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 GaO_x 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 Ga^Ⅱ–O_3c^Ⅱ 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.