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Titolo:
UV resonance Raman spectroscopic studies on the genesis of highly dispersed surface molybdate species on gamma-alumina
Autore:
Xiong, G; Feng, ZC; Li, J; Yang, QH; Ying, PL; Xin, Q; Li, C;
Indirizzi:
Chinese Acad Sci, Dalian Inst Chem Phys, State Key Lab Catalysis, Dalian 116023, Peoples R China Chinese Acad Sci Dalian Peoples R China 116023 n 116023, Peoples R China
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 15, volume: 104, anno: 2000,
pagine: 3581 - 3588
SICI:
1520-6106(20000420)104:15<3581:URRSSO>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
SUPPORTED MOLYBDENUM OXIDE; PARTIAL OXIDATION; PHYSICOCHEMICAL CHARACTERIZATION; HYDRODESULFURIZATION CATALYSTS; INFRARED-SPECTROSCOPY; MOO3/SIO2 CATALYSTS; SILICON DIOXIDE; COKE FORMATION; SPECTRA; REFLECTANCE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
59
Recensione:
Indirizzi per estratti:
Indirizzo: Li, C Chinese Acad Sci, Dalian Inst Chem Phys, State Key Lab Catalysis, POB 110,Dalian 116023, Peoples R China Chinese Acad Sci POB 110 Dalian Peoples R China 116023 ples R China
Citazione:
G. Xiong et al., "UV resonance Raman spectroscopic studies on the genesis of highly dispersed surface molybdate species on gamma-alumina", J PHYS CH B, 104(15), 2000, pp. 3581-3588

Abstract

The surface molybdate species and their coordination structures on gamma-alumina are characterized by UV resonance Raman spectroscopy and UV-vis diffuse reflectance spectroscopy. The surface tetrahedral and octahedral molybdate species can be definitely identified on the basis of the resonance Raman effect. The evolution of surface species has been studied during the catalyst preparation under various conditions including the pH value of the impregnating solution and the pretreatment temperature. It is shown that the coordination structures of the supported molybdate in the wet state are dependent on the structures of molybdate in the impregnation solution as well as the surface property of gamma-alumina. When the impregnating solution is at pH = 10.0, only tetrahedral molybdate species are formed on gamma-alumina, while both tetrahedral and octahedral species are formed on gamma-alumina at pH = 3.0, although the molybdate is in only the octahedral form in theimpregnation solution at pH = 3.0. For the samples prepared by the impregnating solution of (NH4)(6)Mo7O24, some surface tetrahedral molybdate species polymerize to the octahedral species during calcination even when the loading of molybdate is extremely low. However, the surface molybdate species hardly aggregate into the octahedral species when the sample prepared by the impregnating solution of Na2MoO4. It turns out that the "surface pH value" (i.e., the pH value of surface region) is a key factor governing the coordination structure of the surface molybdate species.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/11/20 alle ore 16:35:21