Preparation and characterization of highly dispersed silica-supported ceria

Bensalem, Abdelhamid; Bozon‐Verduraz, François; Delamar, Michel; Bugli, G.

doi:10.1016/0926-860x(95)85012-0

Cited by 280 publications

(171 citation statements)

References 22 publications

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“…The peak at 210 nm corresponds to dispersed Ce 3+ species [2] and the one at 260 nm is due to the 4f-5d interconfiguration transitions of Ce 3+ species [24]. The band at 310 nm has been assigned to CeO 2 [23][24][25] and increases with cerium loading. Therefore, a mixture of cerium species in 3+ and 4+ states coexists in Ce-HMOR and in Ce-Pd-HMOR catalysts.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

Lean NOx reduction with dodecane over cerium and palladium loaded mordenite

Córdoba

Flytzani‐Stephanopoulos

Correa

2001

Applied Catalysis B: Environmental

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The selective catalytic reduction (SCR) of NO x by dodecane in excess oxygen-containing gas mixtures was studied on Ce and/or Pd-loaded HMOR. Under dry conditions the best fresh bimetallic catalyst, 6.2 wt.% Ce-0.08 wt.% Pd-HMOR, displayed a maximum of about 70% NO x conversion to N 2 at 350 • C and GHSV = 30,000 h −1 , while either Ce-HMOR or Pd-HMOR exhibited low activity for the SCR reaction. The presence of both Ce and Pd in the zeolite was crucial for high deNO x activity. The dodecane concentration is very important for the reaction. The catalyst is not active in the absence of the reducing agent and inhibition of NO x reduction is observed at dodecane concentrations higher than 440-500 ppm. The presence of 40 ppm SO 2 in the gas feed suppresses the reaction. However, the coexistence of 15% H 2 O and 40 ppm SO 2 has no appreciable effect on the catalyst activity. Enhanced activity and a broader temperature window was observed in the NO 2 + dodecane + O 2 reaction in the presence of 15% H 2 O and 100 ppm SO 2 . In this reaction mixture, the catalyst was capable of retaining a stable NO 2 conversion to N 2 for a period of ten days. Characterization by XPS and UV-VIS-diffuse reflectance spectra (UV-VIS-DRS) of selected fresh and aged catalyst samples indicates that Pd exists mainly as Pd 2+ cations in Ce-Pd-HMOR. Cerium is mostly present as CeO 2 on the surface of the zeolite particles. However, part of the cerium in 6Ce-Pd-HMOR, exists as stable Ce 3+ species.

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Section: Catalyst Characterizationmentioning

confidence: 99%

Lean NOx reduction with dodecane over cerium and palladium loaded mordenite

Córdoba

Flytzani‐Stephanopoulos

Correa

2001

Applied Catalysis B: Environmental

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“…The XPS spectrum of the calcined Fe 3 O 4 @SiO 2 shows two O 1s components at binding energy (BE) 533.0 and 530.3 eV, attributed respectively to bulk SiO 2 and to surface hydroxyl groups, although, the latter is often observed in several oxides. The XPS spectrum for Fe 3 O 4 @SiO 2 -CeO 2 showed an increase in the O 1s component at BE 530.7 eV, a feature attributed to the occurrence of CeO 2 [24]. There is an increase of 2.1 eV, compared to pure CeO 2 as a consequence of the decrease in the basicity of small CeO 2 particles.…”

Section: Post-coating Process: Magnetic Supports Containing Ceria Timentioning

confidence: 92%

Separation technology meets green chemistry: development of magnetically recoverable catalyst supports containing silica, ceria, and titania

Vono

Damasceno

Matos

et al. 2017

Pure and Applied Chemistry

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Magnetic separation can be considered a green technology because it is fast, efficient, consumes low energy, and minimizes the use of solvents and the generation of waste. It has been successfully used in laboratory scale to facilitate supported catalysts' handling, separation, recovery, and recycling. Only few materials are intrisically magnetic, hence the application of magnetic materials as catalyst supports has broaden the use of magnetic separation. Iron oxides, silica-coated iron oxides, and carbon-coated-cobalt are among the most studied catalyst supports; however, other metal oxide coatings, such as ceria and titania, are also very interesting for application in catalysis. Here we report the preparation of magnetically recoverable magnetic supports containing silica, ceria, and titania. We found that the silica shell protects the iron oxide core and allows the crystalization of ceria and titania at high temperature without compromising the magnetic properties of the catalyst supports.

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“…The two maximum adsorption peaks produced by the unsupported ceria can be credited to the specular reflectance which affects the shape of the interband transition, although not modifying the absorption peak position which appears at ca. 400 nm [25]. In the case of the Ce-SBA-15 and Ce-Im-SBA-15 samples, the adsorption peak shifts to 300 nm and 280 nm, respectively.…”

Section: Effect Of Ln/si Ratiomentioning

confidence: 98%

Direct synthesis of lanthanide-containing SBA-15 under weak acidic conditions and its catalytic study

Hao

et al. 2008

Microporous and Mesoporous Materials

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Lanthanide (Ln including La, Ce and Nd) containing SBA-15 molecular sieves with molar ratio Ln/Si = 0.01-0.2 were prepared via direct synthesis under weak acidic conditions (pH 1.5-3.0). Characterizations of these samples were done by powder X-ray diffraction, N 2 adsorption, inductively coupled plasma atomic emission spectrometry (ICP-AES), FT-IR spectroscopy, and diffuse reflectance ultraviolet spectroscopy. All the samples show a highly ordered two-dimensional hexagonal mesostructure. N 2 adsorption testifies that all the Ln-containing SBA-15 materials have the type IV isotherms with type H 1 hysteresis loop as well as high specific surface area (798-925 m 2 /g) and narrow pore size distribution. The diffuse reflectance UV-vis, ICP-AES, and the wide-angle XRD spectra show that most of the lanthanide ions are better dispersed in the calcined materials. The Ln-SBA-15 supported Pd catalysts show high catalytic activity in the oxidation of benzene. The results reveal that Ln-SBA-15 materials can be used as potential supports for the catalytic oxidation of VOCs.

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Preparation and characterization of highly dispersed silica-supported ceria

Cited by 280 publications

References 22 publications

Lean NOx reduction with dodecane over cerium and palladium loaded mordenite

Lean NOx reduction with dodecane over cerium and palladium loaded mordenite

Separation technology meets green chemistry: development of magnetically recoverable catalyst supports containing silica, ceria, and titania

Direct synthesis of lanthanide-containing SBA-15 under weak acidic conditions and its catalytic study

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