Selective catalytic oxidation of methanol on Pt-modified Cu/SSZ-13 zeolites: A strategy to change the catalytic performance by impregnation sequential

Selective catalytic oxidation of methanol on Pt-modified Cu/SSZ-13 zeolites: A strategy to change the catalytic performance by impregnation sequential | 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 Research Article Selective catalytic oxidation of methanol on Pt-modified Cu/SSZ-13 zeolites: A strategy to change the catalytic performance by impregnation sequential Qingliang Zeng, Zhitao Han, Tingjun Liu, Shoujun Zhang, Shaoqin Sheng, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6991891/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract The use of methanol as an alternative fuel for marine diesel engines increases unregulated CH 3 OH emissions. A series of Pt-modified Cu/SSZ-13 catalysts were prepared using different impregnation method, which selectively catalyzed oxidation of CH 3 OH (CH 3 OH-SCO) to CO 2 and H 2 O. Activity tests showed that Cu/Pt/SSZ-13 catalyst (Pt impregnated first, followed by Cu) displayed exceptional CH 3 OH-SCO performance, achieving 100 % methanol conversion at 150 °C with negligible CO and HCHO byproduct formation (< 5 ppm) across the tested temperature range. Additionally, Cu/Pt/SSZ-13 catalyst exhibited excellent SO 2 resistance and high synergistic activity for simultaneous CH 3 OH and NO x removal. Characterization results demonstrated that Cu/Pt/SSZ-13 catalyst exhibited larger pore size, higher specific surface area, abundant strong alkaline site density and elevated surface-adsorbed oxygen (O ads ) proportion. It was originated from the preferential introduction of Pt and subsequent doping of Cu enhanced the synergistic interaction at the interface of PtO x and CuO species, which facilitated the rapid migration of reactive oxygen species, thus accelerating the methanol dehydrogenation and deep oxidation. In-situ DRIFTS results indicated that Cu/Pt/SSZ-13 inhibited the deposition of formate while promoting the rapid conversion of intermediates such as formaldehyde and formic acid to CO 2 . CH3OH-SCO Cu/Pt/SSZ-13 PtOx CuO formate 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 1. Introduction The utilization of methanol as an alternative fuel in internal combustion engines has gained significant attention due to its carbon-neutral potential and reduced particulate emissions[ 1 ]. However, unburned methanol (CH 3 OH) in engine exhaust poses environmental and health risks[ 2 ]. Selective catalytic oxidation (SCO) was demonstrated as a promising strategy for methanol elimination, enabling the selective oxidation of CH 3 OH (CH 3 OH-SCO) to CO 2 and H 2 O. The core of SCO technology lay in the catalyst, where the design of the catalyst played a pivotal role in determining methanol conversion efficiency and minimizing the production of toxic byproducts (e.g. HCHO, CO). Cu/SSZ-13 had been commercially deployed for selective catalytic reduction (SCR) denitration in exhaust from heavy-duty vehicles and marine engines, owing to its distinctive CHA topology and high specific surface area[ 3 , 4 ]. Consequently, researchers prioritized investigations into its application for SCO reactions[ 5 , 6 ]. The CuO active component exhibited strong oxidation capability, while the SSZ-13 support demonstrated superior CH 3 OH adsorption capacity compared to ZSM-5 and Beta zeolites[ 7 , 8 ]. Nevertheless, Cu/SSZ-13 catalyst suffered from insufficient high-temperature activity and inadequate sulfur resistance during catalytic processes[ 9 ]. Platinum-loaded catalysts were reported to exhibit high activity for the oxidation of methanol and carbon monoxide. Mo et al[ 10 ]. significantly enhanced the methanol oxidation activity of Pt/MnO 2 catalysts by modifying MnO 2 supports with platinum nanoparticles (NPs), compared to pristine MnO 2 . Characterization results revealed that the superior reactivity of Pt/MnO 2 could be attributed to the interfacial interaction between Pt NPs and the MnO 2 support, which modulated the local Pt-Mn coordination environment. It was interaction endowed the catalyst with enhanced low-temperature reducibility, a high concentration of Mn 4+ species, and highly active surface lattice oxygen. Tian et al[ 11 ]. synthesized platinum-loaded ZSM-5 catalysts for the complete oxidation of CO and C 3 H 6 . Pt/ZSM-5 catalyst demonstrated strong metal-support interactions between atomically dispersed Pt species and the ZSM-5 framework. The synergistic effects of PtO x species and Pt-associated lattice oxygen as active centers enabled Pt/ZSM-5 catalyst to achieve complete oxidation with high reaction rates and low activation energy. Notably, despite the exceptional performance of platinum-loaded catalysts, the high cost of platinum remains a critical limitation for their large-scale production and practical application. Thus, doping Cu/SSZ-13 catalysts with trace platinum had become a reliable alternative strategy to obtain high-performance SCO catalysts. Yu et al[ 12 ]. designed a Pt/Cu-SSZ-13 catalyst that exhibited excellent NH 3 -SCO performance under realistic conditions with water vapor, achieving 100% conversion at 200–350°C and over 85% N 2 selectivity across the entire tested temperature range. Liu et al[ 13 ]. developed a PtCu/SSZ-13 catalyst where PtCu alloy nanoparticles were dispersed on the support surface. In this system, Pt species in the alloyed PtCu nanoparticles existed in an electron-rich state, while electron-deficient Cu and isolated Cu 2+ species coexisted on the PtCu-SSZ-13 surface. It was unique alloy structure with modulated oxidation states significantly improved the N 2 selectivity of NH 3 -SCO over PtCu/SSZ-13 catalyst. In this study, we adopted a simple impregnation method utilizing SSZ-13 zeolite as a shared substrate for supporting Pt and Cu. By systematically investigating the effects of impregnation sequence, we elucidated their interaction mechanisms on catalyst performance and the oxidation reaction pathways of CH 3 OH over the catalyst. This work provides crucial guidance for designing high-efficiency CH 3 OH-SCO catalysts with superior activity and minimized byproduct formation. 2. Experimental 2.1 Catalyst preparation Cu/SSZ-13 and Pt/SSZ-13 catalysts were prepared by impregnation; Pt-Cu/SSZ-13 (co-impregnated with Cu and Pt) catalysts were prepared by co-impregnation; Pt/Cu/SSZ-13 (prepared by sequential impregnation of Cu followed by Pt) and Cu/Pt/SS-13 (Pt impregnated first, followed by Cu) catalysts were prepared by distribution impregnation. The detailed preparation protocols were described in Supporting Information. 2.2 Catalyst activity test The evaluation of the catalytic activity was displayed in Supporting Information. 2.3 Catalyst characterization The physical and chemical properties of catalyst samples were characterized with X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDS), N 2 adsorption-desorption, X-ray photoelectron spectra (XPS), Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV-Vis/DRS), H 2 temperature programmed reduction (H 2 -TPR) and CO 2 temperature programmed desorption (CO 2 -TPD). The adsorption behavior of gaseous reactants and in-situ CH 3 OH-SCO reaction processes were investigated via In-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (In-situ DRIFTS) to reveal the possible reaction mechanism. The detailed test conditions were described in Supporting Information. 3. Results and discussion 3.1 CH 3 OH-SCO performance Figure 1 (a) displays the CH 3 OH conversion of Cu/SSZ-13, Pt/SSZ-13, Pt-Cu/SSZ-13, Pt/Cu/SSZ-13, and Cu/Pt/SSZ-13 catalysts within the temperature range of 100–300°C. As shown in Fig. 1 (a), Cu/SSZ-13 catalyst exhibited relatively moderate methanol oxidation performance at low temperatures, with T 100 (the temperature at which 100% CH 3 OH conversion was achieved) of 220°C. The catalytic activity improved for Pt/Cu/SSZ-13 catalyst, which T 100 was reduced to 200°C. It further confirmed that Pt modification enhanced the catalytic activity of Cu/SSZ-13. After changing the impregnation order, Pt-Cu/SSZ-13 catalyst demonstrated a notably higher performance, with T 100 of 180°C. Further optimization of impregnation sequence, Cu/Pt/SSZ-13 catalyst resulted in a remarkable improvement, reaching 100% CH 3 OH conversion even at a low temperature of 160°C. These findings highlight that the impregnation sequence of Pt and Cu significantly influenced the SCO performance of PtCu/SSZ-13 catalysts. Surprisingly, Pt/SSZ-13 catalyst demonstrated exceptional methanol oxidation performance, maintaining 100% CH 3 OH conversion across the entire temperature range of 100–300°C. This superior activity was attributed to the exceptionally strong oxidative capacity of Pt species, which enabled complete low-temperature oxidation of CH 3 OH[ 14 ]. Figure 1 (b) shows the HCHO yields of the five catalysts within the temperature range of 100–300°C. The results indicated that all five catalysts generated small amounts of HCHO byproducts at low temperatures. The HCHO yield order at low temperatures was determined as Pt/Cu/SSZ-13 > Cu/Pt/SSZ-13 > Cu/SSZ-13 > Pt-Cu/SSZ-13 > Pt/SSZ-13. Figure 1 (c) shows the CO yields of the five catalysts within the temperature range of 100–300°C. The results indicated that Cu/SSZ-13 catalyst generated the highest CO yield (4.3%) across the entire temperature window, followed by Pt/Cu/SSZ-13 catalyst with a yield of 2.5%. In contrast, virtually no CO production was detected for Pt/SSZ-13, Pt-Cu/SSZ-13, and Cu/Pt/SSZ-13 catalysts throughout the tested temperature range. The methanol/diesel dual-fuel engine operates in two modes: (1) Diesel mode: Pure diesel was utilized as the sole fuel, analogous to conventional diesel engines. The exhaust characteristics remained consistent with traditional diesel emissions, necessitating aftertreatment systems such as SCR or EGR (Exhaust Gas Recirculation) to comply with Tier III emission standards. (2) Methanol-dominant mode: Methanol served as the primary fuel (accounting for over 90% of consumption), with diesel acting as the ignition fuel[ 15 – 17 ]. In this mode, the exhaust contained both NO x and unburned methanol, which exhibited distinct emission profiles compared to conventional diesel engines. While conventional SCR/EGR systems effectively reduced NO x emissions, the residual methanol required specialized SCO aftertreatment[ 18 ]. To address the emission control demands of marine methanol-fueled engines, we hoped that the developed catalysts were based on realizing efficient SCO removal of methanol and also possessing SCR denitrification functions., thus reducing the complexity and cost of after-treatment systems. Consequently, we further investigated the performance of this series of catalysts for the synergistic catalytic removal of methanol and NO x . The simultaneous NO x reduction and CH 3 OH oxidation performance of the five catalysts was evaluated under co-feeding conditions of 500 ppm CH 3 OH, 500 ppm NH 3 , 500 ppm NO x , 5% O 2 , and balanced N 2 within the temperature range of 100–450°C. As shown in Fig. 2 (a), all Cu-containing catalysts (Cu/SSZ-13, Pt-Cu/SSZ-13, Pt/Cu/SSZ-13, and Cu/Pt/SSZ-13) exhibited nearly identical methanol removal performance, with T 100 of 225°C. In contrast, Pt/SSZ-13 catalyst demonstrated significantly weaker CH 3 OH oxidation activity, with its T 100 increasing to 250°C. Notably, compared to its standalone CH 3 OH-SCO performance, Pt/SSZ-13 catalyst showed a marked decline in methanol conversion efficiency under simultaneous NO x reduction and CH 3 OH oxidation conditions. It could be attributed to competitive adsorption between NH 3 and CH 3 OH on the catalyst surface, which likely suppressed CH 3 OH activation and oxidation over Pt/SSZ-13. Figure 2 (b) showed the HCHO yields of the five catalysts within the temperature range of 100–450°C. All Pt-containing catalysts (Pt/SSZ-13, Pt-Cu/SSZ-13, Pt/Cu/SSZ-13, and Cu/Pt/SSZ-13) generated minimal HCHO (< 5 ppm) only at low temperatures (100–150°C). In contrast, Cu/SSZ-13 catalyst exhibited nearly 100% HCHO yield in the 100–200°C range, indicating that CH 3 OH was predominantly oxidized to HCHO at low temperatures over this catalyst. Figure 2 (c) displayed the CO yields of the five catalysts across the same temperature range. All catalysts produced negligible CO (< 5 ppm) only between 200–250°C. The results demonstrate that under simultaneous NH 3 , NO x , and CH 3 OH co-feeding conditions, Pt-Cu/SSZ-13, Pt/Cu/SSZ-13, and Cu/Pt/SSZ-13 catalysts exhibited superior SCO performance. Figure 2 (d) showed the NO x conversion efficiencies of the five catalysts within the temperature range of 100–450°C. Cu/SSZ-13 catalyst exhibited 100% across a broad temperature window of 185–329°C. After modifying Cu/SSZ-13 with Pt via impregnation to form Pt/Cu/SSZ-13, the denitration performance slightly declined, achieving ~ 100% NO x conversion within a window of 194–316°C. Modifying the impregnation sequence, both Pt-Cu/SSZ-13 and Cu/Pt/SSZ-13 catalysts showed a low-temperature shift in their active windows, with nearly identical NO x conversion profiles (~ 100% within 191–314°C). In contrast, Pt/SSZ-13 catalyst demonstrated a much narrower active window (246–279°C). Figure 2 (e) presented the N 2 selectivity of the five catalysts over the same temperature range. The N 2 selectivity trends mirrored the NO x conversion performance, following the order: Cu/SSZ-13 > Pt/Cu/SSZ-13 > Cu/Pt/SSZ-13 ≈ Pt-Cu/SSZ-13 > Pt/SSZ-13. Notably, the Pt/SSZ-13 catalyst exhibited anomalously low N 2 selectivity (-17%), which was attributed to the over-oxidation of NH 3 to N 2 O by highly oxidative Pt species, resulting in negative selectivity[ 19 ]. These results confirmed that Cu-containing catalysts demonstrated superior SCR performance under simultaneous NH 3 , NO x , and CH 3 OH co-feeding conditions, achieving both high NO x conversion efficiency and favorable N 2 selectivity. Based on the results of CH 3 OH-SCO and simultaneous NO x -Methanol removal, Cu/Pt/SSZ-13 catalyst prepared through sequential impregnation demonstrated dual functionality: (1) exhibited excellent selective catalytic oxidation (SCO) activity at low temperatures, maintaining a CH 3 OH conversion rate exceeding 100% across a broad temperature window of 150–300°C; (2) displayed satisfactory SCR performance. Therefore, Cu/Pt/SSZ-13 catalyst will be selected in the following as the main study for subsequent CH 3 OH-SCO characterization and analysis. Notably, while the Pt/SSZ-13 catalyst showed superior CH 3 OH-SCO activity, its practical application in methanol/diesel dual-fuel engines remained unsuitable due to insufficient SCR performance. Consequently, Pt/SSZ-13 served solely as a control catalyst in this study to elucidate the mechanistic impacts of impregnation sequence on Pt-modified Cu/SSZ-13 catalysts during SCO processes. 