Effect of Sr on the properties of Ce-Zr-La mixed oxides

Ce-Zr-La-Sr mixed oxides, with different Sr contents, were prepared by the sol-gel method. In a flow-system microreactor, the reduction properties and the oxygen storage capacity (OSC) of the Ce-Zr-La-Sr mixed oxides were investigated by a temperature programmed reduction (TPR) and a pulse technique. It was shown that the properties of the Ce-Zr-La mixed oxides depend on the Sr content and that the optimum Sr content in the Ce-Zr-La-Sr mixed oxide is 3 mol%. The Ce-Zr-La-Sr mixed oxides doped with 3 mol% Sr (Ce0.52Zr0.4La0.05Sr0.03O1.945) has the largest specific surface area and better reduction properties and oxygen storage capacity in comparison to the other investigated samples. The XRD results of the Ce-Zr-La-Sr mixed oxides showed that their X-ray diffraction patterns are well in agreement with that of fluorite-type CeO2 with Sr ions incorporated into the Ce-Zr-La mixed oxide structures. With increasing calcination temperature, the intensity of the X-ray diffraction peaks increased, but no new peaks were observed. All of these indicate that the synthesized samples had good thermal stability.

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Synthesis and Characterization of CeO2-ZrO2-Al2O3 with High Thermal Stability and Oxygen Storage Capacity from Pseudoboehmite Precursor

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.463-464.160 ◽

2012 ◽

Vol 463-464 ◽

pp. 160-164

Author(s):

Dong Zhang

Keyword(s):

Thermal Stability ◽

Storage Capacity ◽

Oxygen Storage Capacity ◽

Oxygen Storage ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Alumina Oxide ◽

Composite Solid

The surface and structural properties, thermal stability and oxygen storage capability are inverstigated in ceria-zirconia-alumina oxide with deposition coprecipitation method using the Pseudoboehmite precursor. X-ray diffraction (XRD), Brunauer-Emmet Teller method (BET), Transmission electron microscopy (TEM) and oxygen pulsing technique are used to character the prepared materials. The prepared ceria-zirconia-alumina oxides are highly dispersed composite solid solution. After calcination at 650 °C and 1000 °C respectively, these compounds can still keep the structural and textural stability and hold excellent oxygen storage capability.

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Synthesis, Characterization and Study of the Photocatalytic Activity of the Ti/Fe Mixed Oxide

Journal of Advanced Oxidation Technologies ◽

10.1515/jaots-2014-0208 ◽

2014 ◽

Vol 17 (2) ◽

Author(s):

Franciély Ignachewski ◽

Eryza G. de Castro ◽

Fauze J. Anaissi ◽

Sérgio T. Fujiwara

Keyword(s):

Photocatalytic Activity ◽

Titanium Oxide ◽

Mixed Oxide ◽

Mixed Oxides ◽

Sol Gel ◽

X Ray Diffraction ◽

Gel Method ◽

X Ray ◽

Sol Gel Method

AbstractThe mixed oxides of Ti/Fe were prepared by sol-gel method and the materials were synthesized with different Ti/Fe ratios (0, 25, 50 and 75 wt% of iron). In the spectrum of the material without iron, it is possible to observe the predominant phase of the titanium oxide was anatase, which can be confirmed through x-ray diffraction. It can be observed that when the iron was added, the predominant phase of the titanium oxide was rutile and was found evidence of the formation of pseudobrookite (Fe

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Effect of Mg/Al molar ratio on the basicity of Mg-Al mixed oxide derived from Mg-Al hydrotalcite

Mediterranean Journal of Chemistry ◽

10.13171/mjc10602007021464sa ◽

2020 ◽

Vol 10 (6) ◽

pp. 625

Author(s):

Said Arhzaf ◽

Mohammed Naciri Bennani ◽

Sadik Abouarnadasse ◽

Hamid Ziyat ◽

Omar Qabaqous

Keyword(s):

Thermal Analysis ◽

Mixed Oxide ◽

Mixed Oxides ◽

Molar Ratio ◽

Acid Molecule ◽

X Ray Diffraction ◽

Phenol Adsorption ◽

X Ray ◽

Maximum Quantity ◽

Uv Visible

The fundamental character of the Mg-Al mixed oxide (Mgn(Al)O), derived from the Mg-Al hydrotalcite (MgnAl-CO3-HT), where n corresponds to the Mg/Al molar ratio (n: 2, 2.5, 3, 3.5 and 4), was studied by using the adsorption of phenol as a probe acid molecule. The hydrotalcite precursors were prepared by the coprecipitation method. Their derived mixed oxides were obtained by thermal treatment at 450°C in a flow of air. The resulting solids were characterized by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermogravimetric and differential thermal analysis (TG-DTA), nitrogen physisorption (BET) and phenol chemisorption. The phenol adsorption followed by UV-Visible spectrophotometry shows that the basicity increases with the Mg/Al molar ratio, such that maximum quantity of phenol adsorbed (Qads = 0.54 mmol/g cat) was obtained with the mixed oxide derived from the Mg-Al hydrotalcite of Mg/Al molar ratio equal to 3.5.

