CO2 capture solvent selection by combined absorption–desorption analysis

A method was developed for selection of promising solvents based on CO2 absorption experiments at 40 °C and 9.5 kPa CO2 partial pressure followed by desorption of the same solvents at 80 °C down to 1.0 kPa CO2 partial pressure. Experiments conducted on 13 solvent systems under atmospheric conditions revealed the solvents absorption and desorption characteristics and these were compared with 1.0 M, 2.5 M, 5.0 M and 10.0 M MEA. Results showed that absorption or stripping data alone were not sufficient in making robust solvent selection decisions, and that combined data analysis was necessary. 1.0 M tetraethylenepentamine (TEPA) and 5.0 M MEA showed the best performance in terms of absorption rate. 1.5 M Bis-(3-dimethylaminopropyl) amine (TMBPA) was easy to desorb, has high absorption capacity; and when promoted it showed the best performance in terms of CO2 carrying capacity. At the test conditions, 1.5 M TMBPA promoted with 1.0 M PZ showed the best potential for efficient CO2 removal at reduced cost of all systems tested. Its cyclic capacity in mol CO2/mol amine was found to be 70% higher than that of 5 M MEA.

Research highlights
► Rapid screening experiments was conducted on promising solvents for CO2 capture.
► We developed a method for identifying most promising solvents after experiments.
► TMBPA promoted with Piperazine has best potential for CO2 capture at reduced cost.