Selective Hydrogenation of Carbon Dioxide to Methanol on Cu–ZnO/SiO2 Catalysts Prepared by Alkoxide Method

Abstract

Abstract Hydrogenation of CO2 to methanol was carried out on Cu–ZnO/SiO2 catalysts at 493 K and 3 MPa with a flow rate of 100 cm3 min−1 (H2/CO2 = 2). Higher selectivity ( > 90%) was observed on the catalysts prepared by the alkoxide method than on a conventional catalyst prepared by the impregnation method. The selectivity was higher on the catalysts pretreated with H2 at a higher temperature, except at 873 K. The activity of the catalyst pretreated at 873 K was extremely low, probably because of alloy formation. The results of XRD, XPS, and EXAFS demonstrate that the active species for methanol formation is a large metallic Cu particle covered with a partially oxidized layer interacting with highly dispersed ZnO.