Chemistry of inorganic compounds – Silicon or compound thereof – Oxygen containing
Reexamination Certificate
1998-02-11
2001-07-03
Hendrickson, Stuart (Department: 1754)
Chemistry of inorganic compounds
Silicon or compound thereof
Oxygen containing
C423S326000, C423S330100, C502S263000
Reexamination Certificate
active
06254845
ABSTRACT:
DISCLOSURE OF THE INVENTION
The present invention relates to a novel method for manufacturing spherical hollow silicate clusters that can be used as adsorbents of hazardous substances; deodorants; catalyst carriers; humidity adjustors for automatically controlling the humidity of living rooms, car interiors, and other living environments; drug microcapsules; and other applications in which high specific surface is utilized and which have excellent water resistance, heat resistance, corrosion resistance, ion-exchange capacity, and adsorption capabilities.
BACKGROUND OF THE INVENTION
Nanometric fine particles are being studied in electronics, chemistry, machine metal industry, and other fields. Of particular interest for these industries are clusters representing aggregates of several thousand molecules, and superfine clusters comprising anywhere from several to several hundred atoms. The issue of controlling the synthesis, surface improvement, and fine structure of such nanometric fine particles occupies an important position in the aforementioned fields. There are, however, no reports on established methods for synthesizing hollow spherical particles of nanometric size capable of being used for microcapsules and the like.
Naturally occurring aluminosilicates shaped as hollow spheres are known as weathered volcanic glass, but precision techniques such as high-efficiency, high-purity separation/extraction have not yet been established for obtaining such fine particles, and additional research is being conducted.
An attempt has also been made to artificially synthesize amorphous aluminosilicate clusters shaped as such hollow spheres (Wada, S., Nendo Kagaku, Vol. 25, No. 2, pp. 53-60, 1985), but successful results can only be obtained when the starting material is a solution diluted to about 2-4 mmol, which is disadvantageous because the resulting yield is very low, the purity of the product is also low due to the formation of by-products, and the like. A synthesis method has also been proposed for raising the concentration of nanotubular silicates called imogolite to 60 mmol by making use of organosilicon and aluminum compounds (GB Patent 1,574,954 and U.S. Pat. No. 4,252,779) , but there are no examples in which hollow spherical particles are synthesized in high concentrations.
The concentration of starting materials and the acidity or basicity of solutions must be taken into account in order to synthesize hollow spherical silicate clusters having such compositions or structures.
According to a conventional technique, a sodium hydroxide solution is added to a mixture of a monomer silicic acid compound solution (2 mmol or lower) and an aluminum compound solution (0.5-4 mmol) such that the NaOH/Al ratio is 3.0 in order to control the rate of polymerization, and the system is kept at 100° C. for about 5 days, yielding a hollow spherical silicate.
The aforementioned synthesis techniques are incapable of yielding such materials with high efficiency because of the conventional notion that amorphous silica or a hydroxide (boehmite, gypsite, or the like) precipitates first unless the starting materials are gradually mixed in a low concentration under near-equilibrium conditions, and the pH is slowly neutralized with an alkali.
SUMMARY OF THE INVENTION
The present invention provides a method for the homogenous and highly efficient synthesis of an aluminosilicate material that can be used for adsorbents, deodorants, catalyst carriers, humidity adjustors, and the like.
The present invention relates to a method for manufacturing spherical hollow silicate clusters, comprising steps of mixing a solution of a silicon compound and a solution of an aluminum compound or transition metal compound, each with a solution concentration of 10-1000 mmol, rapidly or simultaneously at a rate of 1-10,000 mL/min, removing a salt formed as a by-product, and then subjecting the mixture to hydrothermal synthesis to yield the silicate clusters.
DETAILED DESCRIPTION OF THE INVENTION
It is an object of the present invention to provide a method in which high-concentration starting materials are used to manufacture, with high efficiency, purity, and yield, homogeneous and highly pure hollow spherical silicate clusters that can be used as adsorbents of hazardous substances; deodorants; catalyst carriers; humidity adjustors for automatically controlling the humidity of living rooms, car interiors, and other living environments; drug microcapsules; and other applications having excellent water resistance, heat resistance, and corrosion resistance.
Aimed at attaining the stated object, the present invention resides in a method for producing spherical hollow silicate cluster characterized in the steps comprising of mixing a solution of a silicon compound and a solution of an aluminum compound or transition metal compound, each with a solution concentration of 10-1000 mmol, rapidly or simultaneously at a rate of
1-10,000
mL/min, removing a salt formed as a by-product, and then subjecting the mixture to hydrothermal synthesis to yield the silicate cluster.
In addition, the following methods are preferred embodiments of the present invention: a method for producing the aforementioned spherical hollow silicate cluster in which the composition of superfine particles shaped as hollow spheres and synthesized by using silicon compounds, aluminum compounds, or transition metal compounds as starting materials consists of one or more components selected from the group composed of silicates, aluminum, and transition metal elements; a method for producing the aforementioned spherical hollow silicate cluster in which the mean particle diameter of the spherical silicate particles constituting the clusters falls within a range of 1-10 nm, and the specific surface thereof, as measured by nitrogen adsorption, is 50m
2
/g or greater; and a method for producing the aforementioned spherical hollow silicate cluster in which the silicon/aluminum or transition metal compound molar ratio is 0.5-5.0.
In the past, a solution of a silicate cluster and a solution of an aluminum compound or transition metal compound were slowly mixed in low concentrations. The present invention, however, adopts steps in which a solution of an alkali silicon compound and a solution of an aluminum compound or transition metal compound, each with a solution concentration of 10-1000 mmol, are mixed rapidly or simultaneously and a salt formed as a by-product is removed in order to (1) mix the silicon, aluminum, and transition metal compounds while neutralizing the system with the aid of the alkali silicon compound, and (2) use high-concentration starting solutions while preventing amorphous silica from precipitating by rapidly mixing these components. The corresponding silicon/aluminum or transition metal compound ratio should be about 0.5-5.0. The system is subsequently heated and aged, yielding a material in which the particle diameter is adjusted to 1-10 nm and in which the composition of the silicate material shaped as hollow spheres consists of one or more components selected from the group composed of aluminosilicates and transition metal elements.
In the present invention, silicon compounds, aluminum compounds, and transition metal compounds may be used in order to obtain a homogeneous silicate materials shaped as hollow spheres. Examples of reagents that can be used as silicon sources include sodium orthosilicate, alkyl orthosilicates, sodium metasilicate, and silicon dioxides in the form of amorphous colloids (such as aerogels and the like). These silicate compounds may be used individually or as combinations of two or more compounds.
Examples of inorganic compounds linked to the aforementioned silicate molecular aggregates in accordance with the present invention include aluminum chloride, sodium aluminate, aluminum hydroxide, and other aluminum compounds; organometallic compounds; and chloride, sulfide, hydroxide, nitrate, and other compounds of vanadium, iron, tungsten, titanium, cobalt, nickel, copper, zirconium, and other transition metals. These inorgan
Kakuto Yasuko
Ohashi Fumihiko
Wada Shin-Ichiro
Agency of Industrial Science and Technology
Hendrickson Stuart
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
LandOfFree
Synthesis method of spherical hollow aluminosilicate cluster does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Synthesis method of spherical hollow aluminosilicate cluster, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Synthesis method of spherical hollow aluminosilicate cluster will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2463766