Characterization of supported vanadium oxide catalysts by a low-temperature oxygen chemisorption technique

Chary, Komandur V. R.; Rao, B. Rama; Subrahmanyam, V.S.

doi:10.1016/0166-9834(91)90004-r

Cited by 26 publications

(14 citation statements)

References 51 publications

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“…The values | g | = 1.968 and | A | = 118 are characteristic of vanadium in a distorted octahedral/square-pyramidal environment . Our average g values and hyperfine coupling constants (| g | and | A |) match with the values obtained by Chary et al for reduced samples of V 2 O 5 supported on zirconia. The higher values of B and hyperfine coupling constants A || and A ⊥ for the V/PZr samples indicate weaker interaction of V 2 O 5 with the PZr support in comparison to ZrO 2 .…”

Section: Resultssupporting

confidence: 87%

“…Eight resolved hyperfine lines may result from interaction between the 3d 1 electron ( S = 1 / 2 ) and the nuclear magnetic moment ( I = 7 / 2 ) of the vanadium atom. Vanadia supported on various carriers such as Al 2 O 3 , SiO 2 , TiO 2 , MgO, and ZrO 2 has been characterized by employing the ESR technique by various investigators. ,, The observance of clear hyperfine splitting is difficult in calcined samples if the spectra are recorded at ambient temperature, because of the predominance of spin−spin interactions or because of the presence of vanadium in an undistorted environment of oxygen atoms. When the recording temperature was lowered or when the sample was reduced in a hydrogen atmosphere, hyperfine splitting was observed.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, much attention is being focused on the use of metal-promoted sulfated zirconia for the skeletal isomerization of alkanes, disproportionation reactions, Fischer−Tropsch synthesis, etc. − Cr 2 O 3 supported on ZrO 2 was employed for hydrogenation of propene and oxidation of carbon monoxide. , CuO/ZrO 2 catalysts were employed in methanol synthesis from syngas . MoO 3 /ZrO 2 catalysts were found to be highly active and selective in catalyzing the oxidation reactions of lower olefins and alcohols. − Vanadia supported on zirconia was employed for catalyzing reactions such as partial oxidation, − oxidative dehydrogenation of propane, ammoxidation, and selective catalytic reduction of NO x . , Different characterization techniques such as X-ray diffraction (XRD), , electron spin resonance (ESR), 51 V solid-state nuclear magnetic reasonance (NMR), , and laser Raman spectroscopy , were employed earlier for the characterization of V 2 O 5 /ZrO 2 catalysts.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis, Characterization, and Activity Studies of Vanadia Supported on Zirconia and Phosphorus-Modified Zirconia

Lakshmi

Alyea

1999

Langmuir

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A series of catalysts with vanadia contents varying between 1 and 14 wt % were prepared by the wet impregnation technique on zirconia and phosphorus-modified zirconia. The catalysts were characterized by employing X-ray diffraction (XRD), electron spin resonance (ESR) spectroscopy, 51V, 31P, and 1H solid-state magic angle spinning nuclear magnetic resonance (MAS NMR), Fourier transform Raman spectroscopy (FT-Raman), diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS), and Brunauer−Emmett−Teller (BET) surface area measurements. The activities of the catalysts were determined by an ethanol partial oxidation reaction. 51V solid-state NMR studies of both series of catalysts indicated the presence of tetrahedral vanadate species at lower loadings, and octahedrally coordinated vanadium species at higher concentrations. DRIFTS studies of the catalysts were in conformity with NMR studies as the vibrations corresponding to tetrahedral vanadate species were observed at low V2O5 loadings and at higher vanadia contents the vibrations corresponding to polymeric decavanadate species were seen. All of the XRD, ESR, 51V solid-state NMR, FT-Raman, and DRIFTS results indicated weaker interaction of vanadia with zirconia support upon phosphate modification. Activity studies were in agreement with spectroscopic data, as reflected in higher ethanol partial oxidation activities of the V2O5/ZrO2 catalysts.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis, Characterization, and Activity Studies of Vanadia Supported on Zirconia and Phosphorus-Modified Zirconia

