared with SFG+300ppm SO 2 , a small rise of R HCHO of the sample was caught after sequentially adding 3% H 2 O, which was in line with the above promoting effect of water vapor. Curiously, 18%Cr 0.5 Ce 0.5 /WSAC revealed a higher R HCHO after injecting higher concentration water vapor (8%H 2 O) into SFG+800ppmSO 2 , even exceeding that under SFG+300ppmSO 2 +3%H 2 O, revealing that the SO 2 toxicity of the sample was mitigated under higher humidity, which might be owing to the fact that higher concentration of H 2 O sped up the routing of converting adsorbed SO 2 into sulfuric acid, and the mighty internal transport capacity of the hierarchical porous structure further scissored the retention of sulfuric acid in the pores 79,80 . Therefore, 18%Cr 0.5 Ce 0.5 /WSAC might exhibit excellent resistance to SO 2 and H 2 O under general industrial flue gas conditions. 3.3. Stability and selectivity test The stability and selectivity test results of 18%Cr 0.5 Ce 0.5 /WSAC catalyst for HCHO abatement were assembled in Fig.13. Under SFG conditions, the stability test of 18%Cr 0.5 Ce 0.5 /WSAC sustained for 30 hours. In the first 6 hours, R HCHO decreased from 99.2% to 96.8%, and then remained at around 93.7%. The R HCHO declined after the accession of 300 ppm SO 2 to SFG, but the addition of 8%H 2 O slashed this negative trend and even exhibited higher R HCHO than that under SFG, which was consonant with the aforesaid performance test analyses. S cd also exhibited an identical trend, albeit slightly stronger than R HCHO , and it suffered from the compositive impact of 8%H 2 O and 300 ppm SO 2 ,which affected R HCHO . Some intermediates such as DOM and formate were produced during the abatement of HCHO, which were in line with the subsequent results of in situ DRIFTS. Eventually, R HCHO and S cd of 18%Cr 0.5 Ce 0.5 /WSAC remained at about 93.5% and 93.7% under 300 ppm SO 2 , demonstrating that it behaved distinguished stability and selectivity. [Fig.13] 4. Intermediates and mechanism The in situ DRIFTS tests were conducted to illustrate the reaction pathways and intermediates of HCHO abatement on 18%Cr 0.5 Ce 0.5 /WSAC. As displayed in Fig.14, after feeding 200 ppm HCHO+6%O 2 /N 2 for only 10 minutes, a peak pertained to the adsorption of HCHO molecules was disclosed at 1135 cm -1 , which manifested that HCHO was firstly adsorbed on the sample surface 81 . Its intensity progressively attenuated after 10 minutes, illustrating that the hierarchical porous structure of 18%Cr 0.5 Ce 0.5 /WSAC possibly accelerated the adsorption and subsequent oxidation of HCHO 19 . The bands situated in 2943, 1061, and 809 cm -1 respectively belonged to v s (CH 2 ), ω(CH 2 ), and v(C-O) of dioxymethylene (DOM) 59 , implying that the adsorbed HCHO was oxidized into DOM in virtue of its carbonyl electrophilic carbon being attacked by surface nucleophilic surface oxygen [80]. The formation and consumption of DOM attained a dynamic equilibrium after 40 min. Meanwhile, several bands occurred in 1463 and 1387 cm -1 were associated with ν as (COO) and ν s (COO) modes of formate species, respectively 53,55 . Moreover, the formate species were generally adsorbed on the catalyst surface in three configurations: bridging, monodentate and bidentate (chelated) frameworks, which could be discriminated via the frequency interval between ν as (COO) and ν s (COO) 44 . Nevertheless, the intensity of the spectral stretching vibration connected to formate species sustained stable between 10 and 40 min, reflecting that the emergence and consumption of formate species demonstrated a balance, and its diminished intensity after 40 min revealed that the emergence of DOM was constrained, which might correspond to SO 2 poisoning of active metals 37,66 . Furthermore, the characteristic peaks of adsorbed CO 2 and H 2 O (bands at 3484 and 2334 cm -1 ) might generate during the oxidation processes of formate species 70 . The uplifted intensities of corresponding CO 2 peak were clearly observed after being exposed to 200 ppm HCHO + 6% O 2 /N 2 for only 10minutes, which was possibly owing to the quick oxidation of HCHO at the reaction begins. The surface hydroxyl groups (-OH) that consumed in the oxidation reactions corresponding to the negative bands located at 3690 cm -1 , which would be steadily restocked owing to active oxygen activating adsorbed H 2 O molecules 6 . Furthermore, all of the above-mentioned peak intensities reduced marginally between 40 and 50 minutes, while then recovered slightly after 50 minutes. This appearance might be in virtue of the production of metal sulfates mulching the active sites and partial apertures, causing the diminished adsorption and catalytic oxidation of HCHO, and the addition of H 2 O could relieve SO 2 poisoning. [Fig.14] In the light of above-mentioned analyses, both adsorption and catalytic oxidation worked together for HCHO decontamination over 18%Cr 0.5 Ce 0.5 /WSAC, and the hierarchical porous structure of the carrier accelerated the process. With the comprehension of in-situ DRIFTS, it is proposed that HCHO oxidation obeyed Mars-van-Krevelen mechanism 54,70 . The detailed reaction procedures were presented in Fig.15. Firstly, HCHO was captured by superficial hydroxyl groups and other active sites on the surface of 18%Cr 0.5 Ce 0.5 /WSAC. Then, adsorbed HCHO would react with surface active oxygen comprising chemisorbed oxygen and lattice oxygen (marked as O s ), in which the nucleophilic O s crashed C-H of adsorbed HCHO reforming carbonyl groups into DOM, and DOM was rapidly oxidized into formate species. Meanwhile, formate intermediates after the loss of a hydrogen bond were further oxidized by active hydroxyl groups into unstable H 2 CO 3 and whereafter it decomposed into CO 2 and H 2 O (Eqs. (3)-(11)). Furthermore, the lost hydrogen bond would integrate with the unbonded -OH adsorbed on the catalyst surface, composing H 2 O (Eqs. (12)) 19,51 . On the whole, the specific reaction pathways were speculated as follows: HCHO (g) +WSAC (surface) →HCHO (ad) (3) O 2(g) +WSAC (surface) →O 2(ad) (4) 2CrO 3 →Cr 2 O 3 +3O s (5) 6CeO 2 +Cr 2 O 3 →3Ce 2 O 3 +2CrO 3 (6) 2CeO 2 →Ce 2 O 3 +O s (7) Ce 2 O 3 +O (ad) →2CeO 2 (8) HCHO (ad) +2CrO 3 →CHO+Cr 2 O 3 +H + +3O s - (9) O s - +CHO→HCOO - (10) HCOO - +OH→CO 2 +H 2 O (11) H + +OH→H 2 O (12) [Fig.15] 5. Conclusions A series of CrO x -CeO x facilitated hierarchical porous biochars derived from walnut husks and rice straws were readily synthesized to investigate for HCHO abatement. The physicochemical properties and abatement mechanism of above-mentioned samples were evaluated by means of BET, XRD, SEM, EDX, H 2 -TPR, XPS, TG-DTG and in situ DRIFTS. The textural parameters including BET surface area, micropore surface area and micropore volume of 18%Cr 0.5 Ce 0.5 /WSAC seemed neutralized by 18%Cr 0.5 Ce 0.5 /WAC and 18%Cr 0.5 Ce 0.5 /SAC. 18%Cr 0.5 Ce 0.5 /WSAC exhibited superior R HCHO , favorable thermal stability and excellent resistance to SO 2 and H 2 O in a wide temperature window from 160 to 400℃ partly due to hierarchical porous structure with appropriate ratio of micro-meso-macropores. The boosting effect of H 2 O could alleviate the inhibitory effect of SO 2 . Cr and Ce co-modified WSAC exhibited better performance than that of Cr or Ce individually modified WSAC, which was attributed to the redox cycle of Cr 6+ +Ce 3+ ↔Cr 3+ +Ce 4+ and the synergistic effect between CrO x and CeO x , resulting in more active oxygen mobility, higher redox ability and better dispersion of metal oxides. Besides, the hierarchical porous structure of support not only furnished abundant surface functional groups, but also facilitated the accessibility of adsorption/catalytic active sites and boosted the convenient mass transfer of reactants and products. Therefore, these superior properties contributed to boosting the catalytic performance, enhancing the thermal stability and perfecting the resistance to SO 2 and H 2 O. Moreover, both adsorption and catalytic oxidation worked together for HCHO elimination over 18%Cr 0.5 Ce 0.5 /WSAC. Meanwhile, catalytic oxidation predominated gently with the augmentation of reaction time. Declarations Acknowledgements This study was financially supported by the Natural Science Foundation of Hunan Province (2024JJ5335), the Scientific Research Project of Hunan Provincial Department of Education (22B0458), the National Natural Science Foundation of China (52270102). Data availability All data generated or analysed during the current study are provided in the manuscript. References Kim, W.-K., Vikrant, K., Younis, S.A., Kim, K.-H., Heynderickx, P.M. Metal oxide/activated carbon composites for the reactive adsorption and catalytic oxidation of formaldehyde and toluene in air. J. Cleaner. Prod. 387, 135925 (2023). https://doi.org/10.1016/j.jclepro.2023.135925. Chen, S. et al. Unravelling the critical role of silanol in Pt/SiO 2 for room temperature HCHO oxidation: an experimental and DFT study. Appl. Catal. B. 331, 122672 (2023). https://doi.org/10.1016/j.apcatb.2023.122672. Cruz, M.D., Svenningsen, N.B., Nybroe, O., Müller, R., Christensen, J.H. Removal of a complex VOC mixture by potted plants-effects on soil microorganisms. Environ. Sci. Pollut. Res. 30, 55372-55381 (2023). https://10.1007/s11356-023-26137-8. Diao, W., Xu, J., Rao, X., Zhang, Y. Facile Synthesis of Fluorine Doped Rutile TiO 2 Nanorod Arrays for Photocatalytic Removal of Formaldehyde. Catal. Lett. 152, 1029-1039 (2022). https://10.1007/s10562-021-03700-x. González-Martín, J., Cantera, S., Lebrero, R., Muñoz, R. Biofiltration based on bioactive coatings for the abatement of indoor air VOCs. Sustainable Chem. Pharm. 31, 100960 (2023). https://10.1016/j.scp.2022.100960. Li, J. et al. Construction of Pt-MnO 2 interface with strong electron coupling effect for plasma catalytic oxidation of aromatic VOCs. Colloids. Surf. A. 665, 131248 (2023). https://10.1016/j.colsurfa.2023.131248. Wang, J., Shi, Y., Kong, F., Zhou, R. Low-temperature VOCs oxidation performance of Pt/zeolites catalysts with hierarchical pore structure. J. Environ. Sci. 124, 505-512 (2023). https://10.1016/j.jes.2021.11.016. Zheng, Y. et al. Revealing Opposite Behaviors of Catalyst for VOCs Oxidation: Modulating Electronic Structure of Pt Nanoparticles by Mn Doping. Chem. Eng. J. 465, 142807 (2023). https://doi.org/10.1016/j.cej.2023.142807. Yu, Q. et al. Layered double hydroxides-based materials as novel catalysts for gaseous VOCs abatement: Recent advances and mechanisms. Coord. Chem. Rev. 471, 214738 (2022). https://10.1016/j.ccr.2022.214738. Xia, T. et al. Nano-Au supported on CeO 2 for plasma catalytic degradation of n-undecane: Enhancement of activity and stability. Sep. Purif. Technol. 314, 123497 (2023). https://doi.org/10.1016/j.seppur.2023.123497. Seo, B. et al. Computational screening-based development in VOC removal catalyst: Methyl ethyl ketone oxidation over Pt/TiO 2 . Chem. Eng. J. 452 (4) , 139466 (2023). https://10.1016/j.cej.2022.139466. Li, J. et al. Boosting the plasma catalytic performance of CeO 2 /γ-Al 2 O 3 in long-chain alkane VOCs via tuning the crystallite size. Appl. Surf. Sci. 611, 155742 (2023). https://10.1016/j.apsusc.2022.155742. Chen, Y. et al. CoO x supported on rice-husk derived SiO 2 for styrene combustion: The balance of low temperature activity and thermal stability. Appl. Surf. Sci. 606, 154851 (2022). https://10.1016/j.apsusc.2022.154851. Shi, Y., Wan, J., Kong, F., Wang, Y., Zhou, R. Influence of Pt dispersibility and chemical states on catalytic performance of Pt/CeO 2 -TiO 2 catalysts for VOCs low-temperature removal. Colloids Surf., A. 652, 129932 (2022). https://10.1016/j.colsurfa.2022.129932. Lu, S., Li, K., Huang, F., Chen, C., Sun, B. Efficient MnO x -Co 3 O 4 -CeO 2 catalysts for formaldehyde elimination. Appl. Surf. Sci. 400, 277-282 (2017). https://10.1016/j.apsusc.2016.12.207. Wang, Y., Wang, F., Han, F., Shi, W., Yu, H. Ultra-small CeO 2 nanoparticles supported on SiO 2 for indoor formaldehyde oxidation at low temperature. Catal. Sci. Technol. 10, 6701-6712 (2020). https://doi.org/10.1039/D0CY00988A. Cai, T. et al. Great activity enhancement of Co 3 O 4 /γ-Al 2 O 3 catalyst for propane combustion by structural modulation. Chem. Eng. J. 395, 125071 (2020). https://10.1016/j.cej.2020.125071. Shen, Y. Biomass-derived porous carbons for sorption of Volatile organic compounds (VOCs). Fuel. 336, 126801 (2023). https://10.1016/j.fuel.2022.126801. Gao, L. et al. Excellent performance and outstanding resistance to SO 2 and H 2 O for formaldehyde abatement over CoMn oxides boosted dual-precursor hierarchical porous biochars derived from liquidambar and orange peel. Fuel. 317, 123539 (2022). https://10.1016/j.fuel.2022.123539. Yang, C. et al. Abatement of various types of VOCs by adsorption/catalytic oxidation: A review. Chem. Eng. J. 370, 1128-1153 (2019). https://10.1016/j.cej.2019.03.232. Yao, F. et al. Characterization of physicochemical properties of activated carbons prepared from penicillin mycelial residues and its adsorption properties for VOCs. J. Environ. Chem. Eng. 11 (3) , 109733 (2023). https://10.1016/j.jece.2023.109733. Liu, X. et al. Carbon materials with hierarchical porosity: Effect of template removal strategy and study on their electrochemical properties. Carbon. 130, 680-691 (2018). https://doi.org/10.1016/j.carbon.2018.01.046. An, B. et al. Cooperative copper centres in a metal-organic framework for selective conversion of CO 2 to ethanol. Nat. Catal . 2, 709-717 (2019). https://doi:10.1038/s41929-019-0308-5. Qu, Z. et al. A new insight into SO 2 low-temperature catalytic oxidation in porous carbon materials: nondissociated O 2 molecule as oxidant. Catal. Sci. Technol. 9, 4327-4338 (2019). https://10.1039/C9CY00960D. Jin, X. et al. Catalytic conversion of toluene by biochar modified with KMnO 4 . Fuel. 332 (2) , 126237 (2023). https://10.1016/j.fuel.2022.126237. Cheng, S. et al. Efficient removal of heavy metals from aqueous solutions by Mg/Fe bimetallic oxide-modified biochar in monometallic and bimetallic systems: Experiments and DFT investigations. J. Cleaner. Prod. 403, 136821 (2023). https://doi.org/10.1016/j.jclepro.2023.136821. Tu, S. et al. Complete catalytic oxidation of formaldehyde at room temperature on Mn x Co 3-x O 4 catalysts derived from metal-organic frameworks. Appl. Catal. A. 611, 117975 (2021). https://10.1016/j.apcata.2020.117975. Zeng, Y. et al. CoMn 2 O 4 supported on carbon nanotubes for effective low-temperature HCHO removal. J. Alloy. Compd. 859, 157808 (2021). https://10.1016/j.jallcom.2020.157808. Zhu, Y. et al. Regulating CeO 2 morphologies on the catalytic oxidation of toluene at lower temperature: A study of the structure-activity relationship. J. Catal. 418, 151-162 (2023). https://doi.org/10.1016/j.jcat.2023.01.012. Li, Z. et al. CeO 2 from pyrolysis of MOFs for efficient catalytic combustion of VOCs. Mol. Catal. 535, 112857 (2023). https://10.1016/j.mcat.2022.112857. Li, L. et al. Effects of different methods of introducing Mo on denitration performance and anti-SO 2 poisoning performance of CeO 2 . Chin. J. Catal. 42 (9) , 1488-1499 (2021a). https://10.1016/S1872-2067(20)63778-0. Zhu, L. et al. NH 3 -SCR performance and SO 2 resistance comparison of CeO 2 based catalysts with Fe/Mo additive surface decoration. Chem. Eng. J. 428 (15) , 131372 (2022). https://10.1016/j.cej.2021.131372. Zhang, N. et al. Synchronously constructing the optimal redox-acidity of sulfate and RuO x Co-modified CeO 2 for catalytic combustion of chlorinated VOCs. Chem. Eng. J. 454, 140391 (2023). https://10.1016/j.cej.2022.140391. Xiao, M. et al. Ni-doping-induced oxygen vacancy in Pt-CeO 2 catalyst for toluene oxidation: Enhanced catalytic activity, water-resistance, and SO 2 -tolerance. Appl. Catal. B. 323, 122173 (2023). https://10.1016/j.apcatb.2022.122173. Yu, S. et al. Synthesis of CrO x /C catalysts for low temperature NH 3 -SCR with enhanced regeneration ability in the presence of SO 2 . RSC. Adv. 8 (7) , 3858-3868 (2018). https://10.1039/c7ra09680a. Jia, Y. et al. Investigation of the Effect of SO 2 and H 2 O on VPO-Cr-PEG/TiO 2 for the Low-Temperature SCR de-NO x . Front. Mater. 6, 320 (2019). https://10.3389/fmats.2019.00320. Liu, W. et al. Promotion Effect of Chromium on the Activity and SO 2 Resistance of CeO 2 -TiO 2 Catalysts for the NH 3 -SCR Reaction. Ind. Eng. Chem. Res. 60 (31) , 11676-11688 (2021). https://10.1021/acs.iecr.1c00898. Zhang, D. et al. Cr Doping MnO x Adsorbent Significantly Improving Hg 0 Removal and SO 2 Resistance from Coal-Fired Flue Gas and the Mechanism Investigation. Ind. Eng. Chem. Res. 57 (50) , 17245-17258 (2018). https://10.1021/acs.iecr.8b04857. Yang, P., Zuo, SF., Shi, Z.N., Tao, F., Zhou, R.X. Elimination of 1,2-dichloroethane over (Ce,Cr) x O 2 /MO y catalysts (M = Ti, V, Nb, Mo, W and La). Appl. Catal. 191, 53-61 (2016). https://doi.org/10.1016/j.apcatb.2016.03.017. Xia, C. et al. Recent Advances on Electrospun Nanomaterials for Zinc-Air Batteries. Small. Sci. 1, 1-16 (2021). https://10.1002/smsc.202100010. Qin, J. et al. Self-activation of potassium/iron citrate-assisted production of porous carbon/porous biochar composites from macroalgae for high-performance sorption of sulfamethoxazole. Bioresour. Technol. 369, 128361 (2023). https://10.1016/j.biortech.2022.128361. Ye, G. et al. Preparing hierarchical porous carbon with well-developed microporosity using alkali metal-catalyzed hydrothermal carbonization for VOCs adsorption. Chemosphere. 