Ammonization-treated CuMo catalyst for efficient and selective CO2 hydrogenation to methanol

A highly effective catalyst is desired for CO₂ selective hydrogenation to methanol due to the kinetic limitation of this process, considering the heavy impact of CO₂ emission on global environment. Herein, a type of ammonization-treated CuMo catalyst was developed for CO₂-to-methanol hydrogenation, which contains MoN and Mo₂N species. The effect of catalyst preparation conditions on the physicochemical properties of the resulting sample was systematically investigated using multiple characterization techniques, including physical N₂ adsorption and desorption isotherms, XRD, HRTEM, XPS, Cu Auger spectra, H₂-TPR and CO₂-TPD. Structure-activity relationships analysis revealed that the proportion of Cu⁰ and Mo^δ+ (1 < δ < 4) in the catalyst is linearly correlated to the CO₂ transformative rate and methanol selectivity, respectively, which is considered to show synergistic effect on methanol production. Consequentially, the methanol production could reach up to 177.2 mg/g_cat/h with a selectivity of 95.7 % at 230 °C and 4 MPa. In addition, the catalytic mechanism exploration employing in situ IR indicated the CO₂ hydrogenation towards methanol follows the formate route, and the Mo^δ+ species facilitated the stabilization of CO₂-derived reactive intermediates on the catalyst surface. Additionally, kinetic studies reveal methanol formation is primarily limited by CO₂ adsorption/activation rather than H₂ dissociation.