Modelling study of single walled carbon nanotube formation in a premixed flame

Abstract

In this study the formation processes of catalyst nanoparticles and single walled carbon nanotubes (SWCNTs) in a premixed flame doped with Fe(CO)₅ were first modelled using a three-step SWCNT growth model including a detailed surface chemistry model. The growth of SWCNTs was experimentally studied by the length measurement of the SWCNT using Raman radial breathing mode (RBM) and size measurements of the iron oxide catalyst particles using XRD and TEM. The flame chemistry and the formation of the catalyst particles were modelled in detail by means of a sectional model. In a post-processing step the SWCNT population balance growth model was numerically solved using a multivariate stochastic population balance solver. The model was able to capture the growth characteristics and revealed the role of the monolayer. The computational study on the adsorption, dissociation, and reactions of CO, H₂ and H₂O on iron nanoparticles showed that carbon, hydrogen and oxygen atoms form at the surface of the catalyst. Their ratio, which is controlled by the surface reaction pathways, affects the growth of SWCNTs, the formation of monolayers and the phase transformation of catalyst particles.