Synthesis Of Imidazolyl Amino Acid Ionic Liquids With Alkoxy Side Chain And Used For CO₂ And SO₂ Capture

The acid gases produced in the fossil fuels combustion process, such as CO₂ and SO₂, have seriously threatened the ecological balance and human health. Ionic liquids have excellent physical and chemical properties. It is a new type of gas absorbent which can not only highly absorb but will not bring new pollution.In this paper, three kinds of novel imidazolyl amino acid ionic liquids with alkoxy side chain had synthesized by quaternization, [EOEOEmim][Gly], [EOEOEmmim][Ala] and [MOEOEmim][Ala]. And a group of imidazolyl amino acid ionic liquids without alkoxy side chain had synthesized as a contrast, including [bmim][Gly], [bmim][Ala], [bmmim][Gly] and [bmmim][Ala]. The structure, basic physical and chemical properties, the CO₂ and SO₂ absorption proerties of the ionic liquids were studied in detail. The specific research contents are as follows:（1）The basic properties of the product were studied, including thermal stability, density, color, electrochemical properties and so on. The results showed that all the products have excellent thermal stability, the epitaxial initial temperature are all higher than 200 ℃.（2）The properties of capture CO₂ and SO₂ at room temperature were investigated, the results show that all of the ionic liquids can capture gas at room temperature. Among them, [EOEOEmim][Gly] have the highest molar absorption, the absorption capacity for CO₂ is 0.568, and the absorption capacity for SO₂ is 3.92. In particular, the ILs with alkoxy side chain had higher molar absorption capacity for CO₂ and SO₂. Comparison of ionic liquids without alkyl side chains, molar absorption more higher 0.07 mol for CO₂ and higher 0.61 mol for SO₂. It is showed that the alkyl side chains is helpful to ionic liquids capture CO₂ and SO₂.（3）The effects of temperature on the properties of CO₂ and SO₂ were studied. The results showed that the temperature rise will decrease the absorption of the CO₂ and SO₂. But the effect of temperature on the performance of the product can be used to obtain high temperature capture and low temperature desorption. The cycle of the product capture CO₂ and SO₂ were achieved.（4）The effects of specific surface area on the properties of CO₂ and SO₂ capture were studied by using the ionic liquid in porous resin. The results showed that the increase of the specific surface area can significantly improve the CO₂ capture capacity, and significantly reduce the saturation capture time.