New Catalysts for Hydroprocessing: Molybdenum and Tungsten Phosphide
Clark, Paul Alexander
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This dissertation describes the preparation and application of a novel class of hydroprocessing catalysts, transition metal phosphides. Concentration was placed on molybdenum and tungsten monophosphides because of the importance of these elements in standard sulfidic hydrotreating catalysts. Transition metal phosphides exist over a wide range of stoichiometry, and their properties have a great deal of variation, ranging from phosphorus poor compounds with metallic electrical properties to phosphorus rich compounds with semiconducting or insulating properties. The x-ray diffraction patterns of the phosphides studied here were unchanged under the conditions of catalytic hydroprocessing, demonstrating their stability toward the hydroprocessing conditions and allowing study of their intrinsic catalytic properties. Materials were prepared in bulk form, supported on alumina, and supported on silica. The mechanism of hydrodenitrogenation on MoP/SiO2 and WP/SiO2 catalysts was investigated by comparison of hydrodenitrogenation reactions of pyridine, piperidine, n-pentylamine, tert-pentylamine, and neo-pentylamine.
- Doctoral Dissertations