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Titolo:
Paramagnetic cupric ions ion-exchanged into TAPO-5 and TAPO-11 molecular sieves
Autore:
Kim, BY; Yu, JS; Lee, CW;
Indirizzi:
Hannam Univ, Dept Chem, Taejon, South Korea Hannam Univ Taejon South Korea nam Univ, Dept Chem, Taejon, South Korea Korea Res Inst Chem Technol, Solid State Chem lab, Taejon 305606, South Korea Korea Res Inst Chem Technol Taejon South Korea 305606 05606, South Korea
Titolo Testata:
BULLETIN OF THE KOREAN CHEMICAL SOCIETY
fascicolo: 2, volume: 21, anno: 2000,
pagine: 251 - 258
SICI:
0253-2964(20000220)21:2<251:PCIIIT>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
ELECTRON-SPIN-RESONANCE; ECHO MODULATION SPECTROSCOPIES; ADSORBATE INTERACTIONS; CATALYTIC PROPERTIES; TITANIUM SILICALITE; OXIDE SURFACES; ZEOLITES; LOCATION; GALLOSILICATE; OXIDATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
45
Recensione:
Indirizzi per estratti:
Indirizzo: Yu, JS Hannam Univ, Dept Chem, 133 Ojung Dong, Taejon, South Korea Hannam Univ 133 Ojung Dong Taejon South Korea Taejon, South Korea
Citazione:
B.Y. Kim et al., "Paramagnetic cupric ions ion-exchanged into TAPO-5 and TAPO-11 molecular sieves", B KOR CHEM, 21(2), 2000, pp. 251-258

Abstract

Titaniumaluminophosphate molecular sieves TAPO-5 and TAPO-11 have been hydrothermally synthesized. These materials were characterized using XRD, TGA,BET, ICP, diffuse reflectance UV-Vis and IR techniques. Especially, infrared and diffuse reflectance UV-Vis spectroscopic measurements were made in order to determine the evidence for framework substitution of Ti into AlPO4 materials. The calcined TAPO-5 and TAPO-11 molecular sieves were ion-exchanged with cupric nitrate solution. The location and interactions of cupric ions ion-exchanged into H-TAPO-5 and H-TAPO-11 molecular sieves with water and ammonia have been studied by electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies. Similarity and difference in Cu(II) location and coordination were discussed in these two structures. There is a gradual transition upon dehydration of Cu-TAPO-5 from a Cu(II) species with ESR parameters g(parallel to) = 2.401, A(parallel to) = 155 x 10(-4) cm(-1), and g(perpendicular to) = 2.08 to a CuO species with g(parallel to) = 2.348, A(parallel to) = 167 x 10(-4) cm(-1) and g(perpendicular to) = 2.07. A similar gradual transition upon dehydration of Cu-TAPO-11 was also observed from a Cu(II) species with ESR parameters g(parallel to) = 2.375, A(parallel to) = 151 x 10(-4) cm(-1) and g(perpendicular to) = 2.08 to a Cu(II) species with g(parallel to) = 2.333, A(parallel to) = 170 x 10(-4) cm(-1) and = 2.07. In the hydrated state, Cu(II) ion directly coordinates to three water molecules in Cu-TAPO-5 cm while to two water molecules in Cu-TAPO-11. Upon dehydration treatments, Cu(II) is suggested to be located in hexagonal prism sites recessed from a main channel for both Cu-TAPO-5 and Cu-TAPO-11. Upon equilibration with ammonia, Cu(II) forms a complex containing four molecules of ammonia for both structures based on resolved nitrogen hyperfine interaction.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/09/20 alle ore 04:36:01