Carbon dioxide capture and storage by pH swing mineralization using recyclable ammonium salts and flue gas mixtures

CO 2 mineral sequestration through the employment of silicate rocks such as serpentine is an important technology for the mitigation of CO 2 emissions. Most mineral carbonation works in this study use pure CO 2 . The indirect carbonation process employed different flue gases (5, 15, 25% CO 2 ) and the presence of SOx and NOx. Also, the direct contact of CO 2 with the Mg source was compared to the indirect reaction of Mg with CO 2 as NH 4 CO 3 . The impact of variables such as temperature, solid‐liquid ration (S/L), and molar ratio of additives on carbonation rate and degree was studied. An average carbonation efficiency of about 90% was achieved at 80°C after 30 min for indirect mineral carbonation process. The carbonation efficiency decreased to 50‒60% when the process was directly employed. The carbonation efficiency obtained in the presence of 15‒25% CO 2 was very similar to that with 100% CO 2 at 140°C, while at 80°C, the carbonation efficiency in presence of flue gas (40‒55%) was much larger compared to that using pure C0 2 (10% after 3 h). SOx and NOx co‐removal efficiency was 54.4% and 18% at 140˚C and 20 bar, respectively.