Ce-modified Ni/SiO2 catalysts via ammonia evaporation method to Regulate nickel phyllosilicate and enhance CO2 methanation performance

CO₂ hydrogenation to methane has been extensively studied due to its high equilibrium conversion rate, mild reaction conditions (low temperature and ambient pressure), and the availability of inexpensive catalysts. The Ni/SiO₂ catalysts are widely utilized for CO₂ methanation, but their catalytic activity at lower temperatures remains inadequate. In this study, the Ni/SiO₂ catalysts modified with different amounts of CeO₂ were prepared by the ammonia evaporation method (AE). The optimal catalyst, 5Ni-Ce/SiO₂, exhibited CO₂ conversion rate exceeding 80 % and CH₄ selectivity ≥ 99 % under 300 °C. A series of characterizations indicate that the nickel phyllosilicate over pure Ni/SiO₂ has been regulated to other more dispersed nickel species like Ni-O-Ce units and thus changes the specific surface area, surface basic sites, and oxygen vacancies, which may be a decisive factor contributing to its optimal catalytic activity. Finally, in-situ DRIFTS was employed to elucidate that 5Ni-CeO₂/SiO₂ follows the *CO and formate reaction pathways for methane production. This study highlights the significance of CeO₂ introduction into Ni/SiO₂ for CO₂ methanation prepared by the ammonia evaporation method.