Quantum Chemical Study on the Reaction Mechanism of Fast SCR Catalyzed by ZSM-5 Doped with Mn/Co–Al/Ce

Fast selective catalytic reduction (SCR) is regarded as a good choice to improve the SCR denitrification efficiency and reduce the using of catalyst. For a good understanding and further improvement, the investigation on the mechanism of SCR and fast SCR is essential. A four-step catalytic mechanism for SCR and fast SCR catalyzed by ZSM5 doped with Mn/Co–Al/Ce is proposed in this paper, and the catalytic mechanism is studied in detail by using the method of quantum chemistry. Results show that, by using ZSM5–Mn/Co catalyst, the activation energy of fast SCR (83.35/87.55 kJ/mol) is much lower than that of SCR (154.98/219.70 kJ/mol). This indicates that fast SCR has a better catalytic effect and higher denitration efficiency. Moreover, when Al/Ce is added into ZSM5–Mn/Co, the active center Si is replaced by Al/Ce, and the activation energy of fast SCR is further decreased to about 40–60 kJ/mol. This shows that the catalysts for SCR and fast SCR not only relate to the supported transition metal such as Co and Mn, but also highly relate to the activity center such as Al and Ce.