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Transalkylation of 1,3,5-triethylbenzene (TEB) with ethylbenzene (EB) has been studied over ZSM-5 zeolite using a riser simulator reactor with respect to optimizing DEB yield. The reaction temperature was varied from 350 to 500 °C with contact time ranging from 3 to 15 s to report on the effect of reaction conditions on TEB conversion, DEB selectivity and isomerization of TEB. The transalkylation of TEB with EB was compared with the reactions of pure 1,3,5-TEB and EB (disproportionation, isomerization and cracking). A synergistic effect was observed on the conversion of 1,3,5-TEB and DEB yield. The 1,3,5-TEB conversion increased from 40% to 50% with simultaneous increase in the DEB selectivity from 17% to 36% in transalkylation reaction (EB + 1,3,5-TEB) as compared with the reaction of pure 1,3,5-TEB. It was found that pure 1,3,5-TEB underwent cracking reaction to produce DEB and EB. The isomerization of 1,3,5-TEB was more active at low temperature while cracking was more active at high temperature. The temperature of 350 °C was observed as the optimum for production of maximum amount of DEB. Kinetic parameters for the disappearance of 1,3,5-TEB during its transformation reaction via cracking and isomerization pathways were calculated using the catalyst activity decay function based on time-on-stream (TOS). The apparent activation energies decrease in order Esecondary cracking > Eprimary racking > Eisomerization for ZSM-5 catalysts. |
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