Structural Features of Monoethanolamine Aqueous Solutions with Various Compositions: A Combined Experimental and Theoretical Study Using Vibrational Spectroscopy

In this work, we studied aqueous solutions of monoethanolamine (MEA), which are widely used to remove CO2 from flue and oil gases. This study combined experimental and theoretical methods of vibrational spectroscopy, using high-temperature infrared spectroscopy, quantum-chemical calculations of theoretical vibrational spectra, and structural electronic and energy characteristics of model structures. MEA has a propensity to form associations between various compositions and structures with water molecules, as well as those composed solely of water molecules. The structural and energy characteristics of such associates were analyzed in terms of their ability to interact and retain carbon dioxide. The influence of elevated temperatures and concentration of aqueous MEA solution on change in the structure of associates has also been investigated. An analysis of theoretical and experimental vibrational spectra allowed us to examine the IR spectra of MEA solutions, and identify the bands responsible for the formation of associates that would sorb CO2 well, but would delay its desorption from the solution.

Automated summary

This study focused on aqueous solutions of Monoethanolamine (MEA) which are commonly used for CO2 removal from flue and oil gases. By combining experimental and theoretical methods of vibrational spectroscopy, the research analyzed the structural and energy characteristics of MEA-water associates and their ability to interact and retain carbon dioxide. The influence of temperature and MEA concentration on the structural changes of the associates was also investigated. The analysis of theoretical and experimental vibrational spectra helped identify the bands responsible for the formation of CO2 sorbing associates.