Erucar Ilknur, Keskin Seda
Department of Natural and Mathematical Sciences, Faculty of Engineering, Ozyegin University, Cekmekoy, 34794 Istanbul, Turkey.
Department of Chemical and Biological Engineering, Koc University, Rumelifeneri Yolu, Sariyer, 34450 Istanbul, Turkey.
Ind Eng Chem Res. 2020 Feb 19;59(7):3141-3152. doi: 10.1021/acs.iecr.9b05487. Epub 2020 Jan 21.
Metal organic frameworks (MOFs) have been considered as potential adsorbents for adsorption-based CO/CH and CO/N separations because of their high CO selectivities and high working capacities. HO in flue gas and natural gas streams affects the gas uptake capacities of MOFs. However, the presence of HO is commonly neglected in high-throughput computational screening studies while assessing the CO separation performances of MOFs. In this study, the impact of the presence of HO on the CO separation performances of 13 MOFs that were previously identified as the best adsorbent candidates among several thousands of MOFs was examined. Molecular simulations were used to compute selectivity, working capacity, regenerability, and adsorbent performance score (APS) of MOFs considering separation of binary CO/CH, CO/N, and ternary CO/CH/HO and CO/N/HO mixtures. The results showed that introduction of HO as the third component into binary CO/CH and CO/N mixtures significantly affected the adsorbent evaluation metrics of MOFs that have strong affinity toward HO because of the presence of specific functional groups and/or extra framework anions in the framework. Remarkable increases in CO/N selectivities of MOFs were observed in the presence of HO. On the other hand, simulations performed using MOFs that are preloaded with HO to mimic the exposure of MOFs to humidity prior to gas adsorption revealed drastic decreases in CO working capacities and APSs of MOFs both for CO/CH and CO/N separations. These results will be useful for the design and development of efficient MOF adsorbents for CO capture under humid conditions.
金属有机框架材料（MOFs）因其对CO的高选择性和高工作容量，被认为是基于吸附的CO/CH和CO/N分离的潜在吸附剂。烟道气和天然气流中的H₂O会影响MOFs的气体吸附容量。然而，在高通量计算筛选研究中，在评估MOFs的CO分离性能时，H₂O的存在通常被忽略。在本研究中，考察了H₂O的存在对13种MOFs的CO分离性能的影响，这13种MOFs先前在数千种MOFs中被确定为最佳吸附剂候选物。使用分子模拟来计算MOFs的选择性、工作容量、再生性和吸附剂性能得分（APS），考虑二元CO/CH、CO/N以及三元CO/CH/H₂O和CO/N/H₂O混合物的分离。结果表明，将H₂O作为第三组分引入二元CO/CH和CO/N混合物中，会显著影响由于骨架中存在特定官能团和/或额外骨架阴离子而对H₂O具有强亲和力的MOFs的吸附剂评估指标。在H₂O存在的情况下，观察到MOFs的CO/N选择性显著增加。另一方面，使用预先负载H₂O的MOFs进行模拟，以模拟MOFs在气体吸附之前暴露于湿度环境的情况，结果表明，对于CO/CH和CO/N分离，MOFs的CO工作容量和APS都大幅下降。这些结果将有助于设计和开发在潮湿条件下用于CO捕获的高效MOF吸附剂。
