Pressure-Induced Selectivity Change of Pt/In₂O₃ for CO₂ Hydrogenation: From Methanol Synthesis to CO Formation

In₂O₃ is a unique oxide exhibiting pressure-dependent selectivity in CO₂ hydrogenation, favoring CO formation at atmospheric pressure and methanol at elevated pressures. Metal promoters, particularly platinum, have been used to enhance In₂O₃ activity toward methanol synthesis, but their behavior under atmospheric conditions remains poorly understood. Here, we investigate the pressure-dependent reactivity of platinum-promoted In₂O₃ (Pt/In₂O₃). Pt/In₂O₃ is highly active for the reverse water gas shift (RWGS) reaction at 0.1 MPa, while achieving excellent methanol selectivity at elevated pressures. Catalyst characterization combined with density functional theory (DFT) calculations indicates that CO formation at low pressure proceeds via a redox mechanism, whereas elevated pressure stabilizes CO* intermediates and promotes their hydrogenation to methanol. These results highlight the intrinsic pressure-tunable reactivity of Pt/In₂O₃ and provide mechanistic insight for controlling product selectivity in CO₂ hydrogenation.