The mechanism of action of heterogeneous catalysts in the radical-chain processes of hydrocarbon pyrolysis

Theoretical concepts and experimental data on the mechanism of catalyst action in the radical-chain process of hydrocarbon pyrolysis are systematized and generalized. We consider the kinetic model involving both heterogeneous and homogeneous components of the process that allows one to predict four types of influence of the surface on the radical-chain process: (1) inhibition, (2) neutral behavior, (3) acceleration of heterogeneous component, and (4) acceleration of the homogeneous component via supply of additional radicals to the volume. Peculiarities of the influence of the catalyst amount and substrate dilution on the rate of the process, which seem unusual from the standpoint of the theory of catalysis, stem from this kinetic model