Structural effect of Ni/SBA-15 by Zr promoter for H2 production via methane dry reforming

5 wt% of Ni/SBA-15 supported with numerous Zr loading (1–7 wt%) were produced using sol-gel technique at 60 °C. The influence of Zr promoter on the physiochemical properties of Ni/SBA-15 catalysts for methane dry reforming were examined in a fixed-bed reactor at 800 °C. Analytical characterizations including XRD, BET, FTIR, N₂ adsorption desorption, TEM and TGA were conducted to study the physiochemical properties of Zr/Ni/SBA-15 catalysts for the sake of identification of the amount of coke deposition formed on the spent catalyst. Increasing the amount of Zr loading from 1 to 7 wt% supported on Ni/SBA-15 reduced the catalyst's surface area as was proven from the physiochemical properties of Zr/Ni/SBA-15 catalyst. The catalytic activity test revealed that the optimum Zr loading was 1 wt% at which CH₄ and CO₂ conversions were 87.07% and 4.01%, meanwhile H₂:CO ratios was 0.42. This result was owing to the existence of the Zr species in promoting a good dispersion of Nickel (Ni) active sites on the catalyst surface as affirmed from XRD and FTIR results. The latest discovery indicates that promotion of 1 wt% Zr onto Ni/SBA-15 can prompt excellent catalytic performance in CRM.     

Hydrogen production via CO2 reforming of CH4 over low-cost Ni/SBA-15 from silica-rich palm oil fuel ash (POFA) waste

H₂ was produced via CO₂ reforming of CH₄ (CRM) using low-cost Ni/SBA-15 synthesized from palm oil fuel ash (POFA) waste as silica precursor. A series of Ni/SBA-15 were synthesized by employing different Na₂SiO₃-POFA/P123 mass ratios (2.0, 2.9 and 4.0) and were compared with Ni/SBA-15 prepared from commercial Na₂SiO₃ (Ni/SBA-15(Comm.)). Na₂SiO₃-POFA/P123 = 2.9 was found to be the optimal synthesis ratio, which produces a well-defined hexagonal framework, smaller NiO particles, stronger Ni-support interaction, homogeneous metal distribution and higher amount of basic sites. The catalytic performance complied with the trend of Ni/SBA-15(R4.0) < Ni/SBA-15(R2.0) < Ni/SBA-15(R2.9) ≈ Ni/SBA-15(Comm.), indicating the excellent catalytic activity of Ni/SBA-15(R2.9) (H₂ selectivity = 87.6%). The favorable physicochemical properties of Ni/SBA-15(R2.9) ameliorated the active Ni metals stabilization over SBA-15 and boosted the catalyst's virtues towards an outstanding catalytic performance. Hence, it is affirmed that POFA with an optimal Na₂SiO₃-POFA/P123 ratio of 2.9 can be served as silica substitution of Ni/SBA-15 for efficient H₂ production via CRM.     

Influence of impregnation assisted methods of Ni/SBA-15 for production of hydrogen via dry reforming of methane

SBA-15 support was successfully synthesized using extracted silica from palm oil fuel ash waste (POFA). Four types of Ni/SBA-15 catalysts were prepared via the ordinary impregnation technique (Ni/SBA-15(IM)) and assisted impregnation techniques including rotary evaporator (Ni/SBA-15(RE)), shaker (Ni/SBA-15(SH)) and ultrasonic (Ni/SBA-15(US)). The attributes of the Ni/SBA-15 were characterized using XRD, BET, FTIR, XPS, TEM, CO₂-TPD and TGA. The performance and stability of Ni/SBA-15 catalysts for up to 24 h were determined using a stainless steel fixed-bed reactor setup at 800 °C. The results in a descending order were ultrasonic (US) > ordinary impregnation (IM) > shaker (SH) > rotary evaporator (RE). The highest catalytic performance was achieved by Ni/SBA-15(US) owing to the location of Ni species inside the SBA-15 micelles, stronger Ni–O–Si interaction, and higher catalyst basicity. Lowest formation of graphite carbon on Ni/SBA-15(US) was correlated to the good dispersion of smaller Ni particles that were able to suppress the coke formation. The ultrasonic irradiation provided a cavitation effect which was able to destroy the soft agglomeration of Ni particles for better dispersion compared to IM, RE, and SH. This study provides an alternative in preparing better properties of catalyst to enhance the CO₂ reforming of CH₄ (CRM) in terms of activity and stability.     

