Rational fabrication of a porous Cd-organic framework for chemical fixation of CO2 and selective sorption of p-xylene over other isomers

Highlights: • A porous Cd-organic framework is synthesized successfully. • This MOF can selective adsorption of CO₂ over CH₄ and catalyze the CO₂ cycloaddition reaction. • It exhibits different sorption abilities of benzene, toluene, m, o, p-xylene. With the rapid development of population and industry all over the world, extensive use of fossil fuels leads to carbon dioxide (CO₂) emissions with a series of thorny problems. In addition, benzene, toluene, m, o, p-xylene are commonly used organic solvents. The separation and purification is an important change in modern industrials. In this work, a two-dimensional (2D) porous metal-organic framework (MOF), [Cd₂(DCBA)·(H₂O)₃]·2DEF, H₄DCBA=4″,6′-diamino-5′,5″-bis(4-carboxyphenyl)-[1,1':3′,1'':3″,1‴-quaterphenyl]-4,4‴-dicarboxylic acid, DEF=N,N-diethylformamide), is successfully prepared by the solvothermal method. The as-synthesized sample has a rare occurrence of 5-connected mononuclear [CdO₂(CO₂)₂N] secondary building unit (SBU), which performs commendable selectivity for CO₂ over CH₄ at 273 and 298K under 1atm. In addition, the porous structure, preferable CO₂ adsorbability and open Cd(II) site can provide a platform to catalyze the CO₂ cycloaddition reaction with good recyclability. Meanwhile, this MOF exhibits different sorption abilities of benzene, toluene, m, o, p-xylene.