Synthesis and Activity of a New Catalyst for Hydroprocessing: Tungsten Phosphide

A tungsten phosphide, WP, hydrotreating catalyst was prepared by temperature-programmed reduction of an X-ray amorphous tungsten phosphate at a heating rate of 0.0167 K s−1 and a 2-h soak at the final temperature of 938 K. Characterization of intermediates quenched at different temperatures revealed a single crystalline reaction product whose specific CO uptake and BET surface areas passed through a maximum of 12 μmol g−1 and 15 m2 g−1, respectively, at 873 K. Heating rate variation measurements gave an apparent first-order activation energy of 148 kJ mol−1 for the reduction. Tungsten phosphide was catalytically active in the hydrodenitrogenation and hydrodesulfurization reactions of a simulated light oil consisting of 20 wt% tetralin, 76 wt% tetradecane, 2000 wppm N as quinoline, 3000 wppm S as dibenzothiophene, and 500 wppm O as benzofuran. Measurements were made in an upflow fixed-bed reactor operated at 3.1 MPa and 643 K and gave conversion levels at steady state for the WP catalyst of 58% HDN and 67% HDS. These conversions were superior to those found for WC, W2N, and WS2 tested under the same conditions.