The Effects of the Catalytic Converter and Fuel Sulfur Level on Motor Vehicle Particulate Matter Emissions:  Gasoline Vehicles

• Published in: Environmental science & technology 2002-01, Vol.36 (2), p.276-282
• Main Authors: Maricq, M. Matti, Chase, Richard E, Xu, Ning, Podsiadlik, Diane H
• Format: Article
• Language: English
• Subjects: Aerosols; Air Pollutants - analysis; Applied sciences; Atmospheric pollution; Catalysis; Catalytic converters; Emissions; Engineering; Environmental Monitoring; Equipment Design; Exact sciences and technology; Exhaust pipes; Filters (fluid); Fuel injection; Fuels; Gasoline; Gasoline - analysis; Gravimeters; Hydrocarbons; Motor vehicles; Particle Size; Particle size distribution; Pollution; Pollution sources. Measurement results; Smog; Sulfates; Sulfur; Sulfur - analysis; Transports; Vehicle emissions; Vehicle Emissions - analysis; Wind tunnel testing
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es010961t

Scanning mobility and electrical low-pressure impactor particle size measurements conducted during chassis dynamometer testing reveal that neither the catalytic converter nor the fuel sulfur content has a significant effect on gasoline vehicle tailpipe particulate matter (PM) emissions. For current technology, port fuel injection, gasoline engines, particle number emissions are ≤ 2 times higher from vehicles equipped with blank monoliths as compared to active catalysts, insignificant in contrast to the 90+% removal of hydrocarbons. PM mass emission rates derived from the size distributions are equal within the experimental uncertainty of 50−100%. Gravimetric measurements exhibit a 3−10-fold PM mass increase when the active catalyst is omitted, which is attributed to gaseous hydrocarbons adsorbing onto the filter medium. Both particle number and gravimetric measurements show that gasoline vehicle tailpipe PM emissions are independent (within 2 mg/mi) of fuel sulfur content over the 30−990 ppm concentration range. Nuclei mode sulfate aerosol is not observed in either test cell measurements or during wind tunnel testing. For three-way catalyst equipped vehicles, the principal sulfur emission is SO2; however a sulfur balance is not obtained over the drive cycle. Instead, sulfur is stored on the catalyst during moderate driving and then partially removed during high speed/load operation.