Theoretical insight into the enhanced CH4 desorption via H2O adsorption on different rank coal surfaces

• Published in: Journal of energy chemistry Vol. 25; no. 4; pp. 677 - 682
• Main Authors: Zhou, Yanan, Sun, Wenjing, Chu, Wei, Liu, Xiaoqiang, Jing, Fangli, Xue, Ying
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2016
• Subjects: Adsorption; Coal rank; Density functional calculations; ECBM; Methane; Methane; ECBM; Density functional calculations; Adsorption; Coal rank
• ISSN: 2095-4956
• DOI: 10.1016/j.jechem.2016.04.011

The density functional theory was used to investigate the adsorption of CH4 and H2O on different rank coal surfaces.The coal rank is the dominant factor in affecting the adsorption capacity of coal.In order to better understand gas and water interaction with coal of different maturity,we developed fourteen coal models to represent the different rank coal.The interactions of CH4 and H2O with coal surfaces were studied and characterized by their adsorption energies,Mulliken charges and electrostatic potential surfaces.The results revealed that the interaction between coal and CH4 was weak physical adsorption,and that the interaction between coal and H2 O consisted of physical and chemical adsorption.Adsorption energy of coal–H2O system was larger than that of coal–CH4 on all rank coals,suggesting that the adsorption priority in the coal models is H2 O > CH4.Consequently,the injection of H2 O into the different rank coal could effectively enhance the coal bed methane（CBM） recovery.