(603g) Effect of H2 Reduction and Ferrocene Role in the Production Lengthy CNT Bundles

Organometallocene catalysts such as ferrocene and nickeloceneare are promising catalysts in the production of free templet CNTs, which is a pre-step in scaling up CVD reactors for large scale production. The catalyst selection, not only controls the CNTs production yields, it highly effects the aspect ratio and surface properties of the produced CNTs. In this study a ferrocene ((C₅H₅)₂Fe) catalyst and P- Xylene hydrocarbon source are atomized in a large lab scale CVD reactor to produce long MWCNTs. H₂ is used with the mixture to reduce the catalyst and was feed to the reactor with Ar. An optimized temperature of 800 ^oC and a H₂ ratio of 4 resulted in high production yields of MWCNTs reaching lengths of 400 nm with high purity as proven by TGA experiments. Although, higher lengths of the produced MWCNTs are recorded by SEM and TEM images, when pure H₂ is used, production yields are lowered because of carbon methanation side reactions . TEM images suggested that the tubes followed a tip growth mechanism over the ferrocene catalyst nanoparticles. Furthermore, the ferrocene imbedded nanoparticles provided structural support during the growth of the MWCNTs which made them grow to high lengthy bundles as shown by SEM images. The atomization of the ferrocene and p-xylene feed solution to the CVD reactor resulted in an umbrella-shaped feed profile which is evenly dispersed inside the reactor. This profile led to more sized controlled ferrocene nanoparticles, and hence, a narrow dimeter distribution of the produced CNTs as suggested by SEM images.