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.