Exploiting hydrophobicity and hydrophilicity in nanopores as a design principle for “smart” MOF microtanks for methane storage
Exploiting hydrophobicity and hydrophilicity in nanopores as a design principle for “smart” MOF microtanks for methane storage
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DOI：
10.1039/c9me00072k
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发表时间：
2020-01
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通讯作者：
Ryther Anderson;Bomsaerah Seong;Zöe Peterson;Molly Stevanak;Moises A. Carreon;Diego A. Gómez-Gualdrón
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作者：
Ryther Anderson;Bomsaerah Seong;Zöe Peterson;Molly Stevanak;Moises A. Carreon;Diego A. Gómez-Gualdrón
甲烷动力车辆的广泛使用可能需要开发有效的车载甲烷存储系统。一种新的甲烷储存概念是纳米多孔微罐，它是基于一个毫米大小的纳米多孔颗粒（核心）周围的生物膜（外壳）。理想化孔隙中的混合物吸附模拟表明，通过将具有大的疏水性孔隙的颗粒与具有小的亲水性孔隙的膜相结合，可以在颗粒中捕获大量的“加压”甲烷，同时保持外部压力较低。甲烷将通过用亲水性化合物如甲醇的吸附密封周围的膜而被捕获。在超过2000个假设的金属有机框架（MOF）中的额外模拟表明，上述设计概念可以使用真实的纳米多孔材料来开发。从这些模拟中得到的结构-性质关系表明，适合于核（每cc储存超过250 cc（STP）CH 4）的M0 F应具有12-14 A范围内的孔径和没有明显亲水部分的连接基。另一方面，适用于壳的M0 F应具有小于9 A的孔径和具有亲水官能团如-CN、-N 02、-OH和-NH 2的连接基。模拟快照表明，这些基团和甲醇的亲水部分之间的氢键对于密封功能是至关重要的。
Widespread use of methane-powered vehicles likely requires the development of efficient on-board methane storage systems. A novel concept for methane storage is the nanoporous microtank, which is based on a millimeter-sized nanoporous pellet (the core) surrounded by an ultrathin membrane (the shell). Mixture adsorption simulations in idealized pores indicate that by combining a pellet that features large, hydrophobic pores with a membrane featuring small, hydrophilic pores, it would be possible to trap a large amount of “pressurized” methane in the pellet while keeping the external pressure low. The methane would be trapped by sealing the surrounding membrane with the adsorption of a hydrophilic compound such as methanol. Additional simulations in over 2000 hypothesized metal–organic frameworks (MOFs) indicate that the above design concept could be exploited using real nanoporous materials. Structure–property relationships derived from these simulations indicate that MOFs suitable for the core (storing over 250 cc(STP)CH4 per cc) should have a pore size in the 12–14 A range and linkers without appreciably hydrophilic moieties. On the other hand, MOFs suitable for the shell should have a pore size less than 9 A and linkers with hydrophilic functional groups such as –CN, –NO2, –OH and –NH2. Simulation snapshots suggest that the hydrogen bonding between these groups and hydrophilic moieties of methanol would be critical for the sealing function.