In this work, in situ ATR-FTIR spectroscopy was used to study the interaction of CO₂ and a series of 1-alkyl-3-methylimidazolium tetrafluoroborate С_nMIMBF₄ (n = 2, 4, 6, 8, 10) ionic liquids. A detailed analysis of the infrared spectra acquired from ionic liquids and sorbed СО₂ was performed as ionic liquids with different the alkyl chain lengths were subjected to changing pressures of СО₂ and temperature. With a longer alkyl chain length, an increase in the shift of the CH stretching vibrations bands of alkyl groups and BF stretching vibrations of BF₄⁻ anions is observed during CO₂ sorption. This indicates the disaggregation of alkyl chains and anions. There is a correlation with the position of the wavenumber of the ν₃ asymmetric stretching CO₂ band and the length of the alkyl chain. It was found that some of the CO₂ adsorbed by ionic liquids does not interact with the ionic liquid but is “free” in the bulk of the alkyl chains. For the first time, ATR-FTIR spectroscopy was used to determine the thermodynamic parameters of CO₂ sorption in ionic liquids. It was demonstrated that the values of enthalpy and entropy obtained by analysis of the ATR-FTIR spectra are consistent the data obtained by other methods. A correlation was found between the enthalpy of sorption of CO₂ and the wavenumber of the ν₃ band. This opens up the possibility of using CO₂ as an IR-sensitive probe molecule to characterize the acid-base properties of ionic liquids and determine the enthalpy of CO₂ sorption.

在这项工作中，原位ATR-FTIR光谱学用于研究CO的相互作用₂和一系列的1-烷基-3-甲基咪唑鎓四氟硼酸盐С _Ñ MIMBF ₄（Ñ  = 2,4，6，8，10）的离子液体。从离子液体中获取的红外光谱的详细分析和吸附СО ₂具有不同的烷基链长进行变更的СО压力离子液体进行₂和温度。具有较长烷基链的长度，增加了CH伸缩烷基和BF的BF伸缩振动的振动频带的移位₄ ^-阴离子是CO过程中观察到₂吸附。这表明烷基链和阴离子的分解。存在与ν的波数的位置的相关性₃反对称伸缩CO ₂频带和烷基链的长度。发现离子液体吸附的某些CO ₂不与离子液体相互作用，但在大部分烷基链中“游离”。首次使用ATR-FTIR光谱法确定离子液体中CO ₂吸附的热力学参数。结果表明，通过ATR-FTIR光谱分析获得的焓和熵值与通过其他方法获得的数据一致。发现CO ₂的吸附焓之间存在相关性和ν的波数₃频带。这开辟了使用CO ₂作为IR敏感探针分子来表征离子液体的酸碱性质并确定CO ₂吸附焓的可能性。