298, 134248 (2022). https://10.1016/j.chemosphere.2022.134248. Zhu, L., Shen, D., Luo, K.H. A critical review on VOCs adsorption by different porous materials: Species, mechanisms and modification methods. J. Hazard. Mater. 389, 122102 (2020). https://10.1016/j.jhazmat.2020.122102. Gao, L. et al. Superior performance and resistance to SO 2 and H 2 O over CoO x -modifed MnO x /biomass activated carbons for simultaneous Hg 0 and NO removal. Chem. Eng. J. 371, 781-795 (2019). https://10.1016/j.cej.2019.04.104. Venkataswamy, P. et al. Cr-Doped CeO 2 Nanorods for CO Oxidation: Insights into Promotional Effect of Cr on Structure and Catalytic Performance. Catal. Lett. 150, 948-962 (2020). https://10.1007/s10562-019-03014-z. Gao, E. et al. Understanding the co-effects of manganese and cobalt on the enhanced SCR performance for Mn x Co 1x Cr 2 O 4 spinel-type catalysts. Catal. Sci. Technol. 10, 4752-4765 (2020). https://10.1039/D0CY00872A. Tachibana, N., Yukawa, Y., Morikawa, K., Kawaguchi, M., Shimanoe, K. Pt nanoparticles supported on nitrogen‑doped porous carbon as efficient oxygen reduction catalysts synthesized via a simple alcohol reduction method. SN. Appl. Sci. 3, 338 (2021). https://10.1007/s42452-021-04343-8. Wang, J., Yang, P., Guo, X., Zhou, R. Investigation on the structure-activity relationship of Nb 2 O 5 promoting CeO 2 -CrO x -Nb 2 O 5 catalysts for 1,2-dichloroethane elimination. Mol. Catal. 470, 75-81 (2019). https://10.1016/j.mcat.2019.03.010. Jiang, G. et al. Insight into the Ag-CeO 2 interface and mechanism of catalytic oxidation of formaldehyde. Appl. Surf. Sci. 549, 149277 (2021). https://10.1016/j.apsusc.2021.149277. Gao, L. et al. Simultaneous removal of NO and Hg 0 from simulated fiue gas over CoO x -CeO 2 loaded biomass activated carbon derived from maize straw at low temperatures. Chem. Eng. J. 342, 339-349 (2018). https://10.1016/j.cej.2018.02.100. Du, X. et al. Promotional removal of HCHO from simulated flue gas over Mn-Fe oxides modified activated coke. Appl. Catal. B. 232, 37-48 (2018). https://10.1016/j.apcatb.2018.03.034. Xu, C., Jin, L., Wang, X., Chen, Y., Dai, L. Honeycomb-like porous Ce-Cr oxide/N-doped carbon nanostructure: Achieving high catalytic performance for the selective oxidation of cyclohexane to KA oil. Carbon. 160, 287-297 (2020a). https://doi.org/10.1016/j.carbon.2020.01.023. Xu, J., Qu, Z., Ke, G., Wang, Y., Huang, B. Catalytic activity of gold-silver nanoalloys for HCHO oxidation: Effect of hydroxyl and particle size. Appl. Surf. Sci. 513, 145910 (2020b). https://10.1016/j.apsusc.2020.145910. Yu, C. et al. A MnO x @Eu-CeO x nanorod catalyst with multiple protective effects: Strong SO 2 -tolerance for low temperature DeNO x processes. J. Haz. Mat. 399, 123011 (2020). https://10.1016/j.jhazmat.2020.123011. Li, R. et al. Improved Oxygen Activation over a Carbon/Co 3 O 4 Nanocomposite for Efficient Catalytic Oxidation of Formaldehyde at Room Temperature. Environ. Sci. Technol. 55, 4054-4063 (2021c). https://10.1021/acs.est.1c00490. Xie, J. et al. Exploring removal of formaldehyde at room temperature over Cr- and Zn-modified Co 3 O 4 catalyst prepared by hydrothermal method. Res. Chem. Intermed. 46, 1789-1804 (2020). https://10.1007/s11164-019-04063-0. Fu, Z. et al. Promotional effect of SO 2 on Cr 2 O 3 catalysts for the marine NH 3 -SCR reaction. Chem. Eng. J. 361, 830-838 (2019). https://10.1016/j.cej.2018.12.100. Liu, Z. et al. Catalytic Oxidation of Formaldehyde over Manganese-Based Catalysts and the Influence of Synergistic Effect(Review). Prog. Chem. 31 (2-3) , 311-321 (2019). https://10.7536/PC180435. Du, X. et al. Highly efficient simultaneous removal of HCHO and elemental mercury over Mn-Co oxides promoted Zr-AC samples. J. Haz. Mat. 408, 124830 (2021). https://10.1016/j.jhazmat.2020.124830. Lin, X. et al. Evolution of oxygen vacancies in MnO x -CeO 2 mixed oxides for soot oxidation. Appl. Catal. B. 223, 91-102 (2018). https://10.1016/j.apcatb.2017.06.071. Lyu, Y. et al. Catalytic oxidation of toluene over MnO 2 catalysts with diferent Mn (II) precursors and the study of reaction pathway. Fuel. 262, 116610 (2020). https://doi.org/10.1016/j.fuel.2019.116610. Yi, L. et al. LaO x modified MnO x loaded biomass activated carbon and its enhanced performance for simultaneous abatement of NO and Hg 0 . Environ. Sci. Pollut. R. 29, 2258-2275 (2022). https://10.1007/s11356-021-15752-y. Zhang, H. et al. Structure, surface and reactivity of activated carbon: From model soot to Bio Diesel soot. Fuel. 257, 116038 (2019). https://10.1016/j.fuel.2019.116038. Zhang, D. et al. Efficient removal of formaldehyde by polyethyleneimine modified activated carbon in a fixed bed. Environ. Sci. Pollut. Res. 27 (15) , 18109-18116 (2020). https://10.1007/s11356-020-08019-5. Li, Y., Liu, Y., Yang, W., Liu, L., Pan, J. Adsorption of elemental mercury in flue gas using biomass porous carbons modified by microwave/hydrogen peroxide. Fuel. 291, 120152 (2021b). https://10.1016/j.fuel.2021.120152. Chen, G. et al. CrO x -MnO x -TiO 2 adsorbent with high resistance to SO 2 poisoning for Hg 0 removal at low temperature. J. Ind. Eng. Chem. 55, 119-127 (2017). https://10.1016/j.jiec.2017.06.035. Feng, X. et al. Yolk-shell-like mesoporous CoCrO x with superior activity and chlorine resistance in dichloromethane destruction. Appl. Catal. B. 264, 118493 (2020). https://10.1016/j.jiec.2017.06.035. Wu, J., Xia, Q., Xiao, J., Li, Z. Chromium-based metal-organic framework MIL-101 as a highly effective catalyst in plasma for toluene removal. J. Phys. D. 50, 475202 (2017). https://10.1088/1361-6463/aa90f3. Fang, X., Liu, Y., Cheng, Y., Cen, Y. Mechanism of Ce-Modified Birnessite-MnO 2 in Promoting SO 2 Poisoning Resistance for Low-Temperature NH 3 -SCR. ACS. Catal. 11, 4125-4135 (2021). https://10.1021/acscatal.0c05697. Chen, J. et al. Incorporating Mn cation as anchor to atomically disperse Pt on TiO 2 for lowtemperature removal of formaldehyde. Appl. Catal. B. 259, 118013 (2019). https://10.1016/j.apcatb.2019.118013. Li, H. et al. Enhanced activity and SO 2 resistance of Co-modified CeO 2 -TiO 2 catalyst prepared by facile co-precipitation for elemental mercury removal in flue gas. Appl. Organomet. Chem. 34 (4) , e5463 (2020). https://10.1002/aoc.5463. Zhang, Z., Yang, B., Ma, H. Aliphatic Amine Decorating Metal-Organic Framework for Durable SO 2 Capture from Flue Gas. Sep. Purif. Technol. 259, 118164 (2021). https://10.1016/j.seppur.2020.118164. Tazibet, S., Velasco, L. F., Lodewyckx, P., MHamed, D.A., Boucheffa, Y. Systematic study of the role played by ZnCl 2 during the carbonization of a chemically activated carbon by TG-MS and DSC. J. Therm. Anal. Calorim. 134 (3) , 1395-1404 (2018) . https://10.1007/s10973-018-7246-3. Rahbar-Shamskar, K., Rashidi, A., Baniyaghoob, S., Khodabakhshi, S. In-situ catalytic fast pyrolysis of reed as a sustainable method for production of porous carbon as VOCs adsorbents. J. Anal. Appl. Pyrolysis. 164, 105520 (2022). https://10.1016/j.jaap.2022.105520. Zhang, H., Tan, L., Zhang, Z., Zhang, G., Lu, J. Activated carbon and poly-o-anisidine (POA) synergistic supported Pt nanoparticles as a highly efficient catalyst for electrocatalytic oxidation of formaldehyde. Electrochim. Acta. 388, 138617 (2021). https://10.1016/j.electacta.2021.138617. Saad, M., Szymaszek, A., Biafias, A., Samojeden, B., Motak, M. SO 2 Poisoning and Recovery of Copper-Based Activated Carbon Catalysts for Selective Catalytic Reduction of NO with NH 3 at Low Temperature. Catalysts. 10 (12) , 1426 (2020). https://10.3390/catal10121426. Shao, J. et al. Enhance SO 2 adsorption performance of biochar modified by CO 2 activation and amine impregnation. Fuel. 224, 138-146 (2018). https://10.1016/j.fuel.2018.03.064. Yu, J. et al. Insight into the key factors in fast adsorption of organic pollutants by hierarchical porous biochar. J. Haz. Mat. 403, 123610 (2021). https://10.1016/j.jhazmat.2020.123610. Ma, C. et al. Effects of H 2 O on HCHO and CO oxidation at room-temperature catalyzed by MCo 2 O 4 (M=Mn, Ce and Cu) materials. Appl. Catal. B. 254, 76-85 (2019). https://10.1016/j.apcatb.2019.04.085. Li, B., Ma, C. Study on the mechanism of SO 2 removal by activated carbon. Energy Procedia. 153, 471-477 (2018). https://10.1016/j.egypro.2018.10.063. Xiang, N. et al. Promoting effect and mechanism of alkali Na on Pd/SBA-15 for room temperature formaldehyde catalytic oxidation. Chem. Cat. Chem. 11, 5098-5107 (2019). http://dx.doi.org/10.1002/cctc.201901039. Tables Table.1. The BET specific surface area and pore characteristic parameters of primaeval WSAC and modified samples. Sample BET surface area (m 2 /g) Micopore area (m 2 /g) Micopore ratio (%) Total pore volume (cm 3 /g) Micopore volume (cm 3 /g) Average pore diameter (nm) primaeval WSAC 729.667 577.145 79.1% 0.376 0.239 2.059 6%Cr 0.5 Ce 0.5 /WSAC 547.779 412.734 75.4% 0.285 0.172 2.077 12%Cr 0.5 Ce 0.5 /WSAC 426.674 319.984 75.7% 0.218 0.132 2.045 18%Cr 0.5 Ce 0.5 /WSAC 407.439 323.039 78.5% 0.211 0.133 2.068 24%Cr 0.5 Ce 0.5 /WSAC 369.662 280.231 75.8% 0.190 0.115 2.055 18%Cr 0.5 Ce 0.5 /WAC 689.071 622.516 90.3% 0.307 0.256 1.785 18%Cr 0.5 Ce 0.5 /SAC 373.594 197.819 52.9% 0.225 0.086 2.405 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5297317","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":376192651,"identity":"949b053f-aa15-43fd-b683-464995d55305","order_by":0,"name":"Yun Jiang","email":"","orcid":"","institution":"University of South China","correspondingAuthor":false,"prefix":"","firstName":"Yun","middleName":"","lastName":"Jiang","suffix":""},{"id":376192652,"identity":"599a170b-fec5-483a-9beb-4416d6bac4cc","order_by":1,"name":"Xiaoxin Feng","email":"","orcid":"","institution":"University of South 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installation.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/aac7e8b1992857bb4fd3adde.png"},{"id":69328181,"identity":"42ee0717-5151-4d62-bb5a-df330fcb35bc","added_by":"auto","created_at":"2024-11-19 08:32:04","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":3161158,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Nitrogen adsorption and desorption isotherm curves and (b) BJH pore size distribution curves for primaeval WSAC and modified WSACs, WAC and SAC.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/157e16c7e5d7f5c60c08d333.png"},{"id":69328186,"identity":"502398d1-aed7-497f-a339-b85eac7e0c47","added_by":"auto","created_at":"2024-11-19 08:32:04","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":4167576,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of (a) primaeval WSAC, (b) 6%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC, (c) 12%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC, (d) 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC, (e) 24%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/42220166ba178c5f4d431741.png"},{"id":69329057,"identity":"b4d3c097-4f5a-4682-8a06-514d2933feff","added_by":"auto","created_at":"2024-11-19 08:40:04","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1389148,"visible":true,"origin":"","legend":"\u003cp\u003eH\u003csub\u003e2\u003c/sub\u003e-TPR profiles of primaeval WSAC and modified WSACs.\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/1b4ef1e03635224e54afaf2c.png"},{"id":69328183,"identity":"d06d8068-2cca-429b-91dd-4837318ffc9c","added_by":"auto","created_at":"2024-11-19 08:32:04","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":907672,"visible":true,"origin":"","legend":"\u003cp\u003eXRD results of primaeval WSAC and modified WSACs.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/ac4473652e98fb93f5f761e0.png"},{"id":69329061,"identity":"30c7ea0e-679f-4115-a6d5-442e6df21eeb","added_by":"auto","created_at":"2024-11-19 08:40:04","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":4048752,"visible":true,"origin":"","legend":"\u003cp\u003eThe XPS analyses of O 1s (a), C 1s (b), Cr 2p (c) and Ce 3d (d) for primaeval WSAC, fresh 18%Cr/WSAC or fresh 18%Ce/WSAC, fresh and used 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC.\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/081566316a204a0da93e3e4d.png"},{"id":69328192,"identity":"847c6337-67b4-4e93-a8a7-53bc800e8649","added_by":"auto","created_at":"2024-11-19 08:32:04","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":1590514,"visible":true,"origin":"","legend":"\u003cp\u003eTG-DTG profiles of the catalysts: fresh and used 18%Ce/WSAC, fresh and used 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC.\u003c/p\u003e","description":"","filename":"image7.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/5c9e7202fa915c9a380172a9.png"},{"id":69329382,"identity":"79b35f76-cb12-4098-95dc-f6ca60bbd5cc","added_by":"auto","created_at":"2024-11-19 08:48:04","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":863736,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of molar ratio of Cr/Ce on HCHO abatement over modified WSACs.\u003c/p\u003e","description":"","filename":"image8.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/086016cf265efb2d9524a42a.png"},{"id":69328182,"identity":"def6e630-d281-47fb-88b5-2e346d5f977e","added_by":"auto","created_at":"2024-11-19 08:32:04","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":792728,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of carrier materials on HCHO abatement over primaeval WSAC, WAC, SAC and modified WSACs.\u003c/p\u003e","description":"","filename":"image9.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/546107c69639f7cc5558eabf.png"},{"id":69328189,"identity":"bb4faba5-066a-4da7-a550-aa81f3239c14","added_by":"auto","created_at":"2024-11-19 08:32:04","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":1231292,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of active ingredients on HCHO abatement over primaeval WSAC and modified WSACs. (a) The performance of HCHO abatement over primaeval WSAC and 6%, 12%, 18%, 24%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSACs; (b) The performance of HCHO removal over primaeval WSAC, 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC, 18%Cr/WSAC and 18%Ce/WSAC. Reaction conditions: T = 80 - 400 °C, 6% O\u003csub\u003e2\u003c/sub\u003e, 200 ppm HCHO, N\u003csub\u003e2\u003c/sub\u003e as balance gas.\u003c/p\u003e","description":"","filename":"image10.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/5f44baed255b6802d88b632e.png"},{"id":69328185,"identity":"f28a8230-6595-4380-9889-51b8c867b389","added_by":"auto","created_at":"2024-11-19 08:32:04","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":1221268,"visible":true,"origin":"","legend":"\u003cp\u003eInfluence of O\u003csub\u003e2\u003c/sub\u003e concentration on HCHO abatement over 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC: Effect of O\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"image11.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/ecac941c5900e1e8ac80cc22.png"},{"id":69328195,"identity":"5c26696f-0d90-45d6-821f-d1f2abcd43e6","added_by":"auto","created_at":"2024-11-19 08:32:05","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":849344,"visible":true,"origin":"","legend":"\u003cp\u003eInfluence of H\u003csub\u003e2\u003c/sub\u003eO or SO\u003csub\u003e2\u003c/sub\u003e on HCHO abatement over 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC.\u003c/p\u003e","description":"","filename":"image12.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/f9a1e447708db8b1d8a31249.png"},{"id":69329060,"identity":"bc39f248-fde6-445b-aa0b-924d58838661","added_by":"auto","created_at":"2024-11-19 08:40:04","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":2392652,"visible":true,"origin":"","legend":"\u003cp\u003eStability and selectivity test of HCHO removal over 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC. (Reaction condition: 200 ppm HCHO, 6% O\u003csub\u003e2\u003c/sub\u003e, N\u003csub\u003e2\u003c/sub\u003e as balance gas, reaction temperature 280℃).\u003c/p\u003e","description":"","filename":"image13.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/28e865be69b19f52702789f8.png"},{"id":69328190,"identity":"daf65269-0937-4f11-aa30-87bc40899f88","added_by":"auto","created_at":"2024-11-19 08:32:04","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":1706044,"visible":true,"origin":"","legend":"\u003cp\u003eDynamic changes of in situ DRIFTS for the 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC sample in a flow of 200 ppm HCHO + 6% O\u003csub\u003e2\u003c/sub\u003e/N\u003csub\u003e2\u003c/sub\u003e at 280℃ or 200ppm HCHO+6%O\u003csub\u003e2\u003c/sub\u003e/N\u003csub\u003e2\u003c/sub\u003e+300ppm SO\u003csub\u003e2\u003c/sub\u003e or 200ppm HCHO+6% O\u003csub\u003e2\u003c/sub\u003e/N\u003csub\u003e2\u003c/sub\u003e+3%H\u003csub\u003e2\u003c/sub\u003eO+300ppm SO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"image14.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/88c32946122450c6837dae62.png"},{"id":69329058,"identity":"cc233f2b-03a0-4192-bce3-c169a81296be","added_by":"auto","created_at":"2024-11-19 08:40:04","extension":"png","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":2803628,"visible":true,"origin":"","legend":"\u003cp\u003eThe \u003ca href=\"javascript:;\"\u003eprobable\u003c/a\u003e removal mechanism of HCHO over 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC under 500ppm SO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e","description":"","filename":"image15.png","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/b204021a71dfd53c5698ef59.png"},{"id":73985702,"identity":"9caf2eb2-5395-42c6-8526-dfa2bce08a32","added_by":"auto","created_at":"2025-01-16 15:54:16","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":12922046,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5297317/v1/172be8fc-fa4b-45e6-8f14-ccc830d32e06.