Oxygen Storage Capacity(OSC) and Active Oxygen Species of Alumina-Supported Nonstoichiometric Cerium Oxide Catalysts.

政明, 羽田; 生智, 水嶋; 範義, 角田; 晃史, 上野

doi:10.1246/nikkashi.1997.169

Cited by 9 publications

(5 citation statements)

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“…The CeO 2 - x species prepared acted as the active center for methane oxidation at 773 K and maintained the nonstoichiometric structure even after the reaction, indicating that the CeO 2 - x species were very stable in comparison with the others reported previously that were deactivated readily by the oxidation to the CeO 2 structure. − We supposed that the reversible oxygen activation occurs through the storage and release of oxygen in the CeO 2 - x lattice and that the oxygen species act as active species for methane oxidation according to 18 O 2 analyses . In addition, when Pd was present on CeO 2 - x , the deactivation in the direct NO decomposition was prolonged considerably in comparison with Pd on CeO 2 . Temperature-programmed desorption (TPD) spectra of oxygen suggested the spillover of oxygen species generated by the decomposition of NO on Pd.…”

Section: Introductionmentioning

confidence: 69%

“…15 In addition, when Pd was present on CeO 2-x , the deactivation in the direct NO decomposition was prolonged considerably in comparison with Pd on CeO 2 . 21 Temperature-programmed desorption (TPD) spectra of oxygen suggested the spillover of oxygen species generated by the decomposition of NO on Pd. This result contains important evidence for oxygen migration and/or diffusion between Pd and CeO 2-x , and thus, methane oxidation is expected to occur smoothly because of the synergistic effect between Pd and CeO 2-x compared with the case of CeO 2-x itself.…”

Section: Introductionmentioning

confidence: 99%

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Synergistic Effect between Pd and Nonstoichiometric Cerium Oxide for Oxygen Activation in Methane Oxidation

1998

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The catalytic behavior of activated oxygen on Pd/CeO2 - x /Al2O3 catalyst as well as the synergistic effect between Pd and nonstoichiometric cerium oxide has been revealed through methane oxidation by comparison with Pd catalysts such as Pd/CeO2/Al2O3, Pd/CeO2/SiO2, Pd/Al2O3, and Pd/SiO2 catalysts. The highest activity for methane oxidation was observed on the Pd/CeO2 - x /Al2O3 catalyst. This was ascribed to the deactivation of Pd, which was inhibited by the oxygen spillover from Pd to CeO2 - x , where the enhanced oxygen storage capacity (OSC) was observed by the nonstoichiometric structure and the oxygen species were reversibly stored/released in the presence of methane. Kinetics studies of methane oxidation resulted in it being first order with respect to methane and a half order with respect to oxygen for Pd/CeO2 - x /Al2O3 but nearly zero order with respect to oxygen for other catalysts. From temperature-programmed desorption (TPD), reduction (TPR), oxidation (TPO), and 18O tracer technique analyses, it was found that the oxygen species in Pd/CeO2 - x /Al2O3 behave reversibly, going from Pd to the lattice of cerium oxide by the spillover, and then are consumed on Pd in methane oxidation by the inverse spillover from cerium oxide. It is thus concluded that the high activity of oxygen activation on the Pd/CeO2 - x /Al2O3 catalyst is induced by both the nonstoichiometric structure of cerium oxide and Pd as the active center.

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Section: Introductionmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Synergistic Effect between Pd and Nonstoichiometric Cerium Oxide for Oxygen Activation in Methane Oxidation

1998

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“…The starting temperature in TPR curve was lowered with the decrease of the calcination temperatures while SA values increased as shown in Table 2. As stated by Haneda et al, 4) a diminution of particle size could lead to the increase of SA value and contribute to shift the oxygen release tempera ture towards lower temperature. The high SA powder is ex pected to have a higher rate of oxygen release, and also higher rate of oxygen storage.…”

Section: Samentioning

confidence: 82%

Oxygen Store and Release of CeO2-ZrO2-MO1.5 (M=La, Nd) Powders Prepared by Co-Precipitation Method

