Adsorption/desorption models: How useful for predicting reaction rates under cyclic operation

A computational study is reported of the behaviour of three catalytic reaction models containing conventional adsorption, desorption, and surface reaction steps under conditions of forced composition cycling in a mixed reactor. The models contained varying degrees of non‐linearity. With long cycle periods, the time‐average rate of reaction asymptotically approached the quasi‐steady state. Time‐average rate behaviour was found to be bounded by the asymptotes of quasi‐steady state rate under slow cycling, and the relaxed steady state under rapid cycling. It is concluded that the approach used until now to model catalytic reactions is very likely inadequate to describe the dynamics of forced cyclic operation observed in a number of experimental systems