CO2 hydrogenation to CH3OH promoted by strong CuxO–MgO interactions and non-thermal plasma under mild conditions

Abstract

Herein, we report the strong interaction between Cu_xO and MgO and its crucial role in promoting plasma-catalytic CO₂ hydrogenation to produce CH₃OH. Four MgO supports and corresponding Cu_xO/MgO catalysts were prepared and systematically characterized and tested in plasma-catalytic CO₂ hydrogenation. The results show that MgO supports with lower crystallinity and more defects favor stronger interactions with Cu_xO species, which result in better CO₂ conversion and CH₃OH selectivity in plasma-catalytic CO₂ hydrogenation, achieving 9.1% CO₂ conversion and 46.2% CH₃OH selectivity under ambient reaction conditions (30 °C and 0.1 MPa). In situ FTIR spectra and catalyst characterization results demonstrate that basic sites of MgO and O_ads. species activate CO₂ molecules into CO₃* species, which are further hydrogenated by H species to form the HCOO* and HCO* species on the MgO support. Cu_xO sites further promote the subsequent hydrogenation steps to move the reaction forward more easily to form the CH₃O* intermediate and the CH₃OH product, which could be the main reason why the strong Cu_xO–MgO interactions promote CH₃OH production in plasma-catalytic CO₂ hydrogenation.