Chemical Engineering Science, Vol.54, No.20, 4449-4457, 1999
Effect of diffusion and adsorption-desorption on periodic operation performance of NO-CO reaction over supported noble metal catalysts
Effects of intrapellet diffusion and of adsorption along a plug-flow reactor on periodic operation performance of NO-CO reaction over Pt/Al2O3 and Rh/Al2O3 were investigated by reaction experiments and by model calculations. The model calculation for the effect of intrapellet diffusion on the time-averaged conversion of NO showed that the effect was significant under periodic operation at cycling periods longer than several tens of seconds in the case of strong adsorption even when it had no significant effects on steady-state performance. A two-stage catalyst bed which consisted of Pt/Al2O3 at the inlet- and Rh/Al2O3 at the outlet-side attained a higher time-averaged conversion of NO than a similar one but with the reverse placement. Model calculations for the effect of adsorption-desorption along the catalyst bed showed that the result described was caused by deformation of concentration cycling pattern due to strong adsorption of NO and CO. Calculated breakthrough curves could simulate the experimental ones quite satisfactorily.