This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Sulfuric Acid Aerosol Emissions from Catalyst-Equipped Engines
ISSN: 0148-7191, e-ISSN: 2688-3627
Published February 1, 1974 by SAE International in United States
Annotation ability available
It has been reported by Dow Chemical Co. that oxidation catalysts cause increased particulate emissions from automotive exhausts. We find that this particulate consists of aqueous H2SO4 droplets.
Current work undertaken between Ford and Battelle Columbus Laboratories, using an engine dynamometer, shows that the fuel sulfur emerges from the engine as SO2. At 60 mph road load, a monolithic oxidation catalyst converts almost half of the SO2 into SO3, the bulk of which is emitted from the tailpipe as H2SO4. The mass median diameter is smaller than 0.25 μm. Some ammonium sulfate is present, but the predominant sulfate species is H2SO4, totalling some 40% of the gross particulate mass depending on humidity. The rest is primarily water, associated with the hygroscopic H2SO4. Without a catalyst, the H2SO4 is <1/50 as much as with catalyst, the bulk of the fuel sulfur being emitted as SO2.
CitationPierson, W., Hammerle, R., and Kummer, J., "Sulfuric Acid Aerosol Emissions from Catalyst-Equipped Engines," SAE Technical Paper 740287, 1974, https://doi.org/10.4271/740287.
- Moran John B., Manary Otto J., Fay Russell H., and Baldwin Michael J., “Development of Particulate Emission Control Techniques for Spark-Ignition Engines.” EPA Office of Air Programs Publication APTD-0949 (National Technical Information Service Report PB 207312), July 1971.
- Gentel James E., Manary Otto J., and Valenta Joseph C., “Characterization of Particulates and Other Non-Regulated Emissions from Mobile Sources and the Effects of Exhaust Emissions Control Devices on These Emissions.” EPA Office of Air and Water Programs Publication APTD-1567 (available from National Technical Information Service, U.S. Dept. of Commerce, 5285 Port Royal Road, Springfield, Va. 22151), March 1973.
- Willard Hobart H. and Furman N. Howell, “Elementary Quantitative Analysis.” Third ed. New York: D. Van Nostrand Co., 1940.
- Harkins J. H. and Nicksic S. W., Environmental Sci. & Technol., Vol. 1 (1967), p. 751.
- Latimer Wendell M. and Hildebrand Joel H., “Reference Book of Inorganic Chemistry.” Third ed. New York: The MacMillan Co., 1951.
- Stokes R. H. and Robinson R. A., Ind. Eng. Chem., Vol. 41, (1949), p. 2013; Lange N. A., “Handbook of Chemistry” (Revised 10th ed., 1967), p. 1435; Air Quality Criteria for Sulfur Oxides, NAPCA Publ. No. AP-50 (National Technical Information Service Report PB 190252), January 1969.
- Shelton Ella M., “Motor Gasolines, Summer 1971.” Petroleum Products Survey No. 73, January 1972; Shelton Ella M., “Motor Gasolines, Winter 1971-72.” Petroleum Products Survey No. 75, June 1972; MVMA Information Bulletin, Summer Season Quarter Report-Southwest Research Institute, Nov. 2, 1972.
- van der Zijden M. J., van Hinte J. E., and van den Ende J. C., J. Inst. Petroleum, Vol. 36 (1950), p. 561.
- Private communication from Jack G. Calvert, Chemistry Dept., Ohio State University, 1972.
- Other evidence that the reaction of SO3 with water is rapid comes from the fact, crucial to the contact process for sulfuric acid manufacture, that the SO3 formed in the process is more readily absorbed from the gas stream by concentrated H2SO4 than by water. The apparent explanation of the phenomenon is that a fog of H2SO4 droplets is formed by reaction of SO3 with water vapor. The Brownian motion of the H2SO4 droplets is quite slow compared with that of gas molecules; but with H2SO4 as the absorbing medium there is little water vapor, no fog forms, and the rapidly moving SO3 molecules are more readily absorbed when the gas is bubbled through the acid (see Ref. 5).
- Lisle E. S. and Sensenbaugh J. D., Combustion, Vol. 36, No. 7 (January 1965), p. 12.
- Müller P., Chem.-Ing.-Technol. Vol. 31 (1959), p. 345.
- Hunter Joseph E., “Studies of Catalyst Degradation in Automotive Emission Control Systems.” Paper 720122 presented at SAE Automotive Engineering Congress, Detroit, January 1972.
- Federal Register Volume 37, Number 221, Part II, § 85.075-24 and Appendix I, November 15, 1972.
- Melton C. W., Mitchell R. I., Trayser D. A., and Foster J. F., “Final Summary Report on Chemical and Physical Characterization of Automotive Exhaust Particulate Matter in the Atmosphere” to Coordinating Research Council and EPA from Battelle Columbus Laboratories, CRC-APRAC Project No. CAPE-19-70, June 14, 1973.
- Goksøyr H. and Ross K., J. Inst. Fuel, Vol. 35 (1962), p. 177.