Highly dispersed Ce(iii) species on silica and alumina as new photocatalysts for non-oxidative direct methane coupling

Yuliati, Leny; Hamajima, Toyokazu; Hattori, Tadashi; Yoshida, Hisao

doi:10.1039/b507698f

Cited by 51 publications

(23 citation statements)

References 31 publications

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“…Such paramagnetic signals are not seen with increasing cerium loading on Al-MCM-41 indicating that the chemical environment of cerium at low loadings is different from that of cerium at higher loadings. Thus the formation of Ce 3+ species at lower cerium loading is in agreement with the earlier report [16].…”

Section: Xpssupporting

confidence: 93%

“…2. The ceria shows an absorption band edge around 420 nm and a band at 370 nm that may be due to the charge transfer from O (valence band) to Ce (conduction band) [16]. The Al-MCM-41 shows an absorption band below 210 nm due to the presence of Al in tetrahedral coordination [21].…”

Section: Uv-vis Drsmentioning

confidence: 99%

“…Cerium oxide has been employed as a photocatalyst in some of the reactions like water splitting, toluene oxidation and waste water treatment [12][13][14][15]. Yuliati et al reported that cerium oxide in Ce 4+ state is not able to show the photocatalytic activity and silica based ceria catalysts showed photocatalytic activity [16]. In rare earth ions (Ce 3+ , Pr +3 etc.)…”

Section: Introductionmentioning

confidence: 99%

“…In rare earth ions (Ce 3+ , Pr +3 etc.) photoexcitation is generally caused due to f-d orbital transitions [16]. In the present investigation an attempt has been made to study the photoactivity of highly dispersed cerium on a mesoporous Al-MCM-41 support wherein Ce shows variable oxidation states on photoexcitation.…”

Section: Introductionmentioning

confidence: 99%

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Ce Dispersed Al-MCM-41: A Photocombinate for Phenol Degradation Activity

2008

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Al-MCM-41 supported ceria samples of various cerium content (0.2, 0.3, 0.5, 0.8 and 3.0 wt.%) were prepared by impregnation and are characterized by BET, XRD, UV-VIS DRS, XPS and ESR techniques. At lower cerium contents the DRS clearly shows a blue shift of 50 nm in the absorbtion edge of CeO 2 indicating the size quantization and high dispersion of cerium particles. The XPS analyses of Ce-Al-MCM-41 samples revealed the interaction of cerium with Al-MCM-41 in Ce 3+ state and at higher loadings in Ce 3+/4+ states. ESR studies also further substantiated this observation. These catalysts when subjected to photo degradation activity of phenol, 0.3 wt.% Ce-Al-MCM-41 is showing maximum degradation among all the catalysts tested.The present study highlights that cerium at lower loadings is in +3 oxidation state and is dispersed highly showing good photocatalytic activity in comparison with pure ceria.

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Section: Xpssupporting

confidence: 93%

Section: Uv-vis Drsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ce Dispersed Al-MCM-41: A Photocombinate for Phenol Degradation Activity

2008

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“…The recorded images of CeO 2 (0.4)/GO catalyst exposed dominant (1 0 0) facets with interplanar spacing of about 0.27 nm compared to ceria nanocrystalline morphology. This result is clearly evidenced the {1 0 0} facet was found to be dominating facet along with (1 1 1), (1 1 0) and (3 1 1) facets ,. SAED pattern of flower‐like CeO 2 (0.4)/GO was clearly shows the dark spot for {1 0 0} facet, which is further evident the presence of exposed {1 0 0} facet as shown in Figure c (insert figure).…”

Section: Resultsmentioning

confidence: 79%

Selective Oxidation of Cyclohexane Using Graphene Oxide‐Supported Ceria Nanocomposites with Exposed Active {1 0 0} Facets

et al. 2017

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The present study is focused on the synthesis and characterization of ceria loaded graphene oxide (GO) and investigates their catalytic activity on vapor phase selective oxidation of cyclohexane. In this regards, we have synthesized various loading of CeO 2 on GO with two different morphology includes nanocrystals and flower-like, which designated as CeO 2 (x)/GO (where x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0 wt.%). The physicochemical properties of the materials were extensively studied with help of XRD, N 2 adsorption desorption (BET), DRUV-Vis, HRSEM, HRTEM, H 2 -TPR and XPS techniques. The crystalline nature of materials were analyzed by XRD, pure ceria shows high crystalline size about 15. 3 nm compared to others. Surface area of synthesized materials has been obtained with help of N 2 adsorption desorption analysis, pure ceria and graphene oxide shows surface area about 93 and 574 m 2 /g, respectively. XPS and DRUV-Vis spectra were confirms the presence of enormous Ce 3 + ions in the lattice. The presence of nanocrystals and flower-like morphology of CeO 2 (x)/GO were confirmed by HRSEM images. HRTEM images were clearly illustrated that the presence of dominant active {1 0 0} facets in flower-like CeO 2 /GO than that of nanocrystalline morphology. The catalytic activity of materials has been evaluated on selective oxidation of cyclohexane using air as a green oxidant.The key reaction parameters were varied to study the stability, activity and selectivity of the catalysts. The activity of the catalysts is correlated with their physico-chemical properties, and these results concluded that suitable amount of ceria and it's flower-like morphology on GO is essential for selective oxidation of cyclohexane at low temperature (180 8C) compared to nanocrystalline morphology. Hence, flower-like CeO 2 (0.4)/GO is a most suitable catalyst for high conversion (90%) of cyclohexane into cyclohexanone with 74% selectivity due to occurrence of enormous {1 0 0} facet and Ce 3 + .

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Nanoparticles for Cell Engineering – A Radical Concept

Rzigalinski

Danelisen

Strawn

et al. 2003

Nanotechnologies for the Life Sciences

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The sections in this article are Introduction and Overview Free Radicals and Oxidative Stress Sources of Intracellular Free Radicals Oxidative Stress Oxidative Stress and Disease A Nanotechnological Approach to Oxidative Stress Rare Earth Oxide Nanoparticles – Cerium Biological Effects of Cerium Biological Effects of Cerium Oxide Nanoparticles Other Oxide Nanoparticles Fullerene Derivatives and Carbon Nanotubes Nano‐Pharmacology Absorption Agglomeration Dose Distribution, Metabolism, and Excretion Nanoparticle Antioxidants and Treatment of Disease Toxicology Summary

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Highly dispersed Ce(iii) species on silica and alumina as new photocatalysts for non-oxidative direct methane coupling

Abstract: Highly dispersed cerium oxide species on silica and alumina, which mainly exist as Ce(III) species, promote non-oxidative direct methane coupling photocatalytically around room temperature, while Ce(IV) species as CeO2 particles do not behave as a catalyst for this reaction.

Cited by 51 publications

References 31 publications

Ce Dispersed Al-MCM-41: A Photocombinate for Phenol Degradation Activity

Ce Dispersed Al-MCM-41: A Photocombinate for Phenol Degradation Activity

Selective Oxidation of Cyclohexane Using Graphene Oxide‐Supported Ceria Nanocomposites with Exposed Active {1 0 0} Facets

Nanoparticles for Cell Engineering – A Radical Concept

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