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Outstanding formaldehyde abatement performance and preferable resistance to SO 2 and H 2 O over CrO x -CeO x facilitated hierarchical porous biochars catalysts","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eVolatile organic compounds (VOCs) have sparked enormous attention worldwide due to their marked quantities and undesirable effects on the environment and human health\u003csup\u003e1\u003c/sup\u003e. As one of frequently encountered VOCs, HCHO was widely recognized as a potential threat in view of its grievous toxicity, carcinogenicity and teratogenicity\u003csup\u003e2\u003c/sup\u003e. To respond to these increasing environmental consciousness and rigorous emission regulations, multitudinous technologies for lessening HCHO emissions have been exploited, such as photocatalytic degradation, adsorption, biofiltration, condensation, plasma technology, and catalytic oxidation\u003csup\u003e3-6\u003c/sup\u003e. Among which, catalytic oxidation is considered to be a promising and resultful strategy to treat VOCs pollution on account of its unobjectionable cost, gratifying reliability and efficiency\u003csup\u003e7,8\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eIt is universally acknowledged that catalysts are the core factor in catalytic oxidation reactions. Among which mainstream catalysts are mainly divided into two types: supported precious metal catalysts and supported transition metal oxide catalysts\u003csup\u003e9\u003c/sup\u003e. Thereinto, diverse metal oxide supports such as CeO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e10\u003c/sup\u003e, TiO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e11\u003c/sup\u003e, Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e12\u003c/sup\u003e, MnO\u003csub\u003e2\u003c/sub\u003e, SiO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e13\u003c/sup\u003e and their composites including CeO\u003csub\u003e2\u003c/sub\u003e-TiO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e14\u003c/sup\u003e, InO\u003csub\u003e3\u003c/sub\u003e-SnO\u003csub\u003e2\u003c/sub\u003e, MnO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003e2\u003c/sub\u003e and CoO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e15\u003c/sup\u003e are popularly investigated for VOCs abatement inasmuch as their fine redox performance, outstanding dispersion, and the synergy effect between such supports and active metal oxides. Nevertheless, their widespread applications are impeded due to several defects like relatively expensive price, heterogeneous structure, low specific surface area, uncontrollable shape and size\u003csup\u003e16,17\u003c/sup\u003e. Equally, activated carbon is recognized as the most extensively adopted support of catalysts for VOCs abatement on account of its tunable price size, larger surface area, lower price, flexible application conditions and high hydrophobicity\u003csup\u003e1, 18\u003c/sup\u003e. However, the pore structure of conventional coal-based activated carbon possessed most micropores as well as slight mesopores and macropores, which led to the unsatisfactory adsorption and catalytic behaviors for VOCs abatement by its inconvenient internal diffusion and mass transfer\u003csup\u003e19\u003c/sup\u003e. In particular, the micropores of activated carbon might be chiefly semi-closed and bring trouble to the desorption of reactants and products\u003csup\u003e20\u003c/sup\u003e. Fortunately, differentiated from aforesaid commercial activated carbon, emerging hierarchical porous biochars were not mainly composed of micropores but a certain percentage of mesoporores and macropores, which greatly retrofitted the adsorption and catalytic performance for VOCs abatement through facilitating internal diffusion and mass transfer\u003csup\u003e21\u003c/sup\u003e. Meanwhile, lavish micropores greatly amplified the specific surface area, thus improving the adsorption capacity of small molecular gases, whereas mesopores and macropores could be employed as capacious rooms for active ingredients dispersion, providing channels for the transfer and mass diffusion\u003csup\u003e22,23\u003c/sup\u003e. In addition, mesopores and macropores could partly avoid SO\u003csub\u003e2\u003c/sub\u003e contaminating active ingredients\u003csup\u003e24\u003c/sup\u003e. Therefore, a new type of cheap and efficient hierarchical porous biochars possessed a great potential in the field of catalysis for VOCs abatement.\u003c/p\u003e\n\u003cp\u003eHowever, the abatement capacity of biochars toward VOCs is also restricted by its finite physicochemical property like finite activated sites\u003csup\u003e25\u003c/sup\u003e. According to reports, carbon-based materials loaded with metal oxides exhibited both higher adsorption and catalytic ability\u003csup\u003e1\u003c/sup\u003e. Therefore, biochars modified with metal oxides seem to be a potential and efficacious approach for improving their activity to a great extent\u003csup\u003e26\u003c/sup\u003e. As previously reported, some precious metal catalysts (Pt, Pd, Au, Rh, Ag, etc.) are tempting by their excellent activity for VOCs abatement, but they are commonly expensive and easily inactivated by poisoning or sintering\u003csup\u003e1,4\u003c/sup\u003e. On the contrary, transition metals have been extensively researched for their superior catalytic activity, readily availability, and low cost\u003csup\u003e27,28\u003c/sup\u003e. Thereinto, CeO\u003csub\u003ex\u003c/sub\u003e has attracted much publicity in catalysts for VOCs elimination by reason of abundant active oxygen species, high oxygen storage and release capacity, ample oxygen vacancies, and polyvalent transition\u003csup\u003e29,30\u003c/sup\u003e. Nevertheless, cerium-based catalysts were prone to suffer from SO\u003csub\u003e2\u003c/sub\u003e poisoning\u003csup\u003e31,32\u003c/sup\u003e. Universally acknowledged, the adulteration of CeO\u003csub\u003ex\u003c/sub\u003e with other metal oxides such as MoO\u003csub\u003ex\u0026nbsp;\u003c/sub\u003ecould produce synergistic effect, which was conducive to promoting VOCs oxidation and SO\u003csub\u003e2\u003c/sub\u003e tolerance\u003csup\u003e32-34\u003c/sup\u003e. As a kind of metal promoter and stabilizer, CrO\u003csub\u003ex\u003c/sub\u003e might exhibit preeminent catalytic activity as well as splendid SO\u003csub\u003e2\u003c/sub\u003e resistance in VOCs oxidation reactions\u003csup\u003e35-37\u003c/sup\u003e. It was demonstrated that CrO\u003csub\u003ex\u003c/sub\u003e could reduce the adsorption energy of SO\u003csub\u003e2\u003c/sub\u003e on the stable adsorption site of main active phases, thereby improving the SO\u003csub\u003e2\u003c/sub\u003e resistance of the catalyst\u003csup\u003e38\u003c/sup\u003e. Liu et al. found CeO\u003csub\u003e2\u003c/sub\u003e-TiO\u003csub\u003e2\u003c/sub\u003e doped with Cr catalysts behaved excellent SO\u003csub\u003e2\u003c/sub\u003e tolerance. Due to the synergistic effect of high oxygen storage-release Ce and Cr species, CrO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003e2\u003c/sub\u003e/MO\u003csub\u003ey\u003c/sub\u003e catalyst (M = Ti, V, Nb, Mo, W and La) had been reported to yield superior performance for Cl-VOCs oxidation\u003csup\u003e39\u003c/sup\u003e. Thus, it is sensible to extrapolate that CrO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003ex\u003c/sub\u003e facilitated hierarchical porous biochar catalysts might manifest satisfactory performance for VOCs abatement and SO\u003csub\u003e2\u003c/sub\u003e resistance.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTo the best of our understanding, few studies have focused on CrO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003ex\u003c/sub\u003e modifed biochars for HCHO abatement, in which the synergistic effect between CrO\u003csub\u003ex\u003c/sub\u003e and CeO\u003csub\u003ex\u003c/sub\u003e might contribute to the enhancement of catalytic performance and resistance to SO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO. Therefore, a series of tests are conducted to investigate the role of CrO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003ex\u003c/sub\u003e facilitated hierarchical porous biochar catalysts on the performance and resistance to SO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO for HCHO abatement in this work. A crowd of analytic techniques such as BET, XRD, XPS, SEM, H\u003csub\u003e2\u003c/sub\u003e-TPR, TG-DTG, and in situ DRIFTS were performed to uncover the structure-activity relationship of CrO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003ex\u003c/sub\u003e modifed biochars catalysts and their elimination mechanism of HCHO.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cp\u003e\u003cstrong\u003e2.1. Samples preparation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWalnuthusksand rice straws as biochar precursors were respectively gathered in Aksu City, Xinjiang Province, and Hengyang City, Hunan Province, China. Various biochars derived from individual walnut shell, separate solitary rice straw, and their union were defined as WAC, SAC, and WSAC, respectively. Firstly, the raw materials were rinsed with deionized water, then dried overnight at 105 \u0026deg;C, and screened for standby application after repeatedly dried-crushed to powder. The treated raw materials were activated through ZnCl\u003csub\u003e2\u003c/sub\u003e solution and then carbonized in a 700 \u0026deg;C electronic tube furnace under N\u003csub\u003e2\u003c/sub\u003e protection. The resulting powder was cooled and washed with deion water every 20 min for more than 50 times, and dried under a constant temperature drying box for 24 hours. In addition, Ce(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e\u0026bull;6H\u003csub\u003e2\u003c/sub\u003eO and Cr(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e\u0026bull;9H\u003csub\u003e2\u003c/sub\u003eO worked as the active ingredient precursors of CeO\u003csub\u003ex\u003c/sub\u003e and CrO\u003csub\u003ex\u003c/sub\u003e, respectively. Suitable WSAC was impregnated into the solution of active ingredient precursors for 24h. After impregnation, the samples were dried in a 60 \u0026deg;C drying chamber for 48h and calcined in the N\u003csub\u003e2\u003c/sub\u003e atmosphere in a 450 \u0026deg;C electronic tube furnace for 5h. The ultimately acquired samples were labeled as XCr\u003csub\u003ey\u003c/sub\u003eCe\u003csub\u003e1-y\u003c/sub\u003e/WSAC, in which y indicated the proportion of Cr in CrO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003e2\u003c/sub\u003e, and1-y delegated the proportion of Ce in CrO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003e2\u003c/sub\u003e,while X represented the total mass percentage of the metal oxides in the sample. Simultaneously, the individual Cr/WSAC and Ce/WSAC as well as WAC, SAC, and WSAC were also manufactured using the identical method for comparison.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2. Samples characterization\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe parameters of pore structure and BET surface area involved the samples were estimated through the micromeritics ASAP2460 specific surface and porosity analyzer (McMeretic Instruments, Shanghai). The surface structures and morphologies of specimens were scanned on electron microscopy (SEM) photographs, and then were analyzed on the MIRA4 analyzer (TESCAN, Czech Republic). The X-ray diffraction (XRD) results were gathered through a BRUKER D8 Advance (Bruker, Germany) X-ray diffraction device with the purpose of making a thorough inquiry into the dispersivity and component crystallinity of the samples. The H\u003csub\u003e2\u003c/sub\u003e-temperature programmed reduction (H\u003csub\u003e2\u003c/sub\u003e-TPR) was in progress by employing the Tianjin Xianquan TP-5080 automatic chemical adsorption instrument to emerge the redox behavior of specimens. The K-Alpha 250XI X-ray photoelectron spectrometer (America Thermo, USA) was applied to analyze the chemical properties and element chemical constituents of samples. The thermogravimetric (TG) analysis was carried out by employing a NETZSCH Thermal Analyzer (Germany) with a heating rate of 10 \u0026deg;C/min for investigating the sulfur resistance and thermal stability of fresh 18%Ce/WSAC, fresh 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC, used 18%Ce/WSAC, and used 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of samples was collected on a Nicolet iz10 (Thermo Fisher, USA).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3\u003c/strong\u003e\u003cstrong\u003e.\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;Experimental design and operation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAs emerged in Fig.1, the test device of the specimens purging HCHO principally consisted of three sections: a gas analyzer system, a simulated flue gas system, and a continuous flow fixed bed reactor system. The simulated flue gas (SFG) normally contained 200 ppm HCHO, 6%O\u003csub\u003e2\u003c/sub\u003e, and approximately 94%N\u003csub\u003e2\u003c/sub\u003e. The liquid HCHO was injected into the polytetrafluoroethylene tube wrapped by the temperature-dominated heating belt through a peristaltic pump and was heated to form a high-humidity HCHO vapor gas. Driven by 370 mL/min N\u003csub\u003e2\u003c/sub\u003e as the carrier gas, HCHO(g) was transferred to the condensing device for removing water vapour. At the same time, other gases entered into the fixed bed reactor together after being combined in multiple ways. What\u0026rsquo;s more, 0.3g sample was loaded into a quartz tube (inner diameter 10mm, length 1200mm) in a temperature-programmed tube furnace in each experiment. In each experiment, HCHO was beforehand introduced for 40 min to stabilize its concentration, then gradually increased the temperature from room temperature to 400 \u0026deg;C. The total flow rate of the simulated flue gas was constant at 500 mL/min, which was approximately equal to the gas hourly space velocity (GHSV) of 64000 h\u003csup\u003e-1\u003c/sup\u003e. In addition, a PGM7340 analyzer (RAE, USA) and a PGA-650 analyzer (Phymetrix, USA) were applied to separately gauge the HCHO and CO\u003csub\u003e2\u003c/sub\u003e concentrations at the inlet and outlet of the reactor. Concurrently, in order to dispel the interference factors of the instrument and the pipeline, relevant blank experiments were put into effect. The abatement efficiency of HCHO was labeled as R\u003csub\u003eHCHO\u003c/sub\u003e, and its mineralization rate was signed as S\u003csub\u003ecd\u003c/sub\u003e. Meanwhile, the inlet and outlet HCHO concentrations were tabbed as [HCHO]\u003csub\u003ein\u003c/sub\u003e and [HCHO]\u003csub\u003eout\u003c/sub\u003e, respectively. The outlet CO\u003csub\u003e2\u003c/sub\u003e concentration in blank test was labeled as [CO\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003eout1\u003c/sub\u003e, simultaneously, [CO\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003eout2\u003c/sub\u003e represented the outlet CO\u003csub\u003e2\u003c/sub\u003e concentration (ppm) in the formal tests. R\u003csub\u003eHCHO\u003c/sub\u003e and S\u003csub\u003ecd\u003c/sub\u003e were respectively defined as the following formulas:\u003c/p\u003e\n\u003cp\u003e\u003cimg 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\"\u003e\u003c/p\u003e\n\u003cp\u003e[Fig.1]\u003c/p\u003e\n\u003cp\u003eFor the sake of reducing the error and guaranteeing the accuracy of the experimental results, R\u003csub\u003eHCHO\u003c/sub\u003e and S\u003csub\u003ecd\u003c/sub\u003e had taken the average value of three parallel tests, and their relative errors were controlled within 5%.\u003c/p\u003e"},{"header":"3. Results and discussion","content":"\u003cp\u003e\u003cstrong\u003e3.1. Characterization of samples\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.1.1. BET analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe textural and structural properties of primaeval and facilitated samples were given in Table 1. Notably, primaeval WSAC owned the largest BET surface area (729.667m\u003csup\u003e2\u003c/sup\u003e/g) and the largest total pore volume (0.376cm\u003csup\u003e3\u003c/sup\u003e/g). Nevertheless, both the BET specific surface areas and total pore volumes of facilitated WSAC samples gradually declined with the enhancement loading value of bimetallic oxides. Likewise, the micopore surface areas behaved the same descending order except for\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WAC.