Synthesis of Crystallized Mesoporous Tantalum Oxide and Its Photocatalytic Activity for Overall Water Splitting under Ultraviolet Light Irradiation

Noda, Yu; Lee, Byongjin; Domen, Kazunari; Kondo, Junko N.

doi:10.1021/cm703202n

Cited by 163 publications

(114 citation statements)

References 46 publications

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“…Thus, crystalline mesoporous metal oxides are regarded as a new family of materials, which possesses unique catalytic properties. As one of the examples enhancement of the photocatalytic activity for overall water decomposition over mesoporous Ta 2 O 5 upon crystallization has been reported [8,9]. We recently reported that both cis-and trans-1,2-cyclohexanediols were selectively produced in the oxidation of cyclohexene over amorphous mesoporous Nb 2 O 5 using H 2 O 2 as an oxidant, and details in the reaction were directly observed by infrared (IR) spectroscopy [10].…”

Section: Introductionmentioning

confidence: 97%

Changes in Surface Property and Catalysis of Mesoporous Nb2O5 from Amorphous to Crystalline Pore Walls

et al. 2010

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The amorphous inorganic phase of an ordered amorphous mesoporous Nb 2 O 5 with two dimensional hexagonal (2D-hex) structure was crystallized with maintaining the original well arranged porous structure. The difference in surface property between amorphous and crystalline Nb 2 O 5 with similar ordered mesoporous structure was compared. It was found from water adsorptiondesorption isotherms and observation by infrared (IR) spectroscopy that the amorphous sample was hydrophilic and that the surface OH groups were acidic. On the other hand, the OH groups on crystalline mesoporous Nb 2 O 5 were non-acidic and inside the pores was less hydrophilic. The surface property was also compared by a catalytic reaction, oxidation of cyclohexe by an aqueous solution of H 2 O 2 . The high (95%) selectivity for 1,2-epoxycyclohexane was obtained at 40°C for 2 h in methanol solvent over crystalline mesoporous Nb 2 O 5 at 12% conversion, while amorphous mesoporous Nb 2 O 5 showed high (68%) selectivity for 1,2-cyclohexanediol in acetonitrile solvent at 60°C for 2 h at 22% conversion. The differences in selectivity and the optimal solvent between amorphous and crystalline samples were interpreted in terms of the acidic feature of surface OH groups and hydrophilicity. While similar selectivity was observed over non-porous crystalline Nb 2 O 5 , much higher conversion over crystalline mesoporous Nb 2 O 5 was attained at the same surface area. Thus, an advantage of mesoporous structure is attributed to the higher contact time of molecules inside the pores to the catalyst surface than those outside the particles.

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Section: Introductionmentioning

confidence: 97%

Changes in Surface Property and Catalysis of Mesoporous Nb2O5 from Amorphous to Crystalline Pore Walls

et al. 2010

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“…As important solid acids, transitionmetal oxides are currently attracting considerable attention due to their unique properties and broad range of potential applications. During the last decades, monometallic oxides such as MgO [9][10][11], SnO 2 [12][13][14], WO 3 [12,14], ZrO 2 [12,14,15], TiO 2 [12,14,16], Al 2 O 3 [17], Nb 2 O 5 [12,14,18], Ta 2 O 5 [12,14,19], and bimetallic oxides such as Nb-Ta oxides [12,14,20,21], Mg-Ta oxides [21,22], Nb-W oxides [23], Sn/W oxides [24], Zr-W oxides [25,26], and WO 3 -TiO 2 [27] have all been studied. The transition-metal centers in the inorganic frameworks of porous structures also possess variable oxidation states and empty d-orbitals, which allow electron transfer to occur between the reactants and active sites during the catalytic process [28].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of highly active Sn/W mixed transition-metal oxides as solid acid catalysts

Yang

Lengyuan

et al. 2011

Transition Met Chem

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Catalytically active Sn/W mixed transition-metal oxides were prepared by calcination of the corresponding Sn/W hydroxide precursors at different temperatures. The obtained mixed oxides were characterized by physicochemical and spectroscopic methods. With variation of the molar ratios of Sn/W, the prepared Sn/W mixed oxide catalysts had different reaction activities. Thus, the Sn/W-2-800 oxide acted as an effective heterogeneous catalyst for the Baeyer-Villiger oxidation of ketones and the Friedel-Crafts reaction. Many ketones, as well as benzyl alcohol and acetic anhydride, were transformed into the corresponding products with high conversion and selectivity. The catalysts can be easily separated from the reaction mixtures and can be reused for at least five cycles without significant loss of activity.

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“…These materials have been used in the isomerization of alkanes and other petrochemical processes such as alkylation of aromatics and hydrocarbon cracking [105]. Monometallic oxides such as MgO [106], SnO2 [107], WO3 [108], ZrO2 [109], TiO2 [110], Al2O3 [111], Nb2O5 [112], Ta2O5 [113], and bimetallic oxides such as Nb-Ta oxides [114,115], Mg-Ta oxides [116], Nb-W oxides [117], Sn-W oxides [118], Zr-W oxides [119], and WO3-TiO2 [120,121] have been extensively explored. The transition-metal centers in the inorganic frameworks of porous structures also possess variable oxidation states and empty d-orbitals, which allow electron transfer to occur between the reactants and active sites during the catalytic process [122].…”

Section: Mo-sno2 Metal Oxide Nanocomposite Catalystsmentioning

confidence: 99%

Sn-based catalysts for Baeyer-Villiger oxidations by using hydrogen peroxide as oxidant

Cui

Shi

2016

Sci. China Mater.

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Baeyer-Villiger (BV) oxidation is one of the most important transformation reactions in synthetic organic chemistry. Catalytic versions of the BV oxidation are particularly attractive in practical applications, because the catalytic transformation substantially simplifies reaction process while minimizing reactant consumption as well as waste production. Further benefits are expected from replacing peracids, the traditionally used oxidant, by low cost and environmentally friendly hydrogen peroxide (H2O2). This review will first introduce very briefly the features of BV oxidation reactions, and the corresponding oxidants traditionally used. Afterwards, the emphasis will be placed on the specific Sn-based catalysts, their performance comparison for the BV oxidation reaction by using H2O2 as oxidant, and the catalytic mechanisms of most Sn-based catalysts reported so far, including homogeneous Sn-based catalysts (such as Sn-based fluorous biphase system catalysts), heterogeneous Sn-based catalysts (such as Sn-based zeolite catalysts, Sn-based mesoporous composites, Sn-incorporated clay catalysts, Sn-based metal oxide composites and polymer supported Sn catalysts). Finally, the Sn-based catalysts for BV oxidation are outlooked for their potentials and perspectives in enhancing the performance and then accelerating the practical applications of BV oxidations by using H2O2. The developing direction of the Sn-based catalytic BV reaction is also illustrated.

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Synthesis of Crystallized Mesoporous Tantalum Oxide and Its Photocatalytic Activity for Overall Water Splitting under Ultraviolet Light Irradiation

Cited by 163 publications

References 46 publications

Changes in Surface Property and Catalysis of Mesoporous Nb2O5 from Amorphous to Crystalline Pore Walls

Changes in Surface Property and Catalysis of Mesoporous Nb2O5 from Amorphous to Crystalline Pore Walls

Fabrication of highly active Sn/W mixed transition-metal oxides as solid acid catalysts

Sn-based catalysts for Baeyer-Villiger oxidations by using hydrogen peroxide as oxidant

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