Japanese shipping firm NYK on Thursday (14 May) said it has conducted its first onboard measurement in a demonstration test of a methane oxidation catalyst system for marine engines fuelled by liquefied natural gas (LNG).
This demonstration test is being carried out in collaboration with Mitsubishi Heavy Industries Marine Machinery & Equipment (MHI-MME), Mitsubishi Shipbuilding Co., Ltd. (MHIMSB), and Daihatsu Infinearth MFG (IE).
The catalyst system has been installed on the LNG bunkering vessel KEYS Azalea, which supplies LNG fuel to ships. The vessel is owned by KEYS Bunkering West Japan and managed by Taiheiyo Enkai Kisen, an NYK Group company.
In LNG-fuelled marine engines, “methane slip” can occur when some of the methane in the fuel does not burn completely and escapes into the atmosphere. Because methane has a higher global warming potential than carbon dioxide, reducing methane slip is an important technical challenge for decarbonising maritime transport.
The methane oxidation catalyst system reduces these emissions by oxidising methane in the exhaust gas produced by LNG-fueled engines.
This catalyst system was developed by integrating each partner’s specialised technological expertise: MHI-MME’s design and manufacturing of catalyst systems, MHIMSB’s shipbuilding, and IE’s engine optimization.
In prior tests on land-based engines, the system demonstrated an initial methane oxidation rate of at least 70% (i.e., at least 70% methane removal). In the latest onboard measurement during this demonstration, the system achieved over 90% methane oxidation as a standalone exhaust treatment unit.
As part of this demonstration, a full-scale prototype has been installed aboard KEYS Azalea for a one-year trial period. Operating mainly in the Kyushu and Seto Inland Sea regions, the vessel is now undergoing performance verification under actual operating conditions to support practical application.
Photo credit: NYK
Published: 19 May, 2026
