Isomerization of xylene and methylation of toluene on zeolite H-ZSM-5 compound kinetics and selectivity

Journal Article · Tue Jun 01 04:00:00 EDT 1993 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1993.1163· OSTI ID:5990148

Beschmann, K; Riekert, L ^[1]

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1. Institute fuer Chemische Verfahrenstechnik der Universitaet Karlsruhe (Germany)

The alkylation of toluene with methanol and the isomerization of xylene were investigated separately and in detail on zeolite H-ZSM-5 as catalyst. The influence of crystal size alone on rates and product distributions was studied for two Si/Al ratios in the zeolite at 573 and 723 K in a gradientless batch-reactor. The isomer distribution in the xylene resulting from toluene methylation is constant from zero up to at least 50% conversion of the methanol in a stoichiometric mixture, H-ZSM-5 being always para-selective. para-Xylene prevails increasingly in the products when either crystal size, temperature, or Al content in the zeolite increase; essentially pure p-xylene can be obtained in the limit with unmodified H-ZSM-5 as catalyst. The rate of isomerization of xylene alone to an equilibrium mixture of isomers was found to be roughly proportional to the extent of the (external) surface of the zeolite crystals, the ratios of the rates of different reactions in the triangular scheme of isomerization being nearly independent of crystal size. The observations can be understood as resulting from the interaction of reaction an diffusion in the volume of the crystals. 34 refs., 11 figs., 4 tabs.

• OSTI ID: 5990148
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 141:2; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALCOHOLS
ALKYLATED AROMATICS
ALKYLATION
AROMATICS
CATALYSIS
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CRYSTALS
EQUILIBRIUM
HETEROGENEOUS CATALYSIS
HYDROCARBONS
HYDROXY COMPOUNDS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
ISOMERIZATION
KINETICS
MATERIALS
METHANOL
METHYLATION
MINERALS
ORGANIC COMPOUNDS
REACTION KINETICS
SILICATE MINERALS
TOLUENE
ZEOLITES