Enhancing Carbon Dioxide Desorption from Mono-ethanolamine Solutions through in-situ Mineralization and Generation of Calcium Carbonate Particles
Improving processes’ efficiency and reducing their carbon footprint is becoming more vital as the population and demand for energy increases. Today, carbon capture with amine solvents stands as the most effective and industrially applicable chemical separation technology demonstrated at a commercial scale due to their high absorption capacity and regenerability. However, aside from advantages that aqueous amine solutions offer, they suffer from the exceedingly high regeneration energy which is required to strip off the majority of absorbed CO2. The objective of this work is to improve the regeneration process of a 22 vol.% mono-ethanolamine (MEA) solution by attempting to mineralize carbon dioxide using different solid calcium precursors namely Ca(OH)2, CaCl2, and CaO at low regeneration temperatures around 80oC. The results show that adding stoichiometric amounts of Ca(OH)2, CaO and CaCl2 to balance the absorbed CO2 in MEA while heating the rich MEA solutions brought their CO2 loading to below 0.045 mol CO2/mol MEA ratio, which was much lower than 0.226 mol/mol in the case of thermal regeneration alone. In addition, the generation of solid CaCO3 particles in MEA solutions by the partial mineralization of absorbed CO2 has shown to improve both absorption and desorption kinetics. Overall, the study results proved the importance of the thermal energy in driving the mineralization reaction and thereby regenerating MEA. Moreover, the mineralization of captured CO2 could become a potential industrial improvement as it combines capturing CO2 in a thermodynamically stable form and leveraging a more chemically favored route for amine regeneration.