MHI-MME, Mitsubishi Shipbuilding Obtain AiP for Methane Oxidation Catalyst System Design

Mitsubishi Heavy Industries Marine Machinery & Equipment Co., Ltd. (MHI-MME) and Mitsubishi Shipbuilding Co., Ltd., both part of the Mitsubishi Heavy Industries (MHI) Group, have obtained Approval in Principle (AiP) from Nippon Kaiji Kyokai (ClassNK) for the basic design of a methane oxidation catalyst system for marine LNG-fueled engines, jointly developed with Daihatsu Infinearth Mfg. Co., Ltd. A presentation ceremony was held today at Sea Japan 2026, an international maritime exhibition being held at Tokyo Big Sight in Koto-ku, Tokyo.

The methane oxidation catalyst system subject to the AiP oxidizes methane slip (unburned methane) contained in the exhaust gas of marine engines. Methane has a high global warming potential among greenhouse gases (GHGs), and therefore the ability to suppress its emissions is an advantage of this system. The system was developed with MHI-MME's catalyst design and manufacturing technology at its core, combined with Mitsubishi Shipbuilding's shipboard installation technology, and Daihatsu Infinearth's engine optimization technology.

Verification testing of the catalyst system is currently being conducted in cooperation with Nippon Yusen Kabushiki Kaisha (NYK Line), with a full-scale demonstrator mounted on the KEYS Azalea, an LNG bunkering vessel owned and operated by KEYS Bunkering West Japan Ltd. Initial measurements during the verification testing confirmed the expected performance of the exhaust gas treatment equipment, achieving a methane oxidation rate of more than 90% for the system alone.

Following the acquisition of AiP and the confirmation of the expected performance through verification on an actual ship (initial measurements), the partner companies plan to further accelerate development toward commercialization of the system.