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), Vol. 18:4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALUMINIUM OXIDES
CATALYTIC EFFECTS
AROMATICS
ISOMERIZATION
CYCLOALKANES
YIELDS
PLATINUM
ZEOLITES
CATALYST SUPPORTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTORS
CYCLOALKENES
HIGH TEMPERATURE
MEDIUM PRESSURE
PACKED BED
REACTION INTERMEDIATES
XYLENES
ALKANES
ALKENES
ALKYLATED AROMATICS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
HYDROCARBONS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
KINETICS
MATERIALS
METALS
MINERALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REACTION KINETICS
TRANSITION ELEMENTS
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)
400201 - Chemical & Physicochemical Properties