Engineering Subnanometric Electronic Interaction between Ru and Mn in Zeolite Boosts Catalytic Oxidation of Dichloromethane

Abstract

Designing catalysts with both activity and stability remains a grand challenge for the removal of chlorinated volatile organic compounds (CVOCs) by catalytic oxidation. Herein, the Ru–Mn subnanometric species encapsulated in ZSM-5 zeolite (RuMn@Z) was synthesized. It shows that the 90% conversion of dichloromethane is as low as 320 °C, which is significantly lower than that of Ru@Z (350 °C) and the impregnation catalyst (RuMn/Z, 355 °C). Importantly, the RuMn@Z catalyst exhibits excellent high-temperature resistance (800 °C for 10 h), water resistance, long-term stability, and cyclic stability. Different from the RuMn/Z with nanoscale metal interaction, Ru and Mn species in RuMn@Z have strong electronic interaction on the subnanometric scale due to the confinement effect of zeolite. As the electronic structure regulator, the Mn species keeps the Ru species in an electron-deficient state through the Ru–O–Mn bonds, which effectively activates lattice oxygen species and molecular oxygen to participate in the reaction. Moreover, the confinement effect also makes the acid tightly coupled with the redox site, which promotes the rapid conversion of dechlorination products, formates, and other intermediate products. Therefore, this study provides valuable insights into the design of high-performance catalysts for CVOCs removal and other environmental fields.