\u0026nbsp;That appearance could be explained by the fact that loading metal oxides inevitably led to the blockage of partial carrier pores, and the undesirable metal oxides aggregations became more serious with the excessive loading of metal oxides\u003csup\u003e40\u003c/sup\u003e. The above-mentioned results were in perfect accordance with XRD and SEM analyses. Interestingly, the BET specific surface areas and pore characteristic parameters of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC seemed neutralized by 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WAC and 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/SAC. In addition to the\u0026nbsp;BET specific surface area, the amount and ratio of micro/meso/macropores were also crucial for mass transfer routes and available adsorption/catalytic sites, which exhibited significant effect on its performance\u003csup\u003e19,41\u003c/sup\u003e. With regard to the section of 3.2.2, it was reasonable to speculate that the hierarchical porous structure of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC might embody appropriate ratio of micro/meso/macropores and benefit the mass transfer and diffusion of reactants and products, which was responsible for the highest catalytic activities of HCHO elimination. Moreover, the N\u003csub\u003e2\u003c/sub\u003e adsorption/desorption isotherms and corresponding pore size distribution curves of as-prepared samples were depicted in Fig.2a and Fig.2b, respectively. All samples shared the typical IV isotherms with H3 hysteresis loops, which was the inherent characteristic of slit-like mesopores\u003csup\u003e42\u003c/sup\u003e. It was readily acknowledged that slit-like porous structure was propitious to the expeditious mass transfer of reactants and intermediates, which could exert promotional effect on catalytic reactions\u003csup\u003e43\u003c/sup\u003e. Howbeit, it was worth mentioning that the BET surface areas and pore properties of as-prepared samples were not in line with their catalytic performances, indicating that the BET surface areas and pore properties were not the decisive element for HCHO abatement in this work.\u003c/p\u003e\n\u003cp\u003e[Table.1]\u003c/p\u003e\n\u003cp\u003e[Fig.2]\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.1.2. SEM and EDX analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe SEM images of primaeval WSAC and facilitated WSACs were demonstrated in Fig.3. The shady zones corresponded to carbon enriched areas, whereas light zones manifested the presence of CrO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003ex\u003c/sub\u003e. The primitive surface characteristics of primaeval WSAC were \u0026nbsp;markedly changed after loading metal oxides, which mainly scattered on the surface of facilitated WSACs\u003csup\u003e43\u003c/sup\u003e. It was clearly observed that a little agglomerates located in 6%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC. However, superfluous shady areas meant that the surfaces of 6%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC were not fully utilized. Generally speaking, better catalytic activity was archly depended upon more dispersed active metal oxides\u003csup\u003e44\u003c/sup\u003e.\u0026nbsp;With regard to\u0026nbsp;12%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC, more metal oxides appeared on available areas and more agglomerates were detected. It was noted that most surface areas of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC were highly covered by CrO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003ex\u003c/sub\u003e, and only accredited agglomerates were observed, whereas substantial agglomerates existed in 24%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC. Thus, overfull metal oxides inevitably contributed to more serious agglomerates that might hide the pores and catalytic active sites, which was unfavourable for HCHO abatement and the economy,\u0026nbsp;which was in good agreement with BET results\u003csup\u003e45-47\u003c/sup\u003e. Furthermore, the sketchy elemental ratio of Cr and Ce of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC was gauged by EDX, where the detection point was marked as \u0026ldquo;spectrum\u0026rdquo; in Fig.3d. As illustrated in Fig.3f, the Cr/Ce atomic ratio was 2.01, which was approximately equal to double the Cr/Ce atomic ratio on 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC. The observation hinted that CeO\u003csub\u003ex\u003c/sub\u003e acquired a better dispersion than that of CrO\u003csub\u003ex\u003c/sub\u003e.\u003c/p\u003e\n\u003cp\u003e[Fig.3]\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.1.3. H\u003csub\u003e2\u003c/sub\u003e-TPR analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe redox capacities of primaeval WSAC and facilitated WSACs were evaluated\u0026nbsp;by\u0026nbsp;H\u003csub\u003e2\u003c/sub\u003e-TPR and interrelated results were unfolded in\u0026nbsp;Fig.4.\u0026nbsp;The\u0026nbsp;obvious\u0026nbsp;reduction peaks centred\u0026nbsp;at\u0026nbsp;421 \u0026deg;C and 612 \u0026deg;C in primaeval WSAC were respectively attributed to the deoxidization of surface adsorbed oxygen and gasification of WSAC\u0026nbsp;matrix\u003csup\u003e19\u003c/sup\u003e, which were also detected in other\u0026nbsp;facilitated\u0026nbsp;samples.\u0026nbsp;For 18%Cr/WSAC,\u0026nbsp;two\u0026nbsp;additional peaks observed at 300 \u0026deg;C and 510 \u0026deg;C\u0026nbsp;could be\u0026nbsp;referred to\u0026nbsp;the consecutive reduction of Cr\u003csup\u003e6+\u003c/sup\u003e to Cr\u003csup\u003e3+\u0026nbsp;\u003c/sup\u003eand the reduction of either surface/sub-surface oxygen in small Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e particles\u003csup\u003e35,48\u003c/sup\u003e.\u0026nbsp;With regard to 18%Ce/WSAC, new reduction peaks emerged at 330 \u0026deg;C and 580 \u0026deg;C, the former\u0026nbsp;was attributed to\u0026nbsp;the surface oxygen revivification of CeO\u003csub\u003e2\u003c/sub\u003e, while the latter was\u0026nbsp;ascribed to\u0026nbsp;the bulk oxygen depletion in structure of CeO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e49,50\u003c/sup\u003e.\u0026nbsp;Obviously, compared with primaeval WSAC, the reduction peaks in facilitated WSACs shifted towards lower temperature with the introduction of either CrO\u003csub\u003ex\u003c/sub\u003e or CeO\u003csub\u003ex\u003c/sub\u003e, manifesting that the presence of SMSI (Strong-Metal-Support-Interaction) between active ingredients and WSAC support\u003csup\u003e51\u003c/sup\u003e. In terms of\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC, two peaks\u0026nbsp;appeared at\u0026nbsp;260 \u0026deg;C and 345 \u0026deg;C were put down to the reduction of Cr\u003csup\u003e6+52\u003c/sup\u003e. Compared with monometallic catalysts,\u0026nbsp;it was clearly seen that the reduction peaks of\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC shifted to lower temperatures, attesting\u0026nbsp;it generated better redox ability than that of 18%Cr/WSAC and 18%Ce/WSAC\u003csup\u003e44\u003c/sup\u003e. Such observations\u0026nbsp;could be correlated with the synergistic effects between CrO\u003csub\u003ex\u003c/sub\u003e and CeO\u003csub\u003ex\u003c/sub\u003e, in which the couples of Cr\u003csup\u003e6+\u003c/sup\u003e/Cr\u003csup\u003e3+\u003c/sup\u003e and Ce\u003csup\u003e4+\u003c/sup\u003e/Ce\u003csup\u003e3+\u003c/sup\u003e facilitated each other to reduce the energy required for the electronic transfer or the generation of more surface oxygen vacancies, thus notably boosting oxygen mobility reinforcement or reactants activation\u003csup\u003e53\u003c/sup\u003e.\u0026nbsp;On the other aspect, the hierarchical porous structure of the carrier was more\u0026nbsp;conducive to\u0026nbsp;the dispersion of active components\u003csup\u003e40\u003c/sup\u003e. Therefore, we presumed that 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC could offer desirable catalytic performance in virtue of the synergistic effect between CrO\u003csub\u003ex\u003c/sub\u003e and\u0026nbsp;CeO\u003csub\u003ex\u003c/sub\u003eand the high dispersion of active metal oxides stemmed from hierarchical pores carrier.\u003c/p\u003e\n\u003cp\u003e[Fig.4]\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.1.4. XRD analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe XRD pictorial of\u0026nbsp;primaeval WSAC and facilitated WSACs\u0026nbsp;were portrayed in Fig.5. It could be seen that seven peaks at 2\u0026theta;\u0026nbsp;= 21.96\u0026deg;, 26.60\u0026deg;, 31.48\u0026deg;, 33.94\u0026deg;, 38.76\u0026deg;, 44.58\u0026deg; and 48.84\u0026deg; were detected at\u0026nbsp;primaeval\u0026nbsp;WSAC,\u0026nbsp;wherein the peaks\u0026nbsp;at 2\u0026theta; = 26.60\u0026deg; and 44.58\u0026deg; were in response to\u0026nbsp;carbon matrix\u0026nbsp;(JCPDS no. 25-0284)\u003csup\u003e21,27\u003c/sup\u003e, while extra peaks at 21.96\u0026deg;, 31.48\u0026deg;, 33.94\u0026deg;, 38.76\u0026deg; and 48.84\u0026deg; were in line with SiO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e16,44,51\u003c/sup\u003e.\u0026nbsp;Interestingly, they both attenuated with doping CrO\u003csub\u003ex\u003c/sub\u003e or CeO\u003csub\u003e2\u003c/sub\u003e, inferring that the SMSI might exist between metal oxides and WSAC\u003csup\u003e19\u003c/sup\u003e, as demonstrated in H\u003csub\u003e2\u003c/sub\u003e-TPR, SEM and XPS analyses. As regards 18%Ce/WSAC, the intrinsic peaks at 2\u0026theta;\u0026nbsp;= 29.46\u0026deg;,\u0026nbsp;34.23\u0026deg; and\u0026nbsp;48.65\u0026deg; represented the existence of CeO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e54,55\u003c/sup\u003e.\u0026nbsp;Additionally,\u0026nbsp;with regard to\u0026nbsp;18%Cr/WSAC, the inherent peaks at 2\u0026theta;\u0026nbsp;= 24.63\u0026deg;, 33.65\u0026deg;, 36.27\u0026deg; and 65.21\u0026deg; were associated with the presence of Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (JCPDS No. 82-1484)\u003csup\u003e38,56,57\u003c/sup\u003e. Nevertheless, no signature diffraction peaks ascribed to Cr and Ce species were\u0026nbsp;discovered in XCr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSACs\u0026nbsp;compared with 18%Ce/WSAC and 18%Cr/WSAC,\u0026nbsp;revealing\u0026nbsp;that\u0026nbsp;the interaction between Cr and Ce was propitious to generating smaller amorphous surface species\u003csup\u003e58\u003c/sup\u003e, which\u0026nbsp;might promote surface oxygen vacancies and\u0026nbsp;be the presumable justification of\u0026nbsp;accelerating\u0026nbsp;catalytic activity and SO\u003csub\u003e2\u003c/sub\u003e resistance.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp;[Fig.5]\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.1.5. XPS analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eXPS was conducted to explore the chemical valence and composition of the elements on the surface of primaeval WSAC, fresh and used facilitated WSAC samples. The XPS spectra of O 1s, C 1s, Ce 3d and Cr 2p were demonstrated in Fig.6. As for primaeval WSAC, the three obvious sub-peaks with binding energy at 525.60-530.21 eV, 530.41-531.75 eV, 532.03-535.58 eV were observed in these specimens (Fig.6a), which could be attributable to lattice oxygen (O\u003csub\u003e\u0026alpha;\u003c/sub\u003e), chemically adsorbed oxygen, oxygen vacancies or hydroxyl groups (O\u003csub\u003e\u0026beta;\u003c/sub\u003e), and adsorbed water species (O\u003csub\u003e\u0026gamma;\u003c/sub\u003e), respectively\u003csup\u003e59\u003c/sup\u003e. According to reports, surface adsorbed oxygen (O\u003csub\u003e\u0026beta;\u003c/sub\u003e) was more mobile than that of lattice oxygen (O\u003csub\u003e\u0026alpha;\u003c/sub\u003e)\u003csup\u003e60\u003c/sup\u003e. Meanwhile, according to the Marsvan-Krevelen mechanism, O\u003csub\u003e\u0026beta;\u003c/sub\u003e occupied an extremely significant position in the catalytic oxidation of VOCs, and it could complement O\u003csub\u003e\u0026alpha;\u003c/sub\u003e through a suite of migrations and conversions\u003csup\u003e61\u003c/sup\u003e. Apparently, O\u003csub\u003e\u0026alpha;\u003c/sub\u003e was visible on facilitated WSAC samples compared with primaeval WSAC, demonstrating that the introduction of metal oxides contributed to the formation of O\u003csub\u003e\u0026alpha;\u003c/sub\u003e\u003csup\u003e19\u003c/sup\u003e. As an oxygen storage reservoir, O\u003csub\u003e\u0026alpha;\u003c/sub\u003e and the oxygen-containing functional groups of the carrier could replenish O\u003csub\u003e\u0026beta;\u003c/sub\u003e, thereby enhancing the activity of surface oxygen\u003csup\u003e51\u003c/sup\u003e. Furthermore, the O\u003csub\u003e\u0026beta;\u003c/sub\u003e content of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC was significantly higher than that of 18%Cr/WSAC and 18%Ce/WSAC, revealing that more surface adsorbed oxygen engendered as a result of the synergistic effect between CrO\u003csub\u003ex\u003c/sub\u003e and CeO\u003csub\u003ex\u003c/sub\u003e. What\u0026rsquo;s more, the ratios of O\u003csub\u003e\u0026alpha;\u003c/sub\u003e, O\u003csub\u003e\u0026beta;\u003c/sub\u003e, and O\u003csub\u003e\u0026gamma;\u003c/sub\u003e in used 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC were different from fresh 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC. The proportion of O\u003csub\u003e\u0026beta;\u003c/sub\u003e declined from 73.9% to 59.2%, while O\u003csub\u003e\u0026gamma;\u003c/sub\u003e and O\u003csub\u003e\u0026alpha;\u003c/sub\u003e received an ascension, which exposed that O\u003csub\u003e\u0026beta;\u003c/sub\u003e participated in the reactions and was consumed in the processes. Therefore, we speculated that abundant O\u003csub\u003e\u0026beta;\u003c/sub\u003e on the surface of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC might contribute to the well-pleasing catalytic activity for HCHO abatement.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e[Fig.6]\u003c/p\u003e\n\u003cp\u003eThe XPS spectra of C 1s were displayed in Fig.6b, which could be deconvoluted into five peaks. The peaks located at 282.92-284.02 eV, 284.12-285.11 eV, 285.51-287.61 eV were respectively in association with graphitic carbons (C\u0026ndash;C/H), carbon emerging in phenolic, ether groups (C-O) and alcohol, while other peaks situated at 287.85-288.88 eV, 289.03-294.11 eV corresponded to carbonyl groups (C=O), ester groups (COOH) or carboxyl and \u0026pi;-\u0026pi;* transitions in aromatic rings (\u0026pi;-\u0026pi;)\u003csup\u003e62,63\u003c/sup\u003e. As shown, the sharp and huge peaks of primaeval WSAC illustrated that the hierarchical\u0026nbsp;porous carrier held extremely abundant surface functional groups. Nevertheless, once bimetallic metal oxides were loaded on WSAC, most aforementioned peaks slightly shifted toward lower binding energies except for C-C/H. That observations might be explained by that the synergistic effect between Cr and Ce oxides elevated the stability of surface oxygen-containing functional groups\u003csup\u003e50\u003c/sup\u003e. Additionally, with the adjunction of active components, the proportion of C-O in all facilitated samples declined significantly, while the ratios of C-C/H and COOH increased. The former could come down to C-O desorption provoked by high-temperature calcination under N\u003csub\u003e2\u003c/sub\u003e atmosphere, and the latter was probably affiliated with the loading of nitrate precursors\u003csup\u003e64\u003c/sup\u003e. For both used and fresh 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC, the overall oxygen-containing functional groups and C-O of used samples abated, which was probably owing to the oxidation of C-O by active oxygen species in the process of HCHO abatement\u003csup\u003e65\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eThe XPS spectra of Cr 2p (Fig.6c) were resolved into four characteristic peaks situated at 586.66-594.11 eV, 577.11-580.22 eV, 580.52-586.31 eV, and 575.32-576.21 eV, the former two peaks pertained to Cr\u003csup\u003e6+\u003c/sup\u003e, and the other ones could be distinguished as Cr\u003csup\u003e3+\u003c/sup\u003e, signifying that Cr existed mainly in two valence states in all samples\u003csup\u003e66\u003c/sup\u003e. Compared with 18%Cr/WSAC, the proportion of peaks that had a bearing on Cr\u003csup\u003e6+\u003c/sup\u003e greatly declined after adding CeO\u003csub\u003ex\u003c/sub\u003e, which was perhaps that high-valent chromium taken over electrons from low-valent cerium. Compared with 18%Cr/WSAC, the Cr\u003csup\u003e6+\u003c/sup\u003e percentage of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC increased from 20.4% to 35.8%, while the Cr\u003csup\u003e3+\u0026nbsp;\u003c/sup\u003eratio of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC decreased from 79.6% to 64.2%. It was affirmed that the coexistence of multiple oxidative states of Cr ions was beneficial to the oxidation of VOCs\u003csup\u003e67,68\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eThe XPS spectra of Ce 3d were deconvoluted into eight peaks (Fig.6d), therein two peaks situated at 887.11-889.25 eV and 905.62-911.11 eV corresponded to Ce\u003csup\u003e3+\u003c/sup\u003e species, and other peaks centered at 884.12-884.21 eV, 893.05-895.23 eV, 900-900.41 eV, 903.42-903.65 eV, 914.81-917.51 eV, and 919.94-920.05 eV were ascribed to Ce\u003csup\u003e4+\u003c/sup\u003e species\u003csup\u003e37,69\u003c/sup\u003e. Differed from fresh 18%Ce/WSAC, the relevant peak intensities of Ce\u003csup\u003e3+\u003c/sup\u003e of fresh 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC attenuated while the ratio of Ce\u003csup\u003e4+\u003c/sup\u003e/Ce\u003csup\u003e3+\u003c/sup\u003e boosted. Simultaneously, the total peak signal (Ce\u003csup\u003e3+\u003c/sup\u003e+Ce\u003csup\u003e4+\u003c/sup\u003e) of the latter significantly ascended, promulgating that a redox cycle of Cr\u003csup\u003e6+\u003c/sup\u003e+Ce\u003csup\u003e3+\u003c/sup\u003e\u0026harr;Cr\u003csup\u003e3+\u003c/sup\u003e+Ce\u003csup\u003e4+\u003c/sup\u003e between CrO\u003csub\u003ex\u003c/sub\u003e and CeO\u003csub\u003e2\u003c/sub\u003e emerged and the introduction of Cr accelerated the transition of Ce into high valence states\u003csup\u003e69\u003c/sup\u003e. The higher Ce\u003csup\u003e4+\u003c/sup\u003e/Ce\u003csup\u003e3+\u003c/sup\u003e enhanced the conversion of oxidation states between high-valent cerium and low-valent cerium, resulting in the higher oxygen release and storage capacity, which was beneficial to the catalytic of HCHO\u003csup\u003e70\u003c/sup\u003e. For fresh 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC, it could be clearly surveyed that the ratio of Ce\u003csup\u003e3+\u003c/sup\u003e hoisted in the comparison of used 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC, interpreting a portion of Ce\u003csup\u003e4+\u003c/sup\u003e was consumed in the reactions. According to literature reports, high-valent Ce ions tended to be deactivated by preferentially reacting with SO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e71\u003c/sup\u003e, however, Ce\u003csup\u003e4+\u003c/sup\u003e still maintained a high proportion (58.5%) in used samples, which was presumably the result of that Cr reduced the adsorption energy of SO\u003csub\u003e2\u003c/sub\u003e on the most stable adsorption site of CeO\u003csub\u003e2\u003c/sub\u003e, thereby inhibiting the sulfation of Ce\u003csup\u003e4+\u003c/sup\u003e and elevating SO\u003csub\u003e2\u0026nbsp;\u003c/sub\u003eresistance\u003csup\u003e38\u003c/sup\u003e. Therefore, affluent high-valent Ce and Cr on 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC advanced the efficient abatement of HCHO and boosted its excellent SO\u003csub\u003e2\u003c/sub\u003e resistance.