JPS6236015A - Heat resistant silica gel and its production - Google Patents

Abstract

PURPOSE:To provide a silica gel which consists of specific laminar SiO2 and water and has a smaller specific surface area and less deteriorated surface activity even in a high-temp. atmosphere by using a specific aq. soln. to form a silicic acid layer on the non-crystalline SiO2 obtd. by subjecting Mg siliceous ore powder. CONSTITUTION:This heat-resistant silica gel consists of the laminar SiO2 and water having the laminar 6-membered cyclic skeleton by SiO2 and water, has >=99wt% SiO2 among the components except the loss on heating and has >=150m<2>/g specific surface area in a <=1,000 deg.C temp. atmosphere. Such gel is obtd. by first bringing the Mg siliceous ore powder and acid into contact with each other to obtain the non-crystalline SiO2 having much hydroxyl group on the surface. Such SiO2 and the aq. soln. of the salt contg. an element having >=1.0 electronegativity are added to an aq. alkaline metallic silicate soln. The silicic acid layer is thereby formed with the above-mentioned non-crystalline SiO2 as the nucleus and the intended silica gel is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a silica gel with excellent heat resistance and a method for producing the same.

[Conventional technology and its problems]

Amorphous water-reusing silicon oxide is generally called silica gel,
It is widely used as an adsorbent and catalyst.

This silica gel is produced using an aqueous solution (water glass) of an alkali metal silicate such as sodium silicate as a starting material, which is neutralized with an inorganic acid such as hydrochloric acid or nitric acid or an organic acid such as acetic acid or formic acid to precipitate it.

It is obtained by washing with water and drying. In addition, when this is used as a catalyst, the resulting granular or powdered material is often used after further activation by applying reduced pressure and heat treatment.

However, when silica gel produced by this conventional method is placed in a high-temperature atmosphere, sintering easily occurs, and its specific surface area, number of surface active sites, and strength deteriorate significantly. The field was limited.

On the other hand, using clay mineral as a starting material, it is treated with acid to modify its surface.7. Attempts have been made to utilize this as a catalyst (Japanese Unexamined Patent Application Publication No. 54-51099).However, what was obtained by this method.

Because sufficient surface activity is not obtained and impurity components other than silicon oxide, such as magnesium (M) and aluminum (Al), are contained, relatively low temperature (600 ~
700°C), it transforms into another phase, and its thermal properties cannot be said to be sufficient.

Therefore, the inventors of the present invention conducted intensive research to solve the problems of the conventional techniques as described above, and as a result of various systematic experiments, they came up with the present invention.

[Purpose of the invention]

An object of the present invention is to provide a stable heat-resistant silica gel with a small decrease in specific surface area and high 2-surface activity even in a high-temperature atmosphere, and a method for producing the same.

[Structure of the invention]

The heat-resistant silica gel of the present invention is characterized by having a layered silicon dioxide having a layered hexagonal skeleton made of silicon dioxide and a specific surface area of 1501 i/i or more in an atmosphere of skin. U) The method for producing heat-resistant silica gel of the present invention comprises an acid treatment step of contacting magnesium silicate expanded powder with an acid to obtain amorphous silicon dioxide having a large amount of hydroxyl groups on the surface, and an alkali metal A silicate layer generation step of adding an aqueous solution of a salt containing the amorphous silicon dioxide and 0 or more elements of IC yield to the silicate aqueous solution to generate a silicic acid layer using the amorphous silicon dioxide as a core. (hereinafter referred to as the second invention).

The method for producing heat-resistant silica gel of the present invention involves contacting magnesium silicate expanded powder with an acid to obtain amorphous silicon dioxide having a large amount of hydroxyl groups on the surface.An aqueous salt solution is added to the amorphous silicon dioxide to form a nucleus. A silicic acid layer forming step for forming a silicic acid layer as a silicic acid layer, and a heating step for activating the product by heating it in a temperature range of 400 to 1000°C (hereinafter referred to as the second book). three inventions).

The method for producing heat-resistant silica gel of the present invention includes an acid treatment step in which a magnesium silicate expanded powder is brought into contact with an acid to obtain amorphous silicon dioxide having a large amount of hydroxyl groups on the surface; This method is characterized by a silicate layer generation step in which an aqueous solution of a salt containing an impurity removing element is added to remove substances that impair heat resistance, and a silicate layer is generated using the amorphous silicon dioxide as a nucleus. (below.

(hereinafter referred to as the fourth invention).

The method for producing heat-resistant silica gel of the present invention includes an acid treatment step of contacting magnesium silicate expanded powder with an acid to obtain amorphous silicon dioxide having a large amount of hydroxyl groups at the top; A silicic acid layer forming step in which a silicic acid layer is formed using the amorphous silicon dioxide as a nucleus by adding an aqueous solution of a salt containing impurity removing elements that impair the heat resistance contained in the product, and It is characterized by comprising a heating step of heating and activating in a temperature range of 1000°C (hereinafter referred to as the 2nd invention and the 3rd invention).U Below, the structure of the 9th invention will be explained in more detail. .

