Optimizing Ceria Promotion in Ni-Based Molecular Sieve Catalysts for Enhanced Hydrogen Production via Methane Partial Oxidation

Optimizing Ceria Promotion in Ni-Based Molecular Sieve Catalysts for Enhanced Hydrogen Production via Methane Partial Oxidation | 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 Optimizing Ceria Promotion in Ni-Based Molecular Sieve Catalysts for Enhanced Hydrogen Production via Methane Partial Oxidation Abdulaziz Al-Anazi, Amal BaQais, Kenit Acharya, Ahmed I. Osman, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6680604/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Methane is one of the potent greenhouse gas which contributes to global warming deadly. Its emission cannot be stopped as it comes from various natural wetlands and anaerobic decomposition processes. Methane can be partially oxidized with a Ni-stabilized CBV20A molecular sieve (SiO 2 /Al 2 O 3 = 20) to produce hydrogen-rich syngas. The Ni catalyst is located at charge compensation sites and inside the molecular sieve's pores. The catalysts are characterized by X-ray diffraction, surface area & porosity, FTIR, Raman spectroscopy, thermogravimetry analysis, transmission electron microscopy, and temperature programmed reduction/desorption/oxidation techniques. It was revealed that 2 wt.% ceria addition over 5Ni/CBV20A induced higher surface area and total active sites than 1 wt.% ceria promoted 5Ni/CBV20A. Over 5Ni2Ce/CBV20A, the concentration of active sites obtained from "NiO under moderate interaction" is at its peak. The metal-support interaction is further enhanced by the periodic exposure of hydrogen and oxygen during POM. 5Ni2Ce/CBV20A exhibits 2.5 H 2 /CO, 65% H 2 yield, and 65% CH 4 methane conversion. High catalytic activity and the generation of hydrogen-rich syngas demonstrate the potential of Ni-based catalysts supported on a molecular sieve with a Ce promoter for POM. Molecular sieve Syngas Zeolite Ce promoter POM Hydrogen yield Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction The Earth has warmed up by about 1 ℃ since the preindustrial era [1]. The 1.5 ℃ global warming threshold is expected to be reached by 2035 [2]. Over the next decade, the Earth will continue to warm, leading to high-impact climate changes such as sudden drought and floods, a rise in record sea levels, and severe disturbance in seasonal cycles [3]. The Paris Climate Agreement seeks to keep global warming less than 2 ℃ by the end of this century via mitigating greenhouse gases [4]. Interestingly, methane (CH 4 ) is approximately 25 times more potent than CO 2 as a greenhouse gas [5], but it can be effectively converted into syngas by partial oxidation of methane (POM), which lowers methane levels and generates a markedly high H 2 /CO ratio using molecular oxygen. Due to its low cost, nickel-based catalysis for POM consistently attracts more attention than catalysts based on noble metals. The different pathways of POM across Ni-based catalysts are shown in Fig. 1. Under oxidizing gas O 2 and reducing gas H 2 , Ni and NiO are interchangeable [6, 7]. Syngas is created via direct pathways where a mixture of CH 4 and O 2 is partially oxidized over metallic Ni. An pathways of syngas formation is discussed via indirect pathway where “CH 4 and O 2 ” is catalyzed by NiO into “CO 2 and H 2 O” (Total oxidation of CH 4 ; TOM) and thereafter CO 2 or H 2 O oxidizes CH 4 into syngas [8–10]. Methane can serve as a valuable resource for hydrogen production by properly utilizing the catalyst and reaction conditions to reach the appropriate H 2 /CO ratio. A proper metal oxide support gives a ground for fine dispersion of Ni and creating large number of active sites for POM reaction. Ni supported over basic oxides like MgO forms NiO-MgO solid solution, which is difficult to reduce and deactivate fast in POM reaction [9]. Ni supported over redox support like La 2 O 3 and TiO 2 is prone to oxidation of Ni active sites [10–12]. Compared to zirconia and alumina, the active metal Ni is less widely distributed over silica [13, 14]. Because of their quick phase transition at high temperatures, zirconia-based catalysts are likewise not advised for use as supports. Ni/Al 2 O 3 catalysts work better at POM because they have more weak and medium Lewis acid sites [15]. Here, the active sites of metallic Ni are supposed to be stabilized by surface unsaturated pentahedral coordination Al 3+, resulting in sinter resistance and coke resistance [16]. The ZSM-5 type zeolites are alumina-silicate populated with Brønsted sites rather than Lewis sites of alumina [15], and Ni/ZSM-5 performance towards POM was found to be better than Ni/Al 2 O 3 . When Ce and Ni are combined, a Ni-CeO 2 interface is formed, which quickly supplies lattice oxygen for the oxidation of CH 4 and improves catalytic efficiency [17]. Different silica-alumina ratios and synthetic conditions can be used to adjust the pore models of molecular sieves, which are artificial zeolites [18]. A molecular sieve allows only small molecules to pass through as well, and its specific pore architecture stabilizes the active sites against high-temperature conditions. Molecular sieve support for Ni-based catalyst application could be a viable solution for POM-like reactions occurring between 500 and 800 °C. Herein, the CBV20A molecular sieve (SiO 2 /Al 2 O 3 = 20, surface area = 500 m 2 /g) was investigated for supporting the active sites “Ni (5wt.%)” for catalytic application towards POM. The catalyst of 5Ni/CBV20A was promoted with 1-3 wt.% ceria to boost oxidizing potential. The 5Ni/CBV20A and 5NixCe/CBV20A (x = 1-3 wt.%) catalysts were characterized by surface characterization techniques (like N 2 adsorption-desorption isotherms, temperature programmed reduction/oxidation), spectroscopic techniques (like X-ray diffraction, Infrared and Raman) and thermogravimetric analysis. The practical use of a ceria-promoted molecular sieve for Ni-based catalysis towards POM was demonstrated through the correlation between structural properties and catalytic performance. 2. Experimental 2.1. Materials Ni(NO₃)₂·6H₂O (98%, Alfa Aesar), Ce(NO₃)₃·6H₂O (98%, Daiichi Kigenso Kagaku Kogyo Co. Ltd.), CBV20A (Zeolyst), and deionized water. 2.2. Catalyst Preparation The incipient wetness impregnation method is applied in catalyst preparation. Ni (NO 3 ) 2 ·6H 2 O solution (equivalent to 5 wt.% Ni) and Ce(NO₃)₃·6H₂O solution (equivalent to 1-3 wt.% Ce) are added in a beaker and stirred continuously while being heated. Further, 1 g CBV20A artificial molecular sieve is added to the solution and the solution is stirred continuously for 3 h under heating. The metal precursor solution is dispersed over the surface as well as inside the pores of the molecular sieves. The slurry is further dried at 120 o C for 3 h. The dried sample was calcined in air at 600 °C for 3 h. The target of calcination is to bring out metal oxide phases from the precursors' solution and products of their interaction with a support, as well as to remove the water molecules from the lattice. Up to 600 °C calcination temperature, the precursors give rise to both cerium oxide and nickel oxide, and all water molecules are removed from the lattice as well [19, 20]. The produced powdered catalysts are denoted as 5Ni/CBV20A and 5NixCe/CBV20A for convenience, with the Ni loading set at 5 weight percent and the Ce loading "x" varying between 1 and 3 weight percent. S1 and S2, which outline the catalyst characterization and evaluation test, are included in the additional file [21]. 3. Results and Discussion 3.1. Characterization Results and Discussion Figure 2 and Table 1 display the surface area parameters and pore size distribution over 5Ni/CBV20A and 5NixCe/CBV20A (x = 1–3 wt.%) catalysts. The slit-type mesopores are confirmed in catalyst through type IV isotherm having H3 hysteresis loop. The pore size distribution plots reveal a monomodal distribution of pore in 3.72–4 nm sizes range which is a typical mesopores range. Nonetheless, the average pore size is more wider (~ 7.2 nm). Non-promoted catalyst attains maximum surface area (373 m 2 /g), and pore volume (0.130 cm 3 /g). In contrast, the 1 weight percent Ce-promoted 5Ni/CBV20A catalyst's surface area and pore volume significantly shrank. This suggests that ceria nanocrystallites may have blocked the pore structure. Unexpectedly, the surface area increased at 2 wt.% Ce, potentially due to improved dispersion of Ni species. It seems that 2 wt.% ceria addition induced finer dispersion of Ni over the CBV20A support. Following additional loading of ceria (3 wt.%) over 5Ni/CBV20A, the pore volume and surface area abruptly decreased to 0.124 cm 3 /g and 346 m 2 /g, respectively. It seems that the higher loadings of ceria did not induce Ni’s dispersion, although the ceria crystallites were readily deposited in the pores. Table 1 The BET surface area, pore volume, and average pore size of 5Ni/CBV20A and 5NixCe/CBV20A (x = 1–3 wt.%) catalysts. Sample Surface Area (m 2 /g) Pores Volume (cm 3 /g) Average Size of Pores (nm) 5Ni/CBV20A 373 0.130 7.2 5Ni1Ce/ CBV20A 351 0.128 7.11 5Ni2Ce/ CBV20A 364.6 0.129 7.21 5Ni3Ce/ CBV20A 346.2 0.124 7.16 Figure S1 and Fig. 3 A display the X-ray diffraction of CBV20A, 5Ni/CBV20A, and 1–3 wt.% ceria promoted 5Ni/CBV20A. Upon the addition of Ni over the molecular sieve (CBV20A), the intensity of diffraction patterns decreased readily, whereas the 5Al 2 O 3 ·NiO phase appeared markedly. The 5Ni/CBV20A shows the characteristic peaks for commercial mordenite at 6.6 ̊, 8.7 ̊, 9.8 ̊, 13.6 ̊, 14.6 ̊, 15.3 ̊, 19.7 ̊, 22.5 ̊, 23.2 ̊, 23.7 ̊, 25.8 ̊, 26.5 ̊, 27.8 ̊, 31 ̊, and 35.8 ̊ [22], and monoclinic 5Al 2 O 3 ·NiO phase (NiAl 10 O 16 phase) at 38 ̊ and 44.4 ̊ Bragg’s angle (JCPDS reference number 00-037-1292). XRD data revealed the close interaction of “NiO and Al 2 O 3 ”. The intensity of the mordenite peaks increased when ceria was added up to 2 wt.% to the 5Ni/CBV20A. It suggests that when ceria is loaded, the mordenite framework is strengthened. The intensity of diffraction pattern for the distinctive mordenite peak decreased with further ceria loading (up to 3 wt.