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The use of catalytic aftertreatment to reduce harmful gases in the exhaust streams of 2-wheel vehicles powered by small engines is becoming widespread as increasingly restrictive emissions standards are enacted. The primary exhaust gas pollutants are carbon monoxide (CO) and hydrocarbons (HC) for vehicles equipped with 2-stroke engines and CO for those using 4-stroke power plants. Because the exhaust streams of these small engines also contain significant concentrations of oxygen, catalytic aftertreatment is a very effective approach for oxidizing these contaminants to carbon dioxide and water. In order to assure the maximum long term benefits of catalytic aftertreatment, it is necessary to understand not only the factors responsible for high initial activity, but also the mechanisms by which a catalyst's performance is negatively impacted.

The use of catalytic aftertreatment to reduce residual hydrocarbons and carbon monoxide from the exhaust stream of 2-stroke 2-wheel vehicles is reported. The impact of applying three different catalyst technologies to the exhaust streams of two motorcycles was examined. Mass emission and modal results generated from 50cc and 110cc motorcycles during the India Driving Cycle (IDC) were used to characterize catalyst performance. The results indicate that the effective implementation of catalytic aftertreatment to 2-stroke 2-wheel vehicles depends strongly on both catalyst formulation and the specific application. Catalysts can be formulated to possess desired selectivity allowing flexibility in meeting emissions standards.