钾掺杂单壁碳纳米管吸附CO_2气体的Monte Carlo模拟研究

Monte Carlo simulation of CO_2 adsorption in K-doped single-walled carbon nanotubes

减少化工企业对大气层的二氧化碳(CO_2)排放量以避免温室效应仍然是当前环境保护的重要任务之一.为促进研发储存和分离CO_2的纳米材料,采用巨正则蒙特卡洛(Monte Carlo)方法模拟了温度为300K时一系列压强下CO_2气体在不同类型的钾掺杂单壁碳纳米管中的吸附情况.结果表明:碱金属钾的掺杂可以在一定条件下显著提高碳纳米管对CO_2气体的吸附能力.由等温吸附曲线和吸附热曲线可知,多数情况下钾原子的掺杂量越大、钾原子嵌入管壁越深,则吸附能力越强.然而必须注意,某一压强下钾掺杂碳纳米管对CO_2气体的吸附量不仅受纳米管和气体分子之间的作用力强度的影响,还取决于吸附空间的大小;特定压强下的吸附量是这两种因素综合作用的结果.

Reducing CO2 emissions from the petrochemical companies to the atmosphere to avoid the greenhouse effect is still one of the important tasks of environmental protection.In order to promote the research and development of nanomaterials for storage and separation of CO2,in this work we use the grand-canonical Monte Carlo(GCMC)method to simulate,at the temperature of 300 K,the adsorption of CO2 in different types of K-doped single-walled carbon nanotubes under a series of pressures.It shows that the doping of alkali metal K can significantly increase the adsorption capacity of carbon nanotubes for CO2.The adsorption curves and the adsorption heat curves show that,in general,the greater the doping of K and the deeper the K atoms are embedded into the nanotube wall,the stronger the adsorption capacity of nanotubes is.However,it must be noted that K-doped carbon nanotubes are effective for CO2 at specific pressures.The amount of gas adsorbed is not only affected by the strength of the interaction between nanotubes and gas molecules,but also determined by the size of the adsorption space;the adsorption capacity at a certain pressure is the result of the combined effect of these two factors.