Mechanism of hydrodenitrogenation (Part 4) infrared spectroscopy of acidic molybdena catalysts
Mo oxide catalysts supported over a complete series of silica-aluminas have been characterized in the oxidic and reduced states, by means of total acidity measurements and by infrared spectroscopy. Ammonia chemisorption was used to titrate the total acidity of the catalysts, and IR absorption of adsorbed pyridine to distinguish Bronsted from Lewis acid sites. The formation of new acidity upon deposition of molybdena on silica-alumina supports was then explained on the basis of a simple surface model. The new acidity is of both Lewis and Bronsted type, the preponderance of one over the other depending on support composition, as well as loading and state of oxidation of Mo. High-alumina supports and low Mo loading favor dispersed Mo species, in particular bidentate and monodentate di-oxo Mo species. The latter is responsible for the new Bronsted acidity. Coordinative unsaturation of polymolybdates is responsible for the new Lewis acidity, which is increased upon reduction of Mo. High-silica supports favor monodentate species (high Bronsted acidity) up to 4 wt % MoO{sub 3}. Beyond that, polymolybdates species and Lewis acidity predominate. 7 refs., 4 figs.
- Research Organization:
- Louisville Univ., KY (USA). Dept. of Chemical Engineering
- Sponsoring Organization:
- DOE/FE
- DOE Contract Number:
- FG22-89PC89771
- OSTI ID:
- 6355791
- Report Number(s):
- DOE/PC/89771-4; ON: DE91002496
- Country of Publication:
- United States
- Language:
- English
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ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AMMONIA
AROMATICS
AZINES
BROENSTED ACIDS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PROPERTIES
CHEMICAL REACTIONS
CHEMISORPTION
DENITRIFICATION
DOCUMENT TYPES
EVALUATION
FUELS
HETEROCYCLIC COMPOUNDS
HYDRIDES
HYDROGEN COMPOUNDS
HYDROGENATION
INFRARED SPECTRA
INORGANIC ACIDS
LEWIS ACIDS
LIQUID FUELS
MINERALS
MOLYBDENUM COMPOUNDS
MOLYBDENUM OXIDES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PROGRESS REPORT
PYRIDINE
PYRIDINES
REFRACTORY METAL COMPOUNDS
SEPARATION PROCESSES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
SPECTRA
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS