CO2 hydrogenation to methanol on Pd–Cu bimetallic catalysts with lower metal loadings

A series of Pd–Cu bimetallic catalysts with a wide range of total loadings (i.e., 2.4–18.7 wt%, Pd/(Pd + Cu) = 0.34 at at⁻¹) were prepared and evaluated for CO₂ hydrogenation to CH₃OH (Methanol). A key observation is the retention of bimetallic promotion of CH₃OH at lower metal loadings. Pd-Cu(2.4)/SiO₂, which contains the lowest metal loading, yields ~1.6× more CH₃OH than the commercial Cu-ZnO-Al₂O₃ catalyst with respect to metal-based space-time yield (STY) at 523 K and 4.1 MPa. However, an enhancement in CO production is realized. Combined with the characterization results, the size effect-surface alloy composition-catalytic performance relationship was discussed. This work provides insights in designing cost-effective Pd–Cu catalysts with lower metal loadings for CH₃OH synthesis via CO₂ hydrogenation.