3.2 Structural and textural characteristics 3.2.1 XRD Figure 3 shows the XRD characterization results of the synthesized catalysts. Clear diffraction peaks corresponding to the chabazite (CHA) structure of SSZ-13 zeolite were clearly observed for all catalysts, indicating that neither the stepwise nor co-impregnation methods, nor the incorporation of transition or noble metals, disrupted the zeolitic framework[ 20 ]. It confirmed the strong structural stability of SSZ-13 zeolite. High-resolution magnification was performed on regions associated with CuO and Pt species. A weak diffraction peak at 38.7 ° was detected in all Cu-containing catalysts, which was attributed to CuO species, suggesting the formation of small-sized CuO crystallites on their surfaces[ 21 ]. Similarly, diffraction peaks related to the Pt (111) plane were observed in all Pt-containing catalysts, but with very low intensity. It could be attributed to the low Pt loading or the uniform distribution of Pt species without significant aggregation[ 22 ]. 3.2.2 TEM and EDS TEM and EDS images of Cu/SSZ-13 (a), Pt/SSZ-13 (b), Pt-Cu/SSZ-13 (c), Pt/Cu/SSZ-13 (d), and Cu/Pt/SSZ-13 (e) catalysts are shown in Figs. 4 and 5 , respectively. CuO clusters smaller than 2 nm were uniformly distributed on the surface of Cu/SSZ-13 catalyst and the Cu elements were well dispersed[ 23 ]. For Pt/SSZ-13 catalysts, metallic Pt and PtO x species with a lattice spacing of about 0.2 nm were observed on the surface. It indicated that in the Pt-containing catalysts (Pt/SSZ-13, Pt-Cu/SSZ-13, Pt/Cu/SSZ-13, Cu/Pt/SSZ-13), Pt mainly existed as metallic Pt and PtO x on the surface of the carriers or at the entrance of the zeolite pores. In addition, EDS results further verified the high dispersion of Pt species[ 24 ]. For Pt-Cu/SSZ-13 catalyst, some agglomerates due to uneven metal distribution were observed on the surface, which was related to the simultaneous competition of Pt and Cu precursors for the adsorption sites of the carrier. It was hypothesized by EDS mapping that the agglomerates might be the oxide species of Pt and Cu in the form of massive clusters. Pt/Cu/SSZ-13 catalyst boundaries showed a large number of species with inhomogeneous sizes, which may be mainly Pt-CuO composites formed by Pt species in amorphous state and a small number of CuO clusters[ 25 ]. It suggested that the preferential impregnation of Cu with higher loading blocked the microporous entrances or internal channels, which led to the ineffective dispersion of the subsequent Pt impregnation, thus further aggravating the pore blockage. When Cu/Pt/SSZ-13 catalyst was impregnated with Pt first, its precursors preferentially occupied the high-affinity sites on the surface of the SSZ-13 carrier, which provided nucleation centers for the subsequently impregnated Cu and inhibited the aggregation of Cu particles. It was noteworthy that the outer surface of Cu/Pt/SSZ-13 catalyst showed large particles in the form of clumps, which could be hypothesized to be the clumps formed by PtO x and CuO species in combination with the EDS patterns. It was due to the excessive Cu loading, some Cu elements aggregated on the outer surface of the zeolite, the formation of massive CuO species after high temperature calcination, and the formation of Pt-Cu nanocrystals from some Pt species on the surface of SSZ-13 and massive CuO during the process of secondary impregnation. However, such Pt-Cu nanoclusters were mainly embedded in the outer surface of the catalyst and had minimal effect on the active sites on the surface or inside the catalyst zeolite[ 26 ]. 3.2.3 BET The surface physical properties of the synthesized catalysts were investigated via N 2 adsorption-desorption experiments, with the results shown in Fig. 6 . All catalysts exhibited Type I isotherms, characteristic of microporous materials[ 27 ]. Table. 1 summarizes the specific surface areas, micropore areas, average pore diameter, and pore volumes of the catalysts. The order of specific surface area and microporous area size was Pt/SSZ-13 > Cu/Pt/SSZ-13 > Pt/Cu/SSZ-13 > Pt-Cu/SSZ-13 > Cu/SSZ-13, and the pore volume and pore diameter were in the following order: Cu/SSZ-13 > Cu/Pt/SSZ-13 > Pt-Cu/SSZ-13 > Pt/SSZ-13 > Pt/Cu/SSZ-13. Pt/SSZ-13 catalyst exhibited a high specific surface area (566.5 m 2 /g), suggesting that low-loading Pt was dispersed on the support surface via strong interactions with active sites (Si-O-Al − )[ 28 ]. Cu/SSZ-13 catalyst displayed a lower specific surface area and micropore area due to severe Cu aggregation and pore blockage at high Cu loadings. For Pt/Cu/SSZ-13 catalyst, the high Cu loading nearly completely blocked the micropores, and subsequently impregnated Pt primarily existed in an oxidized state (PtO x ) on the catalyst surface. It indicated that PtO x species could promote Cu dispersion, thereby alleviating micropore blockage. Consequently, the specific surface area and micropore area of Pt/Cu/SSZ-13 catalyst increased compared to Cu/SSZ-13. When the impregnation sequence was altered (Pt-Cu/SSZ-13, co-impregnation), the specific surface area and micropore area slightly decreased relative to Pt/Cu/SSZ-13, implying that competitive adsorption between Pt and Cu precursors during co-impregnation weakened Pt’s inhibitory effect on Cu aggregation[ 29 ]. Optimizing the impregnation sequence, the specific surface area, pore volume and pore size of Cu/Pt/SSZ-13 catalysts impregnated with Pt first and Cu later were significantly enhanced. This improvement was attributed to the preferential dispersion of PtO x species on the support surface during the initial impregnation step, forming highly dispersed nanoparticles. Subsequently deposited CuO clusters covered the Pt species, while the strong anchoring effect of Pt suppressed Cu agglomeration, reducing metal particle size and mitigating micropore blockage[ 30 ]. In summary, among Pt-modified Cu/SSZ-13 catalysts with different impregnation sequences, the adoption of the order of preferential impregnation of Pt followed by Cu impregnation could result in Cu/Pt/SSZ-13 catalyst having larger pore diameters, higher specific surface areas and microporous areas at the same time, which could expose more active sites and exhibit excellent adsorption and catalytic abilities. Table 1 BET surface area and pore structure results of prepared catalysts. Catalysts S BET (m 2 /g) Micropore Area (m 2 /g) Average pore Diameter (nm) Pore Volume (cm 3 /g) Cu/SSZ-13 461.4 434.5 2.578 0.228 Pt/SSZ-13 566.5 539.1 2.290 0.042 Pt-Cu/SSZ-13 475.3 449.6 2.375 0.045 Pt/Cu/SSZ-13 488.3 459.5 2.283 0.038 Cu/Pt/SSZ-13 516.6 505.9 2.508 0.068 3.2.4 UV-Vis/DRS UV-vis/DRS analysis of the prepared catalysts was carried out to investigate the chemical state of catalyst surface ions and the results were shown in Fig. 7 . For Cu-containing catalysts, the two peaks observed in the wavelength range of 200–300 nm were likely associated with charge transfer from stable Cu + and isolated Cu 2+ ions to O 2− , suggesting partial incorporation of Cu + and Cu 2+ ions within the SSZ-13 zeolite framework[ 31 ]. The broad band at 600–800 nm corresponded to the d-d orbital transition of Cu 2+ ions induced by CuO species[ 32 , 33 ]. In the case of Pt-containing catalysts, the peak appearing between 300–350 nm was attributed to charge transfer in PtO x species[ 34 ]. Among the five investigated samples, Cu/Pt/SSZ-13 exhibited significantly higher intensities for all five characteristic signals compared to other catalysts, indicating substantial coexistence of PtO x , Cu + , Cu 2+ , and CuO species when adopting the sequential impregnation of Pt followed by Cu. It was observation suggested that the synergistic interaction between Pt and Cu species played a critical role in enhancing SCO performance of various Pt-modified Cu/SSZ-13 catalysts. 3.2.4 XPS To investigate the surface elemental valence states of Pt-modified Cu/SSZ-13 catalysts with different impregnation sequences, XPS analysis was conducted on the synthesized catalysts, as shown in Fig. 8 . The surface relative contents of Cu and O elements were determined through integral calculations of their characteristic peaks, with results summarized in Table. 2. As shown in Fig. 8 (a), the Pt 4d spectra of Pt-containing catalysts were deconvoluted into two sub-peaks. The higher binding energy peak at ~ 333 eV was assigned to oxidized Pt species (Pt 2+ or PtO x )[ 35 ]. For Pt/SSZ-13, PtO x species exhibited a highly dispersed state, resulting in an elevated binding energy of 333.59 eV. Pt/Cu/SSZ-13 catalyst displayed the lowest binding energy, implying electron enrichment at Pt sites induced by preferential Cu loading, where Cu likely acted as an electron donor to reduce the oxidation state of Pt[ 36 ]. Pt-Cu/SSZ-13 led to a higher binding energy, which might correlate with metal agglomeration. Competition between Pt and Cu precursors for active sites during impregnation promoted particle growth, thereby decreasing the d-orbital electron density of Pt[ 37 ]. For the optimized Cu/Pt/SSZ-13 catalyst, the binding energy was intermediate between Pt/SSZ-13 and Pt/Cu/SSZ-13, suggested that subsequent Cu overlayers only partially modified the electronic structure of pre-loaded Pt. This Cu overlayer likely optimized the adsorption strength of SCO reaction intermediates (e.g., formaldehyde, formic acid) by tuning the d-band center of Pt, thereby enhancing catalytic selectivity[ 38 ]. Notably, all Pt-containing catalysts exhibited a lower binding energy peak at ~ 316 eV, corresponding to metallic Pt 0 , indicating partial reduction during calcination or pretreatment. The minor binding energy shifts (ΔBE < 0.8 eV) among Pt 0 signals implied weak Pt-Cu interactions dominated by physical coexistence or subtle electronic effects rather than strong alloying[ 37 ]. As shown in Fig. 8 (b), the Cu 2p spectra of Cu-containing catalysts showed peaks at ~ 935.3 eV and 955.8 eV with satellite features, characteristic of surface Cu 2+ species (CuO). Peaks at ~ 933.9 eV and 953.5 eV were attributed to Cu 0 and Cu + [ 39 ]. In Pt-Cu/SSZ-13, competition between Pt and Cu precursors for active sites favored CuO formation (64.4% Cu 2+ ). For Pt/Cu/SSZ-13, pre-loaded Cu occupied high-affinity sites in SSZ-13, forcing subsequent Pt deposition onto suboptimal external sites and generating partially reduced Cu species (Cu 0 clusters), which decreased the Cu 2+ proportion to 61.7%. The strong anchoring effect of Pt in Cu/Pt/SSZ-13 stabilized Cu + species (Cu 2 O) via electronic interactions, yielding the lowest Cu 2+ content (56.2%). The surface oxygen species significantly influenced the redox properties of the catalysts. Figure 8 (c) displayed the O 1s XPS spectra of the five catalysts. Through spectral deconvolution, two distinct oxygen species were identified on the catalyst surfaces: the higher binding energy peak corresponded to chemisorbed oxygen species (O 2− or O − , denoted as O ads ), while the lower binding energy peak was attributed to lattice oxygen (O 2− , denoted as O latt ). O ads participated more readily in redox reactions compared to O latt , which remained tightly bound within the zeolite framework[ 40 ]. Consequently, a higher O ads / (O ads + O latt ) ratio correlated with enhanced redox activity. As summarized in Table. 2, among the three Pt-modified Cu/SSZ-13 catalysts prepared with different impregnation sequences, Cu/Pt/SSZ-13 exhibited the highest surface-adsorbed oxygen ratio (91.4%). It could be attributed to PtO x anchoring at high-energy surface sites, which enhanced oxygen mobility, reduced oxygen vacancy formation energy, and facilitated oxygen activation, collectively improving redox capability[ 41 , 42 ]. Table. 2. XPS data of all catalysts. 3.3 Redox properties 3.3.1 O 2 -TPD O 2 -TPD analysis was conducted to investigate oxygen species in the five catalysts, with results shown in Fig. 9 . The O 2 desorption peaks in the 200–500°C range were attributed to O ads , while those in the 500–900°C range corresponded to O latt . All catalysts exhibited significantly higher intensity for surface-adsorbed oxygen than lattice oxygen. Previous studies reported that adsorbed oxygen species (e.g., O − , O 2 − ) directly interact with methanol or its intermediates (e.g., CO*, HCOO − ), facilitating C-H bond cleavage and complete oxidation to CO 2 , suggesting the dominant role of adsorbed oxygen in methanol catalytic oxidation[ 43 ]. The desorption peaks of O ads shifted to lower-temperature regions in the order: Pt/SSZ-13 > Pt-Cu/SSZ-13 ≈ Pt/Cu/SSZ-13 ≈ Cu/Pt/SSZ-13 > Cu/SSZ-13, indicating faster reaction kinetics of adsorbed oxygen on Pt-containing catalysts. Furthermore, although Pt-modified Cu/SSZ-13 catalysts with different impregnation sequences showed nearly identical peak positions for adsorbed oxygen, their relative abundance (calculated via curve integration) ranked in descending order: Cu/Pt/SSZ-13 > Pt-Cu/SSZ-13 > Pt/Cu /SSZ-13. The sequential impregnation strategy optimized both oxygen mobility and active site distribution, explaining the superior SCO performance of Cu/Pt/SSZ-13 observed in catalytic testing. These observations aligned with XPS results. 3.3.1 H 2 -TPR The redox properties of the five catalysts were investigated via H 2 -TPR experiments, with the results shown in Fig. 10 and Table. 