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.