Selective and Stable Pt Catalysts for the Catalytic Conversion of Captured CO 2 to Methanol in an Advanced Water-Lean Postcombustion Solvent

We have successfully combined CO 2 capture and conversion, which eliminates the need for the energy-intensive steps of sorbent regeneration, CO 2 compression, and transportation. The exothermic conversion process regenerates the sorbent for further capture and conversion cycles. In this study, we evaluated supported Pt catalysts (over TiO 2, ZrO 2, or MoO 3 ) for converting CO 2 captured in a single-component, water-lean postcombustion solvent (EEMPA) into methanol. Pt supported on MoO 3 and ZrO 2 showed the highest methanol productivity and selectivity, respectively, among the catalysts evaluated. This study introduces a catalyst system that substantially reduces degradation in amine carbon capture solvents and demonstrates stable catalytic performance, marking a significant advancement over previous findings. Solvent durability was best with Pt/MoO 3, attributed to the lack of detectable acidic or basic sites on its surface. Both Pt/MoO 3 and Pt/ZrO 2 catalysts maintained stable performance over 100 h of continuous operation. The higher methanol productivity with Pt/MoO 3 is likely due to the significantly high H 2 spillover under reaction conditions, which promotes the formation of oxygen vacancies. However, further mechanistic investigation is necessary to conclusively establish this relationship. The higher methanol selectivity (>99%) of Pt/ZrO 2 is believed to be due to its strong basic sites, which reduce methanol adsorption and suppress methane formation. Our findings emphasize the importance of modulating acidic and basic sites on the catalyst surface to enhance methanol selectivity while preserving the integrity of the capture solvent.