3. For Pt/SSZ-13 catalyst, two weak peaks were observed: the first peak was attributed to the reduction of minor isolated Pt 2+ ions exchanged within zeolite channels; the second peak corresponded to the reduction of PtO x species to metallic Pt 0 , which likely resided on the zeolite surface or near 6-membered ring (6-MR) pore entrances[ 28 ]. In Cu/SSZ-13, Pt/Cu/SSZ-13, Cu/Pt/SSZ-13, and Pt-Cu/SSZ-13 catalysts, four distinct reduction peaks were identified: Peak 1: Reduction of isolated Cu 2+ ions near 8-membered ring (8-MR) windows and within CHA cages. Peak 2: Single-step reduction of CuO clusters to metallic Cu 0 . Peak 3: Reduction of Cu 2+ species localized near or at 6-MR pore entrances[ 44 ]. Peak 4: reduction of minor PtO x species to metallic Pt 0 . Intriguingly, the total H 2 consumption of Pt/SSZ-13 and Cu/SSZ-13 catalysts showed an inverse correlation with their CH 3 OH-SCO activities, suggesting that total reducibility alone was not the decisive factor for methanol oxidation performance[ 45 ]. Notably, Cu/Pt/SSZ-13 catalyst showed significantly stronger H 2 consumption for the reduction peaks corresponding to CuO and PtO x compared to Pt/Cu/SSZ-13 and Pt-Cu/SSZ-13. It was observation indicated enhanced synergistic catalytic oxidation of methanol by CuO and PtO x species in Cu/Pt/SSZ-13. The optimized synergy accounted for the superior CH 3 OH-SCO performance of Cu/Pt/SSZ-13, where Pt 2+ facilitated the activation of CuO, while CuO stabilized Pt in an oxidized state critical for methanol C-H bond cleavage. The sequential Pt-then-Cu impregnation strategy enabled spatial and electronic coupling between Pt and Cu species, establishing a hierarchically structured active site system that maximized oxygen migration efficiency during catalytic cycles. These findings revealed that PtO x -CuO interfacial interaction served as the key driving force for complete methanol oxidation. Table 3 H 2 -TPR data of Cu 2.5 /SSZ-13, Cu 10 /SSZ-13 and Cu 12.5 /SSZ-13 catalysts Samples H 2 consumption (mmol / g) Peak 1 Peak 2 Peak 3 Peak 4 Total Cu/SSZ-13 0.84 1.30 0.37 - 2.56 Pt/SSZ-13 0.19 0.65 - - 0.84 Pt-Cu/SSZ-13 0.61 0.70 0.72 0.11 2.14 Pt/Cu/SSZ-13 0.55 0.64 0.05 - 1.24 Cu/Pt/SSZ-13 0.71 0.88 0.36 0.32 2.27 3.4 Surface acidity 3.4.1 CO 2 -TPD The surface basicity of the synthesized catalysts was investigated via CO 2 -TPD experiments to evaluate the effects of impregnation sequences on Pt-modified Cu/SSZ-13 catalysts, with results shown in Fig. 11 . The quantitative analysis of the total alkalinity on the catalyst surface was calculated from the integration of the CO 2 -TPD curve and the results are listed in Table 4 . All catalysts exhibited desorption peaks in the 100–350°C and 350–600°C temperature ranges. Based on prior reports, the low-temperature peak (< 350°C) was attributed to weak basic sites corresponding to CO 2 desorption from hydrated hydroxyl groups. The CO 2 desorption peaks above 350°C were attributed to strongly basic sites, corresponding to the desorption of CO 2 adsorbed on the free hydroxyl groups on the catalyst surface[ 46 ]. Monometallic Pt/SSZ-13 and Cu/SSZ-13 catalysts primarily displayed weak basicity. In contrast, bimetallic catalysts showed enhanced peaks for strong basic sites but significantly reduced total basicity compared to monometallic counterparts, suggesting competitive or synergistic interactions between Pt and Cu species that altered hydroxyl group distributions. Notably, Pt-modified Cu/SSZ-13 catalysts with different impregnation sequences exhibited comparable total basicity. Among them, Cu/Pt/SSZ-13 catalyst demonstrated the highest concentration of strong basic sites (0.3 mmol/g). This increased population of strong basic sites likely facilitated methanol activation via C-H bond polarization, thereby enhancing SCO performance[ 47 , 48 ]. The sequential Pt-then-Cu strategy optimized the balance between acidic and basic sites, favoring the formation of stable reaction intermediates during CH 3 OH oxidation. Table 4 CO 2 -TPD results of all catalysts. Catalysts Acid amount (mmol/g) Total acidity (mmol/g) Peak Ⅰ Peak Ⅱ Cu/SSZ-13 0.77 0.07 0.84 Pt/SSZ-13 0.46 0.03 0.49 Pt-Cu/SSZ-13 0.12 0.32 0.44 Pt/Cu/SSZ-13 0.18 0.22 0.4 Cu/Pt/SSZ-13 0.09 0.35 0.44 3.5. Experimental In-situ DRIFTS 3.5.1 Catalyst preparation Adsorption of CH 3 OH + O 2 In-situ DRIFTS experiments of CH 3 OH + O 2 co-adsorption on Cu/Pt/SSZ-13 catalyst was conducted to investigate the types of methanol-derived species adsorbed on the catalyst surface at different temperatures, as shown in Fig. 12 . A negative peak at 3668 cm − 1 corresponded to the O-H stretching vibration of surface hydroxyl groups[ 49 ]. Characteristic peaks near 2959 cm − 1 and 2846 cm − 1 were attributed to C-H stretching vibrations of methanol and methoxy (CH 3 O − ) species, respectively[ 50 ]. The peak at 2154 cm − 1 aligned with gaseous CO 2 formation, while the feature at 2129 cm − 1 originated from adsorbed CO[ 51 ]. Peaks at 1678 cm − 1 and 1655 cm − 1 were assigned to C = O stretching vibrations of aldehyde (-CHO) and formic acid (HCOOH) species, respectively[ 52 ]. The diminishing intensity of formic acid-related peaks suggested rapid decomposition of formate intermediates or direct oxidation of formaldehyde to CO 2 , bypassing intermediate stages. The peak near 1585 cm − 1 arose from asymmetric O-C-O stretching of carboxylate (COO − ) species, while the feature at 1470 cm − 1 corresponded to symmetric O-C-O stretching of formate (HCOO − ) intermediates, both critical in methanol oxidation pathways[ 53 ]. The emergence of a carbonate (CO 3 2− ) peak at 1509 cm − 1 at 200°C indicated deep oxidation of methanol[ 53 ]. A prominent peak at 1295 cm − 1 represented C-O stretching of methanol, while features near 1250 cm − 1 and 1120 cm − 1 were linked to C-O vibrations of methoxy (CH 3 O − ) species[ 54 ]. The progressive enhancement of CH 3 O − -related peaks across 50–350°C demonstrated the persistent involvement of methoxy species throughout the SCO reaction. This observation implied that Pt doping facilitated direct dehydrogenation of methanol to methoxy species, rather than relying on surface hydroxyl groups or oxygen vacancies. Such a pathway shortened the reaction route, enabling rapid methanol removal at low temperatures. In-situ DRIFTS experiments were conducted to investigate the transient CH 3 OH-SCO reaction of co-adsorbed CH 3 OH and O 2 on the Cu/Pt/SSZ-13 catalyst at 200°C, with results shown in Fig. 13 . As shown in Fig. 13 (b), the peak intensities attributed to methanol species in the in-situ spectra of Pt/Cu/SSZ-13 catalyst gradually increased with reaction time (1–60 min), indicating that the catalyst continued to adsorb methanol at 200°C, which implied insufficient adsorption functionality. From Fig. 13 , the peaks corresponding to methoxy and formate species progressively intensified for all three catalysts as the reaction time increased, further confirming that methoxy and formate were key intermediates in the CH₃OH-SCO reaction. Notably, Cu/Pt/SSZ-13 catalyst exhibited weaker formate-related peaks, suggesting that it partially bypassed the formate generation stage, thereby suppressing formic acid accumulation and directly promoting complete methanol oxidation to CO 2 . The rapid enrichment of methoxy and formate species indicated that the reaction pathway predominantly followed a direct dehydrogenation-oxidation mechanism, rather than sequential carboxylate-mediated steps. It was behavior aligned with the catalyst’s high low-temperature SCO efficiency, as suppressing formate accumulation minimized intermediate poisoning and accelerated overall reaction kinetics. The Pt-first impregnation sequence enhanced the synergy between Pt (facilitating C-H bond cleavage) and CuO (enhancing oxygen mobility), thereby enabling this simplified reaction pathway[ 55 , 56 ]. 3.5.2 Discussion on reaction mechanism Proposed Methanol Catalytic Oxidation Pathway (Based on In Situ DRIFTS) Step 1: Methanol Adsorption and Dehydrogenation The high dehydrogenation activity of Pt accelerated methanol conversion to methoxy species, while the synergy between Cu and Pt synergistically catalyzed the reaction, lowering the activation energy. CH 3 OH → CH 3 O − + H + Step 2: Rapid Methoxy - to - Formaldehyde Conversion Pt promoted surface oxygen activation (O 2 → 2O − ), facilitating methoxy dehydrogenation. CH 3 O − → HCHO + H + Step 3: Efficient Formaldehyde - to - Formic acid Conversion Formaldehyde reacted with surface hydroxyl groups to form formic acid, which subsequently dissociated into formate species. HCHO + H 2 O → HCOOH HCOOH → HCOO − + H + Step 4: Rapid Decomposition of Formate Pt's strong oxidizing ability inhibited formate accumulation and promoted its rapid conversion to CO 2 . HCOO − + 1/2 O 2 → CO 2 + H 2 O + e − Parallel Pathways: CO Oxidation: Pt preferentially adsorbed and rapidly oxidized CO. CO + O − → CO 2 Enhanced Carbonate Decomposition: Strong Pt-Cu interfacial interactions promoted CO 3 2− decomposition. CO 3 2− → CO 2 + O 2 − 4. Conclusion Cu/Pt/SSZ-13 catalyst, prepared by sequential impregnation (Pt first, Cu second), selectively oxidized methanol to CO 2 and H 2 O at 160°C with minimal byproduct formation, thereby effectively controlling CH 3 OH emissions from methanol-fueled engines. Additionally, Cu/Pt/SSZ-13 catalyst demonstrated excellent SO 2 resistance and maintained high activity during simultaneous denitration and methanol removal, highlighting its potential as a multifunctional catalyst. Characterization studies revealed that Pt was preferentially dispersed on the carrier surface in the form of PtO x species. Meanwhile, the strong anchoring effect of Pt promoted the uniform dispersion of the subsequently introduced small-sized CuO nanoclusters. The rational distribution of Pt and Cu species endowed the Cu/Pt/SSZ-13 catalyst with a larger pore size and higher specific surface area, providing ideal pathways for reactant diffusion and intermediate conversion. Furthermore, the Cu/Pt/SSZ-13 catalyst exhibited a high density of strong alkaline sites and an elevated proportion of surface-adsorbed oxygen, which originated from the synergistic interfacial effects between PtO x and CuO species. It was synergy facilitated the rapid generation of active oxygen species, accelerating methanol dehydrogenation and deep oxidation. In situ DRIFTS results confirmed that Cu/Pt/SSZ-13 catalyst suppressed the deposition of formate intermediates while promoting the rapid conversion of formaldehyde intermediates to CO 2 . This study demonstrated the efficient methanol removal performance of a cost-effective Pt-modified Cu/SSZ-13 catalyst, which provides a new strategy for designing CH 3 OH-SCO catalysts that can effectively reduce CH 3 OH emissions from methanol/diesel engines while minimizing undesirable by-products during CH 3 OH oxidation. Abbreviations SCO Selective catalytic oxidation CH 3 OH-SCO selectively catalyzed oxidation of CH 3 OH NH 3 -SCO Selective catalytic oxidation of ammonia XRD X-ray diffraction SEM Scanning electron microscopy EDS Energy dispersive X-ray XPS X-ray photoelectron spectra UV-Vis/DRS Ultraviolet–Visible Diffuse Reflectance Spectroscopy H 2 -TPR H 2 temperature programmed reduction CO 2 -TPD CO 2 temperature programmed desorption In-situ DRIFTS In-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy SCR selective catalytic reduction NPs nanoparticles EGR Exhaust Gas Recirculation CHA chabazite Declarations Acknowledgments The authors gratefully acknowledge for the financial support from the Guangdong Province Natural Resources Project (2022-32) and the National Natural Science Foundation of China (52271356). Author Contributions Qingliang Zeng: Conceptualization, Methodology, Formal analysis, Data curation, Writing-original & draft. Zhitao Han: Methodology, Writing-review & editing, Project administration, Funding acquisition. Tingjun Liu: Investigation, Resources. Shoujun Zhang: Investigation, Resources. Shaoqin Sheng: Investigation, Resources. Liangzheng Lin: Investigation, Resources. Junhao Jing: Investigation, Resources. Sihan Yin: Investigation, Resources. Funding This work was supported by Guangdong Province Natural Resources Project (2022-32), National Natural Science Foundation of China (52271356). Data Availability No datasets were generated or analysed during the current study. Competing Interests The authors declare no competing interests. Ethics and Consent to Participate Not applicable. Consent for Publication Not applicable. References Tian Z, Wang Y, Zhen X, Liu Z (2022) Fuel 320:123902. Ma B, Yao A, Yao C, Wang W, Ai Y (2021) Appl Energy 300:117355. Mohan S, Dinesha P, Kumar S (2020) Chem Eng J 384:123253. Wang Y, Zhu T, Zhao Y, Hao X (2024) J. Chin Chem Soc. 71:1448-1463. 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Supplementary Files Graphicalabstract.jpg SupportingInformation.docx Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 22 Jul, 2025 Reviews received at journal 22 Jul, 2025 Reviews received at journal 14 Jul, 2025 Reviewers agreed at journal 08 Jul, 2025 Reviewers agreed at journal 07 Jul, 2025 Reviewers invited by journal 07 Jul, 2025 Editor assigned by journal 01 Jul, 2025 Submission checks completed at journal 01 Jul, 2025 First submitted to journal 27 Jun, 2025 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-6991891","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":483335998,"identity":"a54c89c1-689d-4ebd-986d-f6bd1d41de2d","order_by":0,"name":"Qingliang Zeng","email":"","orcid":"","institution":"Dalian Maritime University","correspondingAuthor":false,"prefix":"","firstName":"Qingliang","middleName":"","lastName":"Zeng","suffix":""},{"id":483335999,"identity":"2abce994-8fec-406c-9e72-33393359153c","order_by":1,"name":"Zhitao Han","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAuElEQVRIiWNgGAWjYBACAzBZwSwDpnmI1nLgDDMPiVoOtpGixZz97OHPH+dZ8+jOSGB88LaNQd6ckBbLnrwEg4Pb0nnMbiQwG85tYzDc2UDIYQdyDBIObjsM0sImzdvGkGBwgJCW828MDhycA9bC/ps4LTdyDBsONkBsYSZSyxtjhjPHgH4587BZcs45CcMNhB2WY/yhosZazux48sEPb8ps5AnaggQYG4CEBPHqR8EoGAWjYBTgBgA3E0EMG3FI9AAAAABJRU5ErkJggg==","orcid":"","institution":"Dalian Maritime University","correspondingAuthor":true,"prefix":"","firstName":"Zhitao","middleName":"","lastName":"Han","suffix":""},{"id":483336000,"identity":"4b47f643-385d-4c44-90b5-5da4def0783c","order_by":2,"name":"Tingjun Liu","email":"","orcid":"","institution":"Dalian Maritime University","correspondingAuthor":false,"prefix":"","firstName":"Tingjun","middleName":"","lastName":"Liu","suffix":""},{"id":483336001,"identity":"4aea812a-f9b5-4d56-8003-4d1ff2161cb3","order_by":3,"name":"Shoujun Zhang","email":"","orcid":"","institution":"Guangdong Ocean University","correspondingAuthor":false,"prefix":"","firstName":"Shoujun","middleName":"","lastName":"Zhang","suffix":""},{"id":483336002,"identity":"9c9ef714-e3fa-4dec-92fd-114b1b87fa84","order_by":4,"name":"Shaoqin Sheng","email":"","orcid":"","institution":"Guangzhou Shipyard International Company Ltd","correspondingAuthor":false,"prefix":"","firstName":"Shaoqin","middleName":"","lastName":"Sheng","suffix":""},{"id":483336003,"identity":"8cbd81ef-78f4-4480-aa90-d06acc45c5d0","order_by":5,"name":"Liangzheng Lin","email":"","orcid":"","institution":"Dalian Maritime University","correspondingAuthor":false,"prefix":"","firstName":"Liangzheng","middleName":"","lastName":"Lin","suffix":""},{"id":483336004,"identity":"a0ff3c09-3ec9-49aa-a5ba-20030e16208c","order_by":6,"name":"Junhao Jing","email":"","orcid":"","institution":"Dalian Maritime University","correspondingAuthor":false,"prefix":"","firstName":"Junhao","middleName":"","lastName":"Jing","suffix":""},{"id":483336005,"identity":"0bde6e5d-c433-4680-bd53-98105a756e99","order_by":7,"name":"Sihan Yin","email":"","orcid":"","institution":"Dalian Maritime University","correspondingAuthor":false,"prefix":"","firstName":"Sihan","middleName":"","lastName":"Yin","suffix":""}],"badges":[],"createdAt":"2025-06-27 13:08:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6991891/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6991891/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":86479893,"identity":"1762dc5f-8dc1-4790-993f-1d3c018c860e","added_by":"auto","created_at":"2025-07-11 07:33:25","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":434038,"visible":true,"origin":"","legend":"\u003cp\u003e(a) CH\u003csub\u003e3\u003c/sub\u003eOH conversion, (b) HCHO yield and (c) CO yield of all catalysts. (Reaction conditions: 0.2 mL catalyst, [CH\u003csub\u003e3\u003c/sub\u003eOH] = 500 ppm, [O\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003e \u003c/sub\u003e=\u003csub\u003e \u003c/sub\u003e5 vol.