Pyrolysis of the polymer coal: structure and kinetics

A kinetic model which predicts the rate of formation of gaseous products produced during coal pyrolysis was developed. The main assumption is that different coals consist of the same organic functional groups and that the differences between coals are due to the different concentrations of the functional groups. The functional groups most important in forming gaseous products are hydroaromatic hydrogen, methyl groups, ethyl groups and oxygen functionalities. The products of coal pyrolysis are to a large extent determined by the initial concentration of each of the above mentioned functionalities. The limitations of the model are: the model does not predict tar yields; the model is limited to low pressure applications due to neglect of secondary reactions; the rate constants for the release of the free radicals from the coal are applicable to low heating rates; and correlations predicting the initial functional group distribution are limited to coals containing between approximately 70% C and 92% C.