%). Over the 5Ni3Ce/CBV20A, the intensity of the crystalline peaks for the monoclinic 5Al 2 O 3 ·NiO phase consistently decreased. This indicates that ceria enhanced the dispersion of NiO species within the composite material. Figure 3 E displays the 5Ni/CBV20A and 5NixCe/CBV20A (x = 1–3 weight percent) catalysts' Raman vibration spectra. Raman vibrations of Si-O are clearly visible in the 5Ni/CBV20A catalyst at 283 cm − 1 , 403 cm − 1 , 511 cm − 1 , 856 cm − 1 , 928 cm − 1 , 1051 cm − 1 , and 1160 cm − 1 . While Si/Si and Al/Al translational lattice modes are shown at 139 cm − 1 [ 23 , 24 ]. The Raman vibration of Al-O is visible at 679 cm − 1 [ 25 , 26 ]. Curiously, the Si-O or Al-O vibrational peaks decreased with the promotional addition of 1–2 weight percent Ce, and their intensity was negligible at 3 weight percent ceria loading. It shows that when ceria is added, the polarisability of Si-O and Al-O bonds decreases. It is due to less distortion of electrons over Si-O and Al-O from their original positions. Strong Si-O (or Al-O) interactions or the development of a strong covalent bond between Si-O (or Al-O) are responsible for the low polarisability in silica and alumina [ 27 ]. Figure 3 F displays the FTIR spectra of 5Ni/CBV20A and 5NixCe/CBV20A (x = 1–3 weight percent). The distinctive mordenite peaks at 460 cm − 1 , 565 cm − 1 , 800 cm − 1 , and 1100 cm − 1 are visible in all catalysts [ 28 ]. For bending and stretching hydroxyl, the vibration peaks are shown as a broad band at 3427 cm − 1 and a sharp peak at 1630 cm − 1 , respectively [ 29 ]. Shoulder peaks at 3625 cm − 1 are also identified as proton-donating sites, such as Brønsted acid sites [ 30 ]. Figure 3 G shows the TGA results for each catalyst. Due to water desorption, it exhibits constant weight loss up to 200–300°C [ 31 ]. There is a slight weight loss of 5.05 to 7.17 percent over 5Ni/CBV20A and 5NixCe/CBV20 (x = 1–3 weight percent) after 300°C. The reduction of 5Ni/CBV20A and 5NixCe/CBV20A (x = 1–3 weight percent) was performed using an H 2 -temperature program and shown in Fig. 4 A and Table 2 . It offers Ni and the support a special level of interaction. A non-promoted catalyst's reduction profile consists of a large peak at roughly 450°C and a diffuse peak at roughly 322°C. SiO 4 tetrahedra and AlO 4 tetrahedra are building block of crystalline framework of alumino-silicates where silica is tetravalent, and alumina is trivalent. Successive substitution of tetravalent silicon by a trivalent aluminum atom generates an extra anionic charge. To achieve charge neutrality, cationic species (like Ni 2+ ) compensate with the resulting negative lattice charge [ 32 ]. Therefore, the reduction of Ni 2+ (or NiO) isolated within the charge compensation sites is responsible for the low-temperature reduction (322°C). One could refer to this NiO-support interaction as a moderate one. NiO is deposited over the molecular sieve at a location encircled by different cages of the mordenite-based molecular sieve, which strengthens the metal-support interaction. A comparatively stronger metal-support interaction of NiO is indicated by the reduction peak at higher temperature (450 o C). Remarkably, after addition of 1 wt. % ceria over Ni-supported molecular sieve, the low-temperature reduction peak is intensified while the overall H 2 consumption stays the same (15 cm 3 /g). It suggests that, compared to a non-promoted catalyst, the inclusion of ceria causes generation of more reducible NiO at charge compensation sites of CBV20A. The H 2 consumption increases significantly (19 cm 3 /g) when 2 wt % ceria is loaded on 5Ni/CBV20A. Additionally, the reduction peak at low-temperature intensifies more than the reduction peak at high-temperature. It shows that more reducible NiO species are being produced charge compensation sites of CBV20A. However, the strength of the high-temperature reduction peak is amplified, and the overall H 2 consumption reaches its maximum (20.9 cm 3 /g) with the highest loading of ceria (3 wt.%). For ceria-based catalysts, reducible surface capping oxygen has also been reported to exhibit a reduction peak at around 400–500°C [ 33 – 35 ]. Therefore, the development of the reduction peak at roughly 450°C could be the result of both the reduction of reducible surface capping oxygen and the combined contribution of reducible NiO under strong metal-support interaction. The H 2 -TPR of the new catalyst is typically used to characterize a catalyst's reducibility profile. O 2 is the oxidant in POM, though, and it can oxidize both metallic "Ni" into NiO and the carbon deposit into syngas [ 6 ]. Consequently, Ni's active sites become inactive. The complete oxidation of methane is catalyzed by NiO [ 8 ]. H 2 gas is also produced during the DRM reaction (as a component of syngas), which aids in preserving Ni's metallic phase once more. Overall, the catalyst reduction behavior may be altered by sequential treatment of oxidizing gas (O 2 ) and reducing gas (H 2 ). To understand the reduction-oxidation-reduction profile H 2 TPR-O 2 TPO-H 2 TPR cyclic experiment is conducted over 5Ni/CBV20A and a 2-weight percent ceria promoted 5Ni/CBV20A catalyst (Fig. 4 B-C). Following a series of reduction-oxidation-reduction treatments, the 5Ni/CBV20A catalysts' reduction profiles are enhanced and expanded to higher temperatures (600°C). The disappearance of the reduction peak in low-temperature region and appearance of reduction peak in high-temperature region (about 600°C) during the last H 2 -TPR (in the cyclic experiment) can be used to specify the reduction profile of the 5Ni2Ce/CBV20A catalyst in the co-presence of oxygen and hydrogen. It shows that the reductive and oxidative gas stream (during POM) induce stronger metal-support interaction at the expense of weak metal-support interaction over the ceria-promoted 5Ni/CBV20A catalyst. Figure 4 D shows the results of CO 2 temperature-programmed desorption (TPD). The acidic gas CO₂ is adsorbed over the basic sites of catalyst. The surface hydroxyl groups generate weak basic sites which interacts with CO 2 . These interacted-CO 2 is desorbed at lower temperatures (< 200°C) in CO 2 -TPD. Similarly, basic surface oxide anions contribute to the moderate strength basic site which interact CO 2 with stronger strength. These interacted-CO 2 is desorbed in the intermediate temperature range (~ 200–400°C) [ 36 ]. The decomposition of carbonates is responsible for the CO 2 desorption peak above 400°C [ 37 ]. These basic sites can be referred to as strong basic sites. Interestingly, the non-promoted catalyst (5Ni/CBV20A) has the largest population of moderate-strength basic sites but a diffuse population of strong basic sites. The population for moderate-strength basic sites is comparatively decreased as ceria loading increases over 5Ni/CBV20A. Decomposable surface carbonate's peak intensity rises when 1 weight percent Ce is added over 5Ni/CBV20A. According to reports in the literature, ceria also interacts with CO 2 and forms surface carbonate and surface carboxylates quickly [ 38 ]. It should be noted that the apex of strong basic sites is absent at 2 weight percent ceria loading over 5Ni/CBV10A. Again, in 3 wt.% ceria, such strong basic sites are observed with relatively lower intensity (than 5Ni1Ce/CBV20A). Therefore, it may be concluded that at 2 wt.% of ceria-promoted 5Ni/CBV20 catalyst, either no surface carbonate forms or a stable, non-decomposable surface carbonate forms. Ce 2 (CO 3 ) 3 has been reported in the literature as a stable structure; nonetheless, it can decompose at 700 °C [ 38 ]. This absence of a CO₂ desorption peak between 500 and 900°C suggests the 5Ni2Ce/CBV20A catalyst lacks decomposable surface carbonate species. Table 2 The total quantity of H 2 consumption by the catalyst during the H 2 -TPR experiment. Name of Catalyst Total H 2 Quantity Used (cm³/g STP) 5Ni/CBV20A 14.97 5Ni1Ce/CBV20A 15.00 5Ni2Ce/CBV20A 19.08 5Ni3Ce/CBV20A 20.90 Figure 5 displays the particle size distribution and transmission electron microscopy images of fresh and spent 5Ni/CBV20A and 5Ni2Ce/CBV20A. The particle size of fresh 5Ni/CBV20A and 5Ni2Ce/CBV20A catalysts was 8.2 nm and 9.17 nm, respectively. Over spent 5Ni/CBV20A and 5Ni2Ce/CBV20A catalysts, particle sizes increased to 9.2 and 10.5 nm, respectively. The particle size increased during the POM reaction over both 5Ni/CBV20A and 5Ni2Ce/CBV20A catalysts. The increase in particle size during the POM process was attributed to the thermal sintering of Ni metal under high-temperature reaction conditions. 3.2. Results of Catalytic Activity and Discussion The CBV20A, a mordenite-type molecular sieve, has a silica-alumina ratio of 20 and a large surface area of 500 m 2 /g. It is used to support 5 wt.% Ni. Additionally, 1–3 wt.% ceria is used as a promoter over 5Ni/CBV20A to modify the reducibility, basicity, and crystallinity. The formation of 5Al 2 O 3 .NiO phase over each catalyst shows the intimate interaction of NiO over an alumina-silicates framework of molecular sieve. Figure 6 displays the catalytic activity for POM over 5Ni/CBV20A and 1–3 wt.% ceria-promoted 5Ni/CBV20A catalysts. The catalytic system exhibited an H₂/CO ratio ranging from 2.4–2.6 H 2 /CO ratio, > 40% H 2 yield, > 20% CO 2 production, and > 60% CH 4 conversion. The stoichiometric ratio of H 2 to CO in a direct POM reaction should be 2, but in this case, it is greater than 2. This suggests that the direct POM response routes are not the only pathways. Once more, a yield of more than 20% CO 2 across all catalyst systems suggests that complete oxidation of CH 4 by O 2 occurs easily. While metallic Ni is a catalytically active site for DRM and SRM, NiO has been shown to catalyse TOM. Therefore, there is a chance that CH 4 will once more interact with the total oxidation products (CO 2 & H 2 O). Indirect POM pathways may proceed via sequences such as TOM followed by DRM or SRM. 5Ni/CBV20A catalyst acquired high crystallinity, the largest surface area and pore volume where active sites originate. NiO is interacted with CBV20A support through strong and moderate interaction. After reduction, these interacted-NiO species generates metallic Ni as active sites. Remarkably, the total concentration of active sites rose, and the metal-support interaction improved under O 2 and H 2 gases (verified by H 2 TPR-O 2 TPO-H 2 TPR cyclic experiment). The 5Ni/CBV20A catalyst attains the highest concentration of moderate-strength basic sites. The basic sites are needed for the interaction of CO 2 and H 2 O (the product of TOM) and the re-engagement of these gases as oxidants for methane oxidation under indirect pathways. Overall, 5Ni/CBV20A shows 63% CH 4 conversion and 40% H 2 yield with a 2.6 H 2 /CO ratio at the end of 230 minutes. After adding 1 wt.% ceria over 5Ni/CBV20A, the covalent bond between Si-O and Al-O becomes stronger (verified by Raman), the crystallinity of mordenite framework increased relatively, the strong basic sites’ concentration was intensified, the surface area and pore volume decreased and the total amount of active sites remained constant than the non-promoted catalyst. Interestingly, CH 4 conversion and CO 2 yield over 5Ni1Ce/CBV20A remain similar to 5Ni/CBV20A catalyst. Since the total concentration of active sites “Ni” remains the same, the ability of 5Ni1Ce/CBV20A to activate C–H bonds in CH₄ remains comparable to that of the non-promoted catalyst. However, the concentration of active sites derived from “NiO under moderate interaction” is growing, as well as a catalyst is also populated by strong basic sites. In comparison to the 5Ni/CBV20A catalyst, the H 2 and CO yields over 5Ni1Ce/CBV20A catalyst are improved by 50–60%. The crystallinity of the mordenite framework increases comparatively when 2 weight percent ceria loading is applied over 5Ni/CBV20A. Furthermore, compared to previous ceria loadings, the fine dispersion at 2 wt.