Thermal stability of a high surface area ceria under reducing atmosphere

Perrichon, V.; Laachir, A.; Abouarnadasse, Sadik; Touret, Olivier; Blanchard, G.

doi:10.1016/0926-860x(95)00089-5

Cited by 138 publications

(83 citation statements)

References 22 publications

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“…However, both FSPmade powders showed an excellent thermal stability when compared to commercial ceria which showed a pronounced loss in specific surface area for temperatures above 970 K. There, the mesoporous structure collapsed and the surface area decreased drastically. Perrichon et al 10 claimed that carbonate species stabilize the structure that collapses when they are eliminated at around 870 to 970 K. At this temperature, the FSP-made ceria powder preserved more than 60% (5Ce5) or 80% (8Ce3) of its initial surface area. Figure 11 shows a comparison with one of the best ceria in the literature prepared by a surfactant-assisted precipitation.…”

Section: B Thermal Stability Of Fsp-made Ceomentioning

confidence: 99%

“…11 along with those of a commercial powder (Rhône-Poulenc, Perrichon et al, 10 and a representative sample from the literature. 9 A nearly linear decrease of the A s was obtained for the FSP-made powders.…”

Section: B Thermal Stability Of Fsp-made Ceomentioning

confidence: 99%

“…The relative loss of surface area at temperatures as low as 1000 K is a general drawback of those methods. 10 This decrease in total surface area can be reduced by doping with transition metals like zirconium. 11 Recently mesoporous ceria of high specific surface area (200 m 2 /g) with improved resistance to sintering (40 m 2 /g at 1173 K) was made by a surfactantassisted precipitation.…”

Section: Introductionmentioning

confidence: 99%

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Flame-made Ceria Nanoparticles

2002

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Flame spray pyrolysis (FSP) has been used to synthesize high-surface-area ceria from cerium acetate in acetic acid solution. With the addition of an iso-octane/2-butanol mixture to that solution, homogeneous CeO 2 nanoparticles were obtained. The specific surface area of the powders ranged from 240 to 101 m 2 /g by controlling the oxygen dispersion and liquid precursor flow rates through the flame. Furthermore, for production rates from 2 to 10 g/h a constant average primary particle size could be obtained at selected process parameters. The ceria showed high crystallinity and primary particles with a stepped surface. The powder exhibited good thermal stability and conserved up to 40% of its initial specific surface area when calcinated for 2 h at 900°C. This shows the potential of FSP made ceria for high-temperature applications as in three-way catalysts or fuel cells.

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Section: B Thermal Stability Of Fsp-made Ceomentioning

confidence: 99%

Section: B Thermal Stability Of Fsp-made Ceomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Flame-made Ceria Nanoparticles

2002

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“…The ceria reflections of the catalyst are slightly narrower than those of the original support, suggesting that sintering occurred during the additional thermal aging, which is common for ceria in reducing environments. 44 This sintering likely led to the lowered specific surface area and pore volume of Pd/CeO 2 relative to that of CeO 2 (Table 1). Palladium species could not be detected by XRD analysis, suggesting it was highly dispersed over the support 45 and/or incorporated into the ceria framework.…”

Section: 2mentioning

confidence: 99%

Selective Hydrogenation of Phenol Catalyzed by Palladium on High-Surface-Area Ceria at Room Temperature and Ambient Pressure

et al. 2015

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Palladium supported on high-surface-area ceria effectively catalyzes the hydrogenation of phenol to cyclohexanone at atmospheric pressure and room temperature. Activation of H2 at Pd sites and phenol at surface ceria sites was investigated by probing the redox properties of the catalyst and studying the mechanism of phenol adsorption. Temperature-programmed reduction and pulsed chemisorption were used to examine the effects of prereduction temperature on catalyst dispersion and reducibility. A sharp effect of prereduction temperature on catalytic activity was observed. This dependence is rationalized as a result of interactions between palladium and ceria, which under reducing conditions enhance palladium dispersion and create different types of environments around the Pd active sites and of encapsulation of the catalyst caused by support sintering at high temperatures. Temperature-programmed diffuse reflectance infrared Fourier transform spectroscopy revealed that phenol undergoes dissociative adsorption on ceria to yield ceriumbound phenoxy and water. Reduction of the chemisorbed phenoxy species decreases the number of protonaccepting sites on the surface of ceria and prevents further dissociative adsorption. Subsequent phenol binding proceeds through physisorption, which is a less active binding mode for reduction by hydrogen. High activity can be restored upon regeneration of proton acceptor sites via reoxidation/reduction of the catalyst. ABSTRACT: Palladium supported on high-surface-area ceria effectively catalyzes the hydrogenation of phenol to cyclohexanone at atmospheric pressure and room temperature. Activation of H 2 at Pd sites and phenol at surface ceria sites was investigated by probing the redox properties of the catalyst and studying the mechanism of phenol adsorption. Temperature-programmed reduction and pulsed chemisorption were used to examine the effects of prereduction temperature on catalyst dispersion and reducibility. A sharp effect of prereduction temperature on catalytic activity was observed. This dependence is rationalized as a result of interactions between palladium and ceria, which under reducing conditions enhance palladium dispersion and create different types of environments around the Pd active sites and of encapsulation of the catalyst caused by support sintering at high temperatures. Temperature-programmed diffuse reflectance infrared Fourier transform spectroscopy revealed that phenol undergoes dissociative adsorption on ceria to yield cerium-bound phenoxy and water. Reduction of the chemisorbed phenoxy species decreases the number of proton-accepting sites on the surface of ceria and prevents further dissociative adsorption. Subsequent phenol binding proceeds through physisorption, which is a less active binding mode for reduction by hydrogen. High activity can be restored upon regeneration of proton acceptor sites via reoxidation/reduction of the catalyst.

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“…Cerium dioxide sinters at 700-800°C [3,4]. The most common way of enhancing the OSC and thermal stability of CeO 2 is by preparing its solid solution with ZrO 2 with a fluorite structure [5].…”

Section: Introductionmentioning

confidence: 99%

Thermally stable composite system Al2O3-Ce0.75Zr0.25O2 for automotive three-way catalysts

Alikin¹,

Bochkarev²,

Denisov³

et al. 2013

Catal. Ind.

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Abstract-Present day three way catalysts operate in contact with exhaust gases whose temperature is as high as >1000°C, so the problem of developing thermally stable catalytic compositions is still topical. A series of Al 2 O 3 -Ce 0.75 Zr 0.25 O 2 composites containing 0, 10, 25, and 50 wt % Al 2 O 3 has been synthesized by direct precipitation. The as prepared composites and those calcined in air at 1000 and 1100°C have been charac terized by BET, X ray diffraction, transmission electron microscopy, and temperature programmed reduc tion methods. The composites aged at 1050°C in a 2% O 2 + 10% H 2 O + 88% N 2 atmosphere have been used to prepare monolith catalysts, and the oxygen storage capacity (OSC) of the latter has been measured using a gas analysis setup. As the proportion of Al 2 O 3 in the composite is raised, the mixing uniformity and degree of dispersion of Ce x Zr 1 -x O 2 -δ particles increase, their chemical composition becomes homogeneous, and the amount of cerium involved in oxidation and reduction increases.

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Thermal stability of a high surface area ceria under reducing atmosphere

Cited by 138 publications

References 22 publications

Flame-made Ceria Nanoparticles

Flame-made Ceria Nanoparticles

Selective Hydrogenation of Phenol Catalyzed by Palladium on High-Surface-Area Ceria at Room Temperature and Ambient Pressure

Thermally stable composite system Al2O3-Ce0.75Zr0.25O2 for automotive three-way catalysts

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