SOLID-STATE PYROLYSES .4. KINETIC EVALUATION OF COAL PYROLYSES - EFFECTS OF MATURATION

The applicability of pyrolysis-FID to isothermal solid state kinetic studies of coals is discussed, based on investigations of a series of artificially matured coal samples. The kinetic evaluation of the pyrolytic reactions is based on the assumption that the overall reaction can be described by nth order kinetics, where n may not be an integer. The significance of the activation parameters obtained, including the activation entropy, is related to the overall reactions, i.e. the overall activation energies and Arrhenius factors are composite values for the overall mechanism, and not values for single reactions. Hence, the E(a)/ln k(infinity) pairs should be regarded as activation indexes, which should not be confused with the classical kinetic terms activation energy and Arrhenius factor. Analogously, activation entropy, i.e. DELTAS(not-equal) values, derived from overall ln k(infinity) values should be regarded as entropy indices, associated with the overall mechanism of the reactions under investigation. The autocorrelation of kinetic parameters in coal pyrolysis reactions is visualized.