Reaction mechanisms of carbon dioxide capture by amino acid salt and desorption by heat or mineralization

The reaction mechanisms of potassium glycine (KG)–CO 2 absorption, thermal desorption and mineralization desorption with CaO were studied based on the contents of carbamate, bicarbonate/carbonate, and KG/protonated KG analyzed by 13 C-quantitative nuclear magnetic resonance ( 13 C qNMR). KG as the absorbent shows the CO 2 absorption efficiency up to 76% which has 57% due to the bicarbonate/carbonate formation and 43% due to the carbamate formation. Mineralization has a higher CO 2 desorption efficiency of 59% than that of thermal desorption (47%), and the results also indicate that carbamate is less stable under mineralization than under heat although both processes show the similar profiles as a function of pH value for carbamate and bicarbonate/carbonate. A new mechanism has been proposed to explain carbamate increasing with significantly decreasing bicarbonate/carbonate at the early stage of mineralization desorption while the other mechanisms reported in literatures have also been confirmed in this study.