CO2 hydrogenation on CeO2@Cu catalyst synthesized via a solution auto-combustion method

Abstract

Cu-based catalysts had been widely used in CO2 hydrogenation process for their excellent performance and high selectivity. Micron-sized Cu powder obtained by ball milling exhibited poor CO2 activity for its large particle size and small specific surface area, limited its catalytic application. In this work, micron Cu powder was modified with CeO2 species synthesized from different cerium precursor salts via a solution auto-combustion method to investigate CO2 hydrogenation activity. This work revealed that CeO2 species formed from cerium acetate precursor salt achieved excellent CO2 performance (1.64 mol/gcat.h at 400 °C), which was 3.8 times and 6000 times higher than that from cerium nitrate salt or cerium chloride salt, respectively. Interestingly, a thick dense CeO2 shell would be formed on micron Cu generated from cerium(III) chloride precursor salt, which inhibited CuOx reduction and had the opposite effect for RWGS reaction. In addition, the CuOx species in CeO2@Cu synthesized from cerium chloride salt resulted in the CH4 selectivity. The enhancement performance of the CeO2@Cu prepared from cerium acetate salt and cerium nitrate salt could be attributed to the oxygen defects formed around the Cu-Ox-Ce interface area and metallic Cu in the RWGS reaction. Cerium precursor salts enhanced the structural integrity of CeO2@Cu and played a vital role in RWGS reaction. These results will support a new direction for exploring micron Cu powder in Cu-based catalysts for CO2 utilization.