%, balance with N\u003csub\u003e2\u003c/sub\u003e, total flow rate = 200 mL×min\u003csup\u003e-1\u003c/sup\u003e and GHSV =60,000 h\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/11894a42bd07ca071e870ed9.png"},{"id":86479894,"identity":"9f3fa387-c730-4b27-b7a1-5a049400abb6","added_by":"auto","created_at":"2025-07-11 07:33:25","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":701209,"visible":true,"origin":"","legend":"\u003cp\u003e(a) CH\u003csub\u003e3\u003c/sub\u003eOH conversion, (b) HCHO yield, (c) CO yield (d) NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e conversion and (e) N\u003csub\u003e2\u003c/sub\u003e selectivity yield of all catalysts. (Reaction conditions: 0.2 mL catalyst, [CH\u003csub\u003e3\u003c/sub\u003eOH] = [NH\u003csub\u003e3\u003c/sub\u003e] = [NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e] = 500 ppm, [O\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003e \u003c/sub\u003e=\u003csub\u003e \u003c/sub\u003e5 vol.%, balance with N\u003csub\u003e2\u003c/sub\u003e, total flow rate = 200 mL×min\u003csup\u003e-1\u003c/sup\u003e and GHSV =60,000 h\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/a9adef81f4e426b024406a6b.png"},{"id":86479895,"identity":"918d7bd9-159a-42e9-ac6c-818fe8c5f5b6","added_by":"auto","created_at":"2025-07-11 07:33:25","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":136273,"visible":true,"origin":"","legend":"\u003cp\u003eXRD patterns of different catalysts.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/0b5379fea711784601aa7933.png"},{"id":86481217,"identity":"05a1ef24-8261-48e9-ad38-a8dda6447bfe","added_by":"auto","created_at":"2025-07-11 07:49:25","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":328653,"visible":true,"origin":"","legend":"\u003cp\u003eTEM images of (a) Cu/SSZ-13, (b) Pt/SSZ-13, (c) Pt-Cu/SSZ-13, (d) Pt/Cu/SSZ-13 and (e) Cu/Pt/SSZ-13 catalysts\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/e5d21fe269e5babddaadaddb.png"},{"id":86479896,"identity":"e7a0adeb-00ce-4afd-b4e4-767348c24d59","added_by":"auto","created_at":"2025-07-11 07:33:25","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":342515,"visible":true,"origin":"","legend":"\u003cp\u003eEDS images of (a) Cu/SSZ-13, (b) Pt/SSZ-13, (c) Pt-Cu/SSZ-13, (d) Pt/Cu/SSZ-13 and (e) Cu/Pt/SSZ-13 catalysts\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/5bdb65bf16bddb6e6e91b7ed.png"},{"id":86479899,"identity":"1494a423-6b8b-404a-aae9-d40ceb92738e","added_by":"auto","created_at":"2025-07-11 07:33:25","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":143846,"visible":true,"origin":"","legend":"\u003cp\u003eN\u003csub\u003e2\u003c/sub\u003e adsorption-desorption isotherms of different catalysts\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/b19a63a91316e482d01421cd.png"},{"id":86479908,"identity":"4d9771ca-63df-43d2-8a0e-abe0915577c8","added_by":"auto","created_at":"2025-07-11 07:33:25","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":149110,"visible":true,"origin":"","legend":"\u003cp\u003eUV-Vis/DRS spectera of different catalysts in the range of 200-800 ºC.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/61a6921edda9a2182b2f1a65.png"},{"id":86480852,"identity":"2488655c-0e7e-4515-9a5a-0155a13fbeac","added_by":"auto","created_at":"2025-07-11 07:41:25","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":476042,"visible":true,"origin":"","legend":"\u003cp\u003eXPS spectra of (a) Cu 2\u003cem\u003ep\u003c/em\u003e, (b) O \u003cem\u003e1s\u003c/em\u003eover all catalysts.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/a802cf7fd92643da953992e2.png"},{"id":86479905,"identity":"af0a95a0-88c1-4d45-9c39-12573e405a59","added_by":"auto","created_at":"2025-07-11 07:33:25","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":131929,"visible":true,"origin":"","legend":"\u003cp\u003eO\u003csub\u003e2\u003c/sub\u003e-TPD profiles of all catalysts in the range of 100-900 ºC.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/dd81d18ecdfd667e57e61c7e.png"},{"id":86480849,"identity":"4e3240cf-94e8-4802-ab3f-4d5837f0f884","added_by":"auto","created_at":"2025-07-11 07:41:25","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":123021,"visible":true,"origin":"","legend":"\u003cp\u003eH\u003csub\u003e2\u003c/sub\u003e-TPR profiles of all catalysts in the range of 100-800 ºC.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/9007e78057fb07b3b7ac0a7f.png"},{"id":86481221,"identity":"1d49c711-8921-4b5a-869e-a54a29f46f42","added_by":"auto","created_at":"2025-07-11 07:49:26","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":148495,"visible":true,"origin":"","legend":"\u003cp\u003eCO\u003csub\u003e2\u003c/sub\u003e-TPD curves of all catalysts in the range of 100-500 ºC.\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/c9abf8e0a52f0430abe7c257.png"},{"id":86479915,"identity":"7bb02348-75d1-48de-8764-88de1156b63b","added_by":"auto","created_at":"2025-07-11 07:33:26","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":448622,"visible":true,"origin":"","legend":"\u003cp\u003eIn-situ DRIFTS spectra of (a) Pt-Cu/SSZ-13, (b) Pt/Cu/SSZ-13 and (c) Cu/Pt/SSZ-13 catalysts at different temperatures. Condition: [CH\u003csub\u003e3\u003c/sub\u003eOH] = 500 ppm, [O\u003csub\u003e2\u003c/sub\u003e] = 5 vol.% and N\u003csub\u003e2\u003c/sub\u003e as balance gas\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/fda5002361661c0cbacf5d68.png"},{"id":86483207,"identity":"1da354a3-6d38-4f18-a1a2-58b40117ae8f","added_by":"auto","created_at":"2025-07-11 07:57:26","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":436757,"visible":true,"origin":"","legend":"\u003cp\u003eIn-situ DRIFTS spectra of (a) Pt-Cu/SSZ-13, (b) Pt/Cu/SSZ-13 and (c) Cu/Pt/SSZ-13 catalysts at 200 ℃. Condition: [CH\u003csub\u003e3\u003c/sub\u003eOH] = 500 ppm, [O\u003csub\u003e2\u003c/sub\u003e] = 5 vol.% and N\u003csub\u003e2\u003c/sub\u003e as balance gas\u003c/p\u003e","description":"","filename":"13.png","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/0c47ef074dfb89e0ffdb0911.png"},{"id":87466850,"identity":"7dacdd8e-f3e6-4599-868d-e72e7392447e","added_by":"auto","created_at":"2025-07-24 07:35:15","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4155169,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/399516fe-75be-4616-bf95-4143774228e5.pdf"},{"id":86483206,"identity":"c43df7ee-7127-421e-9a38-3d26cdab4160","added_by":"auto","created_at":"2025-07-11 07:57:25","extension":"jpg","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":2121415,"visible":true,"origin":"","legend":"","description":"","filename":"Graphicalabstract.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/18cc2df9599a65f7bdc17cb7.jpg"},{"id":86481218,"identity":"789b2b80-ea8f-4684-afc1-5eb2945c09d0","added_by":"auto","created_at":"2025-07-11 07:49:25","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":509816,"visible":true,"origin":"","legend":"","description":"","filename":"SupportingInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-6991891/v1/51433abb30d809eb91db7325.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Selective catalytic oxidation of methanol on Pt-modified Cu/SSZ-13 zeolites: A strategy to change the catalytic performance by impregnation sequential","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe utilization of methanol as an alternative fuel in internal combustion engines has gained significant attention due to its carbon-neutral potential and reduced particulate emissions[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. However, unburned methanol (CH\u003csub\u003e3\u003c/sub\u003eOH) in engine exhaust poses environmental and health risks[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Selective catalytic oxidation (SCO) was demonstrated as a promising strategy for methanol elimination, enabling the selective oxidation of CH\u003csub\u003e3\u003c/sub\u003eOH (CH\u003csub\u003e3\u003c/sub\u003eOH-SCO) to CO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO. The core of SCO technology lay in the catalyst, where the design of the catalyst played a pivotal role in determining methanol conversion efficiency and minimizing the production of toxic byproducts (e.g. HCHO, CO).\u003c/p\u003e\u003cp\u003eCu/SSZ-13 had been commercially deployed for selective catalytic reduction (SCR) denitration in exhaust from heavy-duty vehicles and marine engines, owing to its distinctive CHA topology and high specific surface area[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Consequently, researchers prioritized investigations into its application for SCO reactions[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The CuO active component exhibited strong oxidation capability, while the SSZ-13 support demonstrated superior CH\u003csub\u003e3\u003c/sub\u003eOH adsorption capacity compared to ZSM-5 and Beta zeolites[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Nevertheless, Cu/SSZ-13 catalyst suffered from insufficient high-temperature activity and inadequate sulfur resistance during catalytic processes[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Platinum-loaded catalysts were reported to exhibit high activity for the oxidation of methanol and carbon monoxide. Mo et al[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. significantly enhanced the methanol oxidation activity of Pt/MnO\u003csub\u003e2\u003c/sub\u003e catalysts by modifying MnO\u003csub\u003e2\u003c/sub\u003e supports with platinum nanoparticles (NPs), compared to pristine MnO\u003csub\u003e2\u003c/sub\u003e. Characterization results revealed that the superior reactivity of Pt/MnO\u003csub\u003e2\u003c/sub\u003e could be attributed to the interfacial interaction between Pt NPs and the MnO\u003csub\u003e2\u003c/sub\u003e support, which modulated the local Pt-Mn coordination environment. It was interaction endowed the catalyst with enhanced low-temperature reducibility, a high concentration of Mn\u003csup\u003e4+\u003c/sup\u003e species, and highly active surface lattice oxygen. Tian et al[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. synthesized platinum-loaded ZSM-5 catalysts for the complete oxidation of CO and C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e6\u003c/sub\u003e. Pt/ZSM-5 catalyst demonstrated strong metal-support interactions between atomically dispersed Pt species and the ZSM-5 framework. The synergistic effects of PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e species and Pt-associated lattice oxygen as active centers enabled Pt/ZSM-5 catalyst to achieve complete oxidation with high reaction rates and low activation energy. Notably, despite the exceptional performance of platinum-loaded catalysts, the high cost of platinum remains a critical limitation for their large-scale production and practical application.\u003c/p\u003e\u003cp\u003eThus, doping Cu/SSZ-13 catalysts with trace platinum had become a reliable alternative strategy to obtain high-performance SCO catalysts. Yu et al[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. designed a Pt/Cu-SSZ-13 catalyst that exhibited excellent NH\u003csub\u003e3\u003c/sub\u003e-SCO performance under realistic conditions with water vapor, achieving 100% conversion at 200\u0026ndash;350\u0026deg;C and over 85% N\u003csub\u003e2\u003c/sub\u003e selectivity across the entire tested temperature range. Liu et al[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. developed a PtCu/SSZ-13 catalyst where PtCu alloy nanoparticles were dispersed on the support surface. In this system, Pt species in the alloyed PtCu nanoparticles existed in an electron-rich state, while electron-deficient Cu and isolated Cu\u003csup\u003e2+\u003c/sup\u003e species coexisted on the PtCu-SSZ-13 surface. It was unique alloy structure with modulated oxidation states significantly improved the N\u003csub\u003e2\u003c/sub\u003e selectivity of NH\u003csub\u003e3\u003c/sub\u003e-SCO over PtCu/SSZ-13 catalyst.\u003c/p\u003e\u003cp\u003eIn this study, we adopted a simple impregnation method utilizing SSZ-13 zeolite as a shared substrate for supporting Pt and Cu. By systematically investigating the effects of impregnation sequence, we elucidated their interaction mechanisms on catalyst performance and the oxidation reaction pathways of CH\u003csub\u003e3\u003c/sub\u003eOH over the catalyst. This work provides crucial guidance for designing high-efficiency CH\u003csub\u003e3\u003c/sub\u003eOH-SCO catalysts with superior activity and minimized byproduct formation.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Catalyst preparation\u003c/h2\u003e\u003cp\u003eCu/SSZ-13 and Pt/SSZ-13 catalysts were prepared by impregnation; Pt-Cu/SSZ-13 (co-impregnated with Cu and Pt) catalysts were prepared by co-impregnation; Pt/Cu/SSZ-13 (prepared by sequential impregnation of Cu followed by Pt) and Cu/Pt/SS-13 (Pt impregnated first, followed by Cu) catalysts were prepared by distribution impregnation. The detailed preparation protocols were described in Supporting Information.