This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
The Relationship Between Catalyst Hydrocarbon Conversion Efficiency and Oxygen Storage Capacity
Annotation ability available
Sector:
Language:
English
Abstract
Measurements of oxygen storage capacity (OSC) and HC conversion efficiency for 17 catalysts were carried out in the laboratory. All catalysts with steady state HC efficiency below 90% were found to have roughly equivalent and very low capacities to store oxygen. However, catalyst oxygen storage capacity was seen to rise sharply with HC conversion efficiency in excess of 90 percent. These results parallel the trends which are observed between rear HEGO/EGO indexes for OBD-II catalyst monitoring and HC conversion efficiency. In addition, temperature programed reduction (TPR) was found to lend insight into the relationship between catalyst OSC and HC conversion efficiency by providing a qualitative understanding of the mechanisms by which OSC deteriorates. TPR profiles showed that most of the usable oxygen storage is derived from surface ceria which is interacted with precious metals. In-use vehicle aging to 10K miles degraded steady state HC efficiency very little but was capable of partially breaking the precious metal-ceria interaction and greatly reduced oxygen storage capacity. More long term in-use vehicle aging (100K miles) was found to completely break the precious metal-ceria interaction and resulted in catalysts with very low capacities to store oxygen.
Recommended Content
Citation
Hepburn, J. and Gandhi, H., "The Relationship Between Catalyst Hydrocarbon Conversion Efficiency and Oxygen Storage Capacity," SAE Technical Paper 920831, 1992, https://doi.org/10.4271/920831.Also In
References
- “Technical Status Update and Proposed Revisions to Malfunction and Diagnostic System Requirements Applicable to 1994 and Subsequent California Passenger Cars, Light-Duty Trucks, and Medium Duty Vehicles” Technical Support Document State of California Air Resources Board July 26 1991
- Clemmens, W.B. Sabourin, M.A. Rao, T. “Detection of Catalyst Performance Loss Using On-Board Diagnostics” SAE Paper 900062 1990
- Koupal, J.W. Sabourin, M.A. Clemmens, W.B. “Detection of Catalyst Failure On-Vehicle Using the Dual Oxygen Sensor Method” SAE Paper 910561 1991
- Gandhi, H.S. Piken, A.G. Shelef, M. DeLosh, R.G. “Laboratory Evaluation of Three-Way Catalysts” SAE Paper 760201 1976
- Fleming, W.J. Howarth, D.S. Eddy, D.S. “Sensor for On-Vehicle Detection of Engine Exhaust Gas Composition” SAE Paper 730575 1973
- Meitzler, A.H. “Application of Exhaust-Gas-Oxygen Sensor to the Study of Storage Effects in Automotive Three Way Catalysts” SAE Paper 800019 1980
- Baltusis, P.A. “Catalyst Monitor for 1994 and 1995 Model Year” Ford Motor Company SAE OBD-II Feasibility Workshop August 21-22 1991
- Wade, D.R. “Catalyst Diagnostic Index vs. Steady State HC Efficiency” General Motors SAE OBD-II Feasibility Workshop August 21-22 1991
- Yao, Y.F. “Oxidation of Alkanes over Noble Metal Catalysts” Ind. Eng. Chem. Prod. Res. Dev. 19 293 1980
- DallaBetta, R. McCune, R. Sprys, J. “Relative Importance of Thermal and Chemical Deactivation of Noble Metal Automotive Oxidation Catalysts” Ind. Eng. Chem. Prod. Res. Dev. 15 169 1976
- Yao, Y.F. “The Oxidation of CO and Hydrocarbons over Noble Metal Catalysts” J. Catal. 87 152 1984
- Yao, H.C. Sieg, M. Plummer, H.K. “Surface Interactions in the Pt/Al 2 O 3 System” J. Catal. 59 365 1979
- Yao, H.C. Yao, Y.F. “Ceria in Automotive Exhaust Catalysts” J. Catal. 86 254 1984
- McCabe, R.W. Wong, C. Woo, H.S. “The Passivating Oxidation of Platinum” J. Catal. 114 354 1988