Kinetic Study of Xylene Isomerization Reaction and Ethylbenzene Conversion on Mo-Pt@ZSM۵ Catalyst

This research theoretically studies xylene isomerization on the Mo-Pt@ZSM۵ catalyst. The inlet stream composition is similar to the actual current in the petrochemical unit. The empirical data are gas-phase compositions in the temperature range ۳۷۰ oC to ۴۰۰ oC in the catalytic reactor. Two suitable kinetic models were proposed for catalytic reactions, one incorporating adsorption terms and the other mass transfer coefficients into the rate equations. The model's predictions are acceptable compared to the laboratory error of about ۱%. Using a genetic algorithm, surface adsorption equilibrium constants appearing in the denominator of the first model were evaluated for metaxylene as Km = ۰.۰۰۱۲, and for ethylbenzene as Keb = ۰.۰۳۷۹. In the second model, the meta and ortho mass transfer coefficients are equal, and βM = ۱.۵۱۴×۱۰۶ cm۳/(gcat.h), and βEB = ۶.۸۴۷×۱۰۵ cm۳/(gcat.h), ​are derived using a genetic algorithm. The rate constants in both models are k۳ = ۰.۰۵۶۱ molei/(gcat.h), k۹ = ۰.۰۲۸۵ molei/(gcat.h), and Arrhenius constants are k۰۷ = ۱۴۱۷ molei/(gcat.h), E۷ = ۳۵۵۹۲ J/mol, k۰۱۱ = ۳.۱۵۶×۱۰۷ molei/(gcat.h), and E۱۱ = ۱.۲۸۳×۱۰۵ J/mol. The results show that, as expected, the metaxylene and orthoxylene decrease along the reactor, and the concentration of paraxylene increases. The results of the second model showed that the mass transfer resistance can be ignored for xylenes. But, in the case of ethylbenzene, mass transfer resistance has a greater effect. Therefore, both models have the same precision; however, they provide different information about the adsorption and mass transfer of components.

کلیدواژه ها:

Isomerization ، xylene ، Conversion ، Ethylbenzene ، catalyst