Effects of Supercritical CO 2 Treatment Temperature on Functional Groups and Pore Structure of Coals

Zhaolong Ge, Mengru Zeng, Yugang Cheng, Haoming Wang and Xianfeng Liu
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Zhaolong Ge: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
Mengru Zeng: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
Yugang Cheng: National and Local Joint Engineering Research Center of Shale Gas Exploration and Development, Chongqing Institute of Geology and Mineral Resources, Chongqing 400042, China
Haoming Wang: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
Xianfeng Liu: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China

Sustainability, 2019, vol. 11, issue 24, 1-16

Abstract: The buried depth of a coal seam determines the temperature at which CO 2 and coal interact. To better understand CO 2 sequestration, the pore structure and organic functional groups of coal treated with different ScCO 2 temperatures were studied. In this study, three different rank coals were treated with ScCO 2 at different temperatures under 8 MPa for 96 h in a geochemical reactor. The changes in pore structure and chemical structure of coal after ScCO 2 treatment were analyzed using mercury intrusion porosimetry, attenuated total reflection Fourier transform infra-red spectroscopy, fractal theory, and curve fitting. The results show that the enhancement effect of ScCO 2 on pore structure of coal becomes less significant as the increase of buried depth. In most of the treated coal samples, the variation proportion of mesopores decreased and the variation proportion of macropores increased. In the relatively higher rank coals, the degree of condensation (DOC) of aromatic rings decreased after treatment with ScCO 2 . The DOC values showed a U-shape relationship with temperature, and the aromaticity showed a downward trend with increasing temperature. The chemical structural changes in the relatively lower rank coal sample were complex. These findings will provide an understanding of mechanisms relevant to CO 2 sequestration with enhanced coalbed methane recovery under different geothermal gradients and for different ranks of coal.

Keywords: FTIR spectroscopy; pore structure; supercritical carbon dioxide; geological sequestration; coal rank (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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