Selective Separation of C₈ Aromatics by an Interpenetrating Metal-Organic Framework Material

O-xylene (OX) is an important chemical raw material, but it is often produced in mixtures with other C₈ aromatics. Similar physicochemical properties of the C₈ isomers make their separation and purification very difficult and energy intensive. There is an unmet need for an adsorbent that would be effective for the separation of OX from the other C₈ isomers. This work reports a three-dimensional interpenetrated metal-organic framework, SYUCT-110, that interacts with each of the single-component C₈ isomers to form. The selectivity of C₈ aromatic hydrocarbons was determined through liquid-phase batch uptake experiments. The results revealed that the selectivity order was OX > PX > MX > ethylbenzene (EB). The selectivity values were found to be 2.63, 1.58, 5.51, 3.71, 1.86, and 3.02 for OX/MX, OX/PX, OX/EB, PX/MX, MX/EB, and PX/EB, respectively. The adsorption capacity of OX was 71 mg/g. Grand Canonical Monte Carlo simulations were used to study the C₈ adsorption sites, revealing that π···π interactions are the main reason for the observed adsorption selectivity. The adsorption energy calculation results also verified the selectivity of SYUCT-110 for the synthesis of OX.