CO2 hydrogenation to methanol over Cu-In intermetallic catalysts: Effect of reduction temperature

Abstract

Abstract Cu-In intermetallic catalysts are prepared by controlled reduction of CuO-In2O3 with hydrogen. The effects of reduction temperature on the catalyst properties and CO2 hydrogenation performance are studied. Three typical reduction steps are shown with increasing the reduction temperature. Especially, after 350\u202f°C reduction, Cu11In9 appears and a Cu11In9-In2O3 intermetallic catalyst (CuIn-350) is obtained. It is shown that the formation of Cu11In9 modulates Cu electronic structure and improves H2 adsorption strength. An interface exists between Cu11In9 and In2O3, illustrating that Cu11In9 interacts closely with In2O3 and thus affects CO2 adsorption strength. It is also found that H2 adsorption capacity is not a principal factor and that CH3OH space-time yield is positively correlated with CO2 adsorption capacity. Furthermore, Cu11In9-In2O3 interface can be seen as the catalytic sites and an interface-catalyzed mechanism is proposed. Due to medium H2 adsorption, excellent CO2 adsorption, numerous Cu11In9-In2O3 interfacial sites and excellent thermal stability, CuIn-350 gives a high CH3OH space-time yield and is recommended for catalyzing CO2 hydrogenation to CH3OH.