How a cooler, cheaper catalyst could clean up ammonia-fueled ships

Picture an ocean-crossing engine that burns a fuel with no carbon in it—ammonia—and still faces a warming trap. One slip in the exhaust, and nitrous oxide (N2O), a greenhouse gas with a global warming potential roughly 300 times higher than carbon dioxide, can leak into the air instead of breaking apart.

That trap is what a team at the Korea Institute of Energy Research (KIER) says it has designed around. Reporting work published in Applied Catalysis B: Environment and Energy, the group led by Dr. Sun‑Mi Hwang describes an exhaust-treatment approach for ammonia-fueled ships that targets multiple pollutants at once. They report roughly 99% removal of the targeted pollutants, at temperatures engines actually see, and at far lower cost than the noble-metal standards the industry knows.

Why this is in the news now

Ammonia is on shipping’s shortlist for cutting carbon, but exhaust cleanup is not a solved problem. In material reported via phys.org, the KIER team frames that cleanup as the most formidable barrier to ammonia-fueled shipping, and presents two catalysts as an all-in-one answer. One runs at 350 °C—approximately 100 °C lower than conventional commercial catalysts and below the high operating temperatures exceeding 450 °C that have been the norm—and the overall system is described as simultaneously and cost‑effectively removing various greenhouse gases from ammonia combustion.

What’s actually new in the hardware

Two claims stand out. First, performance: the team reports approximately 99% removal of the targeted pollutants. Second, practicality: the catalysts are at least 80% less costly than existing noble‑metal alternatives, and total catalyst usage can be reduced by up to 50% because a single layer tackles multiple species at once. Those three numbers—~99%, ≥80%, and up to 50%—are what make this more than a lab curiosity.

The temperature window matters just as much. One of the catalysts is specified to operate at 350 °C. The team contrasts this with conventional commercial catalysts that need temperatures approximately 100 °C higher, and with other options that require high operating temperatures exceeding 450 °C. Running cooler opens doors: it lines up with the heat actually available in exhaust and avoids extra burners or energy penalties.

From kitchen chemistry to ship stacks: how a catalyst helps

If you’ve ever used a self‑cleaning oven, you know heat alone can break down grime. Exhaust cleanup is the same idea with molecules: you steer them onto a surface that makes the hard reactions easy. The analogy breaks down because, unlike an oven’s indiscriminate burn‑off, ship exhaust needs selectivity—turning targeted compounds into harmless nitrogen without making new problems—and it has to do it continuously at the pace of an engine.

According to the KIER team, the new setup aims to handle multiple greenhouse gases from ammonia combustion in one go. That consolidation is why they can claim less total catalyst material and a single layer doing double duty: one pass, fewer parts.

Why not just stick with today’s catalysts?

Cost and heat. Noble‑metal catalysts work but are expensive; the team states their approach is at least 80% less costly than those alternatives. And many incumbent systems want temperatures exceeding 450 °C to do their best work. The KIER catalysts shift that window down to 350 °C for the nitrous‑oxide step and report approximately 100 °C advantage over conventional commercial offerings. Those are not marginal tweaks; they change where you can bolt the unit in and how much you pay for it.

What happens if it falls short aboard a ship

The risk is in what gets through. N2O’s warming punch—roughly 300× CO₂’s global warming potential—means even small leaks matter. The reported ~99% removal target is meant to keep that punch bottled up; missing it would push warming back the wrong way just as shipping is trying to decarbonize.

What we don’t know yet

Key details are not public here: lifetime on real engines, tolerance to contaminants, maintenance intervals, and performance over duty cycles. The reports do not specify those numbers, nor do they list the exact cost breakdown behind the “at least 80% less costly” figure or how the “up to 50%” catalyst reduction scales with engine size. Those are the measurements that will decide whether the lab promise holds at sea.

The potential upside, in one sentence

If an exhaust unit can cost at least 80% less than noble‑metal systems, use up to 50% less catalyst, run at 350 °C rather than the >450 °C many systems demand, and still remove roughly 99% of the targeted pollutants, it directly addresses what Dr. Sun‑Mi Hwang has called the most formidable barrier to ammonia‑fueled shipping.

Where the findings live for the record

The study’s findings are published in Applied Catalysis B: Environment and Energy. For readers who want the technical backbone, see “K‑Ni0.4Co2.6O4 spinel catalysts for low‑temperature catalytic decomposition of N2O: Effects of K on activity and NO/NH3 resistance” (https://doi.org/10.1016/j.apcatb.2026.127204).