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 $\Delta$Hþinspace=þinspace66--74 kJ/mol. Solid-state NMR of aluminum-containing Na-AlSBA-15, in contrast, has shown negligible water and methanol interactions with sodium and aluminum. Desorption enthalpies of $\Delta$Hþinspace=þinspace44--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-AlSBA-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-AlSBA-15.
%0 Journal Article
%1 Li2020
%A Li, Zheng
%A Rieg, Carolin
%A Beurer, Ann-Katrin
%A Benz, Michael
%A Bender, Johannes
%A Schneck, Christof
%A Traa, Yvonne
%A Dyballa, Michael
%A Hunger, Michael
%D 2020
%J Adsorption
%K bender icvt journal
%R 10.1007/s10450-020-00275-8
%T Effect of aluminum and sodium on the sorption of water and methanol in microporous MFI-type zeolites and mesoporous SBA-15 materials
%U https://doi.org/10.1007/s10450-020-00275-8
%X 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 $\Delta$Hþinspace=þinspace66--74 kJ/mol. Solid-state NMR of aluminum-containing Na-AlSBA-15, in contrast, has shown negligible water and methanol interactions with sodium and aluminum. Desorption enthalpies of $\Delta$Hþinspace=þinspace44--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-AlSBA-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-AlSBA-15.
@article{Li2020,
abstract = {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 $\Delta$H{\thinspace}={\thinspace}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 $\Delta$H{\thinspace}={\thinspace}44--60 kJ/mol hint at adsorption sites consisting of SiOH groups influenced by distant framework aluminum. On H-ZSM-5, Br{\o}nsted 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 Br{\o}nsted 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.},
added-at = {2021-06-07T11:14:48.000+0200},
author = {Li, Zheng and Rieg, Carolin and Beurer, Ann-Katrin and Benz, Michael and Bender, Johannes and Schneck, Christof and Traa, Yvonne and Dyballa, Michael and Hunger, Michael},
biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2b879d9c0f07fb1ceb18c083d73fea2e2/danieldobesch},
doi = {10.1007/s10450-020-00275-8},
interhash = {37d6cae9bee966fe1d4158d6625d4749},
intrahash = {b879d9c0f07fb1ceb18c083d73fea2e2},
issn = {1572-8757},
journal = {Adsorption},
keywords = {bender icvt journal},
timestamp = {2021-06-07T09:23:03.000+0200},
title = {Effect of aluminum and sodium on the sorption of water and methanol in microporous MFI-type zeolites and mesoporous SBA-15 materials},
url = {https://doi.org/10.1007/s10450-020-00275-8},
year = 2020
}
