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KATALITIČKA OKSIDACIJA POLIFENOLA UZ Cu-MCM-22 I Cu-MCM-36 ZEOLITNE KATALIZATORE

The olive oil processing industry consumes high quantities of fresh water and produces highly polluted olive oil mill wastewater (OOMW) where polyphenols such as tyrosol and phenolic acids are commonly found. These compounds makes the OOMW phytotoxic and biorefractory in nature and unsusceptible to the direct biological treatment. Catalytic wet peroxide oxidation process (CWPO) is one of the methods that can be used for reducing the toxicity of OOMW in practice under mild conditions with low energy consumption. Large pore microporous MCM-22 and mesoporous MCM-36 zeolite have already been successfully tested as catalysts in a number of reactions [1]. By incorporating an active transition metal cation such as copper, these zeolites should exhibit good catalytic behavior in the oxidation of the large phenolic molecules. A series of layered MCM-22 precursors with SiO2/Al2O3 ratios of 30, 50 and 100 were synthesized in autoclaves with rotation mode and calcined to produce microporous Na-MCM-22 zeolites. Mesoporous Na-MCM-36 zeolites were prepared of by swelling and pillaring of layered MCM-22 precursors. Copper was introduced in the zeolite by postsynthesis ion exchange of the MCM-22 and MCM-36 zeolites proton forms with copper nitrate solutions. The synthesized catalysts were characterized by N2 physisorption, XRD, SEM, TEM, TPD-CO2 and FTIR-Pyridine desorption. The successful structural conversion of the microporous MCM-22 to a mesoporous MCM-36 material was confirmed by XRD resulting in the significant increase in the specific surface area and pore volume. In this study, the influence of SiO2/Al2O3 ratio and metal content in the parent zeolite catalysts on their physical, chemical and catalytic properties was investigated. The activity and stability of prepared catalysts was tested in the catalytic wet peroxide oxidation of model olive oil mill wastewater containing tyrosol, 4-hydroxyphenylacetic, caffeic, vanillic, p-coumaric and t-cinnamic acids. The oxidation reactions were carried out in a batch reactor at different temperatures, catalyst loadings and initial concentrations of hydrogen peroxide. During the reactions the content of polyphenols and hydrogen peroxide was monitored. The stability of the catalysts was evaluated by comparison of the fresh and spent catalysts, as well as by monitoring the extent of copper leaching into the reaction mixture. References: [1] M. Käldström, N. Kumar, T. Heikkilä, D.Y. Murzin, Appl. Cat. A-Gen. 397 (2011) 13–21.

catalytic oxidation; polyphenols; Cu-MCM-22; Cu-MCM-36

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