Oxidative dehydrogenation of propane over nanodiamond modified by molybdenum oxide

• MoOx-modified nanodiamond catalysts were investigated for ODH of propane.
• Nanodiamond was found a better carrier than carbon nanotubes for MoOx dispersion.
• Low-loading MoOx modified nanodiamond exhibits good catalytic performance.
• sp3–sp2 hybridized structure is formed during the reaction.

MoOx-modified nanodiamond (ND) catalysts were investigated for oxidative dehydrogenation (ODH) of propane. The catalysts were prepared by impregnation method and characterized by TEM, XRD, XPS, Raman and FTIR spectroscopies. ND was found a better carrier than carbon nanotubes (CNTS) for MoOx dispersion. The MoOx species are two-dimensional polymerized MoOx which get covalently bonded onto the ND surface via MoOC bonds. A major portion of Mo6+ species was found, together with a small amount of Mo4+ species. Adding 1 wt% MoOx on ND (1Mo) can increase both propane conversion and propene selectivity, whereas excess MoOx leads to a drastically decrease in propene selectivity due to the aggregation of the MoOx species and the coverage of the active sites of ND. Both ND and 1MoOx/ND catalysts show good stability after a few hours of testing. A sp3–sp2 hybrid structure is formed in situ and the ketonic/diketonic carbonyl groups are generated during the reaction, which are believed to be favourable to the reaction. Our results indicate the modification of ND by low-loading MoOx can improve the selectivity at the same conversion rate, thus enhance the propene yield.

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