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Bulk Versus Surface Modification of Alumina with Mn and Ce Based Oxides for CH4 Catalytic Combustion

Materials ◽

10.3390/ma12111771 ◽

2019 ◽

Vol 12 (11) ◽

pp. 1771 ◽

Cited By ~ 2

Author(s):

Stefan Neatu ◽

Mihaela M. Trandafir ◽

Adelina Stănoiu ◽

Ovidiu G. Florea ◽

Cristian E. Simion ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Catalytic Combustion ◽

Mixed Oxides ◽

Sol Gel ◽

Nitrogen Adsorption ◽

X Ray Diffraction ◽

X Ray ◽

Temperature Programmed ◽

Catalytic Combustion Of Methane ◽

Adsorption Desorption

This study presents the synthesis and characterization of lanthanum-modified alumina supported cerium–manganese mixed oxides, which were prepared by three different methods (coprecipitation, impregnation and citrate-based sol-gel method) followed by calcination at 500 °C. The physicochemical properties of the synthesized materials were investigated by various characterization techniques, namely: nitrogen adsorption-desorption isotherms, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and H2–temperature programmed reduction (TPR). This experimental study demonstrated that the role of the catalytic surface is much more important than the bulk one. Indeed, the incipient impregnation of CeO2–MnOx catalyst, supported on an optimized amount of 4 wt.% La2O3–Al2O3, provided the best results of the catalytic combustion of methane on our catalytic micro-convertors. This is mainly due to: (i) the highest pore size dimensions according to the Brunauer-Emmett-Teller (BET) investigations, (ii) the highest amount of Mn4+ or/and Ce4+ on the surface as revealed by XPS, (iii) the presence of a mixed phase (Ce2MnO6) as shown by X-ray diffraction; and (iv) a higher reducibility of Mn4+ or/and Ce4+ species as displayed by H2–TPR and therefore more reactive oxygen species.

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Zr-Ce-Pr-O Mixed Oxide Phases with High Oxygen Storage Capacity (OSC)

Journal of the Japan Institute of Metals and Materials ◽

10.2320/jinstmet.73.262 ◽

2009 ◽

Vol 73 (4) ◽

pp. 262-267 ◽

Cited By ~ 1

Author(s):

Tadatoshi Murota ◽

Kosuke Sogawa ◽

Shinya Otsuka-Yao-Matsuo ◽

Takahisa Omata

Keyword(s):

Mixed Oxide ◽

Storage Capacity ◽

Oxygen Storage Capacity ◽

High Oxygen ◽

Oxygen Storage ◽

Oxide Phases ◽

High Oxygen Storage Capacity

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CO Oxidation over Pd Catalysts Supported on Different Supports: A Consideration of Oxygen Storage Capacity of Catalyst

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.347-353.3298 ◽

2011 ◽

Vol 347-353 ◽

pp. 3298-3301

Author(s):

Ye Xu ◽

Jin Qiang Ma ◽

Yuan Feng Xu ◽

Hui Li ◽

He Xing Li ◽

...

Keyword(s):

Co Oxidation ◽

Storage Capacity ◽

Oxygen Storage Capacity ◽

Oxygen Storage ◽

X Ray Diffraction ◽

Pd Catalysts ◽

Transmission Electron ◽

Pulse Experiment ◽

Temperature Programmed

A series of Pd catalysts supported on different materials (SiO2, γ-Al2O3, CeO2, TiO2) were synthesized through precipitation reduction of palladium ions with H2. They exhibited different activity during catalytic oxidation of CO to CO2. With the characterization of N2 physisorption experiment, X-ray diffraction, transmission electron microscopy, temperature-programmed reduction, and CO and O2 multi-pulse experiment, the correlation of catalytic activity and oxygen storage capacity (OSC) of catalyst has been investigated. It was found that the reactivity is largely controlled by the OSC of the catalysts, and thus Pd/CeO2 and Pd/TiO2 were more active than Pd/SiO2 and Pd/Al2O3 for CO oxidation.

