Effect of In2O3 particle size on CO2 hydrogenation to lower olefins over bifunctional catalysts

A reaction-coupling strategy is often employed for CO2 hydrogenation to produce fuels and chemicals using oxide/zeolite bifunctional catalysts. Because the oxide components are responsible for CO2 activation, understanding the structural effects of these oxides is crucial, however, these effects still remain unclear. In this study, we combined In2O3, with varying particle sizes, and SAPO-34 as bifunctional catalysts for CO2 hydrogenation. The CO2 conversion and selectivity of the lower olefins increased as the average In2O3 crystallite size decreased from 29 to 19 nm; this trend mainly due to the increasing number of oxygen vacancies responsible for CO2 and H2 activation. However, In2O3 particles smaller than 19 nm are more prone to sintering than those with other sizes. The results suggest that 19 nm is the optimal size of In2O3 for CO2 hydrogenation to lower olefins and that the oxide particle size is crucial for designing catalysts with high activity, high selectivity, and high stability.