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Ionic Liquids: Properties and Applications

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Front. Chem. | doi: 10.3389/fchem.2018.00658

CO2 Absorption by DBU-Based Protic Ionic Liquids: Basicity of Anion Dictates the Absorption Capacity and Mechanism

 Feixiang Gao1,  Zhen Wang2, Jin-Pei Cheng1 and  Pengju Ji1*
  • 1Tsinghua University, China
  • 2School of Chemical and Environmental Engineering, Anyang Institute of Technology, China

PILs are promising solvent systems for CO2 absorption and transformations. Although previously tremendous work has been paid to synthesize functionalized PILs to achieve a high-performance absorption, the underlying mechanisms are far less investigated and still not clear. In this work, a series of DBU-based PILs, i.e., [DBUH][X], with anions of various basicities were synthesized. The basicities of the anions were accurately measured in [DBUH][OTf] or extrapolated from the known linear correlations. The apparent kinetics as well as the capacities for CO2 absorption in these PILs were studied systematically. The results show that the absorption rate and capacity in [DBUH][X] are in proportional to the basicity of PIL, i.e., a more basic PIL leads to a faster absorption rate and a higher absorption capacity. In addition, the spectroscopic evidences and correlation analysis indicate that the capacity and mechanism of CO2 absorption in [DBUH][X] are essentially dictated by the basicities of anions of these PILs.

Keywords: Protic ionic liquids, Basicity, CO2 absorption, Linear correlation, absorption mechanism and capacity

Received: 18 Sep 2018; Accepted: 18 Dec 2018.

Edited by:

Jason B. Harper, University of New South Wales, Australia

Reviewed by:

Ekaterina Pas, Monash University, Australia
Tamar L. Greaves, RMIT University, Australia  

Copyright: © 2018 Gao, Wang, Cheng and Ji. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Pengju Ji, Tsinghua University, Beijing, China,