% ceria loading produces an increased surface area and pore volume. It is filled with basic sites of moderate strength. The population of "NiO under moderate interaction" and the total population of active sites are highest over 5Ni2Ce/CBV20A. The metal-support interaction of NiO is strengthened in the presence of reducing gas (H 2 ) and oxidizing gas (O 2 ), which increases the concentration of stable active sites for the POM reaction. Figure 7 depicts the direct and indirect paths of the POM reaction over 5Ni2Ce/CBV20A. The partial oxidation of methane by O 2 (POM routes) is catalyzed by the concentration of metallic Ni, whereas the complete oxidation of CH 4 by O 2 (TOM) is catalyzed by the concentration of NiO throughout the reaction. Under indirect pathways of POM, CO 2 oxidizes CH 4 into syngas by the DRM reaction over the metallic Ni, and H 2 O oxidizes CH 4 into syngas over metallic Ni through the SRM process. A ceria loading of 2 wt.% was found to be optimal, and it achieves about 65% CH 4 conversion and 62% H 2 yield with a 2.5 H 2 /CO ratio at the end of 230 minutes. Over 5Ni3Ce/CBV20A, the crystallinity of the mordenite framework decreased, and the catalysts’ surface area and pore volumes decreased significantly. Still, it has the highest concentration of reducible species, including the reducible ceria. It has an adequate concentration of strong basic sites/surface carbonates. The H 2 yield drops to 58% over 5Ni3Ce/CBV20A, whereas the CO 2 yield reaches its maximum value of 25%. While metallic Ni catalyzes the direct POM, DRM, and SRM reactions, NiO catalyzes the complete oxidation of CH 4 into CO 2 . By oxidizing the Ni to NiO, the excess ceria may promote total oxidation and inhibit the DRM/SRM process in indirect POM route. Notably, CH₄ conversion over 5Ni3Ce/CBV20A is even lower than that of the non-promoted catalyst, suggesting excessive ceria loading may block active sites, limiting catalytic performance [ 39 ]. The current catalyst system's activity is contrasted with that of the POM catalyst systems that have been published (Table 3 ). LaNiO 3 's H 2 -yield and H 2 /CO ratio are found to be more competitive than those of the current catalyst, 5Ni2Ce/CBV20A, under comparable conditions. However, POM operates at a higher temperature (700°C) than the LaNiO 3 catalyst, and it requires five times more catalyst mass for the reaction than the existing catalytic system. Overall, at 600°C reaction temperature and 100 mg catalyst amount, the present catalyst, 5Ni2Ce/CBV20A, outperforms than others. Table 3 The comparison of catalytic activity of the catalyst system with reported catalyst system towards partial oxidation of methane reaction. . No. Catalyst RT ( o C) WM (wt.%) CW (mg) Flow rate (cm 3 /min) TOS (Min) \(\:{\varvec{X}}_{{\varvec{C}\varvec{H}}_{4}}\) (%) \(\:{\varvec{Y}}_{{\varvec{H}}_{2}}\) (%) H 2 /CO Ref. CH 4 CO 2 Inert gas 1 5Ni/30TiO 2 + ZrO 2 600 5 100 2 1 1 240 45 47 4.1 [ 40 ] 2 5Ni2.5Sr/30TiO 2 + ZrO 2 600 5 100 2 1 1 240 41 31 3.5 [ 40 ] 3 Mesoporous-LaNiO 3 700 3* 500 2 1 - 6000 75 60 2.35 [ 41 ] 4 Bulk-LaNiO 3 700 3* 500 2 1 - 6000 53 65 2.1 [ 41 ] 5 Ni/Al 2 O 3 - ZrO 2 600 2 25 2 1 10 3000 49 28 2.7 [ 42 ] 6 Ni/MgO 750 5 100 2 1 3 210 23 10 3.4 [ 42 ] 7 5Ni/La 2 O 3 -BFA 850 5 300 2 1 1 510 86 42 2.0 [ 12 ] 8 10Ni/La 2 O 3 -BFA 850 10 300 2 1 1 510 88 48 1.25 [ 12 ] 9 Ni/Al 2 O 3 600 2 25 2 1 10 3000 56 35 2.9 [ 42 ] 10 Ni/CeO 2 800 15 15 2 1 - 90 27.6 - - [ 17 ] 11 Ni/ZrO 2 650 2 25 2 1 10 3000 46 26 2.3 [ 42 ] 12 Ni/TiZr 600 5 100 2 1 1 300 40 30 4.27 [ 7 ] 13 Ni2Cs/TiZr 600 5 100 2 1 1 300 43 38 3.48 [ 7 ] 14 Ni2Ce/TiZr 600 5 100 2 1 1 300 41 31 3.84 [ 7 ] 15 Ni2Sr/TiZr 600 5 100 2 1 1 300 46 42 3.72 [ 7 ] 16 Fe (5)-NAL 600 5 100 2 2 0 270 60 31 - [ 43 ] 17 5Ni/SAPO-5 600 5 100 2 1 1 240 41.13 30 3.30 [ 44 ] 18 5Ni + 1Ce/SAPO-5 600 5 100 2 1 1 240 43.55 38 3.33 [ 44 ] 19 5Ni + 1Sr/SAPO-5 600 5 100 2 1 1 240 48.17 41.66 3.40 [ 44 ] 20 5Ni + 1Cu /SAPO-5 600 5 100 2 1 1 240 49.11 19 4.14 [ 44 ] 21 5Ni/CBV20A 600 5 100 2 1 1 230 63 40 2.6 Current Study 22 5Ni2Ce/CBV20A 600 5 100 2 1 1 230 65 62 2.5 BFA: Biomass Fly Ash, RT = Reaction Temperature, WM = weight % of active metal, * = Ni amount is shown in millimole, CW = Catalyst weight take for a reaction, TOS = Time on stream, \(\:{X}_{{CH}_{4}}\) = CH 4 conversion (%), \(\:{Y}_{{H}_{2}}\) = H 2 yield (%). 4. Conclusion The mordenite-based molecular sieve CBV20A (SiO₂/Al₂O₃ = 20) effectively anchors NiO, with its cage-like structure and charge-compensation sites contributing to stabilization. The unique 5Al 2 O 3 .NiO phase over the catalyst confirms the strong interaction of NiO with the alumina component of the molecular sieve. Exposure to reducing and oxidizing gases during POM increases the concentration of reducible species and improves the metal-support interaction. Moderate-strength basic sites found in 5Ni/CBV20A may facilitate interaction with CO₂ and H₂O (the development of total oxidation of methane) for indirect CH 4 oxidation. After 230 minutes, it yields 40% H 2 and 63% CH 4 conversion with a 2.6 H 2 /CO ratio. By increasing the covalent connection between Si-O and Al-O and enhancing the population of active sites (obtained from NiO under moderate interaction), a promotional addition of 1 wt.% ceria over 5Ni/CBV20A results in a 50–60% increase in H 2 yield without changing the H 2 /CO ratio. The overall number of active sites increases, and the population of active sites resulting from the "NiO under moderate interaction" reaches its peak at 2 weight percent ceria loading. During POM, the metal-support interaction of NiO is expanding under O 2 and H 2 gases. Without changing the H 2 /CO ratio under direct and indirect pathways for POM, 5Ni2Ce/CBV20A achieves a maximum of 65% CH 4 conversion and 62% H 2 yield (after 230 minutes). The significant decrease in surface properties and the possible oxidation of active sites by ceria are the principal reason of inferior catalytic activity towards POM and highest CO 2 -yield over 5Ni3Ce/CBV20A. The application of the ceria-promoted Ni-containing molecular sieve as a possible catalyst system for POM is demonstrated by the achievement of high CH 4 conversion (65%) and high H 2 yield (62%), with a notably high H₂/CO ratio of 2.6. Abbreviation POM: Partial oxidation of methane TOM: Total oxidation of methane DRM: Dry Reforming of Methane SRM: Steem Reforming of Methane TPR: Temperature Programmed Reduction TPO: Temperature Programmed Oxidation TOS: Time on Stream Declarations Ethical and Consent to Participate: In this research article, all experimental procedures, including the catalyst Preparation, catalyst Activity Test, and catalyst characterization, complied with laboratory safety protocols and institutional guidelines. No ethical approval was required for this work. Consent for Publication: All authors have reviewed the final version of the manuscript and given their consent for its submission for publication. The content of this paper, including Abstract, Experimental data, Figures, Conclusions, and Supplementary Materials, is original and has not been published elsewhere. Competing Interests: The authors declare no competing interests. Author Contributions: Abdulaziz Al-Anazi: Conceptualization, Investigation, Writing. Amal BaQais: Resources, Data curation. Kenit Acharya: Writing,Data curation, Investigation, Software. Omer Bellahwel : Resources, Formal analysis, Data curation. Ahmed I. Osman: Conceptualization, Investigation, Writing, Supervision, methodology, visualization. Ahmed A. Ibrahim: Data curation, Visualization, Software. Methodology, Formal analysis. Fekri Abdulraqeb Ahmed Ali : Review,Methodology, Formal analysis. Salwa B. Alreshaidan : Software, formal analysis, Resources. Ahmed E. Abasaeed: Investigation, supervision, methodology. Changseok Han : Data curation, Validation, Software. Rawesh Kumar: Data curation, Writing – review & editing. Ahmed S. Al-Fatesh: Data curation, Methodology, Writing, reviewing & editing, Funding acquisition, Project Administration. Funding: Researchers Supporting Project number (RSP2024R368), King Saud University. Data availability : Data are contained within the article and Supplementary Materials . Acknowledgments: The authors would like to extend their sincere appreciation to the Princess Nourah bint Abdulrahman University Researchers Supporting Project number (PNURSP2025R230), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia. Also, the authors would like to express their Wholehearted gratitude to King Saud University's Researchers for Supporting Project No. (RSPD2025R779). References Song F, Zhang GJ, Ramanathan V, Leung LR (2022) Trends in surface equivalent potential temperature: A more comprehensive metric for global warming and weather extremes. 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Int J Hydrogen Energy 46:25015 Siakavelas GI, Charisiou ND, AlKhoori S, et al (2021) Highly selective and stable nickel catalysts supported on ceria promoted with Sm2O3, Pr2O3 and MgO for the CO2 methanation reaction. Appl Catal, B 282:119562 Staudt T, Lykhach Y, Tsud N, et al (2010) Ceria reoxidation by CO2: A model study. Journal of Catalysis 275:181–185 Chaudhary ML, Al-Fatesh AS, Kumar R, et al (2022) Promotional effect of addition of ceria over yttria-zirconia supported Ni based catalyst system for hydrogen production through dry reforming of methane. International Journal of Hydrogen Energy 47:20838–20850. https://doi.org/10.1016/j.ijhydene.2022.04.199 Alwadai N, Abahussain AAM, Vadodariya DM, et al (2024) Ni–Sr/TiZr for H 2 from methane via POM: Sr loading & optimization. RSC advances 14:25273–25288 Duan Q, Wang J, Ding C, et al (2017) Partial oxidation of methane over Ni based catalyst derived from order mesoporous LaNiO3 perovskite prepared by modified nanocasting method. Fuel 193:112–118 Pompeo F, Nichio NN, Ferretti OA, Resasco D (2005) Study of Ni catalysts on different supports to obtain synthesis gas. International Journal of Hydrogen Energy 30:1399–1405 Abasaeed AE, Adil SF, Kuniyil M, et al (2024) FexOy Nanoparticles Doped Spinel Nickel Aluminate as Partial Oxidation Catalyst: Synthesis, Characterization and Catalytic Evaluation. Catalysis Letters 154:2829–2840 Al-Anazi A, Bellahwel O, Abu-Dahrieh J, et al (2024) Promoter Impact on 5Ni/SAPO-5 Catalyst for H2 Production via Methane Partial Oxidation. Catalysts 14:316 Additional Declarations No competing interests reported. Supplementary Files SupportinginformationCatalysisLetters.docx Fig. S1 X-ray diffraction pattern of CBV20A and 5Ni/CBV20A. 