Surface engineering of a chromium metal-organic framework with bifunctional ionic liquids for selective CO2 adsorption: Synergistic effect between multiple active sites
Surface engineering of a chromium metal-organic framework with bifunctional ionic liquids for selective CO2 adsorption: Synergistic effect between multiple active sites
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用于选择性 CO2 吸附的双功能离子液体铬金属有机骨架的表面工程：多个活性位点之间的协同效应
DOI：
10.1016/j.jcis.2018.03.029
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发表时间：
2018-07-01
影响因子：
9.9
通讯作者：
Guan, Guofeng
中科院分区：
文献类型：
--
作者：
Chen, Chong;Feng, Nengjie;Guan, Guofeng
针对CO2捕集应用，通过合成后修饰的方法引入二乙烯三胺基离子液体，构建了一种在金属有机骨架MIL-101（Cr）中构建多吸附位点的新策略.具有多胺束缚阳离子和乙酸根阴离子的H2 O2-Ac不仅可以提供额外的结合位点，而且可以增强骨架表面对CO2的亲和力。同时，MIL-101（Cr）的高比表面积和大笼尺寸确保了IL的更好分散，从而暴露出更多的CO2吸附活性位点。此外，功能化后仍然保留了足够的自由空间，这促进了CO2的传输，并允许进入孔隙深处的Cr（III）位点。发现源自IL和MOF的多个吸附位点协同影响复合材料的CO2捕获性能。改性后的MIL-101（Cr）对CO2的吸附容量和选择性均得到显著提高。较高的等排吸附热（Q（st））证明了复合材料与CO2分子之间的相互作用较强。此外，一个可能的两步机制被提出来揭示的方式，其中CO2绑定到IL-纳入框架。尽管初始Q（st）值相对较高，但在六个循环期间，可容易地再生H2O-Ac @MIL-101（Cr），而CO2吸收几乎没有下降。(C)2018爱思唯尔公司All rights reserved.
Targeting CO2 capture application, a new strategy for building multiple adsorption sites in metal-organic framework MIL-101(Cr) was constructed through the incorporation of diethylenetriamine-based ionic liquid (DETA-Ac) via a post-synthetic modification approach. The DETA-Ac, with multi-amine-tethered cation and acetate anion, could not only provide additional binding sites, but also enhance the affinity of framework surfaces toward CO2. Simultaneously, the high surface area and large cage size of MIL-101(Cr) ensured the better dispersion of IL, thus exposing more active sites for CO2 adsorption. In addition, enough free space was still retained after functionalization, which facilitated CO2 transport and allowed the Cr(III) sites deep within the pores to be accessed. The multiple adsorption sites originating from IL and MOF were found to synergistically affect the CO2 capture performance of the composite. The adsorption capacity and selectivity of DETA-Ac@MIL-101(Cr) for CO2 were significantly improved. The higher isosteric heats of adsorption (Q(st)) evidenced the stronger interaction between the composite and CO2 molecules. Moreover, a possible two-step mechanism was proposed to reveal the manner in which CO2 bound to the IL-incorporated frameworks. Despite the relatively high initial Q(st) value, the DETA-Ac@MIL-101(Cr) could be easily regenerated with almost no drop in CO2 uptake during six cycles. (C) 2018 Elsevier Inc. All rights reserved.