Online characterization of pyrolysis products and kinetics study for the pyrolysis of a coal

The compositional distribution of pyrolysis products is related to the molecular structure of coal and pyrolysis parameters. In this study, gaseous products generated from the pyrolysis of two low-rank coals were analyzed by an online home-built infrared detection system. The effect of heating rate and temperature on compositional distribution was considered and evaluated. Fourier transform infrared (FTIR), gas chromatograph/mass spectrometry (GC/MS), and Orbitrap-MS were employed to analyze other pyrolysis products such as raw coals, chars, and tars. In the pyrolysis process, oxygen-containing compounds in coal were the first species to participate in pyrolysis reactions. With the enhancement of temperature, the content of aromatic hydrocarbons showed an increasing trend, and the contents of aliphatic hydrocarbons and oxygenates decreased. In the four major pyrolysis gases, the yield of H-2 was the highest and the lowest for CO2. In addition, dynamic curves of the main pyrolysis gas were obtained, and the activation energies of pyrolysis gases were calculated by Ozawa-FlynnWall's (OFW) method. The possible generation pathways of gaseous products were proposed.