Oxygen chemisorption on titania-zirconia mixed oxide supported vanadium oxide catalysts

Reddy, Benjaram M.; Manohar, B.; Reddy, E. Padmanabha

doi:10.1021/la00031a028

Cited by 48 publications

(28 citation statements)

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“…2, is due to the overlapping contribution of oxygen from titania and zirconia in the case of TiO 2 -ZrO 2 support, and to titania, zirconia, and vanadia in the case of the 12% V 2 O 5 /TiO 2 -ZrO 2 catalyst, respectively. Figure 3 shows the binding energies of Ti 2p photoelectron peaks at 458.5 and 464.4 eV for Ti 2p 3/2 and Ti 2p 1/2 lines, respectively, which agree well with the values reported in the literature [16,29,30]. Interestingly, the intensity of the Ti 2p core level spectra increases with increasing calcination temperature.…”

Section: Resultssupporting

confidence: 87%

Monolayer V2O5/TiO2–ZrO2 catalysts for selective oxidation of o-xylene: preparation and characterization

et al. 2011

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A series of TiO 2 -ZrO 2 supported V 2 O 5 catalysts with vanadia loadings ranging from 4 to 12 wt% were synthesized by a wet impregnation technique and subjected to various thermal treatments at temperatures ranging from 773 to 1,073 K to understand the dispersion and thermal stability of the catalysts. The prepared catalysts were characterized by X-ray powder diffraction (XRD), BET surface area, oxygen uptake, and X-ray photoelectron spectroscopy (XPS) techniques. XRD results of 773 K calcined samples conferred an amorphous nature of the mixed oxide support and a highly dispersed form of vanadium oxide. Oxygen uptake measurements supported the formation of a monolayer of vanadium oxide over the thermally stable TiO 2 -ZrO 2 support. The O 1s, Ti 2p, Zr 3d, and V 2p core level photoelectron peaks of TiO 2 -ZrO 2 and V 2 O 5 /TiO 2 -ZrO 2 catalysts are sensitive to the calcination temperature. No significant changes in the oxidation states of Ti 4? and Zr 4? were noted with increasing thermal treatments. Vanadium oxide stabilized as V 4? at lower temperatures, and the presence of V 5? is observed at 1,073 K. The synthesized catalysts were evaluated for selective oxidation of o-xylene under normal atmospheric pressure in the temperature range of 600-708 K. The TiO 2 -ZrO 2 support exhibits very less conversion of o-xylene, while 12 wt% V 2 O 5 loaded sample exhibited a good conversion and a high product selectivity towards the desired product, phthalic anhydride.

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Section: Resultssupporting

confidence: 87%

Monolayer V2O5/TiO2–ZrO2 catalysts for selective oxidation of o-xylene: preparation and characterization

et al. 2011

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“…This conclusion is further supported from FTIR and ESCA measurements. The O 2 uptake results published earlier also revealed that vanadium oxide is in a highly dispersed state on the support surface up to the monolayer capacity. The TiO 2 −ZrO 2 mixed oxide support had a BET surface area of 160 m 2 g -1 .…”

Section: Resultsmentioning

confidence: 54%

Characterization of V₂O₅/TiO₂−ZrO₂ Catalysts by XPS and Other Techniques

Reddy¹,

Chowdhury²,

Ganesh³

et al. 1998

J. Phys. Chem. B

101

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A high surface area titania-zirconia mixed oxide support was prepared by the technique of precipitation from homogeneous solutions. Vanadia (12 wt %) was impregnated on TiO 2 -ZrO 2 support by using an oxalic acid solution of NH 4 VO 3 . The TiO 2 -ZrO 2 binary oxide support and the V 2 O 5 /TiO 2 -ZrO 2 catalyst were then subjected to thermal treatments from 500 to 800 °C. The influence of thermal treatments on the dispersion and stability of the catalyst was investigated by X-ray diffraction (XRD), FT infrared (FTIR), UV-vis absorption, and X-ray photoelectron spectroscopy (XPS) techniques. The characterization results suggest that the TiO 2 -ZrO 2 binary oxide support is thermally quite stable up to 800 °C. Calcination of the coprecipitated titanium-zirconium hydroxides at 500 °C result in the formation of an amorphous phase, and further heating at 600 °C converts this amorphous phase into a crystalline ZrTiO 4 compound. Impregnation of V 2 O 5 and heating of the V 2 O 5 /TiO 2 -ZrO 2 catalyst beyond 600 °C results in the formation of ZrV 2 O 7 , with the simultaneous presence of the TiO 2 rutile phase. However, the vanadia is in a highly dispersed state on the TiO 2 -ZrO 2 mixed oxide support when calcined at less than 600 °C.

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“…The FT-IR spectra of the sample also supported the XRD observations. The O 2 chemisorption measurements obtained as per the procedure described elsewhere [31] also revealed that the MoO 3 is in a highly-dispersed state on the support surface at 773 K calcination temperature. Chemisorption of O 2 is possible only on the reduced Mo oxide, which contains coordinately-unsaturated sites.…”

Section: Resultsmentioning

confidence: 80%

“…The FT-IR spectra were recorded on a Nicolet 740 FT-IR spectrometer at ambient conditions using KBr discs with a nominal resolution of 4 cm −1 and averaging 1 0 0 spectra. Oxygen chemisorption measurements were made as per the procedure described elsewhere [31].…”

Section: Catalyst Characterizationmentioning

confidence: 99%

An XPS study of dispersion and chemical state of MoO3 on Al2O3-TiO2 binary oxide support

Reddy

Chowdhury

Reddy

et al. 2001

Applied Catalysis A: General

104

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Oxygen chemisorption on titania-zirconia mixed oxide supported vanadium oxide catalysts

Cited by 48 publications

References 1 publication

Monolayer V2O5/TiO2–ZrO2 catalysts for selective oxidation of o-xylene: preparation and characterization

Monolayer V2O5/TiO2–ZrO2 catalysts for selective oxidation of o-xylene: preparation and characterization

Characterization of V₂O₅/TiO₂−ZrO₂ Catalysts by XPS and Other Techniques

An XPS study of dispersion and chemical state of MoO3 on Al2O3-TiO2 binary oxide support

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Oxygen chemisorption on titania-zirconia mixed oxide supported vanadium oxide catalysts

Cited by 48 publications

References 1 publication

Monolayer V2O5/TiO2–ZrO2 catalysts for selective oxidation of o-xylene: preparation and characterization

Monolayer V2O5/TiO2–ZrO2 catalysts for selective oxidation of o-xylene: preparation and characterization

Characterization of V2O5/TiO2−ZrO2 Catalysts by XPS and Other Techniques

An XPS study of dispersion and chemical state of MoO3 on Al2O3-TiO2 binary oxide support

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Characterization of V₂O₅/TiO₂−ZrO₂ Catalysts by XPS and Other Techniques