Lakshmi

Alyea

1999

Langmuir

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“…2±4 In recent years zirconia has attracted considerable interest because of its potential use as a catalyst support. 6±16 It has been employed in many industrially important reactions such as hydroprocessing, 8±10 oxidation of alcohols, 11,12 synthesis of methanol and higher alcohols, 13±15 and methanation reactions. 16 Here we report the synthesis of nicotinonitrile by the vapour phase ammoxidation reaction over highly dispersed vanadia catalysts supported on zirconia.…”

mentioning

confidence: 99%

Ammoxidation of 3-Picoline to Nicotinonitrile over Highly Dispersed V2O5/ZrO2 Catalysts†

Chary¹,

Kishan²,

Narayana³

et al. 1998

J. Chem. Res.

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“…Moreover, ZrO 2 is one of the most investigated transition metal oxide. Mesoporous ZrO 2 was extensively studied by the scientists in various industrial applications [27][28][29]. Nanostructured CuO has high catalytic applications due to its high surface-to-volume ration.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of mesoporous CuO/ZrO 2 -MCM-41 nanocomposites for photocatalytic reduction of Cr(VI)

Nanda

Pradhan

Parida

2017

Chemical Engineering Journal

103

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h i g h l i g h t sMesoporous ZrO 2 -MCM-41synthesized by in situ incorporation process. CuO@ZM-41 synthesized by modification of CuO onto the ZrO 2 -MCM-41. CuO@ZM-41nacomposite shows semiconductor behavior and mesoporosity. High surface area, lower e À and h + recombination are enhancing the photo-reduction. g r a p h i c a l a b s t r a c tMesoporous nanocomposite (CuO@ZM-41) is synthesized by incorporating mesoporous ZrO 2 (Z) into MCM-41 (M-41) framework followed by loading of CuO by wetness impregnation method. The synergism between CuO and the support material mesoporous ZM-41 and efficient light absorption on the surface of the composite is the key factor for the reduction Cr 6+ to Cr 3+ within 30 min time. a b s t r a c tMesoporous nanocomposites of CuO/ZrO 2 -MCM-41 (CuO@ZM-41) was designed by incorporating mesoporous ZrO 2 (Z) into the high surface area MCM-41 (M-41) framework followed by loading CuO by wetness impregnation method keeping Si/Zr ratio 10. The nanocomposites were studied under PXRD, N 2 sorption, DRS spectra, FTIR, XPS, NMR, HRTEM and PL to evaluate structural, morphological, optical properties and also the mesoporosity nature of the samples. The photo-reduction of Cr 6+ was performed over CuO@ZM-41 by varying pH, substrate concentration, and irradiation time and catalyst dose. Among all the catalysts, 2 CuO@ZM-41 was found to be efficient photocatalyst for the photo-reduction of Cr 6+ . Nearly 100% reduction of Cr 6+ has been achieved by 2 CuO@ZM-41 within 30 min. Intra-particle mesoporosity, high surface area, presence of CuO nanorods and electron transfer properties are the key factors for enhancing the photo-reduction activity of 2CuO@ZM-41.

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Characterization of supported vanadium oxide catalysts by a low-temperature oxygen chemisorption technique

Cited by 26 publications

References 51 publications

Synthesis, Characterization, and Activity Studies of Vanadia Supported on Zirconia and Phosphorus-Modified Zirconia

Synthesis, Characterization, and Activity Studies of Vanadia Supported on Zirconia and Phosphorus-Modified Zirconia

Ammoxidation of 3-Picoline to Nicotinonitrile over Highly Dispersed V2O5/ZrO2 Catalysts†

Fabrication of mesoporous CuO/ZrO 2 -MCM-41 nanocomposites for photocatalytic reduction of Cr(VI)

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