The characterization of the V species and the identification of the promoting effect of dopants in V/Ti/O catalysts for o-xylene oxidation

Cavani, Fabrizio; Cortelli, Carlotta; Frattini, Alessandra; Panzacchi, Barbara; Ravaglia, V.; Trifirò, Ferruccio; Fumagalli, Carlo; Leanza, R.; Mazzoni, G.

doi:10.1016/j.cattod.2006.07.016

Cited by 28 publications

(39 citation statements)

References 28 publications

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“…Small particles (around 7 nm) with uniform size distribution were clearly seen for the 10V-Ce-Ti-O. Addition of 10% V 2 O 5 only and simultaneous addition of 10% V 2 O 5 and 5% SO 4 2-increased the particle size to about 10 nm. The mesoporosity of the V-Ce-Ti-O oxides was mainly due to the inter-particle voids.…”

Section: Catalytic Reactionsmentioning

confidence: 91%

“…Addition of 10% V 2 O 5 on the 10V-Ce-Ti-O decreased the surface areas to about 130 m 2 g -1 and increased the pore sizes to about 7 nm. Simultaneous addition of V 2 O 5 and SO 4 2-resulted in a Fig. 4.…”

Section: Catalytic Reactionsmentioning

confidence: 96%

“…The surface redox and acidic properties of the V-Ce-Ti-O could be enhanced by the addition of V 2 O 5 and SO 4 2-. These materials were tested for the selective oxidation of methanol to DMM.…”

mentioning

confidence: 97%

“…1 Introduction V 2 O 5 /TiO 2 catalysts are extensively studied in various reactions such as selective oxidation of methanol to formaldehyde [1] and methyl formate [2], selective oxidation of aromatic compounds to aromatic aldehydes [3], selective oxidation of olefins to phthalic anhydride [4], ammoxidation of aromatic hydrocarbons [5] and selective catalytic reduction of NO X [6]. It is generally true that the V 2 O 5 /TiO 2 with higher surface areas may work better since more vanadia species could be dispersed on the surface to act as active sites [7].…”

mentioning

confidence: 99%

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Preparation of Mesoporous V–Ce–Ti–O for the Selective Oxidation of Methanol to Dimethoxymethane

Liu

Sun

et al. 2008

Catal Lett

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Mesoporous V-Ce-Ti-O oxides were synthesized through the combination of sol-gel and hydrothermal methods and were characterized by different techniques. N 2 adsorption showed that the mesoporous oxides with 0-20 wt.% V 2 O 5 possessed the surface areas of about 160 m 2 g -1 with narrow pore size distribution centered around 4-5 nm. Vanadium species were highly dispersed in the samples, as confirmed by the wide angle XRD and Raman spectroscopy. The surface acidity of the materials was determined by the microcalorimetric adsorption of NH 3 . Temperature programmed reduction and O 2 chemisorption were used to probe the redox property of the materials. It was found that the mesoporous V-Ce-Ti-O possessed bifunctional characters of acidic and redox properties that catalyzed the oxidation of methanol to dimethoxymethane (DMM). These bifunctional characters were further enhanced by the addition of V 2 O 5 and SO 4 2-onto V-Ce-Ti-O simultaneously. Such supported catalysts exhibited excellent performance for the selective oxidation of methanol to DMM. Specifically, 72% conversion of methanol with 85% selectivity to DMM was achieved at 423 K over a SO 4 2--V 2 O 5 /V-Ce-Ti-O catalyst.

