Selective hydrogenation of CO2 into dimethyl ether over hydrophobic and gallium-modified copper catalysts

Abstract

Supported Cu catalysts are widely studied for the hydrogenation of CO2 to dimethyl ether (DME). However, they suffer from insufficient durability and DME selectivity. Herein, we overcome these issues by modulating the gallium species and hydrophobic methyl groups to obtain a silica-supported copper catalyst, achieving a Cu/Ga-SiO2-Me catalyst with significantly improved DME selectivity and catalyst durability. Characterizations of the catalysts showed that the gallium species electronically modulated the Cu nanoparticles, resulting in abundant Cuδ+ species in the catalyst, which minimized the reverse water-gas shift reaction and thus reduced CO selectivity. In addition, the methyl groups contributed to the rapid removal of water from the catalyst surface, which hindered Cu sintering and accelerated catalysis. Consequently, the Cu/Ga-SiO2-20Me exhibited a CO2 conversion of 9.7%, selectivities of DME and methanol of 59.3% and 28.4%, and CO selectivity of only 11.3%. The strategy used in this study may provide rational guidance for improving current industrial catalysts.