Phase Splitting Rules of the Primary/Secondary Amine–Tertiary Amine Systems: Experimental Rapid Screening and Corrected Quasi-Activity Coefficient Model
Xingyu Li, Yuheng Wang, Houfang Lu, Shan Zhong, Changjun Liu, Lei Song, Siyang Tang, Bin Liang
Abstract
Several phase splitting systems have shown potential in reducing regeneration energy consumption for large-scale CO2 capture in the last decade. The development of new phase splitting systems currently depends on experimental screening. In this work, 90 sets of primary/secondary amine–tertiary amine anhydrous systems and 160 sets of primary/secondary amine–tertiary amine–water systems were used to investigate the phase splitting rules at the molecular level. The results show that the phase splitting behavior of the anhydrous system is directly affected by the carbamate solubility in the tertiary amine. The potential phase splitting system has a tertiary amine with proper lipophilicity. Among the aqueous systems, two different phase splitting zones were recognized: the salting-out effect zone with a lower amine log P and the cosolvent effect zone with a higher amine log P. Several thermotropic phase splitting systems are located at the edge of these two zones. The tertiary amine with more tert-amine groups and less hydroxyl groups would facilitate phase splitting. The primary/secondary amine with hydroxyl groups on the straight chain would facilitate phase splitting. A new parameter describing the primary amine/secondary amine as a nonelectrolyte is introduced to develop a new quasi-activity coefficient of the chemical–chemical aqueous system. This quasi-activity coefficient is applicable to the mono- or polyamine systems with different material ratios.