Toluidine isomerization by HZSM-5
The isomerization of alkylaromatics has been widely studied. Early investigations with homogeneous catalysts, for example, metal halide-hydrogen halide complexes in aromatic solvents, established that the major reaction pathway utilized a series of 1,2-alkyl shifts. Tracer studies with homogeneous catalysts indicated that methyl groups migrated on a ring in an intramolecular mechanism rather than by a series of intermolecular methyl migrations (6,7). On the other hand, alkyl groups more complex than the methyl group - ethyl, n- or isopropyl, t-butyl, etc. - appeared to isomerize by intermolecular shifts. With amorphous silica alumina, the series of 1,2-methyl shifts was the dominant reaction pathway although the apparent selectivity for this mechanism was lower than that obtained with the homogeneous catalyst. With the larger-pore zeolite, LaY, the apparent deviation from the 1,2-methyl shift mechanism was even greater than that for amorphous silica-alumina catalysts. With an intermediate-pore-size zeolite, HZSM-5, xylene isomerization appeared to be nonselective since the primary products consisted of essentially an equilibrium mixture. However, recent tracer studies utilizing (1-/sup 13/C)toluene have shown that the dominant reaction pathway for methyl migration in toluene, a reactant less susceptible to diffusion disguise than the xylene isomers, is by a series of 1,2-methyl shifts.
- Research Organization:
- Kentucky Energy Cabinet Lab., Lexington (USA)
- OSTI ID:
- 7229711
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 111:1; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020400* -- Petroleum-- Processing
ALKYLATED AROMATICS
AMINES
AROMATICS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMICAL REACTORS
CHROMATOGRAPHY
CRYSTAL STRUCTURE
GAS CHROMATOGRAPHY
HYDROCARBONS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
ISOMERIZATION
KINETICS
MASS SPECTROSCOPY
MATERIALS
MICROSTRUCTURE
MINERALS
ORGANIC COMPOUNDS
POROSITY
REACTION KINETICS
REGENERATION
SEPARATION PROCESSES
SPECTROSCOPY
TOLUENE
TOLUIDINES
XYLENES
ZEOLITES