(86i) Ionic Liquids for Absorption and Separation of Gases: An Extensive Database and a Systematic Screening Method

^a,bYongsheng Zhao, ^cRafiqul Gani, ^a,bRaja Muhammad Afzal, ^a,bSuojiang Zhang^a,b,*

^aBeijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex System, ^bInstitute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China

^cDepartment of Chemical & Biochemical Engineering, Technical University of Denmark, DK 2800 Kgs. Lyngby, Denmark

*Corresponding author: sjzhang@ipe.ac.cn

Keywords: Ionic Liquids, Gas absorption and separation, Database, Systemic screening method

In modern society, with increased focus on energy and environment, absorption and separation of gases have become a very important research topic in both academic and industrial communities. In generally, solvent absorption method is one of the most common methods in the industry. There are, however, some problems with the use of commercial absorption solvents, such as alkanolamine solutions, which require high energy consumption, associated to high economic cost, cause high VOC (volatile organic chemical) issues, and caustic byproducts. Therefore, to overcome these disadvantages, alternative and greener solvents with better separation performance need to be considered. Recently, ionic liquids (ILs) have attracted much attention because of their unique properties, especially the negligible vapour pressure and tunable properties¹. The negligible vapour pressure make ILs have low volatility and thus would not cause contamination of product and environment. The tunable property can makes us design special ILs for various purposes through proper combinations of cations and anions from a current chemical database. However, because of the tunable properties feature, there are also many possible ILs that could be synthesized. From a practical point of view, it is not feasible to measure all of the target (tunable) properties of synthesized ILs by experimental techniques, making their screening time consuming and economically costly. Therefore, it is necessary to design and select ILs using the computer aided techniques.

The aim of this study is to build a data-rich and extensive database of the Henry’s law constants of twelve gases (CO₂, NH₃, SO₂, H₂S, C₂H₂, COS, C₂H₄, CO, H₂, N₂, O₂, and CH₄) in more than ten thousand of ILs (13585 ILs), which are calculated by the COSMO-RS method. That is, more than one hundred thousand data values of the Henry’s law constants will be provided for academic and industry communities in this work. Furthermore, the objective is to develop a new, systematic, efficient and reliable screening method for selection of the appropriate IL from the 13585 ILs that are available in the database for specific absorption and separation of gases considering a set of identified tunable properties such as toxicity, bioaccumulation potential, viscosity, melting point, molality and molarity absorption capacity and separation performance. Finally, two important gases separation problems involving CO₂/CH₄ and C₂H₂/C₂H₄ will be employed as case studies to validate the developed screening method.

References:

[1] X. Zhang, X. Zhang, H. Dong, Z. Zhao, S. Zhang, Y. Huang, Carbon capture with ionic liquids: overview and progress, Energy & Environmental Science, 2012, 5: 6668-6681.

[2] R.D. Rogers, K.R. Seddon. Ionic liquids-solvents of the future? Science. 2003, 302: 792-793.