Continuous synthesis of carbon nanotubes using chemical vapor deposition in fluidized beds

This thesis work was focused on determining some parameters for synthesis of carbon nanotubes using Chemical Vapor Deposition (CVD) and continuous production of carbon nanotubes. In order to produce carbon nanotubes fluidized-bed reactor (with an inner diameter of 0.05 m a height of 1 meter) was designed and hydrodynamic parameters were determined. Then, Fe/Silica catalyst was synthesized and characterized by X-Ray Fluorescence (XRF). Carbon nanotubes were produced by the fluidized bed CVD. In these experiments, iron content of the most efficient catalyst was found as % 5.2. As a result of experiments, the best synthesis gas mixture was observed as (CO + H2). When acetylene was used as the carbon source, optimum reaction time and temperature were 90 minutes and 700 °C. They were 30 minutes and 800 °C, respectively, for synthesis gas. The purification experiments were performed by multi-step method which includes ultrasonication and acid washing. First step was to remove amorphous carbon structures from samples by sonication in H2O2 solution for half an hour at 50ºC. Following step was to remove metallic impurities using HCl solution and magnetic stirring at 70ºC for 4 hours. Finally, characterization of the products was performed by High-Resolution Transmission Electron Microscopy (HR-TEM).