The Catalytic Reduction of Hydrocarbons and Carbon Monoxide in Small Two-Stroke Engine Powered Vehicle Exhaust Streams

The inefficient use of fuel by small 2-stroke powered 2-wheel vehicles results in high releases of hydrocarbons and carbon monoxide to the atmosphere. The presence of significant levels of oxygen (O₂) in the exhaust stream creates an environment that is favorable for the use of catalytic aftertreatment to oxidize hydrocarbons and carbon monoxide to carbon dioxide and water, thereby eliminating or reducing the deleterious nature of 2-stroke engine exhaust emissions. This investigation examines the impact of catalyst formulation, operating temperature, and exhaust gas composition, on the performance of catalysts designed for use with these small 2-stroke power plant applications. It is demonstrated that catalysts can be formulated to possess specific performance objectives through the appropriate combination of noble metals and washcoating components. The non-noble metal components of a catalyst formulation are observed to be crucial to catalyst performance. Aging data shows that catalysts can be formulated to possess the durability required for long term use in the demanding conditions that exist in 2-stroke power plant exhaust systems.