Selection of blended absorbents for CO2 capture from flue gas: CO2 solubility, corrosion and absorption rate

In the present study, trisodium phosphate (TSP) was used as a base solvent for CO2 capture, and five amines, including 2-((2-aminoethyl)amino)ethanol (AEEA), methyldiethanolamine (MDEA), piperazine (PZ), potassium sarcosinate (K-Sar) and potassium lysinate (K-Lys) were studied as potential additives to improve the absorption performance. In order to investigate and compare the performance of these blended solutions, the corrosion rate, the absorption rate and CO2 solubility were measured at a total concentration of 2.5 kmol/m3 and partial pressure of CO2 ranging from 5 to 50 kPa at 313.15 K, and were compared with monoethanolamine (MEA). The experimental results revealed that PZ as an additive in trisodium phosphate has the highest absorption rate, but the K-Lys + TSP blend solution has the highest loading capacity compared to other additives. In contrast, MDEA showed the lowest effect on the corrosion rate, CO2 solubility and absorption rate of trisodium phosphate and PZ as the additive has the highest corrosion rate. Furthermore, it was found that these blend solutions have a better performance than pure MEA. In conclusion, K-Lys is a promising additive for trisodium phosphate to apply in the separation of CO2 from gas streams.