Exceptional Hydrophobicity of a Large-Pore Metal鈥揙rganic Zeolite
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- 作者：Chun-Ting He ; Lu Jiang ; Zi-Ming Ye ; Rajamani Krishna ; Zhen-Song Zhong ; Pei-Qin Liao ; Jianqiao Xu ; Gangfeng Ouyang ; Jie-Peng Zhang ; Xiao-Ming Chen
- 刊名：Journal of the American Chemical Society
- 出版年：2015
- 出版时间：June 10, 2015
- 年：2015
- 卷：137
- 期：22
- 页码：7217-7223
- 全文大小：613K
- ISSN：1520-5126
文摘
Porous materials combining high hydrophobicity, large surface area, as well as large and uniform pore size are very useful but rare. The nanoporous zeolitic metal azolate framework, RHO-[Zn(eim)2] (MAF-6, Heim = 2-ethylimidazole), is an attractive candidate but thought to be unobtainable/unstable. In this work, the supramolecular isomerism of [Zn(eim)2] is thoroughly studied using a rapid solution mixing reaction of [Zn(NH3)4](OH)2 and Heim, which enables MAF-6 with high crystallinity, purity, and thermal/chemical stabilities to be synthesized in large quantity. Gas and vapor adsorption isotherms, gas chromatography, and water contact angle measurements, as well as transient breakthrough and molecular dynamics simulations show that MAF-6 exhibits large surface area (langmuir surface area 1695 m2 g鈥?), pore volume (0.61 cm3 g鈥?), pore size (d = 18.4 脜), and aperture size (d = 7.6 脜) with high hydrophobicity on both the internal pore and external crystal surfaces. It can barely adsorb water or be wetted by water (contact angle 143掳) but readily adsorb large amounts of organic molecules including methanol, ethanol, mesitylene, adamantane, C6鈥揅10 hydrocarbons, xylene isomers, and saturated/unsaturated analogues such as benzene/cyclohexene/cyclohexane or styrene/ethylbenzene. It can also separate these organic molecules from each other as well as from water by preferential adsorption/retention of those having higher hydrophobicity, lipophilicity, or oil/water partition coefficient. These properties are very different with other porous materials such as SOD-[Zn(mim)2] (Hmim = 2-methylimidazole, MAF-4/ZIF-8) with a hydrophobic pore surface but a hydrophilic crystal surface and small aperture size.