Dynamic Study of Gas-Phase Species during Single-Walled Carbon Nanotubes Production by Chemical Vapor Deposition of Ethanol

The gas-phase species of the reactions that take place during Carbon Nanotubes (CNTs) production by Chemical Vapor Deposition (CVD) of ethanol vapors has been investigated in the temperature range of 650 - 900 degrees C. More specifically, the effluent gases were analyzed by mass spectrometry in correlation to time as a way to determine the reactions that occur during the process and their influence on the rate of carbon deposition, total yield and kind of CNTs produced. The experiments were carried out in a thermogravimetric CVD hot-wall reactor over a Fe2O3/Al2O3 catalyst and the final product was characterized with Scanning Electron Microscopy (SEM) and Raman spectroscopy. It was found that the optimal temperature towards the highest yield of Single-Walled Carbon Nanotubes (SWCNTs) was achieved at 800 degrees C leading to SWCNTs of 0.8 to 1.0 nm diameter. It was also determined that the presence of catalyst is crucial not only for the formation of CNTs, but also for the decomposition of ethanol vapors.