Kinetics of toluene disproportionation over unmodified and modified ZSM-5 zeolites

Journal Article · Fri Jan 01 00:00:00 EST 1993 · Industrial and Engineering Chemistry Research; (United States)

DOI:https://doi.org/10.1021/ie00013a008· OSTI ID:6561054

Uguina, M A; Sotelo, J L; Serrano, D P ^[1]

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1. Complutense Univ., Madrid (Spain)

The kinetics of toluene disproportionation has been studied over both unmodified and Si-Mg modified ZSM-5 catalysts using an integral reactor and taking into account the reversibility of the reaction. It has been found that xylene dealkylation is the major secondary reaction, whereas toluene dealkylation can be considered negligible. For the unmodified ZSM-5, heterogeneous models based in the alkyl-transfer mechanism allowed the experimental results to be fit better than first and second pseudohomogeneous models, the best concordance being obtained when toluene adsorption is assumed as the rate-limiting step. The corresponding kinetic equation has been further applied to the modified zeolite (SiMg/ZSM-5), leading to the development of a kinetic model which includes the effect of the toluene and p-xylene intracrystalline diffusion rate and the presence of nonselective acid sites on the external zeolite surface. This model describes adequately the selective formation of p-xylene over modified ZSM-5, reproducing the experimental product distribution with an average relative error of 2.8%.

• OSTI ID: 6561054
• Journal Information: Industrial and Engineering Chemistry Research; (United States), Vol. 32:1; ISSN 0888-5885
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
TOLUENE
DISSOCIATION
XYLENE-PARA
SYNTHESIS
ZEOLITES
CATALYTIC EFFECTS
ADSORPTION
CHEMICAL REACTION KINETICS
DEALKYLATION
KINETIC EQUATIONS
MAGNESIUM
MATHEMATICAL MODELS
PH VALUE
SILICON
SURFACE PROPERTIES
ALKALINE EARTH METALS
ALKYLATED AROMATICS
AROMATICS
CHEMICAL REACTIONS
ELEMENTS
EQUATIONS
HYDROCARBONS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
KINETICS
MATERIALS
METALS
MINERALS
ORGANIC COMPOUNDS
REACTION KINETICS
SEMIMETALS
SILICATE MINERALS
SORPTION
XYLENES
020400* - Petroleum- Processing