Pore structure and gasification activity of coal and coke studied by small-angle X-ray scattering

ABSTRACT

Carbonisation is one of the important methods to improve the utilisation of coal. The structural composition of coal plays an important role in coal carbonisation. This work used small-angle X-ray scattering (SAXS) to investigate the pore structure of three kinds of raw coals with different carbon content derived from Xingtai City, Hebei Province, China. The structures of the corresponding cokes obtained through carbonisation at 1200°C were investigated by elemental analysis and SAXS. In addition, the gasification reaction of the three cokes (C1, C2, C3) with CO₂ were studied by thermogravimetric analysis. The SAXS results indicate that the surface fractal dimension increases while the pore size decreases, and the pore distribution became wider after carbonisation. In addition, all coals and cokes present a positive deviation from Porod’s law, indicating that there is a micro-fluctuation of electron density in the samples. Besides, it exhibites a negative correlation has been found between the degree of deviation from Porod’s law and the carbon content. The gasification reactivity of cokes C1 and C3 in CO₂ are higher than that of C2, indicating that the pore structures affect the gas reactivity of the three different metamorphic degree cokes in CO₂.

KEYWORDS:

• Coal
• carbonisation
• pore structure
• small-angle X-ray scattering
• synchrotron radiation

Acknowledgements

The authors would like to thank the 1W2A station at Beijing Synchrotron Radiation Facility (BSRF) for supplying the SAXS measurement facilities. We thank Prof Zhihong Li (Institute of High Energy Physics, Chinese Academy of Sciences) for providing the S software.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was funded and supported by Hebei Carbon-based Materials and Application Technology Innovation Center [grant number SG2021149].