Thermal gas treatment to regenerate spent automotive three-way exhaust gas catalysts (TWC)

Birgersson, Henrik; Eriksson, Lars; Boutonnet, Magali; Järås, Sven

doi:10.1016/j.apcatb.2004.09.001

Cited by 69 publications

(31 citation statements)

References 29 publications

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“…Sintering of noble metals has been widely investigated and the sintering rate of noble metals is largely dependent on the experimental conditions, e.g., substrate morphology, purities of catalyst species and support materials, composition of ageing atmospheres, temperature, and time [12][13][14][15][16][17]. In particular, ageing atmosphere in high temperature region was the key point for noble metal sintering through our experience.…”

Section: Sintering Behaviormentioning

confidence: 99%

Noble Metal Sintering Suppression Technology in Three-way Catalyst: Automotive Three-way Catalysts with the Noble Metal Sintering Suppression Technology Based on the Support Anchoring Effect

Shinjoh

2009

Catal Surv Asia

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Section: Sintering Behaviormentioning

confidence: 99%

Noble Metal Sintering Suppression Technology in Three-way Catalyst: Automotive Three-way Catalysts with the Noble Metal Sintering Suppression Technology Based on the Support Anchoring Effect

Shinjoh

2009

Catal Surv Asia

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“…4), 5) It is also known that such agglomeration and sintering of a metal become pronounced with an increase in the concentration of the metal. In order to provide against such catalyst deactivation, excess precious metals have to be loaded despite the high cost.…”

Section: Introductionmentioning

confidence: 99%

Thermally stable Pt-Al2O3 cryogel with high platinum concentration for catalytic combustion

Osaki

Yamada

Tajiri

2008

J. Ceram. Soc. Japan

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The alumina cryogel with 5 mass platinum was prepared from aluminum sec-butoxide and H 2 PtCl 6 through the sol-gel processing and subsequent freeze drying. The cryogel showed higher thermal stability of platinum than the corresponding xerogel and impregnation catalysts at elevated temperatures. Also for the catalytic VOC combustion the cryogel exhibited higher activity than other catalysts. It was revealed that about half of the platinum surface was inside the alumina cryogel, and such encapsulation was considered the principal cause for the higher stability. 2008 The Ceramic Society of Japan. All rights reserved.Key-words : Cryogel, Sol-gel, Freeze drying, Platinum, Alumina, Catalytic combustion, Thermal stability, Dispersion, VOC [Received November 2, 2007; Accepted January 17, 2008] 1. Introduction As growing the demands for global environmental protection, much attention has been paid to the performance of a catalyst for exhaust emission control.1) Platinum is one of the important elements used for purifying the harmful emissions.2),3) However it is known that a precious metal agglomerates and sinters easily at high temperatures, decreasing the surface area of the metal, which results in catalyst deactivation. 4),5) It is also known that such agglomeration and sintering of a metal become pronounced with an increase in the concentration of the metal. In order to provide against such catalyst deactivation, excess precious metals have to be loaded despite the high cost. In our previous studies, the sol-gel processing and subsequent freeze drying, bringing about cryogel, successfully improved the stability of platinum (0.5 mass) on alumina at elevated temperatures. 6),7) In the present studies, platinum-alumina cryogel with high platinum concentration (5 mass) was prepared, and the thermal stability and catalytic combustion activity were examined in comparison to those of the corresponding xerogel and two impregnation catalysts using alumina cryogel and commercial alumina as the supports.

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“…The interest in finding suitable in situ regeneration methods of commercial TWCs has recently grown. The use of liquid solvents, such as weak organic acids (e.g., acetic, oxalic and citric acids) for extraction of contaminants has been reported [11,12], as well as the application of various thermo-chemical treatments using O 2 , H 2 and Cl-containing gas mixtures [13,14] or other Cl-containing reagents (e.g., 1,2-dichloropropane) [15] for the redispersion of large noble metal particles.…”

Section: Introductionmentioning

confidence: 99%

Efficient In-Situ Regeneration Method of the Catalytic Activity of Aged TWC

Christou

Efstathiou

2007

Top Catal

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The expansion of durability of deactivated ''three-way'' catalysts (TWCs) used in gasoline-driven cars by applying efficient, economically viable and environmentally friendly methods for the in situ regeneration of their performance to acceptable levels was investigated. New experimental results on the use of a weak oxalic acid washing solution as a means of an efficient regeneration method of a severely aged (83,000 km mileage) commercial TWC are presented. Oxalic acid is shown to be the most efficient extracting agent of phosphorus, a severe poison of TWCs, among acetic acid, citric acid, NTA and EDTA investigated. X-ray diffraction studies provided strong evidence that washing of the aged TWC results in the removal of CePO 4 , AlPO 4 and (Mg,Ca,Zn) 3 (PO 4 ) 2 type phosphates leading to a significant increase of BET area and pore volume, as well as of CO and NO conversions (catalytic activity tests). The latter is strongly related with the increase in the number of active catalytic sites, as illustrated by in situ DRIFTS studies, after opening closed pores and uncovering additional catalyst surface.

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Thermal gas treatment to regenerate spent automotive three-way exhaust gas catalysts (TWC)

Cited by 69 publications

References 29 publications

Noble Metal Sintering Suppression Technology in Three-way Catalyst: Automotive Three-way Catalysts with the Noble Metal Sintering Suppression Technology Based on the Support Anchoring Effect

Noble Metal Sintering Suppression Technology in Three-way Catalyst: Automotive Three-way Catalysts with the Noble Metal Sintering Suppression Technology Based on the Support Anchoring Effect

Thermally stable Pt-Al2O3 cryogel with high platinum concentration for catalytic combustion

Efficient In-Situ Regeneration Method of the Catalytic Activity of Aged TWC

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