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Preparation and testing of cordierite monolithic catalysts for oxidation of aromatic volatile organic compounds

This work reports the results of catalytic oxidation of aromatic volatile organic compounds (VOCs). A gaseous mixture of benzene, toluene, ethylbenzene, and o-xylene (BTEX) in nitrogen was used as representative of VOCs. Reactions were carried out in a monolithic reactor at different temperatures, with a constant initial concentration of reactants and a constant ratio of BTEX and oxidant (synthetic air). Analysis of the oxidation products was carried out on-line before and after reaction using gas chromatography. The work involves the preparation of catalysts and their application on an inert cordierite monolithic carrier, using different combinations of mixed manganese oxides (manganese with copper, iron, and nickel) and palladium as a representative of noble metals. The prepared cordierite monolithic catalysts showed great mechanical stability and high performance regarding oxidation of the mixture of aromatic compounds. High conversion values (90 %) of all components of the mixture were achieved at temperatures below 200 ⁰C, depending on the chemical composition of the catalytic layer. A comparison with the activity of a commercial monolithic catalyst (Purelyst PH-304), which contains Pt and Pd as catalytically active components, using toluene as a model component. A comparison of the prepared manganese oxides showed that MnFeOx and MnCuOx had the best catalytic activity. When Pd was used in combination with MnFeOx in a form of a single monolith, where Pd was applied to ¼ of the overall monolith length and MnFeOx to ¾ of overall length, achieved 90 % conversions (T90) were up to 20 ⁰C lower when compared with the same MnFeOx monolithic catalysts without Pd. Based on the comparison of the prepared ceramic monolithic catalysts with a commercial catalyst and because the comparison was made only based on toluene conversion, it was concluded that the prepared catalysts can be considered as alternatives to commercial monolithic catalysts by introducing a low concentration of Pd.

catalytic oxidation ; monolithic catalysts ; volatile organic compounds ; manganese oxides

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