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Performance Characterisation of a Range of Diesel Oxidation Catalysts: Effect of Pt:Pd Ratio on Light Off Behaviour and Nitrogen Species Formation
Technical Paper
2011-24-0193
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Understanding the behavior of automotive catalysts formulations under the wide range of conditions characteristic of automotive applications is key to the design of present and future emissions control systems. Platinum-based oxidation catalysts have been in use for some time to treat the exhaust of diesel-powered vehicles and have, as part of an emissions control package, successfully enabled compliance with emissions legislation. However, progressively stringent legislated limits, coupled with the need to reduce vehicle manufacturing costs, is incessantly demanding the development of new and improved catalyst formulations for the removal of pollutants in the diesel exhaust. With the introduction of low sulfur diesel fuel, and the advantageous decline in Palladium prices with respect to Platinum, bimetallic Pt:Pd-based catalysts have found an application in diesel after treatment. In this paper the findings of a study carried out on a range of lightly loaded (40 g/ft₃) diesel oxidation catalysts with varying Pt:Pd ratios are presented. The catalysts' performance characterization was measured on a state-of-the-art, commercially available, integral synthetic gas reactor and a range of exhaust analyzers was used to speciate the exhaust gas on catalyst exit. The aim of the study was to determine the effect of the Pt:Pd ratio on catalyst performance. The evaluation of the impact of varying the formulation on catalyst light-off and nitrogen species formation was of particular interest to support both catalyst modeling and exhaust system design. The study found that, at parity of exhaust flow conditions tested, the same nitrogen species are evolved in all of the catalysts, although in different concentrations. Higher Pt content distinctly favors higher conversion of NO to NO₂, which is beneficial if further treatment by LNT or SCR is implemented. Higher Pt content however, also promotes higher N₂O formation, which is undesirable. The effect on other nitrogen species of interest from an emissions control standpoint, namely NH₃ and N₂, is a more complex function of test conditions. Higher Pd content generally lowers the mixture CO catalyst light-off temperature, driven by higher metal activity towards CO conversion, which is highly desirable for the treatment of diesel exhaust gas. However, the performance of samples with higher Pd content appears to be affected by oxygen exposure. The effect on HC conversion is a more complex function of catalyst composition and reacting mixture, with CO concentration playing an important role on the overall catalyst performance.
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Glover, L., Douglas, R., McCullough, G., Keenan, M. et al., "Performance Characterisation of a Range of Diesel Oxidation Catalysts: Effect of Pt:Pd Ratio on Light Off Behaviour and Nitrogen Species Formation," SAE Technical Paper 2011-24-0193, 2011, https://doi.org/10.4271/2011-24-0193.Also In
References
- BASF http://www.catalysts.basf.com/Main/mobile_emissions/mobile_sources/automotive_emissions/diesel_automobiles.be 08 Feb 2011
- Matthey, Johnson http://ect.jmcatalysts.com/emission-control-technologies-catalysts 08 Feb 2011
- Topsoe http://www.topsoe.com/business_areas/automotive/catalysts.aspx 08 Feb 2011
- Irani, K Epling, W S Blint, R “Effect of hydrocarbon species on no oxidation over diesel oxidation catalysts” Applied Catalysis B: Environmental 92 422 428 2009
- Majewski, W. Khair, M. “Diesel Emissions and Their Control,” SAE International Warrendale, PA 978-0-7680-0674-2 2006 10.4271/R-303