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Section: Catalytic Reactionsmentioning

confidence: 91%

Section: Catalytic Reactionsmentioning

confidence: 96%

mentioning

confidence: 97%

mentioning

confidence: 99%

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Preparation of Mesoporous V–Ce–Ti–O for the Selective Oxidation of Methanol to Dimethoxymethane

Liu

Sun

et al. 2008

Catal Lett

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“…Exceeding that V coverage leads to crystalline V 2 O 5 [5] regardless of preparation method, for example, classic impregnation [7], atomic layer deposition (ALD) [8], or even vapor-fed flame synthesis [9]. Crystalline V 2 O 5 has a detrimental effect on activity and selectivity [10,11]. Recently V 2 O 5 /TiO 2 catalysts prepared by flame-spray pyrolysis (FSP) showed good dispersion of vanadia while re-taining the amorphous VO x species up to a V coverage of 12 V nm −2 [12].…”

Section: Introductionmentioning

confidence: 99%

Structure of Flame‐made Vanadia/Titania and Catalytic Behaviour in the Partial Oxidation of o‐Xylene

Schimmöller

Schulz

Ritter

et al. 2008

Chemie Ingenieur Technik

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Vanadia/titania particles with a specific surface area (SSA) up to 195 m 2 g −1 and a V 2 O 5 content up to 40% (w/w) or V coverage up to 59 V nm −2 were prepared by flame spray pyrolysis (FSP) under various conditions. The catalysts were characterized by nitrogen adsorption, X-ray diffraction, temperature-programmed reduction, and in situ Raman spectroscopy and tested for partial oxidation of o-xylene. Depending on vanadia content, monomeric, polymeric, and crystalline vanadia species were formed on TiO 2 support particles by FSP. Increasing the hightemperature particle residence time and concentration (production rate) during FSP reduced the SSA and increased the vanadia coverage of TiO 2 beyond a theoretical "monolayer" (>8-10 V nm −2 ) while retaining amorphous (monomeric and polymeric) VO x surface species. Controlling liquid precursor and dispersion gas feed rates, precursor concentration, and V 2 O 5 content allowed the tailoring of SSA and the population of the different VO x species in these vanadia/titania mixed oxides. For comparison, vanadia/titania catalysts containing 10% (w/w) V 2 O 5 with comparable SSA and V coverage were prepared by impregnation, resulting in typical amorphous (<10 V nm −2 ) and crystalline (>10 V nm −2 ) VO x species. Catalysts containing 7, 10, and 20% (w/w) V 2 O 5 were deposited directly from the flame on ceramic foams that were tested for the partial oxidation of o-xylene to phthalic anhydride. The global activity of flame-made and conventionally impregnated catalysts depended mainly on SSA and vanadia loading (number of V surface sites), whereas the amorphous or crystalline nature of the VO x species seemed to be less critical. In contrast, selectivity to phthalic anhydride was significantly affected by the nature of the VO x species; amorphous species exhibited higher selectivity for conversion <90% compared with catalysts containing crystalline V 2 O 5 .

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Catalytic Properties of Polyvanadate Xerogels Supported to Anatase in Decomposition of Hydrogen Peroxide and Oxidation of o‐Xylene

Yesmurzayeva

Malibekova

Selenova

2016

Macromolecular Symposia

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Summary: The present work deals with evaluation of the catalytic properties of polyvanadate xerogels deposited on titanium dioxide (anatase). Xerogels of polyvanadates in the form of nanofibers were obtained by sol-gel method. The average sizes of polyvanadate nanoparticles in aqueous solution determined by DLS were equal to 7 and 50 nm. TEM results reveal the formation of nanostructured thin layers of polyvanadates on the surface of TiO 2 particles. The catalytic properties of polyvanadates deposited on the surface of anatase by impregnation method were studied with respect to decomposition of hydrogen peroxide and oxidation of o-xylene under mild conditions.

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The characterization of the V species and the identification of the promoting effect of dopants in V/Ti/O catalysts for o-xylene oxidation

Cited by 28 publications

References 28 publications

Preparation of Mesoporous V–Ce–Ti–O for the Selective Oxidation of Methanol to Dimethoxymethane

Preparation of Mesoporous V–Ce–Ti–O for the Selective Oxidation of Methanol to Dimethoxymethane

Structure of Flame‐made Vanadia/Titania and Catalytic Behaviour in the Partial Oxidation of o‐Xylene

Catalytic Properties of Polyvanadate Xerogels Supported to Anatase in Decomposition of Hydrogen Peroxide and Oxidation of o‐Xylene

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