Monitoring of Chemical Speciation of DEA – CO₂ – Water System by Raman Spectroscopy

Carbon dioxide separation has gained immense importance since its detrimental effects towards our environment has been realized. Commercially, CO2 has been captured by absorption in alkanolamines such as diethanolamine (DEA), since many years. The thermodynamics and kinetics of the process is a key factor towards its efficiency and significantly depends on its qualitative and quantitative speciation. In this work, the analysis of speciation for CO2 loaded aqueous DEA has been performed by Raman spectroscopy. Experimentally determined CO2 loading data and modified Kent Eisenberg equation was used to quantify the chemical species present. The speciation results were fitted with the respective characteristic Raman peaks of (CO3-, HCO3-, DEACOO-, DEA, DEAH+, CO2) by Principal Component Regression (PCR). The fitted results showed good agreement with thermodynamically predicted chemical species.