JPH05139720A - Production for inorganic layer porous body - Google Patents

Abstract

PURPOSE:To continuously scrupulously and easily control pore diameter of an inorganic layer porous body by controlling the size of a multinuclear metal cation introduced as a pillar between layers of a swellable clay mineral to make distance between layers variable. CONSTITUTION:Hydrochloric acid is added into a solution containing zirconium ion. The solution obtained is heated at a temp. between room temp. and b.p. of the solution to form a multinuclear zirconium cation. The multinuclear zirconium cation is introduced between the layers of the clay mineral with ion exchanging by mixing the solution, in which the multinuclear zirconium cation is formed, with the swellable clay mineral. The swellable clay mineral is separated from the mixed solution obtained and is dried. Size of the multinuclear zirconium cation is easily changed by controlling ion conc. of zirconium, conc. of coexisting hydrochloric acid, heating temp. and heating time to change distance between the layers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an inorganic layered porous material used as an adsorbent, a catalyst, a carrier and the like.
More specifically, it relates to a method for producing an inorganic layered porous body in which a zirconium polynuclear cation or a zirconium oxide is introduced between layers of a swelling clay mineral to form a pore structure.

[0002]

2. Description of the Related Art Zeolite, which is well known as an inorganic porous material having a uniform pore size, is used as a catalyst, a carrier, an adsorption / separation material and the like. However, since the size of the pores of zeolite is limited and its use is limited, bulky polynuclear metal cations are introduced between the layers of the inorganic layered structural material, and after the introduction as necessary, they are heated and dehydrated to form oxides. Inorganic layered porous materials having larger pores have been synthesized.
As the inorganic layered structure material, the inorganic layered silicate smectite group clay mineral was first used. Later, artificial fluoromica and rectolite were used as new inorganic layered silicates, and zirconium phosphate, hydrotalcite, etc. were used as inorganic layered substances other than silicates. As large polynuclear metal cations to be introduced between layers, polynuclear cations such as aluminum, zirconium, titanium and iron have been studied (for example, Japanese Examined Patent Publication Nos. 62-20130 and 63).
28842). Also disclosed is an inorganic layered porous body in which colloidal particles of an inorganic oxide such as alumina, silica, and titania are introduced between layers of a smectite type mineral (for example, JP-B-62-41167 and JP-A-63-97773).

The polynuclear metal cation introduced between the clay layers is dehydrated by heat treatment while retaining its shape to form oxide fine particles, and becomes a porous body having high thermal stability. The polynuclear metal cations or oxide particles introduced between the clay layers play a role of supporting pillars by spreading and supporting the clay layer and are called pillars. Such an inorganic layered porous body has a uniform pore size and exhibits a shape-selective function similar to that of zeolite. When the inorganic layered porous material is used for such applications as shape-selective catalysts, adsorbents, or separation materials that serve as molecular sieves by utilizing these pores, the pore diameter should be strictly determined according to the size of the target molecule. Need to control.

The pore size of the inorganic layered porous material is represented by both the interlayer distance and the distance between pillars. Conventionally, the pore size has been controlled by adjusting the type of clay, the type of pillars introduced between clay layers, and the amount of introduction. If the amount of these pillars introduced increases, the distance between the pillars will decrease, and in the opposite case, the distance will increase. The amount of the pillars introduced is determined by the magnitude of the negative charge of the clay layer and the positive charge of the pillars, and the amount of the pillars increases when the clay layer has a large negative charge or the pillars have a small positive charge.

[0005]

However, the types of clay and pillars are limited, which makes it difficult to make the amount of pillars introduced variable and it is not possible to continuously and finely control the pore size. Therefore, when the inorganic layered porous material is used as a shape-selective substance, particularly when it is used as a molecular sieve, there is a problem that the selectable molecules are limited and the shape selection function is poor.

The object of the present invention is to control the size of polynuclear metal cations introduced as pillars between the layers of a swelling clay mineral, thereby making the interlayer distance variable so that the pore diameter of the inorganic layered porous material can be continuously changed. An object of the present invention is to provide a method for producing an inorganic layered porous body which can be finely and easily controlled.

