ScholarWorks@숙명여자대학교

초록

The catalytic hydrogenation of CO2 represents a promising strategy for converting renewable resources into value-added fuels and chemicals, driving the development of highly efficient CO2 hydrogenation catalysts. In this study, we elucidate the role of atomically dispersed WOx species in promoting CO2 hydrogenation over heterogeneous catalysts consisting of atomically dispersed Pd and WOx species supported on CeO2. Comprehensive characterization demonstrates that the introduction of atomically dispersed WOx species enhances the reducibility of the Pd species and increase surface oxygen vacancies (approximate to 40% Oads. component), strengthening CO2 adsorption and activation. Under 30 bar, the optimized Pd/0.6WOx-CeO2 achieves a methanol space-time yield of 11.9 gMeOH<middle dot>gPd-1<middle dot>h-1 at 300 degrees C, nearly twofold higher than Pd/CeO2, and maintains performance over 15 h. Kinetic analysis indicates a 29.1 kJ mol-1 decrease in the apparent activation energy for methanol formation (and 22.3 kJ mol-1 for CO at 1 bar), consistent with facilitated H2 activation and vacancy-mediated CO2 adsorption. In situ DRIFTS analysis suggests that WOx modification shifts the dominant surface sequence toward more rapid conversion of carbonate to formate and methoxy species with no detectable bicarbonate intermediate under our DRIFTS conditions, aligning with a vacancy-rich surface. Together, these results support vacancy engineering with atomically dispersed WOx as a design principle for single-atom Pd catalysts, delivering superior CO2-to-methanol performance and robust stability under water-producing conditions.

키워드