Pyrolysis mechanism of carbon matrix precursor cyclohexane(IV)-formation process of intermediates C 4H X ( X=3,4,5)

Abstract

Formation mechanism of important intermediate C 4H X ( X=3,4,5) of the pyrolysis process of carbon matrix precursor cyclohexane was studied theoretically. Thermodynamic and kinetic parameters of the possible reaction paths that start with C 2H 3 and C 2H 2 were computed by UB3LYP/6-31+G ∗ at different temperatures. The results show that: (1) the condensation processes of C 2 species are all spontaneous, but higher temperature ranges takes disadvantages for the processes; (2) from the viewpoint of thermodynamics, major reaction path is to form C 4H 5 first and further produce other C 4 species by dehydrogenating reactions; (3) the major reaction path supported by thermodynamics is also feasible from the viewpoint of kinetics and the activation energy of the rate-determining step of the path is 143.13 kJ/mol; (4) At all temperatures, the major reaction path has not been changed.