镜煤有机溶剂二级抽提孔隙结构及吸附性差异

Differences in Pore Structures and Adsorptivity between Raw and Two-step-solvent-extracted Vitrains

基于黔西—滇东5套镜煤及其有机溶剂二级抽余物的压汞和等温吸附实验结果,对比分析了原煤及其有机溶剂抽余物孔隙结构、吸附性差异及其影响因素。结果表明,抽提作用改变了镜煤孔隙结构,二硫化碳一级抽提煤岩孔结构改造受煤级控制,在煤级第二次跃变之前表现为增孔效应,之后表现为扩孔效应;苯二级抽提总体表现为扩孔效应。抽提作用同样改变了镜煤吸附性,改变方向和幅度取决于煤化程度的高低,在第二次煤化作用跃变之前,有机溶剂抽提作用增强了煤岩吸附性;在第二次煤化作用跃变之后,抽提作用减弱了煤岩吸附性。发现镜煤抽余物的吸附能力变化率与其微孔表面积变化率和孔容变化率存在较好的正相关关系;与总孔、大孔、中孔和过渡孔孔容变化率总体成负相关关系,与其表面积变化率总体也成负相关关系。认为第二次煤化作用跃变对镜煤抽余物孔隙结构和吸附性改变起关键作用;同时佐证了煤岩吸附气体主要通过微孔表面实现。研究还注意到,有机溶剂的抽提作用对煤孔隙结构乃至吸附性的改造可能与煤岩微观层次的大分子结构相关,其机理有待进一步探讨。

Based upon the data of mercury intrusion and methane isothermal adsorption of 5sets of raw and two-step-extracted coals from western Guizhou and eastern Yunnan,the differences and influence factors of pore structure and adsorptivity between raw and solvent-extracted coals were comparatively discussed.The results show that the extraction changes vitrain pore structure.Coal rank controls the pore structure changes of carbon disulfide extracted coal,the extraction increases and enlarges the pore number and volume before and after the second coalification jump,respectively.The benzene extraction enlarges vitrain pore volume in all.The extraction also changes vitrain adsorptivity,but the change direction and magnitude depends on the coalification degree;the extraction of organic solvent enhances and reduces vitrain adsorptivity before and after the second coalification jump,respectively.It was found that the adsorptivity of extracted vitrain change has a positive relationship with the changes of the pore special surface area and/or volume,and it has a negative relationship to that of the total,macro,middle and transitional pore volume and special surface.It was considered that the second coalification jump plays a key role on the changes of the pore structure and the adsorptivity,and it evidenced that the methane adsorption happened in the surface area of coal micro pore.In addition,it was also suggested that the alteration of the organic extraction to the pore structure and adsorptivity of coal may involve the micro pore related to the macro-molecular structure of coal,which is worthy of further investigation.