不同孔径活性炭吸附挥发性有机物的分子模拟

Molecular simulation of adsorption of volatile organic compounds by activated carbon with different pore sizes

借助Materials Studio软件建立了0.902nm、1.997nm、3.000nm、4.000nm孔径的活性炭狭缝孔模型,采用巨正则蒙特卡洛模拟(Grand Canonical Monte Carlo)的模拟方法计算了其对挥发性有机物(VOCs,如异己烷、苯、甲苯、丙酮和甲醇)的吸附数据,考察了活性炭孔径的变化对VOCs吸附性能的影响,并对实际应用进行指导。模拟结果显示:活性炭对VOCs的吸附受孔径和吸附能的共同影响,在293.15K、各物质饱和蒸气压p0下,随着孔径的增大,吸附质吸附剂之间的亲和力呈下降趋势。活性炭孔径由0.902nm增加到4.000nm对异己烷、苯、甲苯的饱和吸附量逐渐增大,而4.000nm孔径活性炭对丙酮饱和吸附量小于3.000nm孔径活性炭,3.000nm、4.000nm孔径活性炭对甲醇饱和吸附量小于1.997nm孔径活性炭。在工业废气VOCs吸附回收中选择0.902~1.997nm孔径活性炭能够达到最佳效果。

The activated carbon slit pore model of 0.902nm,1.997nm,3.000nm and 4.000nm pore size was established by the Materials Studio software.The adsorption data of volatile organic compounds(VOCs:isohexane,benzene,toluene,acetone,and methanol)was simulated by the method of Grand Canonical Monte Carlo(GCMC)simulation.The effect of changes on the adsorption performance of VOCs guides practical applications.The simulation results showed that the adsorption of VOCs by activated carbon is affected by the pore size and adsorption energy.Under the saturated vapor pressure p0 of 293.15K,the affinity between the adsorbents decreases with the increase of the pore size.The pore size of activated carbon increased from 0.902nm to 4.000nm,and the saturated adsorption capacity of isohexane,benzene and toluene increased gradually,while the adsorption capacity of 4.000nm pore size activated carbon to acetone was less than 3.000nm,and the adsorption capacity of 3.000nm and 4.000nm pore size activated carbon to methanol was less than the 1.997nm.In the industrial waste gas VOCs adsorption recovery,the choice of 0.902—1.997nm pore size activated carbon can achieve the best results.