State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
J Phys Chem B. 2013 Feb 28;117(8):2482-6. doi: 10.1021/jp311707e. Epub 2013 Feb 12.
As a kind of novel and efficient material, ionic liquids (ILs) are used for capture of acidic gases including SO2 and CO2 from flue gas. Due to very low content of acidic gases in flue gas, it is important to find functional ILs to absorb the acidic gases. However, up to now, there is no criterion to distinguish if the ILs are functional or not before use, which greatly influences the design of functional ILs. In this work, a series of ILs were synthesized and used to determine functional or normal ILs for the capture of acidic gases. It has been found that the pKa of organic acids forming the anion of ILs can be used to differentiate functional ILs from normal ILs for the capture of acidic gases from flue gas. If the pKa of an organic acid is larger than that of sulfurous acid (or carbonic acid), the ILs formed by the organic acid can be called functional ILs for SO2 (or CO2) capture, and it can have a high absorption capacity of SO2 (or CO2) with low SO2 (or CO2) concentrations. If not, the IL is just a normal IL. The pKa of organic acids can also be used to explain the absorption mechanism and guide the synthesis of functional ILs.
作为一种新型高效的材料，离子液体 (ILs) 被用于从烟道气中捕获包括 SO2 和 CO2 在内的酸性气体。由于烟道气中酸性气体的含量非常低，因此找到能够吸收酸性气体的功能性 ILs 非常重要。然而，到目前为止，在使用之前，没有标准来区分 ILs 是否具有功能性，这极大地影响了功能性 ILs 的设计。在这项工作中，合成了一系列 ILs，并用于确定用于捕获酸性气体的功能性或普通 ILs。已经发现，形成 IL 阴离子的有机酸的 pKa 可用于将用于从烟道气中捕获酸性气体的功能性 ILs 与普通 ILs 区分开来。如果一种有机酸的 pKa 大于亚硫酸（或碳酸）的 pKa，则由该有机酸形成的 ILs 可称为用于 SO2（或 CO2）捕获的功能性 ILs，并且可以在 SO2（或 CO2）浓度较低的情况下具有高的 SO2（或 CO2）吸收能力。否则，该 IL 只是普通 IL。有机酸的 pKa 还可以用来解释吸收机制并指导功能性 ILs 的合成。