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.1.6. TG-DTG\u003c/strong\u003e\u003cstrong\u003eanalysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo further characterize the type and content of sulfate compounds formed on\u0026nbsp;used samples, the TG-DTG curves of\u0026nbsp;fresh 18%Ce/WSAC, fresh 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC, used 18%Ce/WSAC, and used 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC\u0026nbsp;were revealed. In Fig.7, all aforementioned samples presented obvious weight loss below 200\u0026nbsp;\u0026deg;C, which might be owing to the evaporation of adsorbed water on the surfaces\u003csup\u003e72\u003c/sup\u003e. For used 18%Ce/WSAC (Fig.7b), the mass wastage was classified into three stages. The first step (30~200\u0026nbsp;\u0026deg;C) was related to the water desorption. What\u0026apos;s more,\u0026nbsp;the second step about\u0026nbsp;the weight loss within\u0026nbsp;200~500\u0026nbsp;\u0026deg;C\u0026nbsp;could become down to the decomposition of precursors,\u0026nbsp;cellulose, or lignin\u003csup\u003e73\u003c/sup\u003e. The third step in the high-temperature region above 450\u0026nbsp;\u0026deg;C\u0026nbsp;could be attributed to the disintegration of Ce(SO\u003csub\u003e4\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e into CeO\u003csub\u003e2\u003c/sub\u003e and SO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e37\u003c/sup\u003e. Moreover, the mass wastage of used 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC could been divided into four stages. The first step (50~210\u0026nbsp;\u0026deg;C) was ascribed to the water evaporation. Similarly,\u0026nbsp;the second step (210~510\u0026nbsp;\u0026deg;C) was\u0026nbsp;also\u0026nbsp;resolved into the factorization of precursors,\u0026nbsp;cellulose, or lignin\u003csup\u003e73\u003c/sup\u003e. The third step (510~700\u0026nbsp;\u0026deg;C) and the fourth step (700~1000\u0026nbsp;\u0026deg;C) situated in the high-temperature extent primarily pertained to the disintegration of Cr\u003csub\u003e2\u003c/sub\u003e(SO\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e and Ce(SO\u003csub\u003e2\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e, respectively\u003csup\u003e37,66\u003c/sup\u003e. Simultaneously, compared with used 18%Ce/WSAC, the lesser loss was disclosed in\u0026nbsp;used\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC, indicating that the doping of Cr enlarged thermal stability of the sample to a certain extent. In addition, the mass-loss rate of used 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC was significantly lower than that of used 18%Ce/WSAC, which exposed that the synergistic effect between CrO\u003csub\u003ex\u003c/sub\u003e and CeO\u003csub\u003e2\u003c/sub\u003e reduced the engendering and coverage of surface sulfates, accordingly significantly increasing the SO\u003csub\u003e2\u003c/sub\u003e tolerance of such catalyst\u003csup\u003e37\u003c/sup\u003e.\u0026nbsp;Combined with above analyses, we have plenitudinous reasons to believe that 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC has excellent SO\u003csub\u003e2\u003c/sub\u003e resistance.\u003c/p\u003e\n\u003cp\u003e[Fig.7]\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2. The performance of samples\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.1. Effect of molar ratio of Cr/Ce\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIt was generally appreciated that the quantity and distribution of surface adsorbed oxygen, active site and surface area of bimetallic catalysts were in close correlation with the bimetallic molar ratio\u003csup\u003e66\u003c/sup\u003e. Hence, the influence of the molar ratio of Cr/Ce of 18%Cr\u003csub\u003ey\u003c/sub\u003eCe\u003csub\u003e1-y\u003c/sub\u003e/WSACs on R\u003csub\u003eHCHO\u003c/sub\u003e was explored and the test datum were presented in Fig.8. Similarly, all 18%Cr\u003csub\u003ey\u003c/sub\u003eCe\u003csub\u003e1-y\u003c/sub\u003e/WSACs had broadly analogous performance trends, in which R\u003csub\u003eHCHO\u003c/sub\u003e first enhanced significantly with increasing reaction temperature and whereafter R\u003csub\u003eHCHO\u003c/sub\u003e expressed a slightly decreasing trend once the reaction temperature continuously augmented to a certain extent. The former might be because elevating the reaction temperature could furnish more kinetic energy, which was conducive to the adsorption and oxidation of HCHO\u003csup\u003e54\u003c/sup\u003e. At the same time, there could be a couple of reasons for the decline of R\u003csub\u003eHCHO\u003c/sub\u003e at high temperatures. High temperature inhibited the adsorption of HCHO, especially physical adsorption, which was one interpretation for the high-temperature decline of R\u003csub\u003eHCHO\u003c/sub\u003e\u003csup\u003e22,74\u003c/sup\u003e. The other reason might be put down to that the structure of WSAC was destructed on account of that the carbon matrix could be catalyzed into CO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO by active metal oxides under high temperature\u003csup\u003e19\u003c/sup\u003e. On balance, 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSACs behaved the best performance across the entire reaction temperature range. The superior appearance might be related to the excellent physicochemical properties caused by the synergistic action of suitable Cr and Ce oxides, forming rich active sites and large HCHO adsorption and oxidation interfaces, thereby boosting the abatement performance of HCHO\u003csup\u003e37,57\u003c/sup\u003e. Certainly, moderate CeO\u003csub\u003ex\u003c/sub\u003e could inhibit the agglomeration of CrO\u003csub\u003ex\u003c/sub\u003e, avoiding the loss of some accessible active sites\u003csup\u003e38\u003c/sup\u003e. Eventually, the optimal Cr/Ce ratio of 1:1 was used in subsequent studies.\u003c/p\u003e\n\u003cp\u003e[Fig.8]\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.2. Effect of carrier material \u0026nbsp;\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe carriers made from various materials typically expressed unique surface oxygen functional groups and pore structure, which affected the abatement performance of the samples by impacting the dispersion of active metal oxides and the mass transfer and timely diffusion of reactants\u003csup\u003e75\u003c/sup\u003e. Therefore, the possible effects of various carriers from different raw materials on HCHO abatement were disclosed in Fig.9. Obviously,\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC\u0026nbsp;behaved middle\u0026nbsp;R\u003csub\u003eHCHO\u003c/sub\u003e between\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/SAC\u0026nbsp;and 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WAC at 80~160 \u0026deg;C, and then presented best R\u003csub\u003eHCHO\u003c/sub\u003e with further ascending reaction temperature, which was complied with the results of in situ DRIFTS that initially\u0026nbsp;adsorption\u0026nbsp;dominated for\u0026nbsp;HCHO\u0026nbsp;abatement at low temperature and it would be gradually superseded by\u0026nbsp;catalytic oxidation\u0026nbsp;at high temperature\u003csup\u003e19\u003c/sup\u003e. In addition, excellent HCHO catalytic oxidation performance of\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC at 160~400 \u0026deg;C might be responsible by that WSAC carrier obtained more befitting proportion of micropores, mesopores and macropores, and such hierarchical porous structure immensely facilitated the mass transfer and diffusion of reactants and offspring molecules\u003csup\u003e51\u003c/sup\u003e. Furthermore, all the samples unveiled a debasing R\u003csub\u003eHCHO\u003c/sub\u003e trend after 280 \u0026deg;C, and\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC descended lower than that of\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WAC and\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/SAC. The appearance could be illustrated by that the active centres and pore structures of samples were ruined by high temperature\u003csup\u003e19\u003c/sup\u003e, and\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC evinced superior thermal stability. Combined with BET analyses, the physicochemical properties of\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC seemed to be a fantastic neutralization of\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WAC and\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/SAC. Compared with them, although\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC possessed no optimal BET surface areas and pore properties, its hierarchical porous structure could facilitate mass transfer and the diffusion of gaseous reactants and products, thus enhancing\u0026nbsp;HCHO\u0026nbsp;adsorption and oxidation. Besides, the\u0026nbsp;suitable\u0026nbsp;hierarchical porous structures\u0026nbsp;of\u0026nbsp;18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC\u0026nbsp;might be also partly beneficial\u0026nbsp;for its preeminent\u0026nbsp;thermal stability\u0026nbsp;under high temperature conditions.\u003c/p\u003e\n\u003cp\u003e[Fig.9]\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.3. Effect of active ingredients\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe dispersion, crystallinity, aggregation and redox property of active metal oxides were critical factors to resolve catalytic activity of samples, which were usually affected by the content and composition of active ingredients\u003csup\u003e15\u003c/sup\u003e. As signified in Fig.10, R\u003csub\u003eHCHO\u003c/sub\u003e of Cr or Ce solely facilitated samples evinced an apparent ascent over against with that of primaeval WSAC, implying the introduction of active ingredients vigorously boosted HCHO abatement. Especially, R\u003csub\u003eHCHO\u003c/sub\u003e of facilitated samples shown a conspicuous enlargement trend with the growth of loading value of CrCe oxides and reaction temperature, and soon afterwards exhibited a descending appearance with further raising reaction temperature. Fortunately, 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC unfolded the uppermost catalytic activity of 99.2% at 280 \u0026deg;C, which was possibly connected to the good dispersion of metal oxides and more oxygen vacancies, which were confirmed by SEM results. Integrated with XPS analysis, the exceptional reducibility of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC could heighten the activity and mobility of lattice oxygen, ultimately accelerating HCHO oxidation\u003csup\u003e59\u003c/sup\u003e. In addition, Fig.10b certificated that 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC exhibited better R\u003csub\u003eHCHO\u003c/sub\u003e than that of 18%Cr/WSAC and 18%Ce/WSAC. The phenomenon could be inferred as the synergistic effect between CrO\u003csub\u003ex\u003c/sub\u003e and CeO\u003csub\u003ex\u003c/sub\u003e,which improved their dispersion, enhanced the amount of oxygen vacancies and perfected active oxygen mobility, thereby boosting the reducibility of Cr and Ce co-facilitated sample\u003csup\u003e44\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e[Fig.10]\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.4.\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eEffect of O\u003csub\u003e2\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAs one of pivotal gas components in industrial flue gas, O\u003csub\u003e2\u003c/sub\u003e occupied a momentous position in HCHO oxidation\u003csup\u003e59\u003c/sup\u003e. As literature reported, minuscule oxygen content easily debased the catalytic oxidation activity of catalysts\u003csup\u003e19\u003c/sup\u003e. However, as seen in Fig.11, 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC still preserved a high activity (R\u003csub\u003eHCHO\u003c/sub\u003e=86.1%) without oxygen (SFG-6%O\u003csub\u003e2\u003c/sub\u003e), which could be rooted in the residual lattice oxygen (O\u003csub\u003e\u0026alpha;\u003c/sub\u003e) and surface active oxygen (O\u003csub\u003e\u0026beta;\u003c/sub\u003e) could timely participate in the HCHO oxidation reactions, and this was in well accordance with XPS analysis. Compared with SFG-6%O\u003csub\u003e2\u003c/sub\u003e, the substantially ascending R\u003csub\u003eHCHO\u0026nbsp;\u003c/sub\u003e(97.2%) under SFG condition stated clearly that O\u003csub\u003e2\u003c/sub\u003e had the positive effect on R\u003csub\u003eHCHO\u003c/sub\u003e, whichwasattributed to that the pull-in of gas-phase oxygen supplemented consumed lattice oxygen and surface adsorbed oxygen\u003csup\u003e19\u003c/sup\u003e. With the further enlargement of O\u003csub\u003e2\u0026nbsp;\u003c/sub\u003e(SFG+6%O\u003csub\u003e2\u003c/sub\u003e), only a slight exaltation of R\u003csub\u003eHCHO\u003c/sub\u003e was observed (R\u003csub\u003eHCHO\u003c/sub\u003e=99.9%), implying that the O\u003csub\u003e2\u003c/sub\u003e content in the actual flue gas was sufficient to satisfy HCHO oxidation.\u003c/p\u003e\n\u003cp\u003e[Fig.11]\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.5. Effect of SO\u003csub\u003e2\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAs one of significant interfering gas components in industrial flue gas, SO\u003csub\u003e2\u003c/sub\u003e inevitably affected the R\u003csub\u003eHCHO\u003c/sub\u003e of the samples\u003csup\u003e69\u003c/sup\u003e. In Fig.12 (SO\u003csub\u003e2\u003c/sub\u003e), a slight decrease was detected for the HCHO abatement performance of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC when 300 ppm SO\u003csub\u003e2\u003c/sub\u003e was added into the SFG, while more and more obvious decline could be observed with increasing SO\u003csub\u003e2\u003c/sub\u003e concentration. The above phenomenon could be attributed to two possible causes: on the one hand, a certain degree of competitive adsorption existed between SO\u003csub\u003e2\u003c/sub\u003e and HCHO due to various polarity\u003csup\u003e51\u003c/sup\u003e. On the other hand, the active phase was poisoned and inactivated by SO\u003csub\u003e2\u003c/sub\u003e reacting with metal oxides, and such generating metal sulfides might block some pores and overlay partial active sites, thus interrupting the redox cycling of HCHO oxidation\u003csup\u003e76\u003c/sup\u003e. In addition, the satisfactory catalytic activity of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC at high SO\u003csub\u003e2\u0026nbsp;\u003c/sub\u003econcentration indicated that 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC possessed fine SO\u003csub\u003e2\u003c/sub\u003e resistance, which might be interpreted by that appropriate amount doping of CrO\u003csub\u003ex\u003c/sub\u003e effectively defended the active center of Ce species. Simultaneously, integrated with aforementioned characterization analyses, the hierarchical porous structure of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC further elevated SO\u003csub\u003e2\u003c/sub\u003e tolerance\u003csup\u003e77,78\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e[Fig.12]\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.6. Effect of H\u003csub\u003e2\u003c/sub\u003eO and SO\u003csub\u003e2\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe presence of water vapor in industrial flue gas frequently interfered the catalytic performance of catalysts. In general, the R\u003csub\u003eHCHO\u003c/sub\u003e of the samples would drop for the competitive adsorption of H\u003csub\u003e2\u003c/sub\u003eO molecules with HCHO molecules\u003csup\u003e51\u003c/sup\u003e. Unexpectedly, as shown in Fig.12 (H\u003csub\u003e2\u003c/sub\u003eO), the introduction of 3% H\u003csub\u003e2\u003c/sub\u003eO not only presented no negative influence on R\u003csub\u003eHCHO\u003c/sub\u003e, on the contrary, the R\u003csub\u003eHCHO\u003c/sub\u003e of aforementioned samples displayed a tiny rise with the increase of H\u003csub\u003e2\u003c/sub\u003eO influx (8%H\u003csub\u003e2\u003c/sub\u003eO). Combined with XPS analysis, the abnormality might be connected to the reaction of adsorbed water with surface active oxygen to generate active hydroxyl groups, thereby supplementing the consumed O\u003csub\u003e\u0026beta;\u003c/sub\u003e\u003csup\u003e59\u003c/sup\u003e. Moreover, H\u003csub\u003e2\u003c/sub\u003eO presented the gainful role in promoting the conversion of formic acid intermediates, so it then accelerated the elimination of HCHO\u003csup\u003e79\u003c/sup\u003e. Interestingly, the adsorption of water vapor did tend to encumber pores and active centers\u003csup\u003e79\u003c/sup\u003e. Synthesizing the above feasible mechanisms, we inferred that the promotional effect of H\u003csub\u003e2\u003c/sub\u003eO molecule on the catalytic activity was slightly higher than its inhibitory effect, and the carrier\u0026rsquo; hierarchical porous structure might greatly enhance the hydrophobicity, which further avoided the disadvantage of water clogging and enhanced its H\u003csub\u003e2\u003c/sub\u003eO tolerance.