Water-lean absorbent for onboard carbon capture system : capture performance, reaction mechanism and energy optimization

Developing highly efficient absorbents for onboard carbon capture (OCC) systems is crucial for advancing carbon capture technology in maritime applications. A novel water-lean solution (WLS) composed of diamine 3-dimethylamino-propylamine (DMAPA) and 1-methyl-2-pyrrolidinone (NMP) has been developed in this research. The capture performance and mechanism of the DMAPA + NMP + H2O (DNH) solution were thoroughly investigated. The results showed an 118.2 % increase in average absorption rate and a 40.12 % improvement in cyclic CO2 loading capacity have been achieved using DNH solution compared to monoethanolamine (MEA) solution. NMP exhibited significant promotional effects on the capture performance in the WLS. The reaction mechanism study overcame previous computational limitations due to the lack of implicit solvent model parameters under water-lean conditions. Two proton transfer pathways under water-lean conditions were identified through quantum chemical calculations and nuclear magnetic resonance (NMR) characterization, allowing for a deeper understanding of the CO2 capture mechanism in the DNH solution. Additionally, a new method for evaluating desorption energy consumption in OCC systems under maritime conditions was developed, enabling a rapid feasibility assessment of absorbents for OCC applications. Furthermore, the energy requirement for the WLS was reduced by 82.18 % compared to the MEA, and engine exhaust energy was sufficient to maintain 100 % capture efficiency under all operating conditions. This research provides comprehensive data support and theoretical foundation for the application of WLS in OCC systems.