The Preparation Of Carbon Nanomaterials With Coal Gas As Carbon Feedstock Via CVD Technique

Recently, nano-technology has been developing with an unprecedented speed in high-tech areas which arouses great interests and deep investigation. As one of the earliest research fields, carbon nanomaterials attract more and more attention.Among the diverse approaches to preparing carbon nanomaterials, such as arc discharge, chemical vapor deposition, laser ablation, etc., chemical vapor deposition (CVD) is a widely employed technique due to its facileness and effectiveness. It is originally a common used technique in industry for synthesis of a variety of materials, such as a majority of insulation materials, most metal materials and alloy materials. It is believed that CVD is not only an important technique to synthesize various carbon nanomaterials, such as carbon nanotubes, carbon nanofibers and filled cabon nanomaterials, etc., but also the sole method for industrial production of carbon nanomaterials.Herein, via CVD technique, we successfully prepared several kinds of carbon nanomaterials with coal gas as carbon feedstock which is a kind of pipe gas for household and civil use supplied by Dalian Coal Gas Company. The contents of the thesis include: the synthesis of carbon nano spheres by non-catalytic CVD, the production of ferromagnetic filled carbon nanotubes and nanoparticles with ferrocene as the catalyst, the preparation of herringbone carbon nanofibers on metal-contained silica substrates and bamboo-like carbon nanotubes with FeNi alloy as catalysts. Besides, the factors in determining the morphology of the products and the growth mechanisms of carbon nanomaterials were addressed. The products were characterized by XRD, SEM, TEM, RAMAN, FTIR and VSM.The results show that coal gas is an appropriate carbon feedstock of which the main components CH4 and CO directly get involved in the formation and growth of carbon nanostructures as the precursors of active building units, while those non-carbon gases H₂ and N₂ play a role in reducing the deactivation of the catalysts in the formation process. The results show that carbon nanostructures with different morphologies were controllably produced by changing the catalysts and the experimental conditions of CVD process.