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Titolo:
Surface alteration of (VO)(2)P2O7 by alpha-Sb2O4 as a route to control then-butane selective oxidation
Autore:
Ait-Lachgar-Ben Abdelouabad, K; Roullet, M; Brun, M; Burrows, A; Kiely, CJ; Volta, JC; Abon, M;
Indirizzi:
Inst Rech Catalyse, CNRS, F-69626 Villeurbanne, France Inst Rech CatalyseVilleurbanne France F-69626 9626 Villeurbanne, France Univ Liverpool, Dept Mat Sci & Engn, Liverpool L69 3GH, Merseyside, England Univ Liverpool Liverpool Merseyside England L69 3GH , Merseyside, England
Titolo Testata:
APPLIED CATALYSIS A-GENERAL
fascicolo: 1-2, volume: 210, anno: 2001,
pagine: 121 - 136
SICI:
0926-860X(20010309)210:1-2<121:SAO(BA>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
P-O CATALYSTS; VANADYL PYROPHOSPHATE; MALEIC-ANHYDRIDE; PHASE COOPERATION; ACTIVATION METHOD; OXIDE CATALYSTS; ION-SCATTERING; VPO CATALYSTS; ACIDITY; MECHANOCHEMISTRY;
Keywords:
n-butane selective oxidation; synergetic effects; (VO)(2)P2O7/alpha-Sb2O4 mechanical mixtures; ODH versus partial oxidation;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Engineering, Computing & Technology
Citazioni:
42
Recensione:
Indirizzi per estratti:
Indirizzo: Volta, JC Inst Rech Catalyse, CNRS, 2 Ave Albert Einstein, F-69626 Villeurbanne, France Inst Rech Catalyse 2 Ave Albert Einstein Villeurbanne FranceF-69626
Citazione:
K. Ait-Lachgar-Ben Abdelouabad et al., "Surface alteration of (VO)(2)P2O7 by alpha-Sb2O4 as a route to control then-butane selective oxidation", APP CATAL A, 210(1-2), 2001, pp. 121-136

Abstract

The catalytic properties of (VO)(2)P2O7/alpha -Sb2O4 mixed oxides system for n-butane mild oxidation have been investigated on two mechanical mixtures (M1 and M2) of the same well crystallized (VO)(2)P2O7 (reference vanadyl pyrophosphate) with two different morphologies of alpha -Sb2O4. The M1 mixture of (VO)(2)P2O7 with alpha -Sb2O4 (1), prepared by oxidationof Sb2O3, leads to the oxidative dehydrogenation (ODH) of n-butane, whereas the M2 mixture of (VO)(2)P2O7 With a commercial alpha -Sb2O4 (2) (Aldrich) with a different morphology improves the maleic anhydride selectivity as compared to the reference (VO)zP207 catalyst (synergetic effect). After reaction, no ternary VPSbO phase is detected by XRD and DTA and it was controlled that the two alpha -Sb2O4 oxides are catalytically inactive. The (VO)(2)P2O7 reference catalyst which produced only maleic anhydride asmild oxidation product shows by XPS a slightly oxidized surface (14% V5+-86% V4+). Contamination of the (VO)(2)P2O7 phase by migration of Sb species occurs after catalytic reaction in the case of the M1 mixture as shown by XPS, LEISand TEM-EDX analysis. XPS showed that (VO)(2)P2O7 is partially superficially reduced (86% V4+-14% V3+). This feature is consistent with the decrease of acidity as observed by pyridine adsorption-desorption. In opposition with the M1 mixture, no contamination of the (VO)(2)P2O7 phase is observed after catalytic reaction in the case of the M2 mixture. The XPS study shows, in this case, that (VO)(2)P2O7 is partially oxidized (30% V5+-70% V4+) at a higher level than for the reference (VO)(2)P2O7 catalyst. This situation is associated with the increase of selectivity observed formaleic anhydride (synergetic effect). The difference in the catalytic results for the two M1 and M2 mixtures, ascompared to the (VO)(2)P2O7 reference catalyst, can be explained by the alteration of the surface composition of (VO)(2)P2O7 and the distribution of vanadium oxidation state due to different interaction between Sb2O4 and (VO)(2)P2O7, depending on the orientation of the alpha -Sb2O4, crystals. (C) 2001 Elsevier Science B.V, All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 15/07/20 alle ore 04:56:43