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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-6680604","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":459140152,"identity":"cca39894-3baa-4638-a43b-9d2618deff1f","order_by":0,"name":"Abdulaziz Al-Anazi","email":"","orcid":"","institution":"King Saud University","correspondingAuthor":false,"prefix":"","firstName":"Abdulaziz","middleName":"","lastName":"Al-Anazi","suffix":""},{"id":459140153,"identity":"af36cf06-399d-4f77-b56b-a7be90faa6d7","order_by":1,"name":"Amal BaQais","email":"","orcid":"","institution":"Princess Nourah bint Abdulrahman University","correspondingAuthor":false,"prefix":"","firstName":"Amal","middleName":"","lastName":"BaQais","suffix":""},{"id":459140154,"identity":"a1a38e4b-a24f-4f4f-a345-47e55f963949","order_by":2,"name":"Kenit Acharya","email":"","orcid":"","institution":"Indus University","correspondingAuthor":false,"prefix":"","firstName":"Kenit","middleName":"","lastName":"Acharya","suffix":""},{"id":459140155,"identity":"7fb0197e-769a-4cb2-b903-1cee370cd365","order_by":3,"name":"Ahmed I. 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Al-Fatesh","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7klEQVRIiWNgGAWjYFAC5oYPIMqAvQ3MZWwgrIWxcQZDAlALzzGStUikEamFv/1gY8PPHzb25pLPkj/zMNjIbjjA/vADPi0SZxIbG3sS0hJ3zk47Js3DkGa84QCPsQReaw4ktj/gSTicYHA7vY2Zh+FwIlALA14t8ucfNjb+Sfhvb3DzeDPQYf+BWtgf/8CnxeBGYmMzT8IBxg032A4AHXYAqIXBDK8thjceNjbLpCUnbjiTliY5xyDZeOZhHjMLfFrkzicfbHxjY2dvcPyY8Yc3FXayfcfbH9/ApwXdnUDMTIL6UTAKRsEoGAXYAQBLDFH2/hQVhAAAAABJRU5ErkJggg==","orcid":"","institution":"King Saud University","correspondingAuthor":true,"prefix":"","firstName":"Ahmed","middleName":"S.","lastName":"Al-Fatesh","suffix":""}],"badges":[],"createdAt":"2025-05-16 12:08:05","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6680604/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6680604/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":83213333,"identity":"3aca1bf7-aac5-4cff-9676-30936ee3e679","added_by":"auto","created_at":"2025-05-21 08:44:09","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":78189,"visible":true,"origin":"","legend":"\u003cp\u003ePOM's reaction scheme via direct and indirect channels. TOM stands for total oxidation of methane, POM for partial oxidation, DRM for dry reforming, and SRM for steam reforming.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6680604/v1/cacda001db1fabf87516f790.png"},{"id":83213334,"identity":"5e8cbbcf-babb-4d96-8182-092f1257d9e9","added_by":"auto","created_at":"2025-05-21 08:44:09","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":296145,"visible":true,"origin":"","legend":"\u003cp\u003eBET Plots of the pore size distribution and adsorption isotherms (A) 5Ni/CBV20A (B) 5Ni1Ce/CBV20A (C) 5Ni2Ce/CBV20A (D) 5Ni3Ce/CBV20A.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6680604/v1/4e7985d7b8740bdbc70c9f92.png"},{"id":83213344,"identity":"a0783684-4d7e-4661-ae06-6a670764d51a","added_by":"auto","created_at":"2025-05-21 08:44:09","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":3137343,"visible":true,"origin":"","legend":"\u003cp\u003eX-ray diffraction pattern of (A) 5Ni/CBV20A (B-D) 5Ni/CBV20A and 5NixCe/CBV20A (x = 1-3 weight percent) in selected Bragg's angle range. Raman spectra of (E) 5Ni/CBV20A and 5NixCe/CBV20A (x = 1-3 weight percent). FTIR spectra of (F) 5Ni/CBV20A and 5NixCe/CBV20A (x = 1-3 weight percent). Thermogravimetric analysis of (G) 5Ni/CBV20A and 5NixCe/CBV20A (x = 1-3 weight percent) catalyst.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6680604/v1/73481d790b30098efbc82107.png"},{"id":83213343,"identity":"a97fb7ca-d19c-4fdc-bdf4-b90fc5fc98c7","added_by":"auto","created_at":"2025-05-21 08:44:09","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":210612,"visible":true,"origin":"","legend":"\u003cp\u003e(A) H\u003csub\u003e2\u003c/sub\u003e-Temperature programmed reduction (H\u003csub\u003e2\u003c/sub\u003e-TPR) of 5Ni/CBV20A and 5NixCe/CBV20A (x = 1-3 wt.%) (B) Cyclic H\u003csub\u003e2\u003c/sub\u003eTPR-O\u003csub\u003e2\u003c/sub\u003eTPO-H\u003csub\u003e2\u003c/sub\u003eTPR experiment over 5Ni/CBV20A (C) Cyclic H\u003csub\u003e2\u003c/sub\u003eTPR-O\u003csub\u003e2\u003c/sub\u003eTPO-H\u003csub\u003e2\u003c/sub\u003eTPR experiment over 5Ni2Ce/CBV20A (D) CO\u003csub\u003e2\u003c/sub\u003e-temperature programmed desorption.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6680604/v1/ad4c80116f1913a8c203fe56.png"},{"id":83213354,"identity":"55c960e4-211c-4e34-9d24-70a89702b4e8","added_by":"auto","created_at":"2025-05-21 08:44:09","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":12560399,"visible":true,"origin":"","legend":"\u003cp\u003e(A-E): TEM images of fresh and spent catalysts: (A–E) fresh 5Ni/CBV20A, (F) particle size distribution of fresh 5Ni/CBV20A; (G–K) spent 5Ni/CBV20A, (L) its particle size distribution; (M–Q) fresh 5Ni2Ce/CBV20A, (R) its distribution; (S–W) spent 5Ni2Ce/CBV20A, (X) its distribution.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6680604/v1/f956f6b3fd41aa8e08c55958.png"},{"id":83214379,"identity":"cfcb58af-8ba7-4663-8697-e89e8bd5f376","added_by":"auto","created_at":"2025-05-21 08:52:09","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":215299,"visible":true,"origin":"","legend":"\u003cp\u003eThe 5Ni/CBV20A and 5NixCe/CBV20A catalytic activity (x = 1-3 wt.%) (A) conversion of CH\u003csub\u003e4\u003c/sub\u003e (B) H\u003csub\u003e2\u003c/sub\u003e yield (C) H\u003csub\u003e2\u003c/sub\u003e/CO ratio (D) CO\u003csub\u003e2\u003c/sub\u003e yield.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-6680604/v1/b02ce3241ccb6174dc0679b7.png"},{"id":83214378,"identity":"86cdf4f1-11c6-4523-8fa8-59f6823bb117","added_by":"auto","created_at":"2025-05-21 08:52:09","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":190730,"visible":true,"origin":"","legend":"\u003cp\u003eThe POM reaction's direct and indirect paths over a 5Ni2Ce/CBV20 catalyst are shown in the reaction scheme. TOM stands for total oxidation of methane, POM for partial oxidation, DRM for dry reforming, and SRM for steam reforming.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-6680604/v1/fd0af50994b628fec6c35c0f.png"},{"id":84062651,"identity":"aca97eab-76a8-41da-b332-c25dfd21d6a2","added_by":"auto","created_at":"2025-06-06 10:32:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":17009144,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6680604/v1/5b69c203-239c-48d9-aec3-23e5429031b4.pdf"},{"id":83215329,"identity":"9719b6ec-7fdc-4574-b25c-03d04ed9b622","added_by":"auto","created_at":"2025-05-21 09:00:09","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":306055,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFig. S1\u003c/strong\u003e X-ray diffraction pattern of CBV20A and 5Ni/CBV20A.\u003c/p\u003e","description":"","filename":"SupportinginformationCatalysisLetters.docx","url":"https://assets-eu.researchsquare.com/files/rs-6680604/v1/0f0bc8d053bc15648242d198.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Optimizing Ceria Promotion in Ni-Based Molecular Sieve Catalysts for Enhanced Hydrogen Production via Methane Partial Oxidation","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe Earth has warmed up by about 1 ℃ since the preindustrial era\u0026nbsp;[1]. The 1.5 ℃ global warming threshold is expected to be reached by 2035 [2]. Over the next decade, the Earth will continue to warm, leading to high-impact climate changes such as sudden drought and floods, a rise in record sea levels, and severe disturbance in seasonal cycles [3]. The Paris Climate Agreement seeks to keep global warming less than 2 ℃ by the end of this century via mitigating greenhouse gases [4]. Interestingly, methane (CH\u003csub\u003e4\u003c/sub\u003e) is approximately 25 times more potent than CO\u003csub\u003e2\u003c/sub\u003e as a greenhouse gas [5], but it can be effectively converted into syngas by partial oxidation of methane (POM), which lowers methane levels and generates a markedly high H\u003csub\u003e2\u003c/sub\u003e/CO ratio using molecular oxygen.\u003c/p\u003e\n\u003cp\u003eDue to its low cost, nickel-based catalysis for POM consistently attracts more attention than catalysts based on noble metals. The different pathways of POM across Ni-based catalysts are shown in Fig. 1. Under oxidizing gas O\u003csub\u003e2\u003c/sub\u003e and reducing gas H\u003csub\u003e2\u003c/sub\u003e, Ni and NiO are interchangeable \u0026nbsp;[6, 7]. Syngas is created via direct pathways where a mixture of CH\u003csub\u003e4\u003c/sub\u003e and O\u003csub\u003e2\u003c/sub\u003e is partially oxidized over metallic Ni. An pathways of syngas formation \u0026nbsp;is discussed via indirect pathway where \u0026ldquo;CH\u003csub\u003e4\u003c/sub\u003e and O\u003csub\u003e2\u003c/sub\u003e\u0026rdquo;\u003csub\u003e\u0026nbsp;\u003c/sub\u003eis catalyzed by NiO into \u0026ldquo;CO\u003csub\u003e2\u0026nbsp;\u003c/sub\u003eand H\u003csub\u003e2\u003c/sub\u003eO\u0026rdquo; (Total oxidation of CH\u003csub\u003e4\u003c/sub\u003e; TOM) and thereafter CO\u003csub\u003e2\u003c/sub\u003e or H\u003csub\u003e2\u003c/sub\u003eO oxidizes CH\u003csub\u003e4\u003c/sub\u003e into syngas \u0026nbsp;[8\u0026ndash;10]. Methane can serve as a valuable resource for hydrogen production by properly utilizing the catalyst and reaction conditions to reach the appropriate H\u003csub\u003e2\u003c/sub\u003e/CO ratio.\u003c/p\u003e\n\u003cp\u003eA proper metal oxide support gives a ground for fine dispersion of Ni and creating large number of active sites for POM reaction. Ni supported over basic oxides like MgO forms NiO-MgO solid solution, which is difficult to reduce and deactivate fast in POM reaction [9]. Ni supported over redox support like La\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and TiO\u003csub\u003e2\u003c/sub\u003e is prone to oxidation of Ni active sites [10\u0026ndash;12]. Compared to zirconia and alumina, the active metal Ni is less widely distributed over silica [13, 14]. Because of their quick phase transition at high temperatures, zirconia-based catalysts are likewise not advised for use as supports. Ni/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts work better at POM because they have more weak and medium Lewis acid sites [15]. Here, the active sites of metallic Ni are supposed to be stabilized by surface unsaturated pentahedral coordination Al\u003csup\u003e3+,\u003c/sup\u003e resulting in sinter resistance and coke resistance [16]. The ZSM-5 type zeolites are alumina-silicate populated with Br\u0026oslash;nsted sites rather than Lewis sites of alumina [15], and Ni/ZSM-5 performance towards POM was found to be better than Ni/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e. When Ce and Ni are combined, a Ni-CeO\u003csub\u003e2\u003c/sub\u003e interface is formed, which quickly supplies lattice oxygen for the oxidation of CH\u003csub\u003e4\u003c/sub\u003e and improves catalytic efficiency [17]. Different silica-alumina ratios and synthetic conditions can be used to adjust the pore models of molecular sieves, which are artificial zeolites [18]. A molecular sieve allows only small molecules to pass through as well, and its specific pore architecture stabilizes the active sites against high-temperature conditions. Molecular sieve support for Ni-based catalyst application could be a viable solution for POM-like reactions occurring between 500 \u0026nbsp;and 800\u0026nbsp;\u0026deg;C.