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Vanadium oxides supported on TiO2-Sepiolite and Sepiolite: Preparation, structural and acid characterization and catalytic behaviour in selective oxidation of toluene

Paper ID Volume ID Publish Year Pages File Format Full-Text
43668 45981 2007 9 PDF Available
Title
Vanadium oxides supported on TiO2-Sepiolite and Sepiolite: Preparation, structural and acid characterization and catalytic behaviour in selective oxidation of toluene
Abstract

The synthesis of vanadium oxide systems (5–20 wt% of V2O5) supported on TiO2-Sepiolite (with titania loading around the theoretical monolayer, 12 wt%) and on Sepiolite was carried out by the wet impregnation method. Materials were characterized by EDX, XRD, DR UV–vis, Raman, 29Si and 1H MAS NMR, TEM and nitrogen adsorption. Surface acid properties were evaluated through pyridine chemisorption. Their catalytic behaviour in the selective oxidation of toluene was studied. All solids exhibited the type IV isotherm, which corresponds to mesoporous solids. The decomposition of the Sepiolite into magnesium silicate and silica due to the effects of the vanadium incorporation process and calcination was not observed. The nature of the vanadium species depended on the support type and vanadium loading. Thus, in general, at the lowest vanadia loadings, isolated tetrahedral and polymetavanadate type species predominated. At higher loadings (15 wt% or above), vanadium oxides were also presented as crystalline V2O5 nanoparticles and, especially in %V/Sepc systems, as pyro- and meta-magnesium vanadates. On the other hand, in relation to the supports, the vanadium systems exhibited new acid sites whose density and strength both depended on the vanadia species structures. The catalytic performance of the vanadium oxide systems in the selective oxidation of toluene was also influenced by the structure and nature of vanadia species. Thus, the species formed on TiO2-coated Sepiolite support exhibited more activity in the formation of benzaldehyde (and benzoic acid) than the ones on Sepiolite. This formation is favoured by the polymeric vanadia species.

Keywords
TiOx-Sepiolite supported vanadium oxide; Sepiolite supported vanadium oxide; TiOx-Sepiolite; Sepiolite; Catalyst characterization (EDX/XRD/DR-UV–vis/Raman/1H,29Si MAS NMR/TEM) pyridine chemisorption; Toluene selective oxidation
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Vanadium oxides supported on TiO2-Sepiolite and Sepiolite: Preparation, structural and acid characterization and catalytic behaviour in selective oxidation of toluene
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 325, Issue 2, 15 June 2007, Pages 336–344
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us