超临界CO2对烟煤和无烟煤化学结构的影响  

The effects of supercritical CO_2 on the chemical structure of bituminous coal and anthracite

作　　者：刘世奇[1] 王恬 杜艺 方辉煌 王鹤 LIU Shiqi;WANG Tian;DU Yi;FANG Huihuang;WANG He(The Key Laboratory of Coal-based CO2 Capture and Geological Storage,Jiangsu Province,Low Carbon Energy Institute,China University of Mining and Technology,Xuzhou 221008,China;Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process,Ministry of Education,School of Resource and Geoscience,China University of Mining and Technology,Xuzhou 221116,China)

机构地区：[1]中国矿业大学低碳能源研究院,江苏省煤基CO2捕集与地质存储重点实验室,江苏徐州221008 [2]中国矿业大学资源与地球科学学院,煤层气资源与成藏过程教育部重点实验室,江苏徐州221116

出　　处：《煤田地质与勘探》2018年第5期19-25,共7页Coal Geology & Exploration

基　　金：国家自然科学基金项目(41402135,41330638,41727801);江苏省基础研究计划(自然科学基金)面上项目(BK20171188);国家留学基金项目(201706425014)

摘　　要：超临界CO_2对煤化学结构的改造对煤层CO_2封存能力极为关键。论文开展了模拟埋深1 500 m(62.5℃、15MPa)条件下4组不同变质程度煤的ScCO_2-H_2O体系与煤岩地球化学反应实验。通过傅里叶变换红外光谱和X射线粉末衍射实验获得了反应前后煤化学结构演化特征,探讨了煤化学结构演化的机理。结果表明:ScCO_2作用后,煤中脂肪烃链长度普遍增加,仅肥煤的芳香烃丰度增大,肥煤、瘦煤和贫煤含氧基团丰度的增大主要由氢键基团含量的增加贡献,无烟煤含氧基团丰度则主要受低分子化合物溶出的影响。ScCO_2引起的溶胀作用造成肥煤和瘦煤芳香层面之间交联键断裂,芳香微晶内部结构疏松,而芳香层面内CAr-CAr交联的形成提高了肥煤和瘦煤芳香性和芳香环缩合度;贫煤和无烟煤中非稠合多苯结构脱落使芳香微晶内部更紧凑,脂肪烃链长度的增加则降低了贫煤和无烟煤芳香性和芳香环缩合度。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.

关 键 词：芳香微晶 有机基团 脂肪烃 交联键 溶胀作用 超临界CO2 

分 类 号：P618.11[天文地球—矿床学]