Photothermal oxidation of cyclohexane by graphene oxide-based composites with high selectivity to KA oil

Abstract

Designing high-performance catalyst for the oxidation of cyclohexane (CyH) into value-added products like cyclohexanol and cyclohexanone (the mixture called KA oil) is of paramount significance in chemical industry. Herein, the catalytic activity of graphene oxide coupled with Ag and Fe3O4 nanopaticles composites (GO-Ag&Fe3O4 NPs) was investigated to understand the synergistic effect between Ag and Fe3O4 NPs in photothermal oxidation of CyH. The comparative experiments between thermal and photothermal catalysis indicated that: (a) Conversion efficiency was facilitated by temperature rise, but less than 50 % of selectivity to KA oil was obtained at high temperature (140 °C); (b) Higher selectivity and milder condition were achieved by photothermal catalysis comparing to that of the thermal catalysis; (c) Ag NPs played more important role in photocatalysis, while thermocatalysis was intensified by Fe3O4 NPs. Using 1.5 MPa of dry air as oxidant, 6.6 % of CyH conversion with over 98 % of selectivity was gained by GO-Ag&Fe3O4 NPs. Additionally, no obvious decline in catalytic efficiency was observed after 5 cycles. The concept of photothermal cooperation for CyH oxidation over GO-Ag&Fe3O4 NPs may provide a new approach for the partial oxidation of saturated CH and the design of high-performance catalysts.