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

Abstract

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.

Authors:
; ; ;  [1]
  1. Complutense Univ., Madrid (Spain). Chemical Engineering Dept.
Publication Date:
OSTI Identifier:
5324455
Resource Type:
Journal Article
Journal Name:
Industrial and Engineering Chemistry Research; (United States)
Additional Journal Information:
Journal Volume: 33:1; Journal ID: ISSN 0888-5885
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Uguina, M A, Sotelo, J L, Serrano, D P, and Valverde, J L. Deactivation kinetics of para-selective toluene disproportionation over modified ZSM-5. United States: N. p., 1994. Web. doi:10.1021/ie00025a005.
Uguina, M A, Sotelo, J L, Serrano, D P, & Valverde, J L. Deactivation kinetics of para-selective toluene disproportionation over modified ZSM-5. United States. https://doi.org/10.1021/ie00025a005
Uguina, M A, Sotelo, J L, Serrano, D P, and Valverde, J L. 1994. "Deactivation kinetics of para-selective toluene disproportionation over modified ZSM-5". United States. https://doi.org/10.1021/ie00025a005.
@article{osti_5324455,
title = {Deactivation kinetics of para-selective toluene disproportionation over modified ZSM-5},
author = {Uguina, M A and Sotelo, J L and Serrano, D P and Valverde, J L},
abstractNote = {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.},
doi = {10.1021/ie00025a005},
url = {https://www.osti.gov/biblio/5324455}, journal = {Industrial and Engineering Chemistry Research; (United States)},
issn = {0888-5885},
number = ,
volume = 33:1,
place = {United States},
year = {Sat Jan 01 00:00:00 EST 1994},
month = {Sat Jan 01 00:00:00 EST 1994}
}