Comparison of reverse flow and counter-current reactors in case of selective catalytic reduction of NOx

The paper is focused on the comparison of the reverse flow reactor (RFR) and of the counter-current reactor (CCR) operation, focusing the attention on the interaction between transport phenomena and chemical reactions, as well as on the analysis of the dynamic behavior. A heterogeneous mathematical model was used in order to investigate the performance of both reactor configurations. The role of the thermal balance was stressed. Auto-thermal reactor operation was obtained even when low temperature gas is fed to the reactor. Temperature profiles, reactants conversion inside the apparatus and the response to perturbation in the feeding flow have been used as criteria for comparison. Numerical simulations revealed that RFR has an asymptotic behavior coincident to the CCR, which is technically simpler to be realized. However the domain where the counter-current reactor can be used as a limiting case of the RFR depends on the internal heat transfer coefficient, switching time, flow condition and reactor geometry.