Chemical structure and pyrolysis characteristics of demineralized Zhundong Coal

ABSTRACT

To investigate the effects of acid treatments on the chemical structure and pyrolysis behavior of coal, we examined the low-rank Zhundong coal pretreated by four single acids (HCl, HF, H₂SO₄, HNO₃) and a combined acid (HCl-HF-HCl). Our results indicated that the carboxylic and phenolic hydroxyl contents of the coal increased, while the aliphatic and aromatic hydrogen contents decreased after leaching. Nitric acid destroyed long aliphatic chains in coal, which caused the key pyrolysis stage to occur at lower temperature, the number of volatiles increased, and the pyrolysis rate improved.

KEYWORDS:

• Chemical structure
• demineralization
• FTIR
• pyrolysis
• Zhundong coal

Funding

The authors wish to thank the National Natural Science Foundation of China (Grant No. 51376053 and No. 51536002) for the financial support of this work.