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Abstract:ITH-type germanosilicate, Cu- and Co-containing ITH-zeotype materials, were synthesized by the hydrothermal method in the presence of an organic structure-directing agent, N,N,N',N'-tetramethyl-1,6-hexanediamine. The effects of reaction compositions, including the molar ratios of SiO2/GeO2, SiO2/H2O, and MeO/SiO2 (Me = Cu and Co transition atoms) on the synthesis of the pure product were investigated. The synthesized samples were characterized by powder and single-crystal X-ray diffractions, scanning electron microscopy, inductively coupled plasma (ICP) analysis, energy dispersive spectrometry, thermogravimetric analysis, UV-Vis diffuse reflectance spectrum (DRS) measurements, X-ray photoelectron spectroscopy, and N-2 adsorption and desorption analysis. The results reveal that the concentration of H2O in the reaction mixture has an important impact on the synthesis of pure ITH-type zeolite. The framework's Si/Ge ratio is slightly changed from 3.1 to 3.9 when the initial SiO2/GeO2 molar ratio is increased from 0.8 to 10. Structure refinement results show that the Ge atoms preferably occupy sites in the double-four ring units. Cu and Co atoms have been introduced for the first time into ITH-type materials. The trace amounts of amorphous Cu-and Co-compounds in the resulting materials can be readily detected by backscattered electron imaging, so that pure samples can be selected for ICP and UV-Vis DRS measurements.

Volume:51

Issue:10

Translation or Not:no