Integrated\nAbsorption and Mineralization to Carbon\nCapture from Marine Engine Exhaust Gases and Coproduce Magnesium Carbonate

The issue of air pollution caused by fossil-fuel-powered\nships\nhas been adequately addressed, yet the challenges posed by greenhouse\ngas emissions still require further attention. Onboard carbon capture\nand storage technology represents effective means of reducing CO<sub>2</sub> emission from ships. However, the general amine-based solvent\nprocess demands significant power input, whereas carbon mineralization\nprocesses were slowed by low kinetic. In this study, an integrated\nabsorption–mineralization process with a mixture of absorbents\nKGly and Mg(OH)<sub>2</sub> was used to capture CO<sub>2</sub> from\nsimulated marine engine exhaust gas. The results revealed that the\ncapture process exhibited a distinct stepwise pattern throughout the\ncapture process, achieving an overall CO<sub>2</sub> capture efficiency\nof approximately 80% and an extent of mineralization up to 96% under\noptimal conditions. Additionally, the absorbents demonstrated a high\nstability in terms of capture efficiency and mineralization. The major\ncoproducing formed magnesium carbonate was in the form of rod or cluster\nnesquehonite (MgCO<sub>3</sub>·3H<sub>2</sub>O); moreover, it\ntransforms into flake hydromagnesite (Mg<sub>5</sub>(CO<sub>3</sub>)<sub>4</sub>(OH)<sub>2</sub>·4H<sub>2</sub>O) at temperatures\nabove 70 °C. The application of the proposed methodology on a\n1700TEU container vessel would be expected to result in a profit of\n524.8 USD for each ton of CO<sub>2</sub> captured, with a negative\ncarbon emission of 3.03 × 10<sup>8</sup> kg over a 30 year life\nspan.