Repozytorium Uniwersytetu Jagiellońskiego

Quantitative IR studies of the concentration of Co^{2+} and Co^{3+} sites in zeolites CoZSM-5 and CoFER

Quantitative IR studies of the concentration of ...

Metadane (Dublin Core) Góra-Marek, Kinga [SAP11018751] pl Gil, Barbara [SAP11016267] pl Datka, Jerzy [SAP11003748] pl 2015-09-25T12:44:28Z 2015-09-25T12:44:28Z 2009 pl
dc.identifier.issn 0926-860X pl
dc.language eng pl
dc.title Quantitative IR studies of the concentration of Co^{2+} and Co^{3+} sites in zeolites CoZSM-5 and CoFER pl
dc.type JournalArticle pl
dc.description.physical 117-122 pl
dc.abstract.en Quantitative IR experiments were realized to determine the concentration of cobalt in a form of trivalent cations being in the oxide form as well as divalent ions in exchange positions, oxide-like clusters and cobalt oxide, present in a series of cobalt-exchanged zeolites. The first step of such quantitative studies was to elaborate the experimental conditions in which probe molecules NO and CO should react selectively with either of these sites. Subsequently, the values of absorption coefficients of the 1940 cm−1 band of Co3+–NO and the 2204 cm−1 band of Co2+–CO for Co2+ in exchange positions, together with the 2194 cm−1 band of Co2+–CO for Co2+ in oxide-like clusters were determined. The linear plots of the band intensities versus the concentration of NO and CO interacting with cationic sites showed the correlation coefficients higher than 0.99. Three zeolites were investigated: CoZSM-5 (Si/Al = 15) in which most of Co2+ occupied the exchange positions, CoZSM-5 (Si/Al = 40) in which most of Co2+ was in the form of oxide-like clusters and CoO, and CoFER prepared by the contact-induced ion exchange with nearly equal amount of Co2+ in either type of the sites. The sum of the concentration of Co sites (Co3+ and Co2+) determined by IR spectroscopy was very close to the values obtained from the chemical analysis (AAS). The concentration ill-defined oxide form of Co3+ was surprisingly high as in CoZSM-5 of Si/Al = 15 it constituted about half of the overall cobalt content, and in CoFER the contribution of Co3+ reached almost 30%. pl
dc.subject.en CoZSM-5 pl
dc.subject.en CoFER pl
dc.subject.en IR spectroscopy pl
dc.subject.en absorption coefficient pl
dc.description.volume 353 pl
dc.description.number 1 pl
dc.identifier.doi 10.1016/j.apcata.2008.10.034 pl
dc.identifier.eissn 1873-3875 pl
dc.title.journal Applied Catalysis. A, General pl
dc.language.container eng pl
dc.affiliation Wydział Chemii : Zakład Chemii Nieorganicznej pl
dc.subtype Article pl

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