The heat-resistant silica gel in the first invention is composed of layered silicon dioxide having a layered six-membered ring skeleton made of silicon dioxide and water. The silicon dioxide skeleton present in this layered silicon dioxide is one in which the magnesium silicate expanded silicon dioxide skeleton (silicon dioxide skeleton of phyllosilicate) as a starting material remains.

In addition, this silica gel contains silicon dioxide (8i0.) of 99 ωt % or more among components other than ignition loss. This is because, among cations other than hydrogen, 99ωt91yThis heat-resistant silica gel has the remains of the phyllosilicate mineral as a raw material, and is confirmed by an electron microscope to exhibit a nine-layered or band-like shape.

This is different from conventional silikage which is in two grains.

Large surface area available.

The size of this band or layer is determined by the crystal size of the raw mineral, and two particles with uniform diameters are obtained. Unlike granular silica gel, there is a large area for physical bonding between particles.

It has the characteristic that it is easy to obtain particles with controlled secondary pore diameters.

In addition, components other than silicon 9 such as magnesium (Ml)
Since it does not contain any ions, crystallization due to the action of these ions does not proceed. Therefore, compared to minerals themselves or minerals activated with acids, they can be used stably without changing their structure even at high temperatures.

Furthermore, although the part of the structure in which ions such as the raw material magnesium (Ml) are involved is destroyed, the part in which silicon (8i) is involved remains intact.

8i0. It is thought that the six-membered ring skeleton formed by combining the tetrahedra remains. Therefore, unlike conventional silica gel, which is an aggregate of fine particles in which 8i04 tetrahedra are bonded together in a disordered manner, it is difficult to rearrange the atoms, so it has excellent heat resistance. Such structural differences can be easily confirmed by the difference in shape using a microscope and by X-ray diffraction. In X-ray diffraction, it has been thought that only results similar to those of conventional silica gel can be obtained. However, subtle but clear differences were observed between the small-angle scattering band and the low-angle scattering band and the position of the first peak, and this reflects the above-mentioned structural difference. It is thought that

Next, the method for producing the heat-resistant silica gel of the second invention will be explained in detail. The method for producing heat-resistant silica gel according to the second invention involves first contacting magnetic screw and ram silicate expanded powders (including granular ones) of a desired size with an acid to form an amorphous material having a large amount of hydroxyl groups on the surface. Obtain silicon dioxide (hydrated silicon dioxide) (acid treatment step).

The magnesium silicate expanded powder used in this acid treatment step is obtained by crushing the magnesium silicate expanded material into a desired size and shape.

Here, the magnesium silicate compound is a hydrated magnesium silicate clay mineral that is a phyllosilicate containing magnesium (Ml) that is easily eluted in acids, and specifically has a layered ribbon structure such as sepiolite and palygorskite. Examples include fibrous clay minerals, tartar, chlorite, vermiculite, etc.

Among them, sepiolite is popular due to its reactivity and shape.

Preferably it is a clay mineral.

This is a fibrous clay mineral with a layered ribbon structure.

It is a clay mineral whose main component is hydrated magnesium silicate and has highly reactive hydroxyl groups on its surface. In addition, this clay mineral consists of fibers with a diameter of about α005 to 16 μm, and there are pores (channels) parallel to the fibers with a rectangular cross section of about 10 to 6 A, and they can be submerged in water. This fiber has the property of being easily dispersed. In addition, in this clay mineral, a part of magnesium or silicon is aluminum, iron,
In some cases, it is substituted with nickel, sodium, etc.

Specifically, sepiolite (5epiolite) whose main component is hydrated magnesium silicate, Xylotile (Xylotile), ? 7 Linai) (Loug
hlinite), 71iv-x ndhui) (Fa
lcondoite) + palygorskite (Pαlygors) whose main component is hydrated aluminum silicate
kite), etc., and one or a mixture of two or more of these is used. In addition, these items are 400 to 800
A material calcined within the temperature range of 0° C. may also be used.

'The only common name is Mountain Cork (Atuntα1n).
cork), Mountain Wood (M-:unt/Lin
wood).

Mountain leather (MAuntrzin 1erth)
er), sepiolite (Meers-chlLum),
Minerals called attapulgite (Attapulgite, e) and the like fall under this category.

These magnesium silicate expansions can be crushed by volatilization in a mortar or the like, or by using a mixer, ball mill, dynamic mill, bottle mill, etc.
This is done by wet or dry pulverization using a jet mill, beater, etc.

This pulverization is preferably carried out to the extent that the fibrous shape of the mineral remains, and the pulverization is preferably carried out to the extent that the fibrous shape of the mineral remains. is preferred.

The purpose of this pulverization is to increase the pulverization efficiency.

Other inorganic powders, such as powders of alumina, silica gel, hydroxide, magnesium hydroxide, dolomite, calcium carbonate, etc., may be added for pulverization.

In fact, the acid used in this acid treatment step is the magnesium salt produced as a result of the reaction. It is preferable that the solubility in water is so high that excess substances (substances that adversely affect heat resistance) can be removed in the post-processing process. Specifically, there are aqueous solutions of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, etc., and mixtures thereof.The concentration of this acid is not particularly limited, but it should be 3 normal (N) or higher. When used.

