Investigation of CO2 absorption and desorption performance of DETA-based phase-change solvents in alcohol-water systems

The development of efficient and low-energy solvents is critical for improving the performance and economic viability of post-combustion carbon capture processes. Conventional aqueous amine systems often suffer from high regeneration energy and limited CO 2 absorption capacity. To address these limitations, this study investigated a phase-change solvent system based on diethylenetriamine (DETA), alcohols, and water, aiming to enhance absorption performance and reduce energy consumption. Five alcohols with varied physicochemical properties-1-propanol, 1-butanol, 1-pentanol, 3-methoxypropanol, and 3-phenylpropanol were evaluated as partial water replacements to promote liquid-liquid phase separation and improve CO 2 uptake. The results show that 1-pentanol produced the highest CO 2 loading due to its stronger hydrophobicity and effective phase-separation behavior. A DETA/1-pentanol/water mass ratio of 3:4:3 achieved optimal performance, yielding a CO 2 loading of 2.417 mol/mol at 313 K. Kinetic and equilibrium studies indicated that 313 K is the preferred absorption temperature, while 353 K provides optimal desorption performance with a cycle capacity of 0.613 mol/mol and energy consumption of 2230.2 kJ. Compared to benchmark solvents such as 5 M MEA, the DETA/1-pentanol/water system demonstrated superior CO 2 absorption capacity and lower regeneration energy. These findings suggest that phase-change solvents incorporating amphiphilic alcohols offer a promising strategy for enhancing carbon capture efficiency while mitigating energy demands.