Adsorption of VOCs Is a Key Step in Plasma-Catalyst Coupling: The Case of Acetone onto TiO2 vs. CeO2

Abstract

If a number of literature studies point at the positive role of coupling materials with non-thermal plasma, particularly for Volatile Organic Compounds (VOC) removal, most of them focus on the direct plasma-material interaction to understand the coupling. However, a key contribution relies in the VOC–material interaction. Therefore, this study focuses on the adsorption step of targeted VOCs to provide a new insight on plasma–material coupling. The adsorption of acetone, used as probe VOC, is explored on two widespread coupling materials: TiO2 and CeO2. First, their behaviors are compared regarding acetone uptake. This process is reactive and creates other organic species than acetone on both surfaces. Second, the metal oxide behaviors are compared regarding ozone uptake. Interestingly, under typical VOC treatment configuration, i.e., with organics on their surfaces, ozone uptake is driven by the adsorbed organics, not directly by the metal oxides anymore. Finally, the ozonation of both materials, preliminary exposed to acetone, is explored through the evolution of the adsorbed organics and the corresponding mineralization, i.e., CO and CO2 formation. It evidences that the reactive adsorption of VOCs plays a key role in making the surface organics ready for an efficient oxidation and mineralization under post-plasma exposure.