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 ambien t pressure and 1000 degrees C using a vertical hot-wall reactor. Initi al partial pressures of the hydrocarbons and residence time were varie d; the influence of hydrogen in the feed gas was additionally studied. Gaseous and liquid reaction products were analyzed by on-line gas chr omatography. The results are discussed in terms of homogeneous gas-pha se and heterogeneous pyrocarbon deposition reactions. Reactions models have been derived and used for simulation of pyrocarbon deposition ra tes and their inhibition by hydrogen. Pyrocarbon deposition from propy lene is shown to be controlled by complex pyrolysis reactions in the g as-phase, whereas benzene forms pyrocarbon directly, i.e. without sign ificant formation of intermediate products in the gas-phase. (C) 1998 Elsevier Science Ltd. All rights reserved.