UltraThin Wall Catalyst Solutions at Similar Restriction and Precious Metal Loading

FTP and ECE + EUDC emissions are measured from six converters having similar restriction and platinum group metals on two 1999 prototype engines/calibrations. A 2.2L four cylinder prototype vehicle is used to measure FTP emissions and an auto-driver dynamometer with a prototype 2.4L four cylinder engine is used to determine the ECE + EUDC emissions. The catalytic converters use various combinations of 400/3.5 (400cpsi/3.5mil wall), 400/4.5, 400/6.5, 600/3.5, 600/4.5, and 900/2.5 ceramic substrates in order to meet a restriction target and to maximize converter geometric surface area. Total catalyst volume of the converters varies from 1.9 to 0.82 liters. Catalyst frontal area varies from 68 cm² to 88 cm². Five of the six converters use two catalyst bricks. The front catalyst brick uses either a three-way Pd washcoat technology containing ceria or a non-ceria Pd washcoat technology. Pd loadings are 0.1 troy oz. of Pd. The rear catalyst brick uses a Pt/Rh washcoat at a loading of 0.06 t.o. and a ratio of 5/1. Each converter was aged for 125 hours of RAT^sm-820 prior to the emission evaluations. The FTP results show that washcoat technology and catalyst substrate can have a significant impact on HC and NOx emissions. Results suggest that 900 cpsi substrates with three-way Pd catalyst may be a critical part of the ULEV-II emission solution. ECE+EUDC emission results suggest that non-ceria Pd front brick converters may be best for high speed NOx emissions.