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

Abstract 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 298 ​K under 1 ​atm. 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.