Liu Xiao-le, Chen Guang-Hui, Wang Xiu-Jun, Li Peng, Song Yi-Bing, Li Rui-Yan
Department of Chemistry, Shantou University, Guangdong 515063, China.
Phys Chem Chem Phys. 2017 Nov 15;19(44):29963-29974. doi: 10.1039/c7cp06141b.
The adsorption capacities of a heterometallic metal-organic framework (CPM-200-In/Mg) to VOCs (HCHO, CH, CH, CH, CH, CH, CHCl, CHCl, CHCl and CHCl) and some inorganic gas molecules (HCN, SO, NO, CO, CO, HS and NH), as well as its selectivity in ternary mixture systems of natural gas and post-combustion flue gas are theoretically explored at the grand canonical Monte Carlo (GCMC) and density functional theory (DFT) levels. It is shown that CPM-200-In/Mg is suitable for the adsorption of VOCs, particularly for HCHO (up to 0.39 g g at 298 K and 1 bar), and the adsorption capacities of some inorganic gas molecules such as SO, HS and CO match well with the sequence of their polarizability (SO > HS > CO). The large adsorption capacities of HCN and HCHO in the framework result from the strong interaction between adsorbates and metal centers, based on analyzing the radial distribution functions (RDF). Comparing CH and CH molecules interacting with CPM-200-In/Mg by VDW interaction, we speculate that the high adsorption capacities of their chlorine derivatives in the framework could be due to the existence of halogen bonding or strong electrostatic and VDW interactions. It is found that the basic groups, including -NH, -N and -OH, can effectively improve both the adsorption capacities and selectivity of CPM-200-In/Mg for harmful gases. Note that the adsorption capacity of CPM-200-In/Mg-NH (site 2) (245 cm g) for CO exceeded that of MOF-74-Mg (228 cm g) at 273 K and 1 bar and that for HCHO can reach 0.41 g g, which is almost twice that of 438-MOF and nearly 45 times of that in active carbon. Moreover, for natural gas mixtures, the decarburization and desulfurization abilities of CPM-200-In/Mg-NH (site 2) have exceeded those of the MOF-74 series, while for post-combustion flue gas mixtures, the desulfurization ability of CPM-200-In/Mg-NH (site 2) is still comparable to those of the MOF-74 series at 303 K and 4 MPa. We hope that the current theoretical study could guide experimental research in the future.
在巨正则蒙特卡罗（GCMC）和密度泛函理论（DFT）水平上，从理论上探究了一种异金属金属有机框架（CPM - 200 - In/Mg）对挥发性有机化合物（HCHO、CH₄、C₂H₄、C₂H₆、C₃H₈、C₃H₆、CH₂Cl₂、CHCl₃、CCl₄和CHCl₃）以及一些无机气体分子（HCN、SO₂、NO₂、CO₂、CO、H₂S和NH₃）的吸附容量，及其在天然气和燃烧后烟道气三元混合体系中的选择性。结果表明，CPM - 200 - In/Mg适用于挥发性有机化合物的吸附，特别是对HCHO（在298 K和1 bar下高达0.39 g/g），并且一些无机气体分子如SO₂、H₂S和CO的吸附容量与其极化率顺序（SO₂ > H₂S > CO）匹配良好。基于对径向分布函数（RDF）的分析，框架中HCN和HCHO的高吸附容量源于吸附质与金属中心之间的强相互作用。通过比较CH₄和C₂H₄分子与CPM - 200 - In/Mg的范德华相互作用，我们推测其框架中氯衍生物的高吸附容量可能归因于卤键的存在或强静电和范德华相互作用。发现包括 -NH₂、-N和 -OH在内的碱性基团可以有效提高CPM - 200 - In/Mg对有害气体的吸附容量和选择性。注意，CPM - 200 - In/Mg - NH₂（位点2）（245 cm³/g）在273 K和1 bar下对CO₂的吸附容量超过了MOF - 74 - Mg（228 cm³/g），对HCHO的吸附容量可达0.41 g/g，几乎是438 - MOF的两倍，是活性炭中吸附容量的近45倍。此外，对于天然气混合物，CPM - 200 - In/Mg - NH₂（位点2）的脱碳和脱硫能力超过了MOF - 74系列，而对于燃烧后烟道气混合物，CPM - 200 - In/Mg - NH₂（位点2）在303 K和4 MPa下的脱硫能力仍与MOF - 74系列相当。我们希望当前的理论研究能够在未来指导实验研究。
