Effects of supercritical CO2 on micropores in bituminous and anthracite coal
Effects of supercritical CO2 on micropores in bituminous and anthracite coal
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超临界CO2对烟煤和无烟煤微孔的影响
DOI：
10.1016/j.fuel.2019.01.008
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发表时间：
2019-04-15
期刊：
影响因子：
7.4
通讯作者：
Fang, Huihuang
中科院分区：
文献类型：
--
作者：
Liu, Shiqi;Sang, Shuxun;Fang, Huihuang
超临界CO2 （ScCO2）对煤微孔的影响是决定煤层CO2容量的关键因素。为了研究不同温度和压力条件下ScCO2对不同等级煤微孔的影响，利用ScCO2地球化学反应器模拟了CO2固存过程。将4个不同等级的煤样在62.5℃、15 MPa的ScCO2和水环境下暴露240 h，进行CO2吸附试验、傅里叶变换红外光谱和x射线衍射，确定ScCO2- h2o处理前后煤样微孔的体积和孔径分布、有机基团的类型和含量以及芳香晶结构。研究了煤的化学结构和有机基团对煤微孔的影响。宽度< 0.46 nm的微孔主要与芳香层的层间间距有关。ScCO2引起的膨胀使高挥发性烟煤的杂环和非凝聚多核芳烃分离，导致宽度< 0.46 nm的微孔体积略有增加。在半无烟煤和无烟煤中，溶胀引起的低键能交联脱落和多加成反应引起的芳香层间C-Ar-C-Ar交联的形成共同导致宽度< 0.46 nm的微孔体积减小。宽度为> ~ 0.46 nm的微孔是煤大分子结构中的孔，称为分子间孔，其体积大小由芳香族晶体的定向排列和脂肪烃链长决定。高挥发性烟煤中ScCO2引起的断键通过加成和多加成反应生成新的脂肪族或芳香族化合物。这些过程增加了芳香晶的定向排列，导致微孔的体积减小，微孔的宽度为> 0.46 nm。随着煤阶的增加，ScCO2处理后煤的大分子结构以脂肪烃链长为主，导致半无烟煤和无烟煤中宽度为bb0 0.46 nm的微孔体积增加。
The effects of supercritical CO2 (ScCO2) on coal micropores play a critical role in determining the CO2 capacity of coalbeds. To investigate the effects of ScCO2 on micropores in coals of different ranks under a range of temperature and pressure conditions, CO2 sequestration processes are replicated using a ScCO2 geochemical reactor. Four samples of coal of different ranks are exposed to ScCO2 and water for 240 h at 62.5 degrees C and 15 MPa, and CO2 adsorption tests, Fourier transform infrared spectroscopy, and X-ray diffraction are performed to determine the volume and pore size distribution of the micropores, the types and contents of the organic groups, and the aromatic crystallite structures of the coal samples before and after the ScCO2-H2O treatment. The influence of the chemical structure and the organic groups of the coal on the coal micropores is then studied. Micropores with widths < 0.46 nm are mainly associated with the inter-layer spacing of the aromatic layers. Swelling caused by ScCO2 detaches heterocycles and non-condensed polynuclear aromatics of high-volatile bituminous coal, resulting in slight increases in the volume of micropores with widths < 0.46 nm. The falling off of cross-links with low bond energies caused by swelling and the formation of C-Ar-C-Ar cross-links between the aromatic layers caused by polyaddition reactions together cause a decrease in the volume of micropores with widths < 0.46 nm in semi-anthracite and anthracite coal. Micropores with widths > 0.46 nm are pores in the macromolecular structure of coal and are known as intermolecular pores, and their volumes are determined by the directional arrangement of aromatic crystallites and the aliphatic hydrocarbon chain length. The broken bonds caused by ScCO2 in high-volatile bituminous coal form new aliphatic or aromatic compounds via addition and polyaddition reactions. These processes increase the directional arrangement of aromatic crystallites, resulting in a decrease in the volume of micropores with widths > 0.46 nm. As the coal rank increases, the aliphatic hydrocarbon chain length gives priority to the macromolecular structure of coal after the ScCO2 treatment, resulting in an increase in the volume of micropores with widths > 0.46 nm in semi-anthracite and anthracite coal.