Optimal Ni loading towards efficient CH4 production from H2 and CO2 over Ni supported onto fibrous SBA-15

The transformation of SBA-15 into fibrous type SBA-15 (F-SBA-15) as well as the influence of Ni loadings (1, 3, 5, and 10 wt%) towards an efficient CH₄ production from H₂ and CO₂ were explored. The synthesized catalysts were characterized using XRD, BET, ICP-MS, FTIR, FESEM-EDX, TEM, and in-situ FTIR adsorbed pyrrole. Increasing Ni loadings onto F-SBA-15 support promoted excellent performance towards CO₂ methanation. The efficacy in CO₂ methanation over Ni/F-SBA-15 increased with a sequence of 1%Ni/F-SBA-15 < 3%Ni/F-SBA-15 < 5%Ni/F-SBA-15 ≈ 10%Ni/F-SBA-15, indicating the superior performance and stability of 5%Ni/F-SBA-15. The increasing trend was due to the fibrous morphology of support which enhanced the quantity of SiONi bond, triggered better Ni dispersion, strengthen metal-support interaction, and increased the basicity. However, higher Ni loadings (10 wt%) onto F-SBA-15 slightly declined the performance and stability of CO₂ methanation due to the limited spaces for substitution of Ni species with the silanol groups of F-SBA-15 upon the bulk Ni phase, poorer Ni dispersion, weaker metal-support interaction, and lower basicity. The new finding of combination between fibrous SBA-15 (F-SBA-15) with an optimum Ni loading contributed towards an outstanding performance and thus could be applied in various applications.     

Promising hydrothermal technique for efficient CO2 methanation over Ni/SBA-15

The comparative study of different hydrothermal treatment techniques (Reflux (R) and Teflon (T)) and without hydrothermal technique (W) towards efficient CO₂ methanation over Ni/SBA-15 was discussed. X-ray diffraction (XRD), inductive coupling plasma-atomic emission spectroscopy (ICP-AES), N₂ adsorption-desorption isotherms (BET), Fourier transform infrared (FTIR) spectroscopy, UV-vis diffuse reflectance spectroscopy (UV-Vis DRS), scanning electron microscope – energy dispersion x-ray (SEM-EDX), and transmission electron microscope (TEM) analysis showed that Ni/SBA-15(R) possessed fascinating catalytic properties owing to the highest surface area (814 m²/g) and pore diameter (5.49 nm) of SBA-15(R), finest metal particles (17.92 nm), strongest metal-support interaction and highest concentration of basic sites. The efficacy of Ni/SBA-15 towards CO₂ methanation was descending as Ni/SBA-15(R) > Ni/SBA-15(T) > Ni/SBA-15(W), implying the outstanding performance of Ni/SBA-15(R) which in parallel with the characterization results. The lowest performance of Ni/SBA-15(W) was due to the poorest properties of support; lowest surface area and pore diameter, largest Ni sizes, weakest metal-support interaction and lowest concentration of basic sites. This study successfully developed fascinating Ni/SBA-15 through the reflux hydrothermal treatment technique for CO₂ methanation.     

