Unexpected strong toluene chemisorption over Ag/CeO2 catalysts for total toluene oxidation

The effect of Ag content on the sorption properties and toluene removal activity over Ag/CeO2 catalysts is studied. In this paper, the series of Ag/CeO2 catalysts with Ag content from 1 to 10 wt% are prepared by impregnation method and characterized using a complex of methods: low-temperature N-2 adsorption, XRD analysis, TPR-H-2, and TEM-HR. For the first time, the strong toluene chemisorption over Ag-containing species accompanied by total oxidation into CO2 is observed. The correlation between the amount of chemisorbed toluene and Ag loading in the catalysts confirms the toluene chemisorption over Ag species and/or Ag-CeO2 interface. The active surface oxygen of ceria oxidizes chemisorbed toluene. The cooperation of active sites on silver and ceria provides both enhanced chemisorption of toluene and its total oxidation. The total removal of toluene (2000 ppm) was achieved at similar to 140 degrees C over 5Ag/CeO2 and 10Ag/CeO2 catalysts due to both chemisorption and total oxidation of toluene.