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

This work reports the synthesis of InGaO_X 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 InGaO_X(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·g_cat ^-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.