(503d) Production of MWCNT by a FBCCVD (Fluidized Bed Catalyzed Chemical Vapor Deposition) Process

Among the different techniques that have been applied for the processing of multiwall carbon nanotubes (MWCNT), catalytic chemical vapor deposition (CCVD) in a fluidized bed reactor appears promising in principle due to its relatively low cost, the possibility of its working in a continuous way and the potential high yield production. This technique also assures a good homogeneity of the carbonaceous deposit on the catalyst surface, a good contact between the solid phase (supported catalyst) and the gaseous one (the source of carbon), a good thermal homogeneity into the reactor and it allows a quick mass and heat transfer, avoiding a heat gradient along the bed and a reactant concentration gradient. Multi walled carbon nanotubes have been produced from H2-C2H4 mixtures on Fe-Al2O3 catalyst by a fluidized bed catalytic chemical vapour deposition process. Various parameters such as the temperature, the H2:C2H4 ratio, the amount of metal deposited on the support, the amount of the used catalyst, the reaction time, the typology of catalyst and the reproducibility of the process have been examined. The influence of these parameters on the deposited carbon yield is reported, together with observations of the produced material. The nature of the deposited carbon and the quality of the MWCNT obtained were investigated by SEM, TEM, TG-DTA and XRD analyses. The evolution of the catalyst in time and along the reactor was monitored by SEM and ICP analyses.