The amount of acid used in this acid treatment is preferably an aqueous solution of the above-mentioned acid in which at least 2 moles (rnol) or more of the acid is dissolved per 100 y of magnesium silicate mineral powder. . This amount is
This is because an amount sufficient to remove magnesium (Mf) in this step is sufficient, and if magnesium remains in the final product, it will not be possible to obtain a product with excellent thermal properties.

Methods of acid treatment include immersion in these acid aqueous solutions, or hot flaking using a ball mill, which can also be carried out at the same time as the acid-treated hot flakes and the crushing of the magnesium silicate expansion. can.

Next, an aqueous solution of hydrated silicon dioxide (non-crystalline silicon dioxide having a large amount of hydroxyl groups on the surface) and a salt containing an element with an electronegativity of 1.0 or more is added to the aqueous alkaline metal silicate solution. A silicic acid layer is generated using the hydrated silicon dioxide as a nucleus (silicic acid layer generation step).

Here, the aqueous solution of alkali metal silicate has the general formula M20
-nSiO, (M is an alkali metal or ammonium,
It is a liquid water-containing water glass composed of an alkali metal silicate (n is a number from 1.0 to 55) and water. As the alkali element of this alkali silicate, for example, lithium (Li) is used.

Alkali metals such as sodium (Nα), potassium (K), wvigilum (ab) and ammonium (
NEI, ) etc. are used. Particularly, when the alkali element is sodium, potassium, etc., it is preferable because it is inexpensive and easily available. Also, alkali metal silicates (M.

0・口8i0,)の! 1, that is, the molar ratio with M,0,:8i0 mushrooms is 1.0 to 53. This value is 6.5
If it exceeds 8i0, it may be soluble in water.

This is not preferable because the molecular weight of the compound becomes large. Furthermore.

This water glass has a solid content of (M,0-nsiO
! ) with a weight of about 11 to 40% by weight (ωt%). Among them, it is more preferable that it is 100% or less. When using water glass in this range,
Workability is excellent, and water glass in this range is easily available.When exceeding u40ωL%, 8i0!
An aqueous solution of a salt containing an element with an electronegativity of 1.0 or more is produced when the amount of hydrated silicon dioxide becomes too large, producing a product that is not affected by the hydrous silicon dioxide as a nucleus, making it difficult to obtain a product with excellent heat resistance. Acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid and mixtures thereof, calcium (Cα), magnesium (Mf), aluminum (Aβ), iron (Fe), cobalt (CO), nickel (Nl), copper (Cu ), platinum (Pt), diconium (Zr), zinc (Zn).

Manganese (Mh), chromium (Or), silver (Ay)
Use an aqueous solution of salt containing. Furthermore, as this aqueous solution,
When a compound other than an acid is used, it is necessary to carry out acid treatment as a subsequent step of the single step, and adjust the amount of ions so that no substances that impair heat resistance remain.

Here, in this silicate layer generation step, the mixing ratio of the aqueous solution of alkali metal silicate and hydrated silicon dioxide is such that the silicon dioxide (8i0.) component in the aqueous solution of alkali metal silicate is 50y or less per 1f of hydrated silicon dioxide. It is preferable that If this mixing amount exceeds 5ay, it will be difficult to obtain a heat-resistant silica gel that utilizes the structure of the core, and the resulting product will be similar to conventional silica gel. Incidentally, even in this case, it is possible to obtain the heat-resistant silica gel according to the present invention by making the rate of the 2 reactions abnormally slow.

Through the above steps, heat-resistant silica gel is obtained.

The heat-resistant silica gel obtained by this manufacturing method is composed of layered silicon dioxide having a layered six-membered ring skeleton made of silicon dioxide and water, and has a width α of 1 to 2 pm.

It is a band-like or scale-like silica gel with a length of 1 to 20 μm and a thickness of about α001 to 100 μm. This silica gel has a high purity of 9 or more cations other than hydrogen (i.e., a specific surface area of 150 m'/g or more in a temperature atmosphere of 1000"C or less, 2 surface strongest acid strength of 4.8 or less). It has excellent heat resistance.

The method for producing heat-resistant silica gel according to the third invention will now be described in detail.

The method for producing heat-resistant silica gel according to the third invention is as follows.

This method is characterized by further heating and activating the product obtained by the same method as the method for producing heat-resistant silica gel of the second invention.

That is, silicic acid is produced by contacting magnesium silicate expanded powder with an acid and adding an aqueous solution of a salt containing an element on an amorphous diacid having a large amount of hydroxyl groups on the surface to form a silicic acid layer with the amorphous silicon dioxide as a nucleus. A layer forming step and the product at 400~
It consists of a heating step of activating by heating in a temperature range of 1000°C.

Here, the acid treatment step and the silicic acid layer generation step in the second aspect of the third invention are the same as the acid treatment step and the silicic acid layer generation step described in detail in the second aspect of the invention, so a detailed explanation will be omitted.

In particular, the silicic acid layer (heat-resistant silicage/I/) generated in the silicic acid layer generation step is activated by heating within the temperature range of t-, aoo to 1000°C. heat-resistant silica gel) (heating step).

