Photo-thermal catalytic reverse water gas shift reaction over Pd/MaZrOx (M=Sr, SrMn) catalysts driven by "Cycle-double sites"
Wenkang Ni, Min Zeng, Ke Wang, Yunzhi Lin, Zizhong Zhang, Wenxin Dai, Xianzhi Fu
Abstract
Constructing defect sites on the surface of a catalyst is an important strategy used to achieve efficient reverse water gas shift (RWGS) reaction. In this work, the oxygen vacancies (OVs) and Mn2+ site were successfully created on the surface of Pd/SrMnaZrOx catalysts to enhance the adsorption and activation of CO2. Based on the results of in-situ DRIFTS, quasi-situ EPR, and XPS measurements, which revealed that CO2 adsorbed on the OVs and Mn2+ sites and was activated into CO species. Under UV–vis light irradiation, photo-generated electrons from SrMnaZrOx migrated to the surface of Pd nanoparticles, which was favorable for the activation of H2. Meanwhile, visible light causes the conversion of Mn3+ to Mn2+, and promotes the formation of OVs around the converted Mn2+ sites. This formed "cycle-double sites" (both OVs regeneration and Mn2+ reformation) enhances the activity and stability of RWGS reaction on the prepared catalyst with UV–vis light.