Thermal Deactivation of a Three-Way Catalyst: Changes of Structural and Performance Properties

Stenbom, Bertil; Smedler, Gudmund; Nilsson, Per H.; Lundgren, Staffan; Wirmark, G.

doi:10.4271/900273

Cited by 17 publications

(7 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The catalyst of a family car can contain approximately 1.75 g of metals, according to Barefoot (1997), seen in Morton et al (2001). Stenbom et al (1990) analyzed a new and an old catalyst using TEM/EDX microscopy. They reported a uniform distribution of PGEs on the surface of the new catalyst; this even distribution of PGEs was not observed on the old catalyst surface.…”

Section: Introductionmentioning

confidence: 99%

Platinum group elements study in automobile catalysts and exhaust gas samples

Omrani

Goriaux

Liu

et al. 2020

Environmental Pollution

View full text Add to dashboard Cite

Section: Introductionmentioning

confidence: 99%

Platinum group elements study in automobile catalysts and exhaust gas samples

Omrani

Goriaux

Liu

et al. 2020

Environmental Pollution

View full text Add to dashboard Cite

“…The appearance of this peak can be linked to the effects of ageing: the high temperature sintering of these components hindered the Ce 4+ to Ce 3+ redox reaction [34]. In addition, there may be a contribution of chemical ageing, with Ce reacting with the phosphate compound present in the engine out gas, coming from the combustion of engine oil additives, forming the very stable CePO4 phase [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. These effects lead to immobilization of Ce, hindering its participation to redox reactions necessary for oxygen storage.…”

Section: Ftir Surface Characterization Of the Metal Particles And Of mentioning

confidence: 99%

“…The development of laboratory ageing protocols for automotive catalysts, able to overcome the limitations of accelerated engine bench tests, ensuring a better correlation with real on-vehicle ageing requires a deep knowledge of catalyst behavior in working condition during its entire useful life. Numerous studies have investigated this correlation on ad-hoc prepared catalysts [18][19][20][21], with the limitation that no on-vehicle data can be collected for these systems.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the Evolution of Noble Metal Particles in a Commercial Three-Way Catalyst: Correlation between Real and Simulated Ageing

et al. 2021

View full text Add to dashboard Cite

Ageing of automotive catalysts is associated to a loss of their functionality and ultimately to a waste of precious resources. For this reason, understanding catalyst ageing phenomena is necessary for the design of long lasting efficient catalysts. The present work has the purpose of studying in depth all the phenomena that occur during ageing, in terms of morphological modification and deactivation of the active materials: precious metal particles and oxidic support. The topic was deeply investigated using specific methodologies (FT-IR, CO chemisorption, FE-SEM) in order to understand the behavior of metals and support, in terms of their surface properties, morphology and dispersion in the washcoat material. A series of commercial catalysts, aged in different conditions, have been analyzed, in order to find correlations between real and simulated ageing conditions. The characterization highlights a series of phenomena linked to the deactivation of the catalysts. Pd nanoparticles undergo a rapid agglomeration, exhibiting a quick loss of dispersion and of active sites with an increase of particles size. The evolution of the support allows highlighting also the contribution of chemical ageing effects. These results were also correlated with performance tests executed on synthetic gas bench, underlining a good correspondence between vehicle and laboratory aged samples and the contribution of chemical poisoning to vehicle aged ones. The collected data are crucial for the development of accelerated laboratory ageing protocols, which are instrumental for the development and testing of long lasting abatement systems.

show abstract

“…There are many independent processes that collectively contribute to catalyst deactivation [l, 21, the most important of which are chemical and thermal mechanisms. Chemical deactivation mechanisms primarily consist of constituent poisoning and surface glazing (Zn-, Ca-, and/or Pcontaining phases) [3, 41, whereas thermal deactivation will result in microstructural changes in the washcoat constituents, including the precious metals [5,6]. These thermally-induced microstructural effects include sintering, alloying, particle size changes, phase transformations, and constituent interactions.…”

Section: Introductionmentioning

confidence: 99%

“…While there are a plethora of bulk microstructural characterization techniques available, such as X-ray photoelectron spectroscopy and X-ray diffraction, only a few techniques, primarily transmission electron microscopy (TEM), are capable of providing the type of atomic resolution necessary for ultimate catalyst characterization. Although there have been several significant microscopy studies performed on "model" catalyst systems [7,8], there has been only limited work done on actual automotive catalysts [6,9,10], primarily due to the difficulty in preparing representative samples for TEM examination [ 111. In order to better understand the effect of aging on the catalyst, it is important to study the intact washcoat structure (as opposed to scraped, thus mixed, powders).…”

Section: Introductionmentioning

confidence: 99%

Thermally-Induced Microstructural Changes in a Three-Way Automotive Catalyst

Kenik

Coffey

et al. 1997

SAE Technical Paper Series

View full text Add to dashboard Cite

The use of advanced electron microscopy techniques to characterize both the bulk and near-atomic level microstructural evolution of catalyst materials during different dynamometer/vehicle aging cycles is an integral part of understanding catalyst deactivation. The study described here was undertaken to evaluate thermallyinduced microstructural changes which caused the progressive loss of catalyst performance in a three-way automotive catalyst.Several different catalyst processing variables, for example changing the washcoat ceria content, were also evaluated as a function of aging cycle and thermal history. A number of thermallyinduced microstructural changes were identified using high resolution electron microscopy techniques that contributed to the deactivation of the catalyst, including sintering of all washcoat constituents, y-alumina transforming to a-, p-, and &alumina, precious metal redistribution, and constituent encapsulation. The data accumulated in this study have been used to correlate microstructural evolution with thermal history and catalyst performance during various aging cycles and to subsequently evaluate different washcoat formulations for increased thermal stability.

show abstract

Thermal Deactivation of a Three-Way Catalyst: Changes of Structural and Performance Properties

Cited by 17 publications

References 14 publications

Platinum group elements study in automobile catalysts and exhaust gas samples

Platinum group elements study in automobile catalysts and exhaust gas samples

Characterization of the Evolution of Noble Metal Particles in a Commercial Three-Way Catalyst: Correlation between Real and Simulated Ageing

Thermally-Induced Microstructural Changes in a Three-Way Automotive Catalyst

Contact Info

Product

Resources

About