Palladium and Platinum/Rhodium Dual-Catalyst NLEV and Tier IIa Close-Coupled Emission Solutions ASEC Manufacturing/Delphi Automotive Systems

Format:

Conference/Event

Author/Creator:

Williamson, W. B., author.

Conference Name:

SAE 2001 World Congress (2001-03-05 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2001

Summary:

Dual-monolith converters containing Pd-only catalysts followed by Pt/Rh three-way catalysts (TWCs) provide effective emission solutions for NLEV and Tier IIa close-coupled dual-bank V-8 applications due to optimal hydrocarbon and NOx light-off, transient NOx control, and balance of precious metal (PGM) usage. Dual-catalyst [Pd +Pt/Rh] systems on a 5.3L V-8 LEV light truck vehicle were characterized as a function of PGM loading, catalyst technology, and substrate cell density.NLEV hydrocarbon emission control of the 6500 lb vehicle was optimal using dual 1.2L converters with each containing front ceria-free Pd catalysts coupled with rear Pt/Rh TWCs. Advanced non-air prototype calibrations coupled with reduced catalyst washcoat mass on 600cpsi/4mil substrate resulted in minimal Pd usage of 0.02 toz/vehicle due to achieving catalyst inlet temperatures of 350-400°C in <10 sec on both banks of the V-8 engine. The lower mass Pd washcoat contribution was 10-15 mg/mi NMHC due to improved light-off performance.The more stringent Tier IIa NOx emission levels required larger converter volumes, higher Pd content, increased oxygen-storage capacity, and higher cell density 600cpsi/3mil substrates. Larger dual close-coupled 1.67L converters with front ceria-containing Pd catalysts substantially improved NOx performance during transient A/F excursions. The front Pd ceria-containing technology improved NOx by 20mg/mi compared to the ceria-free technology, but the ceria-free technology had 10mg/mi better NMHC control. The higher cell density 600cpsi/3mil substrate resulted in 10-15mg/mi lower NOx emissions

Notes:

Vendor supplied data

Publisher Number:

2001-01-0923

Access Restriction:

Restricted for use by site license