Heteropoly compound

H3PW12O40 is one of the most common heteropoly compounds. A distinct X-ray diffraction pattern is seen for H3PWi2O40.6H2O, where the Keggin units are linked by H+(H20)2 bridges, resulting in a body-centered cubic structure and hence the X-ray diffraction pattern. The water molecules can be easily replaced by a number of polar molecules such as alcohols and amines (Misono, 1987). 

Sanderson, Chemical Bonds and Bond Energy, Academic Press, New York, 1976. 

Yamaguchi, K. Miyamoto, H. Ohyama, M. Misono, Proc. 7th Intern. Zeolite Conf. 1986, (Y. Murakami at a/., eds.), Kodansha, Tokyo and Elsevier, Amsterdam, 1986, p.495. 

Csicsery, in Zeolite Chemistry and Catalysis (J. A. Rabo, ed.) American Chemical Society, 1976, 

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ELEMENT PROFILE OF TABACO PLANTS AFTER THE TREATMENT WITH HETEROPOLY COMPOUNDS WITH ANTIVIRAL ACTIVITY INVESTIGATED BY EDXRF SPECTROMETRY... 

In 1826 J. J. Berzelius found that acidification of solutions containing both molybdate and phosphate produced a yellow crystalline precipitate. This was the first example of a heteropolyanion and it actually contains the phos-phomolybdate ion, [PMoi204o] , which can be used in the quantitative estimation of phosphate. Since its discovery a host of other heteropolyanions have been prepared, mostly with molybdenum and tungsten but with more than 50 different heteroatoms, which include many non-metals and most transition metals — often in more than one oxidation state. Unless the heteroatom contributes to the colour, the heteropoly-molybdates and -tungstates are generally of varying shades of yellow. The free acids and the salts of small cations are extremely soluble in water but the salts of large cations such as Cs, Ba" and Pb" are usually insoluble. The solid salts are noticeably more stable thermally than are the salts of isopolyanions. Heteropoly compounds have been applied extensively as catalysts in the petrochemicals industry, as precipitants for numerous dyes with which they form lakes and, in the case of the Mo compounds, as flame retardants. 

Heteropoly compounds of molybdenum and tungsten. G. A. Tsigdinos, Top. Curr. Chem., 1978,... 

It is clear that the V-P oxide and Mo-P heteropoly compound catalysts are not effective for the production of citraconic anhydride. The acidic catalysts such as... 

Catalysis by Heteropoly Compounds. XXVII. Part XXVI S. Shikata,... 

Greater durability of the colloidal Pd/C catalysts was also observed in this case. The catalytic activity was found to have declined much less than a conventionally manufactured Pd/C catalyst after recycling both catalysts 25 times under similar conditions. Obviously, the lipophilic (Oct)4NCl surfactant layer prevents the colloid particles from coagulating and being poisoned in the alkaline aqueous reaction medium. Shape-selective hydrocarbon oxidation catalysts have been described, where active Pt colloid particles are present exclusively in the pores of ultramicroscopic tungsten heteropoly compounds [162], Phosphine-free Suzuki and Heck reactions involving iodo-, bromo-or activated chloroatoms were performed catalytically with ammonium salt- or poly(vinylpyrroli-done)-stabilized palladium or palladium nickel colloids (Equation 3.9) [162, 163],... 

Tsigdinos, G. A. Heteropoly Compounds of Molybdenum and Tungsten. 76, 1-64 (1978). Tsigdinos, G. A. Sulfur Compounds of Molybdenum and Tungsten. Their Preparation, Structure, and Properties. 76, 65-105 (1978). 

I4M. Misono, Heterogeneous Catalysis by Heteropoly Compounds of Molybdenum and Tungsten, Catalysis Reviews, 29,269-321 (1987). 

Acidity, 27 284, 285 catalytic performance, 30 121 crystalline titanium silicates, 41 319-320 estimating, 37 166 heteropoly compounds, 41 139-150 ion exchange and, zeolites, 31 5-6 sulfate-supported metal oxides, 37 186-187 surface, monolayer dispersion, 37 34-35 tin-antimony oxide, 30 114-115, 125-1256 Acids, see also specific compounds adsorption of, on oxide surfaces, 25 243-245... 

Heterogenous reactions, Sh/Nu ratio, 27 64 Heteroligand complex, 32 260-262 Heteropolyacids defined, 41 117 heteroatoms, 41 118, 120, 121 Prins reaction, 41 156 supported, 41 149-150 Heteropolyanions, 41 113, 117, 119-121 Heteropoly blues, 41 191 Heteropoly compounds absorption, 41 179-180, 190-191 acid-catalyzed reactions heterogeneous, 41 161-178 liquid phase, 41 150-161 acidic properties in solid state, 41 141-150 in solution, 41 139—14] catalysis, 41 114, 116-117, 190-191 as catalyst, 41 113-116, 117, 223-232... 

Cu in solid solution, 31 259-260 Scanning tunneling microscopy chemisorbed hydrocarbons on metals, 41 30 heteropoly compounds, 41 137 molecular precursors for tailored metal catalysts, 38 303-305... 

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