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IR studies of OH groups in mesoporous aluminosilicates

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IR studies of OH groups in mesoporous aluminosilicates

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dc.contributor.author Góra-Marek, Kinga [SAP11018751] pl
dc.contributor.author Datka, Jerzy [SAP11003748] pl
dc.date.accessioned 2015-09-24T09:08:01Z
dc.date.available 2015-09-24T09:08:01Z
dc.date.issued 2006 pl
dc.identifier.issn 0926-860X pl
dc.identifier.uri http://ruj.uj.edu.pl/xmlui/handle/item/15783
dc.language eng pl
dc.title IR studies of OH groups in mesoporous aluminosilicates pl
dc.type JournalArticle pl
dc.description.physical 104-109 pl
dc.abstract.en The properties of acidic hydroxyl groups and Lewis acid sites in amorphous mesoporous aluminosilicates was followed by quantitative IR studies of ammonia adsorption and by low temperature studies of CO adsorption. We studied aluminosilicates synthesized by three methods: via atrane complexes, by grafting aluminium onto the siliceous material (HMCM-48) and in aqueous solution following a typical synthesis procedure (HMCM-41). IR spectra of OH groups showed weak but well seen band of Si–(OH)–Al groups at 3600–3610 cm−1. The post-synthesis grafting of Al into MCM-48 was found to be the most effective way to produce mesoporous material with large content of Brønsted acid sites. IR studies have shown that the stoichiometry of dehydroxylation of the amorphous mesoporous materials was different than for zeolites: in mesoporous materials one Brønsted site lost created one Lewis acid site. IR experiments of CO sorption evidenced that generally two kinds of Si–(OH)–Al groups exist in mesoporous aluminosilicates: weakly acidic ones of ΔνOH⋯CO ≈ 160 cm−1 (similar to that in zeolite NaHX), present in all the materials, hydroxyls of moderate acidity of ΔνOH⋯CO ≈ 200 cm−1 (acid strength intermediate between that in zeolites NaHX and NaHY) present in HMCM-41 and HMCM-48, or hydroxyls of high acidity of ΔνOH⋯CO ≈ 300 cm−1 (similar to that in highly siliceous zeolite HZSM-5) present in aluminoslicate prepared via atrane complexes method. This method of synthesis was found to be the most effective in preparation of mesoporous aluminosilicates with the strongest Brønsted acid sites. The weakly acidic hydroxyls in mesoporous aluminosilicates are very prone to dehydroxylation, they are lost at as low temperature as 800 K, hydroxyls of moderate, or high acidity are resistant to dehydroxylation and behave like zeolitic OH groups. pl
dc.subject.en acidity pl
dc.subject.en OH groups pl
dc.subject.en mesoporous materials pl
dc.subject.en dehydroxylation pl
dc.subject.en IR spectroscopy pl
dc.description.volume 302 pl
dc.description.number 1 pl
dc.identifier.doi 10.1016/j.apcata.2005.12.027 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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