Unraveling the real active site of reaction-induced trivalent vanadium ion in VOx/Al2O3 catalysts for boosting photothermal catalytic propane non-oxidative dehydrogenation

Herein, nano-catalysts of vanadium oxides (VOx) deposited on Al2O3 support were synthesized by the impregnation method. The VOx/Al2O3 catalysts show super-catalytic performances during photothermal propane non-oxidative dehydrogenation (PDH) reaction, and their catalytic performances are strongly dependent on the surface states of supported VOx. The propane conversion of VOx/Al2O3-25 catalyst is 20.7 % at 480 °C under irradiation, and its relative deactivated rate is 0.018 in 12 h. Based on in-situ structure characterizations, the V2O5 on the surface of the support is transformed into the mono-layer dispersed VOx during the photothermal PDH, which can further be reconstructed into highly dispersed V2O3 nanocrystals induced by the reaction conditions. Combined with the results of experiments and theoretical calculations, the role of in-situ formed V2O3 is revealed: the unique 3D structure of V3+ ions can induce the localized surface plasmon resonance effect and strengthen visible light adsorption, which promotes C-H breaking in C3H8 molecules. [Display omitted] •Surface state of VOx is carefully controlled by the loading amount of metal.•VOx shows strong structure-dependent photothermal catalytic performance.•V2O5 can be reconstructed into polymeric VOx and even V2O3 induced by propane.•3D structure of V3+ ion induce the LSPR effect and strong visible light adsorption.•The enhanced catalytic performance is attributed to the photothermal effect of VOx.