(408j) Gas Capture by Ionic liquids

Authors: 
Zhang, X., Chinese Academy of Sciences
Zhang, S., Beijing Key Laboratory of Ionic Liquids Clean Process,CAS Key Labroratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences
With the rapid development of the global industrialization process, a large number of gases, such as CO2, SO2, NH3 and H2S, have been produced. Among of them, CO2 and SO2 have caused air pollution problems, resulting in a serious harm to the environment and human health. On the other hand, CO2 and SO2 are also important source for synthesizing chemicals. Recently, ionic liquids (ILs) have been regarded as one of the most promising alternative solvents for capturing CO2 or SO2 due to their special physicochemical properties, such as negligible vapor pressure and designable character. For example, it was found that N-butylpyridinium thiocyanate ([C4Py][SCN]) can absorb 0.841 gSO2/g IL at 293 K and 0.10 MPa1.

In this work, the mechanism of CO2/SO2 absorption in different kinds of ILs were systemically studied by molecular simulations. The microscopic structure, interaction energy and dynamic properties of the mixtures of ILs and CO2/SO2 were investigated. The results of interaction energy and fractional free volume of ILs showed that unlike non-polar gas CO2, the interaction energy of cation-anion and free volume do not play a dominant role in SO2 absorption. The solvation of SO2 in ILs is controlled by enthalpy. Both the cations and anions play an important role in SO2 solubility. Based on the above studies, a serial of ILs were synthesized for capturing CO2/SO2. Moreover, the energy and economic analysis of whole process of CO2 capture with ILs were simulated. It was found that the IL process saved about 15% regeneration heat energy consumption and 11.5% total capture cost compared to the MEA process.

Acknowledgment

This work was supported by the National Natural Scientific Fund of China 51674234.

Reference

  1. J. Zeng, H. S. Gao, X. C. Zhang, H. F. Dong, X. P. Zhang, S. J. Zhang, Chem. Eng. J, 2014, 251, 248-256.