Kinetic study of single-walled carbon nanotube synthesis by thermocatalytic decomposition of methane using floating catalyst chemical vapour deposition

Abstract

Single walled carbon nanotubes (SWCNTs) have been synthesized from thermocatalytic decomposition of methane by using ferrocene as the catalyst at atmospheric pressure. Floating catalyst chemical vapour deposition using a horizontal two zone reactor was employed to investigate the kinetics. The effects of temperature of synthesis (800–1000 °C), partial pressure (2–40 kPa) of reactant gas and catalyst concentration (0.2–4.6 mol m−3) on the rate of formation of SWCNTs have been studied. The rate is proportional to the partial pressure of methane indicating that the surface reaction of methane on the active site is the rate controlling step. The activation energy was found to be 80.16 kJ mol−1. Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, BET, UV–Vis-NIR and thermogravimetry have been used for the characterization of products. UV–Vis-NIR spectroscopy data reveals presence of 78–82% metallic SWCNTs (m-SWCNTs) in the synthesized samples. The BET surface area of purified SWCNTs were found to be 871 m2 g−1 with pore volume of 0.35 cc g−1 and electrical conductivity of 856–746 S cm−1.