Identifying the active site and structure–activity relationship in propane dehydrogenation over Ga2O3/ZrO2 catalysts

ZrO2-based catalysts have attracted extensive attention in propane dehydrogenation (PDH) owing to their environmental compatibility, low costs, and superior catalytic performance. However, the structure–activity relationship and mechanistic analysis of Ga2O3/ZrO2 in PDH are rarely studied where GaOx either acts as an active site or a promoter. Here, Ga2O3/ZrO2 catalysts with different Ga/Zr ratios were synthesized by the impregnation technique, and the structure–activity relationship was revealed by combining complementary in/ex-situ characterization methods with catalytic tests. It is found the rate of propene formation first increases linearly and then reaches a plateau with the increase of Ga2O3 loading, such activity-loading dependence is related to the evolution of Ga2O3 species varying from monodisperse to single-layer and then multilayer states. Activation energy and C3H8-TPSR results suggest the formation of a new active site with high intrinsic activity over Ga2O3/ZrO2. Furthermore, the molecular level reaction mechanism of Ga2O3/ZrO2 in PDH was studied by DFT calculations, which pointed out the active site structure was GaⅡ–O3cⅡ site exhibiting enhanced activation ability toward C–H bond and lower reaction barrier compared with bare ZrO2. This work is expected to offer new insights into understanding the structure–activity relationships over ZrO2-based catalysts for PDH reaction.