Synthesis of catalyst particles for carbon fiber growth in a vapor-grown carbon-fiber reactor

Carbon fibers have become important in matrix reinforcement, thermal, electrical and magnetic applications. The focus of this study is the synthesis of Vapor Grown Carbon Fibers (VGCF) which are produced by the pyrolysis of hydrocarbons over catalytic transition metal particles. A model had been developed to study the formation of catalyst particles and VGCF growth in a flow reactor. The model includes the three distinct phenomena that take place inside a Vapor Grown Carbon Fiber (VGCF) reactor. The phenomena are--heat transfer to the flowing gaseous reactants, particle formation and growth in the flow, and the carbon fiber growth from the catalyst particles. The model predicts the nucleation rates of particles by determination of collision frequency of catalyst molecules which are produced by gas phase reactions. Calculations had been carried out to determine the growth rates of the catalyst particles in the mixture and of the carbon fibers from the catalyst. Results indicate that submicron catalyst particles are produced in the process; consequently, carbon fibers that are formed are submicron in diameter. The model predictions of the catalyst particle growth compare well with results from an experimental VGCF reactor.