Catalytic carbon nanotube and fullerene synthesis under reduced pressure in a batch reactor Original Research Article

Catalytic decomposition of acetylene was studied under reduced pressure in a batch reactor over catalyst samples, which previously showed outstanding activity and selectivity in carbon nanotube formation in a fixed-bed flow reactor under atmospheric pressure. It was found that activity depends on the nature of the catalyst sample at lower acetylene pressure. Characterization of the samples was carried out by transmission electron microscopy and X-ray diffraction. Concerning the quality and the graphitization of carbon nanotubes, selectivity showed a strong dependence on the initial pressure. With decreasing pressure the formation of fullerenes was obtained. To detect the amount of fullerenes and polyaromatic hydrocarbons, Soxhlet extraction followed by high pressure liquid chromatography (HPLC) mass spectrometry (MS) analysis was carried out. Certain catalyst samples showed activity in fullerene formation independent of pressure. HPLC results support a mechanism for catalytic C60 formation via polyaromatic hydrocarbons as building blocks.