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Catalytic olefin metathesis represents a vital reaction in the chemical industry, as it provides a feasible route for the interconversion of olefins. However, traditional supported catalysts usually suffer from low activity due to sluggish kinetics for the formation of catalytically active metal‐carbene species. This work tackles this issue by taking phosphoric acid as a promoter and constructing a Brønsted acidic site to cooperate with the MoOx sites, thus facilitating the formation of Mo‐carbene. It turns out that the turnover frequency of propene metathesis over the Mo−P/Al2O3 catalyst is 7.1 times higher than that over the unmodified Mo/Al2O3 catalyst. The combined characterization reveals the promotion of phosphorus results from the alignment of olefin toward adjacent MoOx and thus facilitates formation of active Mo‐carbene species. [ABSTRACT FROM AUTHOR]

A series of the layered double oxides supported molybdenum oxide catalysts were synthesized and evaluated in the oxidative dehydrogenation of ethane with CO2 (CO2-ODHE). The 22.3 wt% Mo/LDO catalyst delivered a 92.3%selectivity to ethylene and a 7.9% ethane conversion at relatively low temperatures. The molybdenum oxide catalysts were fully characterized by XRD, BET, SEM, TEM, UV–vis, Raman TG, and XPS. Isolated [MoO4]2− dominated on the surface of the fresh 12.5 wt% Mo/LDO catalyst. With the increase of the Mo content, the Mo species transformed from [MoO4]2− to [Mo7O24]6− and [Mo8O26]4− on the 22.3 wt% and 30.1 wt% Mo/LDO catalysts, respectively. The redox mechanism was proposed and three Mo species including [MoO4]2−, [Mo7O24]6−, and [Mo8O26]4− showed quite different functions in the CO2-ODHE reaction: [MoO4]2−, with tetrahedral structure, preferred the non-selective pathway; [Mo7O24]6−, with an octahedral construction, promoted the selective pathway; and the existence of [Mo8O26]4− reduced the ability to activate ethane. This work provides detailed insights to further understand the relationship between structure–activity and the role of surface Mo species as well as their aggregation state in CO2-ODHE. [ABSTRACT FROM AUTHOR]