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Speciation and siting of divalent transition metal ions in silicon-rich zeolites. An FTIR study

Rok: 2019

Druh publikace: článek v odborném periodiku

Název zdroje: Pure and Applied Chemistry

Název nakladatele: Walter de Gruyter GmbH & Co. KG

Místo vydání: Berlin

Strana od-do: 1721-1732

Tituly:

Jazyk	Název	Abstrakt	Klíčová slova
cze	Speciace a lokacedivalentních iontů přechodných kovů v Si bohatých zeolitech. FTIR studie	FTIR metoda byla použita ke stanovení typů a umístění iontů přechodných kovů v matrici zeolitů bohatých na Si.	FTIR; zeolit; přechodný kov; speciace
eng	Speciation and siting of divalent transition metal ions in silicon-rich zeolites. An FTIR study	Speciation and location of Co2+, Mn2+ and NP2+ in the extraframework positions of the dehydrated zeolite matrix of ferrierite structure were studied in detail using FTIR spectroscopy of antisymmetric T-O-T vibrations of the zeolite framework. Me2+-ferrierites were prepared by the ion exchange of the NH4- and Nazeolite forms and by impregnation of the NH4 form. Bare Me2+ occupies all three known cationic sites in dehydrated cationic zeolite. The wavenumbers of bands of individual cations in individual sites were identified. At low Me2+. loadings (Me2+/Al < 0.15), Me2+ replaces two protonic sites and exclusively bare Me2+ is present in dehydrated samples. Sets of such samples were employed for the estimation of extinction coefficients of Co2+, Mn2+ and Ni2+ in cationic sites. These coefficients differ for individual cations but are the same for a cation at different sites. Ion exchange to the NH4 form allows preparation of samples with maximum possible loading of bare Me2+ only for Co2+. In the case of Mn2+, exchange to the Na-parent zeolite or impregnation is required for this purpose while samples with maximum loading by bare Ni2+ can be prepared only by impregnation.	Bronsted acid; cobalt; infrared; manganese; nickel; SSC-2018; transition-metal catalysis; zeolites

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