Preparation Of Homogeneous Catalysts Grafted On Carbon Nanotubes And Its Catalytic Activity In Phenol Hydroxylation

Carbon nanotubes (CNTs) has drawn much attention as a potential catalytic material from a viewpoint of both fundamental research and industrial uses owing to their outstanding mechanical characteristics,such as high surface area,high tensile strength,good thermal conductivity and high electric conductivity. There are few reports of homogeneous catalysts supported on carbon nanotubes in despite of a lot of investigations about carbon nanotubes loading with metals. As excellent catalysts in organic oxidation reactions, palladium(II) and copper(II) catalysts perform high activities in phenol hydroxylation by hydrogen peroxide as oxidizing agent. It is important to research the catalytic properties of carbon nanotubes supporting homogeneous catalysts to extend the application fields of carbon nanotubes. The aim of this thesis is to study the preparation of homogeneous catalysts grafted on carbon nanotubes and its catalytic properties, and accumulate data for exploiting new type catalysts and developing their applications.The phenanthroline metal complex was tried to graft on the surface of multi-walled carbon nanotubes (MWNTs). The resultant catalysts were characterized by FTIR, SEM, TEM, XPS, TG-DTA, AAS, et al.With hydrogen peroxide as oxidizing agent, phenol was hydroxylated with catalysts of metal-phenanthroline complexes grafted on MWNTs. The products were qualitatively analyzed by HPLC. The catalytic performance of different catalysts and reaction conditions were examined. It was found that all of Pd (II), Cu (II)-phenanthroline grafted on MWNTs catalysts showed higher catalytic activities than pure multi-walled carbon nanotubes. The conversion of phenol and selectivity of dihydroxybenzene were influenced by the dosage of catalyst, reaction temperature, reaction time and so on. In phenol hydroxylation with Pd (II), Cu (II)-phenanthroline grafted on MWNTs catalysts, the conversion of phenol was 39.2% and the selectivity of dihydroxybenzene was 91.0% under the reaction conditions of 50℃, 4 h, 0.47 g phenol, 0.57 g H2O2, 20 ml H2O and 40 mg catalyst.