Large scale production of multi-walled carbon nanotubes by fluidized bed catalytic chemical vapor deposition : a parametric study

摘要

A parametric study investigating the impact of temperature, run duration, total pressure, andudcomposition of the gaseous phase on the catalytic growth of multi-walled carbon nanotubesud(MWNT) has been performed. MWNT have been produced very selectively on the multiudgram scale by catalytic chemical vapor deposition from ethylene in a fluidized bed reactor.udThe kinetics of MWNT growth is fast and, with the catalyst used, no induction period hasudbeen observed. The kinetic law is positive order in ethylene concentration and the process isudlimited by internal diffusion in the porosity of the catalyst. The formation of MWNT in theudmacroporosity of the catalyst induces an explosion of the catalyst grains. Such a process, thanks to the absence of temperature gradient and to the efficient mixing of the grains allows a uniform and selective treatment of the catalyst powder leading to very high selectivityudtowards MWNT formation. High purity MWNT have been obtained after catalyst dissolution.udDepending on the temperature of production, the specific surface area of this material rangedudbetween 95 and 455 m2/g.