This heat treatment is carried out within a temperature range of 400 to 1000°C to further activate the product obtained in the silicic acid layer forming step to form a heat-resistant silica gel having excellent heat resistance and high activity.

At this time, the heating in the two-step heating step is performed by first completely removing the moisture contained in the product produced in the previous step at a temperature of 100°C or less, and then heating it at a predetermined temperature to activate it. preferable. By carrying out this heating pretreatment, the heat resistance and surface activity of the heat-resistant silica gel obtained can be improved, making it particularly useful for catalysts and the like.

What is the preferred heating temperature in the nine heating steps?

It is within the range of 400 to 8000°C.

Through the above steps, heat-resistant silica gel is obtained.

The heat-resistant silica gel obtained by this manufacturing method is composed of layered silicon dioxide having a layered six-membered ring skeleton made of silicon dioxide and water, and has a width α of 1 to 2 μm.

Length 1~20 pins, thickness [1001~1100 pins]
It is a band-like or scale-like silica gel. This silica gel has a high purity with 94 or more of the cations other than hydrogen being silicon (1) a specific surface area of 150 rtf/I or more in an atmosphere at a temperature of 1000°C or less; 2) the strongest acid strength on the surface;
It has excellent heat resistance of 0 or less.

The method for producing heat-resistant silica gel according to the fourth invention will now be described in detail.

A method for producing heat-resistant silica gel according to the fourth invention.

In the method for producing heat-resistant silica gel of the second invention, before entering the silicic acid layer forming step, substances that impair heat resistance contained in the amorphous silicon dioxide obtained in the acid treatment step are removed. This method is characterized in that a silicate layer generation step is performed after the silicate layer is formed.

That is, an acid treatment step in which magnesium silicate expanded powder is brought into contact with an acid to obtain amorphous silicon dioxide having a large amount of hydroxyl groups on the surface, and a substance contained in the amorphous silicon dioxide that impairs heat resistance is removed. and a silicic acid layer forming step of forming a silicic acid layer in an aqueous alkali metal silicate solution using crystalline silicon dioxide as a core.

Here, the acid treatment step and the silicic acid layer forming step in the fourth aspect of the present invention are the same as the acid treatment step and the silicic acid layer forming step described in detail in the second aspect of the present invention, so a detailed explanation will be omitted.

Next, the impurity removal step is a step of removing substances (impurities) that impair heat resistance contained in the amorphous silicon dioxide obtained in the acid treatment step.

In this impurity removal step, the acid-treated amorphous silicon dioxide is neutralized and then washed with water to remove impurities contained in the amorphous silicon dioxide. At that time, neutralization may be omitted and only water washing may be performed.

This is because the presence of free acid produces unreacted silicon dioxide on the surface of the nucleus, which repels impurities. At this time, impurities are removed by adding a basic substance to the hydrous silicon dioxide obtained by acid treatment to neutralize it, and then washing it with water.
This is done by repeating the first step with water. The acid component of this rlj sweat may be removed by simply using 14 groups and repeating washing and dehydration without neutralization.

The basic substance to be removed is preferably one in which the salt produced by the neutralization reaction is soluble in water, and specifically includes sodium hydroxide, calcium hydroxide, calcium carbonate, magnesium hydroxide, and ammonia.

Examples include amines. Among these, when sodium hydroxide is used, it is effective against all of the problems used in the acid treatment step.

In addition, water washing and dehydration can be done by mixing water with water using a filter press, centrifugal separator, centrifugal filtration, suction filtration machine, etc.
Repeat dehydration.

The impurity-free amorphous silicon dioxide thus obtained was added to an aqueous alkali metal silicate solution, and the electronegativity was further increased to 1.
An aqueous solution of a salt containing 0 or more elements is added to form a silicic acid layer using the hydrous silicon dioxide as a core, thereby obtaining a heat-resistant silica gel according to the present invention.

Through the above steps, heat-resistant silica gel is obtained.

The heat-resistant silica gel obtained by this production method is composed of tJ-shaped silicon dioxide water having a layered six-membered ring skeleton made of silicon dioxide, and has a width of 1 to 2 μm 1N.

It is a band-like or scale-like silica gel with a length of 1 to 20 μm and a thickness of about α001 to 100 μm. This C+)tt gel has a high degree of wear of 9W or more of cations other than hydrogen with silicon (2) The specific surface area in an atmosphere at a temperature of 1000°C or less is 1 sow7y or more 2 The strongest acid strength on the surface is 4.8 or less It has excellent heat resistance.

The method for producing heat-resistant silica gel according to the third aspect of the present invention will be described in detail.

The method for producing heat-resistant silicage according to the third invention is as follows.

This method is characterized by further heating and activating the product obtained by the same method as the method for producing heat-resistant silica gel of the fourth invention.

That is, an acid treatment step in which magnesium silicate expanded powder is brought into contact with an acid to obtain amorphous silicon dioxide having a large amount of hydroxyl groups on the surface, and a substance contained in the amorphous silicon dioxide that impairs heat resistance is removed. a silicic acid layer forming step in which a silicic acid layer is formed in an aqueous alkali metal silicate solution using crystalline silicon dioxide as a nucleus;
It consists of a heating step of activating by heating in a temperature range of 000°C.

