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Tungstophosphate

Tungstocobaltate and 12-Tungstophosphate Ions in Acidic Aqueous Solution. 630... [Pg.607]

Heteropolyacids are prepared in solution by acidifying and heating in the appropriate pH range (], 49-54). For example, 12-tungstophosphate is formed according to Eq. (1). Free acids are synthesized primarily by the following two methods (1) by extraction with ether from acidified aqueous solutions and (2) by ion exchange from salts of heteropolyacids. Dawson-type heteropolyanions,... [Pg.126]

Several compounds of tungsten, which is a transition metal closely related to molybdenum, are able to catalyze the selective oxidation of secondary alcohols with hydrogen peroxide as secondary oxidant. These include tris(cetylpyridinium) 12-tungstophosphate,33 peroxotungstopho-sphate (PCWP)34 and Na2W04 in the presence of a phase transfer catalyst.35 Tungstophosphoric acid is able to catalyze the selective oxidation of secondary alcohols in the presence of ferric nitrate as secondary oxidant.36... [Pg.346]

The potassium salt, similar manner by adding potassium carbonate to a suspension of the potassium 12-tungstophosphate until a clear solution is obtained. [Pg.253]

A series of salts obtained by the addition of hydrochloric acid to mixtures of alkali tungstates and alkali phosphates have been described by Gibbs, w ho formulates them, 3R 0.P205.22W0g.a H20. From their mode of ])reparation and reactions these salts appear to be more related to the 12-tungstophosphates than to the salts just described. Their composition, however, is not established. [Pg.253]

Tungstophosphoric Acid, (PoOj WO..= l 20), and corresponding salts have been described by several authors, but their e.xistenee is open to doubt. From the properties of the compounds described, and the methods used for their preparation, it would appear probable that they are identical with the 12-tungstophosphates. [Pg.254]

Lapham and Moffat [29] studied the influence of preparative parameters over several heteropolyoxometalates but the emphasis was put on 12-tungstophosphates. The role of thermal treatment was underlined and it was shown that the higher the tenperature, the lower the surface area. In this context, cesium salts were much more stable than other heteropolysalts. [Pg.482]

Trisodium 12-tungstophosphate hydrateNa3pW 2O40.12H2O TFXA 74... [Pg.589]

The experimental data and appropriate calculations from measurement of the adsorption of nitrogen at 78 K on ammonium 12-tungstophosphate have confirmed the presence of a microporous structure (refs. 20, 22). [Pg.570]

Heteropolyacids can also be bound to support materials by direct deposition. More firmly bonded materials can be prepared through chemical surface modification. Acids such as 12-tungstophosphate (PW12) will react with silica gels which have been treated with aminoalkylsilanes.129 The acidic site of PW12 reacts with the chemically modified surface forming ionic bonds. The latter... [Pg.87]


See other pages where Tungstophosphate is mentioned: [Pg.1087]    [Pg.1089]    [Pg.1094]    [Pg.1087]    [Pg.1089]    [Pg.1094]    [Pg.208]    [Pg.160]    [Pg.22]    [Pg.42]    [Pg.576]    [Pg.987]    [Pg.1154]    [Pg.1160]    [Pg.158]    [Pg.291]    [Pg.486]    [Pg.601]    [Pg.141]    [Pg.761]    [Pg.348]   


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Tungstophosphates

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