A highly efficient Li–Cu/MoOx catalyst constructed by a precursor dispersion and alkali metal-promotion stepwise regulation strategy for the CO2 hydrogenation to methanol reaction

Abstract

The hydrogenation of CO₂ enables the production of high-value fuels and chemicals, contributing to a sustainable and environment-friendly energy transition. Currently, for the CO₂ hydrogenation to methanol reaction, either increasing the CO₂ conversion or improving the methanol selectivity while maintaining high CO₂ conversion is challenging. Herein, a new catalyst loaded with Cu nanoparticles (NPs) dispersed on amorphous MoO_x with Li₂CO₃ as a promoter (denoted as Li–Cu/MoO_x) was constructed via an in situ dispersion and alkali metal-promotion stepwise regulation strategy. At 260 °C and 5 MPa, the as-designed catalyst exhibited a satisfactory catalytic performance with a CO₂ conversion of 13.4% and a methanol selectivity of 88.8%. The methanol selectivity of the Li–Cu/MoO_x catalyst is higher than that of all the Cu-based catalysts reported in the literature to date under the conditions of CO₂ conversion >10% and reaction pressure <8 MPa in a fixed-bed reactor. Furthermore, the Li–Cu/MoO_x catalyst showed an excellent thermal stability. It was found that the in situ dispersion step enabled a high dispersion of Cu NPs and the production of the amorphous MoO_x support, resulting in the formation of more Cu–support interfaces, which increased the number of active sites in the catalyst. The high methanol selectivity was attributed to an alkali metal-promotion step, which increased the Mo⁴⁺ content in MoO_x, leading to a change in the types of active sites. In addition, the strong metal–support interaction (SMSI) in the catalyst was responsible for the high thermal stability. This strategy also has potential for designing other highly efficient catalysts.