Abstract
A Pd-2.0/CZZ catalyst (CeZrZnOx supported Pd catalyst with 2.0 wt% Pd) with dendritic morphology and highly dispersed Pd was prepared for methanol (MeOH) synthesis from CO2 hydrogenation. The deposition-precipitation method, higher specific surface area, and pore volume of CZZ support improve the dispersion degree of Pd on the CZZ support. The ultra-dispersed and optimized amount of Pd plays a crucial role in H-2 dissociation, generating more spillover hydrogen on the Pd active sites, thus improving the CO2 hydrogenation performance. Moreover, introducing the optimized Pd of the Pd-2.0/CZZ catalyst increases Ce3+/Ce4+ ratios, which are critical in generating more oxygen vacancies of the CZZ support, thus promoting the adsorption and activation of CO2 molecules. Pd-2.0/CZZ catalyst presents the highest CO2 conversions (29.1 %), superior MeOH selectivity (43.8 %), highest MeOH yield (12.7 %), highest turnover frequency (TOF) (87.3 h(-1)), highest STY (5.11 mol(MeOH) kg(-1)h(-1)) and excellent 100 h long-term stability among a series of Pd-x/CZZ catalysts and the reference PdZn/CZ-Co catalyst. The in situ DRIFTS and density functional theory (DFT) simulation suggests that Pd-2.0/CZZ catalyst with adequate Pd particle size and relatively high Pd metal dispersion promotes the pathway to *HCOO and *CH3O as primary intermediates of CO2 hydrogenation to MeOH. (C) 2022 Elsevier Inc. All rights reserved.