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Implementation of Fe and Ag cations in the mordenite-type framework

Mordenite belongs to the so-called “big five” zeolites, which are extensively applied in the industry as catalysts.1 Important issue in catalysis efficiency is the number of active sites (i.e. Lewis and Brønsted acid sites). Numerous studies have shown that the catalytic properties of metal exchanged zeolites are determined by the location and valence state of metal cation and coordination in the zeolite lattice, as well as by the metal content. Mono- and bimetallic systems of Ag, Fe, and Ag–Fe were prepared by the wet impregnation of the H- form of mordenite (Si/Al=11) and consecutive thermal treatment. PXRD patterns show that after all post-synthesis treatments there is no significant influence on the crystallinity of the samples and the only detected phase was mordenite. The results from catalyst characterization by SEM/EDS have shown preserved morphology after wet impregnation and that a certain amount of metals was incorporated into mordenite crystals. The more precise composition of the samples was determined by FAAS, but the technique is not able to detect the position and coordination of the metal cation in the framework. UV–Vis spectroscopy was applied to identify the silver and iron complex species, due to their specific behavior under the light. Also, their photostability was tested by exposing the samples to radiation in the wavelength range of 200 to 1000 nm.

zeolite ; mordenite ; AAS

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