Catalytic Control of Emissions from M-85 Fueled Vehicles

The performance of platinum/rhodium based TWC catalysts was compared to that of palladium/rhodium based TWC catalysts for the control of emissions from an M-85 fueled vehicle. The catalysts were artificially aged on an engine test stand using a simulated fuel cut aging cycle. The evaluation test cycle was the US FTP-75 test. A REGA 7000 FTIR system was used to specifically monitor methanol and formaldehyde emissions. Double layered palladium/rhodium based TWC catalysts exhibited better methanol and formaldehyde removal as well as superior overall performance. Essentially all of the hydrocarbon emission occurred during cold start. It was demonstrated that significant reduction in formaldehyde and methanol emission could be achieved by presenting a hotter exhaust gas to the converter by use of a small starter catalyst located near the engine.