Modelling of non‐stationary ammonia synthesis kinetics over an iron catalyst II. Modelling results of forced feed composition in periodic operation and for step‐changes

Simulation using the two‐site dissociative adsorption model given in Part 1 of this study fails to predict the improvement observed in the time‐average rate under cyclic operation even though it does recreate the observed steady‐state and transient response features following a step‐change in the feed composition. The improvement in the time‐average cycling rate is probably due to the diffusion of nitrogen into the bulk‐phase of the iron catalyst, which is a metastable nitrogen? Iron system under forced feed composition cycling. A two‐site adsorption model, modified to take account of the inventory of nitrogen in the bulk‐phase of the iron catalyst, is presented. This model predicts the improvements in ammonia production observed under periodic operation.