Regeneration performance and absorption/desorption mechanism of tetramethylammonium glycinate aqueous solution for carbon dioxide capture

• The regeneration performance of [N1111][Gly] solution was characterized.
• CO2 absorption into [N1111][Gly] was a reaction based on catalyzed hydrolysis.
• The CO2 desorption of [N1111][Gly] solution was the thermal decomposition of HCO3−.
• Desorption kinetics was fitted well to the Weibull equation.

Tetramethylammonium glycinate ([N1111][Gly]) aqueous solution has a good absorption ability for CO2 capture. In this paper, the desorption performance and mechanism were investigated. To explore the regeneration performance of the CO2-saturated [N1111][Gly] aqueous solution, thermal regeneration under atmospheric pressure was used by varying the regeneration temperature from 373 to 403 K and the [N1111][Gly] concentration from 5% to 30%. The effect of regeneration cycles on regeneration efficiency was also determined. The interaction between CO2 and [N1111][Gly] aqueous solution was explored by 13C Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectrometry (IR). Results showed that 15% [N1111][Gly] aqueous solution had more preferable desorption performance than the other concentrations in the range of the investigation. The regeneration efficiency of the CO2-saturated solution increased with increasing regeneration temperature from 373 to 383 K. When the temperature was above 383 K, it had little influence on the regeneration efficiency but still enhanced the desorption rate of CO2. The regeneration efficiency and the desorption rate decreased slightly during four regeneration cycles. In CO2 capture and release process, [N1111][Gly] only played a transitory role to stabilize the carbonate/bicarbonate by sequestering and providing protons. CO2 desorption kinetics could be expressed by Weibull equation: ηt/η∞=1−e−(tm/β)ηt/η∞=1−e−(tm/β).