Highly active and stable mixed-phase In2O3-supported Ni catalyst for CO2 hydrogenation to methanol

Abstract

Ni/In2O3 catalysts perform well for CO2 hydrogenation to methanol. However, there is still room for improvement in terms of methanol selectivity. In this study, Ni/In2O3 catalysts with distinct crystalline phases of indium oxide, namely cubic In2O3 (c-In2O3) and a mixed phase of cubic and hexagonal In2O3 (h + c-In2O3), were synthesized. The results showed that the Ni/h + c-In2O3 catalyst demonstrated the greatest catalytic performance, with a methanol selectivity of 96.7 % and a space time yield of methanol of 15.79 mmol·g−1·h−1 at 2 MPa, 300°C, and 24.0 L·g−1·h−1. Based on the characterization results, we concluded that the improvement of the methanol synthesis performance on the Ni/h + c-In2O3 catalyst was mainly due to improved hydrogen dissociation ability and the increased surface oxygen vacancies. The energy barrier (Ea) of the rate-limiting steps for the CH3OH and CO productions was calculated. The decreased Ea(CH3OH) and increased Ea(CO) indicate the favorable improvement of catalytic activity and selectivity for CH3OH production by Ni/In2O3, especially for Ni/h-In2O3(104).