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Enhanced NH3 capture by imidazolium‐based protic ionic liquids with different anions and cation substituents

Author:
Shang, Dawei, Bai, Lu, Zeng, Shaojuan, Dong, Haifeng, Gao, Hongshuai, Zhang, Xiangping, Zhang, Suojiang
Source:
Journal of chemical technology and biotechnology 2018 v.93 no.5 pp. 1228-1236
ISSN:
0268-2575
Subject:
absorbents, absorption, ammonia, anions, cations, desorption, hydrogen, ionic liquids, liquids, nitrates, solubility, temperature, thermal degradation, vapors, viscosity
Abstract:
BACKGROUND: Ionic liquids have become potential absorbents to treat exhausted gases containing NH₃, which threatens the living environment of human beings. RESULTS: In this study, 10 kinds of protic and conventional ILs were synthesized and characterized and their densities, viscosities and thermal decomposition temperatures measured. The NH₃ solubility in ILs from the vapor liquid equilibrium (VLE) experiments revealed that the chain length of cations had little influence on the NH₃ solubility of the protic ILs because of the high NH₃ capacities in protic ILs resulting from protic hydrogen atom compared with conventional ILs. The 2‐H atom on the cation influenced the NH₃ solubility in both protic and conventional ILs with different trends as the pressure was increased. Considering the effect of anions with the same cation [Bim]⁺, the order of NH₃ solubility in protic ILs was [Bim][NTf₂] > [Bim][SCN] > [Bim][NO₃]. Dynamic absorption of NH₃ in [Eim][NTf₂] preliminarily revealed that the absorption was fast under ambient pressure and through 5 cycles of absorption and desorption, the NH₃ absorption ability remained stable. CONCLUSIONS: The relationship between the NH₃ solubility and the structures of both protic and conventional ILs was revealed, indicating the protic ILs as an alternative material for the treatment of NH₃‐containing exhaust gases. © 2017 Society of Chemical Industry
Agid:
5928086