Kinetic study of xylene isomerization reaction with Mo-Pt @ZSM5 catalyst

Kazemi, Monire; Emami Meibodi, Majid; Esmaeili-Faraj, Seyyed Hamid

Kinetic study of xylene isomerization reaction with Mo-Pt @ZSM5 catalyst

Document Type : Original Research

Authors

M. Kazemi ¹

M. Emami Meibodi ²

S. H. Esmaeili-Faraj ³

¹ Department of Chemical Engineering,Faculty of Engineering,Ardakan University,P.O. Box 184, Ardakan, Iran

² Department of Chemical Engineering,Faculty of Engineering,Ardakan University,P.O. Box 184, Ardakan, Iran..

³ Assistant ProfessorDepartment of Material and Chemical Engineering,Shahrood University of Technology,Shahrood, Iran, 3619995161

Abstract

Research subject:

The kinetics of xylene isomerization reaction on Mo-Pt @ZSM5 catalyst has not been investigated so far. In this research, the single reversible reaction of meta-xylene to para-xylene has been studied to model this process. Considering that the feed of the industrial unit has only small amounts of non-xylene compounds, it seems reasonable regardless of other reactions and the results of this research also confirm it.

Research approach:

The desired reaction was carried out in the gas phase and constant temperatures of 375 ^oC and 378 ^oC on Mo-Pt @ZSM5 catalyst. The feed is taken from an industrial unit. In each test, the temperature is considered constant. In this research, in order to obtain a simple model, only the reversible reaction of meta-xylene to para-xylene is considered. The forward speed constant is considered as an adjustable parameter, and the backward reaction speed constant is calculated from the (meta-xylene)-(para-xylene) equilibrium constant reported in the literature. Since other reactions are neglected, the total mole fraction of meta-xylene and para-xylene is assumed to be constant and equal to their sum in the feed, and the mole fraction of ortho-xylene is calculated from the (meta-xylene)-(ortho-xylene) equilibrium constant reported in the literature. Using the mass balance and performance equation of the packed column as well as Ergun's equation to estimate the pressure changes along the column, a suitable differential equation system was proposed in this research and solved numerically using the ode45 function in MATLAB.

Main results: both the experimental data and the simulation results with the Aspen HYSYS software show that the temperature has little effect on the obtained results in the investigated temperature range. The optimal value of the reaction rate constant of metaxylene to paraxylene for the forward reaction is 1340 cm³ of product per gram of catalyst per hour. For the reverse reaction, it is obtained from the equilibrium constant data in terms of temperature. The results and the proposed simple kinetic model give a good prediction of the experimental data.

Keywords

Xylene

isomerization

Catalyst

Kinetics

Modeling

Subjects

metalic

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