Visible-light-responsive photocatalytic reaction on tetrahedrally-coordinated chromium oxide moieties loaded on ZSM-5 zeolites and HMS mesoporous silica: partial oxidation of propane

Yamashita, Hiromi; Ohshiro, Satoshi; Kida, Kenji; Yoshizawa, Keiko; Anpo, Masakazu

doi:10.1163/156856703322601870

Cited by 28 publications

(18 citation statements)

References 17 publications

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“…Meanwhile, highly dispersed Cr(VI)-oxide (chromate) species have also received much attention. [18][19][20][21][22] The chromate species have a ligand-to-metal charge transfer (LMCT) absorption at >400 nm and act as a visible light-driven photocatalyst: Cr-containing mesoporous silica molecular sieve (Cr∝HMS) prepared by a surfactant-templating method, 18,19 Cr-impregnated HMS (Cr/HMS) and ZSM-5 (Cr/ZSM-5) 20 promote NO decomposition and propane oxidation by visible light with O 2 in a gas/solid system. Yoshida et al have reported that the Cr-Si binary oxide (Cr-SiO 2 ) prepared by a conventional sol-gel method promotes selective epoxidation of propene with O 2 by visible light.…”

Section: Introductionmentioning

confidence: 99%

Visible Light-Induced Partial Oxidation of Olefins on Cr-Containing Silica with Molecular Oxygen

2006

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Photocatalytic oxidation of olefins on Cr-containing silica with molecular oxygen by visible light irradiation (lambda > 400 nm) has been investigated. Cr-SiO(2) catalyst prepared by a conventional sol-gel method, containing highly dispersed chromate species, catalyzes efficient olefin oxidation with very high selectivity for partially oxidized products (>90%), whereas semiconductor TiO(2) promotes complete decomposition (CO(2) production). The Cr-SiO(2) catalyst shows much higher activity than Cr/SiO(2) prepared by an impregnation method or Cr proportional variant MCM-41 prepared by a templating method. ESR analysis reveals that photoirradiation of the chromate species with a tetrahedral coordination (T(d)(6+)) on Cr/SiO(2) and Cr proportional variant MCM-41 catalysts leads to the formation of excited state T(d)(5+) species (T(d)(5+*)), while irradiation to T(d)(6+) on Cr-SiO(2) produces T(d)(4+*) species. This can be explained by a homogeneous T(d)(6+) arrangement with Si species on the Cr-SiO(2) catalyst. On the strongly reduced T(d)(4+*), olefins are strongly attracted by an electron and/or proton donation, resulting in high oxidation activity. The Cr-SiO(2) catalyst is applicable to partial oxidation of various aliphatic and aromatic olefins with very high selectivity, and does not promote undesirable dimerization. The obtained findings suggest a potential use of Cr-SiO(2) as an efficient and recyclable heterogeneous photocatalyst for partial oxidation of olefins.

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Section: Introductionmentioning

confidence: 99%

Visible Light-Induced Partial Oxidation of Olefins on Cr-Containing Silica with Molecular Oxygen

2006

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“…The XANES spectra of the Ti containing compounds at the Ti K-edge and that of the Cr containing compounds at the Cr K-edge show several well-defined preedge peaks. These relative intensities of the preedge peaks are related to the local structures surrounding the Ti atom and Cr atom and provide useful information on the coordination number surrounding the Ti atom and Cr atom [1,10,11,20,21]. As shown in Fig.…”

Section: Characterization and Measurement Of Contactmentioning

confidence: 99%

“…The polymerization of ethylene on the Cr-containing mesoporous silica (CMS) thin film was carried out by UV-light irradiation of sample in the presence of ethylene gas. Figure 7 shows the IR spectra of the samples observed before and after UV-light irradiation for ethylene polymerization [10,11,24]. The observation of the two strong bands at 2,854 cm -1 and 2,916 cm -1 assigned to symmetric and antisymmetric stretching modes of CH 2 groups and a weak peak at 2,955 cm -1 assigned to stretching vibration of terminal CH 3 group with the sample after UV-light irradiation indicate the formation the formation of polyethylene on the surface of the Cr-containing mesoporous silica (CMS) thin film.…”

