1992
DOI: 10.1051/jcp/1992890435
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Characterization by 51V solid state NMR of vanadium in dehydrated H4PVMo11O40 and Na1.5H2.5PVMo11O40 catalysts

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Cited by 21 publications
(14 citation statements)
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“…For example, the rate of reduction by hydrogen is slower and less reversible for solid PMo 12 - x V x O 40 (3+ x )- than for solid PMo 12 O 40 3- although in solution the former systems are stronger oxidants than the latter . The thermal treatment of H 4 PMo 11 VO 40 formed PMo 12 O 40 3- and VO 2+ and the reduction of H 4 PMo 11 VO 40 with isobutyric acid formed PMo 12 O 40 4.09- , VO 2+ , PO 4 3- , and methacrylic acid. , These decomposition reactions are deeply related to the controversy about the effects of substitution by V for Mo on the catalytic activity. ,,− It is also unclear why the rate of reduction decreases with the content of alkali cation …”
Section: Effects Of Constituent Elements On the Redox Propertiesmentioning
confidence: 99%
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“…For example, the rate of reduction by hydrogen is slower and less reversible for solid PMo 12 - x V x O 40 (3+ x )- than for solid PMo 12 O 40 3- although in solution the former systems are stronger oxidants than the latter . The thermal treatment of H 4 PMo 11 VO 40 formed PMo 12 O 40 3- and VO 2+ and the reduction of H 4 PMo 11 VO 40 with isobutyric acid formed PMo 12 O 40 4.09- , VO 2+ , PO 4 3- , and methacrylic acid. , These decomposition reactions are deeply related to the controversy about the effects of substitution by V for Mo on the catalytic activity. ,,− It is also unclear why the rate of reduction decreases with the content of alkali cation …”
Section: Effects Of Constituent Elements On the Redox Propertiesmentioning
confidence: 99%
“…47,48 These decomposition reactions are deeply related to the controversy about the effects of substitution by V for Mo on the catalytic activity. 47,48,[136][137][138][139][140] It is also unclear why the rate of reduction decreases with the content of alkali cation. 105…”
Section: Effects Of Constituent Elements On the Redox Propertiesmentioning
confidence: 99%
“…62 Moreover, an increase in the replacement level of Mo by V atoms triggered changes in the infrared spectra, which was induced by a decrease in the symmetry of the heteropolyanion. 63,64 Particularly, the splitting of P-O a bond stretching band (ca. 1080 cm À1 ), as well as the presence of shoulders were more noticeable in the vanadium-trisubstituted phosphomolybdate anion.…”
Section: Resultsmentioning
confidence: 99%
“…A slight shi toward lower frequencies of main absorption bands was also noticed if compared to the infrared spectrum of the Na 3 PMo 12 O 40 salt 62. Moreover, an increase in the replacement level of Mo by V atoms triggered changes in the infrared spectra, which was induced by a decrease in the symmetry of the heteropolyanion 63,64. Particularly, the splitting of P-O a bond stretching band (ca.…”
mentioning
confidence: 81%
“…Oxo–vanadium bonding in the Keggin unit is strongly destabilized in the acid form. Removal of the “crystalline” water molecules from the secondary structure (see Scheme S1), without having an alternative cation present (e.g., Na + , K + ), initiates destruction of the primary structure by expulsion of vanadium giving a lacunary (defective) Keggin. Expulsion of pentavalent vanadium nuclei from PVMo 11 is usually accompanied by rapid one-electron reduction to paramagnetic V 4+ .…”
Section: Introductionmentioning
confidence: 99%