An efficient and robust method for numerical analysis of a dead zone in catalyst particle and packed bed reactor

Abstract

AbstractZones without reactants inside a catalyst pellet, the so‐called dead zones (DZs), have been reported in the case of catalysis and biocatalysis, two processes of fundamental importance. The presence of the DZ results from diffusional transport limitations when an apparent reaction order is in the range: −1 to 1. The formation of a DZ reduces the effectiveness of a catalyst and affects packed bed reactor productivity. For a simple reaction kinetic model, the width of a DZ inside a pellet can be predicted analytically by solving the appropriate differential mass balance model. However, for more complex kinetic models, the analytical solution is unknown, and a DZ position can be established only by applying a numerical method. The problem with the DZ appearance belongs to problems with moving boundaries. Its solution requires the application of a particular numerical procedure and a relatively long CPU time. In this work, a simple, high‐speed numerical method for the calculation of a DZ position inside a pellet is proposed. The proposed method, combined with the orthogonal collocation on finite elements can be applied to analyze a packed bed reactor operation.