This content is not included in your SAE MOBILUS subscription, or you are not logged in.
A Three-Way Catalytic Muffler Using Progressive Air Injection for Automotive Exhaust Gas Purification
ISSN: 0148-7191, e-ISSN: 2688-3627
Published February 01, 1977 by SAE International in United States
Annotation ability available
The present paper shows that the simultaneous removal with a single catalytic muffler of the three types of pollutants (NO, CO and HC) is possible without requiring a very precise adjustment of the engine equivalence ratio or permanent control of the supply of secondary air added ahead of the muffler.
The system studied consists of a muffler in which secondary air is supplied from a plurality of points located within the catalyst bed itself in order to have an oxygen concentration in the treated gas that increases progressively between the inlet and the outlet.
Experimental muffler designs are presented for monolithic or bead-type catalysts.
The numerous advantages of this technique as compared with the well-known dual bed system are described. It is in particular shown that the NO reduction rate is increased on precious metal catalysts when oxygen is added to some extent in a reducing exhaust gas, with maximum efficiency being reached just below the stoichiometric proportion. Ammonia formation due to the presence of oxygen is also reduced in the first part of the catalytic bed, and its reoxidation in the oxidizing section is directed toward N2 formation since oxygen is only in large excess near the outlet.
The results of several tests made on an engine bench, show that the ratio between the flow of exhaust gas and secondary air may vary widely with little change in the efficiency of the muffler. Some data obtained on a vehicle, using the CVS procedure, confirm these results.
CitationPrigent, M., Raynal, B., and Courty, P., "A Three-Way Catalytic Muffler Using Progressive Air Injection for Automotive Exhaust Gas Purification," SAE Technical Paper 770298, 1977, https://doi.org/10.4271/770298.
- Hightower J.W., “Catalysts for Automobile Emission Control”, Proceedings of the Internal Symp. on Scientific Bases for the Preparation of Heterogeneous Catalysts, Brussels, Oct. 14, 1975, Elsevier Scientific Publ. Co., Amsterdam.
- Shelef M., “Nitric Oxide: Surface Reactions and Removal from Auto Exhaust”, Catalysis Review, Vol. 11, p. 1, 1975, Marcel Dekker.
- Wei J., “Catalysis for Motor Vehicle Emissions”, Advances in Catalysis, Vol. 24, p. 57, 1975, Academic Press.
- Genslak S.L. and Zahorchak J.A., “Dual Catalytic Converters”, SAE 750176 Automotive Engineering Congress, Detroit, Michigan, February 1975.
- Zechnall R., Baumann G. and Eisele H., “Closed-Loop Exhaust Emission Control System with Electronic Fuel Injection”, SAE 730566 Automotive Engineering Meeting, Detroit, Michigan, May 1973.
- Blum R., “Procédé et dispositif pour épurer, rendre inodores et silencieux et détoxiquer les gaz d'échappement”, French Patent No. 754690, filed April 24, 1933.
- Stiles A.B., “Catalytic Exhaust Converter”, U.S. Patent No. 3, 186,806, filed Nov. 20, 1961.
- Tighe B., “Exhaust Systems for Internal Combustion Engines”, G.B. Patent No. 1 314 504, filed Jan. 19, 1971.
- De Palma T.V. and Perga M.W., “Methods and Means for Catalytically Treating Engine Exhaust Gases”, U.S. Patent No. 3,729,936, filed May 24, 1971
- Hass R.H., “Exhaust Gas Conversion Process”, U.S. Patent No. 3,832,443, filed Aug. 26, 1971.
- Prigent M., Courty P. and Raynal B., “Nouveau procédé pour l'épuration des gaz d'échappement des véhicules automobiles et dispositif utilisable dans ce procédé”, French Patent EN 7502680, filed Jan. 27, 1975.
- Barnes G.J. and Klimisch R.L., “Initial Performances of Supported NOx Reduction Catalysts in a Dual-Catalyst System”, SAE 740251 Automotive Engineering Congress, Detroit, Michigan, February 1974.
- Bartholomew C.H., “Reduction of Nitric Oxide by Monolithic-Supported Palladium-Nickel and Palladium-Ruthenium Alloys”, Ind. Eng. Chem., Prod. Res. Dev., Vol. 14, No. 1, p. 29-33, 1975.