To negate the global warming induced by greenhouse gases, carbon capture and utilization technology such as CO2 hydrogenation has been intensively investigated. And this work studies the promoting effect of Ca in the highly exsolved Ni particles of La1-xCaxNiO3 (0 ≤ x ≤ 0.6) perovskite and utilizes as catalyst for CO2 methanation reaction. HAADF-STEM images presented the successful exsolution of metallic Ni particles on the catalytic surface under a reducing atmosphere. However, incorporating Ca over 0.5 directly prevents this exsolution feature, suggesting that excessive Ca incorporation decline the Ni dispersion, leading to the decrease of H2 adsorption and dissociation. In-situ DRIFTS reveal that the surface Ca-sites effectively enhance the adsorption CO2 molecules to form reactive carbonates species. XPS analyses and CO methanation tests further present that adding Ca negatively charges the adsorption sites to facilitate the activation of CO molecules. This characteristic is optimized by varying the amount of Ca insertion, thereby incorporating 0.4 of Ca into the A-site of LaNiO3 demonstrated the optimized promoting effect on CO2 methanation in terms of both CH4 yield and reaction rate.

Promoted CO2 methanation by inserting Ca into the A-site of Ni-exsolved LaNiO3 perovskite catalysts

ACS Spring Meeting 2021

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