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http://dx.doi.org/10.18419/opus-13159
Autor(en): | Li, Zheng Rieg, Carolin Beurer, Ann-Katrin Benz, Michael Bender, Johannes Schneck, Christof Traa, Yvonne Dyballa, Michael Hunger, Michael |
Titel: | Effect of aluminum and sodium on the sorption of water and methanol in microporous MFI-type zeolites and mesoporous SBA-15 materials |
Erscheinungsdatum: | 2020 |
Dokumentart: | Zeitschriftenartikel |
Seiten: | 49-68 |
Erschienen in: | Adsorption 27 (2021), S. 49-68 |
URI: | http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-ds-131783 http://elib.uni-stuttgart.de/handle/11682/13178 http://dx.doi.org/10.18419/opus-13159 |
ISSN: | 0929-5607 1572-8757 |
Zusammenfassung: | The interaction and nature of surface sites for water and methanol sorption on MFI-type zeolites and mesoporous SBA-15 were investigated by solid-state NMR spectroscopy and correlated with the desorption enthalpies determined via TGA/DSC. For siliceous Silicalite-1, 29Si CPMAS NMR studies support stronger methanol than water interactions with SiOH groups of Q3-type. On siliceous SBA-15, SiOH groups of Q2-type are accompanied by an enhanced hydrophilicity. In aluminum-containing Na-ZSM-5, Na+ cations are strong adsorption sites for water and methanol as evidenced by 23Na MAS NMR in agreement with high desorption enthalpies of ΔH = 66-74 kJ/mol. Solid-state NMR of aluminum-containing Na-[Al]SBA-15, in contrast, has shown negligible water and methanol interactions with sodium and aluminum. Desorption enthalpies of ΔH = 44-60 kJ/mol hint at adsorption sites consisting of SiOH groups influenced by distant framework aluminum. On H-ZSM-5, Brønsted acidic OH groups are strong adsorption sites as indicated by partial protonation of water and methanol causing low-field shifts of their 1H MAS NMR signals and enhanced desorption enthalpies. Due to the small number of Brønsted acid sites in aluminum-containing H-[Al]SBA-15, water and methanol adsorption on this material is suggested to mainly occur at SiOH groups with distant framework aluminum species, as in the case of Na-[Al]SBA-15. |
Enthalten in den Sammlungen: | 03 Fakultät Chemie |
Dateien zu dieser Ressource:
Datei | Beschreibung | Größe | Format | |
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s10450-020-00275-8.pdf | 1,81 MB | Adobe PDF | Öffnen/Anzeigen |
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