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

Abstract

In the CO 2 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 TiO 2 produces CO with the formation rate of 22 μmol g À 1 s À 1 . The CO selectivity was more than 99 % at 350 °C and 3 MPa pressure. Moreover, the catalyst was durable for over 100 h on stream. During reaction the interfacial In 3 + À OÀ Ti 4 + sites were first reduced in presence of H 2 and then oxidized back with CO 2 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 CO 2 hydrogenation and the importance of the redox property at the oxide interface for selective hydrogenation of CO 2 to CO under unfavorable conditions.