Direct organic functionalization of Ti–MCM-41: Synthesis condition, organic content, and catalytic activity

Igarashi, Naoko; Kidani, Satoshi; Ahemaito, Rizwan; Hashimoto, Kazuhito; Tatsumi, Takashi

doi:10.1016/j.micromeso.2005.01.022

Cited by 44 publications

(32 citation statements)

References 26 publications

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“…Interestingly, the unit cell size (a 0 ), in the 43-47 Å range, was not significantly altered in the modified materials with respect to the parent MCM-41 (Table 1). These results were in good agreement with those reported by Igarashi and Tatsumi et al [32,33] in the preparation of similar organically modified Ti-MCM-41 materials.…”

Section: Resultssupporting

confidence: 93%

Preparation of Mesoporous Organically Modified Titanium Materials and their Activity in the Oxidation of Cyclohexene

et al. 2008

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Mesoporous organically modified Ti-MCM-41 materials were synthesised employing different Ti precursors. Materials were found to possess improved properties in terms of stability, hydrophobicity and activity compared to the parent Ti-MCM-41, preserving their mesoporous structural order. The organically modified mesoporous materials were tested in the oxidation of cyclohexene using conventional heating and microwaves. The microwave assisted protocol was found to enhance reaction rates and selectivities to the epoxide, reducing the times of reaction from 24 to less than 1 h at comparable activities (60-80% conversion).

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Section: Resultssupporting

confidence: 93%

Preparation of Mesoporous Organically Modified Titanium Materials and their Activity in the Oxidation of Cyclohexene

et al. 2008

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“…The presence of Lewis acid sites were confirmed on both amorphous and crystalline mesoporous Nb 2 O 5 catalysts by low temperature CO adsorption (CO bands at 2190 and 2164 cm -1 for 1, 2-Epoxyhexane is industrially produced by the oxidation of 1-hexene over a titanosilicate zeolite, TS-1 [14], using H 2 O 2 in an eco-friendly process. The oxidation of alkenes is often used to evaluate the catalytic performance of Ti-containing silica-based catalysts [15][16][17] as well as Ta-modified mesoporous silica [18]. Among various alkenes, large-sized alkenes are not efficiently oxidized by titanosilicate zeolites due to the limitation in pore size.…”

Section: Ir Characterizationmentioning

confidence: 99%

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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“…As discussed earlier, the relatively low oxidiation ability and hydrothermal stability can be attributed to the difference in the titanium coordination environment (amorphous nature of the mesoporous wall, hydrophilic surfaces, etc.). Now a days, researchers very much believe that catalytic activity of porous solids highly depends on the hydrophobicity of the catalyst, typically for aqueous mediated catalytic reactions (for example, in presence of H 2 O 2 oxidant) [30,31]. Hence, in order to achieve higher hydrophobicity in the mesoporous materials, in addition to postsynthesis silylation of mesoporous silicas, several one-step synthesis procedures were proposed using different functional groups along with titanium species.…”

Section: Titanium-containing Mesoporous Silicas and Organosilicasmentioning

confidence: 99%

Periodic Mesoporous Silicas and Organosilicas: An Overview Towards Catalysis

et al. 2008

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Micelle-templated mesoporous and organicinorganic hybrid mesoporous materials are important in many fields of material research, especially for hosting catalysts in confined space. Among this class, the recent discovery of periodic mesoporous organosilicas (PMOs) represent an exciting new group of organic-inorganic nanocomposites targeted for a broad range of applications ranging from catalysis to microelectronics. Compared to the earlier generation of organic-inorganic hybrid mesoporous samples, obtained by the cocondensation reaction or by the grafting reaction, PMOs represent the right combination of organic and inorganic groups in the frame wall positions. This article reviews the current state of art in organic-inorganic hybrid mesoporous material research with special emphasis over periodic mesoporous organosilica materials having various redox centers (Ti, V, Cr) suitable for oxidation reactions as well as acidic sites (Al, -SO 3 H) for the organic transformation of bulky molecules.

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Direct organic functionalization of Ti–MCM-41: Synthesis condition, organic content, and catalytic activity

Cited by 44 publications

References 26 publications

Preparation of Mesoporous Organically Modified Titanium Materials and their Activity in the Oxidation of Cyclohexene

Preparation of Mesoporous Organically Modified Titanium Materials and their Activity in the Oxidation of Cyclohexene

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

Periodic Mesoporous Silicas and Organosilicas: An Overview Towards Catalysis

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