Hydrogenation of alkenes over cobalt/molybdenum/alumina catalyst
The hydrogenation of nine C/sub 2/-C/sub 10/ 1-alkenes, cis- and trans-2-butene, and 2,3-dimethyl-2-butene was studied at 300/sup 0/C and various hydrogen-alkene ratios on a commercial 12% MoO/sub 3//43% CoO/alumina hydrotreating catalyst. All alkenes had a maximum raction rate at approx. 0.15 mole fraction alkene in hydrogen, and the magnitude of the maximum rate varied from 0.62 mole/hr kg catalyst for 2,3-dimethyl-2-butene to 46 mole/hr kg catalyst for ethylene. The rates did not depend on the size and number of substituents on the double-bonded carbons, as they do in metal-catalyzed hydrogenation. Cis- and trans-2-butene, 2,3-dimethyl-2-butene, and 2,3-dimethyl-1-butene had comparable reactivities which suggested that in the slow step, they had already changed into an identical intermediate species. The maximum rates were correlated to the Taft (SIGMA)E/sup 0/(s) constants of substituents in the half-hydrogenated state; 3,3-dimethyl-1-butene deviated from the correlation towards higher reactivity, probably caused by steric acceleration. The kinetics could be described with a four-step reaction scheme within the Langmuir-Hinshelwood framework. Of the four steps, i.e., dissociative hydrogen adsorption, alkene adsorption, surface reaction with one hydrogen, and surface reaction of the half-hydrogenated species with a second hydrogen, the last step was rate-determining.
- Research Organization:
- Inst. Chem. Process Fundam., Czech. Acad. Sci.
- OSTI ID:
- 6318569
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 64:1; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
10 SYNTHETIC FUELS
ALKENES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COBALT
CONCENTRATION RATIO
ELEMENTS
HYDROCARBONS
HYDROGENATION
KINETICS
METALS
MOLYBDENUM
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
QUALITATIVE CHEMICAL ANALYSIS
REACTION INTERMEDIATES
REACTION KINETICS
STEREOCHEMISTRY
TRANSITION ELEMENTS