Ternary copper-cerium-zirconium mixed metal oxide catalyst for direct CO2 hydrogenation to methanol

Abstract

CuCe, CuZr and CuCeZr mixed metal oxide catalysts were prepared by one step co-precipitation method and used for direct CO2 hydrogenation to methanol. It is found that the maximum CO2 conversion of 14.3% and the highest CH3OH space time yield of 5.15 mmolCH3OH·h−1·gcat−1 can be obtained over the ternary catalyst synthesized at the ratio of CeO2/ZrO2 = 1 with the CuO content kept at 30 wt%. The combination of Cu, Ce and Zr oxides increases the amounts of easily reducible CuO species and oxygen vacancies, thereby resulting in high activity for CO2 conversion. Furthermore, the ternary catalyst has a higher CO2 adsorption capability at both weak and moderate basic sites, which can further enhance CO2 reduction. The physiochemical properties-activity correlation study suggests that the ternary catalyst exhibits excellent structural properties, reducibility and surface chemical characteristics, which determines catalytic performance of CO2 hydrogenation. Moreover, the proposed reaction mechanism shows that formaldehyde is a common intermediate for the formation of CH3OH and CO.