利雄

崇弘

隆

et al. 2004

J. Ceram. Soc. Japan

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¤¾@Éaeèì»µ½ CeO 2 ZrO 2 MO 1.5 (MLa, Nd) ²Ì_fÌzûúoÁ« JYEecOEá ²Þ Eåc¤vÞ aeêó³f»wHAE()C5590025 åãsZV]ae½Ñì 1638 Þ sH|@ÛåwH|w¨¿HwÈC6068585 ss ¶ae¼èäC¹¬ CeO 2 ZrO 2 MO 1.5 (MLa, Nd) powders to be used as three way catalysts for automotive exhaust gases were prepared from nitrate solutions by coprecipitation method. As a catalyst exposed to high temperature gas, a high thermal stability is required to keep high surface area. High oxygen storage capacity is also required. In this study, their oxygen storage capacity (OSC), surface area (SA) and temperature programmed reduction behav ior (TPR) of CeO 2 ZrO 2 MO 1.5 powders were measured. The substitution of ZrO 2 by MO 1.5 increased the OSC value at calcination temperature 1000 C. SA values decreased as the calcination temperature increased, and SA was suppressed by the addition of MO 1.5 . In both cases, the effect of LaO 1.5 addition was higher than that of NdO 1.5 .

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“…The granular products of ZrO2-MxOy system were pulverized to smaller than 20um in diameter by use of a pulverizer (Ika Co., LTD., LABLRTECHNK) with rotor speed of 5500rpm. Figure 6 and Table 2 4. CONCLUSIONS 95ZrO2-5MxOy(mol%) and 97wt% [20CeO2-80ZrO2 (mol%)]-3wt% MxOy powders were prepared by using group metal oxides MxOy to the ZrO2 or CeO2-ZrO2 system, and evaluated the influence of the additive oxides on the SA and OSC values.…”

Section: Introductionmentioning

confidence: 99%

“…(3) In the 95ZrO2-5MxOy (mol%) system, the powders containing Bi or transition metal oxides showed high (4) In the 97wt% (20CeO2-80ZrO2 (mol%)) 3wt%MxOy system, the addition of rare earth metal oxides to the powders resulted in increase of SA values after (5) In the 97wt% (2OCeO2-80ZrO2 (mol%)) 3wt%MxOy system, the addition of transition metal (Cr, Co, Ni, Cu, Ta) oxides resulted in increased OSC values of powder (6) It may be concluded that powders containing rare earth metals and those containing transition metals show high SA values and high OSC values, respectively.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Mixed Oxide Powders in the Systems ZrO2-MxOy and [20CeO2-80ZrO2(mol%)]-MxOy from Zirconium Sulfated Slurry for the Purification Catalysts of Automotive Emission

Nakatani

Wakita

Ota

et al. 2004

Journal of the Society of Materials Science, Japan

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Powders in the ZrO2-MxOy and [20CeO2-80ZrO2 (mol%)]-MxOy system were prepared from zirconium sulfated slurry. The components MxO are groups of metal oxides in the Periodic Table including transition and rare earth. The influence of MxOy addition on specific surface area (SA) and oxygen storage capacity (OSC) was investigated. It was found that, compared with additive-free powders, the powders containing La, Pr, Nd, Sm, Eu, Gd, Tb or Dy had high SA values at On the other hand, the powders containing V, Cr, Co, Ni or Cu had high It may be concluded that the powders containing rare earth metals show high SA values and those containing transition metals show high OSC values exhibiting high thermal stability.

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Oxygen Storage Capacity(OSC) and Active Oxygen Species of Alumina-Supported Nonstoichiometric Cerium Oxide Catalysts.

Cited by 9 publications

References 0 publications

Synergistic Effect between Pd and Nonstoichiometric Cerium Oxide for Oxygen Activation in Methane Oxidation

Synergistic Effect between Pd and Nonstoichiometric Cerium Oxide for Oxygen Activation in Methane Oxidation

Oxygen Store and Release of CeO2-ZrO2-MO1.5 (M=La, Nd) Powders Prepared by Co-Precipitation Method

Preparation of Mixed Oxide Powders in the Systems ZrO2-MxOy and [20CeO2-80ZrO2(mol%)]-MxOy from Zirconium Sulfated Slurry for the Purification Catalysts of Automotive Emission

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