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Catalytic control of motorcycle vehicle emissions requires that the catalytic element be carefully integrated into the exhaust system. The catalyst element physical parameters are optimized to achieve specific exhaust tuning requirements. Since the converter is located inside the muffler, the peak temperatures can severely stress both the catalytic active washcoat materials and the currently used metal monolith structure under some operating conditions. This paper addresses the development of an alternative ceramic monolithic catalyst that can be used for 2 and 4-stroke motorcycle applications. A new mounting technique was developed to contain the ceramic catalytic unit within a holder or converter shell with sufficient strength and durability to withstand the severe environment of 2-stroke engine exhaust.

Motorcycle exhaust emission standards throughout the world are becoming more stringent. Emission control systems utilizing the catalytic converter are already in production in Taiwan for 2-stroke engine motorcycles. Catalysts designed for 2-stroke engines encounter a more severe exhaust environment than do those designed for 4-stroke engines. The two aspects of increased severity are the higher temperatures and higher stresses due to engine vibrations. Precious metal catalysts have been designed to operate in the thermal environment of 2-stroke engines and such catalysts have been successfully applied to both metal and ceramic substrates. However, until now, only the metal substrate catalysts have been utilized in motorcycle application. Ceramic based catalysts have not been considered because the mounting material that holds the catalyst substrate in place did not have enough durability to withstand the thermal/vibrational forces encountered in 2-stroke engine exhaust.

H2S emissions from a three-way catalyst are suppressed by incorporating copper or manganese oxide into a section downstream of the three-way catalyst.

A reliable engine aging method is required to screen full size catalysts for high temperature applications typical of European autobahn wide open throttle driving. Exhaust emission control catalysts will be exposed to temperatures exceeding 850C under these conditions. This paper describes one method of using an engine to rapidly age catalysts under conditions which nearly duplicate wide open throttle exhaust gas composition and temperature. The method uses a V-8 engine as a gas generator, combines and thoroughly mixes the exhaust from both banks, then divides the mixed exhaust into two equal streams, reintroduces air/fuel perturbations, and passes each equal perturbated flow through a catalyst. This V-8 engine aging method of dual converters produces an exhaust stream of equal flow and composition across both catalysts and overcomes the concerns of other comparative aging techniques.