αII-(V1-W )OPO4 catalysts for the selective oxidation of n-butane to maleic anhydride

Schulz, Christian; Roy, Subrata Chandra; Wittich, Knut; d’Alnoncourt, Raoul Naumann; Linke, Stefan; Strempel, Verena E.; Frank, Benjamin; Glaum, Robert; Rosowski, Frank

doi:10.1016/j.cattod.2018.05.040

Cited by 29 publications

(40 citation statements)

References 54 publications

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“…Details of the preparation and characterization of VWPO are described elsewhere. 29,31 The VPP catalyst was prepared according to patent literature via an organic route. 19 Briefly, V 2 O 5 was dissolved in H 3 PO 4 and reduced with isopropanol.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…A detailed description of the setup can be found elsewhere. 29 The conversion (X) of n-butane (eqs 1 and 3) and the selectivities (S) of the respective products (eqs 2 and 4) are calculated from the concentrations measured with reference to the internal standard Ar. The latter are averaged over 5 runs measured at each temperature step, respectively.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Selective Oxidation of n-Butane over Vanadium Phosphate Based Catalysts: Reaction Network and Kinetic Analysis

Schulz

Pohl

Drieß

et al. 2018

Ind. Eng. Chem. Res.

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The reaction network of n-butane selective oxidation was comparatively analyzed over a novel αII-V0.8W0.2OPO4 orthophosphate and a reference vanadyl pyrophosphate (VPP) based catalyst via parameter field studies (T = 360–420 °C, x(n-butane) = 0.5–2.0%, x(O2) = 10–20%) as well as cofeed and pulse experiments with presumed reaction intermediates. For VPP the selectivity to the target product maleic anhydride (MAN) is particularly sensitive to the reaction temperature, the n-butane concentration, and the amount of cofed H2O, whereas the selectivity to MAN over the W-containing catalyst is almost independent of all reaction parameters. The roles of 1-butene, acetylene, furan, acetaldehyde, water, and 2,5-dihydrofuran are discussed. Pulsing of possible C4 intermediates indicates that their desorption from the catalyst surface is detrimental to MAN selectivity. Ethylene and acetylene may be formed from MAN. The consecutive reaction of acetylene with H2O can lead to acetic acid, whereas all other byproducts are predominantly formed directly from n-butane. The pronounced stability of both samples was confirmed by repeated catalyst performance test under reference conditions, XRD, and SEM. Mass and heat transport limitations were experimentally excluded. A formal kinetic model including n-butane, MAN, CO, CO2, acetic acid, and acrylic acid was developed, in which the acids were found to be less relevant on the V0.8W0.2OPO4 catalyst. However, the main reaction pathways were found to be similar over both catalysts, which differ mainly in product selectivities.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Selective Oxidation of n-Butane over Vanadium Phosphate Based Catalysts: Reaction Network and Kinetic Analysis

Schulz

Pohl

Drieß

et al. 2018

Ind. Eng. Chem. Res.

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“…Pure VOPO4 is catalytically dead for the partial oxidation of n-butane to maleic anhydride however, only tungsten substituted VOPO4, (V1-xWx)OPO4; where 0 ≤ x ≤ 0.24 (αII-VOPO4 structure type) [Schulz et al 2018] leads to a new catalyst material for that purpose. Since the insertion of another redox active transition metal, niobium in presence of tungsten might increase this catalytic efficiency.…”

Section: Resultsmentioning

confidence: 99%

“…αII-VOPO4 structure could be stabilized by substitution of vanadium by tungsten in the range of 0.04 ≤ x ≤ 0.24 (Roy et al 2014). Moreover, partial substitution of "V" by "W" in αII-VOPO4 leads to promising catalyst material for butane based oxidation (Schulz et al 2018). Therefore to attain the αII-VOPO4 structure type solid solution the amount of "W" in the aiming product is taken 0.07.…”

Section: (Eq 2)mentioning

confidence: 99%

Synthesis and Characterization of Niobium and Tungsten Substituted VOPO4

Roy

Yeasmin

Rahman

2019

J Bangladesh Acad Sci

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Tungsten and Niobium substituted αII-VOPO4 structure type solid solution (V1–x-yWxNby) OPO4 where x = 0.07 and y ≤ 0.05 was synthesized by solution combustion technique followed by heating in air at 700˚C for 3 days. Further incorporation of niobium (y > 0.05) leads to a mixture of αII-VOPO4 structure type solid solution and two very weak reflections of another unknown phase. The synthesized product was characterized by X-ray powder diffraction, SEM/EDX, FTIR, and magnetic property analysis. Journal of Bangladesh Academy of Sciences, Vol. 43, No. 1, 31-37, 2019

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“…It was found that the catalytic reaction mechanism may involve vanadium in an intermediate oxidation state [4]. This, in turn, has encouraged experimental efforts to introduce mixed-valency in vanadyl phosphates, hoping for new catalyst materials [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Multi-Frequency and Single-Crystal EPR on V4+ in W-Doped β-Vanadyl(V) Phosphate: Hyperfine Coupling- and g-Tensor Values and Orientation

et al. 2021

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Different structure types of vanadyl(V) orthophosphate [i.e. (VV ≡O)3+ orthophosphate] have been subjects of research due to their catalytic activity in the oxidation of n-butane to maleic anhydride. Electron paramagnetic resonance (EPR) spectroscopy can be exploited to elucidate the electronic structure of such compounds. When tuning the oxidation state of vanadium in (V1-xWx)OPO4, X-band EPR spectra have confirmed the presence of paramagnetic V4+ ions. However, some of the features in these spectra could not be explained. Here, powder samples of β-(VIV0.01VV.98WVI.01)OPO4 are investigated at S-, X- and Q- band, along with X-band EPR measurements on single crystals. Thereby, the discrepancies between the spectra and their simulations could be resolved. In particular, it could be shown that the g and A tensors are not coaxial. The resulting consistent EPR picture and the refined paramagnetic parameters are reported. The work underlines the indispensability of a multi-frequency approach in EPR for unequivocal conclusions.

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αII-(V1-W )OPO4 catalysts for the selective oxidation of n-butane to maleic anhydride

Cited by 29 publications

References 54 publications

Selective Oxidation of n-Butane over Vanadium Phosphate Based Catalysts: Reaction Network and Kinetic Analysis

Selective Oxidation of n-Butane over Vanadium Phosphate Based Catalysts: Reaction Network and Kinetic Analysis

Synthesis and Characterization of Niobium and Tungsten Substituted VOPO4

Multi-Frequency and Single-Crystal EPR on V4+ in W-Doped β-Vanadyl(V) Phosphate: Hyperfine Coupling- and g-Tensor Values and Orientation

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