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Introduction of iodine into zeolite X exchanged with Ag, Zn or Cu

Unique three dimensional framework structure of zeolites with channels, cavities and mobile cation, enables the synthesis of various nanocomposite material of special properties. In this work we have used direct synthesis of Me-iodide via gas phase as follows: after complete ion exchange Na+ ions from zeolite X with Ag+, Zn2+ or Cu2+ cations from solution, comes vacuum dehydratation of such ion exchanged zeolite (4 h at 270°C), introduction of iodine into zeolite by gas phase diffusion also in vacuum (starting pressure was less than 10 Pa in sealed glass cuvette) at 210°C for 24 h. Finally, samples were washed in absolute ethanol in order to remove iodine molecules from surface of the crystals. Calculated initial pressure of I2 vapor in cuvette at 210°C was 0.8 MPa. Characterization of the samples was made using several techniques such as FTIR and FT Raman spectroscopy, differential thermo-gravimetry (DTG) and X– ray diffraction (XRD). After treatment with iodine vapor, Raman spectra show that small amounts (less than in zeolite A under the same conditions of preparation) elemental iodine is present in all 4 cases (NaZX, AgZX, ZnZX, CuZX). Also the absence of the shifting of the structural bands in FTIR spectra indicates that there is not distortion of the zeolite X framework. Similarly to the Raman spectra, DTG curves confirm the formation of the metal-iodide particles in all 4 samples. On the contrary, diffractogram of the CuZX show only peaks of the Cu(OH)2, but there is not change in crystal morphology after ion exchange.

Iodine; zeolite X; AgI; ion-exchange

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