Methane and nitrogen oxides abatement from marine exhaust gases: A review on available plasma-catalytic systems

Abstract

As the maritime sector grapples with stringent emissions regulations set by the International Maritime Organization, the focus has shifted toward sustainable solutions to mitigate significant air pollution caused by ship engine emissions. This review explores the advancements in plasma-assisted technologies for the abatement of methane (CH4) and nitrogen oxides (NOx) from marine exhaust gases. Plasma-assisted techniques present innovative alternatives capable of effectively breaking down harmful pollutants like NOx, SOx, and CH4 at lower temperatures with improved energy efficiency. The review synthesizes current research on various reactor configurations (plasma-alone, in-plasma and post-plasma catalysis systems), guiding their applications towards optimized pollutant reduction in realistic exhaust gas mixtures. Key findings indicate that the integration of plasma with catalytic processes enhances the removal efficiency of both CH4 and NOx, often through synergistic interactions. Among the different plasma configurations, dielectric barrier discharge (DBD) reactor is deemed effective and scalable for pollutant removal applications. Additionally, specific energy inputs and operational parameters crucially influence the overall efficiency of these technologies. Still, testing under elevated gas temperatures to enhance efficiency, particularly in integrated plasma-catalysis configurations, while considering the complexities of catalyst management is required. Further development and refinement of these technologies is necessary to promote their up-scaling and commercial viability in maritime applications.