低分子化合物与煤的氮吸附行为

EFFECT OF LOW MOLECULAR WEIGHT COMPOUNDS IN COAL STRUCTURE ON BEHAVIOR OF COAL-NITROGEN ADSORPTION

煤的分子结构与瓦斯吸附性能关系密切.采用正己烷、苯、氯仿、四氢呋喃和吡啶等五种极性依次增强的溶剂,对平顶山烟煤进行索氏萃取,测试原煤及其不同极性溶剂萃余物的氮吸附行为,研究煤中低分子化合物对煤氮吸附行为的影响.结果表明,五种溶剂的萃取率依次增加,当相对压力pr(pr指吸附平衡压力与吸附质饱和蒸汽压比值)小于0.1时,五种溶剂萃余物的吸附量依次升高,当pr大于0.1时,苯、氯仿萃余物的吸附量迅速增高,明显大于四氢呋喃萃余物的吸附量.据此推测,煤中低分子化合物的含量和组成不仅改变了煤的孔径分布,还改变了煤的表面性质,其中可溶性极性芳烃化合物对煤的吸附行为影响最大,含氧和氮的杂环芳烃混合物次之,饱和烃类化合物影响最小.

The capability of methane absorbed by coal has a close relation with the molecular structure of coal. In order to study the effect of low molecular weight compounds in coal on behaviors of coal-nitrogen adsorption, Pingdingshan bituminous coal were extracted with five kinds of organic solvents using Soxhlet extraction, the solvents including n-hexane, benzene, chloroform, tetrahydrofuran and pyridine, and the polarity of solvents increased in turn, whereafter, the raw coal and its residuals adsorption behaviors of nitrogen were investigated. The studies show that the extraction yields of the five solvents increased in turn, when the relative pressure Pr （relative pressure was the ratio of adsorption equilibrium pressure and the saturated vapor pressure of nitrogen） less than 0. 1, the nitrogen adsorption capacity of coal residuals increased in turn, but when relative pressure Pr larger than 0.1, compared with tetrahydrofuran residuals, benzene and chloroform residuals have high nitrogen adsorption capacity. The results show that the contents and constituents of low molecular weight compounds have a significant effect on coal adsorption behaviors of nitrogen, both aperture property and surface property were changed. The soluble polar aromatic compounds have the most effect on the behaviors of coal-nitrogen adsorption, the heterocyclic oxygen and nitrogen aromatic compounds have the inferior effect on it, and the saturated hydrocarbon compounds at least.