■ A research team led by Dr. Sun-Mi Hwang from the Clean Air Research Laboratory at the Korea Institute of Energy Research (KIER, President Hakgeun Jeong) has developed novel catalysts as an all-in-one solution to address exhaust emissions from eco-friendly ammonia-fueled ships. This technology can simultaneously and cost-effectively remove various greenhouse gases from ammonia combustion, and is therefore expected to significantly contribute to achieving carbon neutrality in the maritime industry.

□ Ammonia has emerged as a promising next-generation fuel to achieve carbon neutrality in the maritime industry, owing to its minimal greenhouse gas emissions and advantages in transport and storage compared to fossil fuels. During combustion, however, ammonia produces harmful byproducts including nitrogen oxides (NOx), unburned ammonia, and notably nitrous oxide (N₂O)-a potent greenhouse gas with a global warming potential (GWP) roughly 300 times higher than that of carbon dioxide (CO2). If emitted untreated, these substances could worsen environmental impacts rather than mitigating them.

□ While conventional diesel ships use existing catalysts to treat only nitrogen oxide emissions, ammonia-fueled ships require separate catalysts and additional equipment to eliminate nitrous oxide and unburned ammonia as well. These requirements demand more onboard space and increase installation costs, posing a primary barrier to commercialization.

■ To address these limitations, the KIER research team developed a hybrid catalyst that provides an all-in-one solution, simultaneously eliminating nitrogen oxides and unburned ammonia. The team also formulated an advanced nitrous oxide decomposition catalyst, providing an efficient path to treat total exhaust emissions without the need for additional equipment.

□ Conventional noble metal-based catalysts are not only expensive: their catalytic decomposition process also triggers the unintended formation of other nitrogen oxides. Furthermore, existing catalysts for nitrous oxide reduction lack economic viability, as they require separate reducing agents and high operating temperatures exceeding 450 °C.

□ In contrast, the newly developed hybrid catalyst demonstrates significantly improved economic feasibility. Most notably, this catalyst is at least 80% less costly than existing noble metal alternatives. Moreover, catalyst usage can be reduced by up to 50%, as a single catalyst layer simultaneously decomposes both ammonia and nitrogen oxides with an efficiency of approximately 99%.

□ Additionally, the newly developed nitrous oxide decomposition catalyst operates at 350 °C-matching the actual exhaust gas temperatures of ships-which is approximately 100 °C lower than that of conventional commercial catalysts. This catalyst decomposes nitrous oxide with over 99% efficiency without requiring external reducing agents, thereby significantly streamlining the overall system.

□ Notably, both newly developed catalysts can be directly integrated into existing exhaust treatment systems on diesel ships, enabling rapid commercialization.

■ "Our catalysts mark a critical breakthrough in overcoming the most formidable barrier to ammonia-fueled shipping by simultaneously eliminating diverse exhaust emissions," said Dr. Sun-Mi Hwang, lead researcher of the project. "This technology precisely aligns with industrial demand by minimizing onboard equipment space, reducing system weight, and improving maintenance efficiency. Moving forward, we will continue to advance the technology through pilot demonstrations and facilitate its commercialization. This will enable the country's shipbuilding and shipping industries to achieve a robust competitive edge in the eco-friendly vessel market.“

□ This study was conducted under the internal research program of KIER, with the key findings published in Applied Catalysis B: Environment and Energy (IF 19.7), a leading journal in energy and environmental science. The KIER research team plans to further scale up and validate the newly developed catalyst technology through pilot-scale demonstrations on ammonia-fueled engine systems.