TNU-9 Zeolite: Aluminum Distribution and Extra-Framework Sites of Divalent Cations

0476026 - ÚFCH JH 2018 RIV DE eng J - Journal Article
Karcz, R. - Dědeček, Jiří - Supronowicz, B. - Thomas, Haunani M. - Klein, Petr - Tabor, Edyta - Sazama, Petr - Pashkova, Veronika - Sklenák, Štěpán
TNU-9 Zeolite: Aluminum Distribution and Extra-Framework Sites of Divalent Cations.
Chemistry - A European Journal. Roč. 23, JUL 2017 (2017), s. 8857-8870. ISSN 0947-6539. E-ISSN 1521-3765
R&D Projects: GA ČR(CZ) GA15-14007S; GA MŠMT(CZ) LM2015073
Grant - others:Ga MŠk(CZ) LM2015070
Institutional support: RVO:61388955
Keywords : Aluminum * Cobalt * Density functional calculations * Structure elucidation * Zeolites
OECD category: Physical chemistry
Impact factor: 5.160, year: 2017

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 of 29Si and 27Al (3Q) MAS NMR spectroscopy, CoII as 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 a and beta (15 and 85%, respectively, of aluminum pairs) sites of bare divalent cations. The a site is located on the TUN straight channel wall and it connects two channel intersections. The suggested near- planar b site is present at the channel intersection.
Permanent Link: http://hdl.handle.net/11104/0272594