Here, the acid treatment step, impurity removal step, and silicic acid layer generation step in the third aspect of the present invention are the same as the acid treatment step, impurity removal step, and silicic acid layer generation step in the fourth aspect of the present invention described above, so a detailed explanation will be given. Omitted.

First, the silicic acid layer (heat-resistant silica gel) produced in the silicic acid layer producing step is activated by heating within a temperature range of 400 to 1000°C. silica gel) (heating step).

This heat treatment is carried out within a temperature range of 400 to 1000°C to further activate the product obtained in the silicic acid layer forming step to form a heat-resistant silica gel having excellent heat resistance and high activity.

At this time, the heating in the nine heating steps is performed by first completely removing the moisture contained in the product produced in the previous step at a temperature of 100°C or less, and then heating it at a predetermined temperature to activate it. preferable. By carrying out this heating pretreatment, the heat resistance and surface activity of the heat-resistant silica gel obtained can be improved, making it particularly useful for catalysts and the like.

What is the preferred heating temperature in the nine heating steps?

It is within the range of 400 to 8000°C.

Through the above steps, heat-resistant silica gel is obtained.

The heat-resistant silica gel obtained by this m-soaking method is composed of layered silicon dioxide having a layered six-membered ring skeleton made of silicon dioxide and water, and has a width of 11 to 2 μm and a length of 1 to 20 μm.
It is a band-like or scale-like silica gel with a thickness of about 1001 to 100 μm. This silica burner has high purity (,100Q'Q
It has excellent heat resistance, with a specific surface area of 150 m/f or less and a maximum acid strength of 1.5 or less per surface under the following temperature atmosphere.

In the second invention to the third invention, when the obtained heat-resistant silica gel is used as a catalyst or an adsorbent, it is preferable to form it into a single granule since it is difficult to use it in powder form. In this case, to make the 1# thermal silica gel into granules in the final product.

The magnesium silicate expanded powder used in the acid treatment step, which is the first step, is heated and
Preferably, it is obtained by firing or sintering. After bonding amorphous silicon dioxide with an aqueous alkali metal silicate solution such as water glass in the silicate layer generation step, 400 to 8
It may be heated to 000° C. and pre-sintered to form granules.

Furthermore.

The obtained powdery heat-resistant silica gel was treated with r-AlzO
Granular silica gel can be obtained by granulation using a binder such as s + silica gel or water glass. Alternatively, acid treatment may be performed after bonding the magnesium silicate expander with a small amount of water glass.

[Operation and effects of the invention]

The heat-resistant silica gel of the present invention is a stable silica gel that exhibits little decrease in specific surface area even under high-temperature atmospheres and has a controlled surface activity.

By the method for producing heat-resistant silica gel of the second to third aspects of the present invention, heat-resistant silica gel that is stable even in a high-temperature atmosphere can be produced easily and at low cost.

The heat-resistant silica gel produced by the production method of the second invention to the third invention is a stable silica gel with a small decrease in specific surface area and high surface activity even in a high-temperature atmosphere.

Although the mechanism by which the heat-resistant silica gel according to the present invention exerts such effects is not yet clear, it is thought to be lacking.

That is, it is thought that the structure and composition of layered silicon dioxide having a layered six-membered ring skeleton made of silicon dioxide present in the heat-resistant silica gel play an important role.

f) Unlike the conventional surface activation of minerals using acids or alkalis, all cations other than silicon and hydrogen ions are removed.

Structural changes due to crystallization of enstatite and forsterite due to the coexistence of other cations, such as magnesium (M9) ions, are unlikely to occur. Moreover.

Since the 8i04 tetrahedral bond of the raw mineral remains unbroken, the 5i-0
Bond rearrangement is less likely to occur. For this reason.

The amorphous structure is maintained and stable even at high temperatures. Furthermore, since the heat-resistant silica gel according to the present invention has a bi-enzymatic structure, the bonding points of oxygen perpendicular to the first layer are severed.

This is thought to be due to the presence of protons etc. in that part. At room temperature, water is further adsorbed to this, reducing the surface activity.However, when it is heated, water is removed, thereby improving the surface activity. In normal silica gel and minerals.

At the same time as this dehydration and activation by heating, atomic rearrangement occurs, resulting in a decrease in surface area and activity. No decrease in surface area or activity was observed, and it is considered to have excellent properties.

〔Example〕

Two aspects of the present invention will be described in detail below.

Example 1 After coarsely crushing β-sepiolite from Turkey using a jaw crusher, a steel bore L/f with a diameter of 10ff was crushed.
Seviolite powder with an average particle size of 10 μm was obtained by pulverizing with a ball mill using T.

Add 100f of this powder to 2e of an aqueous solution of 50N hydrochloric acid for 25 minutes.
It was left for 24 hours at ゛C. This was removed by suction to obtain a water-containing cake. Add 2β water to this.

The mixture was stirred and dispersed using a stirrer equipped with Teflon blades.