Supporting high-loading Ni on SBA-15 as highly active and durable catalyst for ammonia decomposition reaction

Although supported Ni is generally considered the most active non-noble metal catalyst for decomposing NH₃ to produce CO_x-free H₂, its activity is not sufficient. Herein, supporting high-loading Ni on SBA-15 is explored to alleviate the low intrinsic activity issue of Ni. SBA-15 supports with tunable textual properties are synthesized to support Ni catalyst for NH₃ decomposition. Characterization shows that Ni catalyst with a loading close to 40 wt% supported on SBA-15 with the largest specific surface area (Ni/SBA-15-80) exhibits a NH₃ decomposition performance much better than those reported on other Ni-based NH₃ decomposition catalysts, resulting from its favorable textural properties and high Ni loading. In addition, Ni/SBA-15-80 shows excellent catalytic stability, with no activity degradation over an 80-h NH₃ decomposition test. This work reveals the importance of textural properties of support and Ni loading to NH₃ decomposition performance and can provide a new idea for synthesizing high-performance NH₃ decomposition catalysts.     

CO2 reforming of methane over Ni/SBA-15 prepared with β-cyclodextrin – Role of β-cyclodextrin in Ni dispersion and performance

Ni/SBA-15-CD(1/X) catalysts were prepared by the impregnation of a certain amount of Ni(NO₃)₂ and various contents of β-cyclodextrin (CD), in which 1/X indicates the molar ratio of CD to Ni. The physicochemical properties of the catalysts were characterized by BET, XRD, TEM, TPR and TGA, and their catalytic performance in the CO₂ reforming of methane to syngas was evaluated using a fixed-bed quartz reactor. The characterization results revealed that Ni/SBA-15-CD(1/X) prepared with n(CD)/n(Ni) ratios in the range of 1/66–1/33 possessed smaller NiO particles and exhibited stronger interactions between NiO and SBA-15, whereas NiO particles were not well-dispersed on Ni/SBA-15-CD(1/X) catalysts prepared with further CD addition (1/X = 1/8 and 1/1). The reaction results indicated that the better-dispersed Ni/SBA-15-CD(1/X) catalysts, such as Ni/SBA-15-CD(1/66), Ni/SBA-15-CD(1/50) and Ni/SBA-15-CD(1/33), exhibited higher conversions and stronger abilities to resist carbon deposition. Regarding the role of CD in dispersing Ni particles, it could be speculated that complexes were formed between CD and Ni²⁺, as well as NO₃⁻, which would change the state of Ni species during the impregnation and heat treatment processes.     

Biogas reforming over La-promoted Ni/SBA-16 catalyst for syngas production: Catalytic structure and process activity investigation

Biogas, a mixture of CO₂/CH₄, is reasonable for conversion to syngas (H₂/CO) by dry methane reforming (DMR) reaction. The modification of Ni/SBA-16 with a lanthanum promoter using the co-impregnation technique is investigated in this study. The temperature of reaction (600–750 °C), La loading (3.85–11.56 wt%), and Ni loading (10–30 wt%) are the parameters that are varied for maximizing reaction conversions. The synthesized catalysts and SBA-16 supporting material were characterized by several methods before and after reaction. According to the analysis, the existence of La₂O₃ particles on the catalyst's surface has decreased the particle sizes, as well as enhanced their dispersion. Therefore, the maximum CH₄ conversion of 94.21%, CO₂ conversion of 90.12%, H₂ yield of 90.53%, and H₂/CO molar ratio of 2.03 are achieved using 20Ni-5.78La/SBA16 at 700 °C. Besides, this catalyst showed lower deposited coke and higher stability compared with other synthesized catalysts.     

Synthesis,characterization and catalytic performance of MgO-coated Ni/SBA-15 catalysts for methane dry reforming to syngas and hydrogen

