Mechanism of hydrodenitrogenation (Part 5) x-ray diffraction of molybdenum catalysts
Efficient nitrogen removal from heterocyclic aromatics in liquid fuels calls for the development of catalysts with better HDN activity than is available with the traditional HDS catalysts. In this project it is proposed that the selectivity of the HDN reaction can be affected by an alteration of the catalyst acidity since it is possible that an acidic Hofmann-like deamination pathway is operative in parallel with the hydrogenolysis of saturated C--N--C bonds. To understand better the role of acidic sites in the presence of hydrogenation and hydrogenolysis sites, molybdena was supported on a series of acidic aluminas, and the resulting new acidity and molybdic phases were characterized. X-ray diffraction was utilized to determine the nature of the supported phases of Mo over silica, alumina and silica-aluminas. After impregnation and calcination, the oxidic molybdena formed dispersed species (probably of the dioxo type) over gamma-alumina, and dispersed agglomerates of MoO{sub 3} over silica. However, on silica-alumina, molybdate was found to interact so strongly with the aluminum cations that it formed Al{sub 2}(MoO{sub 4}){sub 3}, possibly by corrosive chemisorption during impregnation, or by Al diffusion into molybdena during calcination. After a treatment of education of reduction with hydrogen at 500{degrees}C, highly dispersed Mo species are formed. These species are x-ray amorphous. Having been derived from different precursors, those species have different reducibility and acidity for different support compositions. 8 refs., 4 figs.
- Research Organization:
- Louisville Univ., KY (USA). Dept. of Chemical Engineering
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- FG22-89PC89771
- OSTI ID:
- 5673083
- Report Number(s):
- DOE/PC/89771-5; ON: DE91013853
- Country of Publication:
- United States
- Language:
- English
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36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure & Phase Studies
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CALCINATION
CATALYST SUPPORTS
CATALYSTS
CHALCOGENIDES
CHEMICAL REACTIONS
COAL LIQUIDS
COHERENT SCATTERING
DECOMPOSITION
DENITRATION
DIFFRACTION
DOCUMENT TYPES
ELEMENTS
FLUIDS
FUELS
HYDROGENATION
LIQUID FUELS
LIQUIDS
METALS
MINERALS
MOLYBDENUM
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PROGRESS REPORT
PYROLYSIS
REDUCTION
SCATTERING
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SURFACES
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS
X-RAY DIFFRACTION