Numerical Investigation on the Intraphase and Interphase Mass Transfer Limitations for NH 3 -SCR over Cu-ZSM-5.

A systematic modeling approach was scrutinized to develop a kinetic model and a novel monolith channel geometry was designed for NH₃ selective catalytic reduction (NH₃-SCR) over Cu-ZSM-5. The redox characteristic of Cu-based catalysts and the variations of NH₃, NO_x concentration, and NO_x conversion along the axis in porous media channels were studied. The relative pressure drop in different channels, the variations of NH₃ and NO_x conversion efficiency were analyzed. The model mainly considers NH₃ adsorption and desorption, NH₃ oxidation, NO oxidation, and NO_x reduction. The results showed that the model could accurately predict the NH₃-SCR reaction. In addition, it was found that the Cu-based zeolite catalyst had poor low-temperature catalytic performance and good high-temperature activity. Moreover, the catalytic reaction of NH₃-SCR was mainly concentrated in the upper part of the reactor. In addition, the hexagonal channel could effectively improve the diffusion rate of gas reactants to the catalyst wall, reduce the pressure drop and improve the catalytic conversion efficiencies of NH₃ and NO_x. [ABSTRACT FROM AUTHOR]