Roles of the Porosity and Surface Oxygen Groups on the Adsorption of Methane on Coals

Abstract:

One bituminous coal was modified with H₂O₂, (NH₄)₂S₂O₈ and HNO₃ respectively, to prepare coal samples with different surface properties. The oxygen groups on coal surface were characterized by X-ray photoelectron spectroscopy (XPS). The textures of the coal samples were investigated by N₂ adsorption at 77 K. The methane adsorption behaviors of the coal samples were measured at 303 K in pressure range of 0-5.3 MPa by a volumetric method. The methane adsorption data were fitted to the Langmuir model. It was observed that there was, in general, a positive correlation between the methane adsorption capacity and the S_BET of coals while a negative correlation between methane saturated adsorption capacity and the O_total/C_total. The methane adsorption capacity was determined by the coal surface chemistry when the microporosity parameters of two samples were similar. Coal with a higher amount of oxygen surface groups, and consequently with a less hydrophobic character, had lower methane adsorption capacity.

• Periodical: Advanced Materials Research (Volumes 781-784)
• Pages: 2415-2419
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.781-784.2415
• Online since: September 2013
• Authors: Shi Xiong Hao, Zu Xiao Yu, Xing Yong Liu
• Keywords: Adsorption, CoAl, Methane, Surface Oxygen Groups

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