Hydrogenation of CO₂ to methanol over In₂O₃ catalyst

The superior catalytic activity of In₂O₃ for CO₂ hydrogenation to methanol is demonstrated here. The experimental results demonstrate that the reaction temperature and pressure have a significant influence on methanol yield. The conversion of CO₂ over In₂O₃ increases with the increase of reaction temperature and pressure. The yield and formation rate of methanol also increase with the increase of reaction pressure. However, they increase firstly with the increase of reaction temperature but start to decrease when the temperature rises above 330 °C. At 330 °C and 4 MPa, the yield of methanol reaches 2.82%, while the methanol production rate reaches 3.69 mol h^-1 kg_cat^-1, higher than many other reported catalysts, which normally show very low selectivity of methanol at such high temperature. This confirms the previous theoretical study that In₂O₃ inhibits the reverse water gas shift, a competitive endothermic reaction for methanol synthesis from CO₂ hydrogenation. The mechanism for CO₂ hydrogenation to methanol over In₂O₃ catalyst has been discussed.