Pyrolysis characteristics of low‐rank coals based on double‐gaussian distributed activation energy model

Abstract

Pyrolysis is an important technology in the utilization of low‐rank coals (LRCs) and is a prerequisite stage for other conversion methods. This study aimed to develop an understanding of the pyrolysis process of LRCs, especially the relationship between the pyrolysis kinetics and the internal chemical structure. The chemical structure parameters of all of the samples were obtained using the Fourier transform infrared spectroscopy (FTIR) method. Thermogravimetric (TG) experiments were conducted at different heating rates (5, 10, and 20 K/min), and the experimental results were fitted using the distributed activation energy model (DAEM). DAEM based on double‐Gaussian distribution (2G‐DAEM) exhibited an acceptable fit to the experimental data in this study. An analysis of the chemical structure parameters of the four types of coals and the kinetic model obtained by fitting indicated that the difference in the chemical structure parameters among the coal samples could effectively explain the difference in the pyrolysis process and the activation energy distribution. The primary pyrolysis stage of the coal samples, including the thermal hysteresis effect caused by the increase in the heating rate, was accurately described by the 2G‐DAEM in this study.