Dynamic Simulation and Sensivity Analysis of Fluidized Bed Methanol Reactor with Deactivated Catalyst

Frequently the activity of fresh catalyst changes with time in use. The decrease or increases of the catalyst activity with time during the course of reaction forces the system to an unsteady state operation ([1], [2], [3], [4] and [5]). One of these catalysts is the copper/zinc oxide catalyst, which is industrially used for methanol production. The activity of copper/zinc oxide catalyst declines so that methanol production decreases as time progresses. This catalyst is used in the reactor of the methanol reactor [6]. The activity of copper/zinc oxide catalyst declines with time during the course of reactions and the methanol production decreases as time progresses ([6], [7], and [8]). In order to maintain the methanol production at the suitable rate, extra 2 CO is added to the feed as time goes on [6]. Extra 2 CO in the system in one hand will enhance the rate while on the other hand will occupy active sites and causing deactivation of catalyst, hence an optimum amount of 2 CO in the system should be maintained. Recently, a significant amount of research has been directed toward a better understanding of fundamental processes involved in deactivation of this catalyst. In this work, the mechanistic rate of deactivation of catalyst developed by Rahimpour et. al. ([1], [3]) have been used in the model development of an fluidized bed methanol reactor. A detailed dynamic two-phase model developed by Mowla and Rahimpour [9] described by a set of partial differential and algebraic equations (PDAEs) was extended for fluidized bed reactor and solved to predict the behavior of the deactivation processes in the methanol fluidized bed reactor. In this development active site balance on surface of the catalyst is used to obtain selective activity of catalyst. This model describes the dynamic behavior of the active sites of a deactivated commercial copper zinc oxide catalyst. In order to validate the dynamic model for the fluidized bed reactor, some dynamic simulations were performed using operating conditions and plant characteristics of Shiraz Petrochemical Complex for a period of 2 years. The good agreement between the dynamic simulation results and the plant data shows the validity of the model and confirmed the idea that CO and 2 CO are