Study on the source of polycyclic aromatic hydrocarbons (PAHs) during coal pyrolysis by PY-GC-MS

Hazardous organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) generated during the course of coal pyrolysis are highly mutagenic and carcinogenic. The relation between the amount of PAHs from the raw coal and that generated from coal pyrolysis were studied. Firstly, three Chinese coals from Huolinhe, Ximeng and Fenxi were respectively extracted by dichloromethane, and then, online pyrolysis analysis of the raw coals, their extraction residues and extracts were carried out respectively by PY (Pyro-probe CDS 5250)-GC-MS. The experimental results showed that the PAHs generated from the Huolinhe, Ximeng and Fenxi coals in the course of their pyrolysis was 523, 327 and 1707 μg/g, respectively, which were much higher than the free PAHs extracted from their corresponding raw coals. The PAHs in the raw coals were dominated by 4,5-ring PAHs, while those generated from the coal pyrolysis were dominated by lower-ring (2,3-rings) PAHs. A lot of important information about the generation of PAHs from residue pyrolysis was also included in the paper which indicated that the PAHs were mainly from complex chemical reactions of the coal pyrolysis, and PAHs were more likely to be generated from the residue pyrolysis due to the increased pores that appeared on the coal surface during the course of extraction operation.