Sandwich-type cobalt tungstophosphate: Synthesis, characterization and catalytic activity
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Sandwich-type cobalt tungstophosphate, Oxidation, Cyclooctane, Hydrogen peroxideบทคัดย่อ
odium tungstophosphate, Na9[HPW9O34].7H2O was synthesized by reaction in aqueous solution of sodium tungstate, phosphoric acid and acetic acid. It was used as a precursor for synthesis of sandwich-type cobalt tungstophosphate, K10[Co4(H2O)2(PW9O34)2].20H2O by reacting with cobalt chloride and potassium acetate. The potassium ion can be exchanged with tetrabutylammonium bromide. The characterization was carried out by means of elemental analysis, FT-IR, UV-vis diffuse reflectance spectroscopy (DR-UV-vis). The sandwich-type cobalt tungstophosphate was used to catalyze oxidation of cyclooctane with H2O2 as oxidant in absence and presence of phase transfer agent. The experimental results showed that with phase transfer agent, the sandwich-type cobalt tungstophosphate effectively catalyzed oxidation of cyclooctane, yielding high conversion and selectivity to cyclooctanone. The experiment with radical trap suggests the involvement of a free-radical mechanism.Downloads
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