Study of Pyrolyzates from a Variety of Indian Coals and Their Dependency on Coal Type and Intrinsic Properties – An Analytical Fast Pyrolysis Study

ABSTRACT

Pyrolysis is a promising technique used to produce oil, syngas, and char of high utility. This work investigates the pyrolytic products and char yields of nine different Indian coals collected from various coal subsidiaries through analytical fast pyrolysis. Coal pyrolysis was performed at 750°C with a single-shot micro pyrolyzer interfaced with gas chromatograph mass spectrometer (GCMS). The characteristics of coal samples were studied and the mean higher heating value (HHV) of coals was determined as 26.26 ± 1.81 MJ/kg. The main pyrolyzates in coals in terms of area composition percentage are identified as C₀- to C₃-alkylbenzenes (13.83 ± 3.76%), C₀- to C₃-alkylphenols (12.843 ± 8.18%), C₀- to C₃-alkylnaphthalene (6.378 ± 3.491%), C₀- to C₃-alkylindenes (0.98 ± 0.301%), and alkylphenanthrenes and alkylanthracenes (1.054 ± 1.655%). Among all the pyrolyzates, alkyl phenol was found to be most widely distributed in the coal samples. The pyrolytic product dependency on various intrinsic properties of coal was analyzed. A second order correlation equation between the coal type number and main pyrolyzates was established that fitted well (R² = 0.97) with the obtained data. The char yields from pyrolysis of Indian coals were determined in the range 58.07–80.55% with a mean value of 70.00 ± 6.29%. The carbon contents of the chars were found to be higher than the original coals and the mean HHV of chars was estimated to be 24.47 ± 2.26 MJ/kg. Overall, this study gave an insight into the coal pyrolyzates produced from a variety of Indian coals and their interrelations with the intrinsic coal properties. The results of this study can serve as a reference material for furthering research on coal pyrolysis and establishing relations between the coal properties and pyrolytic products generation.

KEYWORDS:

• Indian coal
• coal intrinsic properties
• analytical fast pyrolysis
• pyrolytic products
• coal type number
• char yield

Acknowledgments

The authors gratefully acknowledge the financial support received from the Science & Engineering Research Board (SERB), Govt. of India for this study (Grant No. EMR/2016/004210). The authors are also thankful to all the coal companies for providing the coal samples. Authors also express their sincere thanks to NCCRD, IIT Madras for extending the experimental facilities for the study. Deepest gratitude also goes to Dr. R. Vinu, Department of Chemical Engineering, IIT Madras for his valuable suggestions and guidance in conducting the experiments.

Declaration of competing interest

The authors declare no conflict of interest.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by the Science and Engineering Research Board [EMR/2016/004210].