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Solid-state ion exchange of CoCl2 center dot 6H(2)O into NH4+-Beta zeolite: Pathway analysis
Authors: Essid Safaa | Ayari Faouzi | Bulánek Roman | Vaculík Jan | Asedegbega-Nieto Esther | Mhamdi Mourad | Delahay Gerard | Ghorbel Abdelhamid
Year: 2018
Type of publication: článek v odborném periodiku
Name of source: Microporous and Mesoporous Materials
Publisher name: Elsevier Science BV
Place: Amsterdam
Page from-to: 218-229
Titles:
Language Name Abstract Keywords
cze Pevnofázová iontová výměna center CoCl2.6H2O do NH4+-Beta zeolitu: Analýza průběhu Iontová výměna center CoCl.6H2O do NH4+-Beta zeolitu v pevn fázi byla studována v teplotním rozsahu 30 - 500 °C a izotermně při 500 °C po 12 hodin. V přítomnosti zeolitu TG-MS analýza prokázala, že hydratace/dehydratace soli je vratný proces. chlorid kobaltu; UV/Vis DRS; TG/DTG; Racah parametr; iontová výměna v pevné fázi
eng Solid-state ion exchange of CoCl2 center dot 6H(2)O into NH4+-Beta zeolite: Pathway analysis Solid-state ion exchange of CoCl center dot 6H(2)O into NH4+-Beta zeolite (Co/Al = 1, Si/Al = 12.5) was studied throughout the temperature range of 30-500 degrees C, and isothermally at 500 degrees C for 12 h. In the presence of zeolite, the thermal analysis coupled to mass spectrometry revealed that the hydration/dehydration of the salt is a reversible process. Therefore, the coordination of Co2+ central ion was elucidated by the evaluation of Racah and octahedral ligand-field-splitting parameters, determined from visible diffuse reflectance (DR) spectra recorded between 250 and 350 degrees C. Following the non-isothermal exchange of Co2+ into Beta zeolite between 400 and 500 degrees C, the partially hydrated Co(II) complex occupied, temporarily, alpha, beta, and gamma-sites, while epsilon-site is less-accessible to Co2+ ions on the basis of the quantitative study performed by visible DR spectroscopy. Nevertheless, following the isothermal exchange at 500 degrees C, Co2+ ions occupied, definitively, alpha, beta, and gamma-sites through a slow migration, extended up to 12 h. Using Infrared spectroscopy upon desorption of C O at -196 degrees C, we were able to reveal the presence of [Co(III)O](+) species. Nonetheless, by coupling both Infrared and DR results, we were able to identify, on one hand, the specific bands (in v(C O) region) relative to each Co2+ ion type and to reveal, on the other hand, that the rate of Co2+ ions mobility during isothermal exchange increases in the following order: gamma-type < beta-type < alpha-type. Cobalt chloride; UV/Vis DRS; TG/DTG; Racah parameter; Solid state ion exchange

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