An Updated Review of Synthesis Parameters and Growth Mechanisms for Carbon Nanotubes in Fluidized Beds

Research published since 2006 on the synthesis of carbon nanotubes (CNTs) using chemical vapor deposition (CVD) in a fluidized bed reactor is reviewed A complete account of experimental procedures, including upstream treatments (catalyst preparation, calcination, and reduction), synthesis conditions, and downstream processes (purification) is presented in an attempt to determine the effect of these variables on carbon nanotube morphology, diameter, yield, and quality The formation and growth mechanisms of carbon nanotubes by CVD is reviewed in detail in an attempt to account for discrepancies in the properties of CNTs produced from experiments at superficially similar conch tons This reveals that the underlying variables that appear to control growth are not directly manipulated in the CVD process, rather they are determined by complex interactions between variables Thus, the current change-one-factor-at-a-time experimental paradigm, which assumes orthogonal variables, is the most likely source of the conflicting experimental results reported in the literature, and does not give insight into CNT growth or permit global process optimization.