Kinetic parameters estimation and reaction model modification for thermal degradation of Beizao oil shale based on thermogravimetric analysis coupled with deconvolution procedure

Abstract

Pyrolysis characteristics of Beizao oil shale in nitrogen were investigated by thermogravimetric analysis coupled with deconvolution procedure. A new method was proposed to separate multistep thermal decomposition process. Kissinger-Kai method was employed to determine the peak positions of main components involved in the complex reaction, and the overlapping peaks were separated by bi-Gaussian function according to the thermal knowledge of sub-reaction. The results showed that four parallel reactions were observed in the whole process, including the decomposition of kerogen, pyrite, carbonate, as well as removal of crystal water from clay minerals. Furthermore, the kinetic parameters of the separated reactions were estimated by traditional model-free and model-fitting methods on the basis of deconvolution analysis, wherein the optimal reaction models were modified with the accommodation function. Eventually, these parameters were optimized to predict the pyrolysis behavior. It was found that the obtained kinetic parameters and four-component reaction models can well characterize the entire pyrolysis process of Beizao oil shale.