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Catalyst activity test\u003c/h2\u003e\u003cp\u003eThe evaluation of the catalytic activity was displayed in Supporting Information.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Catalyst characterization\u003c/h2\u003e\u003cp\u003eThe physical and chemical properties of catalyst samples were characterized with X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDS), N\u003csub\u003e2\u003c/sub\u003e adsorption-desorption, X-ray photoelectron spectra (XPS), Ultraviolet\u0026ndash;Visible Diffuse Reflectance Spectroscopy (UV-Vis/DRS), H\u003csub\u003e2\u003c/sub\u003e temperature programmed reduction (H\u003csub\u003e2\u003c/sub\u003e-TPR) and CO\u003csub\u003e2\u003c/sub\u003e temperature programmed desorption (CO\u003csub\u003e2\u003c/sub\u003e-TPD). The adsorption behavior of gaseous reactants and in-situ CH\u003csub\u003e3\u003c/sub\u003eOH-SCO reaction processes were investigated via In-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (In-situ DRIFTS) to reveal the possible reaction mechanism. The detailed test conditions were described in Supporting Information.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n \u003ch2\u003e3.1 CH\u003csub\u003e3\u003c/sub\u003eOH-SCO performance\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e(a) displays the CH\u003csub\u003e3\u003c/sub\u003eOH conversion of Cu/SSZ-13, Pt/SSZ-13, Pt-Cu/SSZ-13, Pt/Cu/SSZ-13, and Cu/Pt/SSZ-13 catalysts within the temperature range of 100\u0026ndash;300\u0026deg;C. As shown in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e(a), Cu/SSZ-13 catalyst exhibited relatively moderate methanol oxidation performance at low temperatures, with T\u003csub\u003e100\u003c/sub\u003e (the temperature at which 100% CH\u003csub\u003e3\u003c/sub\u003eOH conversion was achieved) of 220\u0026deg;C. The catalytic activity improved for Pt/Cu/SSZ-13 catalyst, which T\u003csub\u003e100\u003c/sub\u003e was reduced to 200\u0026deg;C. It further confirmed that Pt modification enhanced the catalytic activity of Cu/SSZ-13. After changing the impregnation order, Pt-Cu/SSZ-13 catalyst demonstrated a notably higher performance, with T\u003csub\u003e100\u003c/sub\u003e of 180\u0026deg;C. Further optimization of impregnation sequence, Cu/Pt/SSZ-13 catalyst resulted in a remarkable improvement, reaching 100% CH\u003csub\u003e3\u003c/sub\u003eOH conversion even at a low temperature of 160\u0026deg;C. These findings highlight that the impregnation sequence of Pt and Cu significantly influenced the SCO performance of PtCu/SSZ-13 catalysts. Surprisingly, Pt/SSZ-13 catalyst demonstrated exceptional methanol oxidation performance, maintaining 100% CH\u003csub\u003e3\u003c/sub\u003eOH conversion across the entire temperature range of 100\u0026ndash;300\u0026deg;C. This superior activity was attributed to the exceptionally strong oxidative capacity of Pt species, which enabled complete low-temperature oxidation of CH\u003csub\u003e3\u003c/sub\u003eOH[\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e(b) shows the HCHO yields of the five catalysts within the temperature range of 100\u0026ndash;300\u0026deg;C. The results indicated that all five catalysts generated small amounts of HCHO byproducts at low temperatures. The HCHO yield order at low temperatures was determined as Pt/Cu/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Cu/Pt/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Cu/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Pt-Cu/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Pt/SSZ-13. Figure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e(c) shows the CO yields of the five catalysts within the temperature range of 100\u0026ndash;300\u0026deg;C. The results indicated that Cu/SSZ-13 catalyst generated the highest CO yield (4.3%) across the entire temperature window, followed by Pt/Cu/SSZ-13 catalyst with a yield of 2.5%. In contrast, virtually no CO production was detected for Pt/SSZ-13, Pt-Cu/SSZ-13, and Cu/Pt/SSZ-13 catalysts throughout the tested temperature range.\u003c/p\u003e\n \u003cp\u003eThe methanol/diesel dual-fuel engine operates in two modes: (1) Diesel mode: Pure diesel was utilized as the sole fuel, analogous to conventional diesel engines. The exhaust characteristics remained consistent with traditional diesel emissions, necessitating aftertreatment systems such as SCR or EGR (Exhaust Gas Recirculation) to comply with Tier III emission standards. (2) Methanol-dominant mode: Methanol served as the primary fuel (accounting for over 90% of consumption), with diesel acting as the ignition fuel[\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e]. In this mode, the exhaust contained both NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e and unburned methanol, which exhibited distinct emission profiles compared to conventional diesel engines. While conventional SCR/EGR systems effectively reduced NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e emissions, the residual methanol required specialized SCO aftertreatment[\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e]. To address the emission control demands of marine methanol-fueled engines, we hoped that the developed catalysts were based on realizing efficient SCO removal of methanol and also possessing SCR denitrification functions., thus reducing the complexity and cost of after-treatment systems. Consequently, we further investigated the performance of this series of catalysts for the synergistic catalytic removal of methanol and NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e.\u003c/p\u003e\n \u003cp\u003eThe simultaneous NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e reduction and CH\u003csub\u003e3\u003c/sub\u003eOH oxidation performance of the five catalysts was evaluated under co-feeding conditions of 500 ppm CH\u003csub\u003e3\u003c/sub\u003eOH, 500 ppm NH\u003csub\u003e3\u003c/sub\u003e, 500 ppm NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e, 5% O\u003csub\u003e2\u003c/sub\u003e, and balanced N\u003csub\u003e2\u003c/sub\u003e within the temperature range of 100\u0026ndash;450\u0026deg;C. As shown in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e(a), all Cu-containing catalysts (Cu/SSZ-13, Pt-Cu/SSZ-13, Pt/Cu/SSZ-13, and Cu/Pt/SSZ-13) exhibited nearly identical methanol removal performance, with T\u003csub\u003e100\u003c/sub\u003e of 225\u0026deg;C. In contrast, Pt/SSZ-13 catalyst demonstrated significantly weaker CH\u003csub\u003e3\u003c/sub\u003eOH oxidation activity, with its T\u003csub\u003e100\u003c/sub\u003e increasing to 250\u0026deg;C. Notably, compared to its standalone CH\u003csub\u003e3\u003c/sub\u003eOH-SCO performance, Pt/SSZ-13 catalyst showed a marked decline in methanol conversion efficiency under simultaneous NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e reduction and CH\u003csub\u003e3\u003c/sub\u003eOH oxidation conditions. It could be attributed to competitive adsorption between NH\u003csub\u003e3\u003c/sub\u003e and CH\u003csub\u003e3\u003c/sub\u003eOH on the catalyst surface, which likely suppressed CH\u003csub\u003e3\u003c/sub\u003eOH activation and oxidation over Pt/SSZ-13. Figure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e(b) showed the HCHO yields of the five catalysts within the temperature range of 100\u0026ndash;450\u0026deg;C. All Pt-containing catalysts (Pt/SSZ-13, Pt-Cu/SSZ-13, Pt/Cu/SSZ-13, and Cu/Pt/SSZ-13) generated minimal HCHO (\u0026lt;\u0026thinsp;5 ppm) only at low temperatures (100\u0026ndash;150\u0026deg;C). In contrast, Cu/SSZ-13 catalyst exhibited nearly 100% HCHO yield in the 100\u0026ndash;200\u0026deg;C range, indicating that CH\u003csub\u003e3\u003c/sub\u003eOH was predominantly oxidized to HCHO at low temperatures over this catalyst. Figure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e(c) displayed the CO yields of the five catalysts across the same temperature range. All catalysts produced negligible CO (\u0026lt;\u0026thinsp;5 ppm) only between 200\u0026ndash;250\u0026deg;C. The results demonstrate that under simultaneous NH\u003csub\u003e3\u003c/sub\u003e, NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e, and CH\u003csub\u003e3\u003c/sub\u003eOH co-feeding conditions, Pt-Cu/SSZ-13, Pt/Cu/SSZ-13, and Cu/Pt/SSZ-13 catalysts exhibited superior SCO performance.\u003c/p\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e(d) showed the NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e conversion efficiencies of the five catalysts within the temperature range of 100\u0026ndash;450\u0026deg;C. Cu/SSZ-13 catalyst exhibited 100% across a broad temperature window of 185\u0026ndash;329\u0026deg;C. After modifying Cu/SSZ-13 with Pt via impregnation to form Pt/Cu/SSZ-13, the denitration performance slightly declined, achieving\u0026thinsp;~\u0026thinsp;100% NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e conversion within a window of 194\u0026ndash;316\u0026deg;C. Modifying the impregnation sequence, both Pt-Cu/SSZ-13 and Cu/Pt/SSZ-13 catalysts showed a low-temperature shift in their active windows, with nearly identical NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e conversion profiles (~\u0026thinsp;100% within 191\u0026ndash;314\u0026deg;C). In contrast, Pt/SSZ-13 catalyst demonstrated a much narrower active window (246\u0026ndash;279\u0026deg;C). Figure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e(e) presented the N\u003csub\u003e2\u003c/sub\u003e selectivity of the five catalysts over the same temperature range. The N\u003csub\u003e2\u003c/sub\u003e selectivity trends mirrored the NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e conversion performance, following the order: Cu/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Pt/Cu/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Cu/Pt/SSZ-13\u0026thinsp;\u0026asymp;\u0026thinsp;Pt-Cu/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Pt/SSZ-13. Notably, the Pt/SSZ-13 catalyst exhibited anomalously low N\u003csub\u003e2\u003c/sub\u003e selectivity (-17%), which was attributed to the over-oxidation of NH\u003csub\u003e3\u003c/sub\u003e to N\u003csub\u003e2\u003c/sub\u003eO by highly oxidative Pt species, resulting in negative selectivity[\u003cspan class=\"CitationRef\"\u003e19\u003c/span\u003e]. These results confirmed that Cu-containing catalysts demonstrated superior SCR performance under simultaneous NH\u003csub\u003e3\u003c/sub\u003e, NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e, and CH\u003csub\u003e3\u003c/sub\u003eOH co-feeding conditions, achieving both high NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e conversion efficiency and favorable N\u003csub\u003e2\u003c/sub\u003e selectivity.\u003c/p\u003e\n \u003cp\u003eBased on the results of CH\u003csub\u003e3\u003c/sub\u003eOH-SCO and simultaneous NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e-Methanol removal, Cu/Pt/SSZ-13 catalyst prepared through sequential impregnation demonstrated dual functionality: (1) exhibited excellent selective catalytic oxidation (SCO) activity at low temperatures, maintaining a CH\u003csub\u003e3\u003c/sub\u003eOH conversion rate exceeding 100% across a broad temperature window of 150\u0026ndash;300\u0026deg;C; (2) displayed satisfactory SCR performance. Therefore, Cu/Pt/SSZ-13 catalyst will be selected in the following as the main study for subsequent CH\u003csub\u003e3\u003c/sub\u003eOH-SCO characterization and analysis. Notably, while the Pt/SSZ-13 catalyst showed superior CH\u003csub\u003e3\u003c/sub\u003eOH-SCO activity, its practical application in methanol/diesel dual-fuel engines remained unsuitable due to insufficient SCR performance. Consequently, Pt/SSZ-13 served solely as a control catalyst in this study to elucidate the mechanistic impacts of impregnation sequence on Pt-modified Cu/SSZ-13 catalysts during SCO processes.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003e3.2 Structural and textural characteristics\u003c/h2\u003e\n \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e\n \u003ch2\u003e3.2.1 XRD\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e shows the XRD characterization results of the synthesized catalysts. Clear diffraction peaks corresponding to the chabazite (CHA) structure of SSZ-13 zeolite were clearly observed for all catalysts, indicating that neither the stepwise nor co-impregnation methods, nor the incorporation of transition or noble metals, disrupted the zeolitic framework[\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e]. It confirmed the strong structural stability of SSZ-13 zeolite. High-resolution magnification was performed on regions associated with CuO and Pt species. A weak diffraction peak at 38.7 \u0026deg; was detected in all Cu-containing catalysts, which was attributed to CuO species, suggesting the formation of small-sized CuO crystallites on their surfaces[\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]. Similarly, diffraction peaks related to the Pt (111) plane were observed in all Pt-containing catalysts, but with very low intensity. It could be attributed to the low Pt loading or the uniform distribution of Pt species without significant aggregation[\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e\n \u003ch2\u003e3.2.2 TEM and EDS\u003c/h2\u003e\n \u003cp\u003eTEM and EDS images of Cu/SSZ-13 (a), Pt/SSZ-13 (b), Pt-Cu/SSZ-13 (c), Pt/Cu/SSZ-13 (d), and Cu/Pt/SSZ-13 (e) catalysts are shown in Figs. