Honda Motor Co., Ltd., announced it has developed a next-generation diesel engine that reduces exhaust gas emissions to a level equal to a gasoline engine. Honda’s next-generation diesel engine employs a NOx catalytic converter that enables a reduction in NOx emissions sufficient to meet stringent U.S. Environmental Protection Agency (EPA) Tier II Bin 5 emissions requirements (based on Honda’s internal calculations). Honda says this catalytic converter features the world’s first innovative system using the reductive reaction of ammonia generated within the catalytic converter to “detoxify” nitrogen oxide (NOx) by turning it into nitrogen (N2). Other automakers are developing urea-based systems to control diesel emissions. The new catalytic converter utilizes a two-layer structure: one layer adsorbs NOx from the exhaust gas and converts a portion of it into ammonia, while the other layer adsorbs the resulting ammonia, and uses it later in a reaction that converts the remaining NOx in the exhaust into nitrogen (N2). Ammonia is a highly effective reagent for reducing NOx into N2 in an oxygen-rich, lean-burn atmosphere. This ability to generate and store ammonia within the catalytic converter has enabled Honda to create a compact, lightweight NOx reduction system for diesel engines. The system also features enhanced NOx reduction performance at 200–300ºC, the main temperature range of diesel engines. Honda plans to introduce its next-generation diesel engine in the U.S. within three years.