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The use of methanol as a “clean fuel” appears to be a viable approach to reduce air pollution. However, concern has been expressed about potentially high formaldehyde emissions from stoichiometrically operated light-duty vehicles. This paper presents results from Task 1 of an emission test program conducted for the California Air Resources Board (CARB) and the South Coast Air Quality Management District (SCAQMD) to identify advanced catalyst technology to reduce formaldehyde emissions without compromising regulated emission control. A hybrid M90 test vehicle was used to evaluate 18 unaged catalyst systems for formaldehyde, methanol, gasoline derived hydrocarbon, organic material hydrocarbon equivalent mass, carbon monoxide, and oxides of nitrogen emissions. The vehicle was operated on a chassis dynamometer using the FTP driving cycle. Catalyst systems evaluated included electrically-heated, manifold, close-coupled, and underbody catalysts, as well as combinations of the above.

An extensive literature search was conducted and potential additive candidates were identified to improve the safety aspects associated with the use of methanol as a motor fuel. Before any laboratory measurements were conducted, candidate additives were evaluated for possible formation of known or suspected toxic compounds as combustion products. The remaining potential additives were then screened for their effectiveness in improving methanol fuel properties in a laboratory test program emphasizing flame luminosity, lubricity, and flammability. Flame luminosity was measured with a specially designed system to monitor the light produced by the flame in lux. Lubricity was measured with a Ball-on-Cylinder Lubricity Evaluator (BOCLE). For flammability limits, a device was designed to determine the presence of flammable vapors above the liquid at different additive concentrations.