Compared with traditional zeolite adsorbents, metal organic frameworks (MOFs) have shown unparalleled advantages and potential in the field of adsorption and separation due to their structural flexibility and tunability.One of the most promising applications for MOFs is in their use as xylene adsorbents. Xylene isomers, including para-xylene (p-xylene), meta-xylene (m-xylene), and ortho-xylene (o-xylene), have different applications and values in the chemical industry.

In recent years, the research team led by Prof.XU yunpengand Prof. LIU zhongminhas been committed to the development of high-efficiency MOFs adsorbents for the separation of xylene isomers.Progress has been made in the synthesis research and the exploration of the adsorption mechanism of the fluorinated anion hybrid MOFs material that preferentially adsorb o-xylene (Chem.-Eur.J.)and the high crystallinity MIL-125 material that preferentially adsorbs p-xylene (Chin.J.Catal.). Recently, the research team has made new progress in the study of MOFsadsorption and separation of xylene isomers, and successfully prepared a type of cobalt-based pillar layered MOF-Co(aip)(bpy)_0.5that exhibits ultra-high competitive adsorption selectivity in the separation of xylene isomers.

It was found that Co(aip)(bpy)_0.5exhibited asignificant para-selectivity in liquid-phase competitive adsorption of xylene isomers, and the competitive separation factors reached as high as 30 for p-xylene versus m-xylene and 16 for p-xylene versus o-xylene. Desorption experiments further confirmed the preferential adsorption of p-xylene on the adsorbent. Molecular simulations and calculations revealed that the order of interaction strengths for xylene molecules and the adsorbent framework was p-xylene >> o-xylene ~ m-xylene, which illustrated the selective adsorption phenomena arising from the mechanism for microscopic interactions.This work broadens the application ofpillar-layerMOF materials in the field of xylene isomers adsorption and separation.

Related research results, entitled "Efficient Separation of Xylene Isomers by a Pillar-Layer Metal-Organic Framework", were recently published onACS Appl. Mater. Interfaces. This research was supported by the National Natural Science Foundation of China and the Talent Program for Revitalization of Liaoning Province.(Text by YANGliping)

Efficient Separation of Xylene Isomers by a Pillar-Layer Metal-Organic Framework.Liping Yang, Hanbang Liu, Danhua Yuan, Jiacheng Xing,Yunpeng Xu*, Zhongmin Liu.ACS Applied Materials & Interfaces, DOI: 10.1021/acsami.1c10462, 2021.