A series of MgO-coated SBA-15 mesoporous silica with MgO contents ranging from 2 wt% to 15 wt% have been successfully synthesized by a simple one-pot synthesis method and further impregnated with 10 wt% Ni. Ni/SBA-15 modified with 8 wt% MgO was also prepared by conventional impregnation method. The materials were characterized by means of XRD, N₂ physisorption, TEM by applying high-angle annular dark field (HAADF), XPS, CO₂-TPD, TGA and temperature-programmed hydrogenation (TPH) techniques, and their catalytic performance was tested for methane reforming with CO₂. The results showed that MgO was successfully coated on the walls of mesoporous silica and the mesoporous structure of SBA-15 was well maintained after MgO modification. Compared to MgO-impregnated material, MgO-coated counterpart showed a better order in the mesostructure and more medium basic sites. The addition of MgO enhanced initial catalytic activity of Ni/SBA-15, and the catalyst with 8 wt% MgO coating showed the most excellent catalytic activity. The MgO coating induced an improved dispersion of Ni species and larger medium basic sites than that of MgO impregnation, which led to an enhanced long-term stability and resistance to carbon formation. The deposition of graphitic carbon species during the reaction was the main reason for the deactivation of Ni/SBA-15 catalyst.     

Y2O3-promoted NiO/SBA-15 catalysts highly active for CO2/CH4 reforming

A series of Y₂O₃-promoted NiO/SBA-15 (9 wt% Ni) catalysts (Ni:Y weight ratio = 9:0, 3:1, 3:2, 1:1) were prepared using a sol–gel method. The fresh as well as the catalysts used in CO₂ reforming of methane were characterized using N₂-physisorption, XRD, FT-IR, XPS, UV, HRTEM, H₂-TPR, O₂-TPD and TG techniques. The results indicate that upon Y₂O₃ promotion, the Ni nanoparticles are highly dispersed on the mesoporous walls of SBA-15 via strong interaction between metal ions and the HO–Si-groups of SBA-15. The catalytic performance of the catalysts were evaluated at 700 °C during CH₄/CO₂ reforming at a gas hourly space velocity of 24 L g_cat⁻¹ h⁻¹(at 25 ^°C and 1 atm) and CH₄/CO₂molar ratio of 1. The presence of Y₂O₃ in NiO/SBA-15 results in enhancement of initial catalytic activity. It was observed that the 9 wt% Y–NiO/SBA-15 catalyst performs the best, exhibiting excellent catalytic activity, superior stability and low carbon deposition in a time on stream of 50 h.     

Unveiling the promotion effect of Zr species on SBA-15 supported nickel catalysts for CO2 methanation

Introducing promoters on Ni-based catalysts for CO₂ methanation have been proved to be positive for enhancing their performance. And the correlation of the promotion mechanism and the reaction pathway is significant for designing efficient catalysts. In this contribution, series of Zr species promoted SBA-15 supported Ni catalysts were prepared by citric acid complexation method under a range of Zr/Ni atomic ratios from 0 to 2.5. In situ and ex situ characterizations were carried out. It was found that the addition of citric acid was conductive to improve CH₄ selectivity due to the higher concentrations of Ni⁰ confined in SBA-15, harvesting sufficient H atoms for CH₄ formation following formate pathway via a formyl intermediate. Furthermore, a coverage layer of Zr species was found on the support at Zr/Ni = 1.7, which interacted with the Ni particles, providing higher concentrations of medium basic sites for CO₂ activation. Accordingly, the optimum catalytic performance was obtained on ZrNi-1.7(CI), achieving CO₂ conversion as high as 78.1% and nearly 100% CH₄ selectivity at 400 °C, following the formate hydrogenation pathway. In addition, the ZrNi-1.7(CI) showed good stability owing to the confinement effect of SBA-15 and the Ni–Zr interaction, no carbon deposits were detected after 50 h test.     

Low metal content Co and Ni alumina supported catalysts for the CO2 reforming of methane

Low metal content Co and Ni alumina supported catalysts (4.0, 2.5 and 1.0 wt% nominal metal content) have been prepared, characterized (by ICP-OES, TEM, TPR-H₂ and TPO) and tested for the CO₂ reforming of methane. The objective is to optimize the metal loading in order to have a more efficient system. The selected reaction temperature is 973 K, although some tests at higher reaction temperature have been also performed. The results show that the amount of deposited carbon is noticeably lower than that obtained with the Co and Ni reference catalysts (9 wt%), but the CH₄ and CO₂ conversions are also lower. Among the catalysts tested, the Co(1) catalyst (the value in brackets corresponds to the nominal wt% loading) is deactivated during the first minutes of reaction because CoAl₂O₄ is formed, while Ni(1) and Co(2.5) catalysts show a high specific activity for methane conversion, a high stability and a very low carbon deposition.     

