Synergistic effect of iron and copper oxides supported on silica in the room temperature oxidation of cyclohexane Original Research Article

The room temperature oxidation of cyclohexane with oxygen/zinc (GifIV system), catalysed by iron oxide supported on silica, has been studied. It was found that after calcination the iron catalyst does not leach and is very active for oxidation. Using 4 mmol of iron chloride per 0.1 g of silica, cyclohexanone and cyclohexanol (2:1 ratio) were obtained with a turnover number of 425. Substitution of half of the iron used for impregnation by copper chloride increased the turnover number to 885, without changing the product ratio. As copper chloride alone is not active for this reaction, it exhibits a synergistic effect on the iron(III) heterogenized on the silica.