煤的溶剂萃取物成分及对煤吸附甲烷特性影响

Analysis of extracts and effects of them on methane adsorption characteristics of coal

煤中有机小分子相是煤的重要组成部分,为分析其对煤吸附甲烷的影响,在常压下(50℃),采用正己烷对张集和大柳塔煤样分别进行微波辅助萃取,得到萃取后煤样(残煤)和萃取物。采用GC/MS分析萃取物成分,并依此选取柴油作为正己烷萃取物的模型物,配置含柴油煤样(简称含油煤),开展了原煤、残煤和含油煤的甲烷等温吸附实验。研究结果表明:原煤和残煤吸附瓦斯在低压阶段差异不大,随着压力的增大,原煤吸附甲烷量逐渐高于残煤;含油煤则不同,压力较大时,同一压力段的瓦斯吸附增量高于原煤和残煤,低压时吸附甲烷量虽小于原煤和残煤,但随着压力的增大,最终吸附甲烷量略高于原煤。用Langmuir和Langmuir-Henry二元吸附模型对等温吸附数据进行拟合,得出煤吸附甲烷可分为2个过程,低压阶段主要为符合Langmuir模型的煤基质表面吸附,高压阶段主要为符合Henry模型的渗入煤基质的内部(孔隙、内表面)吸附;且煤中有机小分子有助于提高煤高压阶段的甲烷吸附量。

To study the effects of organic micromolecules in coal on methane adsorption characteristics,organic micromolecules were extracted by n-hexane using microwave assisted method from coal samples to obtain the residual coal samples at 50 ℃ and atmospheric pressure. And their extracts were analyzed via the Gas Chromatography / Mass Spectrometry( GC / MS). And on this basis,the diesel was chosen to be as models for n-hexane extracts of coals and was used to add to coals. Methane sorption isotherms on raw coals,their residues and coals added diesel were tested. The results show that:At low pressure,the difference of gas adsorption between raw coals and their residues is insignificant,while as the pressure increases,the amount of coal methane adsorption is gradually higher than its residues;Different from raw coal and their residues,at greater pressure,gas absorption increment for coal added diesel is more higher under the same pressure section,and as the pressure increases,the final amount of methane adsorb slightly higher than raw coals. For all coal samples examine,experimental date are fit by the Langmuir and Langmuir-Henry dual-model,which suggests that methane sorption by the coal samples can be explained by adsorption on the surfacethat occurred at low pressures described by a Langmuir isotherm and at high pressures,penetration( dissolution) into the bulk described by Henry's law,and organic micromolecules in coal are help for increasing the amount of coal methane adsorption at high pressures.