Section: Effect Of Ethylene Polymerization Over Cms Thin Filmsmentioning

confidence: 99%

“…For example Ti-containing zeolite has an isolated tetrahedrally coordinated titanium oxide moieties which can show the efficient and selective reactions under UV-light irradiation for various reactions such as the reduction of CO 2 with H 2 O [3][4][5][6], NO decomposition into N 2 and O 2 [7,8], and the selective photoepoxidation of alkene with O 2 [9]. On the other hands, Cr-containing mesoporous silica also has an isolated tetrahedrally coordinated chromium oxide moieties which can show photocatalytic reactivity for highly selective oxidation of alkane not only under UV-light irradiation but also visible-light irradiation [10,11].…”

Section: Introductionmentioning

confidence: 99%

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Photo-induced Surface Property on Transparent Mesoporous Silica Thin Films Containing Single-site Photocatalyst

et al. 2008

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The transparent Ti-containing or Cr-containing mesoporous silica thin films can be prepared on quartz plate using a spin-coating sol-gel method. The spectroscopic characterization has revealed that these thin films contain isolated and tetrahedrally coordinated titanium oxide moieties and chromium oxide moieties in their frameworks, respectively. These mesoporous silica thin films containing metal oxide moieties have demonstrated a strong hydrophilic surface property even before UV-light irradiation and the appearance of the super-hydrophilic property after UV-light irradiation. Especially, the Cr-containing mesoporous silica (CMS) thin film showed the super-hydrophilic property even under visible light irradiation. In the presence of ethylene gas, the polyethylene was successfully formed on the surface of the CMS thin film under UV-light irradiation. After the formation of polyethylene the surface property of the CMS was converted into hydrophobic while keeping its transparency. The isolated and tetrahedrally coordinated titanium oxide moieties and chromium oxide moieties are responsible for these photo-induced surface reactions.

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“…Several photoactive heteroatoms have been added to zeolite frameworks for different photocatalytic applications. Y, ZSM, and beta zeolites have been used as hosts, while heteroatoms such as titanium, , molybdenum, chromium, and vanadium have been successfully dispersed and showed promising results in decontamination and/or selective green chemistry processes. As a matter of fact, processes involving the transformation of methane into larger hydrocarbons and/or methanol with zeolites as (photo)catalysts have also been proposed.…”

Section: Introductionmentioning

confidence: 99%

Controlled Photocatalytic Oxidation of Methane to Methanol through Surface Modification of Beta Zeolites

et al. 2017

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The selective oxidation of methane to methanol is achieved by means of a photocatalytic process. For this purpose, designed Bi- and V-containing beta zeolites prepared by incipient wetness impregnation have been used under different test conditions. While the zeolite proves to be photoactive under UVC irradiation toward the total oxidation process, the formation of V2O5 on the surface is an effective alternative for modifying the acid–base surface properties, thus significantly decreasing the undesired CO2 formation. At the same time the zeolite framework serves as a scaffold for increasing the surface area and distribution of the metal oxide. Additionally, the addition of low Bi amount favors the formation of a BiVO4/V2O5 heterojunction, which acts as a visible light photocatalyst while at the same leading to total selectivity to methanol at the expense of ethylene formation.

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Visible-light-responsive photocatalytic reaction on tetrahedrally-coordinated chromium oxide moieties loaded on ZSM-5 zeolites and HMS mesoporous silica: partial oxidation of propane

Cited by 28 publications

References 17 publications

Visible Light-Induced Partial Oxidation of Olefins on Cr-Containing Silica with Molecular Oxygen

Visible Light-Induced Partial Oxidation of Olefins on Cr-Containing Silica with Molecular Oxygen

Photo-induced Surface Property on Transparent Mesoporous Silica Thin Films Containing Single-site Photocatalyst

Controlled Photocatalytic Oxidation of Methane to Methanol through Surface Modification of Beta Zeolites

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