金属有机框架材料中CO2/N2吸附与分离的理论研究

金属有机框架(MOFs)材料在CO₂的捕获与分离方面受到广泛关注。本工作结合分子动力学(MD)和巨正则蒙特卡洛(GCMC)模拟方法探究了一种MOFs材料DUT-49的负性气体吸附过程及结构转变对CO₂/N₂吸附分离行为的影响。结果表明: 在20~60 MPa的压强下, DUT-49均发生可稳定存在的结构变形, 实现开孔(DUT-49-op)和闭孔(DUT-49-cp)状态的转变。DUT-49气体吸附量随温度升高而下降。DUT-49-cp的框架收缩, 气体有效吸附位点减少, 吸附量明显降低。此外, 与DUT-49-op相比, DUT-49-cp中CO₂/N₂选择性明显降低, 且随温度升高而下降, 不利于气体分离。本工作的研究结果为吸附剂材料的开发提供了科学依据。

Adsorption and Separation of CO2/N2 in Metal Organic Frameworks: a Theoretical Investigation

Metal organic frameworks (MOFs) materials have received extensive attention in capture and separation of CO₂. Herein, molecular dynamic simulation (MD) and grand canonical Monte Carlo (GCMC) simulation were used to investigate the process of negative gas adsorption to DUT-49, an MOF, and the effect of structural transition on the CO₂/N₂ adsorption and separation behavior. Results showed that DUT-49 underwent stable structural deformation at 20-60 MPa, with a transition between open pore (DUT-49-op) and closed pore (DUT-49-cp). Its adsorption capacity decreased with the increase of temperature. DUT-49-cp owned a contractive framework, exhibiting a considerably decreasing adsorption capacity due to reduction of effective adsorption sites. In addition, its selectivity decreased significantly compared with that of DUT-49-op, and decreased with increase of temperature, which is not conducive to gas separation. The present study provides a scientific basis for the development of adsorbent materials.