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Effect of the carbon source on the synthesis of carbon nanotube by catalytic chemical vapor deposition

Abstract:

In catalytic chemical vapor deposition method (CCVD), CNTs growth is mainly affected by the physicochemical characteristics of the catalyst and the type of carbon source. In this work, CNTs were obtained from a FeMo/MgO catalyst, prepared by the nitrate-citrate sol-gel method, using CCVD with different carbon sources (methanol, ethanol and p-xylene) at 900 °C for 90 min. Catalyst and products obtained during the pyrolysis reaction were analyzed by X-ray diffraction and electron and atomic force microscopes. Carbonaceous products were obtained from methane with a yield of 28.4 wt % (based on initial weight of catalyst) and the highest quantity of amorphous carbon, increasing this yield to 49.9 wt % when ethanol was used. However, p-xylene was found to be the best carbon source due a yield of 243.0 wt %. These results indicate that, while keeping constant the type of catalyst, temperature and pyrolysis time, the increase of the number of carbon atoms and aromaticity in the precursor favors the growth of CNTs. The magnetic properties were measured. A decreased of magnetization after purification treatment was observed. This indicates partial elimination of Fe nanoparticles included in CNTs due to CCVD process. This corroborates the effectivity of the purification process.