This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Cause and Effect of Reversible Deactivation of Diesel Oxidation Catalysts
Technical Paper
2014-01-1518
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
To meet TierII/LEVII emissions standards, light duty diesel (LDD) vehicles require high conversion efficiencies from the Aftertreatment Systems (ATS) for the removal of both Hydrocarbon (HC) and Nitrogen Oxide (NOx) species. The most populous configuration for LDD ATS have the Selective Catalytic Reduction (SCR) catalyst positioned on the vehicle behind the close coupled Diesel Oxidation Catalyst (DOC) and Catalyzed Diesel Particulate Filter (CDPF). This SCR position may require active heating measures which rely on the DOC/CDPF to provide heat through the combustion of HC and CO in the exhaust. Although DOCs are always impacted by their aging conditions, some aging conditions are shown to be both reversible and irreversible. Under continuous, high speed and high mileage conditions such as experienced in a modified Standard Road Cycle (SRC) or as it is better known, the High Speed Cycle (HSC), it is shown that the DOC's activity can deteriorate initially but significantly recover over repeated FTP-75 test cycles on fully aged catalysts. The stable, lean and hot environment experienced during these durability cycles, create a temporary condition on the PGM sites that can be reversed when the system is exposed to cooler, transient environment in the presence of additional reductant. This mechanism is similar to that experienced with lean NOx traps (LNT) under NOx regeneration conditions.1,2 Mechanisms of shifting PGM oxidation states have been observed in PdO containing methane oxidation when exposed to various thermal conditions3, 4, 5, 6. This phenomenon is successfully recreated under controlled laboratory settings utilizing both oven and engine aging methods. Furthermore, the performance of the aged catalyst was evaluated to highlight the re-activation of the catalyst for HC/CO and NO oxidation.
The advantage of using the HSC cycle is self-evident. The cycle's high speed allows the required 120k miles to be reached at a significantly shorter period of time, realizing substantial savings in time and program development costs. The harsher thermal environment of the cycle creates a worst case aging scenario that is discussed in this paper.
Recommended Content
Authors
Topic
Citation
Ahari, H., Zammit, M., Cattani, L., Jacques, J. et al., "Cause and Effect of Reversible Deactivation of Diesel Oxidation Catalysts," SAE Technical Paper 2014-01-1518, 2014, https://doi.org/10.4271/2014-01-1518.Also In
References
- West , B. , Huff , S. , Parks , J. , Lewis , S. et al. Assessing Reductant Chemistry During In-Cylinder Regeneration of Diesel Lean NOx Traps SAE Technical Paper 2004-01-3023 2004 10.4271/2004-01-3023
- Epling William S. , Campbell Larry E. , Yezerets Aleksey , Currier Neal W. , Parks James E. II Overview of the Fundamental Reactions and Degradation Mechanisms of NO x Storage/Reduction Catalysts Catalysis Reviews: Science and Engineering 46 2 163 245 2004
- Brogan , M. , Brisley , R. , Walker , A. , Webster , D. et al. Evaluation of NOx Storage Catalysts as an Effective System for NOx Removal from the Exhaust Gas of Leanburn Gasoline Engines SAE Technical Paper 952490 1995 10.4271/952490
- Wang Weicho , McCool Geoffrey , Kapur Neeti , Yuang Guang , Shan Bin , Nguyen Matt , Graham Uschi M. , Davis Burton H. , Jacobs Gary , Cho Kyeongjae , Hao Xianghong Mixed-Phase Oxide Catalyst Based On Mn-Mullite (Sm, Gd)Mn 2 O 5 for NO Oxidation in Diesel Exhaust Science 337 17 Aug. 2012
- Lassi , Ulla Deactivation Correlations of Pd/Rh Three-way Catalysts Designed for Euro IV Emission Limits: Effect of Ageing Atmosphere, Temperature And Time 951-42-6954-3
- Farrauto R.J. , Hobson M.C. , Kennelly T. , Waterman E.M. Catalytic chemistry of supported palladium for combustion of methane Appl. Catal. A: General 81 227 237 1992
- EPA 40 CFR Part 86, Appendix V
- EPA 40 CFR Part 86, Appendix VII
- Schleyer , C. , Eng , K. , Gorse , R. , Gunst , R. et al. Reversibility of Sulfur Effects on Emissions of California Low Emission Vehicles SAE Technical Paper 1999-01-1544 1999 10.4271/1999-01-1544
- Lyons , J. , Lax , D. , and Welstand , S. Investigation of Sulfur Sensitivity and Reversibility in Late-Model Vehicles SAE Technical Paper 1999-01-3676 1999 10.4271/1999-01-3676
- Gorse R.A. What Is All the Stink About Sulfur? Presentation - EPA In-Use Deterioration Workgroup January 14 1997
- Benson J.D. Fuel Sulfur - A Vehicle Emissions Issue Presentation - EPA In-Use Deterioration Workgroup January 14 1997
- Andersen , P. and Rieck , J. Advances in Pd Containing Three Way Catalyst Activity SAE Technical Paper 970739 1997 10.4271/970739