溶剂萃取对烟煤孔隙结构和粒度的影响

溶剂萃取对烟煤孔隙结构和粒度的影响

  • 摘要: 用二硫化碳-N-甲基-2-吡咯烷酮(CS2-NMP)(1∶1, V/V) 混合溶剂、丙酮和吡啶对南桐烟煤逐级萃取,得到各级残余物。通过比表面积及孔快速测试仪和扫描电镜,对煤及各萃取残余物的氮气吸附行为、粒度进行测试,考察了溶剂萃取对煤的BET比表面积与BJH孔容、孔面积随孔径分布规律以及粒度的影响。结果表明通过“溶解”小分子物质,溶剂萃取能够有效地改善煤的吸附性、比表面积和孔隙结构,降低其粒度,但不能破坏其基本结构单元,在本质上仍属于物理作用。根据最可几孔径计算出南桐烟煤胶态分子团结构模型中基本结构单元的粒径在3.5 nm左右,证实了煤分子胶态团结构模型的假设。

     

    Abstract: Nantong bituminous coal was extracted with carbon disulfide-N-methyl-2-pyrrolid-inone (CS2-NMP) mixed solvent, acetone and pyridine, and all the residue was gained. Sorption behaviors of nitrogen and granularity of the coal and extract residue, were tested using Accelerated Surface Area and Porosimetry (ASAP) 2010 apparatus and scanning electron microscope. The BET specific area of the samples, the distribution regulation of BJH pore volume and BJH pore area according to the pore radius, and the influence of the extraction behavior on the granularity were studied. The results showed that through “dissolving” the small molecule substance the solvent extraction will improve the adsorption ability, the specific area of the pore and the character of pore space, and decrease the granularity, but not break the basic structure unit of coal. The solvent extraction of coal belongs to physical behavior essentially. The specific area varies from 187 m2/g to 318 m2/g, and the pore volume varies from 0.175 m3/g to 0.535 m3/g. The most probable pore radius for the original coal and its solvent extract residua is all about 0.72 nm. According to the most probable pore radius, the diameter of basic structure unit of the coal was calculated for about 3.5 nm. The result approved the assumption on the colloidal group structure model of coal molecule.

     

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