Synthesis And Catalytic Oxidation Of Alcohols Performance Of Dawson Type Multi-component Heteropoly Compounds

Based on Dawson-type heteropoly compound P₂W₁₈, a series of metal-substituted the lacunary Dawson-type tungstophosphoric and molybdotungstophosphoric were synthesized. The Dawson-type niobium and pyridine-exchanged molybdovanadophosphate complex was synthesized. The results of IR, UV-vis spectroscopy and DTA-TGA confirmed that all compounds still remain basically characteristic of the Dawson structure. The Dawson-type compounds were used in the catalytic selective oxidation of benzyl alcohol and catalytic activity was investigated systematically.Metal-substituted the lacunary Dawson-type heteropolyanions exhibited high catalytic activity and selectivity for catalytic oxidation of benzyl alcohol with H₂O₂. In particularly,α₂-MgP₂W₁₇ had a high catalytic activity. The reaction condition and catalytic activity was investigated , and the optimization reaction conditions were obtained.When H₂O₂ was used as the oxidation, water as solvent and metal-Substituted the lacunary Dawson-type heteropolyanions molybdotungstophosphoric as catalyst, the reaction condition of catalytic oxidation of benzyl alcohol was investigated by orthogonal design. Optimization reaction conditions were obtained through analyzing results of orthogonal design.A series of Wells-Dawson type niobium and pyridine-exchanged molybdovanadophosphate was synthesized and used in the catalytic oxidation of alcohol. The results indicated that NbH₂P₂Mo₁₆V₂pry had a high catalytic efficiency. When NbH₂P₂Mo₁₆V₂pry was used as catalyst , many primary and secondary alcohols could be converted to the corresponding carbonyl compounds with good to excellent conversion and selectivity. Moreover, this biphasic system based on NbH₂P₂Mo₁₆V₂pry permits extensive recycling of the catalyst without significant loss in activity and the uses of water as solvent and H₂O₂ as oxidant. From our present results, the high catalytic activity of NbH₂P₂Mo₁₆V₂pry was probably related to the cooperation of niobium and pyridine and the presence of appropriate vanadium as well as the structure of polyanion.