Preparation of Tungstomolybdophosphate Acid with Dawson Structure and Its Catalytic Activity for the Synthesis of Adipic Acid via Hydrogen Peroxide Oxidaton of Cyclohexanone

Tungstomolybdophosphate acid with Dawson structure was prepared by hydrothermal synthesis and characterized by means of FT-IR,UV-Vis and TG-DTA.The synthesis of adipic acid from the reaction of cyclohexanone with 30% hydrogen peroxide under microwave irradiation was used as a probe to study the catalytic activity of tungstomolybdophosphate acid.The main effects of the reaction were optimized with orthogonal experiments.The results show that under the optimal conditions,i.e.the molar ratio of C6H10O∶H2O2∶ H2C2O4∶ H6P2W9Mo9O62·24H2O =100∶ 400∶ 1.25∶ 0.25,100 ℃ for the reaction temperature,400 W for the microwave power,and 3.5 h for the irradiation time,the isolated yield of adipic acid can reach 87.33% with a purity of 99.7%.The filtration containing the catalyst can be concentrated by the rotary evaporation and be reused five times by facile separation of the product after reaction,with an isolated yield of above 45.89% for adipic acid.