This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Three-Way Conversion Catalysts: Effect of Closed-Loop Feed-Back Control and Other Parameters on Catalyst Efficiency
Annotation ability available
Sector:
Language:
English
Abstract
Monolithic three-way conversion (TWC) catalysts, at different precious metal concentrations, were aged on an engine dynamometer with fuel doped with lead (0.012 g Pb/gal). These catalysts were subsequently evaluated on an engine dynamometer to examine the effects of air/fuel ratio set point, temperature, and air/fuel ratio amplitude and frequency on the conversion efficiencies for NOx CO and HC. In all evaluations, as the precious metal concentration increased from 5 g/ft3 to 40 g/ft3, the NOx CO and HC conversions increased. Also, the smallest effect of precious metal loading on catalyst efficiency was found at the smallest air/fuel amplitude (±0.3 A/F). The highest overall conversions of NOx CO and HC were obtained at the stoichiometric control point for perturbations of ±0.3 A/F amplitude. Therefore, it appears that a considerable savings in precious metals can be realized if the A/F amplitude of a closed-loop feed-back control system is small (±0.3 A/F). On the other hand, the higher the oscillation frequency of the feed-back control system, the higher the NOx CO and HC conversions. Thus, an additional savings in precious metals may be achieved if the control frequency is increased. Since the A/F perturbation amplitude and frequency, catalyst temperature range, A/F control point, and catalyst precious metal concentration all combine to affect the NOx CO and HC conversion efficiency, the selection of the precious metal loading of the TWC catalyst, the catalyst strategy (single or dual-bed system), and the A/F set point largely depend on the characteristics of the feed-back control system and the concentration of NOx CO and HC emissions from the engine.
Recommended Content
Authors
Citation
Falk, C. and Mooney, J., "Three-Way Conversion Catalysts: Effect of Closed-Loop Feed-Back Control and Other Parameters on Catalyst Efficiency," SAE Technical Paper 800462, 1980, https://doi.org/10.4271/800462.Also In
References
- Canale, R. P. Winegarden, S. R. Carlson C. R. Miles, D. L. “General Motors Phase II Catalyst System,” SAE Paper No. 780205 1978
- Wallman S. Engh, G. T. “Development of the Volvo Lambda Sond System,” SAE Paper No. 770295 1977
- Mooney, J. J. Thompson C. E. Dettling, J. C. “Three-Way Conversion Catalysts: Part of the New Emission Control System,” SAE Paper No. 770365 1977
- Gandhi, H. S. Piken, A. G. Shelef, M. Delosh, R. G. “Laboratory Evaluation of Three-Way Catalysts,” SAE Paper No. 760201 1976
- Gandhi, H. S. Piken, A. G. Stepien, H. K. Shelef, M. Delosh R. G. Heyde, M. E. “Evaluation of Three-Way Catalysts, Part II.” SAE Paper No. 770196 1977
- Summers J. C. Monroe, D. R. “Design Factors of Dual Bed Catalysts,” September 1979
- Hegedus, L. L. Summers, J. C. Schlatter, J. C. Baron, K. “Poison-Resistant Catalysts for the Simultaneous Control of Hydrocarbon, Carbon Monoxide, and Nitrogen Oxide Emissions,” Journal of Catalysis 56 321 1979
- Skomoroski R. M. Dettling, J. C. “Exploratory Study of Round Corner Cells in Automotive Monolithic TWC Catalysts,” To be presented at the SAE Meeting, Detroit February 1980
- Yao, Y-F Y. “The Oxidation of CO and C 2 H 4 over Metal Oxides, V. SO 2 Effects,” Journal of Catalysis 39 104 1975
- Kummer, J. T. Yao, Y-F Y. McKee, D. “Honeycomb Auto Exhaust Catalysts Containing Copper Chromite and Palladium,” SAE Paper No. 760143 1976
- Heyde, M. E. Adawi, M. K. Anderson, D. H. Schroeder M. P. Delosh, R. G. “Dynamometer Test Procedures for Three-Way Catalyst Screening,” SAE Paper No. 770371 1977
- Joy, G. C. Molinaro F. S. Lester, G. R. “Water-Gas Shift and Steam Reforming Ability of Group VIII Metals in Simulated Automotive Exhaust,” paper presented at the 6th North American Catalysis Society Meeting, Chicago, Illinois March 1979
- Schlatter J. C. Mitchell, P. J. “Three-Way Catalyst Response to Transients,” August 1979
- Öser, P. “Catalyst Systems with an Emphasis on Three-Way Conversion and Novel Concepts,” SAE Paper No. 790306 1979
- Schlatter, J. C. Sinkevitch, R. M. Mitchell, P. J. “A Laboratory Reactor System for Three-Way Catalyst Evaluation,” January 1979
- Taylor K. C. Schlatter, J. C. “Selective Reduction of Nitric Oxide over Noble Metals,” June 1979