La2O3 nanorods - reduced graphene oxide composite as a novel catalyst for dimethyl carbonate production via transesterification route

Abstract

A highly efficient G/La heterogeneous catalyst comprising of reduced graphene oxide (rGO) and lanthanum oxide (La2O3) was developed using the in-situ hydrothermal technique. Four different catalyst samples with graphene content of 0.2, 0.5, 1.0, and 2.0 were prepared and tested against dimethyl carbonate synthesis (DMC) synthesis using the transesterification method. Structural analysis by scanning electron microscopy revealed that La2O3 displayed nanorod morphology. DMC synthesis results showed that G/La-3 composite with 1% graphene content outperformed others and showed the highest DMC yield of ~84% at 180 ºC. The excellent performance of G/La-3 was attributed to the synergistic effect of 2-D rGO and 1-D La2O3 nanorods, which showed the highest surface area of 76.54 m2/g. Moreover, the existence of acidic and basic active sites as identified by the temperature-programmed desorption (TPD) technique facilitates DMC production over the surface of G/La-3 catalyst. Recyclability and reusability experiments showed a gradual decrease in DMC yield owing to catalyst deactivation. It is expected that the present work provides valuable visions of the applicability of graphene/rare earth metal oxide heterogeneous catalysts in the given or similar chemical transformation processes.