Direct Evidence of CO2 Capture under Low Partial Pressure on a Pillared Metal-Organic Framework with Improved Stabilization through Intramolecular Hydrogen Bonding
Direct Evidence of CO2 Capture under Low Partial Pressure on a Pillared Metal-Organic Framework with Improved Stabilization through Intramolecular Hydrogen Bonding
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通过分子内氢键提高稳定性的柱状金属有机框架在低分压下捕获 CO2 的直接证据
DOI：
10.1002/cplu.201600156
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发表时间：
2016
期刊：
影响因子：
3.4
通讯作者：
Xiang Shengchang
中科院分区：
文献类型：
--
作者：
Yao Zizhu;Chen Yuan;Liu Lizhen;Wu Xiaonan;Xiong Shunshun;Zhang Zhangjing;Xiang Shengchang
直接观察CO2负载的MOFs的结构有助于揭示特异性结合相互作用，从而设计出更好的CO2吸附剂，但这种直接的结构证据几乎总是在1 atm或更高压力下观察到纯组分CO2，这并不能真正代表在低分压（≤1 atm）下在其他气体存在下的实际CO2捕获和分离。 本文中，合成了一系列等网格的M0 F [Zn（Trz）（R-BDC）1/2]（FJU-40-R，R=H、NH 2、Br或OH）。其中，FJU-40-NH 2由于其分子内氢键相互作用而表现出最高的耐用性和良好的耐热性和耐水性。采用FJU-40-NH 2固体填充柱床，可有效分离CO2/N2（15：85，v/v）混合气体。在1 atm下，观察了FJU-40-NH 2在不同气氛条件下的结构，包括纯CO2、CO2/N2（15：85，v/v）和空气，发现：1）CO2负载到笼中的机制取决于CO2分压; 2）FJU-40-NH 2可以直接从空气中捕获CO2，CO2优先占据疏水笼-I，而含有氨基的亲水笼-II被H2O分子占据; 3）在低CO2分压下，三唑C-H基团而不是过去在干冰中观察到的氨基，在这里充当主要功能位点。
Direct structural observation of CO2‐loaded MOFs is helpful for revealing the specific binding interactions to allow the design of better CO2sorbents, but such direct structural evidence is almost always observed for pure‐component CO2under a pressure of 1 atm or more, which does not really represent practical CO2capture and separation under low partial pressure (≤1 atm) in the presence of other gases. Herein, a series of isoreticular MOFs [Zn(Trz)(R‐BDC)1/2] (FJU‐40‐R, R=H, NH2, Br, or OH) are synthesized. Among them, FJU‐40‐NH2exhibits the highest robustness, and good heat and water resistance, attributed to its intramolecular hydrogen‐bonding interactions. A CO2/N2(15:85, v/v) mixture can be separated efficiently through a column packed bed of FJU‐40‐NH2solid. The structures of CO2‐loaded FJU‐40‐NH2at 1 atm under various atmosphere conditions, including pure CO2, CO2/N2(15:85, v/v), and air, are observed, and it is found that: 1) the mechanism for CO2loading into the cages depends on the CO2partial pressure; 2) FJU‐40‐NH2can capture CO2directly from air, and CO2will have priority to occupy hydrophobic cage‐I, whereas hydrophilic cage‐II containing the amino group is occupied by H2O molecules; 3) the triazolate C−H groups, rather than the amino groups in past observations in dry ice, act as predominant functional sites here under low CO2partial pressure.