Pyrolysis behavior and product distribution of exinite submacerals

Abstract

This paper systematically investigated the pyrolysis behavior and product distributions of exinite submacerals isolated from different low-rank coal using thermogravimetric analyzer coupled with Fourier Transform infrared spectroscopy (TG-FTIR) and Pyrolyzer coupled with gas chromatography/mass spectrometry (Py-GC/MS). The functional groups in exinite submacerals were studied by FTIR simultaneously. Results suggested that all submacerals were less aromatic with abundant aliphatic chains and more oxygen-containing functional groups. Besides, the TG profiles lateral shifted towards higher temperatures with the heating rates. The kinetic parameters (E and A) indicated that the calculated activation energy and frequency factor of the resinite were the largest, and the barkinite was close to cutinite, while the sporinite was the smallest. The release of CO2, CH4, H2O and CO were measured during pyrolysis process. The temperature intervals and contents for these volatile species reflected the difference in pyrolysis mechanism and the contents of functional groups for different submaceral. According to the fast pyrolysis (650 ℃) by Py-GC/MS, the volatile species could be classified into eight categories including alkanes, alkenes, cycloalkanes, arenes, alcohols, phenols, heteroatomic compounds and ketones. The pyrolysis behavior and product distributions of submacerals were closely related to the chemical structure of its special parent material. The sensitivity of different chemical structures in exinite submacerals to temperature achieved different trends of pyrolysis behavior and product distribution.