KINETIC MODELING OF THE THERMAL-CRACKING OF HYDROCARBONS .1. CALCULATION OF FREQUENCY FACTORS

The kinetic modeling of the thermal cracking of hydrocarbons is done by means of a free-radical reaction scheme containing several hundreds of reactions. The most important problem to be solved is to assign values to the corresponding reaction rate parameters. The procedure used for the frequency factors is dealt with. Starting from detailed mechanisms for every reaction, a structure is set forward for the corresponding activated complex. The standard entropy of the activated complex is estimated by means of statistical thermodynamics. The frequency factor is then calculated by means of the results of transition-state theory. The procedure drastically reduces the number of parameters. These are now related to the fundamental aspects of transition-state theory.