High and selective capture of low-concentration CO2 with an anion-functionalized ultramicroporous metal-organic framework

阴离子功能化超微孔MOF高效选择性捕获低浓度CO2

CO2 capture,especially under low-pressure range,is of significance to maintain long-duration human operation in confined spaces and decrease the CO2 corrosion and freezing effect for the liquefaction of natural gas.Herein,we for the first time report a novel anion-functionalized ZU-16-Co(TIFSIX-3-Co,TIFSIX=hexafluorotitanate(TiF62−),3=pyrazine),which exhibits one-dimensional pore channels decorated by abundant F atoms,for efficient CO2 capture at a concentration around 400–10,000 ppm.Among its isostructural MFSIX-3(M=Si,Ti,Ge)family materials,ZU-16-Co with fine-tuned pore size of 3.62Åexhibits the highest CO2 uptake at 0.01 bar(10,000 ppm)and 1 bar(2.63 and 2.87 mmol g−,respectively).The high CO2 capture ability of ZU-16-Co originates from the fine-tuned pore dimensions with strong F⋯C=O host-guest interactions and relatively large pore volumes coming from its longer coordinated Ti-F-Co distance(3.9Å)in c direction.The excellent carbon trapping performance was further verified by dynamic breakthrough tests for CO2/N2(1/99 and 15/85)and CO2/CH4(50/50)mixtures.The adsorption and separation performances,resulting from the fine-tuned pore system with periodic arrays of exposed functionalities,demonstrate that ultramicroporous ZU-16-Co can be a promising adsorbent for low-concentration carbon capture.

CO2捕获,尤其低浓度CO2捕获,对人类在限域空间中长时间工作、降低天然气液化过程中CO2腐蚀及冻结效应极为重要.本文首次报道了一种具有一维孔道的ZU-16-Co(TIFSIX-3-Co)材料,该材料孔道中含大量电负性F原子,可实现400–10,000 ppm浓度下CO2的高效捕获.相比同构材料,孔径为3.62?的ZU-16-Co在0.01和1.0 bar表现出最高的吸附量,分别为2.63和2.87 mmol g^-1.模拟研究表明,ZU-16-Co具有优异的CO2捕获性能是由于其精准调控的孔道与CO2较强的主客体相互作用(F···C=O)及相对较大的孔容.此外,动态混合气(1/99和15/85 CO2/N2,50/50 CO2/CH4)固定床穿透实验也表明ZU-16-Co具有优良的CO2捕获性能.精准调控的孔化学尺度及周期性排布的电负性功能位点带来的良好的CO2捕获、分离性能使得超微孔ZU-16-Co成为极具前景的低浓度CO2吸附剂.