CO₂ hydrogenation to methanol over PdZn catalysts on bimetallic modified dendritic mesoporous silica nanospheres

Catalysts with the CeTi bimetallic modified dendritic mesoporous silica nanospheres (CTD) as supports, and the PdZn as active metal phase, PdZn/CTD catalysts with higher Pd metal dispersion and more oxygen vacancies were synthesized for efficient CO₂ hydrogenation to methanol (MeOH). The modification of PdZn/CTD using CeTi metals can increase the dispersion of PdZn and improve the Ce³⁺/Ce⁴⁺ ratios. Higher active metal dispersion of PdZn/CTD catalyst is conducive to more H₂ adsorption and to the expose of activation sites. Higher Ce³⁺/Ce⁴⁺ ratio of PdZn/CTD is beneficial to generate more oxygen vacancies, which can adsorb and activate CO₂ molecules efficiently. The optimized PdZn/CTD catalysts exhibit superior CO₂ conversion (33.6 %), MeOH selectivity (32.9 %), MeOH yield (11.1 %), TOF value (22.5 h⁻¹), space–time yield (STY) (4.44 mol_MeOH kg^-1 h⁻¹) and 100 h long-term stability. Besides, through in-situ DRIFTS, HCOO* and CH₃O* species are found to be the primary intermediates of the CO₂ hydrogenation to MeOH reaction over the PdZn/CTD catalysts.