Spying on Fe ions and their role in modified aluminosilicates during the sorption of anions using solid-state NMR spectroscopy

0469645 - ÚMCH 2017 RIV NL eng J - Článek v odborném periodiku
Kobera, Libor - Abbrent, Sabina - Holcova, L. - Urbanová, Martina - Koloušek, D. - Doušová, B. - Brus, Jiří
Spying on Fe ions and their role in modified aluminosilicates during the sorption of anions using solid-state NMR spectroscopy.
Microporous and Mesoporous Materials. Roč. 241, 15 March (2017), s. 115-122. ISSN 1387-1811. E-ISSN 1873-3093
Grant CEP: GA ČR(CZ) GA13-24155S; GA ČR(CZ) GA16-13778S
Institucionální podpora: RVO:61389013
Klíčová slova: paramagnetic NMR shift * solid-state NMR * aluminosilicate
Obor OECD: Civil engineering
Impakt faktor: 3.649, rok: 2017

Post-synthetic modifications of zeolites enable their possible use as adsorbents in separation and purification processes. Here, we present a multinuclear (29Si, 27Al, 31P) magnetic resonance study of solid samples of zeolite A (LTA) and hydroxysodalite (HS), their post-synthetic modification using FeSO4 solution, and the results of their analysis by NMR after the anion (PO43-) adsorption process. High-resolution 29Si and 27Al MAS NMR spectra provide valuable structural information on the oxidation of Fe2+ ions to Fe3+ species during the modification process, whereas 27Al 3Q/MAS solid-state NMR spectra of LTA and HS unveil a simultaneous dealumination process characteristic of acid leaching in aluminosilicate systems. 31P solid-state NMR spectra of LTA and HS, collected at “very-fast” spinning speed, revealed a dramatic change in the chemical shift values for the phosphates present, directly characteristic of FePO4 in the case of LTA, and phosphates of alkali and/or alkaline earth metals in the case of HS. Moreover, density functional theoretical (DFT) computations provide satisfactory agreement with the obtained 27Al and 29Si experimental data. This work demonstrates possible NMR approaches to the characterization of complex framework materials and provides key insights into aluminosilicate materials affected by unpaired electron(s).
Trvalý link: http://hdl.handle.net/11104/0269275