Abstract
A series of keggin-type polyoxometalates namely; H3PMo12O40, H3PW12O40, Fe1.5PW12O40 and Co1.5PW12O40 were prepared, characterized and tested for the oxidation of cyclohexene by molecular oxygen in acetonitrile medium. The oxidation gives 2-cyclohexen-1-ol, 2-cyclohexen-1-one and cyclohexene oxide, however, 2-cyclohexen-1-one was the major product. The Co1.5PW12O40 catalyst showed the highest catalytic activity for the oxidation reaction and it was chose to study the effect of varying O-2 pressure, time, temperature and catalyst weight. The highest percentage of cyclohexene conversion and selectivity of the major product 2-cyclohexen-1-one was obtained at 5bar of O-2 pressure, 4h, 70 degrees C, and 900mg of Co1.5PW12O40 catalyst.