Fabrication and characterization of poly(phenylene oxide)/SBA-15/carbon molecule sieve multilayer mixed matrix membrane for gas separation

A novel multilayer mixed matrix membrane (MMM), consisting of poly(phenylene oxide) (PPO), large-pore mesoporous silica molecular sieve zeolite SBA-15, and a carbon molecular sieve (CMS)/Al₂O₃ substrate, was successfully fabricated using the procedure outlined in this paper. The membranes were cast by spin coating and exposed to different gases for the purpose of determining and comparing the permeability and selectivity of PPO/SBA-15 membranes to H₂, CO₂, N₂, and CH₄. PPO/SBA-15/CMS/Al₂O₃ MMMs with different loading weights of zeolite SBA-15 were also studied. This new class of PPO/SBA-15/CMS/Al₂O₃ multilayer MMMs showed higher levels of gas permeability compared to PPO/SBA-15 membranes. The permselectivity of H₂/N₂ and H₂/CH₄ combinations increased remarkably, with values at 38.9 and 50.9, respectively, at 10 wt% zeolite loading. Field emission scanning electron microscopy results showed that the interface between the polymer and the zeolite in MMMs was better at a 10 wt% loading than other loading levels. The increments of the glass transition temperature of MMMs with zeolite confirm that zeolite causes polymer chains to become rigid.     

Low-temperature catalytic conversion of greenhouse gases (CO2 and CH4) to syngas over ceria-magnesia mixed oxide supported nickel catalysts

Running dry reforming of methane (DRM) reaction at low-temperature is highly regarded to increase thermal efficiency. However, the process requires a robust catalyst that has a strong ability to activate both CH₄ and CO₂ as well as strong resistance against deactivation at the reaction conditions. Thus, this paper examines the prospect of DRM reaction at low temperature (400–600 °C) over CeO₂–MgO supported Nickel (Ni/CeO₂–MgO) catalysts. The catalysts were synthesized and characterized by XRD, N₂ adsorption/desorption, FE-SEM, H₂-TPR, and TPD-CO₂ methods. The results revealed that Ni/CeO₂–MgO catalysts possess suitable BET specific surface, pore volume, reducibility and basic sites, typical of heterogeneous catalysts required for DRM reaction. Remarkably, the activity of the catalysts at lower temperature reaction indicates the workability of the catalysts to activate both CH₄ and CO₂ at 400 °C. Increasing Ni loading and reaction temperature has gradually increased CH₄ conversion. 20 wt% Ni/CeO₂–MgO catalyst, CH₄ conversion reached 17% at 400 °C while at 900 °C it was 97.6% with considerable stability during the time on stream. Whereas, CO₂ conversions were 18.4% and 98.9% at 400 °C and 900 °C, respectively. Additionally, a higher CO₂ conversion was obtained over the catalysts with 15 wt% Ni content when the temperature was higher than 600 °C. This is because of the balance between a high number of Ni active sites and high basicity. The characterization of the used catalyst by TGA, FE-SEM and Raman Spectroscopy confirmed the presence of amorphous carbon at lower temperature reaction and carbon nanotubes at higher temperature.     

