甲烷沉积法对甲烷/氮气分离炭分子筛性能的研究

Effect of CH_4 Sedimentary Conditions on Performance of Carbon Molecular Sieve in Methane/Nitrogen Separation Process

高性能甲烷/氮气分离用炭分子筛是保证低浓度煤层气变压吸附分离的前提。以椰壳炭化料为原料在一定条件下活化制备了炭前驱体,以甲烷为沉积剂通过气相炭沉积调孔制备炭分子筛,考察沉积时间、沉积温度、沉积剂浓度和沉积剂量对变压吸附分离甲烷/氮气效果的影响,采用N2吸附法分析了炭前驱体的比表面积和孔径分布。结果表明:炭化时间40 min,活化温度850℃,活化时间120 min,水蒸气流量1.71 g/min时得到的炭前驱体微孔发达。以甲烷作为沉积剂时,甲烷/氮气的分离效果随着沉积温度的升高而显著增大;沉积时间、沉积温度和甲烷浓度对甲烷/氮气的分离效果影响不大。最适宜沉积条件为:沉积温度850℃,CH4浓度20.6%,CH4混合气流速为1200 mL/min,沉积时间120 min。

Carbon molecular sieve with high methane/nitrogen separation performance is the premise for low concentration coalbed methane separation by swing pressure adsorption.Coconut shell carbonized materials was used as raw material in this paper.The raw material was activated to prepare carbon precursor,and then deposited by CH4 to prepare carbon molecular sieve（CMS）.The effects of deposition time,deposition temperature,CH4 concentration and velocity in CH4/N2 mixture on the separation performance of CMS in methane/nitrogen separation process using pressure swing adsorption（PSA） were studied.N2 adsorption method was used to analyze the specific surface area and pore size distribution of carbon precursor.The results show that carbon precursor prepared under carbonization time 40 min,activation temperature 850 ℃,activation time 120 min,and steam flowing 1.71 g/min has higher micropores than that under other preparation conditions.The concentration of separated methane and nitrogen increases with the increase of the deposition temperature significantly,deposition time,sedimentary agent concentration and sedimentary dosage have little influence on the concentration of separated methane and nitrogen.The optimal sedimentary conditions are： deposition temperature 850 ℃,CH4 concentration 20.6%,CH4 gas mixture flow rate 1 200 mL/min,deposition time 120 min.