Structural and pyrolysis behaviors analysis of coal pretreated with a weak acid

ABSTRACT

Mineral matters are essential components of coal and significantly affect its thermal conversion process. To investigate the effects of the minerals on the structures and pyrolysis behaviors, three middle/low-rank Xinjiang coals were mildly pretreated with a weak organic acid with low concentration. We evaluated the physicochemical properties and mineral matters of raw and acid-pretreated coals and analyzed their pyrolysis behaviors. The results indicated that the chemical structure of coals changed slightly; their physical pore structure enlarged; the content of metal cations decreased obviously. The minerals are adverse to conducting the depolymerization and decomposition reaction at the temperature lower than 300 °C. With the temperature increasing, the minerals exhibit excellent catalytic performance and reduce the release of gaseous products (H₂O, CO₂, H₂, C₁~C₃) mainly from the polycondensation and secondary reaction. The coal rank and the content of coal ash could affect the catalytic performance.

KEYWORDS:

• Xinjiang coal
• mineral matters
• coal structures
• pyrolysis behaviors
• TG-MS analysis

Acknowledgments

The authors would like to thank Ms. Xiaojie Cheng and Mr. Hong Huang for their helpful discussion and suggestions.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (21566033 and 21476002) and the NSFC-Xinjiang Joint Fund (U1703253).

Notes on contributors

Ping Zhu

Ping Zhu was born in Anhui Province, China, in 1990. He received his B.S. degree in 2015 from the Anhui University of Technology under the supervision of Prof. Zhiping Lei. Then, he joined Prof. Jianshu Zhang’s lab at Shihezi University and obtained his M.S. degree in 2018 with research on structure and pyrolysis of coal. In the same year, he got a Ph.D. position at the Technical University of Denmark supported by China Scholarship Council and now work on catalysis with renewable from biomass under supervision of Prof. Anders Riisager.

Shumiao Quan

Shumiao Quan was born in Jiangxi Province, China, in 1993. She received her B.S. degree in 2015 from the Anhui University of Technology under the supervision of Prof. Shigang Kang. Then, she joined Prof. Zhenyu Liu’s group to study for M.S. degree at Beijing University of Chemical Technology in 2015 and then continued to study in this team to pursue D.S. degree by the master-doctor combined program in 2017 and now work on biomass pyrolysis.

Zhiping Lei

Zhiping Lei completed an M.S. degree at the Taiyuan University of Technology in 2003 and went on to obtain his Ph.D. degree in 2007 from the Institute of Coal Chemistry, Chinese Academy of Sciences under the supervision of Prof. Zhenyu Liu. In 2008, he was an Associate Professor in the School of Chemistry & Chemical Engineering, Anhui Key Laboratory of Coal Clean Conversion & Utilization, Anhui University of Technology. Then, he obtained the Professor position since 2012.

Jianshu Zhang

Jianshu Zhang received his Ph.D. degree in Chemical Technology from the Institute of Coal Chemistry, Chinese Academy of Sciences in 2010. In the same year, he was introduced to School of Chemistry and Chemical Engineering, Shihezi University. He worked as a Researcher/ Professor at Key Laboratory for Green Process of Chemical Engineering of Xinjiang Bingtuan.