Ab initio study on elementary radical reactions in coke formation

Ab initio calculations are presented on radical reactions that occur during the formation of coke in a thermal cracking unit. Kinetic parameters for the addition reaction of the ethylbenzene radical to ethene and the subsequent cyclization of the butylbenzene radical are calculated by means of Transition State Theory and Density Functional Theory. Special care is taken to correctly treat the internal rotations to predict accurate values of the preexponential factor. The influence of the local structure of the coke matrix on the kinetic parameters is tested by calculating kinetic parameters of clusters consisting of more than one benzene ring.