Silica mesoporous body and process for preparing same

Details Silica mesoporous body and process for preparing same Silica mesoporous body and process for preparing same

1998-10-13

2001-01-16

Bell, Mark L. (Department: 1755)

Chemistry of inorganic compounds

Zeolite

Organic compound used to form zeolite

C423S716000, C423S326000, C423S328100, C423S328200, C423S335000, C501S080000, C501S081000

Reexamination Certificate

active

06174512

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to a mesoporous silica material and to a method of producing same. More specifically, the present invention is directed to a mesoporous silica material (mesoporous silica spheres) having both regularly distributed uniform pores and a regular morphology.
Since 1992 in which MCM-41 was discovered by Mobil Corporation, a great number of studies pertaining to mesoporous materials have been reported. There are recent reports suggesting a possibility of the formation of regularly distributed mesospores and, at the same time, the control of a structure of a micron or millimeter scale on the basis of the above synthesis method. For example, (1) by controlling a mixing ratio of a surfactant to water and a rate of condensation of silica under highly alkaline conditions, a mesoporous silica material which is in a hollow fibrous state having a diameter of 3 &mgr;m and a length of 20 &mgr;m and which has a shell portion wherein cylindrical mesopores are arranged in a honeycomb-like state is produced. (2) Also produced are sheet-like or hollow spherical porous silica particles having a macro-morphology of a micron order, depending upon a speed of stirring a hydrochloric acid-containing, aqueous CTAB (cetyltrimethylammonium bromide) solution at the time of dropwise addition of mesitylene-containing tetraethyl orthosilicate (TEOS) thereto. (3) Porous silica hard spheres having a particle size ranging from 0.1 to 2 mm are produced by adding tetrabutyl orthosilicate (TBOS) to an aqueous solution containing CTAB and NaOH and by stirring the mixture.
The above mesoporous silica materials have drawbacks with respect to the preparation methods thereof, because the reaction steps are complicated and because a long reaction time is required. Additionally, in (1), there is a defect in the pore structure thereof, because a film-like substance having mesopores changes into a cylindrical form. Moreover, it is not possible to suppress crystallization of fine particles. In (2), it is difficult to efficiently obtain uniform spherical particles, because the macro-morphology of the mesoporous silica materials is sensitive to the stirring speed. Thus, addition of mesitylene is required. In (3), there is a problem that TEOS is not able to be used.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide mesoporous silica materials which have overcome the problems of the conventional techniques and a method of producing same. Another object of the present invention is to provide mesoporous silica hard spheres having spherical macro-morphology having a micron order size and, at the same time, regularly distributed pores. It is a further object of the present invention to provide a method of producing mesoporous silica materials, which can control not only the pore structure but also the regularity of the macro-morphology. It is yet a further object of the present invention to provide a method which can produce mesoporous silica materials at room temperature within a short period of time.
In accordance with the present invention there is provided a method of producing a mesoporous silica material, comprising reacting, with stirring, a liquid mixture containing a tetraalkyl orthosilicate, a linear alkylamine, an inorganic acid and water, and drying and thermally treating the thus obtained solid product, wherein said inorganic acid, said alkylamine and said water are present in amounts of 0.05-0.6 mol, 0.2-1.0 mol and 10-100 mol, respectively, per mol of said tetraalkyl orthosilicate.
The present invention also provides mesoporous silica hard spheres having an average pore diameter of 1.5-4 nm and a volume average diameter of 40-80 &mgr;m. The mesoporous silica hard spheres may contain metal components other than silica.
The mesoporous silica materials according to the present invention can be suitably used as shape-selective catalysts, as adsorbing, separating and storing agents for useful gas or ions, as separating and adsorbing agents for harmful gases or ions and as catalysts decomposition of harmful gases or ions.


REFERENCES:
patent: 5112589 (1992-05-01), Johnson et al.
patent: 5128114 (1992-07-01), Schwartz
patent: 5712402 (1998-01-01), Pinnavaia et al.
Schacht et al. “Oil-Water Interface Templating of Mesoporous Macroscale Structures,” Science, vol. 273, pp. 768-771, Aug. 1996.
Tanev et al., “Titanium-Containing Mesoporous Molecular Sieves for Catalytic Oxidation of Aromatic Compounds,” Nature, vol. 368, pp. 321-323, Mar. 1994.
Huo et al., “Preparation of Hard Mesoporous Silica Spheres,” Chem. Mater., vol. 9, pp. 14-17, 1997.

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