Characterization of copper and vanadium containing heteropolyacid catalysts for oxidative dehydrogenation of propane

Bardin, Billy B.; Davis, Robert J.

doi:10.1016/s0926-860x(99)00174-x

Cited by 77 publications

(46 citation statements)

References 35 publications

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“…From Fig. 1, it can be seen Direct Hydroxylation of Benzene to Phenol 325 that PMoV n and PMoV n -b-CyDs (n = 1, 2) in this work showed all the IR vibration peaks assigned to a Keggin-type heteropolyacid, and the locations of featured peaks (PsO, 1,059 cm -1 ; MosOsMo, 959 cm -1 ; ModO, 870, 785 cm -1 ) are in well agreement with those in the previous report [33]. The prepared PMoV n (n = 1, 2) catalysts were orange-red in color, very soluble in water, and took on a blue color upon treatment with a mild reducing reagent, such as ascorbic acid.…”

Section: Catalyst Characterizationsupporting

confidence: 92%

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Direct Hydroxylation of Benzene to Phenol with Molecular Oxygen over Phase Transfer Catalysts: Cyclodextrins Complexes with Vanadium-Substituted Heteropoly Acids

Leng

Zhou

et al. 2008

Catal Lett

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Cyclodextrins (CyDs) complexes with vanadium-substituted heteropoly acids (PMoV n -b-CyDs, n = 1, 2) were prepared by simple mixing and their structures were characterized by FT-IR. Among various catalysts, PMoV 1 -b-CyDs, an efficient phase transfer catalyst, exhibited the highest yield (13.1%) of phenol without observing the formation of catechol, hydroquinone and benzoquinone in direct hydroxylation of benzene to phenol in 80 vol% aqueous acetic acid with molecular oxygen and ascorbic acid used as the oxidant and the reducing reagent, respectively. The influences of the reaction temperature, the pressure of oxygen, the amount of ascorbic acid, the amount of catalyst, and the reaction time on the yield of phenol were investigated to obtain the optimal reaction conditions for phenol formation.

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Section: Catalyst Characterizationsupporting

confidence: 92%

“…Keggin-type molybdovanadophosphoric acids (H 3+n PMo 12-n V n Á xH 2 O) were prepared at the P/Mo/V ratio of 1:(12 -n):n (n = 1, 2) using MoO 3 , V 2 O 5 , and aqueous 85% H 3 PO 4 as reactants [33]. For example, H 4 PMo 11 V was prepared as follows: MoO 3 (18.580 g, corresponding to 11.73 mmol Mo 11 ) (Shanghai Chem.…”

Section: Preparation Of Catalystsmentioning

confidence: 99%

Direct Hydroxylation of Benzene to Phenol with Molecular Oxygen over Phase Transfer Catalysts: Cyclodextrins Complexes with Vanadium-Substituted Heteropoly Acids

Leng

Zhou

et al. 2008

Catal Lett

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“…All reduced species with protons residing on the bridging oxygens listed in Tables 1 and 2 indicates an expel of vanadyl species based on the calculated peak maximum at 660/740 nm for HPA and 680/770 nm for Cs 2 A. These conclusions can also be drawn on the basis of observed absorption bands of VOSO 4 • 5H 2 O at 625 and 766 nm [34]. However, corresponding Raman bands indicating vanadyl species could not be observed for these catalysts treated in He [13].…”

Section: 4mentioning

confidence: 69%

“…Unfortunately, however, the title compound in particular with x = 0, is thermally unstable, which makes it especially difficult to determine the catalytically active center. Many efforts have been made to investigate the thermally unstable state, for example, by XRD [2,4], TG-DTA coupled with IMR-MS and DSC [2,5], IR [4,[6][7][8], EPR [9,10] and Raman [11][12][13]. To improve the stability and catalytic activity of such compounds, cations were introduced in the secondary structure [14,15].…”

Section: Introductionmentioning

confidence: 99%

UV/Vis/near-IR spectroscopic characteristics of H4–xCsxPVMo11O40 (x = 0, 2) catalyst under different temperatures and gas atmospheres

Melsheimer

Kröhnert

Ahmad

et al. 2002

Phys. Chem. Chem. Phys.

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In order to understand the transformations of the Keggin-type H4-xCsxPVMo11 (x=0,2) compounds with rising temperature over long time stream of different gas athmospheres, in situ UV/Vis/near-IR spectroscopic studies were carried out. Diffuse reflectance spectra were recorded using an improved spectrometer and a suitable microreactor. Visible and near-IR peak intensities, peak positions and the band gap energies were determined from apparent absorption spectra. Propene, iso-propanol, water and the oxidation products were analyzed by GC. The experimental observed blue shift of the visible absorption band in the range of crystal water loss and the increase of the near -IR absorption were explained on the basis of quantum-mechanical calculations of the shapes and positions of the charge transfer and d-d bands arising from Mo 5+ -Mo 6+ and V 4+ -Mo 6+ pairs in intact and ill-defined fragments of the Keggin structure. It was concluded that with removal of crystal water during the action of He, He/H2O, propene, O2/propene and increasing temperature reduced species with protons located at the bridging oxygens promote a blue shift of the visible band, while a large number of ill-defined species form the near-IR part of the spectra in the temperature range 326 -600 K.

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“…It is also well reported that partial substitution of vanadium for molybdenum is expected to enhance the oxidizing ability [7,8]. The effect of vanadium substitution for molybdenum in molybdophosphoric acid has been the subject of study by various authors [9][10][11]. A few reports are available on the synthesis of bulk vanadium substituted molybdphosphoric acid and its ammonium salt [12,13].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Zirconia Supported Vanadium Incorporated Ammonium Salt of 12-molybdophosphoric Acid Catalyst for Aerobic Oxidation of Benzyl alcohol

et al. 2007

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A series of zirconia supported ammonium salt of molybdophosphoric acid (AMPV) catalysts with and with out vanadium incorporation are prepared in a single step adopting wet impregnation method. These catalysts are characterized by BET surface area, XRD, FT-IR and potentiometric titration. XRD and FT-IR techniques suggest the formation of Keggin ion on zirconia support. The high resolution FT-IR analysis reveals the incorporation of vanadium into the primary structure of Keggin ion. The catalytic functionalities of these catalysts are tested for the aerobic oxidation of benzyl alcohol. The vanadium containing AMPV results in higher selectivity towards the oxidation product compared to the catalyst without vanadium incorporation.

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Characterization of copper and vanadium containing heteropolyacid catalysts for oxidative dehydrogenation of propane

Cited by 77 publications

References 35 publications

Direct Hydroxylation of Benzene to Phenol with Molecular Oxygen over Phase Transfer Catalysts: Cyclodextrins Complexes with Vanadium-Substituted Heteropoly Acids

Direct Hydroxylation of Benzene to Phenol with Molecular Oxygen over Phase Transfer Catalysts: Cyclodextrins Complexes with Vanadium-Substituted Heteropoly Acids

UV/Vis/near-IR spectroscopic characteristics of H4–xCsxPVMo11O40 (x = 0, 2) catalyst under different temperatures and gas atmospheres

Synthesis and Characterization of Zirconia Supported Vanadium Incorporated Ammonium Salt of 12-molybdophosphoric Acid Catalyst for Aerobic Oxidation of Benzyl alcohol

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