Redox Behavior of In-O-Ti Interface for Selective Hydrogenation of CO2 to CO in Doped In-TiO2 Catalyst

In the CO2 hydrogenation reaction, selective synthesis of CO at low temperature and high pressure is needed to integrate the reverse water gas shift reaction with Fischer-Tropsch synthesis. Here, we show that a mixed oxide catalyst prepared by doping indium (In) into TiO2 produces CO with the formation rate of 22 mu mol g(-1) s(-1). The CO selectivity was more than 99 % at 350 degrees C and 3 MPa pressure. Moreover, the catalyst was durable for over 100 h on stream. During reaction the interfacial In3+-O-Ti4+ sites were first reduced in presence of H-2 and then oxidized back with CO2 producing CO. Because of the redox mechanism, the formation of methanol and methane was limited. This study shows the development of a promoter-free oxide catalyst for CO2 hydrogenation and the importance of the redox property at the oxide interface for selective hydrogenation of CO2 to CO under unfavorable conditions.

Automated summary

In this study, a mixed oxide catalyst doped with indium (In) was found to selectively synthesize CO at low temperature and high pressure, with a formation rate of 22 μmol g(-1) s(-1). The CO selectivity exceeded 99% at 350℃ and 3 MPa pressure. The catalyst exhibited durability for over 100 hours of continuous operation. The formation of methanol and methane was limited due to the redox mechanism of the catalyst at the oxide interface. This study highlights the development of a promoter-free oxide catalyst for CO2 hydrogenation and emphasizes the importance of the redox property for selective synthesis of CO2 to CO under unfavorable conditions.