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

CO2 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 fl ue 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 effi ciency of about 90% was achieved at 80 degrees C after 30 min for indirect mineral carbonation process. The carbonation effi ciency decreased to 50-60% when the process was directly employed. The carbonation effi ciency obtained in the presence of 15-25% CO2 was very similar to that with 100% CO2 at 140 degrees C, while at 80 degrees C, the carbonation effi ciency in presence of fl ue gas (40-55%) was much larger compared to that using pure CO2 (10% after 3 h). SOx and NOx co-removal effi ciency was 54.4% and 18% at 140 degrees C and 20 bar, respectively. (C) 2015 Society of Chemical Industry and John Wiley & Sons, Ltd