Molybdenum Carbide Modified Nanocarbon Catalysts for Alkane Dehydrogenation Reactions

Nucleophilic sites on nanocarbon catalysts act as promoters for homolytic cleavage of aliphatic C–H bond. In this study, we report a hybrid catalyst composed of Mo2C and nitrogen-doped onion-like carbon (NOLC) with enhanced capability for C–H bond activation in direct dehydrogenation (DH) reaction of ethylbenzene (EB). The enhanced activity of the Mo2C/NOLC catalyst over unmodified NOLC in EB DH is attributable to the promoted C–H bond activation by Mo2C, as characterized by the lower activation energy and the kinetic isotope effect using deuterated EB. Our XPS, XRD, and Raman spectroscopy results show that the hybrid catalyst is structurally robust under the reaction condition. The increase in nucleophilicity of the oxygen active sites in NOLC is evidenced by an overall shift of the O 1s peaks to lower binding energies after Mo2C modification. The DFT calculation further provides mechanistic insights into the electron-transfer process from Mo2C to the ketonic carbonyl groups.