Scaled-up production of multi-walled carbon nanotubes using catalytic chemical vapour deposition

The widely employed catalytic chemical vapour deposition (CCVD) process which uses the xylene/ferrocene precursor solution has been scaled-up to a reactor volume of 16 L to produce large quantities of multi-walled carbon nanotubes (MWNTs). The purpose of scaling up the CCVD process was to establish parameters for successful production of high purity MWNTs and develop procedures to coat large substrate areas for later incorporation in polymeric matrices. Generally, it was found that temperatures, precursor solution concentrations and carrier gas ratios, previously reported on a research scale, provided suitable conditions for larger scale production. Mass flow rates of carrier gases were, however, substantially lower than rates used in low volume reactors. Characterisation of the MWNTs using scanning and transmission microscopy (SEM, TEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) indicated MWNTs approximately 55nm in diameter and over 55mum in length, and contained small quantities of iron oxide, when produced over a 2 hour period. Initial experiments also indicated that planar growth of MWNTs was possible between the strands of quartz fibre matting.