Thermochemical kinetics of anthracene pyrolysis

Abstract

A theoretical analysis of chemical reactions in the early stages of anthracene pyrolysis is presented. This analysis makes extensive use of thermochemical and kinetic estimation methods as well as fundamental principles of free radical kinetics. The focus is on liquid-phase reactions near 500°C although reactions at higher temperatures and at lower densities are also discussed. Some noteworthy predictions concerning anthracene pyrolysis in the liquid phase near 500°C are: 1. (1) Decomposition is initiated by impurities, wall reactions and/or very slow homogeneous reactions. 2. (2) Products are expected to catalyze the reaction once a small amount of decomposition has taken place. 3. (3) Anthracene polymerization involves a step in which a resonance stabilized π-radical adds to the 9-position of an anthracene moiety. 4. (4) The first major molecular product is 9-(9'-anthryl)-9,10-dihydroanthracene. 5. (5) Radicals are generated primarily by molecular disproportionation reactions between 9,10-dihydroanthryl and anthryl structures. 6. (6) Hydrogen atoms released during C-C bond formation are held primarily in 9,10-dihydroanthryl structures. 7. (7) Phenyl-type radicals and free H atoms are not important intermediates at 500°C, although they are probably important in reactions at higher temperatures and in the gas phase.