Pyrolysis behaviors and product distribution of Shenmu coal at high heating rate: A study using TG-FTIR and Py-GC/MS

Abstract

The chemical properties, pyrolysis behaviors and pyrolysis product distributions of Shenmu (SM) coal were investigated by proximate and ultimate analysis, thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR) and Pyrolyzer coupled with gas chromatography/mass spectrometry (Py-GC/MS). The results of the proximate and ultimate analysis indicated that SM coal had less saturated aliphatic structures and more polar components. The coke yield for SM coal during pyrolysis process at 100 °C/min, 300 °C/min, and 500 °C/min was 65.60%, 64.19%, and 63.15%, respectively, which indicating that the increment in heating rates could promote the production of volatile substances. Moreover, there was a lateral shift to high temperature of TG/DTG curves when the heating rates increasing. The main volatile species detected from FTIR in the pyrolysis of SM coal were CO2, CO, CH4, C2H4, C2+ aliphatics, light arenes, CO bond containing species and CO bond containing species. Since the difference in the temperature intervals of those volatile species released, the sources of cleavage or chain scission during pyrolysis process were not the same. According to the fast pyrolysis by Py GC/MS, the volatile species could be divided into eleven species including alkenes, cycloalkenes, alkanes, cycloalkanes, aromatics, phenols, ethers, ketones, alcohols, N-containing species, and other species. The relative contents of alkenes and alkanes were dominant regardless of the variegation of heating rate, residence time and pyrolysis final temperature. Furthermore, the trend of each species under different influence factor conditions achieved different tunes rendered with equal skill.