Catalytic hydrotreating by molybdenum carbide and nitride: Unsupported Mo2N and Mo2C/Al2O3

Unsupported molybdenum nitride (Mo2N) and molybdenum carbide supported on alumina (Mo2C/Al2O3) were compared against commercial sulfided MoS2/Al2O3 and Ni-Mo-S/Al2O3 for hydrotreating coal-derived gas oil and residuum at 633 K (360 degrees C) and 13.7 MPa (2000 psig). When the catalytic rates were compared on the basis of active sites measured by chemisorption, the nitrides and carbides were estimated to have activities as much as five times that of Ni-Mo-S/Al2O3 and MoS2/Al2O3. The comparison was based on sites titrated by CO on the carbide and nitride and by O-2 on the sulfided catalysts. The gas oil and resid product quality from the carbide and nitride catalysts was significantly better than the thermal blank, indicating that the materials were active under practical hydrotreating conditions. X-ray photoelectron spectroscopy analysis after reaction of the Mo2N and Mo2C/Al2O3 catalysts indicated that surface sulfiding was not extensive.