Thermogravimetric-Mass Spectrometric Study of the Pyrolysis Behavior of Shenmu Macerals Under Hydrogen and Argon

Abstract

The pyrolysis characteristics of macerals separated from Chinese Shenmu coal were systematically investigated using TG-151 pressurized thermobalance coupling with mass spectrometer under 0.1 MPa of Ar and H₂, heating rate of 10°C/min and final temperature of 900°C. The TG/DTG results showed that vitrinite always had a higher volatile matter yield, larger maximum rate of weight loss, lower temperature of the maximum rate of weight loss than inertinite. Inertinite showed high response to the external hydrogen, especially at a higher temperature. The gases evolved during thermogravimetric analysis of macerals were analyzed on-line by mass spectrometer for the relative intensity of H₂O, C₁–C₄, and C₆H₆. An obvious difference in evolution curves could be observed. The content of all gases evolved from vitrinite was higher than those from inertinite in both atmospheres. The amount of H₂O and light hydrocarbons was higher in H₂ than that in Ar, indicating the hydrogenation of oxygen-containing functional groups and free radicals formed during pyrolysis. The evolution curves of H₂O and CH₄ had different peak distributions and evolution temperatures under H₂ and Ar, suggesting the different reaction mechanism during pyrolysis in different atmosphere. The evolution curves also revealed the different structural characteristics among vitrinite, inertinite and the parent coal.

Keywords:

• Ar
• evolved gases
• H₂
• macerals
• pyrolysis
• TG-MS

Acknowledgments

This work was supported by the National Basic Research Program of China (No. fj 2004CB217704-3). The authors would also like to thank Prof. Wenhua Li and Dr. Xiangfei Bai for providing the samples.

Notes

^a By difference.