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Titolo:
Incorporation of transition metal ions in aluminophosphate molecular sieves with AST structure
Autore:
Frunza, L; Pelgrims, J; Leeman, H; Van Der Voort, P; Vansant, EF; Schoonheydt, RA; Weckhuysen, BM;
Indirizzi:
Katholieke Univ Leuven, Dept Interfasechem, Ctr Oppervlaktechem Katalyse, B-3001 Heverlee, Belgium Katholieke Univ Leuven Heverlee Belgium B-3001 B-3001 Heverlee, Belgium Univ Instelling Antwerp, Lab Anorgan Scheikunde, Dept Scheikunde, B-2610 Wilrijk, Belgium Univ Instelling Antwerp Wilrijk Belgium B-2610 , B-2610 Wilrijk, Belgium Univ Utrecht, Debye Inst, Dept Anogan Chem Katalyse, NL-3508 TB Utrecht, Netherlands Univ Utrecht Utrecht Netherlands NL-3508 TB 3508 TB Utrecht, Netherlands
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 14, volume: 105, anno: 2001,
pagine: 2677 - 2686
SICI:
1520-6106(20010412)105:14<2677:IOTMII>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
ELECTRON-SPIN-ECHO; ADSORBATE INTERACTIONS; FRAMEWORK SUBSTITUTION; CATALYTIC PROPERTIES; RIETVELD REFINEMENT; EXPERIMENTAL-DESIGN; THERMAL-STABILITY; RESONANCE; CHROMIUM; MODULATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
64
Recensione:
Indirizzi per estratti:
Indirizzo: Weckhuysen, BM Katholieke Univ Leuven, Dept Interfasechem, Ctr Oppervlaktechem Katalyse, Kardinaal Mercierlaan 92, B-3001 Heverlee, Belgium Katholieke Univ Leuven Kardinaal Mercierlaan 92 Heverlee Belgium B-3001
Citazione:
L. Frunza et al., "Incorporation of transition metal ions in aluminophosphate molecular sieves with AST structure", J PHYS CH B, 105(14), 2001, pp. 2677-2686

Abstract

Transition metal ion containing aluminophosphate molecular sieves with AlPO4-16 (AST) structure have been synthesized using the classic template, quinuclidine, and the corresponding salts of V4+, Co2+, Cr3+, and Mn2+. The cubic AST form was the main product. but in the presence of fluoride ions, the tetragonal AST form could also be obtained. The AST materials were characterized with X-ray diffraction, thermal analysis, scanning electron microscopy, electron spin resonance, infrared spectroscopy, and diffuse reflectance spectroscopy in the UV-vis-NIR region. Spectroscopic measurements showed that small amounts of Co2+ and Mn2+ can be incorporated in the framework. The diffuse reflectance spectra are indicative for the presence of two typesof Co2+, most probably taking the two framework positions T-1 and T-2 witha T-1:T-2 occupation ratio of 3-8. In contrast, V4+ is present in defect sites by coordination to two (or three) framework oxygen atoms, The incorporation of Cr3+ in the AST framework is also uncertain and two surface Cr3+ species were observed: clusters similar to the bulk Cr2O3 oxide and isolatedCr3+ ions in strongly distorted octahedral coordination. These spectroscopic observations were confirmed by thermal analysis results, which showed that the degree of metal ion incorporation is inversely proportional with thephase transition temperature of AST to berlinite. Furthermore, Co2+ and V4 are very stable in the AST structure and difficult to oxidize upon heating.

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Documento generato il 14/08/20 alle ore 16:35:57