Photocatalyzed oxidation of cyclohexane with heterogenized decatungstate

Abstract

The application of heterogeneous catalysis to the oxidation of alkanes in mild conditions still remains a challenge although in the last decade many interesting approaches were proposed and examined delivering numerous significant results. Following our interest in C–H bond activation by photocatalysis with sodium decatungstate research on the possibility of its heterogenization on ion-exchange organic resins and a carbon material was undertaken. The photocatalytic activity of obtained heterogenized decatungstate for cyclohexane oxidation with molecular oxygen was examined. It was found that the highest activity was observed for decatungstate supported on an ion-exchange resin. The decatungstate concentration and loading effect on the reaction progress and selectivity was investigated. Catalyst loading on the support, contrary to catalyst concentration in the irradiated solution, determined the oxidation selectivity, i.e. the formation of cyclohexanone, cyclohexanol and cyclohexyl hydroperoxide. The lower loading of decatungstate promoted cyclohexanone production whereas the catalysts of high decatungstate loading favoured cyclohexyl hydroperoxide generation.