Continuous hydrogenation of CO2-derived ethylene carbonate to methanol and ethylene glycol at Cu-MoOx interface with a low H2/ester ratio

The Cu-based catalysts have been widely employed in the hydrogenation of CO2-derived ethylene carbonate (EC) to methanol (MeOH) and ethylene glycol (EG), but still suffered from some problems such as excess hydrogen/ester ratio, unsatisfactory MeOH selectivity and catalyst stability & deactivation. Herein, a MoOx-promoted Cu/SiO2 catalyst, which was prepared via a one-pot modified hydrothermal method and derived from copper phyllosilicate precursors, exhibited superior catalytic performance (89% MeOH yield and 99% EG yield) and good stability (>150 h) at a H2/EC ratio (20). Remarkably, the turnover frequency (TOF) and space time yield of MeOH (STYMeOH) reached up to 17.5 h−1 and 0.207 g⋅gcat−1⋅h−1, respectively, which are among the highest values in the literature data. The characterization results and kinetic studies revealed that modification of Cu species by MoOx obviously changed the electronic properties of Cu species, reduced the activation energy and enhanced the Cu+/(Cu0 + Cu+) ratios. Such modification may lead to possible formation of Cu-O-Mo bond between Cu species and MoOx species located on the periphery of Cu-MoOx interface, which might strengthen the adsorption and activation of EC, stabilize the Cu nanoparticles, and thus improve the selectivity to MeOH and catalyst stability. In addition, MoOx decoration had obvious effect on the strength and quantity of the surface acid sites.