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

Abstract

This work introduces LaCo1-xNixO3 (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 (LaCo0.9Ni0.1O3) achieved a balanced effect between facile H2 dissociation and CO desorption to maximize RWGS activity. The LaCo0.9Ni0.1O3 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.