Hydrodesulfurization of thiophene, benzothiophene, dibenzothiophene, and related compounds catalyzed by sulfided CoO--MoO/sub 3//. gamma. -Al/sub 2/O/sub 3/: low-pressure reactivity studies
Hydrodesulfurization experiments were carried out with a sulfided CoO--MoO/sub 3//..gamma..-Al/sub 2/O/sub 3/ catalyst in a pulse microreactor operated at atmospheric pressure and temperatures of 350 to 450/sup 0/C. The reactants were hydrogen and pure sulfur-containing compounds (or pairs of compounds), including thiophene, benzothiophene, dibenzothiophene, several of their hydrogenated derivatives, and various methyl-substituted benzothiophenes and dibenzothiophenes. The aromatic compounds appeared to react with hydrogen by simple sulfur extrusion; for example, dibenzothiophene gave H/sub 2/S + biphenyl in the absence of side products. The reactivities of thiophene, benzothiophene, and dibenzothiophene were roughly the same. Each hydrogenated compound (e.g., tetrahydrothiophene was more reactive than the corresponding aromatic compound (e.g., thiophene). Methyl substituents on benzothiophene had almost no effect on reactivity, whereas methyl substituents on dibenzothiophene located at a distance from the S atom slightly increased the reactivity, and those in the 4-position or in the 4- and 6-positions significantly decreased the reactivity. In contrast to the observation of a near lack of dependence of low-pressure reactivity on the number of rings in the reactant, the literature shows that at high pressures the reactivity decreases with an increased number of rings. The pressure dependence of the structure--reactivity pattern is suggested to be an indication of relatively less surfacecoverage by the intrinsically more reactive compounds (e.g., thiophene) at low pressures but not at high pressures. The relative reactivities are also suggested to be influenced by differences in the structures of the catalyst at low and high hydrogen partial pressures, which may be related to the concentrations of surface anion vacancies and the nature of the adsorbed intermediates. 1 figure, 7 tables.
- Research Organization:
- Univ. of Delaware, Newark
- OSTI ID:
- 6374731
- Journal Information:
- J. Catal.; (United States), Vol. 55:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
03 NATURAL GAS
ALUMINIUM OXIDES
CATALYTIC EFFECTS
AROMATICS
CHEMICAL REACTION YIELD
BIPHENYL
COBALT OXIDES
HYDROGEN
CHEMICAL REACTIONS
HYDROGEN SULFIDES
MOLYBDENUM OXIDES
STYRENE
THIONAPHTHENES
THIOPHENE
CATALYSTS
COMPARATIVE EVALUATIONS
HETEROCYCLIC COMPOUNDS
HIGH TEMPERATURE
MEDIUM PRESSURE
MIXTURES
PRESSURE DEPENDENCE
REACTIVITY
TEMPERATURE DEPENDENCE
ALUMINIUM COMPOUNDS
CHALCOGENIDES
COBALT COMPOUNDS
CRYOGENIC FLUIDS
DISPERSIONS
ELEMENTS
FLUIDS
HYDROCARBONS
HYDROGEN COMPOUNDS
MOLYBDENUM COMPOUNDS
NONMETALS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
YIELDS
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)
030500 - Natural Gas- Health & Safety