Reaction mechanism of gas-phase ethylbenzene isomerization
The reaction mechanism of gas-phase ethylbenzene isomerization over bifunctional alumina- or zeolite-supported 0.5% by wt platinum catalysts was studied in a fixed-bed pulse microreactor by determining the product distributions in the conversion of ethylbenzene and of eight probable C/sub 8/ intermediates at 300/sup 0/-400/sup 0/C and 1.8 atm. Over the Pt/Al/sub 2/O/sub 3/ catalyst, xylenes are formed from ethylbenzene mainly via ethylcyclohexene to 1,2-methylethylcyclopentene to 1,2-dimethylcyclohexene to o-xylene, which corresponds to predictions from a bifunctional mechanism, in which only skeletal rearrangements of tertiary carbocations are considered to be rate-determining. Over Pt/zeolite catalysts with higher support acidity, skeletal isomerizations via both tertiary and secondary carbocations contribute to the measured product distributions. In ethylbenzene isomerization, the yield of C/sub 8/ naphthenes decreased from 60 mole % at 300/sup 0/C to zero at 400/sup 0/C and those of C/sub 8/ aromatics and xylenes passed through maxima of approx. 90% at 380/sup 0/C and 20% at 340/sup 0/C, respectively.
- Research Organization:
- Ruhr Univ., Bochum
- OSTI ID:
- 6337042
- Journal Information:
- Ind. Eng. Chem., Prod. Res. Dev.; (United States), Journal Name: Ind. Eng. Chem., Prod. Res. Dev.; (United States) Vol. 18:4; ISSN IEPRA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201 -- Chemical & Physicochemical Properties
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ALKANES
ALKENES
ALKYLATED AROMATICS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AROMATICS
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMICAL REACTORS
CYCLOALKANES
CYCLOALKENES
ELEMENTS
HIGH TEMPERATURE
HYDROCARBONS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
ISOMERIZATION
KINETICS
MATERIALS
MEDIUM PRESSURE
METALS
MINERALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PACKED BED
PLATINUM
PLATINUM METALS
REACTION INTERMEDIATES
REACTION KINETICS
TRANSITION ELEMENTS
XYLENES
YIELDS
ZEOLITES