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHerein, the CBV20A molecular sieve (SiO\u003csub\u003e2\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e = 20, surface area = 500 m\u003csup\u003e2\u003c/sup\u003e/g) was investigated for supporting the active sites \u0026ldquo;Ni (5wt.%)\u0026rdquo; for catalytic application towards POM. The catalyst of 5Ni/CBV20A was promoted with 1-3 wt.% ceria to boost oxidizing potential. The 5Ni/CBV20A and 5NixCe/CBV20A (x = 1-3 wt.%) catalysts were characterized by surface characterization techniques (like N\u003csub\u003e2\u003c/sub\u003e adsorption-desorption isotherms, temperature programmed reduction/oxidation), spectroscopic techniques (like X-ray diffraction, Infrared and Raman) and thermogravimetric analysis. The practical use of a ceria-promoted molecular sieve for Ni-based catalysis towards POM was demonstrated through the correlation between structural properties and catalytic performance.\u0026nbsp;\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cp\u003e2.1. Materials\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Ni(NO₃)₂\u0026middot;6H₂O (98%, Alfa Aesar), Ce(NO₃)₃\u0026middot;6H₂O (98%, Daiichi Kigenso Kagaku Kogyo Co. Ltd.), CBV20A (Zeolyst), and deionized water.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e2.2. Catalyst Preparation\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe incipient wetness impregnation method is applied in catalyst preparation. Ni (NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO solution (equivalent to 5 wt.% Ni) and Ce(NO₃)₃\u0026middot;6H₂O solution (equivalent to 1-3 wt.% Ce) are added in a beaker and stirred continuously while being heated. Further, 1 g CBV20A artificial molecular sieve is added to the solution and the solution is stirred continuously for 3 h under heating. The metal precursor solution is dispersed over the surface as well as inside the pores of the molecular sieves. The slurry is further dried at 120 \u003csup\u003eo\u003c/sup\u003eC for 3 h. The dried sample was calcined in air at 600 \u0026deg;C for 3 h. The target of calcination is to bring out metal oxide phases from the precursors\u0026apos; solution and products of their interaction with a support, as well as to remove the water molecules from the lattice. Up to 600 \u0026deg;C calcination temperature, the precursors give rise to both cerium oxide and nickel oxide, and all water molecules are removed from the lattice as well [19, 20]. The produced powdered catalysts are denoted as 5Ni/CBV20A and 5NixCe/CBV20A for convenience, with the Ni loading set at 5 weight percent and the Ce loading \u0026quot;x\u0026quot; varying between 1 and 3 weight percent. S1 and S2, which outline the catalyst characterization and evaluation test, are included in the additional file [21].\u003c/p\u003e"},{"header":"3. Results and Discussion","content":"\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Characterization Results and Discussion\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e display the surface area parameters and pore size distribution over 5Ni/CBV20A and 5NixCe/CBV20A (x\u0026thinsp;=\u0026thinsp;1\u0026ndash;3 wt.%) catalysts. The slit-type mesopores are confirmed in catalyst through type IV isotherm having H3 hysteresis loop. The pore size distribution plots reveal a monomodal distribution of pore in 3.72\u0026ndash;4 nm sizes range which is a typical mesopores range. Nonetheless, the average pore size is more wider (~\u0026thinsp;7.2 nm). Non-promoted catalyst attains maximum surface area (373 m\u003csup\u003e2\u003c/sup\u003e/g), and pore volume (0.130 cm\u003csup\u003e3\u003c/sup\u003e/g). In contrast, the 1 weight percent Ce-promoted 5Ni/CBV20A catalyst's surface area and pore volume significantly shrank. This suggests that ceria nanocrystallites may have blocked the pore structure. Unexpectedly, the surface area increased at 2 wt.% Ce, potentially due to improved dispersion of Ni species. It seems that 2 wt.% ceria addition induced finer dispersion of Ni over the CBV20A support. Following additional loading of ceria (3 wt.%) over 5Ni/CBV20A, the pore volume and surface area abruptly decreased to 0.124 cm\u003csup\u003e3\u003c/sup\u003e/g and 346 m\u003csup\u003e2\u003c/sup\u003e/g, respectively. It seems that the higher loadings of ceria did not induce Ni\u0026rsquo;s dispersion, although the ceria crystallites were readily deposited in the pores.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe BET surface area, pore volume, and average pore size of 5Ni/CBV20A and 5NixCe/CBV20A (x\u0026thinsp;=\u0026thinsp;1\u0026ndash;3 wt.%) catalysts.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSurface Area\u003c/p\u003e \u003cp\u003e(m\u003csup\u003e2\u003c/sup\u003e/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePores Volume (cm\u003csup\u003e3\u003c/sup\u003e/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAverage Size of Pores (nm)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5Ni/CBV20A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e373\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.130\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5Ni1Ce/ CBV20A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e351\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.128\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7.11\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5Ni2Ce/ CBV20A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e364.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.129\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7.21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5Ni3Ce/ CBV20A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e346.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.124\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7.16\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA display the X-ray diffraction of CBV20A, 5Ni/CBV20A, and 1\u0026ndash;3 wt.% ceria promoted 5Ni/CBV20A. Upon the addition of Ni over the molecular sieve (CBV20A), the intensity of diffraction patterns decreased readily, whereas the 5Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;NiO phase appeared markedly. The 5Ni/CBV20A shows the characteristic peaks for commercial mordenite at 6.6 ̊, 8.7 ̊, 9.8 ̊, 13.6 ̊, 14.6 ̊, 15.3 ̊, 19.7 ̊, 22.5 ̊, 23.2 ̊, 23.7 ̊, 25.8 ̊, 26.5 ̊, 27.8 ̊, 31 ̊, and 35.8 ̊ [22], and monoclinic 5Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;NiO phase (NiAl\u003csub\u003e10\u003c/sub\u003eO\u003csub\u003e16\u003c/sub\u003e phase) at 38 ̊ and 44.4 ̊ Bragg\u0026rsquo;s angle (JCPDS reference number 00-037-1292). XRD data revealed the close interaction of \u0026ldquo;NiO and Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026rdquo;. The intensity of the mordenite peaks increased when ceria was added up to 2 wt.% to the 5Ni/CBV20A. It suggests that when ceria is loaded, the mordenite framework is strengthened. The intensity of diffraction pattern for the distinctive mordenite peak decreased with further ceria loading (up to 3 wt.%). Over the 5Ni3Ce/CBV20A, the intensity of the crystalline peaks for the monoclinic 5Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;NiO phase consistently decreased. This indicates that ceria enhanced the dispersion of NiO species within the composite material.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eE displays the 5Ni/CBV20A and 5NixCe/CBV20A (x\u0026thinsp;=\u0026thinsp;1\u0026ndash;3 weight percent) catalysts' Raman vibration spectra. Raman vibrations of Si-O are clearly visible in the 5Ni/CBV20A catalyst at 283 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 403 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 511 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 856 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 928 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 1051 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and 1160 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. While Si/Si and Al/Al translational lattice modes are shown at 139 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The Raman vibration of Al-O is visible at 679 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Curiously, the Si-O or Al-O vibrational peaks decreased with the promotional addition of 1\u0026ndash;2 weight percent Ce, and their intensity was negligible at 3 weight percent ceria loading. It shows that when ceria is added, the polarisability of Si-O and Al-O bonds decreases. It is due to less distortion of electrons over Si-O and Al-O from their original positions. Strong Si-O (or Al-O) interactions or the development of a strong covalent bond between Si-O (or Al-O) are responsible for the low polarisability in silica and alumina [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eF displays the FTIR spectra of 5Ni/CBV20A and 5NixCe/CBV20A (x\u0026thinsp;=\u0026thinsp;1\u0026ndash;3 weight percent). The distinctive mordenite peaks at 460 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 565 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 800 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and 1100 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are visible in all catalysts [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. For bending and stretching hydroxyl, the vibration peaks are shown as a broad band at 3427 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and a sharp peak at 1630 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Shoulder peaks at 3625 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are also identified as proton-donating sites, such as Br\u0026oslash;nsted acid sites [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eG shows the TGA results for each catalyst. Due to water desorption, it exhibits constant weight loss up to 200\u0026ndash;300\u0026deg;C [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. There is a slight weight loss of 5.05 to 7.17 percent over 5Ni/CBV20A and 5NixCe/CBV20 (x\u0026thinsp;=\u0026thinsp;1\u0026ndash;3 weight percent) after 300\u0026deg;C.