Zeolitic imidazolate frameworks-based porous liquids with low viscosity for CO2 and toluene uptakes

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2021-08, Vol.417, p.129239, Article 129239
• Main Authors: Li, Xiaoqian, Wang, Dechao, He, Zhongjie, Su, Fangfang, Zhang, Nan, Xin, Yangyang, Wang, Hongni, Tian, Xiaolu, Zheng, Yaping, Yao, Dongdong, Li, Mingtao
• Format: Article
• Language: English
• Subjects: CO2 and toluene uptake; Dicationic ionic liquids; Low melting points; Low viscosity; Porous liquids
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2021.129239

•[C6BIm2][NTf2]2 as solvents to construct ZIFs-based PLs with low viscosity.•The viscosity of ZIFs-PLs is decreased by 20 times than that of the reported PLs.•The permanent porosity of ZIF-PLs was confirmed by molecular simulation.•ZIF-67-PLs-10 achieved higher CO2 and toluene adsorption capacity than DILs.•ZIFs-PLs are expected to be gas capture and selective separate. Porous liquids (PLs) as a novel class of materials combine the permanent porosity of microporous solids, the rapid mass transfer of liquids, and fluidity, thus exhibiting extraordinary promise for gas capture and separation. However, the practical application of PLs was severely restricted by their undesirable relative high viscosity and melting temperature. In this work, the symmetric dicationic ionic liquids [C6BIm2][NTf2]2 was synthesized as a steric hindrance solvent to construct a type of low viscosity zeolitic imidazolate frameworks (ZIFs)-based PLs. Specifically, the ZIF-67-PLs-2 (i.e., ZIF-67 loading of 2.0% in PLs) presented a low viscosity with 543.4 mPa·S at 25 °C, which was about 20 times lower than that of type III PLs reported previously. Meanwhile, ZIF-67-PLs showed long-term stability even over 180 days and broke the fluidity limitation down to −64 °C, broadening the work conditions. Moreover, ZIF-67-PLs-10 (i.e., ZIF-67 loading of 10.0% in PLs) achieved 55 times CO2 and 7 times toluene adsorption capacity more than those of the corresponding pure DILs, respectively. Remarkably, the fascinating features of ZIF-67-PLs including lower viscosity, wide liquid range and higher adsorption pave a new way for the optimal design of novel PLs towards gas uptake and separation.