NYK Line, in collaboration with Mitsubishi and Daihatsu corporate partners, has confirmed an onboard methane oxidation rate of over 90% during sea trials of its new catalyst system. Installed on the LNG bunkering vessel KEYS Azalea, the tech represents a significant breakthrough in commercializing systems that neutralize unburned methane slip in dual-fuel marine engines.
Tokyo | May 15, 2026 – In a major technical milestone for the LNG dual-fuel engines and LNG bunkering sectors, Japan’s Nippon Yusen Kaisha (NYK Line) has successfully conducted the first onboard measurement of a pioneering methane oxidation catalyst system.
The full-scale prototype, installed aboard the operational LNG bunkering vessel (LNGBV) KEYS Azalea, achieved a remarkable methane oxidation rate exceeding 90% as a standalone exhaust gas treatment unit. This significantly outperforms the 70% reduction rate initially recorded during earlier land-based engine simulation trials.
The milestone marks a crucial step forward for the global maritime industry’s efforts to mitigate “methane slip”, the escape of unburned methane (CH4) into the atmosphere, which remains one of the most prominent environmental and regulatory hurdles facing LNG as a marine fuel.
The Technology: Taming the Methane Slip Challenge
While liquefied natural gas (LNG) substantially cuts carbon dioxide (CO2), sulfur oxides (SOx), and particulate matter compared to conventional heavy fuel oils, unburned methane escaping through the exhaust stack poses a distinct environmental threat due to its high global warming potential.
The newly tested methane oxidation catalyst system counters this by triggering a chemical reaction where unburned CH4 in the engine exhaust gas reacts with oxygen (O2) to convert cleanly into carbon dioxide (CO2) and water (H2O).
CH4 + 2 O2 -> CO2 + 2 H2O
This specific system represents a collaborative joint development integrating the specialized technical expertise of four prominent Japanese maritime and heavy engineering companies:
- Mitsubishi Heavy Industries Marine Machinery & Equipment Co., Ltd. (MHI-MME): Responsible for the core catalyst system design and precision manufacturing.
- Mitsubishi Shipbuilding Co., Ltd. (MHIMSB): Spearheaded the complex shipboard engineering and installation architecture.
- DAIHATSU INFINEARTH MFG. CO., LTD. (IE): Led internal combustion engine optimization to seamlessly integrate the catalyst layout.
Operational Trial Aboard the ‘KEYS Azalea’
To rigorously verify the technology under genuine marine operating conditions, a full-scale prototype has been deployed for a long-term, one-year operational trial.
The testbed vessel, KEYS Azalea, is a specialized LNG bunkering vessel that actively supplies LNG fuel to ocean-going ships. The ship is owned by KEYS Bunkering West Japan Co., Ltd. and technically managed by NYK Group subsidiary Taiheiyo Enkai Kisen Co., Ltd.
Operating primarily across the vital shipping lanes of Japan’s Kyushu and Seto Inland Sea regions, the vessel’s ongoing operations will provide the engineering partners with continuous, real-world performance validation data to drive commercial application.
The successful onboard measurement follows hot on the heels of the technology receiving an Approval in Principle (AiP) from classification society ClassNK, validating its regulatory and safety feasibility for wider market deployment.
“The NYK Group is actively promoting the use of next-generation fuels, including LNG, to achieve decarbonization in maritime transport. We will continue working to reduce greenhouse gas emissions from vessels and minimize environmental impact.” – NYK Line Stated
About NYK Line
Established in 1885 in Japan, NYK Line, formally known as Nippon Yusen Kabushiki Kaisha, has emerged as a global leader in the maritime industry over its 135-year history. Operating a diverse fleet, including container ships, bulk carriers, and tankers, NYK serves over 800 locations worldwide, offering a comprehensive suite of shipping services.
NYK Line has earned recognition for its commitment to innovation, sustainability, and safety, navigating the complexities of global logistics with diligence and foresight. This ongoing dedication underscores NYK’s pivotal role in shaping the future of ocean transport and reaffirms its status as a cornerstone of the maritime landscape.
Source NYK Group