The growing need for alternative sources of transportation fuels encourages the development of new hydrotreatment catalysts. These catalysts must be active and more hydrogen efficient than the current commercial hydrotreatment catalysts. Molybdenum nitrides and carbides are attractive candidate materials possessing properties that are comparable or superior to those of commercial sulfide catalysts. This research investigated the catalytic properties of γ-Al 2 O 3supported molybdenum nitrides and carbides. These catalysts were synthesized via temperatureprogrammed reaction of supported molybdenum oxides with ammonia or methane/hydrogen mixtures. Phase constituents and compositions were determined by X-ray diffraction, elemental analysis, and neutron activation analysis. Oxygen chemisorption was used to probe the surface properties of the catalysts. Specific activities of the molybdenum nitrides and carbides were competitive with those of a commercial sulfide catalyst for hydrodenitrogenation (HDN), hydrodesulfurization (HDS), and hydrodeoxygenation (HDO). For HDN and HDS, the catalytic activity on a molybdenum basis was a strong inverse function of the molybdenum loading. Product distributions for the HDN, HDO, and HDS of a variety of heteroatom compounds indicated that several of the nitrides and carbides were more hydrogen efficient than the sulfide catalyst.

Molybdenum nitrides have been shown to be active hydrotreating catalysts. We explored the hydrotreating activities of supported Mo nitrides. It was observed that the hydrodenitrogenation and hydrodesulfurization activities were inverse functions of the molybdenum loading. By using oxygen chemisorption and carbon monoxide temperature programmed desorption, we were able to characterize the particle morphology of the nitrides.

Early transition metal carbides and nitrides have been shown to be active for the hydrotreatment of model compounds and petroleum crudes. In this paper we describe our investigations of the structural and compositional properties of γ-Al2O3-supported molybdenum carbides and efforts to correlate these properties with their pyridine and quinoline hydrodenitrogenation (HDN) activities. The HDN activities of the materials scaled linearly with the loading and oxygen chemisorptive uptake. Oxygen chemisorption results also suggested that the molybdenum carbide particles were highly dispersed and perhaps raft-like. Using temperature programmed desorption and infrared spectroscopy of carbon monoxide, we were able to identify two types of sites on the carbides; sites “on top” of the particle and sites at the perimeter. We have tentatively concluded that the most active sites for HDN were “on top” of the supported carbide particles.