Pressure-Controlled Selectivity in CO2 Hydrogenation over Ag/In2O3 Catalyst

Multiple products are typically formed during CO 2 hydrogenation over oxide-supported metal catalysts, making the regulation of product selectivity both practically and fundamentally important. In this work, a silver-promoted In 2 O 3 catalyst (Ag/In 2 O 3 ) was synthesized using a deposition-precipitation method and employed as a model system to elucidate the pressure-dependent reactivity of the catalyst in CO 2 hydrogenation. A strong electronic metal-support interaction (EMSI) between Ag and defective In 2 O 3 (In 2 O 3-x ) is identified, which promotes the formation of catalytically active Ag-In 2 O 3-x interfacial sites. The Ag/In 2 O 3 catalyst exhibits a 100% CO selectivity at 0.1 MPa, while achieving high methanol selectivity at 5 MPa within the temperature range investigated. Kinetic analysis reveals that CO formation and methanol synthesis share the same active sites. Combined in situ catalyst characterization and theoretical calculations demonstrate that elevated pressure enhances CO adsorption and stabilizes surface CO*, thereby promoting the further hydrogenation of CO* to CH 3 O* and ultimately leading to high methanol selectivity. This work provides mechanistic insights into pressure-controlled selectivity in catalytic CO 2 hydrogenation and offers a promising strategy for tuning product distribution via the change in the pressure.