Altintas Cigdem, Avci Gokay, Daglar Hilal, Gulcay Ezgi, Erucar Ilknur, Keskin Seda
Department of Chemical and Biological Engineering , Koc University , Rumelifeneri Yolu, Sariyer , Istanbul , 34450 , Turkey . Email:
Department of Mechanical Engineering , Faculty of Engineering , Ozyegin University , Cekmekoy , Istanbul , 34794 , Turkey.
J Mater Chem A Mater. 2018 Apr 14;6(14):5836-5847. doi: 10.1039/c8ta01547c. Epub 2018 Mar 15.
Design of new membranes having high H/CH selectivity and high H permeability is strongly desired to reduce the energy demand for H production. Metal organic frameworks (MOFs) offer a great promise for membrane-based gas separations due to their tunable physical and chemical properties. We performed a high-throughput computational screening study to examine membrane-based H/CH separation potentials of 4240 MOFs. Grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations were used to compute adsorption and diffusion of H and CH in MOFs. Simulation results were then used to predict adsorption selectivity, diffusion selectivity, gas permeability and membrane selectivity of MOFs. A large number of MOF membranes was found to outperform traditional polymer and zeolite membranes by exceeding the Robeson's upper bound for selective separation of H from CH. Structure-performance analysis was carried out to understand the relations between MOF membranes' selectivities and their pore sizes, surface areas, porosities, densities, lattice systems, and metal types. Results showed that MOFs with pore limiting diameters between 3.8 and 6 Å, the largest cavity diameters between 6 and 12 Å, surface areas less than 1000 m g, porosities between 0.5 and 0.75, and densities between 1 and 1.5 g cm are the most promising membranes leading to H selectivities >10 and H permeabilities >10 Barrer. Our results suggest that monoclinic MOFs having copper metals are the best membrane candidates for H/CH separations. This study represents the first high-throughput computational screening of the most recent MOF database for membrane-based H/CH separation and microscopic insight provided from molecular simulations will be highly useful for the future design of new MOFs having extraordinarily high H selectivities.
为降低制氢的能源需求，人们强烈希望设计出具有高H/CH选择性和高H渗透性的新型膜。金属有机框架（MOF）因其可调节的物理和化学性质，在基于膜的气体分离方面具有巨大潜力。我们进行了一项高通量计算筛选研究，以考察4240种MOF基于膜的H/CH分离潜力。采用巨正则蒙特卡罗（GCMC）和分子动力学（MD）模拟来计算H和CH在MOF中的吸附和扩散。然后利用模拟结果预测MOF的吸附选择性、扩散选择性、气体渗透性和膜选择性。发现大量MOF膜的性能优于传统聚合物膜和沸石膜，超过了从CH中选择性分离H的罗伯逊上限。进行了结构-性能分析，以了解MOF膜的选择性与其孔径、表面积、孔隙率、密度、晶格系统和金属类型之间的关系。结果表明，孔径限制直径在3.8至6 Å之间、最大空穴直径在6至12 Å之间、表面积小于1000 m²/g、孔隙率在0.5至0.75之间且密度在1至1.5 g/cm³之间的MOF是最有前景的膜，其H选择性>10且H渗透率>10 Barrer。我们的结果表明，含铜金属的单斜MOF是H/CH分离的最佳膜候选材料。这项研究代表了对最新MOF数据库进行的首次基于膜的H/CH分离高通量计算筛选，分子模拟提供的微观见解将对未来设计具有极高H选择性的新型MOF非常有用。
