LIU Shiqi, WANG Tian, DU Yi, FANG Huihuang, WANG He. The effects of supercritical CO2 on the chemical structure of bituminous coal and anthracite[J]. COAL GEOLOGY & EXPLORATION, 2018, 46(5): 19-25. DOI: 10.3969/j.issn.1001-1986.2018.05.003
Citation: LIU Shiqi, WANG Tian, DU Yi, FANG Huihuang, WANG He. The effects of supercritical CO2 on the chemical structure of bituminous coal and anthracite[J]. COAL GEOLOGY & EXPLORATION, 2018, 46(5): 19-25. DOI: 10.3969/j.issn.1001-1986.2018.05.003

The effects of supercritical CO2 on the chemical structure of bituminous coal and anthracite

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National Natural Science Foundation of China(41402135, 41330638, 41727801)

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  • Received Date: May 12, 2018
  • Published Date: October 24, 2018
  • The effects of supercritical CO2(ScCO2)on coal chemical structure play a critical role in CO2 storage capacity in coal. In this study, CO2 sequestration processes were replicated using a ScCO2 geochemical reactor. Four coal samples with different ranks were exposed to ScCO2 and water under 62.5℃ and 15 MPa. Fourier transform infrared spectroscopy and X-ray diffraction analysis were used to identify the chemical structure of the coal samples before and after ScCO2-H2O treatment. Then evolution mechanism of coal chemical structure was studied. The results show that after ScCO2 treatment, the length of aliphatic hydrocarbon generally increased, and only the abundance of the aromatic hydrocarbon in the fat coal increased. The increase of the abundance of the oxygen-containing groups in coal samples was mainly contributed by the increase of hydrogen bonding groups, except for the anthracite whose abundance of the oxygen-containing groups was affected by the dissolution of low-molecular compounds. Swelling caused by ScCO2 caused breakage of cross links between the aromatic layers in fat and lean coal, making the structure of crystallite loose. While the formation of CAr-CAr cross links in the aromatic layer increased the aromaticity and aromatic ring condensation of the fat and lean coal. The falling off of none polycyclic aromatic hydrocarbons in meagre coal and anthracite made the structure of crystallite more compact, and the increase of the length of the aliphatic hydrocarbon reduced the aromaticity and aromatic ring condensation of meagre coal and anthracite.
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