不同溶剂对高阶煤的表面性及孔隙性的改造机理研究
Study on reconstruction mechanism of different solvent to surface andporosity of high rank coal
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摘要: 为了探索新型有机压裂液中有机溶剂对高阶煤的作用效果,采用不同类型的有机溶剂对山西长治的高阶煤进行溶剂萃取,借助接触角和低温液氮吸附试验的测定结果,分析了不同溶剂改造下高阶煤表面性和孔隙性的差异性变化及其原因。研究结果表明:有机溶剂作用后,煤-水接触角显著变大,表面张力明显减小,说明处理后煤样的疏水性增强;不同溶剂作用后,煤样的BET比表面积和BJH孔容不同程度地增大,其中,丙酮改造后的煤样增幅最大;有机溶剂对煤样均有扩孔作用,且对微孔的扩孔效果最为明显;相比而言,二硫化碳、丙酮和过氧乙酸作用后的煤样的开放孔、大孔含量显著增多,孔隙连通性明显改善,而四氢呋喃、三乙胺和乙醇溶剂对煤样孔隙性的改善程度相对较弱。Abstract: In order to discover the organic solvent effect in the new organic fracturing fluid to the high rank coal, different organic solvents were applied to the solvent extraction of the high rank coal from Changzhi, Shanxi. With the measured results of the contact angel and cryogenic nitrogen adsorption experiment, an analysis was conducted on the surface and porosity difference variation and causes of the high rank coal under the different solvent reconstruction. The study result showed that after the effect of the organic solvent, the coal-water contract angle would be obviously increased, the surface tension would remarkably decreased and the above showed that after the treatment, the hydrophobicity of the coal samples was enhanced. After the treatment of the different solvent, the BET specific surface area and the BJH specific pore volume of the coal samples would be increased in different degree. Among them, after the reconstruction with the acetone, the coal sample volume was increased in largest. The organic solvent would have the pore enlarged effect of the coal sample and the pore enlarged effect of the micro pore would be obvious. By a comparison, after the carbon disulfide, acetone and peracetic acid treated, the open pore and large pore content of the coal sample would be obviously increased and connection of the pores would be obviously improved. The tetrahydrofuran, triethylamine and ethanol solvents would have weaker improvement to the coal sample pores.