杂质对金属-有机骨架材料分离烟道气性能影响的分子模拟研究

Molecular Simulation of Effects of Impurities on Flue Gas Separation in Metal-Organic Frameworks

采用分子模拟方法系统研究了杂质(水、O2和SO2)对5种金属-有机骨架材料(ZIF-8,NOTT-300,UiO-66(Zr),UiO-66-NH2和UiO-66-2COOH)的烟道气分离性能的影响,并探讨了其微观机理.结果表明,O2和SO2对这些材料的CO2/N2分离选择性影响不大;水对ZIF-8和UiO-66(Zr)的分离选择性影响不大,而对NOTT-300和UiO-66-NH2的分离选择性具有提升作用;UiO-66-2COOH对CO2的选择性有所降低.在干燥的环境下,UiO-66-2COOH的选择性最高,而在湿润的环境下,UiO-66-NH2的选择性最高.为捕获CO2的新型材料设计提供理论指导.

The resulting excessive release of CO2 into the atmosphere has triggered great change in the climate which calls for urgent cuts in the emission of such primary anthropogenic greenhouse gas. In this regard, one significant challenging separation problem nowadays is associated with the selective CO2 capture from the flue gas emitted by large stationary point sources such as power plants. In this work, a computational study was performed to systematically investigate the effects of impurities（ H2 O, O2 and SO2 ） on the performance of five metal-organic frameworks（MOFs）[ZIF-8, NOTT-300, UiO-66（Zr）, UiO-66-NH2 and UiO-66-2COOH] for the separation of flue gas under the industrial conditions, and the underlying microscopic mechanisms were also explored. The accuracy of the force fields adopted was verified by comparing the simulated adsorption isotherms with those experimental data. Then, molecular simulations were performed to investigate the separa-tion behavior of flue gas consisting of CO2 , N2 , O2 , SO2 and H2 O in these materials. The results show that O2 and SO2 have a negligible influence on the CO2/N2 selectivity of the MOFs. Water has a negligible effect on the separation performance of ZIF-8 and UiO-66 （ Zr） and can enhance the CO2/N2 selectivity of NOTT-300 and UiO-66-NH2 . However, the separation ability of UiO-66-2COOH is weakened in the presence of water. The current study demonstrates that the UiO-66-2COOH can be a promising candidate for selective CO2 separa-tion from dried flue gas, while UiO-66-NH2 can be a good candidate for the separation of moist flue gas. The information obtained in current study could provide a theoretical guidance for the design of novel CO2 capture materials.