The effect of support pretreatment on activity of Ag/SiO2 catalysts in low-temperature CO oxidation

Abstract

Silver supported on silica, prepared by impregnation method, was investigated using TEM, XRD, UV–vis spectroscopy, TPO, H2 TPR and CO TPR methods, and tested in low-temperature CO oxidation. To reveal the role of metal-support interaction, the Ag catalysts based on silica, pre-treated at 500 (SiO2-500) and 900°C (SiO2-900), were compared. Highly dispersed silver particles (1–4nm) were observed for both Ag/SiO2-500 and Ag/SiO2-900 catalysts. The highest amount of active oxidative species was determined for Ag/SiO2-900 catalysts using TPx methods. The high temperature (900°C) pretreatment of silica support is found favorable for formation of silver species active in O2 and CO activation and leads to increasing of catalytic activity in CO oxidation. The defect structure of Ag nanoparticles is a possible reason for high activity in low-temperature CO oxidation.