Dry reforming of methane over Ni/dendritic fibrous SBA-15 (Ni/DFSBA-15): Optimization,mechanism, and regeneration studies

Dendritic fibrous type SBA-15 (DFSBA-15) was recently discovered with its outstanding catalytic performance and coke resistance as compared to the conventional SBA-15. The operating conditions for dry reforming of methane (DRM) over 10Ni/DFSAB-15 were optimized by using response surface methodology (RSM), followed by stability and regeneration study. Characterization results (TEM and FESEM) confirmed the homogenous distribution of NiO particles with no morphological change in spherical DFSBA-15 upon Ni addition. Process parameters, such as reaction temperature (X₁, 700 °C–900 °C), gas hourly space velocity (X₂, 15,000 mL/g.h ‒ 35,000 mL/g.h), and CH₄/CO₂ ratio (X₃, 1–3) were studied over CO₂ conversion (Y₁), CH₄ conversion (Y₂), and H₂/CO ratio (Y₃). The optimal reaction conditions were found at X₁ = 794.37 °C, X₂ = 23,815.022 mL/g.h, and X₃ = 1.199, with Y₁ = 95.67%, Y₂ = 93.48%, and Y₃ = 0.983. The in-situ FTIR studies of adsorbed CH₄, CO₂, and CH₄ + CO₂ confirmed the formation of unidentate carbonate, bidentate carbonate, and linear carbonyl species as intermediate species. 10Ni/DFSBA-15 presented good reproducibility by using both regeneration medium (air and CO₂/N₂) with two-fold regeneration by air as compared to CO₂/N₂. It was proven that the synthesized 10Ni/DFSBA-15 was appreciably stable and prone to be regenerated by air for DRM under optimal conditions.     

Catalytic performances of Ni-based catalysts on supercritical water gasification of phenol solution and coal-gasification wastewater

Activity and stability of the supported Ni-based catalysts for the gasification performances of phenol solution and coal-gasification wastewater in supercritical water were studied in a continuous reactor at 480 °C, 25 MPa and oxygen ratio of 0.2 for 50 h operation. The influences of the supports (γ-Al₂O₃, active carbon (AC) and carbon nanotube (CNT)) on gas yields, gasification efficiencies for phenol solution were investigated, and the loading amount of Ni were optimized. Results showed that the catalytic activity and the stability of the catalysts followed the order of Ni/CNT > Ni/AC > Ni/γ-Al₂O₃. The activity of Ni/AC and Ni/γ-Al₂O₃ decreased after 30 h continuous operation, and there occurred significant leaching of Ni²⁺. For Ni/CNT catalyst, H₂ yield increased obviously when the loading amount of Ni lower than 15 wt%, while increased little at higher loading amount. Then, 15 wt% Ni/CNT with a thickness of 1.5 mm was coated on 316 L stainless steel (SS316L, an economic material usually used as the reactor material), which can act as a "catalytic tube wall" in reactor. The catalytic activity and corrosion resistance of Ni/CNT/SS316L for the gasification of real coal-gasification wastewater were studied. Results showed that Ni/CNT/SS316L gave a great positive effect on H₂ production. H₂ yield increased from 25.36 mmol/g (total organic carbon) without catalyst to 75.12 mmol/g (total organic carbon) with Ni/CNT/SS316L after operated for 20 h, respectively. However, obvious pealing of the coating was found after 50 h operation. Further study is necessary for the improvement of the coating preparation method.     

The influence of Ni loading on coke formation in steam reforming of acetic acid

Steam reforming of acetic acid on Ni/γ-Al₂O₃ with different nickel loading for hydrogen production was investigated in a tubular reactor at 600 °C, 1 atm, H2O/HAc = 4, and WHSV = 5.01 g-acetic acid/g-cata.h^?1. The catalysts were characterized by temperature programmed oxidation (TPO) and differential thermal analysis (DTA), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results showed that the amount of deposited carbidic-like carbon decreased and graphitic-like carbon increased with Ni loading increasing from 9 to 15 wt%. The Ni/γ-Al₂O₃ catalyst with 12 wt% Ni loading had higher catalytic activity and lower coke deposited rate.     