\u003c/p\u003e\n\u003cp\u003eIn addition, the inhibitory effect of SO\u003csub\u003e2\u003c/sub\u003e was alleviated by means of the promoting function of water vapor to some extent. As shown in Fig.12 (SO\u003csub\u003e2\u003c/sub\u003e+H\u003csub\u003e2\u003c/sub\u003eO), compared with SFG+300ppm SO\u003csub\u003e2\u003c/sub\u003e, a small rise of R\u003csub\u003eHCHO\u003c/sub\u003e of the sample was caught after \u003ca href=\"javascript%3A;\"\u003esequentially\u003c/a\u003eadding 3% H\u003csub\u003e2\u003c/sub\u003eO, which was in line with the above promoting effect of water vapor. Curiously, 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC revealed a higher R\u003csub\u003eHCHO\u003c/sub\u003e after injecting higher concentration water vapor (8%H\u003csub\u003e2\u003c/sub\u003eO) into SFG+800ppmSO\u003csub\u003e2\u003c/sub\u003e, even exceeding that under SFG+300ppmSO\u003csub\u003e2\u003c/sub\u003e+3%H\u003csub\u003e2\u003c/sub\u003eO, revealing that the SO\u003csub\u003e2\u003c/sub\u003e toxicity of the sample was mitigated under higher humidity, which might be owing to the fact that higher concentration of H\u003csub\u003e2\u003c/sub\u003eO sped up the routing of converting adsorbed SO\u003csub\u003e2\u003c/sub\u003e into sulfuric acid, and the mighty internal transport capacity of the hierarchical porous structure further scissored the retention of sulfuric acid in the pores\u003csup\u003e79,80\u003c/sup\u003e. Therefore, 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC might exhibit excellent resistance to SO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO under general industrial flue gas conditions.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.3. Stability and selectivity test\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe stability and selectivity test results of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC catalyst for HCHO abatement were assembled in Fig.13. Under SFG conditions, the stability test of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC sustained for 30 hours. In the first 6 hours, R\u003csub\u003eHCHO\u003c/sub\u003e decreased from 99.2% to 96.8%, and then remained at around 93.7%. The R\u003csub\u003eHCHO\u003c/sub\u003e declined after the accession of 300 ppm SO\u003csub\u003e2\u003c/sub\u003e to SFG, but the addition of 8%H\u003csub\u003e2\u003c/sub\u003eO slashed this negative trend and even exhibited higher R\u003csub\u003eHCHO\u0026nbsp;\u003c/sub\u003ethan that under SFG, which was consonant with the aforesaid performance test analyses. S\u003csub\u003ecd\u003c/sub\u003e also exhibited an identical trend, albeit slightly stronger than R\u003csub\u003eHCHO\u003c/sub\u003e, and it suffered from the compositive impact of 8%H\u003csub\u003e2\u003c/sub\u003eO and 300 ppm SO\u003csub\u003e2\u003c/sub\u003e,which affected R\u003csub\u003eHCHO\u003c/sub\u003e. Some intermediates such as DOM and formate were produced during the abatement of HCHO, which were in line with the subsequent results of in situ DRIFTS. Eventually, R\u003csub\u003eHCHO\u003c/sub\u003e and S\u003csub\u003ecd\u0026nbsp;\u003c/sub\u003eof 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC remained at about 93.5% and 93.7% under 300 ppm SO\u003csub\u003e2\u003c/sub\u003e, demonstrating that it behaved distinguished stability and selectivity.\u003c/p\u003e\n\u003cp\u003e[Fig.13]\u003c/p\u003e"},{"header":"4. Intermediates and mechanism","content":"\u003cp\u003eThe in situ DRIFTS tests were conducted to illustrate the reaction pathways and intermediates of HCHO abatement on 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC. As displayed in Fig.14, after feeding 200 ppm HCHO+6%O\u003csub\u003e2\u003c/sub\u003e/N\u003csub\u003e2\u003c/sub\u003e for only 10 minutes, a peak pertained to the adsorption of HCHO molecules was disclosed at 1135 cm\u003csup\u003e-1\u003c/sup\u003e, which manifested that HCHO was firstly adsorbed on the sample surface\u003csup\u003e81\u003c/sup\u003e. Its intensity progressively attenuated after 10\u0026nbsp;minutes,\u0026nbsp;illustrating that the hierarchical porous structure of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC possibly accelerated the adsorption and subsequent oxidation of HCHO\u003csup\u003e19\u003c/sup\u003e. The bands situated in 2943, 1061, and 809 cm\u003csup\u003e-1\u003c/sup\u003e respectively belonged to v\u003csub\u003es\u003c/sub\u003e(CH\u003csub\u003e2\u003c/sub\u003e), \u0026omega;(CH\u003csub\u003e2\u003c/sub\u003e), and v(C-O) of dioxymethylene (DOM)\u003csup\u003e59\u003c/sup\u003e,\u0026nbsp;implying that the adsorbed HCHO was oxidized into DOM in virtue of its carbonyl electrophilic carbon being attacked by surface nucleophilic surface oxygen\u0026nbsp;[80]. The formation and consumption of DOM attained a dynamic equilibrium after 40 min. Meanwhile, several bands occurred in 1463 and 1387 cm\u003csup\u003e-1\u003c/sup\u003e were associated with \u0026nu;\u003csub\u003eas\u003c/sub\u003e(COO) and \u0026nu;\u003csub\u003es\u003c/sub\u003e(COO) modes of formate species, respectively\u003csup\u003e53,55\u003c/sup\u003e.\u0026nbsp;Moreover, the formate species were generally adsorbed on the catalyst surface in three configurations: bridging, monodentate and bidentate (chelated) frameworks, which could be discriminated via the frequency interval between \u0026nu;\u003csub\u003eas\u003c/sub\u003e(COO) and \u0026nu;\u003csub\u003es\u003c/sub\u003e(COO)\u003csup\u003e44\u003c/sup\u003e.\u0026nbsp;Nevertheless, the intensity of the spectral stretching vibration connected to formate species sustained stable between 10 and 40 min, reflecting that the emergence and consumption of formate species demonstrated a balance, and its diminished intensity after 40 min revealed that the emergence of DOM was constrained, which might correspond to SO\u003csub\u003e2\u003c/sub\u003e poisoning of active metals\u003csup\u003e37,66\u003c/sup\u003e. Furthermore, the characteristic peaks of\u0026nbsp;adsorbed CO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO (bands at 3484 and 2334 cm\u003csup\u003e-1\u003c/sup\u003e) might generate during the oxidation processes of formate species\u003csup\u003e70\u003c/sup\u003e. The uplifted intensities of corresponding CO\u003csub\u003e2\u003c/sub\u003e peak were clearly observed after being exposed to 200 ppm HCHO + 6% O\u003csub\u003e2\u003c/sub\u003e/N\u003csub\u003e2\u003c/sub\u003e for only 10minutes, which was possibly owing to the quick oxidation of HCHO at the reaction begins.\u0026nbsp;The surface hydroxyl groups (-OH) that consumed in the oxidation reactions corresponding to the negative bands located at 3690 cm\u003csup\u003e-1\u003c/sup\u003e, which would be steadily restocked owing to active oxygen activating adsorbed H\u003csub\u003e2\u003c/sub\u003eO molecules\u003csup\u003e6\u003c/sup\u003e. Furthermore, all of the above-mentioned peak intensities reduced marginally between 40 and 50 minutes, while then recovered slightly after 50 minutes. This appearance might be in virtue of the production of metal sulfates mulching the active sites and partial apertures, causing the diminished adsorption and catalytic oxidation of HCHO, and the addition of H\u003csub\u003e2\u003c/sub\u003eO could relieve SO\u003csub\u003e2\u003c/sub\u003e poisoning.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp;[Fig.14]\u003c/p\u003e\n\u003cp\u003eIn the light of above-mentioned analyses,\u0026nbsp;both adsorption and catalytic oxidation worked together for HCHO decontamination over 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC, and the hierarchical\u0026nbsp;porous structure of the carrier accelerated the process. With the comprehension of in-situ DRIFTS, it is proposed that HCHO\u0026nbsp;oxidation obeyed Mars-van-Krevelen mechanism\u003csup\u003e54,70\u003c/sup\u003e. The detailed reaction procedures were presented in Fig.15. Firstly,\u0026nbsp;HCHO was captured by superficial hydroxyl groups and other active sites on the surface of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC.\u0026nbsp;Then, adsorbed HCHO would react with surface active oxygen comprising chemisorbed oxygen and lattice oxygen (marked as O\u003csub\u003es\u003c/sub\u003e), in which the nucleophilic O\u003csub\u003es\u003c/sub\u003e crashed C-H of adsorbed HCHO reforming carbonyl groups into DOM, and DOM was rapidly oxidized into formate species. Meanwhile, formate intermediates after the loss of a hydrogen bond were further oxidized by active hydroxyl groups into unstable H\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e and whereafter it decomposed into CO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO (Eqs. (3)-(11)). Furthermore, the lost hydrogen bond would integrate with the unbonded -OH adsorbed on the catalyst surface, composing H\u003csub\u003e2\u003c/sub\u003eO (Eqs. (12))\u003csup\u003e19,51\u003c/sup\u003e.\u0026nbsp;On the whole, the specific reaction pathways were speculated as follows:\u003c/p\u003e\n\u003cp\u003eHCHO\u003csub\u003e(g)\u003c/sub\u003e+WSAC\u003csub\u003e(surface)\u003c/sub\u003e\u0026rarr;HCHO\u003csub\u003e(ad) \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/sub\u003e(3)\u003c/p\u003e\n\u003cp\u003eO\u003csub\u003e2(g)\u003c/sub\u003e+WSAC\u003csub\u003e(surface)\u003c/sub\u003e\u0026rarr;O\u003csub\u003e2(ad) \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/sub\u003e(4)\u003c/p\u003e\n\u003cp\u003e2CrO\u003csub\u003e3\u003c/sub\u003e\u0026rarr;Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e+3O\u003csub\u003es \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/sub\u003e(5)\u003c/p\u003e\n\u003cp\u003e6CeO\u003csub\u003e2\u003c/sub\u003e+Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026rarr;3Ce\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e+2CrO\u003csub\u003e3 \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/sub\u003e(6)\u003c/p\u003e\n\u003cp\u003e2CeO\u003csub\u003e2\u003c/sub\u003e\u0026rarr;Ce\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e+O\u003csub\u003es \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/sub\u003e(7)\u003c/p\u003e\n\u003cp\u003eCe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e+O\u003csub\u003e(ad)\u003c/sub\u003e\u0026rarr;2CeO\u003csub\u003e2 \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/sub\u003e(8)\u003c/p\u003e\n\u003cp\u003eHCHO\u003csub\u003e(ad)\u003c/sub\u003e+2CrO\u003csub\u003e3\u003c/sub\u003e\u0026rarr;CHO+Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e+H\u003csup\u003e+\u003c/sup\u003e+3O\u003csub\u003es\u003c/sub\u003e\u003csup\u003e- \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/sup\u003e(9)\u003c/p\u003e\n\u003cp\u003eO\u003csub\u003es\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e+CHO\u0026rarr;HCOO\u003csup\u003e- \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/sup\u003e(10)\u003c/p\u003e\n\u003cp\u003eHCOO\u003csup\u003e-\u003c/sup\u003e+OH\u0026rarr;CO\u003csub\u003e2\u003c/sub\u003e+H\u003csub\u003e2\u003c/sub\u003eO \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;(11)\u003c/p\u003e\n\u003cp\u003eH\u003csup\u003e+\u003c/sup\u003e+OH\u0026rarr;H\u003csub\u003e2\u003c/sub\u003eO \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;(12)\u003c/p\u003e\n\u003cp\u003e[Fig.15]\u003c/p\u003e"},{"header":"5. Conclusions","content":"\u003cp\u003eA series of CrO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003ex\u003c/sub\u003e facilitated hierarchical porous biochars derived from walnut husks and rice straws were readily synthesized to investigate for HCHO abatement. The physicochemical properties and abatement mechanism of above-mentioned samples were evaluated by means of BET, XRD, SEM, EDX, H\u003csub\u003e2\u003c/sub\u003e-TPR, XPS, TG-DTG and in situ DRIFTS. The textural parameters including BET surface area, micropore surface area and micropore volume of 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC seemed neutralized by 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WAC and 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/SAC. 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC exhibited superior R\u003csub\u003eHCHO\u003c/sub\u003e, favorable thermal stability and excellent resistance to SO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO in a wide temperature window from 160 to 400℃ partly due to hierarchical porous structure with appropriate ratio of micro-meso-macropores. The boosting effect of H\u003csub\u003e2\u003c/sub\u003eO could alleviate the inhibitory effect of SO\u003csub\u003e2\u003c/sub\u003e. Cr and Ce co-modified WSAC exhibited better performance than that of Cr or Ce individually modified WSAC, which was attributed to the redox cycle of Cr\u003csup\u003e6+\u003c/sup\u003e+Ce\u003csup\u003e3+\u003c/sup\u003e\u0026harr;Cr\u003csup\u003e3+\u003c/sup\u003e+Ce\u003csup\u003e4+\u003c/sup\u003e and the synergistic effect between CrO\u003csub\u003ex\u003c/sub\u003e and CeO\u003csub\u003ex\u003c/sub\u003e, resulting in more active oxygen mobility, higher redox ability and better dispersion of metal oxides. Besides, the hierarchical porous structure of support not only furnished abundant surface functional groups, but also facilitated the accessibility of adsorption/catalytic active sites and boosted the convenient mass transfer of reactants and products. Therefore, these superior properties contributed to boosting the catalytic performance, enhancing the thermal stability and perfecting the resistance to SO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO. Moreover, both adsorption and catalytic oxidation worked together for HCHO elimination over 18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC. Meanwhile, catalytic oxidation predominated gently with the augmentation of reaction time.\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was financially supported by the Natural Science Foundation of Hunan Province (2024JJ5335),\u0026nbsp;the Scientific Research Project of Hunan Provincial Department of Education (22B0458),\u0026nbsp;the National Natural Science Foundation of China (52270102).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analysed during the current study are provided in the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKim, W.-K., Vikrant, K., Younis, S.A., Kim, K.-H., Heynderickx, P.M. Metal oxide/activated carbon composites for the reactive adsorption and catalytic oxidation of formaldehyde and toluene in air. \u003cem\u003eJ. Cleaner. Prod.\u003c/em\u003e \u003cstrong\u003e387,\u003c/strong\u003e 135925 (2023). https://doi.org/10.1016/j.jclepro.2023.135925.\u003c/li\u003e\n\u003cli\u003eChen, S. et al. Unravelling the critical role of silanol in Pt/SiO\u003csub\u003e2\u003c/sub\u003e for room temperature HCHO oxidation: an experimental and DFT study. \u003cem\u003eAppl. Catal. B.\u003c/em\u003e \u003cstrong\u003e331,\u003c/strong\u003e 122672 (2023). https://doi.org/10.1016/j.apcatb.2023.122672.\u003c/li\u003e\n\u003cli\u003eCruz, M.D., Svenningsen, N.B., Nybroe, O., M\u0026uuml;ller, R., Christensen, J.H. Removal of a complex VOC mixture by potted plants-effects on soil microorganisms. \u003cem\u003eEnviron. Sci. Pollut. Res.\u003c/em\u003e \u003cstrong\u003e30, \u003c/strong\u003e55372-55381 (2023). https://10.1007/s11356-023-26137-8.\u003c/li\u003e\n\u003cli\u003eDiao, W., Xu, J., Rao, X., Zhang, Y. Facile Synthesis of Fluorine Doped Rutile TiO\u003csub\u003e2\u003c/sub\u003e Nanorod Arrays for Photocatalytic Removal of Formaldehyde. \u003cem\u003eCatal. Lett.\u003c/em\u003e \u003cstrong\u003e152,\u003c/strong\u003e 1029-1039 (2022). https://10.1007/s10562-021-03700-x.\u003c/li\u003e\n\u003cli\u003eGonz\u0026aacute;lez-Mart\u0026iacute;n, J., Cantera, S., Lebrero, R., Mu\u0026ntilde;oz, R. Biofiltration based on bioactive coatings for the abatement of indoor air VOCs. \u003cem\u003eSustainable Chem. Pharm.\u003c/em\u003e \u003cstrong\u003e31,\u003c/strong\u003e 100960 (2023). https://10.1016/j.scp.2022.100960.\u003c/li\u003e\n\u003cli\u003eLi, J. et al. Construction of Pt-MnO\u003csub\u003e2\u003c/sub\u003e interface with strong electron coupling effect for plasma catalytic oxidation of aromatic VOCs. \u003cem\u003eColloids. Surf. A. \u003c/em\u003e\u003cstrong\u003e665,\u003c/strong\u003e 131248 (2023). https://10.1016/j.colsurfa.2023.131248.\u003c/li\u003e\n\u003cli\u003eWang, J., Shi, Y., Kong, F., Zhou, R. Low-temperature VOCs oxidation performance of Pt/zeolites catalysts with hierarchical pore structure. \u003cem\u003eJ. Environ. Sci.\u003c/em\u003e \u003cstrong\u003e124,\u003c/strong\u003e 505-512 (2023). https://10.1016/j.jes.2021.11.016.\u003c/li\u003e\n\u003cli\u003eZheng, Y. et al. Revealing Opposite Behaviors of Catalyst for VOCs Oxidation: Modulating Electronic Structure of Pt Nanoparticles by Mn Doping. \u003cem\u003eChem. Eng. J.