Pyrolysis Behaviors and Reaction Mechanisms of Coal Slime: A Study Based on TG-FTIR and PY-GC/MS

Abstract

With the increase of washing raw coal, the rapid increase of coal slime (CS) production has become an urgent environmental problem. The main purpose of this work is to investigate the pyrolysis behavior and product distribution of CS by using thermogravimetric analyzer coupled to Fourier transform infrared spectroscopy (TG-FTIR) and Pyrolyzer-gas chromatography/mass spectrometry analysis (Py-GC/MS). The results showed that the pyrolysis of CS can be divided into three stages. The maximum weight loss of CS occurred in the main devolatilization stage at 178-680 oC. The pyrolysis kinetic mechanism of CS was predicted to be f(α)=(1-α)5.4 via the master-plots method. The increase of inorganic minerals significantly increased the order of CS pyrolysis reaction, indicating that minerals have a great influence on pyrolysis chemical reaction. Compared to raw coal, the alkene contents decreased significantly, while the contents of CO2 and aromatics increased significantly, illustrating that the minerals in CS promoted polymerization and cyclization reactions of alkene as well as the formation of macrocyclic aromatic hydrocarbons in CS tar. This study provided theoretical and practical guidance on efficient thermochemical conversion and utilization of CS.