Modeling of ZnZSM-5 deactivation during liquefied petroleum gas catalytic cracking in the presence of steam

Abstract

The purpose of this work was to propose a kinetic model for liquefied petroleum gas (LPG) catalytic cracking over modified ZSM-5. For the catalytic cracking of LPG, the mathematical modeling based on a complex reaction methodology was proposed. One of the major issues associated with the catalytic cracking reaction is the activity decrement during time on stream. Coke deposition has a significant contribution in catalyst deactivation. In this study, steam was injected accompanied with feed to decrease the coke accumulated on catalyst surface and reduce the deactivation rate. However, steam dilution led to higher dealumination rate and sintering which results in activity reduction. Moreover, the main reaction kinetic model, a novel deactivation one was presented included various coke formation, sintering, dealumination and steam effect were studied in detail. The experiments were done at 565 to 600 to 635 °C and atmospheric pressure with the steam ratios of 1.5, 2.2 and without steam. The kinetic parameters optimized from deactivation were described as Arrhenius equation. The results of model calculation are in appropriate agreement with experimental data of 7.81% RMS.