\u003c/em\u003e \u003cstrong\u003e465,\u003c/strong\u003e 142807 (2023). https://doi.org/10.1016/j.cej.2023.142807.\u003c/li\u003e\n\u003cli\u003eYu, Q. et al. Layered double hydroxides-based materials as novel catalysts for gaseous VOCs abatement: Recent advances and mechanisms. \u003cem\u003eCoord. Chem. Rev.\u003c/em\u003e \u003cstrong\u003e471,\u003c/strong\u003e 214738 (2022). https://10.1016/j.ccr.2022.214738.\u003c/li\u003e\n\u003cli\u003eXia, T. et al. Nano-Au supported on CeO\u003csub\u003e2\u003c/sub\u003e for plasma catalytic degradation of n-undecane: Enhancement of activity and stability. \u003cem\u003eSep. Purif. Technol.\u003c/em\u003e \u003cstrong\u003e314,\u003c/strong\u003e 123497 (2023). https://doi.org/10.1016/j.seppur.2023.123497.\u003c/li\u003e\n\u003cli\u003eSeo, B. et al. Computational screening-based development in VOC removal catalyst: Methyl ethyl ketone oxidation over Pt/TiO\u003csub\u003e2\u003c/sub\u003e.\u003cem\u003e Chem. Eng. J.\u003c/em\u003e \u003cstrong\u003e452\u003c/strong\u003e (4)\u003cstrong\u003e,\u003c/strong\u003e 139466 (2023). https://10.1016/j.cej.2022.139466.\u003c/li\u003e\n\u003cli\u003eLi, J. et al. Boosting the plasma catalytic performance of CeO\u003csub\u003e2\u003c/sub\u003e/\u0026gamma;-Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e in long-chain alkane VOCs via tuning the crystallite size. \u003cem\u003eAppl. Surf. Sci.\u003c/em\u003e \u003cstrong\u003e611,\u003c/strong\u003e 155742 (2023). https://10.1016/j.apsusc.2022.155742.\u003c/li\u003e\n\u003cli\u003eChen, Y. et al. CoO\u003csub\u003ex\u003c/sub\u003e supported on rice-husk derived SiO\u003csub\u003e2\u003c/sub\u003e for styrene combustion: The balance of low temperature activity and thermal stability. \u003cem\u003eAppl. Surf. Sci.\u003c/em\u003e \u003cstrong\u003e606,\u003c/strong\u003e 154851 (2022). https://10.1016/j.apsusc.2022.154851.\u003c/li\u003e\n\u003cli\u003eShi, Y., Wan, J., Kong, F., Wang, Y., Zhou, R. Influence of Pt dispersibility and chemical states on catalytic performance of Pt/CeO\u003csub\u003e2\u003c/sub\u003e-TiO\u003csub\u003e2\u003c/sub\u003e catalysts for VOCs low-temperature removal. \u003cem\u003eColloids Surf., A.\u003c/em\u003e \u003cstrong\u003e652,\u003c/strong\u003e 129932 (2022). https://10.1016/j.colsurfa.2022.129932.\u003c/li\u003e\n\u003cli\u003eLu, S., Li, K., Huang, F., Chen, C., Sun, B. Efficient MnO\u003csub\u003ex\u003c/sub\u003e-Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e-CeO\u003csub\u003e2\u003c/sub\u003e catalysts for formaldehyde elimination. \u003cem\u003eAppl. Surf. Sci.\u003c/em\u003e \u003cstrong\u003e400,\u003c/strong\u003e 277-282 (2017). https://10.1016/j.apsusc.2016.12.207.\u003c/li\u003e\n\u003cli\u003eWang, Y., Wang, F., Han, F., Shi, W., Yu, H. Ultra-small CeO\u003csub\u003e2\u003c/sub\u003e nanoparticles supported on SiO\u003csub\u003e2\u003c/sub\u003e for indoor formaldehyde oxidation at low temperature. \u003cem\u003eCatal. Sci. Technol.\u003c/em\u003e \u003cstrong\u003e10,\u003c/strong\u003e 6701-6712 (2020). https://doi.org/10.1039/D0CY00988A.\u003c/li\u003e\n\u003cli\u003eCai, T. et al. Great activity enhancement of Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/\u0026gamma;-Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst for propane combustion by structural modulation. \u003cem\u003eChem. Eng. J.\u003c/em\u003e \u003cstrong\u003e395,\u003c/strong\u003e 125071 (2020). https://10.1016/j.cej.2020.125071.\u003c/li\u003e\n\u003cli\u003eShen, Y. Biomass-derived porous carbons for sorption of Volatile organic compounds (VOCs). \u003cem\u003eFuel.\u003c/em\u003e \u003cstrong\u003e336,\u003c/strong\u003e 126801 (2023). https://10.1016/j.fuel.2022.126801.\u003c/li\u003e\n\u003cli\u003eGao, L. et al. Excellent performance and outstanding resistance to SO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO for formaldehyde abatement over CoMn oxides boosted dual-precursor hierarchical porous biochars derived from liquidambar and orange peel. \u003cem\u003eFuel.\u003c/em\u003e \u003cstrong\u003e317,\u003c/strong\u003e 123539 (2022). https://10.1016/j.fuel.2022.123539.\u003c/li\u003e\n\u003cli\u003eYang, C. et al. Abatement of various types of VOCs by adsorption/catalytic oxidation: A review. \u003cem\u003eChem. Eng. J.\u003c/em\u003e \u003cstrong\u003e370,\u003c/strong\u003e 1128-1153 (2019). https://10.1016/j.cej.2019.03.232.\u003c/li\u003e\n\u003cli\u003eYao, F. et al. Characterization of physicochemical properties of activated carbons prepared from penicillin mycelial residues and its adsorption properties for VOCs.\u003cem\u003e J. Environ. Chem. Eng. \u003c/em\u003e\u003cstrong\u003e11\u003c/strong\u003e (3)\u003cstrong\u003e,\u003c/strong\u003e 109733 (2023). https://10.1016/j.jece.2023.109733.\u003c/li\u003e\n\u003cli\u003eLiu, X. et al. Carbon materials with hierarchical porosity: Effect of template removal strategy and study on their electrochemical properties.\u003cem\u003e Carbon.\u003c/em\u003e \u003cstrong\u003e130,\u003c/strong\u003e 680-691 (2018). https://doi.org/10.1016/j.carbon.2018.01.046.\u003c/li\u003e\n\u003cli\u003eAn, B. et al. Cooperative copper centres in a metal-organic framework for selective conversion of CO\u003csub\u003e2\u003c/sub\u003e to ethanol. \u003cem\u003eNat. Catal\u003c/em\u003e. \u003cstrong\u003e2,\u003c/strong\u003e 709-717 (2019). https://doi:10.1038/s41929-019-0308-5.\u003c/li\u003e\n\u003cli\u003eQu, Z. et al. A new insight into SO\u003csub\u003e2\u003c/sub\u003e low-temperature catalytic oxidation in porous carbon materials: nondissociated O\u003csub\u003e2\u003c/sub\u003e molecule as oxidant. \u003cem\u003eCatal. Sci. Technol.\u003c/em\u003e \u003cstrong\u003e9,\u003c/strong\u003e 4327-4338 (2019). https://10.1039/C9CY00960D.\u003c/li\u003e\n\u003cli\u003eJin, X. et al. Catalytic conversion of toluene by biochar modified with KMnO\u003csub\u003e4\u003c/sub\u003e. \u003cem\u003eFuel.\u003c/em\u003e \u003cstrong\u003e332\u003c/strong\u003e (2)\u003cstrong\u003e,\u003c/strong\u003e 126237 (2023). https://10.1016/j.fuel.2022.126237.\u003c/li\u003e\n\u003cli\u003eCheng, S. et al. Efficient removal of heavy metals from aqueous solutions by Mg/Fe bimetallic oxide-modified biochar in monometallic and bimetallic systems: Experiments and DFT investigations. \u003cem\u003eJ. Cleaner. Prod.\u003c/em\u003e \u003cstrong\u003e403,\u003c/strong\u003e 136821 (2023). https://doi.org/10.1016/j.jclepro.2023.136821.\u003c/li\u003e\n\u003cli\u003eTu, S. et al. Complete catalytic oxidation of formaldehyde at room temperature on Mn\u003csub\u003ex\u003c/sub\u003eCo\u003csub\u003e3-x\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e catalysts derived from metal-organic frameworks. \u003cem\u003eAppl. Catal. A.\u003c/em\u003e \u003cstrong\u003e611,\u003c/strong\u003e 117975 (2021). https://10.1016/j.apcata.2020.117975.\u003c/li\u003e\n\u003cli\u003eZeng, Y. et al. CoMn\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e supported on carbon nanotubes for effective low-temperature HCHO removal. \u003cem\u003eJ. Alloy. Compd. \u003c/em\u003e\u003cstrong\u003e859,\u003c/strong\u003e 157808 (2021). https://10.1016/j.jallcom.2020.157808.\u003c/li\u003e\n\u003cli\u003eZhu, Y. et al. Regulating CeO\u003csub\u003e2\u003c/sub\u003e morphologies on the catalytic oxidation of toluene at lower temperature: A study of the structure-activity relationship. \u003cem\u003eJ. Catal.\u003c/em\u003e \u003cstrong\u003e418,\u003c/strong\u003e 151-162 (2023). https://doi.org/10.1016/j.jcat.2023.01.012.\u003c/li\u003e\n\u003cli\u003eLi, Z. et al. CeO\u003csub\u003e2\u003c/sub\u003e from pyrolysis of MOFs for efficient catalytic combustion of VOCs. \u003cem\u003eMol. Catal.\u003c/em\u003e \u003cstrong\u003e535,\u003c/strong\u003e 112857 (2023). https://10.1016/j.mcat.2022.112857.\u003c/li\u003e\n\u003cli\u003eLi, L. et al. Effects of different methods of introducing Mo on denitration performance and anti-SO\u003csub\u003e2\u003c/sub\u003e poisoning performance of CeO\u003csub\u003e2\u003c/sub\u003e. \u003cem\u003eChin. J. Catal.\u003c/em\u003e \u003cstrong\u003e42\u003c/strong\u003e (9)\u003cstrong\u003e,\u003c/strong\u003e 1488-1499 (2021a). https://10.1016/S1872-2067(20)63778-0.\u003c/li\u003e\n\u003cli\u003eZhu, L. et al. NH\u003csub\u003e3\u003c/sub\u003e-SCR performance and SO\u003csub\u003e2\u003c/sub\u003e resistance comparison of CeO\u003csub\u003e2\u003c/sub\u003e based catalysts with Fe/Mo additive surface decoration. \u003cem\u003eChem. Eng. J.\u003c/em\u003e \u003cstrong\u003e428\u003c/strong\u003e (15)\u003cstrong\u003e,\u003c/strong\u003e 131372 (2022). https://10.1016/j.cej.2021.131372.\u003c/li\u003e\n\u003cli\u003eZhang, N. et al. Synchronously constructing the optimal redox-acidity of sulfate and RuO\u003csub\u003ex\u003c/sub\u003e Co-modified CeO\u003csub\u003e2\u003c/sub\u003e for catalytic combustion of chlorinated VOCs. \u003cem\u003eChem. Eng. J.\u003c/em\u003e \u003cstrong\u003e454,\u003c/strong\u003e 140391 (2023). https://10.1016/j.cej.2022.140391.\u003c/li\u003e\n\u003cli\u003eXiao, M. et al. Ni-doping-induced oxygen vacancy in Pt-CeO\u003csub\u003e2\u003c/sub\u003e catalyst for toluene oxidation: Enhanced catalytic activity, water-resistance, and SO\u003csub\u003e2\u003c/sub\u003e-tolerance. \u003cem\u003eAppl. Catal. B.\u003c/em\u003e \u003cstrong\u003e323,\u003c/strong\u003e 122173 (2023). https://10.1016/j.apcatb.2022.122173.\u003c/li\u003e\n\u003cli\u003eYu, S. et al. Synthesis of CrO\u003csub\u003ex\u003c/sub\u003e/C catalysts for low temperature NH\u003csub\u003e3\u003c/sub\u003e-SCR with enhanced regeneration ability in the presence of SO\u003csub\u003e2\u003c/sub\u003e. \u003cem\u003eRSC. Adv.\u003c/em\u003e \u003cstrong\u003e8\u003c/strong\u003e (7)\u003cstrong\u003e,\u003c/strong\u003e 3858-3868 (2018). https://10.1039/c7ra09680a.\u003c/li\u003e\n\u003cli\u003eJia, Y. et al. Investigation of the Effect of SO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO on VPO-Cr-PEG/TiO\u003csub\u003e2\u003c/sub\u003e for the Low-Temperature SCR de-NO\u003csub\u003ex\u003c/sub\u003e. \u003cem\u003eFront. Mater. \u003c/em\u003e\u003cstrong\u003e6,\u003c/strong\u003e 320 (2019). https://10.3389/fmats.2019.00320.\u003c/li\u003e\n\u003cli\u003eLiu, W. et al. Promotion Effect of Chromium on the Activity and SO\u003csub\u003e2\u003c/sub\u003e Resistance of CeO\u003csub\u003e2\u003c/sub\u003e-TiO\u003csub\u003e2\u003c/sub\u003e Catalysts for the NH\u003csub\u003e3\u003c/sub\u003e-SCR Reaction. \u003cem\u003eInd. Eng. Chem. Res.\u003c/em\u003e \u003cstrong\u003e60\u003c/strong\u003e (31)\u003cstrong\u003e,\u003c/strong\u003e 11676-11688 (2021). https://10.1021/acs.iecr.1c00898.\u003c/li\u003e\n\u003cli\u003eZhang, D. et al. Cr Doping MnO\u003csub\u003ex\u003c/sub\u003e Adsorbent Significantly Improving Hg\u003csup\u003e0\u003c/sup\u003e Removal and SO\u003csub\u003e2\u003c/sub\u003e Resistance from Coal-Fired Flue Gas and the Mechanism Investigation. \u003cem\u003eInd. Eng. Chem. Res.\u003c/em\u003e \u003cstrong\u003e57\u003c/strong\u003e (50)\u003cstrong\u003e,\u003c/strong\u003e 17245-17258 (2018). https://10.1021/acs.iecr.8b04857.\u003c/li\u003e\n\u003cli\u003eYang, P., Zuo, SF., Shi, Z.N., Tao, F., Zhou, R.X. Elimination of 1,2-dichloroethane over (Ce,Cr)\u003csub\u003ex\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e/MO\u003csub\u003ey\u003c/sub\u003e catalysts (M = Ti, V, Nb, Mo, W and La). \u003cem\u003eAppl. Catal.\u003c/em\u003e \u003cstrong\u003e191,\u003c/strong\u003e 53-61 (2016). https://doi.org/10.1016/j.apcatb.2016.03.017.\u003c/li\u003e\n\u003cli\u003eXia, C. et al. Recent Advances on Electrospun Nanomaterials for Zinc-Air Batteries. \u003cem\u003eSmall. Sci.\u003c/em\u003e \u003cstrong\u003e1,\u003c/strong\u003e 1-16 (2021). https://10.1002/smsc.202100010.\u003c/li\u003e\n\u003cli\u003eQin, J. et al. Self-activation of potassium/iron citrate-assisted production of porous carbon/porous biochar composites from macroalgae for high-performance sorption of sulfamethoxazole. \u003cem\u003eBioresour. Technol.\u003c/em\u003e \u003cstrong\u003e369,\u003c/strong\u003e 128361 (2023). https://10.1016/j.biortech.2022.128361.\u003c/li\u003e\n\u003cli\u003eYe, G. et al. Preparing hierarchical porous carbon with well-developed microporosity using alkali metal-catalyzed hydrothermal carbonization for VOCs adsorption. \u003cem\u003eChemosphere.\u003c/em\u003e \u003cstrong\u003e298,\u003c/strong\u003e 134248 (2022). https://10.1016/j.chemosphere.2022.134248.\u003c/li\u003e\n\u003cli\u003eZhu, L., Shen, D., Luo, K.H. A critical review on VOCs adsorption by different porous materials: Species, mechanisms and modification methods. \u003cem\u003eJ. Hazard. Mater.\u003c/em\u003e \u003cstrong\u003e389,\u003c/strong\u003e 122102 (2020). https://10.1016/j.jhazmat.2020.122102.\u003c/li\u003e\n\u003cli\u003eGao, L. et al. Superior performance and resistance to SO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO over CoO\u003csub\u003ex\u003c/sub\u003e-modifed MnO\u003csub\u003ex\u003c/sub\u003e/biomass activated carbons for simultaneous Hg\u003csup\u003e0\u003c/sup\u003e and NO removal. \u003cem\u003eChem. Eng. J.\u003c/em\u003e \u003cstrong\u003e371,\u003c/strong\u003e 781-795 (2019). https://10.1016/j.cej.2019.04.104.\u003c/li\u003e\n\u003cli\u003eVenkataswamy, P. et al. Cr-Doped CeO\u003csub\u003e2\u003c/sub\u003e Nanorods for CO Oxidation: Insights into Promotional Effect of Cr on Structure and Catalytic Performance. \u003cem\u003eCatal. Lett.\u003c/em\u003e \u003cstrong\u003e150,\u003c/strong\u003e 948-962 (2020). https://10.1007/s10562-019-03014-z.\u003c/li\u003e\n\u003cli\u003eGao, E. et al. Understanding the co-effects of manganese and cobalt on the enhanced SCR performance for Mn\u003csub\u003ex\u003c/sub\u003eCo\u003csub\u003e1x\u003c/sub\u003eCr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4 \u003c/sub\u003espinel-type catalysts. \u003cem\u003eCatal. Sci. Technol.\u003c/em\u003e \u003cstrong\u003e10,\u003c/strong\u003e 4752-4765 (2020). https://10.1039/D0CY00872A.\u003c/li\u003e\n\u003cli\u003eTachibana, N., Yukawa, Y., Morikawa, K., Kawaguchi, M., Shimanoe, K. Pt nanoparticles supported on nitrogen‑doped porous carbon as efficient oxygen reduction catalysts synthesized via a simple alcohol reduction method. \u003cem\u003eSN. Appl. Sci.\u003c/em\u003e \u003cstrong\u003e3,\u003c/strong\u003e 338 (2021). https://10.1007/s42452-021-04343-8.\u003c/li\u003e\n\u003cli\u003eWang, J., Yang, P., Guo, X., Zhou, R. Investigation on the structure-activity relationship of Nb\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e promoting CeO\u003csub\u003e2\u003c/sub\u003e-CrO\u003csub\u003ex\u003c/sub\u003e-Nb\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e catalysts for 1,2-dichloroethane elimination. \u003cem\u003eMol. Catal.\u003c/em\u003e \u003cstrong\u003e470,\u003c/strong\u003e 75-81 (2019). https://10.1016/j.mcat.2019.03.010.\u003c/li\u003e\n\u003cli\u003eJiang, G. et al. Insight into the Ag-CeO\u003csub\u003e2\u003c/sub\u003e interface and mechanism of catalytic oxidation of formaldehyde. \u003cem\u003eAppl. Surf. Sci.\u003c/em\u003e \u003cstrong\u003e549,\u003c/strong\u003e 149277 (2021). https://10.1016/j.apsusc.2021.149277.\u003c/li\u003e\n\u003cli\u003eGao, L. et al. Simultaneous removal of NO and Hg\u003csup\u003e0\u003c/sup\u003e from simulated fiue gas over CoO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003e2\u003c/sub\u003e loaded biomass activated carbon derived from maize straw at low temperatures. \u003cem\u003eChem. Eng. J. \u003c/em\u003e\u003cstrong\u003e342,\u003c/strong\u003e 339-349 (2018). https://10.1016/j.cej.2018.02.100.\u003c/li\u003e\n\u003cli\u003eDu, X. et al. Promotional removal of HCHO from simulated flue gas over Mn-Fe oxides modified activated coke. \u003cem\u003eAppl. Catal. B.\u003c/em\u003e \u003cstrong\u003e232,\u003c/strong\u003e 37-48 (2018). https://10.1016/j.apcatb.2018.03.034.\u003c/li\u003e\n\u003cli\u003eXu, C., Jin, L., Wang, X., Chen, Y., Dai, L. Honeycomb-like porous Ce-Cr oxide/N-doped carbon nanostructure: Achieving high catalytic performance for the selective oxidation of cyclohexane to KA oil. \u003cem\u003eCarbon.\u003c/em\u003e \u003cstrong\u003e160,\u003c/strong\u003e 287-297 (2020a). https://doi.org/10.1016/j.carbon.2020.01.023.\u003c/li\u003e\n\u003cli\u003eXu, J., Qu, Z., Ke, G., Wang, Y., Huang, B. Catalytic activity of gold-silver nanoalloys for HCHO oxidation: Effect of hydroxyl and particle size. \u003cem\u003eAppl. Surf. Sci.\u003c/em\u003e \u003cstrong\u003e513,\u003c/strong\u003e 145910 (2020b). https://10.1016/j.apsusc.2020.145910.\u003c/li\u003e\n\u003cli\u003eYu, C. et al. A MnO\u003csub\u003ex\u003c/sub\u003e@Eu-CeO\u003csub\u003ex\u003c/sub\u003e nanorod catalyst with multiple protective effects: Strong SO\u003csub\u003e2\u003c/sub\u003e-tolerance for low temperature DeNO\u003csub\u003ex\u003c/sub\u003e processes. \u003cem\u003eJ. Haz. Mat.\u003c/em\u003e \u003cstrong\u003e399,\u003c/strong\u003e 123011 (2020). https://10.1016/j.jhazmat.2020.123011.\u003c/li\u003e\n\u003cli\u003eLi, R. et al. Improved Oxygen Activation over a Carbon/Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e Nanocomposite for Efficient Catalytic Oxidation of Formaldehyde at Room Temperature. \u003cem\u003eEnviron. Sci. Technol.\u003c/em\u003e \u003cstrong\u003e55,\u003c/strong\u003e 4054-4063 (2021c). https://10.1021/acs.est.1c00490.