\u003c/p\u003e \u003cp\u003eThe reduction of 5Ni/CBV20A and 5NixCe/CBV20A (x\u0026thinsp;=\u0026thinsp;1\u0026ndash;3 weight percent) was performed using an H\u003csub\u003e2\u003c/sub\u003e-temperature program and shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003eA \u003cb\u003eand\u003c/b\u003e Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. It offers Ni and the support a special level of interaction. A non-promoted catalyst's reduction profile consists of a large peak at roughly 450\u0026deg;C and a diffuse peak at roughly 322\u0026deg;C. SiO\u003csub\u003e4\u003c/sub\u003e tetrahedra and AlO\u003csub\u003e4\u003c/sub\u003e tetrahedra are building block of crystalline framework of alumino-silicates where silica is tetravalent, and alumina is trivalent. Successive substitution of tetravalent silicon by a trivalent aluminum atom generates an extra anionic charge. To achieve charge neutrality, cationic species (like Ni\u003csup\u003e2+\u003c/sup\u003e) compensate with the resulting negative lattice charge [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Therefore, the reduction of Ni\u003csup\u003e2+\u003c/sup\u003e (or NiO) isolated within the charge compensation sites is responsible for the low-temperature reduction (322\u0026deg;C). One could refer to this NiO-support interaction as a moderate one. NiO is deposited over the molecular sieve at a location encircled by different cages of the mordenite-based molecular sieve, which strengthens the metal-support interaction. A comparatively stronger metal-support interaction of NiO is indicated by the reduction peak at higher temperature (450 \u003csup\u003eo\u003c/sup\u003eC). Remarkably, after addition of 1 wt. % ceria over Ni-supported molecular sieve, the low-temperature reduction peak is intensified while the overall H\u003csub\u003e2\u003c/sub\u003e consumption stays the same (15 cm\u003csup\u003e3\u003c/sup\u003e/g). It suggests that, compared to a non-promoted catalyst, the inclusion of ceria causes generation of more reducible NiO at charge compensation sites of CBV20A. The H\u003csub\u003e2\u003c/sub\u003e consumption increases significantly (19 cm\u003csup\u003e3\u003c/sup\u003e/g) when 2 wt % ceria is loaded on 5Ni/CBV20A. Additionally, the reduction peak at low-temperature intensifies more than the reduction peak at high-temperature. It shows that more reducible NiO species are being produced charge compensation sites of CBV20A. However, the strength of the high-temperature reduction peak is amplified, and the overall H\u003csub\u003e2\u003c/sub\u003e consumption reaches its maximum (20.9 cm\u003csup\u003e3\u003c/sup\u003e/g) with the highest loading of ceria (3 wt.%). For ceria-based catalysts, reducible surface capping oxygen has also been reported to exhibit a reduction peak at around 400\u0026ndash;500\u0026deg;C [\u003cspan additionalcitationids=\"CR34\" citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Therefore, the development of the reduction peak at roughly 450\u0026deg;C could be the result of both the reduction of reducible surface capping oxygen and the combined contribution of reducible NiO under strong metal-support interaction.\u003c/p\u003e \u003cp\u003eThe H\u003csub\u003e2\u003c/sub\u003e-TPR of the new catalyst is typically used to characterize a catalyst's reducibility profile. O\u003csub\u003e2\u003c/sub\u003e is the oxidant in POM, though, and it can oxidize both metallic \"Ni\" into NiO and the carbon deposit into syngas [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Consequently, Ni's active sites become inactive. The complete oxidation of methane is catalyzed by NiO [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. H\u003csub\u003e2\u003c/sub\u003e gas is also produced during the DRM reaction (as a component of syngas), which aids in preserving Ni's metallic phase once more. Overall, the catalyst reduction behavior may be altered by sequential treatment of oxidizing gas (O\u003csub\u003e2\u003c/sub\u003e) and reducing gas (H\u003csub\u003e2\u003c/sub\u003e). To understand the reduction-oxidation-reduction profile H\u003csub\u003e2\u003c/sub\u003eTPR-O\u003csub\u003e2\u003c/sub\u003eTPO-H\u003csub\u003e2\u003c/sub\u003eTPR cyclic experiment is conducted over 5Ni/CBV20A and a 2-weight percent ceria promoted 5Ni/CBV20A catalyst (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003eB-C). Following a series of reduction-oxidation-reduction treatments, the 5Ni/CBV20A catalysts' reduction profiles are enhanced and expanded to higher temperatures (600\u0026deg;C). The disappearance of the reduction peak in low-temperature region and appearance of reduction peak in high-temperature region (about 600\u0026deg;C) during the last H\u003csub\u003e2\u003c/sub\u003e-TPR (in the cyclic experiment) can be used to specify the reduction profile of the 5Ni2Ce/CBV20A catalyst in the co-presence of oxygen and hydrogen. It shows that the reductive and oxidative gas stream (during POM) induce stronger metal-support interaction at the expense of weak metal-support interaction over the ceria-promoted 5Ni/CBV20A catalyst.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003eD shows the results of CO\u003csub\u003e2\u003c/sub\u003e temperature-programmed desorption (TPD). The acidic gas CO₂ is adsorbed over the basic sites of catalyst. The surface hydroxyl groups generate weak basic sites which interacts with CO\u003csub\u003e2\u003c/sub\u003e. These interacted-CO\u003csub\u003e2\u003c/sub\u003e is desorbed at lower temperatures (\u0026lt;\u0026thinsp;200\u0026deg;C) in CO\u003csub\u003e2\u003c/sub\u003e-TPD. Similarly, basic surface oxide anions contribute to the moderate strength basic site which interact CO\u003csub\u003e2\u003c/sub\u003e with stronger strength. These interacted-CO\u003csub\u003e2\u003c/sub\u003e is desorbed in the intermediate temperature range (~\u0026thinsp;200\u0026ndash;400\u0026deg;C) [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. The decomposition of carbonates is responsible for the CO\u003csub\u003e2\u003c/sub\u003e desorption peak above 400\u0026deg;C [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. These basic sites can be referred to as strong basic sites. Interestingly, the non-promoted catalyst (5Ni/CBV20A) has the largest population of moderate-strength basic sites but a diffuse population of strong basic sites. The population for moderate-strength basic sites is comparatively decreased as ceria loading increases over 5Ni/CBV20A. Decomposable surface carbonate's peak intensity rises when 1 weight percent Ce is added over 5Ni/CBV20A. According to reports in the literature, ceria also interacts with CO\u003csub\u003e2\u003c/sub\u003e and forms surface carbonate and surface carboxylates quickly [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. It should be noted that the apex of strong basic sites is absent at 2 weight percent ceria loading over 5Ni/CBV10A. Again, in 3 wt.% ceria, such strong basic sites are observed with relatively lower intensity (than 5Ni1Ce/CBV20A). Therefore, it may be concluded that at 2 wt.% of ceria-promoted 5Ni/CBV20 catalyst, either no surface carbonate forms or a stable, non-decomposable surface carbonate forms. Ce\u003csub\u003e2\u003c/sub\u003e(CO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e has been reported in the literature as a stable structure; nonetheless, it can decompose at 700 \u0026deg;C [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. This absence of a CO₂ desorption peak between 500 and 900\u0026deg;C suggests the 5Ni2Ce/CBV20A catalyst lacks decomposable surface carbonate species.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe total quantity of H\u003csub\u003e2\u003c/sub\u003e consumption by the catalyst during the H\u003csub\u003e2\u003c/sub\u003e-TPR experiment.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eName of Catalyst\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTotal H\u003csub\u003e2\u003c/sub\u003e Quantity Used\u003c/p\u003e \u003cp\u003e(cm\u0026sup3;/g STP)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5Ni/CBV20A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e14.97\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5Ni1Ce/CBV20A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e15.00\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5Ni2Ce/CBV20A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e19.08\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5Ni3Ce/CBV20A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20.90\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003e displays the particle size distribution and transmission electron microscopy images of fresh and spent 5Ni/CBV20A and 5Ni2Ce/CBV20A. The particle size of fresh 5Ni/CBV20A and 5Ni2Ce/CBV20A catalysts was 8.2 nm and 9.17 nm, respectively. Over spent 5Ni/CBV20A and 5Ni2Ce/CBV20A catalysts, particle sizes increased to 9.2 and 10.5 nm, respectively. The particle size increased during the POM reaction over both 5Ni/CBV20A and 5Ni2Ce/CBV20A catalysts. The increase in particle size during the POM process was attributed to the thermal sintering of Ni metal under high-temperature reaction conditions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e\u003cem\u003e3.2.\u003c/em\u003e Results of Catalytic Activity and Discussion\u003c/h2\u003e \u003cp\u003eThe CBV20A, a mordenite-type molecular sieve, has a silica-alumina ratio of 20 and a large surface area of 500 m\u003csup\u003e2\u003c/sup\u003e/g. It is used to support 5 wt.% Ni. Additionally, 1\u0026ndash;3 wt.% ceria is used as a promoter over 5Ni/CBV20A to modify the reducibility, basicity, and crystallinity. The formation of 5Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e.NiO phase over each catalyst shows the intimate interaction of NiO over an alumina-silicates framework of molecular sieve. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e6\u003c/span\u003e displays the catalytic activity for POM over 5Ni/CBV20A and 1\u0026ndash;3 wt.% ceria-promoted 5Ni/CBV20A catalysts. The catalytic system exhibited an H₂/CO ratio ranging from 2.4\u0026ndash;2.6 H\u003csub\u003e2\u003c/sub\u003e/CO ratio, \u0026gt;\u0026thinsp;40% H\u003csub\u003e2\u003c/sub\u003e yield, \u0026gt;\u0026thinsp;20% CO\u003csub\u003e2\u003c/sub\u003e production, and \u0026gt;\u0026thinsp;60% CH\u003csub\u003e4\u003c/sub\u003e conversion. The stoichiometric ratio of H\u003csub\u003e2\u003c/sub\u003e to CO in a direct POM reaction should be 2, but in this case, it is greater than 2. This suggests that the direct POM response routes are not the only pathways. Once more, a yield of more than 20% CO\u003csub\u003e2\u003c/sub\u003e across all catalyst systems suggests that complete oxidation of CH\u003csub\u003e4\u003c/sub\u003e by O\u003csub\u003e2\u003c/sub\u003e occurs easily. While metallic Ni is a catalytically active site for DRM and SRM, NiO has been shown to catalyse TOM. Therefore, there is a chance that CH\u003csub\u003e4\u003c/sub\u003e will once more interact with the total oxidation products (CO\u003csub\u003e2\u003c/sub\u003e \u0026amp; H\u003csub\u003e2\u003c/sub\u003eO). Indirect POM pathways may proceed via sequences such as TOM followed by DRM or SRM.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e5Ni/CBV20A catalyst acquired high crystallinity, the largest surface area and pore volume where active sites originate. NiO is interacted with CBV20A support through strong and moderate interaction. After reduction, these interacted-NiO species generates metallic Ni as active sites. Remarkably, the total concentration of active sites rose, and the metal-support interaction improved under O\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003e gases (verified by H\u003csub\u003e2\u003c/sub\u003eTPR-O\u003csub\u003e2\u003c/sub\u003eTPO-H\u003csub\u003e2\u003c/sub\u003eTPR cyclic experiment). The 5Ni/CBV20A catalyst attains the highest concentration of moderate-strength basic sites. The basic sites are needed for the interaction of CO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003eO (the product of TOM) and the re-engagement of these gases as oxidants for methane oxidation under indirect pathways. Overall, 5Ni/CBV20A shows 63% CH\u003csub\u003e4\u003c/sub\u003e conversion and 40% H\u003csub\u003e2\u003c/sub\u003e yield with a 2.6 H\u003csub\u003e2\u003c/sub\u003e/CO ratio at the end of 230 minutes.