Sn doped In2O3 catalyst for selective hydrogenation of CO2 to methanol

Selective hydrogenation of CO2 to methanol is one of the most important ways of resource utilization of CO2, so it is very necessary to develop efficient methanol synthesis catalysts. In this study, the Sn promoter has been incorporated into In2O3 to modify its reducibility and the surface oxygen vacancy, in order to optimize the catalytic performance of In2O3 catalyst for CO2 hydrogenation to methanol. Several characterizations including XRD, TEM, H2-TPR, H2-D2-TPSR, Raman, XPS, and CO2-TPD were conducted to reveal the effect of Sn promoter on the structure and chemistry of the catalysts. The activity tests were performed in a high pressure fixed-bed reactor to study the catalytic performance. The results showed that the Sn atoms were highly dispersed in In2O3 and tended to accumulate on the surface through forming Sn—O—In structure, which promotes the formation of surface oxygen vacancy, and can inhibit the excessive reduction of In2O3. As a result, the Sn promoted In2O3 catalysts exhibited higher methanol selectivity and productivity. The Sn-In2O3 catalyst with a Sn/In molar ratio of 0.5% possessed the optimized catalytic performance, which showed a CO2 conversion of 6.2% and methanol selectivity of 70.4% at the reaction conditions of 300℃ and 3 MPa with GHSV of 15000 ml·g-1·h-1. With further increment of Sn content, the CO2 conversion would slightly decrease, while the methanol selectivity would increase to 80.8%, significantly higher than that of 55.4% on the pure In2O3 catalyst. © 2023 Materials China. All rights reserved.