活性炭孔结构对煤层甲烷选择吸附行为的影响

Effect of Pore Structure of Activated Carbon on Selective Adsorption of Coal-Bed Methane

采用不同含量的过氧化氢溶液和硝酸溶液对商用活性炭AC-1进行改性并经He-H2高温热处理,同时对石油焦活性炭进行了He-H2高温热处理以作为对比。采用低温N2物理吸附、TPD和Boehm酸碱滴定等手段对活性炭进行了表征。以甲烷和N2混合气为煤层甲烷模型气,考察了活性炭孔道结构对甲烷选择吸附行为的影响。实验结果表明,不同改性方法对活性炭孔道结构的改变有明显的影响,经He-H2高温热处理后不同的活性炭具有相似的表面化学性质;活性炭的孔径是选择吸附甲烷的首要因素,最佳孔径范围为0.71～0.74 nm;微孔比表面积决定了甲烷的吸附容量,微孔比表面积越大,甲烷富集容量越大。

Activated carbon was modified with HNO3 and H2O2, and by thermal treatment in He- H2 to improve its pore structure, which was beneficial to the adsorption of coal-bed methane on it. The modified activated carbons were characterized by means of the physical adsorption of N2 at 77 K, TPD and Boehm titration. It was shown that the modifications affected the pore structure of the samples significantly, while the superficial chemical properties were similar after the thermal treatment in He- ll2. Pore diameter is the major factor affecting the selective adsorption of methane on the activated carbons, and the optimum pore diameter is in the range of 0.71-0.74 nm. The specific surface area of the micropores affects the adsorption capacity of the activated carbons, and the amount of the enriched methane increases with the increase of the specific surface area.