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e and \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e, respectively. CuO clusters smaller than 2 nm were uniformly distributed on the surface of Cu/SSZ-13 catalyst and the Cu elements were well dispersed[\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e]. For Pt/SSZ-13 catalysts, metallic Pt and PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e species with a lattice spacing of about 0.2 nm were observed on the surface. It indicated that in the Pt-containing catalysts (Pt/SSZ-13, Pt-Cu/SSZ-13, Pt/Cu/SSZ-13, Cu/Pt/SSZ-13), Pt mainly existed as metallic Pt and PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e on the surface of the carriers or at the entrance of the zeolite pores. In addition, EDS results further verified the high dispersion of Pt species[\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e]. For Pt-Cu/SSZ-13 catalyst, some agglomerates due to uneven metal distribution were observed on the surface, which was related to the simultaneous competition of Pt and Cu precursors for the adsorption sites of the carrier. It was hypothesized by EDS mapping that the agglomerates might be the oxide species of Pt and Cu in the form of massive clusters. Pt/Cu/SSZ-13 catalyst boundaries showed a large number of species with inhomogeneous sizes, which may be mainly Pt-CuO composites formed by Pt species in amorphous state and a small number of CuO clusters[\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e]. It suggested that the preferential impregnation of Cu with higher loading blocked the microporous entrances or internal channels, which led to the ineffective dispersion of the subsequent Pt impregnation, thus further aggravating the pore blockage. When Cu/Pt/SSZ-13 catalyst was impregnated with Pt first, its precursors preferentially occupied the high-affinity sites on the surface of the SSZ-13 carrier, which provided nucleation centers for the subsequently impregnated Cu and inhibited the aggregation of Cu particles. It was noteworthy that the outer surface of Cu/Pt/SSZ-13 catalyst showed large particles in the form of clumps, which could be hypothesized to be the clumps formed by PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e and CuO species in combination with the EDS patterns. It was due to the excessive Cu loading, some Cu elements aggregated on the outer surface of the zeolite, the formation of massive CuO species after high temperature calcination, and the formation of Pt-Cu nanocrystals from some Pt species on the surface of SSZ-13 and massive CuO during the process of secondary impregnation. However, such Pt-Cu nanoclusters were mainly embedded in the outer surface of the catalyst and had minimal effect on the active sites on the surface or inside the catalyst zeolite[\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e\n \u003ch2\u003e3.2.3 BET\u003c/h2\u003e\n \u003cp\u003eThe surface physical properties of the synthesized catalysts were investigated via N\u003csub\u003e2\u003c/sub\u003e adsorption-desorption experiments, with the results shown in Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e. All catalysts exhibited Type I isotherms, characteristic of microporous materials[\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e]. Table. 1 summarizes the specific surface areas, micropore areas, average pore diameter, and pore volumes of the catalysts. The order of specific surface area and microporous area size was Pt/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Cu/Pt/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Pt/Cu/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Pt-Cu/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Cu/SSZ-13, and the pore volume and pore diameter were in the following order: Cu/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Cu/Pt/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Pt-Cu/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Pt/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Pt/Cu/SSZ-13. Pt/SSZ-13 catalyst exhibited a high specific surface area (566.5 m\u003csup\u003e2\u003c/sup\u003e/g), suggesting that low-loading Pt was dispersed on the support surface via strong interactions with active sites (Si-O-Al\u003csup\u003e\u0026minus;\u003c/sup\u003e)[\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e]. Cu/SSZ-13 catalyst displayed a lower specific surface area and micropore area due to severe Cu aggregation and pore blockage at high Cu loadings. For Pt/Cu/SSZ-13 catalyst, the high Cu loading nearly completely blocked the micropores, and subsequently impregnated Pt primarily existed in an oxidized state (PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e) on the catalyst surface. It indicated that PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e species could promote Cu dispersion, thereby alleviating micropore blockage. Consequently, the specific surface area and micropore area of Pt/Cu/SSZ-13 catalyst increased compared to Cu/SSZ-13. When the impregnation sequence was altered (Pt-Cu/SSZ-13, co-impregnation), the specific surface area and micropore area slightly decreased relative to Pt/Cu/SSZ-13, implying that competitive adsorption between Pt and Cu precursors during co-impregnation weakened Pt\u0026rsquo;s inhibitory effect on Cu aggregation[\u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e]. Optimizing the impregnation sequence, the specific surface area, pore volume and pore size of Cu/Pt/SSZ-13 catalysts impregnated with Pt first and Cu later were significantly enhanced. This improvement was attributed to the preferential dispersion of PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e species on the support surface during the initial impregnation step, forming highly dispersed nanoparticles. Subsequently deposited CuO clusters covered the Pt species, while the strong anchoring effect of Pt suppressed Cu agglomeration, reducing metal particle size and mitigating micropore blockage[\u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eIn summary, among Pt-modified Cu/SSZ-13 catalysts with different impregnation sequences, the adoption of the order of preferential impregnation of Pt followed by Cu impregnation could result in Cu/Pt/SSZ-13 catalyst having larger pore diameters, higher specific surface areas and microporous areas at the same time, which could expose more active sites and exhibit excellent adsorption and catalytic abilities.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eBET surface area and pore structure results of prepared catalysts.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCatalysts\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eS\u003csub\u003eBET\u003c/sub\u003e (m\u003csup\u003e2\u003c/sup\u003e/g)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMicropore Area (m\u003csup\u003e2\u003c/sup\u003e/g)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eAverage pore Diameter (nm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePore Volume (cm\u003csup\u003e3\u003c/sup\u003e/g)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCu/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e461.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e434.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.578\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.228\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e566.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e539.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.290\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.042\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt-Cu/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e475.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e449.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.375\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.045\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt/Cu/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e488.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e459.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.283\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.038\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCu/Pt/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e516.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e505.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.508\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.068\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e\n \u003ch2\u003e3.2.4 UV-Vis/DRS\u003c/h2\u003e\n \u003cp\u003eUV-vis/DRS analysis of the prepared catalysts was carried out to investigate the chemical state of catalyst surface ions and the results were shown in Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e. For Cu-containing catalysts, the two peaks observed in the wavelength range of 200\u0026ndash;300 nm were likely associated with charge transfer from stable Cu\u003csup\u003e+\u003c/sup\u003e and isolated Cu\u003csup\u003e2+\u003c/sup\u003e ions to O\u003csup\u003e2\u0026minus;\u003c/sup\u003e, suggesting partial incorporation of Cu\u003csup\u003e+\u003c/sup\u003e and Cu\u003csup\u003e2+\u003c/sup\u003e ions within the SSZ-13 zeolite framework[\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e]. The broad band at 600\u0026ndash;800 nm corresponded to the d-d orbital transition of Cu\u003csup\u003e2+\u003c/sup\u003e ions induced by CuO species[\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e]. In the case of Pt-containing catalysts, the peak appearing between 300\u0026ndash;350 nm was attributed to charge transfer in PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e species[\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e]. Among the five investigated samples, Cu/Pt/SSZ-13 exhibited significantly higher intensities for all five characteristic signals compared to other catalysts, indicating substantial coexistence of PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e, Cu\u003csup\u003e+\u003c/sup\u003e, Cu\u003csup\u003e2+\u003c/sup\u003e, and CuO species when adopting the sequential impregnation of Pt followed by Cu. It was observation suggested that the synergistic interaction between Pt and Cu species played a critical role in enhancing SCO performance of various Pt-modified Cu/SSZ-13 catalysts.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e\n \u003ch2\u003e3.2.4 XPS\u003c/h2\u003e\n \u003cp\u003eTo investigate the surface elemental valence states of Pt-modified Cu/SSZ-13 catalysts with different impregnation sequences, XPS analysis was conducted on the synthesized catalysts, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e. The surface relative contents of Cu and O elements were determined through integral calculations of their characteristic peaks, with results summarized in Table. 2.\u003c/p\u003e\n \u003cp\u003eAs shown in Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e(a), the Pt \u003cem\u003e4d\u003c/em\u003e spectra of Pt-containing catalysts were deconvoluted into two sub-peaks. The higher binding energy peak at ~\u0026thinsp;333 eV was assigned to oxidized Pt species (Pt\u003csup\u003e2+\u003c/sup\u003e or PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e)[\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e]. For Pt/SSZ-13, PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e species exhibited a highly dispersed state, resulting in an elevated binding energy of 333.59 eV. Pt/Cu/SSZ-13 catalyst displayed the lowest binding energy, implying electron enrichment at Pt sites induced by preferential Cu loading, where Cu likely acted as an electron donor to reduce the oxidation state of Pt[\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e]. Pt-Cu/SSZ-13 led to a higher binding energy, which might correlate with metal agglomeration. Competition between Pt and Cu precursors for active sites during impregnation promoted particle growth, thereby decreasing the d-orbital electron density of Pt[\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e]. For the optimized Cu/Pt/SSZ-13 catalyst, the binding energy was intermediate between Pt/SSZ-13 and Pt/Cu/SSZ-13, suggested that subsequent Cu overlayers only partially modified the electronic structure of pre-loaded Pt. This Cu overlayer likely optimized the adsorption strength of SCO reaction intermediates (e.g., formaldehyde, formic acid) by tuning the d-band center of Pt, thereby enhancing catalytic selectivity[\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e]. Notably, all Pt-containing catalysts exhibited a lower binding energy peak at ~\u0026thinsp;316 eV, corresponding to metallic Pt\u003csup\u003e0\u003c/sup\u003e, indicating partial reduction during calcination or pretreatment. The minor binding energy shifts (\u0026Delta;BE\u0026thinsp;\u0026lt;\u0026thinsp;0.8 eV) among Pt\u003csup\u003e0\u003c/sup\u003e signals implied weak Pt-Cu interactions dominated by physical coexistence or subtle electronic effects rather than strong alloying[\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eAs shown in Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e(b), the Cu \u003cem\u003e2p\u003c/em\u003e spectra of Cu-containing catalysts showed peaks at ~\u0026thinsp;935.3 eV and 955.8 eV with satellite features, characteristic of surface Cu\u003csup\u003e2+\u003c/sup\u003e species (CuO). Peaks at ~\u0026thinsp;933.9 eV and 953.5 eV were attributed to Cu\u003csup\u003e0\u003c/sup\u003e and Cu\u003csup\u003e+\u003c/sup\u003e[\u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e]. In Pt-Cu/SSZ-13, competition between Pt and Cu precursors for active sites favored CuO formation (64.4% Cu\u003csup\u003e2+\u003c/sup\u003e). For Pt/Cu/SSZ-13, pre-loaded Cu occupied high-affinity sites in SSZ-13, forcing subsequent Pt deposition onto suboptimal external sites and generating partially reduced Cu species (Cu\u003csup\u003e0\u003c/sup\u003e clusters), which decreased the Cu\u003csup\u003e2+\u003c/sup\u003e proportion to 61.7%. The strong anchoring effect of Pt in Cu/Pt/SSZ-13 stabilized Cu\u003csup\u003e+\u003c/sup\u003e species (Cu\u003csub\u003e2\u003c/sub\u003eO) via electronic interactions, yielding the lowest Cu\u003csup\u003e2+\u003c/sup\u003e content (56.2%).\u003c/p\u003e\n \u003cp\u003eThe surface oxygen species significantly influenced the redox properties of the catalysts. Figure \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e(c) displayed the O \u003cem\u003e1s\u003c/em\u003e XPS spectra of the five catalysts. Through spectral deconvolution, two distinct oxygen species were identified on the catalyst surfaces: the higher binding energy peak corresponded to chemisorbed oxygen species (O\u003csup\u003e2\u0026minus;\u003c/sup\u003e or O\u003csup\u003e\u0026minus;\u003c/sup\u003e, denoted as O\u003csub\u003e\u003cem\u003eads\u003c/em\u003e\u003c/sub\u003e), while the lower binding energy peak was attributed to lattice oxygen (O\u003csup\u003e2\u0026minus;\u003c/sup\u003e, denoted as O\u003csub\u003e\u003cem\u003elatt\u003c/em\u003e\u003c/sub\u003e). O\u003csub\u003e\u003cem\u003eads\u003c/em\u003e\u003c/sub\u003e participated more readily in redox reactions compared to O\u003csub\u003e\u003cem\u003elatt\u003c/em\u003e\u003c/sub\u003e, which remained tightly bound within the zeolite framework[\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e]. Consequently, a higher O\u003csub\u003e\u003cem\u003eads\u003c/em\u003e\u003c/sub\u003e / (O\u003csub\u003e\u003cem\u003eads\u003c/em\u003e\u003c/sub\u003e + O\u003csub\u003e\u003cem\u003elatt\u003c/em\u003e\u003c/sub\u003e) ratio correlated with enhanced redox activity. As summarized in Table. 