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EVALUATION OF THREE-WAY CATALYSTS. PART II
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Abstract
This is a continuation of our earlier paper on the laboratory evaluation of three-way catalysts, SAE 76201. A number of recent 3-way catalyst formulations were evaluated in a laboratory flow-reactor when fresh, after 25,000 simulated miles on a pulse-flame reactor and after 100 or 200 hours of accelerated AMA dynamometer durability. A comparison was made of the effects of contaminant levels on the performance of pulsator - and dynamometer-aged selected catalysts. The 4-fold decrease in contaminant (lead and phosphorus) levels in 76/77 certification fuel compared with the 75/76 fuel significantly improved the durability of 3-way catalysts. The problems of increased NH3 formation on pulsator - and dynamometer-aged catalysts which contain base-metal oxides as oxygen-storage or water-gas shift components is attributed to S-poisoning. An inverse relationship between NH3 formation and the amount of rhodium on aged 3-way catalysts was noted. The effects of deliberate misfire on the selectivity and activity characteristics are discussed. Further, the role of the water-gas shift and steam-reforming components in extending the “window” was studied. The effect of temperature and of inlet CO (H2) and hydrocarbon concentration on these reactions was investigated separately on single component samples and fully formulated catalysts. The extent of sulfate formation over typical fresh and dynamometer-aged 3-way catalysts is shown. The relatively small effect of Rh levels in 3-way catalysts on the extent of the sulfate formation is attributed to the possible enrichment of the catalyst surface by Rh, under oxidizing conditions, thereby resulting in a lower Pt/Rh ratio on the surface of the catalyst than in the bulk.
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Authors
- H. S. Gandhi - Research Staff, Ford Motor Co.
- A. G. Piken - Research Staff, Ford Motor Co.
- H. K. Stepien - Research Staff, Ford Motor Co.
- M. Shelef - Research Staff, Ford Motor Co.
- R. G. Delosh - Advanced Engine Engineering, Ford Motor Company
- M. E. Heyde - Advanced Engine Engineering, Ford Motor Company
Citation
Gandhi, H., Piken, A., Stepien, H., Shelef, M. et al., "EVALUATION OF THREE-WAY CATALYSTS. PART II," SAE Technical Paper 770196, 1977, https://doi.org/10.4271/770196.Also In
References
- Gandhi H. S. Piken A. G. Shelef M. Delosh R. G. “Laboratory Evaluation of Three-Way Catalysts” Paper 760201 SAE Automotive Engineering Congress and Exposition Detroit, Michigan 1976
- Motor Vehicle Manufacturing Association (MVMA) Information Bulletin August 1975
- Federal Register 40 157 August 1975
- Heyde M. E. Adawi M. K. Anderson D. H. Schroeder M. P. Delosh R. G. “Dynamometer Test Procedure for Three-Way Catalyst Screening” SAE Automotive Engineering Congress Detroit, Michigan February 1977
- Hammerle R. H. Mikkor M. “Some Phenomena Which Control Sulfuric Acid Emission from Automotive Exhaust” Paper 750097 SAE Automotive Engineering Congress and Exposition Detroit, Michigan 1975
- Mikkor M. Hammerle R. H. Truex T. “Effects of Hydrocarbons, Carbon Monoxide and Oxygen on Sulfuric Acid Emissions from an Automotive Catalyst” Paper 43 Symposium on Auto Emission Catalysis, Division of Colloid and Surface Chemistry, American Chemical Society 170th Annual Meeting Chicago August 1975
- Gandhi H. S. Otto K. Piken A. G. Shelef M. “Sulfate Formation: Catalysts and Gas-Phase Composition Effects on Pulsators and Comparison of Three-Way with Oxidation Catalysts” Environmental Science and Technology
- Taylor K. C. “Sulfur Storage on Automotive Catalysts” Symposia Division of Petroleum Chemistry American Chemical Society 21 4 September 1976
- Yao H. C. Shelef M. “IR Studies of SO 2 Adsorption on Supported Pt and Rh Catalysts”
- 11. Stabilized Rhenium Catalyst
- Yao H. C. Japar S. Shelef M. “Characterization of Supported Metal Catalysts: Rh on γ-Al 2 O 3 ”
- Schmidt L. D. Luss D. “Physical and Chemical Characterization of Platinum-Rhodium Gauze Catalysts” Journal of Catalysis 22 269 1971