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

Abstract

AbstractCO2 mineral sequestration through the employment of silicate rocks such as serpentine is an important technology for the mitigation of CO2 emissions. Most mineral carbonation works in this study use pure CO2. The indirect carbonation process employed different flue gases (5, 15, 25% CO2) and the presence of SOx and NOx. Also, the direct contact of CO2 with the Mg source was compared to the indirect reaction of Mg with CO2 as NH4CO3. 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% CO2 was very similar to that with 100% CO2 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 C02 (10% after 3 h). SOx and NOx co‐removal efficiency was 54.4% and 18% at 140˚C and 20 bar, respectively.