Cross-Flow Naphtha Reforming in Stacked-Bed Radial Reactors with Continuous Solid Circulation: Catalyst Deactivation and Solid Circulation between Reactors

Abstract

A naphtha-reforming reactor system, consisting of four stacked-bed reactors with cross-flow of gas and circulation of catalyst, was simulated. Commercial and micropilot plant data were used to adjust the kinetics and deactivation constants, based on previous results obtained in fixed-bed operations with another catalyst. The simulation of radial commercial reactors was performed using mixing zones for the intervessel solid transfer and a second zone through which the solids move downward and within which reactions take place. The mass and energy differential equations were solved in the radial and axial direction point by point, using the Runge–Kutta–Fehlberg (RKF) numerical method. The effects of solid mixing on catalyst profiles of coke were determined in a cold model. Sequential deactivation and partial mixing tests were performed to verify their effects on catalyst activities. Spent catalysts were characterized and tested under different operating conditions. The feed and reformate were characterized using an extended PIONA-MS method to obtain additional information about the isomers for different carbon numbers. Temperature, yields, activities and pressure are predicted by the model and compared to commercial data. The results show the importance of considering the effect of solid mixing, the two-dimensional pressure-drop temperature, and the variation in catalyst activity across and along the reactors.