Chemistry and kinetics of chemical vapor deposition of pyrocarbon - III - Pyrocarbon deposition from propylene and benzene in the low temperature regime

Pyrocarbon deposition from propylene and benzene was studied at ambient pressure and 1000 degrees C using a vertical hot-wall reactor. Initial partial pressures of the hydrocarbons and residence time were varied; the influence of hydrogen in the feed gas was additionally studied. Gaseous and liquid reaction products were analyzed by on-line gas chromatography. The results are discussed in terms of homogeneous gas-phase and heterogeneous pyrocarbon deposition reactions. Reactions models have been derived and used for simulation of pyrocarbon deposition rates and their inhibition by hydrogen. Pyrocarbon deposition from propylene is shown to be controlled by complex pyrolysis reactions in the gas-phase, whereas benzene forms pyrocarbon directly, i.e. without significant formation of intermediate products in the gas-phase. (C) 1998 Elsevier Science Ltd. All rights reserved.