Deactivation kinetics of para-selective toluene disproportionation over modified ZSM-5

Journal Article · Sat Jan 01 00:00:00 EST 1994 · Industrial and Engineering Chemistry Research; (United States)

DOI:https://doi.org/10.1021/ie00025a005· OSTI ID:5324455

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

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1. Complutense Univ., Madrid (Spain). Chemical Engineering Dept.

The deactivation kinetics of toluene disproportionation to yield a mixture of benzene and xylenes with a high para-selectivity has been studied using a Si-Mg modified ZSM-5 catalyst. The kinetic model developed includes the deactivation of the main and the secondary reactions and takes into account the influence of the intracrystalline diffusional steps. The best fit of the experimental data was obtained when toluene is assumed to be the coke precursor. The order of deactivation of the main reaction is close to 3, which agrees with the control of the overall reaction rate by the intracrystalline diffusion. The secondary reaction of p-xylene dealkylation is deactivated faster than the main reaction. However, the activity of the secondary reaction of p-xylene isomerization, which takes place only over the external zeolite surface, remains constant and close to unity. These differences among the deactivation rates have been related to the mechanism of deactivation and to the strength of the acid sites involved in each reaction.

• OSTI ID: 5324455
• Journal Information: Industrial and Engineering Chemistry Research; (United States), Vol. 33:1; ISSN 0888-5885
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
BENZENE
SYNTHESIS
CATALYSTS
DEACTIVATION
TOLUENE
CATALYTIC REFORMING
DISSOCIATION
XYLENES
MAGNESIUM
MATHEMATICAL MODELS
SILICON
ALKALINE EARTH METALS
ALKYLATED AROMATICS
AROMATICS
CHEMICAL REACTIONS
ELEMENTS
HYDROCARBONS
METALS
ORGANIC COMPOUNDS
REFORMER PROCESSES
SEMIMETALS
020400* - Petroleum- Processing