Comparative kinetics of coal and oil shale pyrolysis in a micro fluidized bed reaction analyzer

Abstract

The characteristics and kinetics of coal and oil shale pyrolysis were comparatively studied by using a micro fluidized bed reaction analyzer (MFBRA). The isothermal differential model was first applied to calculate the kinetic parameters of activation energy and frequency factor according to the major gas components during pyrolysis. The results showed that the major gas components released from coal and oil shale under the isothermal condition had different initiating and ending time points, and the difference was more significant under the programmed heating conditions. The shrinking core model allowed better fitting relevance for the coal pyrolysis, while the three-dimension model was more suitable for oil shale pyrolysis, indicating that the gases from the pyrolysis process of coal and oil shale might go through different reaction paths. The activation energy of oil shale pyrolysis was 36.96 kJ·mol−1, larger than the value of pyrolysis of the two coals, which was 21.16 and 32.17 kJ·mol−1, respectively. The above results justified that the oil shale pyrolysis with high ash contents was somehow more difficult to take place in terms of higher activation energy and the MFBRA could be a useful tool to give some insight into the intrinsic kinetics and reaction mechanisms of coal and oil shale pyrolysis.