- Burch, R “Knowledge and Know-How in Emission Control for Mobile Applications” Catalysis Reviews 46 3 271 334 2004
- Matthey, Johnson Platinum 2009, Palladium Use in Diesel Oxidation Catalyst http://www.platinum.matthey.com/publications/pgm-market-reviews/archive/platinum-2009/Pt2009.html 2009
- Burch, R Millington, P J “Selective reduction of nitrogen oxides by hydrocarbons under lean-burn conditions using supported platinum group metal catalysts” Catalysis Today 26 185 206 1995
- Burch, R Watling, T C “Kinetics of the Reduction of NO by C 3 H 6 and C 3 H 8 Over Pt Based Catalysts Under Lean-Burn Conditions” Studies in Surface Science and Catalysis 116 199 212 1997
- UK Environment Agency http://www.environment-agency.gov.uk/business/topics/pollution/440.aspx 08 Feb 2011
- US. Environmental Protection Agency Greenhouse Gas Reporting Rule, 40 CFR Part 86 87 and 89 http://www.epa.gov/climatechange/emissions/ghg_infosheets.html
- Yao, Y-F Y “Oxidation of Alkanes over Noble Metal Catalysts” Ind. Eng. Chem. Prod. Res. Dev. 19 293 298 1980
- Yao, Y-F Y “The Oxidation of CO and Hydrocarbons over Noble Metal Catalysts” Journal of Catalysis 87 152 162 1984
- Patterson, M J Angive, D E Cant, N W “The effect of carbon monoxide on the oxidation of four C6 to C8 hydrocarbons over platinum, palladium and rhodium” Applied Catalysis B: Environmental 26 47 57 2000
- Ansell, G.P. Bennett, P.S. et al. “The development of a model capable of predicting lean NOx catalyst performance under transient conditions” Applied Catalysis B: Environmental 10 183 201 1996
- Morlang, A. et al. “Bimetallic Pt/Pd diesel oxidation catalysts - Structural characterization and catalytic behavior” Applied Catalysis B: Environmental 60 191 199 2005
- Kaneeda, M. Iizuka, H. Hiratsuka, T. Shinotsuka, N. Arai, M. “Improvement of thermal stability of NO oxidation Pt/A12O3 catalyst by addition of Pd” Applied Catalysis B: Environmental 90 564 569 2009
- Han, M Assanis, D Bohac, S “Characterization of heat-up diesel oxidation catalysts through gas flow reactor and in-situ engine testing” Proc. IMechE Vol. 222 Part D: J. Automobile Engineering
- van Basshuysen, R. Schäfer, F. “Internal Combustion Engine Handbook,” SAE International Warrendale, PA 978-0-7680-1139-5 2004 10.427l/R-345
- Jemma, C.A. Shore, P.R. Widdicombe, K.A. “Analysis of C1-C16 Hydrocarbons Using Dual-Column Capillary GC: Application to Exhaust Emissions from Passenger Car and Motorcycle Engines” Journal of Chromatographic Science 33 1 34 48 1995
- Bohac, S. Han, M. Jacobs, T. López, A. et al. “Speciated Hydrocarbon Emissions from an Automotive Diesel Engine and DOC Utilizing Conventional and PCI Combustion,” SAE Technical Paper 2006-01-0201 2006 10.4271/2006-01-0201
- Sampara, C S Bissett, E J Chmielewski§, M “Global Kinetics for a Commercial Diesel Oxidation Catalyst with Two Exhaust Hydrocarbons” Ind. Eng. Chem. Res. 47 311 322 2008
- Hauff, K Tuttlies, U Eigenberger, G Nieken, U “A global description of DOC kinetics for catalysts with different platinum loadings and aging status” Applied Catalysis B: Environmental 100: 10 18 2011
- Burch, R Millington, P J Walker, A P “Mechanism for the selective reduction of nitrogen monoxide on platinum-based catalysts in the presence of excess oxygen” Applied Catalysis B: Environmental 4 65 94 1194
- Haaβ, F Fuess, H “Structural Characterization of Automotive Catalysts” Advanced Engineering Materials 7 899 913 2005
- Bathia, D McCabe, R W Harold, M P Balakotaiah, V “Experimental and kinetic study of NO oxidation on model Pt catalysts” Journal of Catalysis 2009
- Kikuyama, S et al. “A role of components in Pt-ZrO2/A12O3 as a sorbent for removal of NO and NO 2 ” Applied Catalysis A: General 226 23 30 2002