Regulating the crystal structure of layered double hydroxide-derived Co-In catalysts for highly selective CO2 hydrogenation to methanol

Abstract

Highly selective CO2 hydrogenation faces a significant technological challenge, though many efforts have been made on this subject. Herein, Co-In catalyst with excellent structure was synthesized from layered double hydroxides, and its crystal structures were regulated by H2 reduction for selective CO2 hydrogenation to methanol. As reduction temperature increases, In2O3 crystals are destroyed by degrees, resulting in gradual loss of CO2 adsorption on oxygen vacancies, but more CoIn2 intermetallic compound crystals are generated, which can serve as new active phases to adsorb and activate CO2. Density functional theory calculations show that newly-formed CoIn2 crystals are more inclined to convert massive CO2 to formate intermediate and improve CH3OH selectivity significantly. The CoInLDH catalyst reduced at 350 °C with relatively intact In2O3 crystals and plentiful CoIn2 crystals shows high catalytic performance with CO2 conversion of 13.8% and CH3OH selectivity of 83.7%. This work provides a valuable insight into improving CO2 hydrogenation by catalyst crystal regulation.