\u003c/li\u003e\n\u003cli\u003eXie, J. et al. Exploring removal of formaldehyde at room temperature over Cr- and Zn-modified Co\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e catalyst prepared by hydrothermal method. \u003cem\u003eRes. Chem. Intermed.\u003c/em\u003e \u003cstrong\u003e46,\u003c/strong\u003e 1789-1804 (2020). https://10.1007/s11164-019-04063-0.\u003c/li\u003e\n\u003cli\u003eFu, Z. et al. Promotional effect of SO\u003csub\u003e2\u003c/sub\u003e on Cr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts for the marine NH\u003csub\u003e3\u003c/sub\u003e-SCR reaction. \u003cem\u003eChem. Eng. J.\u003c/em\u003e \u003cstrong\u003e361,\u003c/strong\u003e 830-838 (2019). https://10.1016/j.cej.2018.12.100.\u003c/li\u003e\n\u003cli\u003eLiu, Z. et al. Catalytic Oxidation of Formaldehyde over Manganese-Based Catalysts and the Influence of Synergistic Effect(Review). \u003cem\u003eProg. Chem.\u003c/em\u003e \u003cstrong\u003e31 \u003c/strong\u003e(2-3)\u003cstrong\u003e,\u003c/strong\u003e 311-321 (2019). https://10.7536/PC180435.\u003c/li\u003e\n\u003cli\u003eDu, X. et al. Highly efficient simultaneous removal of HCHO and elemental mercury over Mn-Co oxides promoted Zr-AC samples. \u003cem\u003eJ. Haz. Mat.\u003c/em\u003e \u003cstrong\u003e408,\u003c/strong\u003e 124830 (2021). https://10.1016/j.jhazmat.2020.124830.\u003c/li\u003e\n\u003cli\u003eLin, X. et al. Evolution of oxygen vacancies in MnO\u003csub\u003ex\u003c/sub\u003e-CeO\u003csub\u003e2\u003c/sub\u003e mixed oxides for soot oxidation. \u003cem\u003eAppl. Catal. B.\u003c/em\u003e \u003cstrong\u003e223,\u003c/strong\u003e 91-102 (2018). https://10.1016/j.apcatb.2017.06.071.\u003c/li\u003e\n\u003cli\u003eLyu, Y. et al. Catalytic oxidation of toluene over MnO\u003csub\u003e2\u003c/sub\u003e catalysts with diferent Mn (II) precursors and the study of reaction pathway. \u003cem\u003eFuel.\u003c/em\u003e \u003cstrong\u003e262,\u003c/strong\u003e 116610 (2020). https://doi.org/10.1016/j.fuel.2019.116610.\u003c/li\u003e\n\u003cli\u003eYi, L. et al. LaO\u003csub\u003ex\u003c/sub\u003e modified MnO\u003csub\u003ex\u003c/sub\u003e loaded biomass activated carbon and its enhanced performance for simultaneous abatement of NO and Hg\u003csup\u003e0\u003c/sup\u003e. \u003cem\u003eEnviron. Sci. Pollut. R.\u003c/em\u003e \u003cstrong\u003e29,\u003c/strong\u003e 2258-2275 (2022). https://10.1007/s11356-021-15752-y.\u003c/li\u003e\n\u003cli\u003eZhang, H. et al. Structure, surface and reactivity of activated carbon: From model soot to Bio Diesel soot. \u003cem\u003eFuel.\u003c/em\u003e \u003cstrong\u003e257, \u003c/strong\u003e116038 (2019). https://10.1016/j.fuel.2019.116038.\u003c/li\u003e\n\u003cli\u003eZhang, D. et al. Efficient removal of formaldehyde by polyethyleneimine modified activated carbon in a fixed bed. \u003cem\u003eEnviron. Sci. Pollut. Res.\u003c/em\u003e \u003cstrong\u003e27\u003c/strong\u003e (15)\u003cstrong\u003e,\u003c/strong\u003e 18109-18116 (2020). https://10.1007/s11356-020-08019-5.\u003c/li\u003e\n\u003cli\u003eLi, Y., Liu, Y., Yang, W., Liu, L., Pan, J. Adsorption of elemental mercury in flue gas using biomass porous carbons modified by microwave/hydrogen peroxide. \u003cem\u003eFuel.\u003c/em\u003e \u003cstrong\u003e291,\u003c/strong\u003e 120152 (2021b). https://10.1016/j.fuel.2021.120152.\u003c/li\u003e\n\u003cli\u003eChen, G. et al. CrO\u003csub\u003ex\u003c/sub\u003e-MnO\u003csub\u003ex\u003c/sub\u003e-TiO\u003csub\u003e2\u003c/sub\u003e adsorbent with high resistance to SO\u003csub\u003e2\u003c/sub\u003e poisoning for Hg\u003csup\u003e0\u003c/sup\u003e removal at low temperature. \u003cem\u003eJ. Ind. Eng. Chem.\u003c/em\u003e \u003cstrong\u003e55,\u003c/strong\u003e 119-127 (2017). https://10.1016/j.jiec.2017.06.035.\u003c/li\u003e\n\u003cli\u003eFeng, X. et al. Yolk-shell-like mesoporous CoCrO\u003csub\u003ex\u003c/sub\u003e with superior activity and chlorine resistance in dichloromethane destruction. \u003cem\u003eAppl. Catal. B.\u003c/em\u003e \u003cstrong\u003e264,\u003c/strong\u003e 118493 (2020). https://10.1016/j.jiec.2017.06.035.\u003c/li\u003e\n\u003cli\u003eWu, J., Xia, Q., Xiao, J., Li, Z. Chromium-based metal-organic framework MIL-101 as a highly effective catalyst in plasma for toluene removal. \u003cem\u003eJ. Phys. D.\u003c/em\u003e \u003cstrong\u003e50,\u003c/strong\u003e 475202 (2017). https://10.1088/1361-6463/aa90f3.\u003c/li\u003e\n\u003cli\u003eFang, X., Liu, Y., Cheng, Y., Cen, Y. Mechanism of Ce-Modified Birnessite-MnO\u003csub\u003e2\u003c/sub\u003e in Promoting SO\u003csub\u003e2\u003c/sub\u003e Poisoning Resistance for Low-Temperature NH\u003csub\u003e3\u003c/sub\u003e-SCR. \u003cem\u003eACS. Catal.\u003c/em\u003e \u003cstrong\u003e11,\u003c/strong\u003e 4125-4135 (2021). https://10.1021/acscatal.0c05697.\u003c/li\u003e\n\u003cli\u003eChen, J. et al. Incorporating Mn cation as anchor to atomically disperse Pt on TiO\u003csub\u003e2\u003c/sub\u003e for lowtemperature removal of formaldehyde. \u003cem\u003eAppl. Catal. B.\u003c/em\u003e \u003cstrong\u003e259,\u003c/strong\u003e 118013 (2019). https://10.1016/j.apcatb.2019.118013.\u003c/li\u003e\n\u003cli\u003eLi, H. et al. Enhanced activity and SO\u003csub\u003e2\u003c/sub\u003e resistance of Co-modified CeO\u003csub\u003e2\u003c/sub\u003e-TiO\u003csub\u003e2\u003c/sub\u003e catalyst prepared by facile co-precipitation for elemental mercury removal in flue gas. \u003cem\u003eAppl. Organomet. Chem.\u003c/em\u003e \u003cstrong\u003e34\u003c/strong\u003e (4)\u003cstrong\u003e,\u003c/strong\u003e e5463 (2020). https://10.1002/aoc.5463.\u003c/li\u003e\n\u003cli\u003eZhang, Z., Yang, B., Ma, H. Aliphatic Amine Decorating Metal-Organic Framework for Durable SO\u003csub\u003e2\u003c/sub\u003e Capture from Flue Gas. \u003cem\u003eSep. Purif. Technol.\u003c/em\u003e \u003cstrong\u003e259,\u003c/strong\u003e 118164 (2021). https://10.1016/j.seppur.2020.118164.\u003c/li\u003e\n\u003cli\u003eTazibet, S., Velasco, L. F., Lodewyckx, P., MHamed, D.A., Boucheffa, Y. Systematic study of the role played by ZnCl\u003csub\u003e2\u003c/sub\u003e during the carbonization of a chemically activated carbon by TG-MS and DSC. \u003cem\u003eJ.\u003c/em\u003e \u003cem\u003eTherm. Anal. Calorim.\u003c/em\u003e \u003cstrong\u003e134\u003c/strong\u003e (3)\u003cstrong\u003e,\u003c/strong\u003e 1395-1404 (2018)\u003cem\u003e. \u003c/em\u003ehttps://10.1007/s10973-018-7246-3.\u003c/li\u003e\n\u003cli\u003eRahbar-Shamskar, K., Rashidi, A., Baniyaghoob, S., Khodabakhshi, S. In-situ catalytic fast pyrolysis of reed as a sustainable method for production of porous carbon as VOCs adsorbents. \u003cem\u003eJ. Anal. Appl. Pyrolysis.\u003c/em\u003e \u003cstrong\u003e164, \u003c/strong\u003e105520 (2022). https://10.1016/j.jaap.2022.105520.\u003c/li\u003e\n\u003cli\u003eZhang, H., Tan, L., Zhang, Z., Zhang, G., Lu, J. Activated carbon and poly-o-anisidine (POA) synergistic supported Pt nanoparticles as a highly efficient catalyst for electrocatalytic oxidation of formaldehyde. \u003cem\u003eElectrochim. Acta.\u003c/em\u003e \u003cstrong\u003e388,\u003c/strong\u003e 138617 (2021). https://10.1016/j.electacta.2021.138617.\u003c/li\u003e\n\u003cli\u003eSaad, M., Szymaszek, A., Biafias, A., Samojeden, B., Motak, M. SO\u003csub\u003e2\u003c/sub\u003e Poisoning and Recovery of Copper-Based Activated Carbon Catalysts for Selective Catalytic Reduction of NO with NH\u003csub\u003e3\u003c/sub\u003e at Low Temperature. \u003cem\u003eCatalysts.\u003c/em\u003e \u003cstrong\u003e10\u003c/strong\u003e (12)\u003cstrong\u003e,\u003c/strong\u003e 1426 (2020). https://10.3390/catal10121426.\u003c/li\u003e\n\u003cli\u003eShao, J. et al. Enhance SO\u003csub\u003e2\u003c/sub\u003e adsorption performance of biochar modified by CO\u003csub\u003e2\u003c/sub\u003e activation and amine impregnation.\u003cem\u003e Fuel.\u003c/em\u003e \u003cstrong\u003e224, \u003c/strong\u003e138-146 (2018). https://10.1016/j.fuel.2018.03.064.\u003c/li\u003e\n\u003cli\u003eYu, J. et al. Insight into the key factors in fast adsorption of organic pollutants by hierarchical porous biochar. \u003cem\u003eJ. Haz. Mat.\u003c/em\u003e \u003cstrong\u003e403,\u003c/strong\u003e 123610 (2021). https://10.1016/j.jhazmat.2020.123610.\u003c/li\u003e\n\u003cli\u003eMa, C. et al. Effects of H\u003csub\u003e2\u003c/sub\u003eO on HCHO and CO oxidation at room-temperature catalyzed by MCo\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (M=Mn, Ce and Cu) materials. \u003cem\u003eAppl. Catal. B.\u003c/em\u003e \u003cstrong\u003e254,\u003c/strong\u003e 76-85 (2019). https://10.1016/j.apcatb.2019.04.085.\u003c/li\u003e\n\u003cli\u003eLi, B., Ma, C. Study on the mechanism of SO\u003csub\u003e2\u003c/sub\u003e removal by activated carbon. \u003cem\u003eEnergy Procedia.\u003c/em\u003e \u003cstrong\u003e153,\u003c/strong\u003e 471-477 (2018). https://10.1016/j.egypro.2018.10.063.\u003c/li\u003e\n\u003cli\u003eXiang, N. et al. Promoting effect and mechanism of alkali Na on Pd/SBA-15 for room temperature formaldehyde catalytic oxidation. \u003cem\u003eChem. Cat. Chem.\u003c/em\u003e \u003cstrong\u003e11,\u003c/strong\u003e 5098-5107 (2019). http://dx.doi.org/10.1002/cctc.201901039.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTable.1.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe BET specific surface area and pore characteristic parameters of\u0026nbsp;primaeval\u0026nbsp;WSAC and modified samples.\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"566\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 21.164%;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 11.8166%;\"\u003e\n \u003cp\u003eBET surface\u003c/p\u003e\n \u003cp\u003earea (m\u003csup\u003e2\u003c/sup\u003e/g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12.6984%;\"\u003e\n \u003cp\u003eMicopore area (m\u003csup\u003e2\u003c/sup\u003e/g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13.0511%;\"\u003e\n \u003cp\u003eMicopore ratio\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 12.8748%;\"\u003e\n \u003cp\u003eTotal pore volume (cm\u003csup\u003e3\u003c/sup\u003e/g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14.9912%;\"\u003e\n \u003cp\u003eMicopore volume\u003c/p\u003e\n \u003cp\u003e(cm\u003csup\u003e3\u003c/sup\u003e/g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13.4039%;\"\u003e\n \u003cp\u003eAverage pore diameter (nm)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 21.164%;\"\u003e\n \u003cp\u003eprimaeval\u0026nbsp;WSAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11.8166%;\"\u003e\n \u003cp\u003e729.667\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.6984%;\"\u003e\n \u003cp\u003e577.145\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.0511%;\"\u003e\n \u003cp\u003e79.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.8748%;\"\u003e\n \u003cp\u003e0.376\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.9912%;\"\u003e\n \u003cp\u003e0.239\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.4039%;\"\u003e\n \u003cp\u003e2.059\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 21.164%;\"\u003e\n \u003cp\u003e6%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11.8166%;\"\u003e\n \u003cp\u003e547.779\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.6984%;\"\u003e\n \u003cp\u003e412.734\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.0511%;\"\u003e\n \u003cp\u003e75.4%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.8748%;\"\u003e\n \u003cp\u003e0.285\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.9912%;\"\u003e\n \u003cp\u003e0.172\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.4039%;\"\u003e\n \u003cp\u003e2.077\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 21.164%;\"\u003e\n \u003cp\u003e12%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11.8166%;\"\u003e\n \u003cp\u003e426.674\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.6984%;\"\u003e\n \u003cp\u003e319.984\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.0511%;\"\u003e\n \u003cp\u003e75.7%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.8748%;\"\u003e\n \u003cp\u003e0.218\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.9912%;\"\u003e\n \u003cp\u003e0.132\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.4039%;\"\u003e\n \u003cp\u003e2.045\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 21.164%;\"\u003e\n \u003cp\u003e18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11.8166%;\"\u003e\n \u003cp\u003e407.439\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.6984%;\"\u003e\n \u003cp\u003e323.039\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.0511%;\"\u003e\n \u003cp\u003e78.5%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.8748%;\"\u003e\n \u003cp\u003e0.211\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.9912%;\"\u003e\n \u003cp\u003e0.133\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.4039%;\"\u003e\n \u003cp\u003e2.068\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 21.164%;\"\u003e\n \u003cp\u003e24%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WSAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11.8166%;\"\u003e\n \u003cp\u003e369.662\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.6984%;\"\u003e\n \u003cp\u003e280.231\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.0511%;\"\u003e\n \u003cp\u003e75.8%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.8748%;\"\u003e\n \u003cp\u003e0.190\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.9912%;\"\u003e\n \u003cp\u003e0.115\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.4039%;\"\u003e\n \u003cp\u003e2.055\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 21.164%;\"\u003e\n \u003cp\u003e18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/WAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11.8166%;\"\u003e\n \u003cp\u003e689.071\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.6984%;\"\u003e\n \u003cp\u003e622.516\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.0511%;\"\u003e\n \u003cp\u003e90.3%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.8748%;\"\u003e\n \u003cp\u003e0.307\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.9912%;\"\u003e\n \u003cp\u003e0.256\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.4039%;\"\u003e\n \u003cp\u003e1.785\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 21.164%;\"\u003e\n \u003cp\u003e18%Cr\u003csub\u003e0.5\u003c/sub\u003eCe\u003csub\u003e0.5\u003c/sub\u003e/SAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11.8166%;\"\u003e\n \u003cp\u003e373.594\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.6984%;\"\u003e\n \u003cp\u003e197.819\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.0511%;\"\u003e\n \u003cp\u003e52.9%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 12.8748%;\"\u003e\n \u003cp\u003e0.225\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.9912%;\"\u003e\n \u003cp\u003e0.086\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13.4039%;\"\u003e\n \u003cp\u003e2.405\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"hierarchical porous biochar, catalytic oxidation, formaldehyde, SO2 resistance","lastPublishedDoi":"10.21203/rs.3.rs-5297317/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5297317/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA suite of CrCe oxides facilitated hierarchical porous biochars from walnut husks and rice straws (XCryCe1-y/WSAC) were readily synthesized for formaldehyde (HCHO) abatement. BET, XRD, XPS, SEM, H2-TPR, TG-DTG, and in situ DRIFTS were adopted to disclose their physicochemical properties and the elimination mechanism of HCHO. 18%Cr0.5Ce0.5/WSAC exhibited splendid HCHO abatement efficiency (99.2%) at 280°C. The effects of O2, SO2, H2O for HCHO abatement over 18%Cr0.5Ce0.5/WSAC were trialed, and the strangulation influences of SO2 counteracted the furtherance effect of O2 to some extent, which was relieved by the facilitation of H2O. CrOx-CeOx co-facilitated WSAC presented better performance than Cr or Ce oxide separately facilitated WSACs, which was associated with the redox cycle of Cr6++Ce3+↔Cr3++Ce4+, resulting in higher redox capability, better dispersion of active ingredient, more oxygen vacancies and superior active oxygen mobility. Furthermore, the hierarchical porous support accelerated the diffusion and mass transfer of reactants and intermediates. Noteworthily, the effects of CrOx-CeOx and the hierarchical porous structure of the support on the tolerance to SO2 and H2O were deeply and systematically investigated. Ultimately, 18%Cr0.5Ce0.5/WSAC emerged desirable prospects in practical applications thanks to splendid catalytic performance and satisfactory resistance to SO2 and H2O.\u003c/p\u003e","manuscriptTitle":"Outstanding formaldehyde abatement performance and preferable resistance to SO 2 and H 2 O over CrO x -CeO x facilitated hierarchical porous biochars catalysts","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-11-19 08:31:59","doi":"10.21203/rs.3.rs-5297317/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"2c8b9570-23b5-4787-92a5-f757fae07c7c","owner":[],"postedDate":"November 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":40048141,"name":"Earth and environmental sciences/Environmental sciences"},{"id":40048142,"name":"Physical sciences/Chemistry"},{"id":40048143,"name":"Physical sciences/Materials science"}],"tags":[],"updatedAt":"2025-01-16T15:53:37+00:00","versionOfRecord":[],"versionCreatedAt":"2024-11-19 08:31:59","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5297317","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5297317","identity":"rs-5297317","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}