Evaluating diethanolammonium chloride as liquid solvent for gas separation from experiments and theoretical calculations

Abstract

This study explored diethanolammonium chloride ([DEA]Cl) as a potential ionic liquid from low‐cost and commercial ones for gas separation. There are three kinds of functional sites in [DEA]Cl: acidic NH2+, hydrogen‐bond OH, and nucleophilic Cl−. The separation of NH3/N2/H2, SO2/CO2/N2, and H2S/CO2/CH4 was considered, because the three mixtures are extensively involved in many industrial processes. The experimental results demonstrated that [DEA]Cl exhibited excellent ability to separate the mixture of NH3/N2/H2. The [DEA]Cl also exhibited the proper capacity to separate SO2/CO2/N2, but the capacity of [DEA]Cl for the separation of H2S/CO2/CH4 was inferior. The theoretical calculations revealed that NH2+ and OH worked synergistically to contribute to the ability of [DEA]Cl for excellent separation of NH3 from NH3/N2/H2, with Cl− contributing to the proper separation of SO2 from SO2/CO2/N2. This study provides experimental and theoretical basis for the industrial application of [DEA]Cl in the area of gas separation.