\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eAfter adding 1 wt.% ceria over 5Ni/CBV20A, the covalent bond between Si-O and Al-O becomes stronger (verified by Raman), the crystallinity of mordenite framework increased relatively, the strong basic sites\u0026rsquo; concentration was intensified, the surface area and pore volume decreased and the total amount of active sites remained constant than the non-promoted catalyst. Interestingly, CH\u003csub\u003e4\u003c/sub\u003e conversion and CO\u003csub\u003e2\u003c/sub\u003e yield over 5Ni1Ce/CBV20A remain similar to 5Ni/CBV20A catalyst. Since the total concentration of active sites \u0026ldquo;Ni\u0026rdquo; remains the same, the ability of 5Ni1Ce/CBV20A to activate C\u0026ndash;H bonds in CH₄ remains comparable to that of the non-promoted catalyst. However, the concentration of active sites derived from \u0026ldquo;NiO under moderate interaction\u0026rdquo; is growing, as well as a catalyst is also populated by strong basic sites. In comparison to the 5Ni/CBV20A catalyst, the H\u003csub\u003e2\u003c/sub\u003e and CO yields over 5Ni1Ce/CBV20A catalyst are improved by 50\u0026ndash;60%. The crystallinity of the mordenite framework increases comparatively when 2 weight percent ceria loading is applied over 5Ni/CBV20A. Furthermore, compared to previous ceria loadings, the fine dispersion at 2 wt.% ceria loading produces an increased surface area and pore volume. It is filled with basic sites of moderate strength. The population of \"NiO under moderate interaction\" and the total population of active sites are highest over 5Ni2Ce/CBV20A. The metal-support interaction of NiO is strengthened in the presence of reducing gas (H\u003csub\u003e2\u003c/sub\u003e) and oxidizing gas (O\u003csub\u003e2\u003c/sub\u003e), which increases the concentration of stable active sites for the POM reaction. Figure\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e depicts the direct and indirect paths of the POM reaction over 5Ni2Ce/CBV20A. The partial oxidation of methane by O\u003csub\u003e2\u003c/sub\u003e (POM routes) is catalyzed by the concentration of metallic Ni, whereas the complete oxidation of CH\u003csub\u003e4\u003c/sub\u003e by O\u003csub\u003e2\u003c/sub\u003e (TOM) is catalyzed by the concentration of NiO throughout the reaction. Under indirect pathways of POM, CO\u003csub\u003e2\u003c/sub\u003e oxidizes CH\u003csub\u003e4\u003c/sub\u003e into syngas by the DRM reaction over the metallic Ni, and H\u003csub\u003e2\u003c/sub\u003eO oxidizes CH\u003csub\u003e4\u003c/sub\u003e into syngas over metallic Ni through the SRM process. A ceria loading of 2 wt.% was found to be optimal, and it achieves about 65% CH\u003csub\u003e4\u003c/sub\u003e conversion and 62% H\u003csub\u003e2\u003c/sub\u003e yield with a 2.5 H\u003csub\u003e2\u003c/sub\u003e/CO ratio at the end of 230 minutes.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eOver 5Ni3Ce/CBV20A, the crystallinity of the mordenite framework decreased, and the catalysts\u0026rsquo; surface area and pore volumes decreased significantly. Still, it has the highest concentration of reducible species, including the reducible ceria. It has an adequate concentration of strong basic sites/surface carbonates. The H\u003csub\u003e2\u003c/sub\u003e yield drops to 58% over 5Ni3Ce/CBV20A, whereas the CO\u003csub\u003e2\u003c/sub\u003e yield reaches its maximum value of 25%. While metallic Ni catalyzes the direct POM, DRM, and SRM reactions, NiO catalyzes the complete oxidation of CH\u003csub\u003e4\u003c/sub\u003e into CO\u003csub\u003e2\u003c/sub\u003e. By oxidizing the Ni to NiO, the excess ceria may promote total oxidation and inhibit the DRM/SRM process in indirect POM route. Notably, CH₄ conversion over 5Ni3Ce/CBV20A is even lower than that of the non-promoted catalyst, suggesting excessive ceria loading may block active sites, limiting catalytic performance [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe current catalyst system's activity is contrasted with that of the POM catalyst systems that have been published (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). LaNiO\u003csub\u003e3\u003c/sub\u003e's H\u003csub\u003e2\u003c/sub\u003e-yield and H\u003csub\u003e2\u003c/sub\u003e/CO ratio are found to be more competitive than those of the current catalyst, 5Ni2Ce/CBV20A, under comparable conditions. However, POM operates at a higher temperature (700\u0026deg;C) than the LaNiO\u003csub\u003e3\u003c/sub\u003e catalyst, and it requires five times more catalyst mass for the reaction than the existing catalytic system. Overall, at 600\u0026deg;C reaction temperature and 100 mg catalyst amount, the present catalyst, 5Ni2Ce/CBV20A, outperforms than others.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe comparison of catalytic activity of the catalyst system with reported catalyst system towards partial oxidation of methane reaction. .\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"13\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eNo.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCatalyst\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eRT\u003c/p\u003e \u003cp\u003e(\u003csup\u003eo\u003c/sup\u003eC)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eWM\u003c/p\u003e \u003cp\u003e(wt.%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCW\u003c/p\u003e \u003cp\u003e(mg)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c8\" namest=\"c6\"\u003e \u003cp\u003eFlow rate\u003c/p\u003e \u003cp\u003e(cm\u003csup\u003e3\u003c/sup\u003e/min)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTOS\u003c/p\u003e \u003cp\u003e(Min)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\varvec{X}}_{{\\varvec{C}\\varvec{H}}_{4}}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003e(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{\\varvec{Y}}_{{\\varvec{H}}_{2}}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003e(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003e /CO\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c13\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eRef.\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eCO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eInert\u003c/p\u003e \u003cp\u003egas\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5Ni/30TiO\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;ZrO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e240\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5Ni2.5Sr/30TiO\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;ZrO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e240\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e3.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMesoporous-LaNiO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e700\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e6000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBulk-LaNiO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e700\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e6000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e- ZrO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e3000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi/MgO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e750\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e210\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e3.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5Ni/La\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-BFA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e850\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e300\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e510\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10Ni/La\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-BFA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e850\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e300\u003c/p\u003e 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align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e3000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e 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colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e27.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi/ZrO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e650\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e3000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi/TiZr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e300\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e4.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi2Cs/TiZr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e300\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e3.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi2Ce/TiZr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e300\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e3.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNi2Sr/TiZr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e 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align=\"left\" colname=\"c1\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5Ni/SAPO-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e240\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e41.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e3.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5Ni\u0026thinsp;\u003cb\u003e+\u003c/b\u003e\u0026thinsp;1Ce/SAPO-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e240\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e43.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e3.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5Ni\u0026thinsp;\u003cb\u003e+\u003c/b\u003e\u0026thinsp;1Sr/SAPO-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e240\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e48.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e41.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e3.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5Ni\u0026thinsp;\u003cb\u003e+\u003c/b\u003e\u0026thinsp;1Cu /SAPO-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e240\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e49.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e4.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5Ni/CBV20A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e230\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCurrent Study\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5Ni2Ce/CBV20A\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e600\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e230\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e2.