Toluene removal by a DBD-type plasma combined with metal oxides catalysts supported by nickel foam

The performance on toluene removal in a dielectric barrier discharge (DBD) type plasma system under different background gases, including N2, Ar, N2/Ar, and N2/O2 was studied at room temperature and atmospheric pressure. For comparison, another laboratory-scale plasma-catalysis system was set up and four kinds of metal oxides, i.e., copper oxide, iron oxide, cobalt oxide, and manganese oxide supported on alumina/nickel foam (NF), were used as catalysts. The reaction mechanism and dynamics analysis on toluene removal were suggested. In addition, the characterization of the catalysts was performed by BET, XRD, SEM, FT-IR, and EDS. It has been found that adding argon in the background gas could improve the toluene removal efficiency significantly in the plasma system. Combining plasma with catalyst in situ could improve the toluene removal efficiency, increase the carbon dioxide selectivity and suppress byproducts formation. In addition, manganese oxide/alumina/NF was confirmed as the most effective catalyst for toluene removal. The XRD and SEM results showed that the proportion of metal oxide increased while aluminate decreased after plasma application. The granularity of the grain on the catalyst surface became smaller and the distribution became more uniform after discharge. The results of FT-IR and EDS suggested that some organic compounds deposited on the catalysts after plasma reaction.