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 CO2 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 CO2 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 CO2 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 (MgCO3·3H2O); moreover, it transforms into flake hydromagnesite (Mg5(CO3)4(OH)2·4H2O) 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 CO2 captured, with a negative carbon emission of 3.03 × 108 kg over a 30 year life span.