Effects of olefins on the thermal decomposition of propane part III. Some remarks on the kinetics of decomposition

Conditions of applicability of quasi-steady-state kinetic treatment have been investigated with respect to the explanation of the decomposition of propane and the influence of ethylene on this. From the measured rate of accumulation of ethane and from the relations between the kinetic equations describing product formation, the rate parameters of the initiation reactions were determined, for which the temperature-dependences and were found. In the decomposition of propane under the examined conditions, the chain length exceeds 500. In response to ethylene the chain length significantly decreases, but even in this case the decomposition chains are long enough for it to be assumed that the ratios of radical concentrations are governed by the propagation steps. Calculations demonstrated that the actual radical concentration during a sufficiently short induction period approximates to the stationary concentration, so that it does not seriously affect the accuracy of the kinetic treatment.