Abstract
Ni nanoparticles encapsulated within La2O3 porous system (Ni@La2O3), the latter supported on SiO2 (Ni@La2O3)/SiO2), effectively inhibit carbon deposition for the dry reforming of methane. In this study, Ni@La2O3/SiO2 catalyst was prepared using a one-pot colloidal solution combustion method. Catalyst characterization demonstrates that the amorphous La2O3 layer was coated on SiO2, and small Ni nanoparticles were encapsulated within the layer of amorphous La2O3. During 50 h of dry reforming of methane at 700 °C and using a weight hourly space velocity (WHSV) of 120,000 mL gcat−1 h−1, the CH4 conversion obtained was maintained at 80%, which is near the equilibrium value, while that of impregnated Ni–La2O3/SiO2 catalyst decreased from 63% to 49%. The Ni@La2O3/SiO2 catalyst exhibited very good resistance to carbon deposition, and only 1.6 wt% carbon was formed on the Ni@La2O3/SiO2 catalyst after 50 h of reaction, far lower than that of 11.5 wt% deposited on the Ni–La2O3/SiO2 catalyst. This was mainly attributed to the encapsulated Ni nanoparticles in the amorphous La2O3 layer. In addition, after reaction at 700 °C for 80 h with a high WHSV of 600,000 mL gcat−1 h−1, the Ni@La2O3/SiO2 catalyst exhibited high CH4 conversion rate, ca. 10.10 mmol gNi−1 s−1. These findings outline a simple synthesis method to prepare supported encapsulated Ni within a metal oxide porous structure catalyst for the dry reforming of methane reaction.
Highlights
Dry reforming of methane (DRM) is a promising process, as it can simultaneously convert CO2 and CH4 present in CO2 -rich natural gas reservoirs to produce syngas
For the Ni@La2 O3 /SiO2 catalyst, small Ni particles were encapsulated within an amorphous La2 O3 layer and supported on SiO2
It is noted that the Ni@La2 O3 /SiO2 catalyst has a significantly lower specific surface area compared with the recently reported mesoporous Ni–La2 O3 (172 m2 .g−1 ) [42] and Ni–La2 O3 /SiO2 (190 m2 g−1 ) [38] catalysts for DRM
Summary
Dry reforming of methane (DRM) is a promising process, as it can simultaneously convert CO2 and CH4 present in CO2 -rich natural gas reservoirs to produce syngas. The latter serves as the raw material to produce liquid fuels through gas-to-liquid technology (via Fischer–Tropsch synthesis) [1]. Ni-based catalysts, due to good catalytic activity and low cost, have been widely investigated for the DRM reaction [8,9,10]. Ni-based catalysts are prone to carbon deposition and metal sintering during DRM [11,12]. Designing a DRM catalyst that resists against carbon deposition and metal sintering could be accomplished by making appropriate choice of support, promoter, structure, and methods of preparation [2,3,4]
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