title: TNU-9 Zeolite: Aluminum Distribution and Extra-Framework Sites of Divalent Cations.
abstract: The TNU-9 zeolite (TUN framework) is one of the most complex zeolites known. It represents a highly promising matrix for both acid and redox catalytic reactions. We present here a newly developed approach involving the use of29Si and27Al (3Q) MAS NMR spectroscopy, CoIIas probes monitored by UV/Vis and FTIR spectroscopy, and extensive periodic DFT calculations, including molecular dynamics, to investigating the aluminum distribution in the TUN framework and the location of aluminum pairs and divalent cations in extra-framework cationic positions. Our study reveals that 40 and 60 % of aluminum atoms in the TNU-9 zeolite are isolated single aluminum atoms and aluminum pairs, respectively. The aluminum pairs are present in two types of six-membered rings forming the corresponding α and β (15 and 85 %, respectively, of aluminum pairs) sites of bare divalent cations. The α site is located on the TUN straight channel wall and it connects two channel intersections. The suggested near-planar β site is present at the channel intersection.
authors.affiliation: J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejskova 3, Prague 8, 182 23, Czech Republic.|J. Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, Cracow, 30-239, Poland.
authors.forename: Robert
authors.initials: R
authors.lastname: Karcz
authors.affiliation: J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejskova 3, Prague 8, 182 23, Czech Republic.
authors.forename: Jiri
authors.initials: J
authors.lastname: Dedecek
authors.affiliation: J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejskova 3, Prague 8, 182 23, Czech Republic.
authors.forename: Barbara
authors.initials: B
authors.lastname: Supronowicz
authors.affiliation: J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejskova 3, Prague 8, 182 23, Czech Republic.
authors.forename: Haunani M
authors.initials: HM
authors.lastname: Thomas
authors.affiliation: J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejskova 3, Prague 8, 182 23, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Klein
authors.affiliation: J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejskova 3, Prague 8, 182 23, Czech Republic.
authors.forename: Edyta
authors.initials: E
authors.lastname: Tabor
authors.affiliation: J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejskova 3, Prague 8, 182 23, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Sazama
authors.affiliation: J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejskova 3, Prague 8, 182 23, Czech Republic.
authors.forename: Veronika
authors.initials: V
authors.lastname: Pashkova
authors.affiliation: J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejskova 3, Prague 8, 182 23, Czech Republic.
authors.forename: Stepan
authors.identifier: http://orcid.org/0000-0003-4862-857X
authors.initials: S
authors.lastname: Sklenak
keywords: aluminum; cobalt; density functional calculations; structure elucidation; zeolites