Modelling of Selective NO x Reduction on Ce/In-Promoted Sulfated Zirconia Catalysts

Abstract

Abstract Various pseudohomogeneous models for the selective catalytic reduction of NO x by methane were developed by considering reaction schemes and kinetic mechanism. The models were applied to predict the performance of Ce/In-promoted sulfated zirconia catalysts in a wide temperature range from 300 to 700 °C in a fixed bed reactor assuming plug-flow. A nonlinear kinetic model fits the experimental data better than a simple linear model. The mass balance differential equations were solved numerically. The model parameters were estimated by the Simplex-method of Nelder–Mead with a fourth order Runge–Kutta–Merson-method. The finally chosen model is better suited for the prediction of the In-free catalysts than for the mixed oxide catalysts or the Ce-free catalysts. The model suggests that CO formed in the process plays no role in the reduction of NO by CH4. This was confirmed by experimental evidence. The investigated Ce/In zirconia system was better suited for NO reduction by CH4 than those published previously.