FTP and US06 Performance of Advanced High Cell Density Metallic Substrates as a Function of Varying Air/Fuel Modulation

The influence of catalyst volume, cell density and precious metal loading on the catalyst efficiency were investigated to design a low cost catalyst system. In a first experiment the specific loading was kept constant for a 500cpsi and a 900cpsi substrate. In a second experiment the palladium loading was reduced on the 900cpsi substrate and the same PM loading was applied to a 1200cpsi substrate with lower volume. Finally the loading was further reduced for the 1200cpsi substrate. The following parameters were studied after aging:

• Catalyst performance of standard cell density compared to high cell density technology
• Light-off performance and catalyst efficiency as a function of Palladium loading and substrate cell density
• Catalyst efficiency as a function of AFR biasing

The performance of the aged catalysts was investigated in a lambda sweep test and in light-off tests at an engine bench. After pre-testing the catalyst were installed in a MY 2002 - V 6 vehicle to compare the performance of the aged catalysts during the FTP and US06 test cycle before and after AFR adjustments.

The test results show advantages of high cell density substrates during FTP cold start and during hot transient condition. The volume of high cell density catalyst can be reduced as compared to standard cell density substrates due to the higher specific efficiency. The palladium loading of high cell density technology can be reduced as a result of faster heat up and faster light-off during FTP cold start compared to 500cpsi catalysts. The results also demonstrate the sensitivity of emission reduction to air-fuel ratio for high cell density converters.