Understanding gate adsorption behaviour of CO2 on elastic layer-structured metal-organic framework-11
Understanding gate adsorption behaviour of CO2 on elastic layer-structured metal-organic framework-11
复制标题
DOI：
10.1039/c5dt03476k
复制
发表时间：
2016-01-01
影响因子：
4
通讯作者：
Miyahara, Minoru T.
中科院分区：
文献类型：
--
作者：
Hiraide, Shotaro;Tanaka, Hideki;Miyahara, Minoru T.
我们证明了弹性层状结构的金属-有机骨架-11（ELM-11：[ Cu（BF 4）（2）（4，4 '-bipyridine）（2）]），这是一个家庭的软多孔晶体（SPC）的CO2门吸附行为，可以描述的热力学模型通过自由能分析的帮助下，吸附实验和分子模拟。ELM-11（封闭结构）在273 K抽空后的结构和CO2包封的ELM-11（开放结构）在195-298 K通过Rietveld分析使用原位同步X射线粉末衍射数据确定。然后，我们进行了巨正则蒙特卡罗（GCMC）模拟CO2吸附的开放主机框架结构的ELM-11从Rietveld分析。利用GCMC数据进行自由能分析，得到了基质三角形F基质从封闭结构到开放结构的亥姆霍兹自由能变化随温度的变化关系。我们证明了三角形F-主体与温度之间存在线性关系，从而可以分别得到主体、三角形U-主体和三角形S-主体的内能和熵变。所得三角形U-主体值与采用封闭和开放主体骨架结构的量子化学计算结果吻合良好，表明门吸附热力学模型是高度合适的。此外，我们的研究结果表明，门吸附压不仅取决于主客体相互作用和主体的内能变化，而且还取决于主体的熵变，这应该是SPC定制合成的关键因素之一。
We demonstrate that CO2 gate adsorption behaviour of elastic layer-structured metal-organic framework- 11 (ELM-11: [ Cu(BF4)(2)(4,4'-bipyridine)(2)]), which is a family of soft porous crystals (SPCs), can be described by a thermodynamic model by free energy analysis with the aid of an adsorption experiment and a molecular simulation. The structures of ELM-11 (closed structure) at 273 K after its evacuation and CO2-encapsulated ELM-11 (open structure) at 195-298 K were determined by the Rietveld analysis using in situ synchrotron X-ray powder diffraction data. We then performed grand canonical Monte Carlo (GCMC) simulations for CO2 adsorption on the open host framework structures of ELM-11 from the Rietveld analysis. The temperature dependence of the Helmholtz free energy change of host triangle F-host from the closed structure to the open structure was obtained by the free energy analysis using the GCMC data. We show that there is a linear correlation between triangle F-host and temperature, and thus, the internal energy and entropy changes of host, triangle U-host and triangle S-host, respectively, can be obtained. The obtained triangle U-host value is in good agreement with that obtained from the quantum chemical calculations using the closed and open host framework structures, which demonstrates that the thermodynamic model for gate adsorption is highly appropriate. Moreover, our result suggests that the gate adsorption pressure depends on not only the guest-host interaction and the internal energy change of host, but also the entropy change of host, which should be one of the key factors for the tailored synthesis of SPCs.