Catalytic oxidation of cyclohexanone to adipic acid catalysed by supported phosphotungstic acid

Adipic acid was synthesized via oxidation of cyclohexanone using phosphotungstic acid (H_3PW_(12)O_(40))/Al_2O_3 as the catalyst and 30% H_2O_2 as the oxidant.The influence of reaction condition on the yield of adipic acid was investigated.The optimum reaction condition was obtained as foUows: n (hydrogen peroxide):n (phosphoric acid):n (cyclohexanone) = 4.4:0.99:1,n(phosphotangstic acid): n(cyclohexanone) =1:290,reaction at 75 ℃ for 1 h and then at 93 ℃ for 7 h.Adipic acid yield of 95.5% was attained using with phosphoric acid as the promoter.Strength of the supported catalyst was enhanced by introduction of lanthanum.