Adsorption of Wells–Dawson tungsten heteropolyacid on sol–gel alumina: Structural features and thermal stability

Immobilization of Keggin and Preyssler tungsten heteropolyacids on various functionalized silica

“…4 and 5, has been investigated by UV-vis spectroscopy for an interval of 30-1440 min using a solution with a concentration of 0.25 and 0.1 mg of Keggin and Preyssler HPAs/ml, respectively. Kinetic adsorption of HPAs on functionalized silica, in contrast to alumina [25], is quite slow, but, for the Keggin type is faster than the Preyssler HPA. The amounts of Keggin and Preyssler HPA that adsorbed on the functionalized fume silica are about 1.5 and 1.6 mg/m 2 , respectively.…”

A DRIFTS Study of Catalyzed Dehydration of Alcohols by Alumina-supported Heteropoly Acid

“…The dehydration reaction can be catalyzed by various solid acid catalysts, such as heteropoly acid (HPA) [6][7][8][9][10][11][12]. Because of the advantages of supported heterogeneous systems compared to unsupported ones, the behavior and stability of Keggin-type HPAs on several supports have been investigated [7,8].…”

“…Alumina was selected as the support of HPA in this study, and investigations of HPA on other supports, such as silica, zeolite, and activated carbon are also in progress. For alumina-supported HPA catalysts, the formation of aluminum salt rather than the decomposition of the Keggintype structure has been suggested for 12-molybdophosphoric acid and 12-tungstosilicic acid [9][10][11][12]. Interestingly, it seems that H 4 SiW supported on alumina is an efficient catalyst for the conversion of methanol to hydrocarbons [12].…”

Wells–Dawson tungsten heteropolyacid-catalyzed reactions of benzylic alcohols, influence of the structure of the substrate

“…Recently, the Iranian team has investigated the characteristics of the Wells-Dawson tungsten heteropolyacid H 6 P 2 W 18 O 62 (1) and supported forms of this HPA [2] while, over the last 20 years, the French team was involved in metalcatalyzed reactions of alcohols [3,4]. This urged us to study the 1-catalyzed reactions of various benzylic alcohols; the results are here reported.…”