Systematic Procedures for Interpretation and Modeling of Catalyst Deactivation Using Integral Fixed-Bed Reactors

Abstract

The method of decreasing conversion, constant space−time (DCCST) is sometimes used for empirical determination of catalyst decay kinetics in fixed beds. The method of constant conversion, increasing space−time (CCIST) is used infrequently. Although it is well known that these methods are most readily applied to cases in which the deactivation is independent of the composition of the fluid phase, the ease with which they can be misapplied to concentration-dependent cases has not been studied systematically. In this work, the empirical determination of catalyst decay kinetics in fixed beds has been examined by numerical simulation. It has been shown that it is rather easy to generate an invalid concentration-independent decay model, either by fitting a dubious straight line to a limited range of data using the DCCST method or by fitting a good, or even perfect, straight line using the CCIST method. It has also been shown that both methods can, in principle, be used reliably for empirical determination of ca...