CVD preparation of alumina-supported niobium nitride and its activity for thiophene hydrodesulfurization

Niobium nitride was synthesized on a Si(400) substrate and a gamma-alumina pellet using a CVD method with a stream of NbCl5/Ar, NH3, and H-2 gases at 723-973 K under reduced pressure. The composition and surface properties of the deposited niobium nitride were analyzed using XRD and XPS measurements . The activity of alumina-supported niobium nitrides for the hydrodesulfuri zation (HDS) of thiophene at 673 K and atmospheric pressure was determined. The alumina had a surface area of 177 m(2) g(-1) and the alumina-supported niobium nitride catalyst had surface areas of 179-190 m(2) g(-1). Although the catalysts had low activity in the initial stages, the activity increas ed after 200-300 min started to about three times the initial activities. X PS analysis indicated that the activity of the niobium nitride catalysts wa s decreased by sulfur accumulation on the surface and nitrogen released fro m niobium nitride. The relationship between the surface properties of the n iobium nitride catalysts and the activities for thiophene HDS is discussed. (C)2000 Elsevier Science B.V. All rights reserved.