While continuing this stirring, sodium silicate (Nttz O
-&38 iox) C14ωL%yJ<molten g woP
H cuff was gradually added until it reached 0. After that, after repeating filtration and water washing, it was dried at 60°C for 10 hours.
Layered silicon dioxide powder (heat resistant S/IJ) according to the present invention
(Sample No. 1) was obtained.

The ingredients of this powder are 8i0. is approximately 80ωt%, scorching heat reduction is approximately 20ωt%, and impurity components such as 1Mg and Nn are 0.
It was less than 1%. The structure and shape of this powder can be determined by electron microscopy w4
It was confirmed by observation and X-ray diffraction that it was different from ordinary silica gel. Also, the specific surface area of this powder is 240 rd
/I, and even after heat treatment at 1000°C for 4 hours, 20
It exhibited excellent heat resistance of 0g/9.

Example Z Powder obtained using the same raw materials and method as Example 1,
Further, heat treatment was performed for 4 hours at the temperature shown in the table to obtain heat-resistant silica gels according to the present invention (sample numbers 2 to 7).

Performance evaluation test of the obtained heat-resistant silica gel.

Regarding the specific surface area, for comparison with the BET method using nitrogen gas, a commercially available Silicab/L/ (product name: Tokuseal: manufactured by Tokuyama Seitatsu) was subjected to the same heat treatment as described above, and the same performance evaluation test was conducted. Ta. The obtained results are also shown in the table (sample numbers 01 to C5).

As is clear from the table, 9 things related to the present invention are as follows.

It can be seen that heat treatment, particularly heat treatment at 400 to 1000'C, yields a heat-resistant silica gel with strong two-surface acid strength and a large specific surface area.

Ii4/Table Example 5 Average particle size 1 obtained by crushing β-Seviolite from Turkey
0 μm Seviolite powder 100f.

It was left in a 50N hydrochloric acid aqueous solution 21 at 25°C for 24 hours. To this was gradually added a suspension of 1 aay of magnesium hydroxide dispersed in water.

Excess hydrochloric acid was neutralized. Then wash and filter.

In the filtrate, chloride ions CC11'') are mixed with silver nitrate (Ap(NO
I)) Repeat the test until it is no longer detected in an aqueous solution.

A water-containing cake (water content: about 40 ωt%) was obtained.

Next, 100 g of this water-containing cake was dispersed in 11 water,
Add water glass No. 3 T-10 (l) to this.

Stir and mix. To this, 11 times of a 10N aqueous solution of magnesium chloride (HTPC6) was added while stirring to obtain a precipitate. After filtering and dehydrating this precipitate.

It was washed twice with 1N hydrochloric acid 51, and further washed with water until the pH of the filtrate became &8. Then after suction filtration.

The layered silicon dioxide powder according to the present invention is dried at 60°C (
Heat-resistant silicage A/) was obtained (sample number 8).

The specific surface area of this powder was approximately 17 o vl/9.

When this was further heated at 8000°C for 5 hours, the heat-resistant silica gel obtained had a specific surface area of 15 o i/f.

The strongest acid strength on the surface was -5.6.

Example 4 Average particle size 1 obtained by crushing β-sepiolite from Turkey
100g of Sepiolai 1 powder of 0 μrn.

Leave it in 50N hydrochloric acid aqueous solution 21 at 25°C for 24 hours,
Acid-treated sepiolite was obtained by suction filtration. Next, use a 10-fold diluted aqueous solution of commercially available water glass No. 3.

An amount of acid-treated sepiolite shown in Table 2 was added and mixed with 50 g of silicon dioxide (5iOi) in an aqueous solution, and the mixture was maintained at about 2°C. In addition, this mixture was further cooled to 2°C while stirring using a Teflon stirrer.
1N hydrochloric acid was added to precipitate neutralized silica gel.

After suction filtration, water from Step 11 was added and mixed, followed by suction filtration. This filtration and washing with water was carried out until chlorine ions in the filtrate were no longer detected by adding an aqueous silver nitrate solution. after that.

After drying at 80°C for 48 hours, heat treatment was further performed at 600°C for 4 hours to obtain heat-resistant lizards according to the present invention (sample numbers 9 to 12). The performance evaluation test results of the obtained silica gel are shown in Table 2.

Examples & A powder obtained by coarsely pulverizing Seviolite from Turkey (average particle size 5 ff) was heat-treated at 650'C for 1 hour. This was acid-treated by immersing it in a 3N aqueous solution of 4C hydrochloric acid for 72 hours, then neutralized with a 1N hydroxide solution, washed with water and filtered repeatedly, and dried. Furthermore, the obtained granular material was heat-treated at 8000 ° C. for 4 hours to obtain a heat-resistant silica gel according to the present invention (sample number 14).
This silica gel.

The specific surface area was 200 i/g9 and the strongest acid strength on the surface was -56.

