Parametric sensitivity and runaway in fixed-bed catalytic reactors

Abstract

The sensitivity behavior of fixed-bed catalytic reactors is examined using a heterogeneous one-dimensional plug-flow model, for the case of n-th order irreversible reactions. A novel sensitivity criterion, based on the occurrence of a maximum in the value of the normalized sensitivity of the particle temperature with respect to any of the input parameters of the model, is developed. The intrinsic nature of the proposed criterion allows the definition of a generalized sensitivity region of reactor behavior in the relevant parameter space. The boundaries of the sensitivity region for various values of the involved physicochemical parameters are reported. These are found to be in good agreement with those previously calculated using the classical geometrical criterion, based on the occurrence of a positive second-order derivative, before the hot-spot, in the particle temperature vs. conversion profile. The importance of transport limitations on the sensitivity behavior of catalytic reactors is confirmed by comparison with experimental data available in the literature.