Enhanced low-temperature activity of CO2 methanation: Effect of metal oxide support on the performance of Ni-based catalysts

Abstract

The methanation of carbon dioxide via the Sabatier process is attracting growing attention for power-to-gas (P2G) application. In the current study, a series of 25 wt% Ni-based catalysts were synthesized using solution combustion synthesis (SCS) to investigate the influence of the support on the methanation performance. The results showed that Ni/CeO₂-ZrO₂ catalyst exhibited superior activity, achieving 72.5 % and 95.5 % CO₂ conversion at 250 °C and 300 °C, respectively, while maintaining excellent stability over 100 h of time-on-stream. CO₂-TPD analysis revealed that weak-to-moderate basic sites played a key role in enhancing catalytic activity. This is consistent with XPS results, which indicated a high concentration of surface hydroxyl groups and oxygen vacancies, responsible for the enhanced basicity of the CeO₂-ZrO₂ support. Additionally, the CO-chemisorption measurements confirmed improved Ni dispersion, further contributing to efficient H₂ activation. In situ DRIFT-MS studies identified a reaction pathway involving CO₂ adsorption as carbonate and bicarbonate species, followed by stepwise hydrogenation to methane via formate intermediates. The correlation between turnover frequency (TOF) and the number of weak-to-moderate basic sites supports a dual-site reaction mechanism, where basic sites facilitate CO₂ activation and Ni sites promote H₂ dissociation, both contributing to the remarkable low-temperature carbon dioxide methanation activity.