Example 1 Average particle size 1 obtained by crushing β-sepiolite from Turkey
0 μm sepiolite powder 100 mm f 50 N hydrochloric acid aqueous solution 21 was allowed to stand at 25° C. for 24 hours and filtered under suction to obtain acid-treated sepiolite powder. First, 9 powder obtained was added to a 10-fold diluted solution of commercially available water glass No. 5 at a ratio of 20F to 10 g of silicon dioxide (8i0.) component in the water glass, and magnesium chloride (#011*) was added. Table 2 shows examples & American palygorskite powder (average particle size α5 μm).
was immersed in a 5.0N hydrochloric acid aqueous solution 21 for 7 days. After suction filtration once, the obtained water-containing cake was poured into water 11 and dispersed using a mixer. A 10-fold diluted solution of commercially available water gaff No. 13 was gradually added to this mixture to neutralize it, and the filtration and water washing was repeated a9 times, and the obtained product was dried at 80°C and dried at 700°C. A heat-resistant silica gel according to the present invention was obtained by heat treatment for a period of time (sample number 13).The obtained silica gel had a specific surface area of 180 m/f and a surface strongest acid strength of -5.6.

It was added until the pH became &0. After filtering this.

Suspend in water 11, add 2N hydrochloric acid to pH
was set as 5. Next, after washing with water, filtering, and drying.

Further, heat treatment was performed at 400° C. for 4 hours to obtain a heat-resistant silica gel according to the present invention (sample number 15). The obtained silica gel has a specific surface area of about 300 g/f.

The strongest acid strength on the surface was 1.5.

Examples & α-Sebiophyto powder from Spain (average particle size 2 μm)
1001 and commercially available water glass No. 3 (N~0・58101
1 aay of O4006% aqueous solution) and 300 g of water were added and mixed in an alumina mortar. This was placed in a polyethylene container and dried at 80"C for 24 hours. 100f of the obtained granular material was immersed in a 1.0 N sulfuric acid aqueous solution 11 for 7 days to perform acid treatment. Specified hydroxide
- Neutralize with IJum aqueous solution, repeat water washing and filtration, 8
The granular material obtained by drying at 0°C was heat-treated at 8000°C for 2 hours to obtain a heat-resistant silica gel according to the present invention (sample 11116). The obtained silicage/l/ has a specific surface area of 200d/9. The strongest acid strength on the surface was -5.0.

Claims (1)

