Tuning the Chemical State of Silver on Ag–Mn Catalysts to Enhance the Ozone Decomposition Performance
Xiaotong Li, Jinzhu Ma, Hong He
Abstract
Ag–Mn catalysts with excellent water resistance and ozone decomposition activity were successfully synthesized by simple precipitation and impregnation methods. Under a relative humidity of 65% and space velocity of 840,000 h–1, the 6%Ag/α-Mn2O3-I catalyst showed 99% conversion of 40 ppm O3 after 6 h, which was far superior to the performance of the 6%AgMnOx-C (49%), 6%Ag/MnCO3-I (32%), and α-Mn2O3 (5%) catalysts. Physicochemical characterization indicated that the chemical state of Ag on the Ag–Mn catalysts determined the O3 decomposition activity of the catalysts. The Ag species on the 6%Ag/α-Mn2O3-I catalyst were mainly metallic silver nanoparticles (Agn0), which exhibited much better ozone decomposition performance than the Ag1.8Mn8O16 and oxidized silver clusters (Agnδ+) existing on the 6%Ag/MnCO3-I and 6%AgMnOx-C catalysts. The 6%Ag/α-Mn2O3-I catalyst still had above 85% ozone conversion after 60 h under a relative humidity of 65% and space velocity of 840,000 h–1. The slight deactivation of the catalyst was ascribed to the oxidation of Agn0, and its activity could be completely recovered by treatment at 350 °C under an N2 atmosphere, which indicated that it is a promising catalyst for ozone decomposition. This research provides guidance for the subsequent development of Ag–Mn catalysts for ozone decomposition with high activity.