Ni-exsolved La1-xCaxNiO3 perovskites for improving CO2 methanation

Abstract This work investigates the promoting effect of Ca on CO2 hydrogenation to methane in the highly exsolved Ni particles of La1-xCaxNiO3 perovskite catalysts. TEM images presented that metallic Ni particles are exsolved to the surface under a reducing atmosphere. This exsolution behavior is observed until the Ca ratio (x) becomes 0.4, suggesting that the highly dispersed Ni particles formed by the exsolution can actively adsorb and dissociate H2 molecules. In-situ DRIFT spectroscopy reveals that the surface Ca-sites effectively adsorb CO2 molecules to form reactive carbonates species. XPS analyses and CO methanation tests further show that adding Ca negatively charges the adsorption sites and enhances the reactivity of CO. This surface coordination is optimized by incorporating 0.4 of Ca, presenting facile hydrogenation of CO molecules to CH4. Thus, incorporating 0.4 of Ca into the A-site of LaNiO3 demonstrated the optimized promoting effect on CO2 methanation.