Project at a Glance

Title: Control of benzene emissions from light-duty motor vehicles

Principal Investigator / Author(s): Heimrich, Martin J

Contractor: Department of Emissions Research, Southwest Research Institute

Contract Number: A6-204-32

Research Program Area: Emissions Monitoring & Control

Topic Areas: Mobile Sources & Fuels, Toxic Air Contaminants


Several strategies to reduce the total amount of exhaust and evaporative benzene emissions from light-duty gasoline-fueled vehicles have been investigated. A literature search was performed to determine automotive benzene emission levels and technologies for benzene emission control, Laboratory vehicle emission tests were performed to demonstrate benzene control technologies. Exhaust benzene emission control was addressed by reducing total hydrocarbon emissions (including benzene), and focused on developing strategies for specifically controlling the high level of cold-start emissions. Catalyst formulations were investigated for improved benzene conversion efficiencies. High temperature catalysts were close-coupled to the exhaust manifold to promote quicker catalyst light-off. Zeolite molecular sieves were evaluated for evaporative emission control and the results were compared to those using conventional coal- and wood-based activated carbon.

A cold-start hydrocarbon collection system was developed for this program. Hydrocarbon emissions were collected by a zeolite molecular sieve element for subsequent release to an active catalyst. Preliminary Federal Test Procedure (FTP) emission tests demonstrated a reduction in cold-start hydrocarbon emissions.

Electrically-heated catalyst systems with cold-start air injection were optimized for this program. FTP emission tests demonstrated that vehicles equipped with unaged electrically-heated catalyst systems are potentially capable of meeting the California Ultra-Low Emission Vehicle (ULEV) emission standards. Exhaust hydrocarbon speciation was performed on two vehicles, a 1990 Buick LeSabre and a 1990 Toyota Celica, equipped with optimized electrically-heated catalyst systems.

For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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