二价铬/钼/镍空配位MOFs的CH_4/N_2吸附分离研究

CH_4/N_2 adsorption separation research of MOFs with divalent Cr/Mo/Ni unsaturated metal sites

基于金属有机骨架材料中金属空配位对气体的强吸附作用,利用具有较高活性的二价金属Cr^(2+)/Mo^(2+)/Ni^(2+)与均苯三酸(H_3BTC)配位合成了HKUST-1(Cu-BTC)同构系列材料M-BTC(M=Cr、Mo、Ni),并与Cu-BTC对比分析了该类型材料中不同金属空配位对甲烷和氮气的吸附性能。实验结果显示,此三种材料均具有较好的甲烷选择吸附性,其中含Ni^(2+)金属空位的Ni-BTC以其尤为突出的甲烷吸附热值而呈现较好的CH_4/N_2分离潜力;Cr^(2+)空配位虽具有较强活性,但是对于甲烷的选择性吸附性能却低于含Cu^(2+)空位的Cu-BTC材料。结合吸附选择性IAST计算分析得到此三种含较高活性不饱和金属空配位的MOFs材料对于甲烷选择性吸附作用能顺序为:Ni-BTC>Mo-BTC>Cu-BTC>Cr-BTC。

Based on the strong interaction energy between the coordinatively unsaturated metal sites(UMSs)and the gas molecules,M-BTC(M=Cr,Mo,Ni),isostructural with HKUST-1(Cu-BTC),were successfully synthesized via the coordination reaction of the high activity divalent metal(Cr^2+/Mo^2+/Ni^2+)and organic ligand(H3BTC),and then to gain insight into the impact of gas-metal interactions on the selective adsorption of CH4 from N2 by comparing with classical materials(Cu-BTC).The results show the good CH4 selective adsorption properties of MBTC(M=Cr,Mo,Ni)with UMSs.Among these materials,Ni-BTC with unsaturated Ni^2+sites presents the highest adsorption heat value for CH4,leading to the excellent CH4/N2 adsorption separation properties;but the Cr-BTC with high Cr^2+activity shows the lower ability for CH4/N2 separation than Cu-BTC.Combined the IAST calculation results,we verified the ability for the selective adsorption of CH4 molecules on M-BTC(M=Cr,Mo,Ni)and Cu-BTC followed as Ni-BTC>Mo-BTC>Cu-BTC>Cr-BTC.