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Structure and Oxygen Storage Capacity of Pr/Nd Doped CeO2—ZrO2 Mixed Oxides.

ChemInform ◽

10.1002/chin.200744010 ◽

2007 ◽

Vol 38 (44) ◽

Author(s):

Xiaodi Wu ◽

Xiaodong Wu ◽

Qing Liang ◽

Jun Fan ◽

Duan Weng ◽

...

Keyword(s):

Storage Capacity ◽

Mixed Oxides ◽

Oxygen Storage Capacity ◽

Oxygen Storage ◽

Doped Ceo2

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Pd/SiO2 Organic-Inorganic Hybrid Materials by Sol-Gel Method: Preparation and Thermal Stability under H2 Atmosphere

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1118.20 ◽

2015 ◽

Vol 1118 ◽

pp. 20-27

Author(s):

Jing Yang ◽

Bao Song Li ◽

Xiang Huo ◽

Hao Xu ◽

Hai Yun Hou

Keyword(s):

Thermal Stability ◽

Calcination Temperature ◽

Hybrid Materials ◽

Photoelectron Spectroscopy ◽

Sol Gel ◽

X Ray Diffraction ◽

Inorganic Hybrid ◽

X Ray ◽

Good Thermal Stability ◽

Pd Doping

Pd/SiO2 organic-inorganic hybrid materials were prepared by adding PdCl2 into methyl-modified silica sol. The Pd/SiO2 hybrid materials were characterized by X-ray diffraction (XRD), fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The effects of calcination temperature and Pd-doping on the phase transition of Pd element and the thermal stability of CH3 group in the Pd/SiO2 organic-inorganic hybrid materials were investigated. The results showed that the reduced metallic Pd0 exhibits good thermal stability under H2 atmosphere in the calcination process. Pd element in noncalcined Pd/SiO2 materials exists in PdCl2 form, calcination at 200 °C in a H2 atmosphere produces some metallic Pd0 and calcinations at 350 °C results in the complete transformation of Pd2+ to metallic Pd0. With the increase of calcination temperature, the Pd0 particle sizes increase and the hydrophobic Si−CH3 bands decrease in intensity. As the calcination temperature is greater than or equal to 350 °C, the loading of metallic Pd0 nearly has no influence on the chemical structure but, with the increase of Pd content, the formed Pd0 particle size increases. To keep the hydrophobicity of Pd/SiO2 membrane materials, the optimal calcination temperature is about 350 °C under H2 atmosphere.

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Oxygen Storage Capacity of CexZr1-xO2 (0.4≤x≤0.8) Solid Solution Using Thermogravimetric Analysis

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.747.579 ◽

2013 ◽

Vol 747 ◽

pp. 579-582 ◽

Cited By ~ 1

Author(s):

N. Shanmuga Priya ◽

Chandramohan Somayaji ◽

S. Kanagaraj

Keyword(s):

Solid Solution ◽

Storage Capacity ◽

Mixed Oxides ◽

High Surface ◽

High Surface Area ◽

Oxygen Storage Capacity ◽

Oxygen Storage ◽

Co Precipitation ◽

Good Number ◽

High Oxygen Storage Capacity

The property of high oxygen storage capacity (OSC) of Ceria is an important component in three-way catalysts (TWC), which depends on the low reduction temperature, high surface area and stable crystalline structure. These are required to be improved using mixed oxides for the increased OSC of TWC. Though a good number of literature is available in Ceria-Zirconia mixed oxides, optimization of the composition of oxides based on OSC is very much limited. Hence, an attempt was made to optimize the composition of CexZr1-xO2 (0.4 x 0.8) (CZ) based on the OSC using thermogravimetric technique. The CZ solid solution was prepared by co-precipitation (COP) method using Ceria nitrate, and Zirconia oxy-choloride precursors, where the freshly prepared metal hydroxide precipitates were continuously stirred at 45 °C for 60 minutes followed by washing and drying to obtain the nanosized CZ particles. The formation of single nanocrystallite with less than 8 nm size solid solution was identified by XRD, and the same was confirmed by Micro Raman studies. It is observed that the trend of OSC in CZ solid solution was based on the ratio of Ce to Zr in the starting aqueous solution, where the OSC was found to be maximum at 1.5 and the corresponding OSC of the compound was about 0.14 μmol per gram of Ceria.

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