Low-temperature CO2 hydrogenation to CO on Ni-incorporated LaCoO3 perovskite catalysts

This work introduces LaCo_1-xNi_xO₃ (x = 0, 0.1, 0.25, and 0.4) perovskite catalysts for enhancing the low temperature performance of reverse water-gas shift (RWGS) reaction. Incorporating Ni lowers the interaction between La-site and B-site, weakening the electron donation from La-site to B-site. The B-site elements with the weak interaction can be easily diffused from the bulk to form exsolved bimetallic Co–Ni alloy on the surface. This different interaction trends further control H₂ dissociation activity and CO desorption that affect CO₂ conversion and CO selectivity, respectively. While the Ni-incorporated catalyst shows a higher metal dispersion to enhance H₂ dissociation activity and increases CO₂ conversion, the La-sites with the weak electron donation further drive the strong adsorption of CO molecules to be additionally hydrogenated, eventually lower CO selectivity. However, incorporating 10 at% Ni into the B site of LaCoO₃ (LaCo_0.9Ni_0.1O₃) achieved a balanced effect between facile H₂ dissociation and CO desorption to maximize RWGS activity. The LaCo_0.9Ni_0.1O₃ catalyst displayed outstanding activity with an average CO₂ conversion of 30.8%, which is close to the equilibrium conversion, and a CO selectivity of 98.8% at 475 °C over 50 h.