TY - JOUR

T1 - Interactions of C2H6 and C2H4 with the homologous series [CnMIM][BF4] ionic liquids at high pressure studied by in situ ATR-FTIR spectroscopy

AU - Kovalev, E. P.

AU - Shalygin, A. S.

AU - Shubin, A. A.

AU - Kozhevnikov, I. V.

AU - Prikhod'ko, S. A.

AU - Adonin, N. Yu

AU - Kazarian, S. G.

AU - Martyanov, O. N.

N1 - Funding Information: This work was supported by Ministry of Science and Higher Education of the Russian Federation , grant number 075-15-2019-1876 and within the governmental order for Boreskov Institute of Catalysis , project АААА-А21- 121011390053-4 . Publisher Copyright: © 2021 Elsevier B.V.

PY - 2022/2/15

Y1 - 2022/2/15

N2 - It is believed that ionic liquids (IL) can be a promising sorbent for separating a mixture of olefins and paraffins due to their unique properties. Understanding the interaction between IL and sorbed gases plays a key role in the development of selective separation processes. In this work, for the first time, in situ ATR-FTIR spectroscopy was used to study the interaction of light hydrocarbons (C2H6, C2H4) and a series of 1-alkyl-3-methylimidazolium tetrafluoroborate [CnMIM][BF4] (n = 2, 4, 6, 8, 10, 12) ILs. The spectra of liquid ethane and ethylene were obtained, as well as the spectra of IL under the pressure of hydrocarbons. An increase in the length of the alkyl chain of the cation leads to an increase in the solubility of both ethane and ethylene. The data obtained demonstrate a significant interaction between ethylene and IL, which leads to a greater dissolution of ethylene relative to ethane. A blue-shift of the bands of sorbed ethylene relative to liquid ethylene is observed. At the same time, an increase in the length of the alkyl chain of the cation leads to a shift in the wavenumber of sorbed ethylene towards lower wavenumbers, which is the result of a decrease in the interaction between IL and ethylene and the dissolution of ethylene in the free volume of IL. In addition, it has been found that it is possible for two hydrogen atoms of ethylene to interact to form a hydrogen bond between the anion of the IL and ethylene.

AB - It is believed that ionic liquids (IL) can be a promising sorbent for separating a mixture of olefins and paraffins due to their unique properties. Understanding the interaction between IL and sorbed gases plays a key role in the development of selective separation processes. In this work, for the first time, in situ ATR-FTIR spectroscopy was used to study the interaction of light hydrocarbons (C2H6, C2H4) and a series of 1-alkyl-3-methylimidazolium tetrafluoroborate [CnMIM][BF4] (n = 2, 4, 6, 8, 10, 12) ILs. The spectra of liquid ethane and ethylene were obtained, as well as the spectra of IL under the pressure of hydrocarbons. An increase in the length of the alkyl chain of the cation leads to an increase in the solubility of both ethane and ethylene. The data obtained demonstrate a significant interaction between ethylene and IL, which leads to a greater dissolution of ethylene relative to ethane. A blue-shift of the bands of sorbed ethylene relative to liquid ethylene is observed. At the same time, an increase in the length of the alkyl chain of the cation leads to a shift in the wavenumber of sorbed ethylene towards lower wavenumbers, which is the result of a decrease in the interaction between IL and ethylene and the dissolution of ethylene in the free volume of IL. In addition, it has been found that it is possible for two hydrogen atoms of ethylene to interact to form a hydrogen bond between the anion of the IL and ethylene.

KW - ATR-FTIR spectroscopy

KW - Ethane

KW - Ethylene

KW - Homologous series

KW - Ionic liquids

KW - Sorption

UR - http://www.scopus.com/inward/record.url?scp=85119470399&partnerID=8YFLogxK

U2 - 10.1016/j.molliq.2021.118082

DO - 10.1016/j.molliq.2021.118082

M3 - Article

AN - SCOPUS:85119470399

VL - 348

JO - Journal of Molecular Liquids

JF - Journal of Molecular Liquids

SN - 0167-7322

M1 - 118082

ER -