A quantum chemistry study for 1-ethyl-3-Methylimidazolium ion liquids with aprotic heterocyclic anions applied to carbon dioxide absorption

作者：Hu, Jianqin; Chen, Litao^*; Shi, Meiqin; Zhang, Cheng

来源：Fluid Phase Equilibria, 2018, 459: 208-218.

DOI：10.1016/j.fluid.2017.12.016

• Ionic liquids
• CO2 absorption
• Aprotic heterocyclic anions
• N-heterocyclic carbenes

Flue gas is largely responsible for acid rain and global warming. A special class of imidazolium-based ionic liquids (ILs) has been given a great deal of attention as holding a high absorptivity for the acid gas component, such as CO2. We simulate a class of novel ionic liquids (ILs) formed between the 1-ethyl-3-methylimidazolium cation ([emim](+)) and the aprotic heterocyclic anions (AHA), and present a molecular-level description of the interactions of ILs with CO2. The covalent bonds are found between anions and CO2 in the calculated minimum energy structures at B3LYP/6-311++G (d,p) level. And also the basicity of anion is found to have a promotional effect on the solubility of CO2 in ILs. The energy barriers of proton transfer show that [emim][Ind], [emim][4-Triaz] and [emim][3-Triaz] will produce imidazolium carbonates during the proton transfer process because of their high basicities. Both [emim] [Tetz] and [emim][Bentri], however, can not prompt the formation of the intermolecular carbene because their basicities are too weak to do so. This implies that the formation of N -heterocyclic carbine complexes can be effectively tuned by varying the basifies of counteractions. Additionally, the infrared spectra are presented to investigate the ion pair vibration characteristics. And the further natural bond orbital (NBO) method is applied to reveal the mechanism of hydrogen bonding interactions.

• 出版日期2018-3-15
• 单位浙江工业大学