Promoted Cadmium Catalysts Supported on TiO2 for Efficient CO2 Hydrogenation to Methanol.

Among various CO2 utilization strategies, methanol synthesis via hydrogenation has been extensively studied due to its technological maturity and broad downstream applications. However, the development of catalysts that simultaneously provide high activity, selectivity, and cost-effectiveness remains challenging. This work investigates cadmium-based catalysts for CO2 hydrogenation to methanol, examining the influence of support composition, crystal phase, and metal promotion on catalytic performance. It was found that Cu-promoted cadmium sites supported on TiO2 with a mixed-phase of anatase and rutile markedly enhanced catalytic performance. Under optimized conditions (5 MPa and 290°C), the CdCu/TiO2 catalyst achieved a methanol selectivity of 82% at a CO2 conversion of 15% or a methanol selectivity of 78% at a CO2 conversion of 18% at different space velocities. Our characterization demonstrates that the loading of cadmium onto mixed-phase TiO2 provides weak basic sites that favor CO2 adsorption and activation. The combination with a trace of Cu facilitates the reduction of cadmium, thus promoting the hydrogenation reactivity. The synergistic interaction among Cd, Cu, and the mixed-phase TiO2 collectively promotes methanol formation. This study demonstrates a cost-effective and alternative catalyst for CO2 hydrogenation and offers insights into structure-activity relationships for catalyst design.