Infrared spectroscopic and physico-chemical analysis of carbon dioxide-rich and -lean 30 wt% monoethanolamine

Abstract

Carbon dioxide (CO2) is the most significant greenhouse gas, contributing 44% of global warming using coal combustion for electricity generation. The major goal is to reduce carbon dioxide emissions by using the carbon dioxide capture and storage (CCS) technique. Among various techniques, amine-based post-combustion carbon dioxide capture plays a critical role in CCS technology. Monoethanolamine (MEA) acts as a benchmarking solvent in the CCS process owing to its high absorption capacity, lower cost and high rate of reaction. The present investigation used 30 wt% MEA and animised flue gas (15 vol% carbon dioxide and resting nitrogen (N2) gas) at 0.5 pound/square inch (3.45 kPa) inlet pressure for carbon dioxide absorption followed by 1 h solvent regeneration (direct and indirect heating). Furthermore, measurements of physico-chemical properties such as pH, carbon dioxide loading, density, viscosity, alkalinity and surface tension and Fourier transform infrared (FTIR) spectroscopic analysis of unloaded, carbon dioxide-loaded and regenerated samples were carried out. During carbon dioxide absorption, a rich loading of 7.775 mol/kg was obtained, whereas after regeneration, lean loadings of 3.099 and 3.937 mol/kg were achieved. FTIR analysis of the regenerated sample reconfirmed carbamate and bicarbonate presence, indicating that the sample required further regeneration. An increase in density, viscosity and surface tension was observed during carbon dioxide loading due to stronger intermolecular forces between the solvent and carbon dioxide molecules, and a decrease was observed during solvent regeneration due to carbon dioxide stripping.