Changes in Pore Structure and Fractal Characteristics of Solvents Pretreated High-Rank Coal under Supercritical CO<sub>2</sub>
CO<sub>2</sub> injection in coal seams, which is a significant initiative to mitigate environmental problems caused by greenhouse gases, often leads a sequence of changes in the physical properties of coal reservoirs. To look into how the pore structure changes in the process of CO<su...
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MDPI AG
2024-02-01
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| Series: | Fractal and Fractional |
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| Online Access: | https://www.mdpi.com/2504-3110/8/3/141 |
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| author | Yong Li Xiaodong Zhang Yijuan Sun Zhen Wang Shuo Zhang Binghui Li |
| author_facet | Yong Li Xiaodong Zhang Yijuan Sun Zhen Wang Shuo Zhang Binghui Li |
| author_sort | Yong Li |
| collection | DOAJ |
| description | CO<sub>2</sub> injection in coal seams, which is a significant initiative to mitigate environmental problems caused by greenhouse gases, often leads a sequence of changes in the physical properties of coal reservoirs. To look into how the pore structure changes in the process of CO<sub>2</sub> sequestration, we selected fresh coal from Huoerxinhe coal mine in China as the object. Then, acid treatment and SC-CO<sub>2</sub> extraction were used to dissolve Organic and inorganic components in coal. Thus, by using SEM, LTGA-N<sub>2</sub> apparatus and XRD, the characteristics of pore parameter and fractal dimension variation were discussed. The research results show that, the APS of samples THF, HCL-HF and Y-C increase, while the total PV decreases and the pore connectivity deteriorates. The pore connectivity of Samples THF and HCL-HF is improved (THF-C, HCL-HF-C), but the total pore volume continuously reduces. In addition, solvents treatment and SC-CO<sub>2</sub> extraction mainly act on the microporous fraction. After solvents pretreatment, the changes in the pore size distribution curves are mainly manifested in the reduction of number of micropores, especially in the micropores around 3–4 nm. There is a small increase in micropores for samples Y-C and HCL-HF-C, with the pore size mainly concentrated around 4 nm, while the pores of the sample THF-C mainly show an increase within the scope of 3–16 nm. Generally, solvent pretreatment and SC-CO<sub>2</sub> extraction help to simplify pore structure. However, the sample HCL-HF-C shows opposite change characteristics. In a short period of time, the larger pore fractal dimension, the less beneficial it is to the flow of CO<sub>2</sub>, while pore fractal dimension becomes progressively less useful in assessing pore connectivity with increasing time. |
| first_indexed | 2024-04-24T18:16:11Z |
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| language | English |
| last_indexed | 2024-04-24T18:16:11Z |
| publishDate | 2024-02-01 |
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| record_format | Article |
| series | Fractal and Fractional |
| spelling | doaj.art-b9b9a530522a42af99c3a363cf9cd1562024-03-27T13:42:03ZengMDPI AGFractal and Fractional2504-31102024-02-018314110.3390/fractalfract8030141Changes in Pore Structure and Fractal Characteristics of Solvents Pretreated High-Rank Coal under Supercritical CO<sub>2</sub>Yong Li0Xiaodong Zhang1Yijuan Sun2Zhen Wang3Shuo Zhang4Binghui Li5School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, ChinaSchool of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, ChinaInstitute of Environmental Geology, Hebei Coal Geology Bureau, Shijiazhuang 050091, ChinaSchool of Earth, Atmosphere & Environment, Monash University, Melbourne 3800, AustraliaSchool of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, ChinaThe Frist Institute of Resources and Environment Investigation of Henan Province, Zhengzhou 450000, ChinaCO<sub>2</sub> injection in coal seams, which is a significant initiative to mitigate environmental problems caused by greenhouse gases, often leads a sequence of changes in the physical properties of coal reservoirs. To look into how the pore structure changes in the process of CO<sub>2</sub> sequestration, we selected fresh coal from Huoerxinhe coal mine in China as the object. Then, acid treatment and SC-CO<sub>2</sub> extraction were used to dissolve Organic and inorganic components in coal. Thus, by using SEM, LTGA-N<sub>2</sub> apparatus and XRD, the characteristics of pore parameter and fractal dimension variation were discussed. The research results show that, the APS of samples THF, HCL-HF and Y-C increase, while the total PV decreases and the pore connectivity deteriorates. The pore connectivity of Samples THF and HCL-HF is improved (THF-C, HCL-HF-C), but the total pore volume continuously reduces. In addition, solvents treatment and SC-CO<sub>2</sub> extraction mainly act on the microporous fraction. After solvents pretreatment, the changes in the pore size distribution curves are mainly manifested in the reduction of number of micropores, especially in the micropores around 3–4 nm. There is a small increase in micropores for samples Y-C and HCL-HF-C, with the pore size mainly concentrated around 4 nm, while the pores of the sample THF-C mainly show an increase within the scope of 3–16 nm. Generally, solvent pretreatment and SC-CO<sub>2</sub> extraction help to simplify pore structure. However, the sample HCL-HF-C shows opposite change characteristics. In a short period of time, the larger pore fractal dimension, the less beneficial it is to the flow of CO<sub>2</sub>, while pore fractal dimension becomes progressively less useful in assessing pore connectivity with increasing time.https://www.mdpi.com/2504-3110/8/3/141low-volatile bituminous coalsolventSC-CO<sub>2</sub>low temperature liquid nitrogenfractal characteristics |
| spellingShingle | Yong Li Xiaodong Zhang Yijuan Sun Zhen Wang Shuo Zhang Binghui Li Changes in Pore Structure and Fractal Characteristics of Solvents Pretreated High-Rank Coal under Supercritical CO<sub>2</sub> Fractal and Fractional low-volatile bituminous coal solvent SC-CO<sub>2</sub> low temperature liquid nitrogen fractal characteristics |
| title | Changes in Pore Structure and Fractal Characteristics of Solvents Pretreated High-Rank Coal under Supercritical CO<sub>2</sub> |
| title_full | Changes in Pore Structure and Fractal Characteristics of Solvents Pretreated High-Rank Coal under Supercritical CO<sub>2</sub> |
| title_fullStr | Changes in Pore Structure and Fractal Characteristics of Solvents Pretreated High-Rank Coal under Supercritical CO<sub>2</sub> |
| title_full_unstemmed | Changes in Pore Structure and Fractal Characteristics of Solvents Pretreated High-Rank Coal under Supercritical CO<sub>2</sub> |
| title_short | Changes in Pore Structure and Fractal Characteristics of Solvents Pretreated High-Rank Coal under Supercritical CO<sub>2</sub> |
| title_sort | changes in pore structure and fractal characteristics of solvents pretreated high rank coal under supercritical co sub 2 sub |
| topic | low-volatile bituminous coal solvent SC-CO<sub>2</sub> low temperature liquid nitrogen fractal characteristics |
| url | https://www.mdpi.com/2504-3110/8/3/141 |
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