Technical Paper
Exhaust Catalyst Selection for Small Two-Stroke Engines
1995-09-01
951765
A laboratory test has been used to evaluate the behavior of different oxidation catalyst formulations for conventional two-stroke engines. The test gas composition was as close as possible to the real exhaust gas composition with respect to its hydrocarbon and oxygen contents. Small size catalyst samples were located inside a quartz tube and heated by an electric furnace. Several wash-coat types and noble metal formulations applied on metallic substrates were compared. Determinations included light-off temperature and pollutant conversion rates. It was generally observed that the most active catalysts for hydrocarbon elimination produced the highest amount of CO at temperatures between 350 and 500°C. This was due to the substoichiometric oxygen content of the simulated exhaust gas. Some tests were then performed to evaluate the possibility of converting the CO produced, back to CO2 and H2, by the water gas-shift reaction.