Preparation And Catalytic Performance Of Graphite - Based Catalysts

The discovery of graphene stirs up a great wave in the scientific community. Its broad application prospect in variety of fields have brought huge market with development value and commercial value. Graphene is therefore known as "the most magical material found in twenty-first century"due to its inestimable potential value for application. Graphene has a unique two-dimensional structure, huge specific surface area, high charge mobility, easy surface modification, good resistance to acid and base and high-temperature, which makes it be an excellent catalyst candidate. Thus, it has attracted much attention in the field of catalysis in recent years.Based on the above-mentioned background of graphene, we started a research on synthesis and catalytic activity evaluation of graphene-based materials. We designed and synthesized palladium nanoparticles supported on reduced graphene oxide nanosheets (SRGO-Pd) and applied it to aminocarbonylation of aryl halides. The studies revealed that graphene acted as a metal-free heterogeneous catalyst, and exhibited excellent catalytic activity in the above reaction. The main contents are enclosed in the following:(1) The SRGO-Pd composite was prepared by a facile solvothermal method using N,N-dimethylformamide(DMF). The SRGO-Pd was employed for the amino-carbonylation of aryl halides without using carbon monoxide. The characterization results revealed that palladium nanoparticles were uniformly anchored on the reduced graphene oxide nanosheets by solvothermal approach. Under DMF solvothermal conditions, the SRGO-Pd catalyst exhibited excellent catalytic activity and good recyclability for the aminocarbonylation reaction of aryl halides:the yield of the aminocarbonylation product is up to 98% and after eight recycles the catalytic activity of the catalyst remains.(2) A green metal-free catalytic system for the Friedel-Crafts alkylation reaction of indoles and aromatic aldehydes was developed based on the heterogeneous nature and appropriate acidity of graphite oxide. The result showed that the catalyst has high catalytic activity and selectivity for the formation of the desired product bis(indolyl)methane derivatives. The catalyst could be easily separated from the reaction system and was recycled. When the catalyst was recycled for 5 times, its catalytic activity was still kept up to 75% yield of the desired product.(3) The graphite oxide (GO) was found to be an efficient catalyst for the Mannich reaction of aromatic aldehydes, aromatic amines and aliphatic ketones in an aqueous solution with 87% yield of the β-amino ketones. The catalytic system features simple operation, wide tolerance to functional groups and excellent catalytic activity. Moreover, the catalyst can be easily separated from the reaction system for recycling.and the catalytic activity of the catalyst was remained with up to 80% product yield when the catalyst was used for five times.