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 NH 2 + , hydrogen‐bond OH, and nucleophilic Cl − . The separation of NH 3 /N 2 /H 2 , SO 2 /CO 2 /N 2 , and H 2 S/CO 2 /CH 4 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 NH 3 /N 2 /H 2 . The [DEA]Cl also exhibited the proper capacity to separate SO 2 /CO 2 /N 2 , but the capacity of [DEA]Cl for the separation of H 2 S/CO 2 /CH 4 was inferior. The theoretical calculations revealed that NH 2 + and OH worked synergistically to contribute to the ability of [DEA]Cl for excellent separation of NH 3 from NH 3 /N 2 /H 2 , with Cl − contributing to the proper separation of SO 2 from SO 2 /CO 2 /N 2 . This study provides experimental and theoretical basis for the industrial application of [DEA]Cl in the area of gas separation.