Toshiyuki Yokoi

Uniform-sized silica nanospheres with a well-ordered arrangement were successfully synthesized by a novel and simple method; hydrolysis and condensation reactions of tetraethyl orthosilicate were conducted in the presence of basic amino acids.

Amino-functionalized mesoporous MCM-41 materials were synthesized directly by co-condensation of 3-aminopropyltrimethoxysilane (N silane), [1-(2-aminoethyl)-3-aminopropyl]trimethoxysilane (NN silane) or 1-[3-(trimethoxysilyl)propyl]diethylenetriamine (NNN silane) with tetraethyl orthosilicate. The maximum proportions of N, NN and NNN silanes in the Si sources for obtaining the hexagonally structured functionalized silica were 0.5, 0.4 and 0.4, respectively. The 29Si MAS NMR measurements of the m

The effects of the organic structure-directing agents (OSDAs) and Na cations for the synthesis of ZSM-5 on the location of Al atom in the framework as well as the acidic and catalytic properties were investigated. To achieve these purposes, ZSM-5 zeolites were synthesized by using four kinds of OSDAs including tetrapropylammonium hydroxide cations, dipropylamine, cyclohexylamine, and hexamethylenimine with or without Na cations. In situ FT-IR spectroscopy using CO as probe molecule was applied t

A liquid-phase method for preparing uniform-sized silica nanospheres (SNSs) 12 nm in size and their three-dimensionally ordered arrangement upon solvent evaporation have recently been pioneered by us. The SNSs are formed in the emulsion system containing Si(OEt)4 (TEOS), water, and basic amino acids under weakly basic conditions (pH 9−10). Here, we report the formation mechanism of the SNSs; the reasons for the uniform size and the ordered arrangement are described in detail. The formation proce

Mesoporous silica containing a large amount of aminopropyl groups has been successfully synthesized via the anionic templating route. The electrostatic interaction between the positively charged amino groups in 3-aminopropyltriethoxysilane and the negatively charged sulfate head groups in sodium dodecyl sulfate is a driving force for the self-assembly of silica−micelle composite.

The RTH-type zeolite (see picture) has an attractive pore structure, but its compositional variation is limited. Now, metallosilicates with the RTH-topology can be synthesized by two routes, one of which does not use structure-directing agents. Thus prepared Al-containing RTH-type zeolites exhibited a remarkable catalytic performance for the methanol-to-olefins reaction, producing propene with high selectivity. Detailed facts of importance to specialist readers are published as ”Supporting Infor

A “S−N+∼I− pathway” (S−: anionic surfactant, N+: cationic amino group and I: inorganic species) for the synthesis of mesoporous silica has been developed by using 3-aminopropyltriethoxysilane (APS) as a co-structure directing agent (CSDA), which can interact with the anionic head group in the surfactant (SDA). Thus synthesized mesoporous silica has been designated as AMS (Anionic-surfactant-templated Mesoporous Silica). Removal of the anionic surfactant by extraction led to the functionalized AM

Discrete mesoporous silica nanospheres (MSNSs) with a narrow size distribution were prepared by a newly developed method, which is based on the emulsion system containing Si(OEt)4 (TEOS), water, cationic surfactant, and basic amino acid under weakly basic conditions (pH 9−10). The average 20 nm sized discrete MSNSs have uniform craterlike mesopores about 3 nm in diameter. The size of the discrete spheres can be regulated in the range of 15−200 nm by, for example, changing the stirring rate in th

The CHA-type aluminosilicate zeolites were synthesized in the presence of the N,N,N-trimethyl-1-adamantammonium cation from different starting materials, including fumed silica, aluminum hydroxide, and the FAU-type zeolite, with their proportions varied. In this work, the proportion of “Q4(nAl)”, Si(OSi)4-n(OAl)n and “Q3(nAl)”, Si(OSi)3-n(OH)(OAl)n, in the total framework Si atoms, which can be estimated by the solid-state 29Si MAS NMR technique, has been applied to an index for Al distribution.

The use of pentaerythritol in combination with the Na cation in the synthesis of ZSM-5 led to a unique Al distribution in the MFI framework; Al atoms were preferentially located at straight and sinusoidal channels, not the intersection.