Publikace detail

Determination of Zn Speciation, Siting, and Distribution in Ferrierite Using Luminescence and FTIR Spectroscopy

Rok: 2021

Druh publikace: článek v odborném periodiku

Název zdroje: Journal of Physical Chemistry C

Název nakladatele: American Chemical Society

Místo vydání: Washington

Strana od-do: 9060-9073

Tituly:

Jazyk	Název	Abstrakt	Klíčová slova
cze	Stanovení Zn druhů, prostorového uspořádání a distribuce ve ferrieritu pomocí luminiscenční a FTIR spektroskopie	Metodologie pro analýzu poloh Zn2+ iontů v extra-mřížkových kationtových polohách Si-bohatých zeolitů byla vyvinuta a demonstrována na Zn-ferrieritových vzorcích (Si/Al 8.5, Zn/Al 0.04-0.33). Metodologie je založena na FTIR a luminiscenční spektroskopii.	luminiscenční spektroskopie; FTIR; zeolity; kationtové polohy; Zn druhy
eng	Determination of Zn Speciation, Siting, and Distribution in Ferrierite Using Luminescence and FTIR Spectroscopy	A methodology for the analysis of the siting of Zn2+ ions in extra-framework cationic sites of silicon-rich zeolite was developed and demonstrated on Zn-ferrierite samples (Si/Al 8.5, Zn/Al 0.04-0.33). This methodology is based on the FTIR spectroscopy of antisymmetric tetrahedral-octahedral-tetrahedral (T-O-T) vibrations of the zeolite framework perturbed by Zn2+ ions, combined with a complementary approach based on Zn2+ luminescence monitored by laser-induced time-resolved luminescence spectroscopy. Three vibration bands in the FTIR spectra of antisymmetric T-O-T vibrations of dehydrated zeolite reflect Zn2+ ligation in three extra-framework cationic sites of ferrierite zeolite. The band at 935 cm(-1) corresponds to Zn2+ ions in the alpha-site of ferrierite, the band at 917 cm(-1) correspondsto ions in beta-site, and the band at 902 cm(-1) correspondsto Zn2+ ions in the.-site. The extinction coefficient for quantitative analysis of Zn2+ ions in cationic sites was estimated and exhibited the same value for Zn2+ cations in all cationic sites, epsilon = 49.1 +/- 3.8 cm.mu mol(-1). In all Zn samples, Zn2+ siting in the beta-site prevails, while Zn2+ ions in the gamma-site are of low population or negligible. Time-resolved luminescence showed that bare Zn2+ ions in the extra-framework cationic sites can be distinguished from Zn2+ ions in ZnO by a decay time which is several magnitudes longer and a high sensitivity for quenching. The luminescence spectrum of Zn-ferrierites is composed of three bands at 545, 480, and 425 nm attributable to Zn2+ ions in the alpha-, beta-, and gamma-site with luminescence coefficients (for semiquantitative analysis) zeta(alpha) = 10.1, zeta(beta) = 9.4, and zeta(gamma) = 8.8 mmol/g of Zn2+ ions in the alpha-, beta-, and gamma-sites, respectively. The analysis of Zn ions in ferrierites showed that ZnH-ferrierites exclusively contain Zn2+ ions in cationic sites. In the case of the ZnNa-FER sample with maximum Zn loading (Zn/Al 0.33), a small	laser-induced luminescence; modified zsm-5 zeolites; ion-exchanged cations; o-t vibrations; cu+ ions; co ions; dissociative adsorption; chemical activation; catalytic cracking; n2o decomposition

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