Modeling the Reduction of Ship Exhaust Emissions through CO₂ Capture/Chemical Conversion and SO₂ Seawater Scrubbing

Developing innovative, energy-efficient technologies to capture CO2 from marine emissions and convert it represents an effective way to move toward a circular approach to reduce CO2 emissions. Additionally, SO2 removal, as a short-term interim solution for the current maritime sector, allows the use of less desulfurized/expensive fuels to meet International Maritime Organization emission standards. In this context, we investigated an integrated process of capturing CO2/SO2 onboard ships and converting captured CO2, thus initiating a process close to carbon neutrality. CO2 absorption by monoethanolamine and SO2 scrubbing with seawater were envisaged in packed-bed columns, whose hydrodynamics and performance were analyzed under vertical, inclined, and rolling conditions using three-dimensional (3D) Eulerian models to understand their behavior under changing ocean states. CO2 conversion via an integrated process combining a sorption-enhanced reverse water gas shift and sorption-enhanced methanol synthesis was proposed. By including a reverse water gas shift and in situ H2O removal, CO and methanol yields were significantly improved.