In view of the research significance and the huge market potential, the development of non-precious metal catalyst materials to replace precious Pt-based and environment-unfriendly Cr-based catalysts to achieve a lower cost and more efficient direct dehydrogenation of propane to propylene (PDH) reaction process. By controlling the synthesis of Co2+ active sites highly dispersed on γ-Al2O3 nanosheet supports, the stable and efficient propane C-H bond activation and catalytic performance of PDH were obtained. The Co/Al2O3 catalysts prepared by different synthesis methods were compared to obtained the accurate structure-activity relationship of Co2+-catalyzed PHD reaction. The several characterization demonstrated that the impregnation (IMP) catalyst is mainly composed of Co3O4 in the aggregate state, while in the hydrothermal (HT) catalyst, the isolated Co2+ ions occupy the tetracoordinate position and are highly dispersed on the γ-Al2O3 nanosheet carrier. The structure of HT catalyst before and after the reaction did not change significantly , and the Co element always maintained the +2 valence state and the highly dispersed Co2+ ion distribution state . The structure of IMP catalyst Co3O4 was unstable during the reaction, and the XRD peak of carbon deposition was observed. TGA showed that the carbon content of the IMP sample after the reaction was 28.3%, while the HT sample was only 3.6%. Propylene is more easily desorbed from the surface of HT catalyst, avoiding the production of by-products and carbon deposits, explaining the higher activity of the Co2+ active site, selectivity and stability against carbon deposition (C3H6-TPD). Based on the understanding of the structure-activity relationship, the hydrogenation activity and stability of the highly dispersed CoII catalyst can be further improved by optimizing the Co content and inhibiting the acid sites by the Si promoter.

Stable Co2+ sites incorporated in γ-Al2O3 sheet for catalytic propane dehydrogenation

2019 Spring National Meeting

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