engleski

Influence of Si/Al ratios on the properties of copper bearing zeolites with different framework types

Several copper containing zeolite based catalysts with different initial Si/Al and different zeolite support (types MCM-22, FAU, BETA) were synthesized or prepared from commercial precursors in a powdered and pelleted form via a direct hydrothermal synthesis and ion exchange method, and then subsequently characterized for the evaluation of their chemical, surface and catalytic properties. The characterization of the zeolites, which included the analysis of their morphological and acid-base properties, was performed by using various techniques such as the N2 physisorption, Pyridine-FTIR, XRD, SEM-EDAX and TEM. The activity and stability of the prepared catalysts were tested in the catalytic screening in a catalytic wet peroxide oxidation of the model polyphenolic wastewater. The obtained results provided an insight into the cause-and-effect relationship between the silica to alumina ratio and its direct effect on the acidity and basicity of the prepared zeolites, as well as the indirect one on their morphology, textural and surface properties of both the parent zeolite and active metal component. The use of active catalysts resulted in successfully operating the process under mild conditions with low energy consumption. It was found that the copper and iron containing catalysts showed promising activity, while the stability of the active metal component still is and remains a challenge to obtain.

acidity ; catalytic wet peroxide oxidation ; morphology ; phenolic wastewater ; surface properties ; transition metals ; zeolites

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