2, among the three Pt-modified Cu/SSZ-13 catalysts prepared with different impregnation sequences, Cu/Pt/SSZ-13 exhibited the highest surface-adsorbed oxygen ratio (91.4%). It could be attributed to PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e anchoring at high-energy surface sites, which enhanced oxygen mobility, reduced oxygen vacancy formation energy, and facilitated oxygen activation, collectively improving redox capability[\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e42\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eTable. 2.\u003c/strong\u003e XPS data of all catalysts.\u003c/p\u003e\n \u003cp\u003e\u003cimg 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\"\u003e\u003c/p\u003e\n \u003cdiv align=\"center\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\u003c/table\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\n \u003ch2\u003e3.3 Redox properties\u003c/h2\u003e\n \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e\n \u003ch2\u003e3.3.1 O\u003csub\u003e2\u003c/sub\u003e-TPD\u003c/h2\u003e\n \u003cp\u003eO\u003csub\u003e2\u003c/sub\u003e-TPD analysis was conducted to investigate oxygen species in the five catalysts, with results shown in Fig. \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e. The O\u003csub\u003e2\u003c/sub\u003e desorption peaks in the 200\u0026ndash;500\u0026deg;C range were attributed to O\u003csub\u003e\u003cem\u003eads\u003c/em\u003e\u003c/sub\u003e, while those in the 500\u0026ndash;900\u0026deg;C range corresponded to O\u003csub\u003e\u003cem\u003elatt\u003c/em\u003e\u003c/sub\u003e. All catalysts exhibited significantly higher intensity for surface-adsorbed oxygen than lattice oxygen. Previous studies reported that adsorbed oxygen species (e.g., O\u003csup\u003e\u0026minus;\u003c/sup\u003e, O\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e) directly interact with methanol or its intermediates (e.g., CO*, HCOO\u003csup\u003e\u0026minus;\u003c/sup\u003e), facilitating C-H bond cleavage and complete oxidation to CO\u003csub\u003e2\u003c/sub\u003e, suggesting the dominant role of adsorbed oxygen in methanol catalytic oxidation[\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe desorption peaks of O\u003csub\u003e\u003cem\u003eads\u003c/em\u003e\u003c/sub\u003e shifted to lower-temperature regions in the order: Pt/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Pt-Cu/SSZ-13\u0026thinsp;\u0026asymp;\u0026thinsp;Pt/Cu/SSZ-13\u0026thinsp;\u0026asymp;\u0026thinsp;Cu/Pt/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Cu/SSZ-13, indicating faster reaction kinetics of adsorbed oxygen on Pt-containing catalysts. Furthermore, although Pt-modified Cu/SSZ-13 catalysts with different impregnation sequences showed nearly identical peak positions for adsorbed oxygen, their relative abundance (calculated via curve integration) ranked in descending order: Cu/Pt/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Pt-Cu/SSZ-13\u0026thinsp;\u0026gt;\u0026thinsp;Pt/Cu /SSZ-13. The sequential impregnation strategy optimized both oxygen mobility and active site distribution, explaining the superior SCO performance of Cu/Pt/SSZ-13 observed in catalytic testing. These observations aligned with XPS results.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec16\" class=\"Section3\"\u003e\n \u003ch2\u003e3.3.1 H\u003csub\u003e2\u003c/sub\u003e-TPR\u003c/h2\u003e\n \u003cp\u003eThe redox properties of the five catalysts were investigated via H\u003csub\u003e2\u003c/sub\u003e-TPR experiments, with the results shown in Fig. \u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e and Table. 3. For Pt/SSZ-13 catalyst, two weak peaks were observed: the first peak was attributed to the reduction of minor isolated Pt\u003csup\u003e2+\u003c/sup\u003e ions exchanged within zeolite channels; the second peak corresponded to the reduction of PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e species to metallic Pt\u003csup\u003e0\u003c/sup\u003e, which likely resided on the zeolite surface or near 6-membered ring (6-MR) pore entrances[\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e]. In Cu/SSZ-13, Pt/Cu/SSZ-13, Cu/Pt/SSZ-13, and Pt-Cu/SSZ-13 catalysts, four distinct reduction peaks were identified: Peak 1: Reduction of isolated Cu\u003csup\u003e2+\u003c/sup\u003e ions near 8-membered ring (8-MR) windows and within CHA cages. Peak 2: Single-step reduction of CuO clusters to metallic Cu\u003csup\u003e0\u003c/sup\u003e. Peak 3: Reduction of Cu\u003csup\u003e2+\u003c/sup\u003e species localized near or at 6-MR pore entrances[\u003cspan class=\"CitationRef\"\u003e44\u003c/span\u003e]. Peak 4: reduction of minor PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e species to metallic Pt\u003csup\u003e0\u003c/sup\u003e.\u003c/p\u003e\n \u003cp\u003eIntriguingly, the total H\u003csub\u003e2\u003c/sub\u003e consumption of Pt/SSZ-13 and Cu/SSZ-13 catalysts showed an inverse correlation with their CH\u003csub\u003e3\u003c/sub\u003eOH-SCO activities, suggesting that total reducibility alone was not the decisive factor for methanol oxidation performance[\u003cspan class=\"CitationRef\"\u003e45\u003c/span\u003e]. Notably, Cu/Pt/SSZ-13 catalyst showed significantly stronger H\u003csub\u003e2\u003c/sub\u003e consumption for the reduction peaks corresponding to CuO and PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e compared to Pt/Cu/SSZ-13 and Pt-Cu/SSZ-13. It was observation indicated enhanced synergistic catalytic oxidation of methanol by CuO and PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e species in Cu/Pt/SSZ-13. The optimized synergy accounted for the superior CH\u003csub\u003e3\u003c/sub\u003eOH-SCO performance of Cu/Pt/SSZ-13, where Pt\u003csup\u003e2+\u003c/sup\u003e facilitated the activation of CuO, while CuO stabilized Pt in an oxidized state critical for methanol C-H bond cleavage. The sequential Pt-then-Cu impregnation strategy enabled spatial and electronic coupling between Pt and Cu species, establishing a hierarchically structured active site system that maximized oxygen migration efficiency during catalytic cycles. These findings revealed that PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e-CuO interfacial interaction served as the key driving force for complete methanol oxidation.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003e-TPR data of Cu\u003csub\u003e2.5\u003c/sub\u003e/SSZ-13, Cu\u003csub\u003e10\u003c/sub\u003e/SSZ-13 and Cu\u003csub\u003e12.5\u003c/sub\u003e/SSZ-13 catalysts\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eSamples\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"9\"\u003e\n \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003e consumption (mmol / g)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePeak 1\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003ePeak 2\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003ePeak 3\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003ePeak 4\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCu/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e2.56\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.84\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt-Cu/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e2.14\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt/Cu/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e1.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCu/Pt/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e2.27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\n \u003ch2\u003e3.4 Surface acidity\u003c/h2\u003e\n \u003cdiv id=\"Sec18\" class=\"Section3\"\u003e\n \u003ch2\u003e3.4.1 CO\u003csub\u003e2\u003c/sub\u003e-TPD\u003c/h2\u003e\n \u003cp\u003eThe surface basicity of the synthesized catalysts was investigated via CO\u003csub\u003e2\u003c/sub\u003e-TPD experiments to evaluate the effects of impregnation sequences on Pt-modified Cu/SSZ-13 catalysts, with results shown in Fig. \u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003e. The quantitative analysis of the total alkalinity on the catalyst surface was calculated from the integration of the CO\u003csub\u003e2\u003c/sub\u003e-TPD curve and the results are listed in Table \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e. All catalysts exhibited desorption peaks in the 100\u0026ndash;350\u0026deg;C and 350\u0026ndash;600\u0026deg;C temperature ranges. Based on prior reports, the low-temperature peak (\u0026lt;\u0026thinsp;350\u0026deg;C) was attributed to weak basic sites corresponding to CO\u003csub\u003e2\u003c/sub\u003e desorption from hydrated hydroxyl groups. The CO\u003csub\u003e2\u003c/sub\u003e desorption peaks above 350\u0026deg;C were attributed to strongly basic sites, corresponding to the desorption of CO\u003csub\u003e2\u003c/sub\u003e adsorbed on the free hydroxyl groups on the catalyst surface[\u003cspan class=\"CitationRef\"\u003e46\u003c/span\u003e]. Monometallic Pt/SSZ-13 and Cu/SSZ-13 catalysts primarily displayed weak basicity. In contrast, bimetallic catalysts showed enhanced peaks for strong basic sites but significantly reduced total basicity compared to monometallic counterparts, suggesting competitive or synergistic interactions between Pt and Cu species that altered hydroxyl group distributions. Notably, Pt-modified Cu/SSZ-13 catalysts with different impregnation sequences exhibited comparable total basicity. Among them, Cu/Pt/SSZ-13 catalyst demonstrated the highest concentration of strong basic sites (0.3 mmol/g). This increased population of strong basic sites likely facilitated methanol activation via C-H bond polarization, thereby enhancing SCO performance[\u003cspan class=\"CitationRef\"\u003e47\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e48\u003c/span\u003e]. The sequential Pt-then-Cu strategy optimized the balance between acidic and basic sites, favoring the formation of stable reaction intermediates during CH\u003csub\u003e3\u003c/sub\u003eOH oxidation.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eCO\u003csub\u003e2\u003c/sub\u003e-TPD results of all catalysts.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eCatalysts\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eAcid amount (mmol/g)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eTotal acidity\u003c/p\u003e\n \u003cp\u003e(mmol/g)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePeak Ⅰ\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePeak Ⅱ\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCu/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.84\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.49\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt-Cu/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePt/Cu/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCu/Pt/SSZ-13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e\n \u003ch2\u003e3.5. Experimental In-situ DRIFTS\u003c/h2\u003e\n \u003cdiv id=\"Sec20\" class=\"Section3\"\u003e\n \u003ch2\u003e3.5.1 Catalyst preparation Adsorption of CH\u003csub\u003e3\u003c/sub\u003eOH\u0026thinsp;+\u0026thinsp;O\u003csub\u003e2\u003c/sub\u003e\u003c/h2\u003e\n \u003cp\u003eIn-situ DRIFTS experiments of CH\u003csub\u003e3\u003c/sub\u003eOH\u0026thinsp;+\u0026thinsp;O\u003csub\u003e2\u003c/sub\u003e co-adsorption on Cu/Pt/SSZ-13 catalyst was conducted to investigate the types of methanol-derived species adsorbed on the catalyst surface at different temperatures, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e12\u003c/span\u003e. A negative peak at 3668 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e corresponded to the O-H stretching vibration of surface hydroxyl groups[\u003cspan class=\"CitationRef\"\u003e49\u003c/span\u003e]. Characteristic peaks near 2959 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 2846 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were attributed to C-H stretching vibrations of methanol and methoxy (CH\u003csub\u003e3\u003c/sub\u003eO\u003csup\u003e\u0026minus;\u003c/sup\u003e) species, respectively[\u003cspan class=\"CitationRef\"\u003e50\u003c/span\u003e]. The peak at 2154 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e aligned with gaseous CO\u003csub\u003e2\u003c/sub\u003e formation, while the feature at 2129 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e originated from adsorbed CO[\u003cspan class=\"CitationRef\"\u003e51\u003c/span\u003e]. Peaks at 1678 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1655 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were assigned to C\u0026thinsp;=\u0026thinsp;O stretching vibrations of aldehyde (-CHO) and formic acid (HCOOH) species, respectively[\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e]. The diminishing intensity of formic acid-related peaks suggested rapid decomposition of formate intermediates or direct oxidation of formaldehyde to CO\u003csub\u003e2\u003c/sub\u003e, bypassing intermediate stages. The peak near 1585 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e arose from asymmetric O-C-O stretching of carboxylate (COO\u003csup\u003e\u0026minus;\u003c/sup\u003e) species, while the feature at 1470 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e corresponded to symmetric O-C-O stretching of formate (HCOO\u003csup\u003e\u0026minus;\u003c/sup\u003e) intermediates, both critical in methanol oxidation pathways[\u003cspan class=\"CitationRef\"\u003e53\u003c/span\u003e]. The emergence of a carbonate (CO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e) peak at 1509 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 200\u0026deg;C indicated deep oxidation of methanol[\u003cspan class=\"CitationRef\"\u003e53\u003c/span\u003e]. A prominent peak at 1295 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e represented C-O stretching of methanol, while features near 1250 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1120 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were linked to C-O vibrations of methoxy (CH\u003csub\u003e3\u003c/sub\u003eO\u003csup\u003e\u0026minus;\u003c/sup\u003e) species[\u003cspan class=\"CitationRef\"\u003e54\u003c/span\u003e]. The progressive enhancement of CH\u003csub\u003e3\u003c/sub\u003eO\u003csup\u003e\u0026minus;\u003c/sup\u003e-related peaks across 50\u0026ndash;350\u0026deg;C demonstrated the persistent involvement of methoxy species throughout the SCO reaction. This observation implied that Pt doping facilitated direct dehydrogenation of methanol to methoxy species, rather than relying on surface hydroxyl groups or oxygen vacancies. Such a pathway shortened the reaction route, enabling rapid methanol removal at low temperatures.