Chemical Research in Chinese Universities ›› 2021, Vol. 37 ›› Issue (3): 679-685.doi: 10.1007/s40242-021-1064-z

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Tailoring Pore Structure and Morphologies in Covalent Organic Frameworks for Xe/Kr Capture and Separation

YUAN Mengjia1, WANG Xia1, CHEN Long1, ZHANG Mingxing1, HE Linwei1, MA Fuyin1, LIU Wei2, WANG Shuao1   

  1. 1. State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences(RAD-X) and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, P. R. China;
    2. School of Environment and Material Engineering, Yantai University, Yantai 264005, P. R. China
  • Received:2021-02-19 Revised:2021-03-15 Online:2021-06-01 Published:2021-03-16
  • Contact: MA Fuyin, WANG Shuao E-mail:mafuyin@suda.edu.cn;shuaowang@suda.edu.cn
  • Supported by:
    This work was supported by the National Natural Science Foundation of China(Nos.21906112, 21790374).

Abstract: As a rising star among porous solid materials, covalent organic frameworks(COFs) with excellent properties including but not limit to facilely controllable structure, high porosity, and multi-chemical functionality represent significant potential for efficient 127Xe/85Kr capture and separation. In this study, through tuning the length of the organic ligands, two-dimensional(2D) COF mate-rials with identical connection group but different pore properties, denoted as ATFG-COF and TpPa-COF with AA-stacking model and TpBD-COF with AB-stacking model were synthesized and tested for Kr and Xe adsorption for the first time. Adsorption measurements indicate that the narrower pore apertures and higher porosity are conducive for COF materials to capture Xe and Kr. Furthermore, the Henry's constant, isosteric heat of adsorption(Qst), and ideal adsorbed solution theory(IAST) selectivity of ATFG-COF, the pore size of which is closest to the kinetic diameter of the Xe atom(0.41 nm) among 2D COF materials, were carried out based on the single component sorption isotherms. The results illustrate that the high isosteric heat values of Xe/Kr adsorption on ATFG-COF are 25 and 16 kJ/mol at room temperature, respectively. Henry's law predicts that the selectivity factor of Xe to Kr is 6.07, consistent with the adsorption selectivity(ca. 6) calculated based on the IAST.

Key words: Covalent organic framework, Kr/Xe capture, Kr/Xe separation, Pore size, Pore volume