New catalysts for hydroprocessing: Bimetallic oxynitrides II. Reactivity studies

Bimetallic oxynitrides of the type M1MIIOxNy were used as catalysts in hydrotreating reactions at 3.1 MPa and 643 EC. The catalysts were prepared by nitriding bimetallic oxide precursors, where MoO3 or WO3 was one of the components, as described in the companion paper. The reactions were studied in a three-pl-rase trickle-bed reactor operated at 3.1 MPa and 643 It. The feed was a model liquid mixture containing 3000 ppm sulfur (dibenzothiophene), 2000 ppm nitrogen (quinoline), 500 ppm oxygen (benzofuran), 20 wt% aromatics (tetralin), and balance aliphatics (tetradecane). The activities of the bimetallic nitrides rt ere compared to a commercial sulfided Ni-Mo/Al2O3 catalyst tested at the same conditions. The bimetallic oxynitrides were active for HDN of quinoline with V-Mo-O-N showing higher HDN activity than the commercial sulfided Ni-Mo-S/Al2O3 catalyst. The HDS activity of the bimetallic oxynitrides ranged from 9 lo 37% with Co-Mo-O-N showing the highest HDS activity among the oxynitrides tested. X-ray diffraction analysis of the spent catalysts indicated that the oxynitrides consisting of early transition metals (Group 4-Group 6) were tolerant of sulfur, while catalysts involving metals of Group 7 and Group 8 showed bulk sulfide phases. X-raf photoelectron spectroscopic analysis of the catalysts before and after the reaction indicated the incorporation of sulfur on the surface of the catalysts after prolonged exposure to the reactants. (C) 1998 Academic Press.