[Scope of Claims] (1) Consisting of layered silicon dioxide having a layered six-membered ring skeleton made of silicon dioxide and water, silicon dioxide is 99 ωt% or more of the components other than ignition loss, and the temperature atmosphere is 1000°C or less A heat-resistant silica gel having a specific surface area of 150 m^2/g or more. (2) An acid treatment step in which the magnesium silicate expanded powder is brought into contact with an acid to obtain amorphous silicon dioxide having a large amount of hydroxyl groups on the surface, and the amorphous silicon dioxide is added to an aqueous alkali metal silicate solution and the electronegativity is 1. A method for producing heat-resistant silica gel, comprising the step of forming a silicic acid layer by adding an aqueous solution of a salt containing .0 or more elements to form a silicic acid layer using the amorphous silicon dioxide as a core. (3) The magnesium silicate expanded substance is one or a mixture of two or more of hydrous magnesium silicate clay minerals such as sepiolite, palygorskite, talc, chlorite, and vermiculite.
) The method for producing heat-resistant silica gel as described in section 2. (4) Magnesium silicate mineral powder is obtained by heating/calcining or sintering the granular material obtained by pulverizing magnesium silicate expanded material in a temperature range of 400 to 8000°C before or after the pulverization. The particle size of the granules is 10
The method for producing heat-resistant silica gel according to claim (2), wherein the thickness is 0 μm to 10 mm. (5) The aqueous alkali metal silicate solution has the general formula M_2O.
nSiO_2 (M is alkali metal or ammonium,
The method for producing heat-resistant silica gel according to claim (2), wherein the aqueous solution is an aqueous solution of an alkali metal silicate represented by (n represents a numerical value of 1.0 to 3.3). (6) The aqueous solution of a salt containing an element having an electronegativity of 1.0 or more is an acid such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, or a mixture thereof. A method for producing heat-resistant silica gel. (7) Aqueous solutions of salts containing elements with electronegativity of 1.0 or higher include calcium (Ca), magnesium (Mg), aluminum (Al), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), platinum (Pt), zirconium (Zr), zinc (Zn), manganese (Mn), chromium (Cr), and silver (Ag). (2) The method for producing heat-resistant silica gel as described in section (2). (8) Acid treatment step of contacting magnesium silicate mineral powder with acid to obtain amorphous silicon dioxide having a large amount of hydroxyl groups on the surface, and adding the amorphous silicon dioxide to an alkali metal silicate aqueous solution and having an electronegativity of 1. A silicic acid layer forming step of adding an aqueous solution of a salt containing 0 or more elements to form a silicic acid layer using the amorphous silicon dioxide as a core;
A method for producing heat-resistant silica gel, comprising a heating step of activating it by heating in a temperature range of °C. (9) The magnesium silicate mineral is one or a mixture of two or more of hydrous magnesium silicate clay minerals such as sepiolite, palygorskite, talc, chlorite, and vermiculite.
) The method for producing heat-resistant silica gel as described in section 2. (10) Magnesium silicate mineral powder is obtained by heating/calcining or sintering granules obtained by pulverizing magnesium silicate minerals at a temperature range of 400 to 800°C before or after the pulverization. is a granular material, and the particle size of the granular material is 1
The method for producing heat-resistant silica gel according to claim (8), wherein the thickness is 00 μm to 10 mm. (11) The aqueous alkali metal silicate solution has the general formula M_2O
・Claim (8), which is an aqueous solution of an alkali metal silicate represented by nSiO_2 (M is an alkali metal or ammonium, n is a numerical value of 1.0 to 3.3) The method for producing the heat-resistant silica gel described. (12) The aqueous solution of the salt containing an element having an electronegativity of 1.0 or more is an acid such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, or a mixture thereof. A method for producing heat-resistant silica gel. (13) Aqueous solutions of salts containing elements with electronegativity of 1.0 or more include calcium (Ca), magnesium (Mg), aluminum (Al), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), platinum (Pt), zirconium (Zr), zinc (Zn), manganese (Mn), chromium (Cr), and silver (Ag). The method for producing heat-resistant silica gel according to item (8). (14) Acid treatment step of contacting magnesium silicate mineral powder with acid to obtain amorphous silicon dioxide having a large amount of hydroxyl groups on the surface, and removing substances contained in the amorphous silicon dioxide that impair heat resistance. an impurity removal step, and an aqueous solution of a salt containing the amorphous silicon dioxide from which impurities have been removed and an element having an electronegativity of 1.0 or more is added to an alkali metal silicate aqueous solution to form a silicic acid layer using the amorphous silicon dioxide as a core. 1. A method for producing heat-resistant silica gel, comprising a step of producing a silicate layer. (15) The magnesium silicate mineral is one or a mixture of two or more of hydrated magnesium silicate clay minerals such as sepiolite, palygorskite, talc, chlorite, and vermiculite.
14) The method for producing heat-resistant silica gel as described in item 14). (16) Magnesium silicate mineral powder is obtained by heating/calcining or sintering granules obtained by pulverizing magnesium silicate minerals at a temperature range of 400 to 800°C before or after the pulverization. It is a granular material, and the particle size of the granular material is 10
The method for producing heat-resistant silica gel according to claim (14), wherein the thickness is 0 μm to 10 mm. (17) The aqueous alkali metal silicate solution has the general formula M_2O
- Claim (14) characterized in that it is an aqueous solution of an alkali metal silicate represented by nSiO_2 (M is an alkali metal or ammonium, n is a numerical value of 1.0 to 3.3) The method for producing the heat-resistant silica gel described. (18) Claim No. 14, characterized in that the aqueous salt solution containing an element with an electronegativity of 1.0 or more is an acid such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, or a mixture thereof.
2. Method for producing heat-resistant silica gel as described in Section 1. (19) Aqueous solutions of salts containing elements with electronegativity of 1.0 or more include calcium (Ca), magnesium (Mg), aluminum (Al), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), platinum (Pt), zirconium (Zr), zinc (Zn), manganese (Mn), chromium (Cr), and silver (Ag). (14) The method for producing heat-resistant silica gel as described in item (14). (28) Acid treatment step of contacting magnesium silicate expanded powder with acid to obtain amorphous silicon dioxide having a large amount of hydroxyl groups on the surface, and removing substances that impair heat resistance contained in the amorphous silicon dioxide. A silicate layer is formed by adding an aqueous solution of a salt containing the amorphous silicon dioxide from which impurities have been removed and an element having an electronegativity of 1.0 or more to an alkali metal silicate aqueous solution and using this amorphous silicon dioxide as a core. A silicic acid layer generation step of producing 400 to 1000
A method for producing heat-resistant silica gel, comprising a heating step of activating it by heating in a temperature range of °C. (21) The magnesium silicate mineral is one or a mixture of two or more of hydrous magnesium silicate clay minerals such as sepiolite, palygorskite, talc, chlorite, and vermiculite.
20) The method for producing heat-resistant silica gel as described in item 20). (22) Magnesium silicate mineral powder is obtained by heating/calcining or sintering granules obtained by pulverizing magnesium silicate minerals at a temperature range of 400 to 800°C before or after the pulverization. is a granular material, and the particle size of the granular material is 1
The method for producing heat-resistant silica gel according to claim (20), wherein the thickness is 00 μm to 10 mm. (25) The aqueous alkali metal silicate solution has the general formula M_2O
・Claim (20) is characterized in that it is an aqueous solution of an alkali metal silicate represented by nSiO_2 (M is an alkali metal or ammonium, and n is a numerical value of 1.0 to 3.3) The method for producing the heat-resistant silica gel described. (24) Claim No. 20, characterized in that the aqueous solution of a salt containing an element with an electronegativity of 1.0 or more is an acid such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, or a mixture thereof.
2. Method for producing heat-resistant silica gel as described in Section 1. (25) Aqueous solutions of salts containing elements with electronegativity of 1.0 or more include calcium (Ca), magnesium (Mg), aluminum (Al), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), platinum (Pt), zirconium (Zr), zinc (Zn), manganese (Mn), chromium (Cr), and silver (Ag). The method for producing heat-resistant silica gel according to item (20).