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eBFA: Biomass Fly Ash, RT\u0026thinsp;=\u0026thinsp;Reaction Temperature, WM\u0026thinsp;=\u0026thinsp;weight % of active metal, * = Ni amount is shown in millimole, CW\u0026thinsp;=\u0026thinsp;Catalyst weight take for a reaction, TOS\u0026thinsp;=\u0026thinsp;Time on stream, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{X}_{{CH}_{4}}\\)\u003c/span\u003e\u003c/span\u003e \u003cem\u003e=\u003c/em\u003e CH\u003csub\u003e4\u003c/sub\u003e conversion (%), \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{Y}_{{H}_{2}}\\)\u003c/span\u003e\u003c/span\u003e = H\u003csub\u003e2\u003c/sub\u003e yield (%).\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThe mordenite-based molecular sieve CBV20A (SiO₂/Al₂O₃ = 20) effectively anchors NiO, with its cage-like structure and charge-compensation sites contributing to stabilization. The unique 5Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e.NiO phase over the catalyst confirms the strong interaction of NiO with the alumina component of the molecular sieve. Exposure to reducing and oxidizing gases during POM increases the concentration of reducible species and improves the metal-support interaction. Moderate-strength basic sites found in 5Ni/CBV20A may facilitate interaction with CO₂ and H₂O (the development of total oxidation of methane) for indirect CH\u003csub\u003e4\u003c/sub\u003e oxidation. After 230 minutes, it yields 40% H\u003csub\u003e2\u003c/sub\u003e and 63% CH\u003csub\u003e4\u003c/sub\u003e conversion with a 2.6 H\u003csub\u003e2\u003c/sub\u003e/CO ratio. By increasing the covalent connection between Si-O and Al-O and enhancing the population of active sites (obtained from NiO under moderate interaction), a promotional addition of 1 wt.% ceria over 5Ni/CBV20A results in a 50–60% increase in H\u003csub\u003e2\u003c/sub\u003e yield without changing the H\u003csub\u003e2\u003c/sub\u003e/CO ratio. The overall number of active sites increases, and the population of active sites resulting from the \"NiO under moderate interaction\" reaches its peak at 2 weight percent ceria loading. During POM, the metal-support interaction of NiO is expanding under O\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003e gases. Without changing the H\u003csub\u003e2\u003c/sub\u003e/CO ratio under direct and indirect pathways for POM, 5Ni2Ce/CBV20A achieves a maximum of 65% CH\u003csub\u003e4\u003c/sub\u003e conversion and 62% H\u003csub\u003e2\u003c/sub\u003e yield (after 230 minutes). The significant decrease in surface properties and the possible oxidation of active sites by ceria are the principal reason of inferior catalytic activity towards POM and highest CO\u003csub\u003e2\u003c/sub\u003e-yield over 5Ni3Ce/CBV20A. The application of the ceria-promoted Ni-containing molecular sieve as a possible catalyst system for POM is demonstrated by the achievement of high CH\u003csub\u003e4\u003c/sub\u003e conversion (65%) and high H\u003csub\u003e2\u003c/sub\u003e yield (62%), with a notably high H₂/CO ratio of 2.6.\u003c/p\u003e"},{"header":"Abbreviation","content":"\u003cp\u003e\u003cstrong\u003ePOM:\u0026nbsp;\u003c/strong\u003ePartial oxidation of methane\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTOM:\u0026nbsp;\u003c/strong\u003eTotal oxidation of methane\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDRM:\u0026nbsp;\u003c/strong\u003eDry Reforming of Methane\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSRM:\u0026nbsp;\u003c/strong\u003eSteem Reforming of Methane\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTPR:\u0026nbsp;\u003c/strong\u003eTemperature Programmed Reduction\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTPO:\u0026nbsp;\u003c/strong\u003eTemperature Programmed Oxidation\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTOS:\u003c/strong\u003e Time on Stream\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical and Consent to Participate:\u0026nbsp;\u003c/strong\u003eIn this research article, all experimental procedures, including the catalyst Preparation, catalyst Activity Test, and catalyst characterization, complied with laboratory safety protocols and institutional guidelines. No ethical approval was required for this work.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for Publication:\u0026nbsp;\u003c/strong\u003eAll authors have reviewed the final version of the manuscript and given their consent for its submission for publication. The content of this paper, including Abstract, Experimental data, Figures, Conclusions, and\u0026nbsp;Supplementary Materials, is\u0026nbsp;original and has not been published elsewhere.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests:\u0026nbsp;\u003c/strong\u003eThe authors declare no competing interests.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAbdulaziz Al-Anazi:\u0026nbsp;\u003c/strong\u003eConceptualization, Investigation, Writing.\u003cstrong\u003e\u0026nbsp;Amal BaQais:\u003c/strong\u003e Resources, Data curation.\u003cstrong\u003e\u0026nbsp;Kenit Acharya:\u0026nbsp;\u003c/strong\u003eWriting,Data curation, Investigation, Software.\u0026nbsp;\u003cstrong\u003eOmer Bellahwel :\u003c/strong\u003e Resources, Formal analysis, Data curation.\u003cstrong\u003e\u0026nbsp;Ahmed I. Osman:\u0026nbsp;\u003c/strong\u003eConceptualization, Investigation, Writing,\u0026nbsp;Supervision, methodology, visualization.\u003cstrong\u003e\u0026nbsp;Ahmed A. Ibrahim:\u0026nbsp;\u003c/strong\u003eData curation, Visualization, Software. Methodology, Formal analysis.\u0026nbsp;\u003cstrong\u003eFekri Abdulraqeb Ahmed Ali\u003c/strong\u003e\u003cstrong\u003e:\u0026nbsp;\u003c/strong\u003eReview,Methodology, Formal analysis. \u0026nbsp;\u003cstrong\u003e\u0026nbsp;Salwa B. Alreshaidan\u003c/strong\u003e\u003cstrong\u003e:\u0026nbsp;\u003c/strong\u003eSoftware, formal analysis, Resources.\u003cstrong\u003e\u0026nbsp;Ahmed E. Abasaeed:\u0026nbsp;\u003c/strong\u003eInvestigation, supervision, methodology. \u003cstrong\u003eChangseok Han\u003c/strong\u003e\u003cstrong\u003e:\u003c/strong\u003e Data curation, Validation, Software.\u0026nbsp;\u0026nbsp;\u003cstrong\u003eRawesh Kumar:\u0026nbsp;\u003c/strong\u003eData curation, Writing\u0026nbsp;–\u0026nbsp;review\u0026nbsp;\u0026amp;\u0026nbsp;editing.\u0026nbsp;\u003cstrong\u003eAhmed S. Al-Fatesh:\u003c/strong\u003e Data curation, Methodology, Writing, reviewing \u0026amp; editing, Funding acquisition, Project Administration.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e Researchers Supporting Project number (RSP2024R368), King Saud University.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e: Data are contained within the article and Supplementary Materials\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments:\u003c/strong\u003e The authors would like to extend their sincere appreciation to the\u0026nbsp;Princess Nourah bint Abdulrahman University Researchers Supporting Project number (PNURSP2025R230), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia.\u0026nbsp;Also, the authors would like to express their Wholehearted gratitude to King Saud University's Researchers for Supporting Project No. (RSPD2025R779).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eSong F, Zhang GJ, Ramanathan V, Leung LR (2022) Trends in surface equivalent potential temperature: A more comprehensive metric for global warming and weather extremes. 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Catalysis letters 78:215\u0026ndash;222\u003c/li\u003e\n \u003cli\u003edos Anjos WL, Morales SAV, Oliveira NMB, Valen\u0026ccedil;a GP (2021) Effect of silica/alumina ratio and structure-directing agent on the physical and chemical properties of SAPO-34. Journal of Sol-Gel Science and Technology 100:466\u0026ndash;476\u003c/li\u003e\n \u003cli\u003eBrockner W, Ehrhardt C, Gjikaj M (2007) Thermal decomposition of nickel nitrate hexahydrate, Ni (NO3) 2\u0026middot; 6H2O, in comparison to Co (NO3) 2\u0026middot; 6H2O and Ca (NO3) 2\u0026middot; 4H2O. Thermochimica Acta 456:64\u0026ndash;68\u003c/li\u003e\n \u003cli\u003eVratny F, Kern S, Gugliotta F (1961) The thermal decomposition of cerium (III) nitrate hydrate. Journal of Inorganic and Nuclear Chemistry 17:281\u0026ndash;285\u003c/li\u003e\n \u003cli\u003eJeangros Q, Hansen TW, Wagner JB, et al (2013) Reduction of nickel oxide particles by hydrogen studied in an environmental TEM. 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Catalysts 14:316\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Molecular sieve, Syngas, Zeolite, Ce promoter, POM, Hydrogen yield","lastPublishedDoi":"10.21203/rs.3.rs-6680604/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6680604/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMethane is one of the potent greenhouse gas which contributes to global warming deadly. Its emission cannot be stopped as it comes from various natural wetlands and anaerobic decomposition processes. Methane can be partially oxidized with a Ni-stabilized CBV20A molecular sieve (SiO\u003csub\u003e2\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e = 20) to produce hydrogen-rich syngas. The Ni catalyst is located at charge compensation sites and inside the molecular sieve's pores. The catalysts are characterized by X-ray diffraction, surface area \u0026amp; porosity, FTIR, Raman spectroscopy, thermogravimetry analysis, transmission electron microscopy, and temperature programmed reduction/desorption/oxidation techniques. It was revealed that 2 wt.% ceria addition over 5Ni/CBV20A induced higher surface area and total active sites than 1 wt.% ceria promoted 5Ni/CBV20A. Over 5Ni2Ce/CBV20A, the concentration of active sites obtained from \"NiO under moderate interaction\" is at its peak. The metal-support interaction is further enhanced by the periodic exposure of hydrogen and oxygen during POM. 5Ni2Ce/CBV20A exhibits 2.5 H\u003csub\u003e2\u003c/sub\u003e/CO, 65% H\u003csub\u003e2\u003c/sub\u003e yield, and 65% CH\u003csub\u003e4\u003c/sub\u003e methane conversion. High catalytic activity and the generation of hydrogen-rich syngas demonstrate the potential of Ni-based catalysts supported on a molecular sieve with a Ce promoter for POM.\u003c/p\u003e","manuscriptTitle":"Optimizing Ceria Promotion in Ni-Based Molecular Sieve Catalysts for Enhanced Hydrogen Production via Methane Partial Oxidation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-21 08:44:04","doi":"10.21203/rs.3.rs-6680604/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"171f1706-fd59-420e-b5fc-3eae06a7722e","owner":[],"postedDate":"May 21st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-06-06T10:23:47+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-21 08:44:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6680604","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6680604","identity":"rs-6680604","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}