UltraThin wall catalyst solutions at similar restriction and precious metal loading

摘要

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 RATsm-820 prior to the emission evaluations. The FTP results show that washcoat technology and catalyst substrate can have a significant impact on HC and NO{sub}x 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 NO{sub}x emissions.