Direct Separation of para-Xylene from Xylene Isomers by a Zinc Bipyrazolate Framework

Separation of xylene isomers is an important challenge for the chemical industry. Here, we report a new zinc bipyrazolate framework MAF-70 for the separation of xylene isomers, which contains square pore channels of 8.7× 8.7 Ų. MAF-70 exhibits a rare adsorption preference of ortho-xylene (oX) > meta-xylene (mX) > para-xylene (pX) with high selectivity for oX/pX and mX/pX (12.0 and 4.0, respectively), facilitating direct purification of pX (99.1+% purity) from a xylenes mixture, which is validated by column separation experiments. Modeling study indicates that the restricted diffusion of pX accounts for such separation.