\u003c/p\u003e\n \u003cp\u003eIn-situ DRIFTS experiments were conducted to investigate the transient CH\u003csub\u003e3\u003c/sub\u003eOH-SCO reaction of co-adsorbed CH\u003csub\u003e3\u003c/sub\u003eOH and O\u003csub\u003e2\u003c/sub\u003e on the Cu/Pt/SSZ-13 catalyst at 200\u0026deg;C, with results shown in Fig. \u003cspan class=\"InternalRef\"\u003e13\u003c/span\u003e. As shown in Fig. \u003cspan class=\"InternalRef\"\u003e13\u003c/span\u003e(b), the peak intensities attributed to methanol species in the in-situ spectra of Pt/Cu/SSZ-13 catalyst gradually increased with reaction time (1\u0026ndash;60 min), indicating that the catalyst continued to adsorb methanol at 200\u0026deg;C, which implied insufficient adsorption functionality. From Fig. \u003cspan class=\"InternalRef\"\u003e13\u003c/span\u003e, the peaks corresponding to methoxy and formate species progressively intensified for all three catalysts as the reaction time increased, further confirming that methoxy and formate were key intermediates in the CH₃OH-SCO reaction.\u003c/p\u003e\n \u003cp\u003eNotably, Cu/Pt/SSZ-13 catalyst exhibited weaker formate-related peaks, suggesting that it partially bypassed the formate generation stage, thereby suppressing formic acid accumulation and directly promoting complete methanol oxidation to CO\u003csub\u003e2\u003c/sub\u003e. The rapid enrichment of methoxy and formate species indicated that the reaction pathway predominantly followed a direct dehydrogenation-oxidation mechanism, rather than sequential carboxylate-mediated steps. It was behavior aligned with the catalyst\u0026rsquo;s high low-temperature SCO efficiency, as suppressing formate accumulation minimized intermediate poisoning and accelerated overall reaction kinetics. The Pt-first impregnation sequence enhanced the synergy between Pt (facilitating C-H bond cleavage) and CuO (enhancing oxygen mobility), thereby enabling this simplified reaction pathway[\u003cspan class=\"CitationRef\"\u003e55\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e56\u003c/span\u003e].\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec21\" class=\"Section3\"\u003e\n \u003ch2\u003e3.5.2 Discussion on reaction mechanism\u003c/h2\u003e\n \u003cp\u003eProposed Methanol Catalytic Oxidation Pathway (Based on In Situ DRIFTS)\u003c/p\u003e\n \u003cp\u003eStep 1: Methanol Adsorption and Dehydrogenation\u003c/p\u003e\n \u003cp\u003eThe high dehydrogenation activity of Pt accelerated methanol conversion to methoxy species, while the synergy between Cu and Pt synergistically catalyzed the reaction, lowering the activation energy.\u003c/p\u003e\n \u003cp\u003eCH\u003csub\u003e3\u003c/sub\u003eOH \u0026rarr; CH\u003csub\u003e3\u003c/sub\u003eO\u003csup\u003e\u0026minus;\u003c/sup\u003e + H\u003csup\u003e+\u003c/sup\u003e\u003c/p\u003e\n \u003cp\u003eStep 2: Rapid Methoxy - to - Formaldehyde Conversion\u003c/p\u003e\n \u003cp\u003ePt promoted surface oxygen activation (O\u003csub\u003e2\u003c/sub\u003e \u0026rarr; 2O\u003csup\u003e\u0026minus;\u003c/sup\u003e), facilitating methoxy dehydrogenation.\u003c/p\u003e\n \u003cp\u003eCH\u003csub\u003e3\u003c/sub\u003eO\u003csup\u003e\u0026minus;\u003c/sup\u003e \u0026rarr; HCHO\u0026thinsp;+\u0026thinsp;H\u003csup\u003e+\u003c/sup\u003e\u003c/p\u003e\n \u003cp\u003eStep 3: Efficient Formaldehyde - to - Formic acid Conversion\u003c/p\u003e\n \u003cp\u003eFormaldehyde reacted with surface hydroxyl groups to form formic acid, which subsequently dissociated into formate species.\u003c/p\u003e\n \u003cp\u003eHCHO\u0026thinsp;+\u0026thinsp;H\u003csub\u003e2\u003c/sub\u003eO \u0026rarr; HCOOH\u003c/p\u003e\n \u003cp\u003eHCOOH \u0026rarr; HCOO\u003csup\u003e\u0026minus;\u003c/sup\u003e + H\u003csup\u003e+\u003c/sup\u003e\u003c/p\u003e\n \u003cp\u003eStep 4: Rapid Decomposition of Formate\u003c/p\u003e\n \u003cp\u003ePt\u0026apos;s strong oxidizing ability inhibited formate accumulation and promoted its rapid conversion to CO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e\n \u003cp\u003eHCOO\u003csup\u003e\u0026minus;\u003c/sup\u003e + 1/2 O\u003csub\u003e2\u003c/sub\u003e \u0026rarr; CO\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e\n \u003cp\u003eParallel Pathways:\u003c/p\u003e\n \u003cp\u003eCO Oxidation: Pt preferentially adsorbed and rapidly oxidized CO.\u003c/p\u003e\n \u003cp\u003eCO\u0026thinsp;+\u0026thinsp;O\u003csup\u003e\u0026minus;\u003c/sup\u003e \u0026rarr; CO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003cp\u003eEnhanced Carbonate Decomposition: Strong Pt-Cu interfacial interactions promoted CO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e decomposition.\u003c/p\u003e\n \u003cp\u003eCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e \u0026rarr; CO\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;O\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eCu/Pt/SSZ-13 catalyst, prepared by sequential impregnation (Pt first, Cu second), selectively oxidized methanol to CO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO at 160\u0026deg;C with minimal byproduct formation, thereby effectively controlling CH\u003csub\u003e3\u003c/sub\u003eOH emissions from methanol-fueled engines. Additionally, Cu/Pt/SSZ-13 catalyst demonstrated excellent SO\u003csub\u003e2\u003c/sub\u003e resistance and maintained high activity during simultaneous denitration and methanol removal, highlighting its potential as a multifunctional catalyst. Characterization studies revealed that Pt was preferentially dispersed on the carrier surface in the form of PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e species. Meanwhile, the strong anchoring effect of Pt promoted the uniform dispersion of the subsequently introduced small-sized CuO nanoclusters. The rational distribution of Pt and Cu species endowed the Cu/Pt/SSZ-13 catalyst with a larger pore size and higher specific surface area, providing ideal pathways for reactant diffusion and intermediate conversion. Furthermore, the Cu/Pt/SSZ-13 catalyst exhibited a high density of strong alkaline sites and an elevated proportion of surface-adsorbed oxygen, which originated from the synergistic interfacial effects between PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e and CuO species. It was synergy facilitated the rapid generation of active oxygen species, accelerating methanol dehydrogenation and deep oxidation. In situ DRIFTS results confirmed that Cu/Pt/SSZ-13 catalyst suppressed the deposition of formate intermediates while promoting the rapid conversion of formaldehyde intermediates to CO\u003csub\u003e2\u003c/sub\u003e. This study demonstrated the efficient methanol removal performance of a cost-effective Pt-modified Cu/SSZ-13 catalyst, which provides a new strategy for designing CH\u003csub\u003e3\u003c/sub\u003eOH-SCO catalysts that can effectively reduce CH\u003csub\u003e3\u003c/sub\u003eOH emissions from methanol/diesel engines while minimizing undesirable by-products during CH\u003csub\u003e3\u003c/sub\u003eOH oxidation.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eSCO Selective catalytic oxidation\u003c/p\u003e\n\u003cp\u003eCH\u003csub\u003e3\u003c/sub\u003eOH-SCO selectively catalyzed oxidation of CH\u003csub\u003e3\u003c/sub\u003eOH\u003c/p\u003e\n\u003cp\u003eNH\u003csub\u003e3\u003c/sub\u003e-SCO Selective catalytic oxidation of ammonia\u003c/p\u003e\n\u003cp\u003eXRD X-ray diffraction\u003c/p\u003e\n\u003cp\u003eSEM Scanning electron microscopy\u003c/p\u003e\n\u003cp\u003eEDS Energy dispersive X-ray\u003c/p\u003e\n\u003cp\u003eXPS X-ray photoelectron spectra\u003c/p\u003e\n\u003cp\u003eUV-Vis/DRS Ultraviolet–Visible Diffuse Reflectance Spectroscopy\u003c/p\u003e\n\u003cp\u003eH\u003csub\u003e2\u003c/sub\u003e-TPR H\u003csub\u003e2\u003c/sub\u003e temperature programmed reduction\u003c/p\u003e\n\u003cp\u003eCO\u003csub\u003e2\u003c/sub\u003e-TPD CO\u003csub\u003e2\u003c/sub\u003e temperature programmed desorption\u003c/p\u003e\n\u003cp\u003eIn-situ DRIFTS In-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy\u003c/p\u003e\n\u003cp\u003eSCR selective catalytic reduction\u003c/p\u003e\n\u003cp\u003eNPs nanoparticles\u003c/p\u003e\n\u003cp\u003eEGR Exhaust Gas Recirculation\u003c/p\u003e\n\u003cp\u003eCHA chabazite\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors gratefully acknowledge for the financial support from the Guangdong Province Natural Resources Project (2022-32) and the National Natural Science Foundation of China (52271356).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eQingliang Zeng: Conceptualization, Methodology, Formal analysis, Data curation, Writing-original \u0026amp; draft. Zhitao Han: Methodology, Writing-review \u0026amp; editing, Project administration, Funding acquisition. Tingjun Liu: Investigation, Resources. Shoujun Zhang: Investigation, Resources. Shaoqin Sheng: Investigation, Resources. Liangzheng Lin: Investigation, Resources. Junhao Jing: Investigation, Resources. Sihan Yin: Investigation, Resources.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by Guangdong Province Natural Resources Project (2022-32), National Natural Science Foundation of China (52271356).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo datasets were generated or analysed during the current study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u0026nbsp;\u003c/strong\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics and Consent to Participate\u0026nbsp;\u003c/strong\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for Publication\u003c/strong\u003e\u0026nbsp; Not applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eTian Z, Wang Y, Zhen X, Liu Z (2022) Fuel 320:123902.\u003c/li\u003e\n \u003cli\u003eMa B, Yao A, Yao C, Wang W, Ai Y (2021) Appl Energy 300:117355.\u003c/li\u003e\n \u003cli\u003eMohan S, Dinesha P, Kumar S (2020) Chem Eng J 384:123253.\u003c/li\u003e\n \u003cli\u003eWang Y, Zhu T, Zhao Y, Hao X (2024) J. 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63:e202403179.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"catalysis-letters","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Catalysis Letters](https://link.springer.com/journal/10562)","snPcode":"10562","submissionUrl":"https://submission.springernature.com/new-submission/10562/3","title":"Catalysis Letters","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"CH3OH-SCO, Cu/Pt/SSZ-13, PtOx, CuO, formate","lastPublishedDoi":"10.21203/rs.3.rs-6991891/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6991891/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe use of methanol as an alternative fuel for marine diesel engines increases unregulated CH\u003csub\u003e3\u003c/sub\u003eOH emissions. A series of Pt-modified Cu/SSZ-13 catalysts were prepared using different impregnation method, which selectively catalyzed oxidation of CH\u003csub\u003e3\u003c/sub\u003eOH (CH\u003csub\u003e3\u003c/sub\u003eOH-SCO) to CO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO. Activity tests showed that Cu/Pt/SSZ-13 catalyst (Pt impregnated first, followed by Cu) displayed exceptional CH\u003csub\u003e3\u003c/sub\u003eOH-SCO performance, achieving 100 % methanol conversion at 150 °C with negligible CO and HCHO byproduct formation (\u0026lt; 5 ppm) across the tested temperature range. Additionally, Cu/Pt/SSZ-13 catalyst exhibited excellent SO\u003csub\u003e2\u003c/sub\u003e resistance and high synergistic activity for simultaneous CH\u003csub\u003e3\u003c/sub\u003eOH and NO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e removal. Characterization results demonstrated that Cu/Pt/SSZ-13 catalyst exhibited larger pore size, higher specific surface area, abundant strong alkaline site density and elevated surface-adsorbed oxygen (O\u003csub\u003e\u003cem\u003eads\u003c/em\u003e\u003c/sub\u003e) proportion. It was originated from the preferential introduction of Pt and subsequent doping of Cu enhanced the synergistic interaction at the interface of PtO\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e and CuO species, which facilitated the rapid migration of reactive oxygen species, thus accelerating the methanol dehydrogenation and deep oxidation. In-situ DRIFTS results indicated that Cu/Pt/SSZ-13 inhibited the deposition of formate while promoting the rapid conversion of intermediates such as formaldehyde and formic acid to CO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e","manuscriptTitle":"Selective catalytic oxidation of methanol on Pt-modified Cu/SSZ-13 zeolites: A strategy to change the catalytic performance by impregnation sequential","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-11 07:33:20","doi":"10.21203/rs.3.rs-6991891/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-07-22T17:46:40+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-22T07:06:39+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-07-14T09:01:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"54515974606682820195191588352182124118","date":"2025-07-08T07:55:59+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"71399939941258433894344220316074152952","date":"2025-07-08T00:11:39+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-07-07T18:45:08+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-01T13:09:25+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-07-01T13:07:28+00:00","index":"","fulltext":""},{"type":"submitted","content":"Catalysis Letters","date":"2025-06-27T12:57:40+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"catalysis-letters","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Catalysis Letters](https://link.springer.com/journal/10562)","snPcode":"10562","submissionUrl":"https://submission.springernature.com/new-submission/10562/3","title":"Catalysis Letters","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"29781fe6-972a-4245-9b95-33425b4c3f71","owner":[],"postedDate":"July 11th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-08-17T19:23:26+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-11 07:33:20","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6991891","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6991891","identity":"rs-6991891","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}