Production of Carbon Nanotubes from Polyethylene Pyrolysis Gas and Effect of Temperature

Carbon nanotubes (CNTs) were produced by catalytic chemical vapor deposition using, as carbon source, a mixture of hydrocarbons and hydrogen that simulates the effluent gases from pyrolysis of polyethylene (PE). An Fe/Al 3 O 3 catalyst was used in a range of temperatures from 600 to 800 °C. Multiwall carbon nanotubes of 20 nm in diameter and length on the order of micrometers were obtained. Higher yields were observed at 650 °C, where no prior catalyst reduction was necessary. Transmission electron microscopy, X-ray diffraction, and Raman spectrometry show a higher crystalline quality at 750 °C, although the balance yield–quality indicates that 650 °C is a satisfactory temperature for producing CNTs at a reasonable cost, since no extra hydrogen is necessary for the process. In addition to this, the effluent gas from the process can be further used for energy production.