Effect and optimization of radial non-uniform porosity catalyst on SCR characteristics based on response surface method

Abstract

Selective catalytic reduction (SCR) system is used to the denitration (de-NOx) of diesel engine exhaust after treatment. In this work, a three-dimensional SCR model with radial non-uniform distribution of catalysts is established to study the pressure drop and de-NOx performance. Firstly, the SCR converter model with uniform catalyst distribution is selected to verify its reliability. Then, the radius R1 and porosity ԑ1 of area 1, radius R2 and porosity ԑ2 of area 2 are selected as single factor variables to study the influence on the SCR system performance. Finally, response surface methodology (RSM) is employed to evaluate and optimize the above single factor parameters affecting de-NOx performance and pressure drop of SCR system. The results showed that the change of ԑ2 had the greatest impact on de-NOx efficiency and pressure drop. The optimum condition for maximum de-NOx efficiency was estimated at the R1 of 50 mm, R2 of 100 mm, porosity ԑ1 of 0.47 and porosity ԑ2 of 0.7. Under these conditions, the de-NOx efficiency by numerical simulation was 80.37 %, which was close to the predicted value (80.68 %), and the pressure drop was 218 Pa, which was close to the predicted value (246 Pa). Compared with the uniform distribution of catalysts, the de-NOx efficiency of the optimal Case of numerical simulation is increased by 3.74 %, and the pressure drop is reduced by 46 Pa. The research can provide theoretical and engineering references for the improvement of SCR catalyst coating process.