Pyrolysis kinetics and reaction mechanisms of coal slime for cleaner energy.

Pyrolysis has been demonstrated to be promising for the conversion of coal slime (CS) to fuels and high value-added chemicals, which could achieve resource utilization of CS. For the in-depth understanding of the pyrolysis mechanism of CS, in this study, the pyrolysis kinetics and pyrolytic products distribution were investigated by TG-FTIR and Py-GC/MS and compared with those of raw coal (RC). The results demonstrated that the pyrolysis of CS comprises three reaction stages, with the decomposition of volatiles as the main stage (180–680 °C). Using the master plot method, the pyrolysis kinetic mechanism of RC and CS were predicted to be f(α) = (1 – α)4.6 and f(α) = (1 – α)5.4, respectively. The enrichment of inorganic minerals significantly increased the order of the CS pyrolysis reaction, indicating that minerals play an important role in the pyrolysis chemical reaction. Compared to that of RC, the alkene content of CS pyrolysis products decreased significantly, while the contents of CO 2 and aromatics increased, indicating that the minerals in CS promote the polymerization and cyclization of alkene, as well as the formation of macrocyclic aromatic hydrocarbons in CS tar. Those consequences also determined that inorganic matter in CS considerably affects pyrolysis, which in turn affects the whole pyrolysis process and tar quality. Therefore, in this study, theoretical and practical guidance on the efficient thermochemical conversion and utilization of CS is provided. • RC and CS were comparatively pyrolized. • Minerals in ash enhance kinetics resulting in higher reaction order. • CS rich in AAEMs promoted the formation of phenol and alcohol. • Tar precursors prefer to form larger PAHs by high ash content from CS. [ABSTRACT FROM AUTHOR]