Tungstate catalysts, heterogenization

One problem associated with the peroxotungstate-catalyzed epoxidation system described above is the separation of the catalyst after the completed reaction. To overcome this obstacle, efforts to prepare heterogeneous tungstate catalysts have been conducted. De Vos and coworkers employed W catalysts derived from sodium tungstate and layered double hydroxides (LDH - coprecipitated MgCU, AICI3, and NaOH) for the epoxidation of simple olefins and allyl alcohols with... 

Buonomennna, M.G., Lopea, L.C., Barbieri, G., Favia, P., d Agostino, R. and Drioli, E. (2007) Sodium tungstate immobilized on plasma-treated PVDF membranes new efficient heterogeneous catalyst for oxidation of secondary amines to nitrones. Journal of Molecular Catalysis. A, Chemical, 273, 32-38, 10.1016/... 

Surface Vanadate, Molybdate and Tungstate Species The pure and mixed oxides and the salts of vanadium, molybdenum and tungsten in their higher oxidation states are used widely as heterogeneous catalysts, for selective oxidation as well as for acid catalysis. Similarly, supported chromia and rhenium oxides find wide application in different catalytic processes. 

Various heterogeneous catalysts have also been investigated for this reaction. Tetrahedral tungstate units can be incorporated at the surface of mesoporous silica, for example, S BA-15, to obtain heterogeneous systems that can effectively oxidize cyclohexene with HP [35a]. A 46% selectivity to colorless, crystalline AA was obtained at 85 °C, with total conversion of cyclohexene, under organic, solvent-free conditions. 

Tungstate Sulfuric Acid as a New Heterogeneous Solid Acid Catalyst..69... 

TUNGSTATE SULFURIC ACID AS A NEW HETEROGENEOUS SOLID ACID CATALYST... 

In 2010, Zubir, et al. investigated the kinetic behavior of the heterogeneous catalyzed esterification of oleic acid with ethanol using tungstated zirconia as a catalyst in the temperature range of 303.15- 323.15K (Otera, 1993). 

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