Acid—base properties of H3+nPVnMo12-nO40 heteropolyacids, pure and supported on K3PMo12O40

Serwicka, Ewa M.; Brückman, K.; Haber, J.; Paukshtis, E. A.; Yurchenko, É. N.

doi:10.1016/0166-9834(91)85133-g

Cited by 40 publications

(18 citation statements)

References 20 publications

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“…5). 70,71 Villabrille et al veried that equally to the observed herein, an increase in vanadium doping, lead to a diminution of the acidity strength of phosphomolybdic acids salts. 72 They attributed this effect to the increase in charge of heteropolyanion, with a consequent increase in the number of protons, reducing the acidity strength.…”

Section: Resultssupporting

confidence: 64%

Vanadium-doped sodium phosphomolybdate salts as catalysts in the terpene alcohols oxidation with hydrogen peroxide

et al. 2021

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Section: Resultssupporting

confidence: 64%

Vanadium-doped sodium phosphomolybdate salts as catalysts in the terpene alcohols oxidation with hydrogen peroxide

et al. 2021

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“…temperature programmed desorption (TPD) [33,34], FT-IR spectroscopy [35], calorimetry [36,37], (iii) pyridine ? TPD, FT-IR spectroscopy [38,39] and (iv) H 1 NMR [40] and O 17 NMR [41].…”

Section: Acidic Properties Of Heteropoly Acidsmentioning

confidence: 99%

Synthesis and Characterization of H3PW12O40 and H3PMo12O40 Nanoparticles by a Simple Method

et al. 2014

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In this study H 3 PW 12 O 40 Á9H 2 O and H 3 PMo 12 O 40 Á6H 2 O (HPA) particles were changed into nano forms by heat-treatment in an autoclave as a simple, repaid, inexpensive and one step method. The particle size of these nanoparticles was around 25 nm. The as-synthesized nanostructures were characterized by dynamic light scattering, X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and inductively coupled plasma analyzer. Thermal stability of nanoparticles was surveyed by thermal gravimeter analyse. Acidity of prepared nanoparticles was investigated by pyridine adsorption method. Results showed rising acidity by declining particle size of HPA.

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“…As this water may be absent under reaction conditions it is adequate to probe the acid-base properties of activated samples with a suitable method. The acidity of solid heteropoly compounds [38] has been investigated through interaction with bases combined with different methods of analysis: (i) Hammett indicators + visual inspection [39], (ii) ammonia + temperature programmed desorption (TPD) [40,41], IR spectroscopy [42], calorimetry [43,44], and (iii) pyridine + TPD, IR spectroscopy [45,46]. The use of Hammett indicators is difficult because many heteropoly compounds are strongly colored.…”

Section: Introductionmentioning

confidence: 99%

The structure of molybdenum-heteropoly acids under conditions of gas-phase selective oxidation catalysis: a multi-method in situ study

Jentoft

Klokishner

Kröhnert

et al. 2003

Applied Catalysis A: General

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The present study focuses on the evidence about the existence of Keggin ions under various reactive conditions. The stability of the hydrated parent heteropoly acid (HPA) phases is probed in water, by thermal methods in the gas phase, by in situ X-ray diffraction and in situ EXAFS. An extensive analysis of the in situ optical spectra as UV-Vis-NIR in diffuse reflectance yields detailed information about the activated species that are clearly different from Keggin ions but are also clearly no fragments of binary oxides in crystalline or amorphous form. Infrared spectroscopy with CO as probe molecule is used to investigate active sites for their acidity. Besides -OH groups evidence for electron-rich Lewis acid sites was found in activated HPA. All information fit into a picture of a metastable defective polyoxometallate anion that is oligomerised to prevent crystallisation of binary oxides as the true nature of the "active HPA" catalyst. The as-synthesized HPA crystal is thus a pre catalyst and the precursor oxide mixture is the final deactivated state of the catalyst.

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Acid—base properties of H3+nPVnMo12-nO40 heteropolyacids, pure and supported on K3PMo12O40

Cited by 40 publications

References 20 publications

Vanadium-doped sodium phosphomolybdate salts as catalysts in the terpene alcohols oxidation with hydrogen peroxide

Vanadium-doped sodium phosphomolybdate salts as catalysts in the terpene alcohols oxidation with hydrogen peroxide

Synthesis and Characterization of H3PW12O40 and H3PMo12O40 Nanoparticles by a Simple Method

The structure of molybdenum-heteropoly acids under conditions of gas-phase selective oxidation catalysis: a multi-method in situ study

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