Structural Changes in Manganese Oxides on Zeolite Y in Benzene Oxidation with Ozone and Post-Heat Treatment

MnO_X supported on a zeolite Y catalyst (MnO_X/Y) is widely utilized for the removal of volatile organic compounds (VOCs), providing an understanding of catalyst structural changes and the factors influencing these changes. This study introduces a heat treatment method to recover the catalyst. The efficacy of the treated catalysts in enhancing the oxidation of benzene by ozone was improved. Investigation of the behavior of catalysts prepared from acetate and nitrate precursors revealed a common trend: MnO_X in the catalysts was readily reduced to MnO by intermediate products, acids, aldehydes, and phenols formed during the benzene ozonation process, as evidenced by X-ray absorption fine structure temperature-programmed reduction and in situ Fourier-transform infrared spectroscopy analyses. Heat treatment at 200 °C was found to be insufficient for the restoration of the MnO_X structure, which was attributed to the persistence of acids and hydrocarbons within the catalyst. 500 °C was determined to be more appropriate for the regeneration of the used catalysts, indicating the critical role of the heat treatment conditions in maintaining the effectiveness of the MnO_X/Y catalysts in VOC removal applications. Graphical Abstract: (Figure presented.)