The study on Cu-ZK-5 catalyst of copper content regulation and anti-propylene poisoning mechanism in NH3-SCR reaction

Cu-ZK-5 catalysts have been attempted to utilize as NH3-SCR because they have small pores and eight-membered ring structures. In this work, Cu-ZK-5 catalysts with different copper contents were investigated. It was found that the Cu7.55-ZK-5 catalyst showed excellent activity and resistance to propylene poisoning for NH3-SCR. When the copper content is too low, the number of active copper species is less, and the activity is poor. When the copper content is too high, CuOx species will be generated to destroy the structure of the molecular sieve and affect the activity, which manifested that the optimal copper loading of Cu-ZK-5 catalyst possesses more Cu2+ species improving the activity for NH3-SCR. Furthermore, the presence of propylene on Cu7.55-ZK-5 catalyst had little impact on the low-temperature catalytic performance and exhibited excellent propylene resistance at medium and high temperatures. The influence on the low-temperature catalytic performance of the Cu-ZK-5 catalyst is mainly since C3H6 has competitive adsorption with NO on the surface of Cu-ZK-5, which may be the main reason for slightly reducing the NOx conversion of Cu-ZK-5 catalyst.