Synthesis of Highly Active InGaOX Solid Solution Catalysts and Their Superior Performance for CO2 Hydrogenation to Methanol.

This work reports the synthesis of InGaOX solid solution catalysts with varying Ga contents via a one-step hydrothermal method, aiming to enhance the catalytic activity of indium-based catalysts for CO2 hydrogenation to methanol. Comprehensive characterization using XRD, SEM, TEM, H2-TPR, CO2/H2-TPD, and XPS revealed that adjusting the Ga content modulates the crystal structure and surface morphology of the catalysts. An optimal Ga concentration effectively improves the surface redox properties, modifies the distribution of surface oxygen species and the local chemical environment, prevents excessive reduction of the catalyst, promotes the adsorption and activation of CO2, and enhances the hydrogen adsorption/retention and spillover behavior, thereby boosting overall catalytic performance. Among the prepared catalysts, the InGaOX(4/1) sample exhibited the highest activity, achieving a CO2 conversion of 11.7% with a methanol selectivity of 71%, and a space-time yield of 0.46 g·h-1·gcat -1 at 300°C and 3.5 MPa. This performance is outperforms most similar catalysts, offering a promising strategy for the low-cost preparation of highly active indium-based catalysts.