Reduction of Exhaust Gas Emissions by Using Pd-based Three-way Catalysts

Lindner, D.; Lox, E.S.; Yperen, R. van; Ostgathe, K.; Kreuzer, Thomas

doi:10.4271/960802

Cited by 25 publications

(10 citation statements)

References 13 publications

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“…There are two major reasons for this renewed interest in palladium. First, PdO is by far the cheapest noble metal in the market for its ability to catalyze VOCs at significantly low temperature; second, to achieve faster light-off performance, Pd-based catalyst offer significant advantages over the traditional three-way catalysts [5][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

The Mechanism Studies of Ethanol Oxidation on PdO Catalysts by TPSR Techniques

et al. 2004

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The paper studies the direct oxidation of ethanol and CO on PdO/Ce 0.75 Zr 0.25 O 2 and Ce 0.75 Zr 0.25 O 2 catalysts. Characterization of catalysts is carried out by temperature-programmed desorption (TPD), temperature-programmed surface reaction (TPSR) techniques to correlate with catalytic properties and the effect of supports on PdO. The simple Ce 0.75 Zr 0.25 O 2 is in less active for ethanol and CO oxidation. After loaded with PdO, the catalytic activity enhances effectively. Combined the ethanol and CO oxidation activity with CO-TPD and ethanol-TPSR profiles, we can find the more intensive of CO 2 desorption peaks, the higher it is for the oxidation of CO and ethanol. Conversion versus yield plot shows the acetaldehyde is the primary product, the secondary products are acetic acid, ethyl acetate and ethylene, and the final product is CO 2 . A simplified reaction scheme (not surface mechanism) is suggested that ethanol is first oxidized to form intermediate of acetaldehyde, then acetic acid, ethyl acetate and ethylene formed going with the formation of acetaldehyde, acetic acid, ethyl acetate; finally these byproducts are further oxidized to produce CO 2 . PdO/Ce 0.75 Zr 0.25 O 2 catalyst has much higher catalytic activity not only for the oxidation of ethanol but also for CO oxidation. Thus the CO poison effect on PdO/Ce 0.75 Zr 0.25 O 2 catalysts can be decreased and they have the feasibility for application in direct alcohol fuel cell (DAFC) with high efficiency.

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Section: Introductionmentioning

confidence: 99%

The Mechanism Studies of Ethanol Oxidation on PdO Catalysts by TPSR Techniques

et al. 2004

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“…Palladium catalysts are used in different fields of petroleum refining such as the hydrofining process of fluidized catalytic cracking (FCC) or catalytic reforming [2], or in the reduction of acetylene to ethylene [3]. Another large-scale application with steadily growing importance is the introduction of palladium into modern automotive exhaust gas catalysts as an essential catalytic component of the 'washcoat' materials [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Electrical Contacts for n-Type Diamond

Teraji

Koizumi

Mita

et al. 1999

Jpn. J. Appl. Phys.

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The inelastic incoherent neutron scattering (IINS) technique has been utilized to study the way in which various kinds of palladium retain hydrogen after different pretreatments. Coldrolled palladium foil, coarse palladium powder and finely divided palladium samples of different particle size and pretreatment were compared after controlled hydrogenation at room temperature and subsequent short-term dehydrogenation at 20, 50 and 70 • C. In a set of experiments under constant conditions, the incomplete decomposition of the βand α-hydride phases at the given temperatures were found to be uncorrelated to the morphology of the samples under investigation or to the presence of strongly adherent carbonaceous degradation products at the surface of some of the samples. The dominant factor was the effect of hydrogen trapping due to mechanical pretreatment. It was shown that this effect may also be of some relevance at elevated temperatures.It was also found that IINS is a suitable technique for the analysis of strongly adherent carbons at the surface of metals and metal hydrides and to discriminate between simple molecular structures and organic species of extended size. This is even the case for partial coverage of finely divided powders, the strong electromagnetic absorption and high electrical conductivity raises problems in utilizing other analytical techniques.

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“…The catalyst is active at temperatures above 240 • C only. It is known that palladium-only catalyst shows inefficient NO x conversion [28][29][30]. The NO x reduction on the palladium-CeO 2 system occurs only at high temperatures.…”

Section: Low Temperature Activity Of Catalystmentioning

confidence: 99%