The dependence of catalytic carbon filament growth kinetics upon gas phase carbon activity

✍ Scribed by S.A. Safvi; E.C. Bianchini; C.R.F. Lund

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 615 KB
• Volume: 29
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(91)90043-i

✦ Synopsis

Previous studies using an a-iron catalyst showed that the rate of carbon filament growth was linearly proportional to the gas-phase carbon activity (ac) at lower u,. At higher a, the rate then became nearly independent of the gas-phase carbon activity. It was also reported that y-iron did not show two regions of linear behavior, but instead a smooth transition from low a, where the rate was strongly dependent, to high ac where it was nearly independent. In the present study, nickel has been observed to behave in a manner similar to that of y-iron. A model is presented which explains this behavior, The model includes the effect of concentration upon the diffusivity of carbon in the metal. It predicts qualitatively the observed dependence of rate upon gas-phase carbon activity.