NAY-SUPPORTED MOLYBDENUM SULFIDE CATALYSTS .1. CATALYSTS PREPARED VIAIMPREGNATION WITH AMMONIUM HEPTAMOLYBDATE

NaY-supported molybdenum sulfide catalysts with increasing Mo loading have been prepared by impregnation with ammonium heptamolybdate and ch aracterized by means of thiophene hydrodesulfurization (HDS), overall sulfur analysis, temperature programmed sulfidation, N-2 adsorption, X e adsorption, Xe-129-NMR, and high resolution electron microscopy, Aft er impregnation nearly all Mo is located on the exterior of the zeolit e particles, During calcination in air part of the Mo is redistributed , resulting in a higher amount of Mo being located in the zeolite supe rcages. For the sulfided catalysts an amount of Mo comparable to that after calcination is present in the supercages. At the highest Mo load ings the catalysts are incompletely sulfided, due to the presence of l arge ''bulk-like'' molybdenum oxide particles on the outside of the ze olite particles. The amount of Mo present in the supercages, as well a s the thiophene HDS activity of the sulfided catalysts, increases with increasing Mo loading. The small Mo sulfide particles in the supercag es contribute strongly to the thiophene HDS activity. (C) 1996 Academi c Press, Inc.