Modification of the Redox Behaviour of CeO2Induced by Structural Doping with ZrO2

Fornasiero, Paolo; Balducci, Gabriele; Monte, R. Di; Kašpar, Jan; Sergo, Valter; Gubitosa, G.; Ferrero, Alejandro; Graziani, M.

doi:10.1006/jcat.1996.0373

Cited by 694 publications

(459 citation statements)

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“…In recent years, it has been found that cerium oxide containing zirconium oxide is much better than pure ceria for catalytic oxidation, due to the doping of Zr into CeO 2 increasing the oxygen mobility in the bulk of mixed oxide thus improving its oxygen storage capacity, enhancing its redox properties as well as thermal stability [13][14][15][16][17]. It is shown that Ce 0.75 Zr 0.25 O 2 solid solution, which was derived by solgel route, released oxygen at much lower temperature than that prepared by the solid-state reaction [15].…”

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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“…The reducibility of the different catalysts was studied by temperature- exhibites reduction peaks at 760 and 1050 K, which can be attributed to surface and bulk reduction processes, respectively [25,28,29]. Pt addition to the CeO 2 support produced important changes in the TPR profiles.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

“…Pt addition to the CeO 2 support produced important changes in the TPR profiles. It is well known that cerium oxide reduction involves several processes: (i) the removal of surface carbonates [29], (ii) a change in the cerium oxidation state (Ce(IV) to Ce(III)) and (iii) -OH group formation by spillover of atomic hydrogen from Pt [28,29]. Furthermore, the surface reduction of ceria was shifted to lower temperatures in the presence of Pt [25].…”

Section: Catalyst Characterizationmentioning

confidence: 99%

Influence of the metal precursor on the catalytic behavior of Pt/Ceria catalysts in the preferential oxidation of CO in the presence of H2 (PROX)

Jardim

Rico-Francés

Coloma

et al. 2015

Journal of Colloid and Interface Science

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The effect of the metal precursor (presence or absence of chlorine) on the preferential oxidation of CO in the presence of H2 over Pt/CeO2 catalysts has been studied. The catalysts were prepared using (Pt(NH3)4)(NO3)2 and H2PtCl6, as precursors, in order to ascertain the effect of the chlorine species on the chemical properties of the support and on the catalytic behavior of these systems in the PROX reaction. The results show that chloride species exert an important effect on the redox properties of the oxide support due to surface chlorination. Consequently, the chlorinated catalyst exhibits a poorer catalytic activity at low temperatures compared with the chlorine-free catalyst, and this is accompanied by a higher selectivity to CO2 even at high reaction temperatures. It is proposed that the CO oxidation mechanism follows different pathways on each catalyst. This is a previous version of the article published in Journal of Colloid and Interface Science. 2015, 443: 45-55. doi:10.1016/j.jcis.2014 3: Graphical Abstract (for review)• The presence or absence of Cl in the Pt precursor strongly affects the catalytic behavior.• The Pt precursor affects the PROX mechanism at low reaction temperatures.• At 333 K, the mechanism in the Cl-free catalyst seems to involve the -OH groups on the support.• At higher temperatures, the reaction occurs via the same mechanism on both catalysts.. Highlights (for review) AbstractThe effect of the metal precursor (presence or absence of chlorine) on the preferential oxidation of CO in the presence of H 2 over Pt/CeO 2 catalysts has been studied. The catalysts are prepared using (Pt(NH 3 ) 4 )(NO 3 ) 2 and H 2 PtCl 6 , as precursors, in order to ascertain the effect of the chlorine species on the chemical properties of the support and on the catalytic behavior of these systems in the PROX reaction. The results show that chloride species exert an important effect on the redox properties of the oxide support due to surface chlorination. Consequently, the chlorinated catalyst exhibits a poorer catalytic activity at low temperatures compared with the chlorine-free catalyst, and this is accompanied by a higher selectivity to CO 2 even at high reaction temperatures. It is proposed that the CO oxidation mechanism follows different pathways on each catalyst.

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“…These observations can be explained as being due to desorption of O 2 from the ceria containing materials (and the concomitant formation of Ce 3+ ) [16][17][18][19][20][21][22][23]. Initially this O 2 (rather than leaving the system) reacted with the PM and formed CO 2 .…”

Section: Formation Of Ce 3+ -Co Species From Reaction Between Cexzr1-mentioning

confidence: 99%

“…The rationale behind the use of these materials in this reaction is related to the oxygen storage capacity of the catalysts. CeO 2 can desorb and re-adsorb O 2 through formation and consumption of a Ce 2 O 3 oxide [16][17][18][19][20]. The oxygen atoms involved in this process are active for promotion of various combustion and reforming reactions [21][22][23][24][25] and for this reason (as well as their ability to dampen excursions to overly fuel rich or fuel lean exhaust conditions) Ce (x) Zr (1-x) O 2 catalysts are used as supports in many catalytic formulations.…”

Section: Introductionmentioning

confidence: 99%

Attempts at an in situ Raman study of ceria/zirconia catalysts in PM combustion

Sullivan

Dulgheru

Atribak

et al. 2011

Applied Catalysis B: Environmental

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Publisher's statementThis is the author's version of a work that was accepted for publication in Applied Catalysis B: Environmental. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Applied Catalysis B: Environmental, 108-109 (1) Ce (x) Zr (1-x) O 2 catalysts with various Ce / Zr contents were studied using Raman spectroscopy under different gaseous atmospheres, at different temperatures and in the presence of a model soot.Catalysts with high concentrations of Zr fluoresced at elevated temperatures making analysis of their spectra impossible. This effect became even more pronounced at higher temperatures. CeO 2 and solid solutions with relatively low concentrations of Zr showed a red shift and a decrease in intensity of the characteristic F 2g peak at high temperatures under different atmospheres. The magnitude of the latter effect was higher under reducing atmospheres. These changes are reversible upon cooling, showing that they relate to a lattice expansion effect rather than any major chemical change to the material. In the presence of the model soot the Raman spectra of all materials was much decreased due to the absorption of the incident and scattered radiation by the soot particles. The presence of soot does not change the relative intensities or positions of the peaks in the spectra of the solid solutions. Evidence is shown for the production of a Ce 3+ -CO species following interaction between the soot and the surface at high temperature in an inert atmosphere.

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Modification of the Redox Behaviour of CeO2Induced by Structural Doping with ZrO2

Cited by 694 publications

References 1 publication

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

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

Influence of the metal precursor on the catalytic behavior of Pt/Ceria catalysts in the preferential oxidation of CO in the presence of H2 (PROX)

Attempts at an in situ Raman study of ceria/zirconia catalysts in PM combustion

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