On the mechanisms of CO2 absorption and desorption with phase transitional solvents. (January 2017)

• Record Type: Journal Article
• Authors: Ye, Qing; Zhu, Lingyang; Wang, Xinlei; Lu, Yongqi
• Is Part Of: International journal of greenhouse gas control. Volume 56(2017)
• Page Start: 278
• Page End: 288
• Publication Date: 2017-01
• Subjects: CO2 capture -- Absorption -- Desorption -- Phase transition -- NMR spectroscopy -- Solvent; Greenhouse gases -- Environmental aspects -- Periodicals; Air -- Purification -- Technological innovations -- Periodicals; Gaz à effet de serre -- Périodiques; Gaz à effet de serre -- Réduction -- Périodiques; Air -- Purification -- Technological innovations; Greenhouse gases -- Environmental aspects; Periodicals; 363.73874605
• DOI: 10.1016/j.ijggc.2016.11.027
• Languages: English
• ISSNs: 1750-5836

Abstract

Graphical abstract: Highlights: Solvent phase transitions achieved in both CO2 absorption and desorption processes. Species formed during both CO2 absorption and desorption quantified by NMR. Detailed mechanisms of CO2 absorption and desorption reactions elucidated. Biphasic solvents outperformed MEA in CO2 capacity and desorption pressure. Abstract: Two phase transitional aqueous solvent blends consisting of diethylenetriamine (DETA) and N, N, N′, N′, N″ -pentamethyldiethylenetriamine (PMDETA) were experimentally investigated to determine their CO2 absorption, phase transition, and desorption performance. Both solvents revealed higher CO2 loading capacities and desorption pressures than a 5 M monoethanolamine solution under comparable conditions. The evolution of solvent species during the CO2 absorption and desorption processes was determined quantitatively by using 1 H, 13 C, and 2-D nuclear magnetic resonance spectroscopic techniques. Mechanisms of the CO2 absorption and desorption reactions were proposed based on the speciation analysis. Carbon dioxide absorption occurred as the carbamates and dicarbamates of DETA were formed, followed by CO2 hydration promoted by proton exchange with PMDETA. Desorption of CO2 could generally be described as a reverse absorption process, but it was also coupled with a dual phase transition.