Development of heteroatom-doped graphene and boron nitride catalysts for the application to CO hydrogenation and selective oxidation of methane

Abstract

Enormous effort has been undertaken for the development of efficient catalyst to achieve low cost and high productivity of chemical process. As the outstanding influence of interrelation between metal and supports is revealed the support materials have been focused by many studies. Among various materials, graphene and boron nitride, which has graphene-analogous structure, have drawn massive attention due to many opportunities in heterogeneous catalysis. The studies referred to herein, contain design of effective catalysts by introducing heteroatoms into graphene and boron nitride. Optimizing the properties of a catalyst to obtain a desired level of catalytic activity is the goal of heterogeneous catalysis. Here, we tuned the catalytic activity via manipulating the electronic state of a catalyst, induced by facile doping method into graphene at metal/graphene system. Experimental results revealed that the electronic state of the catalyst was manipulated depending on the type, concentration, and doping structure of dopants. For CO hydrogenation reaction, the catalytic activities of metal/doped graphene catalysts were controlled toward increasing or decreasing way, up to 7.7 times, according to the electronic state of cobalt metal. It was revealed that change in the electronic state led to variations in the interactions between active metal and reactants by kinetic study and theoretical calculations, causing differences in catalytic performances. This strategy was proven to be applicable to not only transition metal and but also noble metal in other reaction such as 4-nitrophenol reduction. The selective oxidation of methane is one of the most attractive and challenging process in the chemical industry. Here, we synthesized boron nitride (BN)-based catalysts containing atomically dispersed Fe site by means of pyrolytic method. The isolated single Fe sites were distributed throughout defective BN which consists of the typical B3N3 hexagonal structure but randomly oriented layers. The unprecedented catalyst, Fe-embedded BN (0.8Fe-BN), exhibited remarkable methane conversion (27%) and formaldehyde selectivity (52%) at 873 K. In comparison with Fe nanoparticle, the single Fe site, which is coordinated to oxygen atoms in square-pyramidal structure, dominantly served as the crucial active site and contributed to the enhanced catalytic performance. These results may provide more opportunities for the use of BN materials for heterogeneous catalysis.