Integrated Absorption and Mineralization to Carbon Capture from Marine Engine Exhaust Gases and Coproduce Magnesium Carbonate

The issue of air pollution caused by fossil-fuel-powered ships has been adequately addressed, yet the challenges posed by greenhouse gas emissions still require further attention. Onboard carbon capture and storage technology represents effective means of reducing CO 2 emission from ships. However, the general amine-based solvent process demands significant power input, whereas carbon mineralization processes were slowed by low kinetic. In this study, an integrated absorption–mineralization process with a mixture of absorbents KGly and Mg(OH) 2 was used to capture CO 2 from simulated marine engine exhaust gas. The results revealed that the capture process exhibited a distinct stepwise pattern throughout the capture process, achieving an overall CO 2 capture efficiency of approximately 80% and an extent of mineralization up to 96% under optimal conditions. Additionally, the absorbents demonstrated a high stability in terms of capture efficiency and mineralization. The major coproducing formed magnesium carbonate was in the form of rod or cluster nesquehonite (MgCO 3 ·3H 2 O); moreover, it transforms into flake hydromagnesite (Mg 5 (CO 3 ) 4 (OH) 2 ·4H 2 O) at temperatures above 70 °C. The application of the proposed methodology on a 1700TEU container vessel would be expected to result in a profit of 524.8 USD for each ton of CO 2 captured, with a negative carbon emission of 3.03 × 10 8 kg over a 30 year life span.