Boosting the first CH bond activation of propane on rod-like V/CeO2 catalyst by photo-assisted thermal catalysis

Abstract

Crystalized CeO₂ structures were typically considered potential photocatalysts due to their great capacity to alter the active sites’ size and ability to absorb light. However, the controllable fabrication of well-defined hierarchical structures of CeO₂ with high reactive facets is significant and challenging. Herein, a series of CeO₂ supports including hierarchical flower-like (F-CeO₂), ball-like (B-CeO₂), cube-like (CCeO₂), and rod-like CeO₂(R-CeO₂) supports were prepared by hydrothermal method (B-CeO₂, R-CeO₂ and CCeO₂) or ice-bath method (F-CeO₂) respectively. V atoms were selected as the active atoms and loaded on these supports. Their structure-activity relationship in photo-assisted thermal propane dehydrogenation (PTPDH) was investigated systematically. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N₂ adsorption-desorption isotherms, and Fourier transform infrared spectrum. Results show that R-CeO₂ support exhibits the biggest surface area thus achieving the best dispersion of VO_x species. UV–vis spectrum and photoluminescence spectrum indicate that V/F-CeO₂ has the best light adsorption property and V/R-CeO₂ has the best carrier migration capacity. The activity tests demonstrate that the V/R-CeO₂ has the largest net growth rate and the V/F-CeO₂ has the biggest relative growth ratio. Furthermore, the non-thermal effect was confirmed by the kinetic method, which lowers the propane reaction orders, selectively promoting the first CH bond activation. The light radiation TPSR experiment confirmed this point. DFT calculations show a good linear relationship between the energy barrier and the exchanged electron number. It inspires the design of high-reactive facets for boosting the intrinsic activity of the CH bond in photo-assisted thermal chemical processes.