This content is not included in your SAE MOBILUS subscription, or you are not logged in.
The Effect of De-Greening and Pre-Treatment on Automotive Catalyst Performance
ISSN: 0148-7191, e-ISSN: 2688-3627
Published September 11, 2011 by SAE International in United States
Annotation ability available
Computer simulation is now considered to be a crucial stage in the design of automotive catalysts due to the increasing complexity of modern aftertreatment systems. The resulting models almost invariably include surface reaction kinetics that are measured under controlled conditions similar to those found on a vehicle. Repeatability of the measurements used to infer surface reaction rates is fundamental to the accuracy of the resulting catalyst model. To achieve the required level of repeatability, it is necessary to ensure that the catalyst sample in question is stable and that its activity does not change during the test phase. It is therefore essential that the catalyst has been lightly aged, or "de-greened" before testing begins. It is also known that the state of the catalyst's surface prior to testing has an impact on its subsequent light-off performance and that test history can play an important role in catalyst activity. Suitably pre-treating the catalyst surface can ensure that a reference point is reached prior to a light-off test. The work summarized in this paper includes a study of both the de-greening phase and the state of the catalyst's surface on its activity, with the aim of developing a robust test protocol that provides repeatable kinetic data under realistic operating conditions.
To establish a protocol for initial stabilization of new catalyst samples, a series of tests were conducted on catalysts that had been thermally aged at 600°C and 750°C respectively until the sample exhibited stability. The activity of the sample was assessed by repeating identical CO light-off tests following each period of time in the oven. A period of 8 hours at 750°C was found to sufficiently stabilize the sample.
In the pre-treatment study, an investigation into the effect of several pre-treatment protocols on CO light-off was carried out on a three-way catalyst of commercial formulation in order to establish a robust protocol to ensure test repeatability. The investigation focused on pre-treating the catalyst sample in hydrogen, oxygen or nitrogen environments at specified conditions of flow and temperature. Following pre-treatment, identical CO light-off tests were performed in order to assess the respective influences of each pre-treatment. A trend of lower light-off temperatures was observed for all pre-treatment strategies on the first of two consecutive light-off temperature ramps with a notable increase in light-off temperature observed on the second ramp. As a result of this study a pre-treatment protocol was established. The protocol involves treating the catalyst sample in flowing nitrogen up to 600°C using a temperature ramp of 15°C/min.
CitationMcAtee, C., McCullough, G., Douglas, R., and Glover, L., "The Effect of De-Greening and Pre-Treatment on Automotive Catalyst Performance," SAE Technical Paper 2011-24-0188, 2011, https://doi.org/10.4271/2011-24-0188.
- Kaspar, J. Fornasiero, P. Hickey, N. “Automotive catalytic converters: current status and some perspectives,” Catalysis Today 77 419 449 2002 10.1016/S0920-5861(02)00384-X
- Olsson, L. Andersson, B. “Kinetic modelling in automotive catalysis,” Topics in Catalysis 28 89 98 2004 10.1023/B:TOCA.0000024337.50617.8e
- Samenfink, W. Albrodt, H. Frank, M. Gesk, M. et al. “Strategies to Reduce HC-Emissions During the Cold Starting of a Port Fuel Injected Gasoline Engine,” SAE Technical Paper 2003-01-0627 2003 10.4271/2003-01-0627
- Lafyatis, D.S. Ansell, G.P. Bennett, S.C. Frost, J.C. Millington, P.J. Rajaram, R.R. Walker, A.P Ballinger, T.H. “Ambient temperature light-off for automobile emission control,” Applied Catalysis B: Envir. 18 123 135 1998 10.1016/S0926-3373(98)00032-0
- Kubo, S. Yamamoto, M. Kizaki, Y. Yamazaki, S. et al. “Speciated Hydrocarbon Emissions of SI Engine during Cold Start and Warm-up,” SAE Technical Paper 932706 1993 10.4271/932706
- Kelly, K. Bailey, B. Coburn, T. Clark, W. et al. “Federal Test Procedure Emissions Test Results from Ethanol Variable-Fuel Vehicle Chevrolet Luminas,” SAE Technical Paper 961092 1996 10.4271/961092
- Benson, J. Koehl, W. Burns, V. Hochhauser, A. et al. “Emissions with E85 and Gasolines in Flexible/Variable Fuel Vehicles - The Auto/Oil Air Quality Improvement Research Program,” SAE Technical Paper 952508 1995 10.4271/952508
- Lupescu, J. Chanko, T. Richert, J. DeVries, J. “Treatment of Vehicle Emissions from the Combustion of E85 and Gasoline with Catalyzed Hydrocarbon Traps,” SAE Int. J. Fuels Lubr. 2 1 485 496 2009 10.4271/2009-01-1080
- Voltz, S.E. Morgan, C.R. Liederman, D. Jacob, S.M. “Kinetic Study of Carbon Monoxide and Propylene Oxidation on Platinum Catalysts,” Ind.Eng. Chem. Prod. Res. Develop. 12 4 294 301 1973 10.1021/i360048a006
- Torcrona, A. Skoglundh, M. Thormahlen, P. Fridell, E. Jobson, E. “Low temperature catalytic activity of cobalt oxide and ceria promoted Pt and Pd: -influence of pre-treatment and gas composition,” Applied Catalysis 14 131 146 1997 10.1016/S0167-2991(06)80965-1
- Yee, A. Morrison, S.J. Idriss, H. “A Study of the Reactions of Ethanol on CeO 2 and Pd/CeO 2 by Steady State Reactions, Temperature Programmed Desorption, and In Situ FT-IR,” Journal of Catalysis 186 279 295 1999 10.1006/jcat.1999.2563
- Holmgren, A. Azarnoush, F. Fridell, E. “Influence of pre-treatment on low temperature activity of Pt/ceria,” Applied Catalysis B: Envir. 22 49 61 1999 10.1016/S0926-3373(99)00033-8
- Burch, R. Millington, P.J. Walker, A.P. “Mechanism of the selective reduction of nitrogen monoxide on platinum based catalysts in the presence of excess oxygen,” Applied Catalysis B: Envir. 4 65 94 1994
- Bernal, S. Botana, F.J. Calvino, J.J. Cauqui, M.A. Cifredo, G.A. Jobacho, A. Pintado, J.M. Rodriguez-Izquierdo, J.M. “Microstructural and Chemical Properties of Ceria-Supported Rhodium Catalysts Reduced at 773K,” Journal of Physical Chemistry 97 4118 4123 1993 10.1021/jl00118a031
- Bernal, S. Calvino, J. Cifredo, G.A. Gatica, J.M. Perez Omil, J.A. Pintado, J.M. “Hydrogen Chemisorption on Ceria: Influence of the Oxide Surface Area and Degree of Reduction,” Journal of Catalysis 89 3499 3505 1993 10.1039/FT9938903499
- Golunski, S.E. Hatcher, H.A. Rajaram, R.R. Truex, T.J. “Origins of low-temperature three-way activity in Pt/CeO 2 ,” Applied Catalysis B: Envir. 5 367 376 1994 10.1016/0926-3373(94)00057-3