In situ study of ozone and hybrid plasma Ag–Al catalysts for the oxidation of toluene: Evidence of the nature of the active sites

Silver colloids have been prepared by reducing AgNO3 in aqueous solution and embeded in alumina following a sol–gel procedure in the presence of Pluronic 84 ((EO)19(PO)39(EO)19), as surfactant. Plasma-catalytic experiments aimed at the mineralization of toluene showed that the selectivity to CO2 was significantly increased in the presence of Ag catalysts compared with results obtained using the plasma alone. In-situ studies of the ozone interaction with catalysts provide an insight into the nature of the active sites of supported silver colloids for mineralization reactions. It is noticeable that when ozone is chemisorbed on embedded Ag colloidal catalysts no change in the silver oxidation state or size is found. The population of the chemisorbed species is higher at lower temperatures, where the non-selective decomposition of ozone is smaller. The catalysts exhibit high stability, preserving the structural and textural properties after the catalytic tests, that is indeed very important in the presence of ozone.

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► Silver colloids embedded in alumina following a sol–gel procedure in the presence of Pluronic 84 are stable catalysts in the presence of ozone.
► Plasma-catalytic experiments in the total oxidation of toluene showed a significantly increased selectivity to CO2 in the presence of Ag embedded colloids.
► In situ studies of the ozone interaction with catalysts provide an insight into the nature of the active sites of supported silver colloids for total oxidation reactions.