Study on structure and combustion performance of Daliuta coal pyrolysis char by Raman spectroscopy

In this study, the structure and combustion performance of pyrolysis chars from Daliuta raw coal, vitrinite-rich sample, inertinite-rich sample and demineralized coal sample were studied by Raman spectroscopy. The results showed that under the same pyrolysis conditions, compared with the pyrolysis char from Daliuta raw coal sample, the pyrolysis char from the demineralized coal sample has more large aromatic ring systems (≥ 6 rings), higher ignition temperature and much low combustion performance. The combustion performance of pyrolysis char from inertinite-rich sample is lower than that from vitrinite-rich sample, and the burnout capacity of pyrolysis char from inertinite-rich sample is far lower than that from vitrinite-rich sample. The ignition temperature (t_i), the combustion reactivity index (t_index) and the wavenumber of D band (W_D) in the Raman spectrum of Daliuta coal char has a good correlation; the correlation coefficients R² obtained by the quadratic curve fitting are 0.9159 and 0.7133, respectively. There is no obvious correlation between burn-out temperature and W_D of Daliuta coal char, indicating that the carbon structure of Daliuta coal char has a significant impact on the ignition temperature and combustion reactivity index of the char, but is no regular effect on the burn-out ability of the char.