1995 Volume 21 Issue 6 Pages 1133-1139
A model has been developed to represent the deactivation of REY zeolite caused by coke deposition during catalytic cracking of heavy oil obtained from pyrolysis of waste plastics. Coke deposition not only leads to coverage of the acid sites, which contribute to the reaction, but also leads to a decrease in the intracrystalline diffusivity of the zeolite due to the reduction in effective pore opening, resulting in deactivation of the catalyst. In this work, firstly the amount of strong acid sites and the diffusivity of catalysts with different amounts of coke loading were measured, and empirical equations, which represent the relationships between the amount of coke loading and these two values, were obtained. Finally, a model was developed to calculate the transient change of the catalyst activity and the concentration distributions of the components within the reactor by employing the obtained empirical equations. The calculated results agreed well with experimental results. Using this model, it was found that the deactivation rate of the catalyst was reduced under diffusion control conditions, and large catalyst particles could maintain their activity longer than small catalyst particles.