Carbon dioxide reforming of methane to syngas over ordered mesoporous Ni/KIT-6 catalysts

The ordered mesoporous Ni/KIT-6 (KIT-6, an ordered mesoporous SiO₂) catalysts were prepared by impregnation method for carbon dioxide reforming of methane. The physicochemical properties of the prepared catalysts were characterized by H₂-TPR, XRD, BET, and TEM. The research results show that the specific surface area, pore diameter, crystal size of Ni species, and catalytic performance of the Ni/KIT-6 catalysts are obviously affected by the Ni content. Increasing Ni content results in the increment of the crystal size of Ni species, while the dispersion of Ni species shows the opposite trend. The specific surface area and pore size of the Ni/KIT-6 catalyst with the Ni loading of 3 wt% were 493.3 m² g^?1 and 6.22 nm, respectively. Besides, the Ni species are highly dispersed on the surface of KIT-6 support. Thereby, it exhibits the superior catalytic performance of carbon dioxide reforming of methane to syngas (CO and H₂). At atmospheric pressure, the CO₂ and CH₄ conversions for each catalyst following the order: NK3 ≈ NK4 > NK5 > NK2 > NK1 > bulk Ni. When the reaction temperature is 600 °C, the conversions of CH₄ and CO₂ of the NK3 catalyst are 65.1% and 37.0%, respectively. Meanwhile, it also shows excellent stability.     

Modification of silica supported nickel catalysts with lanthanum for stability improvement in methane reforming with CO2

Dry reforming of methane (DRM) with excessive methane composition at CH₄/CO₂ = 1.2:1 was studied over lanthanum modified silica supported nickel catalysts (Ni-xLa-SiO₂, x: 1, 2, 4, and 6% in the target weight percent of La). The catalysts were prepared by ammonia evaporation method. Nickel phyllosilicate and La₂O₃ were the main phases in calcined catalysts. The modification of La enhanced the formation of 1:1 and Tran-2:1 nickel-phyllosilicate. There existed an optimum content of La loading at 1.50 wt% in Ni–2La–SiO₂ which resulted in its highest reduction degree (95.3%). The catalysts with appropriate amounts of La exhibited higher amount of CO₂ adsorption and created more medium and strong base centers. The sufficient number of exposed metallic nickel sites to catalyze the reforming reaction, as well as enough medium and strong basic sites in Ni–La–SiO₂ interface to accomplish the carbon removal were two important factors to attenuate catalyst deactivation. The catalyst stability evaluated at 750 °C for 10 h followed the order: Ni–2La–SiO₂ > Ni–4La–SiO₂ > Ni–1La–SiO₂ ≈ Ni–6La–SiO₂ > Ni–SiO₂. Ni–2La–SiO₂ catalyst possessed the lowest deactivation behavior, whose CH₄ conversion dropped from 60.2 to 55.9% after 30 h operation at 750 °C, indicating its high resistance against carbon deposition and sintering.     

The reconstruction of Ni particles on SBA-15 by thermal activation for dry reforming of methane with excellent resistant to carbon deposition

The improved Ni/SBA-15 catalysts were prepared by thermal inducing method and applied to dry reforming of methane. The promoting effect exerted by thermal activated reconstruction was studied systematically by means of various characterization techniques. TEM results indicated that the thermal inducing process led to the reconstruction of Ni particles to form ultra-fine Ni nanoparticles (2–3 nm) uniformly distributed on SBA-15. The resulting Ni nanoparticles not only improved catalytic activity but also inhibited the formation of carbon deposition during the DRM reaction. The thermal treatment catalyst with tiny particles presented the superior catalytic performance in the DRM reaction, where H₂/CO ratio was close to 1 and no deactivation was discovered after continuous reaction at 750 °C for 50 h. Additionally, it was found that the metal-support interaction was strengthened observably after the thermal activated reconstruction. The strong interaction anchored Ni particles to prevent their high temperature sintering, thus forming stable catalytic centers. Therefore, the conversions of both CO₂ and CH₄ almost stabilized at 90% and 85%, respectively, for the thermal activated reconstruction samples during the long-term catalytic test.