1998-02-23

Emission Control Technologies for 50 and 125 cc Motorcycles in Taiwan 980938

The EPA of the Republic of China (Taiwan) will implement new emission regulations for 50-150 cc 2-stroke and 4-stroke motorcycles starting 1998. The exhaust emissions of motorcycles must be lower than 3.5 g/km CO and 2.0 g/km HC+NOx during the ECE-R40 driving cycle test. The emission legislation has a requirement for a catalyst durability life of 15,000 km. To comply with current legislation, the majority of 4-stroke motorcycles currently manufactured in Taiwan are fitted with secondary air systems, while 2-stroke motorcycles are fitted with catalytic converters. With this added equipment, 2-stroke and 4-stroke motorcycles generally can just achieve the emission targets when the motorcycles are new. However, it is an issue whether the exhaust emissions of motorcycles can meet the emission legislation after 15,000 km, because of the mass-production variation. This work presents some potential emission control strategies. Moreover, a variety of ageing methods was used to evaluate Pt/Rh and Pd-only catalysts that were installed in a 50 cc 2-stroke motorcycle and a 125 cc 4-stroke motorcycle. Our results reveal that the position of the induction of the secondary air is very important to achieve the optimal flow rate of the secondary air for a 50 cc 2-stroke motorcycle. Further, the removal capability of the catalytic converters for carbon monoxide and hydrocarbon emissions can be significantly improved by introducing secondary air. However, this results in the fact that the peak temperatures of a 50 cc 2-stroke and a 125 cc 4-stroke motorcycles will reach 1050 and 920°C, respectively. In order to overcome the severe thermal deactivation, a good thermal resistant catalyst or dual catalyst system should be considered.

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