Structural evolution around first coalification jump revealed by TG/MS and FTIR

ABSTRACT

Structural features from Fourier transform infrared spectroscopy and evolution characteristics of the main pyrolysis products by TG/MS were studied for seven coals ranging from lignite to high-volatile bituminous A coal. It showed that the chemical structure presents a sudden change at ~0.6% of R^O_max, corresponding to the first coalification jump. The results suggested that the C=O content was the lowest and thus CO₂ generation during pyrolysis has the lowest ion intensity at ~0.6% of R^O_max, while the aliphatic hydrocarbons have the maximum intensity at ~0.6% of R^O_max. Besides, the peak temperatures of CH₄⁺, C₃H₇⁺, and benzene released during pyrolysis present the approximate minimum values near 0.6% of R^O_max, demonstrating the lowest thermal stability of coal near 0.6% of R^O_max. This study provides a deep understanding of the first coalification jump.

KEYWORDS:

• Abrupt change
• first coalification jump
• FTIR
• structural evolution
• TG/MS

Funding

The authors gratefully acknowledge the financial supports of the National Science Foundation of China (Grant Nos. 41302127, 41372165, 41572144, 41402137), Natural Science Foundation of Shanxi Province in China (Grant No. 2015021165), the China Scholarship Council (File No. 201508140054), and Shanxi Provincial Coal Basis Key Scientific and Technological Project (Grant No. MQ2014-01).

Additional information

Funding

The authors gratefully acknowledge the financial supports of the National Science Foundation of China (Grant Nos. 41302127, 41372165, 41572144, 41402137), Natural Science Foundation of Shanxi Province in China (Grant No. 2015021165), the China Scholarship Council (File No. 201508140054), and Shanxi Provincial Coal Basis Key Scientific and Technological Project (Grant No. MQ2014-01).