NiCo composite catalysts for CO2 methanation: the effect of preparation methods on catalyst structure and activity

Abstract

The tuning of catalyst structures is a significant strategy to produce highly active catalysts. Five primary methods were used herein to prepare NiCo composite catalysts, which were named NiCo-SG (sol–gel method), NiCo-PC (precipitation method), NiCo-WT (hydrothermal method), NiCo-ST (soft template method), and NiCo-HT (hard template method). Characterization indicated that there were different surface and bulk properties for these catalysts. Activity evaluation was subsequently conducted using CO₂ methanation as a probe reaction. The results showed that the activity of CO₂ methanation on the catalyst was positively correlated with the absorption of CO₂, and with high CO₂ methanation for NiCo-ST and NiCo-HT: the highest CH₄ formation rates were 4.55 and 4.56 × 10⁻⁵ mol g_cat⁻¹ s⁻¹, respectively. This was attributed to the Ni–Co alloy and spherical clusters of the former and the large specific surface area and developed bimodal mesoporous structure of the latter.