Unusual Redox Properties of Bismuth in Sol–Gel Bi-Mo-Ti Mixed Oxides

1998 ◽  
Vol 177 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Jan-Dierk Grunwaldt ◽  
Manuel D. Wildberger ◽  
Tamas Mallat ◽  
Alfons Baiker
Keyword(s):  
Mixed Oxides ◽  
Sol Gel ◽  
Redox Properties

Effect of Complexing Agent on Morphology and Crystal Structure of La1-xCexCoO3 (x=0, 0.2, and 0.4) Perovskite-Type Mixed Oxides Catalyst Prepared by Sol-Gel Method

2010 ◽  
Vol 658 ◽  
pp. 29-32 ◽  
Author(s):  
Kanit Soongprasit ◽  
Duangdao Aht-Ong ◽  
Viboon Sricharoenchaikul ◽  
Duangduen Atong
Keyword(s):  
Crystal Structure ◽  
Polyvinyl Alcohol ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Value Added ◽  
Molar Ratio ◽  
Complexing Agent ◽  
Nitrate Hexahydrate ◽  
Mixed Oxide Catalysts ◽  
Perovskite Type

. La1-xCexCoO3 (x=0, 0.2, and 0.4) perovskite-type mixed oxides using polyvinyl alcohol (PVA) as complexing agent at two molar ratio of metal ion to PVA (1:1 and 1:2) were successfully prepared by sol-gel process. The precursor included lanthanum (II) nitrate hexahydrate, cerium (II) nitrate hexahydrate, and cobalt (II) nitrate hexahydrate where polyvinyl alcohol was added as complexing agent. The suitable condition of Cerium (Ce) substitution and PVA molar ratio were established for further application in hydrocarbon conversion to high value added products. TGA thermogram of as-prepared precursor showed that PVA absolutely decomposed at temperature higher than 500°C. XRD patterns of calcined catalyst showed both LaCoO3 rhombohedral and CeO2 cubic structures that confirmed the formation of mixed crystal structure. Nevertheless, Co3O4 slightly appeared with low peak intensity which came from the oxidation reaction of as-prepared catalyst during calcinations. XRD showed that PVA did not effect to crystal structure of synthesized catalyst. Higher PVA content added in the precursor cause the reduction of crystal growth of catalyst in calcinations step. In contrast, morphology of catalyst is directly related with PVA content such that the spongy and sheet-like structure were formed with increasing PVA content which prevented the agglomeration of particles. The results showed that PVA content play an important role in morphology of perovskite-type mixed oxide catalysts but did not affected to their crystal structures.

X-ray absorption and XPS study of titanium mixed oxides synthesized by the sol–gel method

2001 ◽  
Vol 114-116 ◽  
pp. 307-311 ◽  
Author(s):  
José E. Gonçalves ◽  
Sandra C. Castro ◽  
Aline Y. Ramos ◽  
Maria C.M. Alves ◽  
Yoshitaka Gushikem
Keyword(s):  
Mixed Oxides ◽  
Sol Gel ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Xps Study ◽  
X Ray Absorption

Synthesis by sol–gel process, characterization and catalytic activity of vanadia–silica mixed oxides

2005 ◽  
Vol 351 (46-48) ◽  
pp. 3624-3629 ◽  
Author(s):  
Mariza Alves Figueiredo ◽  
André Luiz de Faria ◽  
Marilda das Dores Assis ◽  
Herenilton Paulino Oliveira
Keyword(s):  
Catalytic Activity ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Process Characterization ◽  
Sol Gel Process

Effect of solvo-thermal treatment temperature on the properties of sol–gel ZrO2–TiO2 mixed oxides as HDS catalyst supports

2006 ◽  
Vol 116 (4) ◽  
pp. 498-504 ◽  
Author(s):  
María C. Barrera ◽  
José Escobar ◽  
José A. de los Reyes ◽  
María A. Cortés ◽  
Margarita Viniegra ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Treatment Temperature ◽  
Catalyst Supports ◽  
Thermal Treatment Temperature

scholarly journals A thermodynamic investigation of the redox properties of ceria–titania mixed oxides

2008 ◽  
Vol 335 (2) ◽  
pp. 153-158 ◽  
Author(s):  
Gong Zhou ◽  
Jonathan Hanson ◽  
Raymond J. Gorte
Keyword(s):  
Mixed Oxides ◽  
Redox Properties ◽  
Thermodynamic Investigation

Catalysts for Wet Air Oxidation Based on Ce-Zr-Pr-O Mixed Oxides Prepared by Soft Chemistry

2006 ◽  
Vol 45 ◽  
pp. 2089-2095
Author(s):  
Jana Mikulová ◽  
Sylvie Rossignol ◽  
Jacques Barbier Jr. ◽  
Charles Kappenstein ◽  
Daniel Duprez
Keyword(s):  
Aqueous Solution ◽  
Mixed Oxides ◽  
Platinum Catalyst ◽  
Sol Gel ◽  
Ruthenium Catalysts ◽  
Catalytic Wet Air Oxidation ◽  
Air Oxidation ◽  
Wet Air Oxidation ◽  
Soft Chemistry ◽  
Pure Ceria

Sol-gel Zr0.1Ce0.9O2 and Zr0.1(Ce0.75Pr0.25)O2 mixed oxides and coprecipitated pure ceria CeO2 displaying the fluorine type structure have been used as platinum or ruthenium catalysts’ supports for catalytic wet air oxidation (CWAO) of aqueous solution of acetic acid (78 mmol.L-1). These catalysts were prepared by conventional impregnation (5 wt-%) from platinum and ruthenium precursor salts or by exchange (~2 wt-%) in the case of ruthenium. A screening of catalysts in CWAO at 200°C under 2 MPa was performed and reveals that the best platinum catalyst is supported on pure ceria displaying large surface. For ruthenium catalysts, the highest conversion after 3 hours of reaction has been reached by the Ru/Zr-Ce-O system.

scholarly journals Insights into the relationship between the catalytic oxidation performances of Ce-Pr mixed oxides and their semiconductive and redox properties

2019 ◽  
Vol 578 ◽  
pp. 30-39 ◽  
Author(s):  
Ionel Popescu ◽  
Juan Carlos Martínez-Munuera ◽  
Avelina García-García ◽  
Ioan-Cezar Marcu
Keyword(s):  
Catalytic Oxidation ◽  
Mixed Oxides ◽  
Redox Properties ◽  
The Relationship

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

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1771 ◽  
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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