The alteration of the performance of field-aged Pd-based TWCs towards CO and C3H6 oxidation

Heo, Iljeong; Choung, Jin Woo; Kim, Pyung Soon; Nam, In−Sik; Song, Young-Yeal; In, Chi Bum; Yeo, Gwon Koo

doi:10.1016/j.apcatb.2009.07.016

Cited by 72 publications

(55 citation statements)

References 47 publications

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“…As shown in Table 2, both the BE of Pd 3d 5/2 and the surface atomic concentration of Pd decreased with the increasing aging temperature for all the Pd-containing catalysts examined, indicative of the alteration of the state of Pd from PdO to Pd 0 and the decline of the Pd dispersions, in consistency with the CO-chemisorption and H 2 -O 2 titration results presented in Table 1 and Table S3 of Supplementary Material [8]. The decline of the surface atomic concentration of Pd upon thermal aging was more severe on the Al 2 O 3 -based Pd(0.8)-600 catalysts than that on the perovskite-based catalysts such as Pd(0.8)/LaAlO 3 -600 and LaAlPd(0.8)O 3 -600 (Table 2).…”

Section: State Of Pdsupporting

confidence: 82%

“…In recent years, Pd has been used as an appropriate alternative for Pt in the modern commercial TWC system, mainly due to its cost advantage when combined with the use of unleaded and low-sulfur gasoline fuel [2]. Since TWCs are typically exposed to extremely high exhaust gas temperature, occasionally reaching to 1050°C and beyond, they are prone to be deactivated due to the sintering of the noble metals as well as the thermal degradation of other catalyst components including catalyst support, most commonly Al 2 O 3 [1,[4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Thermal stability of Pd-containing LaAlO3 perovskite as a modern TWC

Yoon

Kim

Lim

et al. 2015

Journal of Catalysis

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Section: State Of Pdsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Thermal stability of Pd-containing LaAlO3 perovskite as a modern TWC

Yoon

Kim

Lim

et al. 2015

Journal of Catalysis

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“…To understand the main cause for the deactivation of the Pd-only TWCs used under field-aging condition, Heo et al extensively examined the deactivation mechanism in view of the change of the physicochemical properties of the identical TWCs including the Pd dispersion and the level of contaminants. 13 Sintering of Pd was the dominant cause for the deactivation of the Pd-only TWC, while no systematic dependence of the content of the contaminants including sulfur (S) and lead (Pb) on the catalyst deactivation with respect to the catalyst mileage was observed. 11,15 CO chemisorption was then conducted to observe the trend of the alteration of the Pd MSA and particle size upon field-aging with respect to the catalyst mileage and the metal content for elucidating the change of the TWC activity of the Pd-only catalysts as a function of the Pd loading and catalyst mileage.…”

Section: ' Experimental Sectionmentioning

confidence: 98%

Activity Function for Describing Alteration of Three-Way Catalyst Performance over Palladium-Only Three-Way Catalysts by Catalyst Mileage

Kang

Kwon

Nam

et al. 2011

Ind. Eng. Chem. Res.

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A simple three-way catalyst (TWC) activity function based upon the alteration of the Pd metallic surface area (MSA) of Pd-only commercial monolith TWCs has been developed to describe the change of the catalytic performance with respect to the Pd metal loading varying from 5 to 10 g/L and the field-aged catalyst mileage from 4K (stabilized) to 98K miles. Particularly, the change of the Pd MSA of TWC with respect to the catalyst mileage has been well-correlated by the second-order sintering kinetics, regardless of the Pd content of the TWC. The TWC activity function was incorporated into the primary reaction kinetics developed for the stabilized 4K Pd-only TWCs to predict the deactivation of the Pd-only TWC performance with respect to the field-aged mileage. The overall reaction kinetic model with the TWC activity function developed in the present study is capable of describing the alteration of TWC performance with respect to the catalyst mileage, regardless of the catalyst metal content. ' INTRODUCTIONThe development of the catalyst activity function is useful for predicting the life of the catalyst for designing a commercial catalytic reactor, since more than 90% of the heterogeneous catalytic process experiences a decay of the reaction rate with respect to the reactor on-stream time. 1 The activity function can be obtained by correlating the rates at any time to time zero, although it requires exhaustive time and effort including the collection and test of the deactivated catalyst samples under practical operating conditions with respect to the duration of their uses. Another approach may be the independent development of an activity function based upon the alteration of the physicochemical properties of the catalyst including the content of the deactivation precursors, such as coke, sulfur, and contaminants, the metal dispersion, and the catalyst surface area. 2À4 The deactivation of the activity and durability of three-way catalyst (TWC) installed into gasoline driven cars is apparent as the catalyst mileage increases. 5 Furthermore, the technical and market demands for developing the deactivation model to predict the life of TWC becomes inevitable for the design of the TWC catalytic converter to meet the ever-tightening emission regulations throughout the world and the mileage guarantee by automakers. 6 However, a TWC activity function directly describing the alteration of TWC performance has been rarely reported, mainly due to the difficulty in collecting of the catalyst samples with respect to the catalyst mileage and the complexity of the deactivation of commercial TWC under the real driving condition.Ekstr€ om et al. predicted the decline of the catalytic activity of TWC aged under accelerated engine bench condition by the simple adjustment of the frequency factor of the rate constant included in the primary kinetics. 7 Baba et al. developed a TWC deactivation kinetics based upon the change of the frequency factor attributed to both sintering of Pt metal and phosphorus poisoning under accelerated engin...

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“…and 2.54 cm long) was installed in the reactor. Details of the reactor system are described elsewhere [16,17]. After pre-calcination of the catalyst sample in a stoichiometric feed condition (S = 1) at 450°C for 2 h, the TWC performance was examined with the ''full feed'' gas stream containing 1% CO, 500 ppm C 3 H 6 , 0.3% H 2 , 500 ppm NO, 1% O 2 , 10% CO 2 and 10% H 2 O in Ar balance (S = 1.17) [3,12,15].…”

Section: Reaction Systemmentioning

confidence: 99%