Synthesis of solid superacid of tungsten oxide supported on zirconia and its catalytic action for reactions of butane and pentane

Hino, Makoto; Arata, Kazushi

doi:10.1039/c39880001259

Cited by 283 publications

(177 citation statements)

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“…VO x , MoO x , and WO x contain electron-deficient cations that act as Lewis acid centers and WO x /ZrO 2 has been widely studied as an acid catalyst. 43,44 Lewis acid strength can be related to the electronegativity of each element in a compound and to the ratio of the square of the charge (q) to the ionic radius (r) for a given cation. In general higher electronegativity and larger q 2 /r values are associated with stronger Lewis acids.…”

Section: Resultsmentioning

confidence: 99%

Kinetics and Mechanism of Oxidative Dehydrogenation of Propane on Vanadium, Molybdenum, and Tungsten Oxides

2000

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The effect of cation identity on oxidative dehydrogenation (ODH) pathways was examined using two-dimensional VO x , MoO x , and WO x structures supported on ZrO 2 . The similar kinetic rate expressions obtained on MoO x and VO x catalysts confirmed that oxidative dehydrogenation of propane occurs via similar pathways, which involve rate-determining C-H bond activation steps using lattice oxygen atoms. The activation energies for propane dehydrogenation and for propene combustion increase in the sequence VO x /ZrO 2 < MoO x /ZrO 2 < WO x /ZrO 2 ; the corresponding reaction rates decrease in this sequence, suggesting that turnover rates reflect C-H bond cleavage activation energies, which are in turn influenced by the reducibility of these metal oxides. Propane ODH activation energies are higher than for propene combustion. This leads to an increase in maximum alkene yields and in the ratio of rate constants for propane ODH and propene combustion as temperature increases. This difference in activation energy (48-61 kJ/mol) between propane ODH and propene combustion is larger than between bond dissociation enthalpies for the weakest C-H bond in propane and propene (40 kJ/mol) and it increases in the sequence VO x /ZrO 2 < MoO x /ZrO 2 < WO x /ZrO 2 . These results suggest that relative propane ODH and propene combustion rates depend not only on C-H bond energy differences but also on the adsorption enthalpies for propene and propane, which reflect the Lewis acidity of cations involved in π bonding of alkenes on oxide surfaces. The observed difference in activation energies between propane ODH and propene combustion increases as the Lewis acidity of the cations increases (V 5+ < Mo 6+ < W 6+ ).

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Section: Resultsmentioning

confidence: 99%

Kinetics and Mechanism of Oxidative Dehydrogenation of Propane on Vanadium, Molybdenum, and Tungsten Oxides

2000

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“…Since Hino and Arata have developed zirconium oxide supported tungsten-oxide (WZ; WOx _ ZrO2) catalysts promote n-butane isomerization even at ambient temperatures 22), 23) , such WZ catalysts are very interesting because of the remarkable strong acidity, high thermal stability up to 1100 K, easy preparation procedures and handling, and anomalous acidity generation mechanisms 21) ,24) 27) . The activity is strongly dependent on the loading amounts and calcination temperature.…”

Section: )mentioning

confidence: 99%

X-ray Absorption Spectroscopic Characterization of Solid Acid-base Catalysts

Yamamoto

2014

J. Jpn. Petrol. Inst.

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Recent X-ray absorption spectroscopic studies of solid acid-base catalysts were reviewed, which have been carried out to investigate the effects of lanthanum-ion addition to alumina for improving the thermal stability, acidity generation mechanism of siliceous mesoporous silica, or state of tungsten oxide species in WOx _ ZrO2 strong solid acid. Remarks on EXAFS analytical procedures were also discussed about possibility of coexistence of multiple phases, mismatch between radial distribution functions and Fourier transforms of EXAFS, and effects of multiple excitations in an X-ray absorption spectrum.

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“…Among these modified zirconia, tungsten-deposited zirconia is the most interesting candidate because the sulfated zirconia undergoes partial deactivation due to sulfate loss during thermal treatment, 10 while the molybdenumdoped zirconia is a less active catalyst. Since the first work of Hino and Arata 11,12 demonstrating the use of tungsten-deposited zirconia as a solid acid for isomerization of light alkanes, several reactions such as oxidative desulfurization, 13 alkylation of phenols, 14 o-xylene isomerization, 15 production of aromatics from alkylfurans, 16 2-butanol dehydration, 17 among others, have been catalyzed by these materials. Herein, we focus on the industrially relevant aldoxime dehydratation and alkyne hydration reactions, for the synthesis of nitriles and carbonyl compounds, respectively.…”

Section: Introductionmentioning

confidence: 99%

One step microwave-assisted synthesis of nanocrystalline WO_x–ZrO₂ acid catalysts

Gonell

Portehault

Julián‐López

et al. 2016

Catal. Sci. Technol.

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Nanocrystalline ZrO2 and WOx-ZrO2 catalysts with a good control over the zirconia phase and the nature of the W species were synthesized in a microwave-assisted aqueous route. The zirconia polymorphs monoclinic ZrO2 (m-ZrO2) and tetragonal ZrO2 (t-ZrO2) were isolated through an accurate control of the synthetic conditions, in acidic and basic media, respectively.The evolution of the zirconia and W species under annealing of the WOx-ZrO2 nanocomposites at 500 o C and 800 o C was studied, and the resulting materials were tested as catalysts for the reactions of aldoxime dehydration and hydration of alkynes for the production of nitriles and carbonyls, respectively. In the dehydration reaction the most active species are W(VI) in tetrahedral coordination, independently of the ZrO2 polymorph, while in the hydration reaction the zirconia phase plays a key role, as the tungsten doped t-ZrO2 appears the most active catalyst.

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Synthesis of solid superacid of tungsten oxide supported on zirconia and its catalytic action for reactions of butane and pentane

Cited by 283 publications

References 0 publications

Kinetics and Mechanism of Oxidative Dehydrogenation of Propane on Vanadium, Molybdenum, and Tungsten Oxides

Kinetics and Mechanism of Oxidative Dehydrogenation of Propane on Vanadium, Molybdenum, and Tungsten Oxides

X-ray Absorption Spectroscopic Characterization of Solid Acid-base Catalysts

One step microwave-assisted synthesis of nanocrystalline WO_x–ZrO₂ acid catalysts

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Synthesis of solid superacid of tungsten oxide supported on zirconia and its catalytic action for reactions of butane and pentane

Cited by 283 publications

References 0 publications

Kinetics and Mechanism of Oxidative Dehydrogenation of Propane on Vanadium, Molybdenum, and Tungsten Oxides

Kinetics and Mechanism of Oxidative Dehydrogenation of Propane on Vanadium, Molybdenum, and Tungsten Oxides

X-ray Absorption Spectroscopic Characterization of Solid Acid-base Catalysts

One step microwave-assisted synthesis of nanocrystalline WOx–ZrO2 acid catalysts

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One step microwave-assisted synthesis of nanocrystalline WO_x–ZrO₂ acid catalysts