[0007]

[Means for Solving the Problems] The present inventors have found that when hydrochloric acid is added to an aqueous solution containing zirconium ions and heat-treated, the ion concentration of zirconium at this time, the concentration of coexisting hydrochloric acid, the heating temperature, and the heating time. Accordingly, the inventors have found that the degree of hydrolysis of the zirconium salt, that is, the degree of polymerization of the zirconium cation can be easily controlled, and bulky zirconium polynuclear cations having different sizes can be synthesized, and arrived at the present invention.

In order to achieve the above object, the method for producing an inorganic layered porous body of the present invention comprises the step of adding hydrochloric acid to an aqueous solution containing zirconium ions; the aqueous solution containing the hydrochloric acid from room temperature to the boiling point of the aqueous solution. A zirconium polynuclear cation is generated by heating at a temperature between the two; an aqueous solution in which the zirconium polynuclear cation is generated and a swelling clay mineral are mixed, and the zirconium polynuclear cation is introduced between the layers of the clay mineral by ion exchange. And a step of separating the clay mineral from the mixed solution and drying.

The present invention will be described in detail below. A natural or artificial swelling clay mineral is used as the base material of the inorganic layered porous body of the present invention. These clay minerals are cation-exchangeable silicate clay minerals having a layered structure. Clay minerals of the smectite group, such as montmorillonite, beidellite, hectorite, saponite, nontronite, and the like, as well as clays containing these as the main components, such as acid clay and bentonite, can be used. It also includes swellable fluoromica minerals that are artificial compounds and their homomorphic substitution products. These swelling clay minerals may be used alone or in combination of two or more.

Cations such as sodium ions and calcium ions are coordinated between the layers of these clay minerals so as to compensate for the negative charges of the silicate layer. The bond strength between the interlayer cation and the silicate layer is relatively weak and has a property of easily exchanging with other cations (ion exchange property).
By utilizing the ion exchangeability of this swelling clay mineral and substituting the exchangeable cations between the layers with another large bulky cation, a porous body in which the layers are spread can be obtained. That is, the bulky cation becomes a pillar that supports the silicate layer of the swelling clay as described above. Intercalation is the insertion of another substance between the layers of the layered substance, and the product is called an intercalation compound or an intercalation compound. In the case of a porous body with an intercalation compound,
As described above, the pore diameter in the direction perpendicular to the layer (interlayer distance) is determined by the size of the pillar, and the pore diameter in the horizontal direction is determined by the distance between the pillars. Therefore, when synthesizing the inorganic layered porous body, adjustment of cations serving as pillars, quantitative or charge balance between the swelling clay mineral and cations are important factors. Especially, the size and uniformity of the pillars are important.

In the present invention, first, an aqueous solution containing zirconium ions is prepared. This aqueous solution is prepared by dissolving a soluble zirconium salt in water. An example of this zirconium salt is ZrCl ₄ , Zr (SO ₄ ) ₂ , Z
r (NO ₃ ) ₄ , ZrOCl ₂ , ZrOSO ₄ , ZrO (N
In addition to inorganic salts such as O ₃ ) ₂ , organic salts such as ZrO (CH ₃ COO) _{2 and the} like can be mentioned. ZrOCl ₂ is preferable from the viewpoint of solubility, stability or cost. Generally, in an aqueous solution of a zirconium salt, a polynuclear cation (hydroxy cation polymer) in which a plurality of metal ions are linked via a hydroxyl group and a hydrogen ion are generated by hydrolysis as shown in the following formula 1. Coordinated water is omitted in Formula 1. xZr ⁴⁺ ＋ yH ₂ O → [Zr _x (OH) _y ] ^{(4x-y) +} ＋ yH ⁺ (1) In this aqueous solution at room temperature x = 4 tetrameric hydroxy cation [Zr ₄ (OH) _16-n (H ₂ O) _{n + 8} ] ^{n +} is known to exist (Muha, Vaughan; J. Chem. Phys. 33 (1)
194-199 (1960)). Then, when this aqueous solution is heated, the reaction of the formula 1 proceeds further to the right, the value of x increases, and finally it precipitates as an insoluble metal hydroxide. That is, it is known that the aqueous solution undergoes hydrolysis by heating. The zirconium ion concentration in this aqueous solution is determined depending on the type of zirconium salt, the concentration of hydrochloric acid described below, the heating conditions of the solution containing hydrochloric acid, the amount of clay mineral added, etc. A range of 0.0 molar concentration (hereinafter referred to as M) is preferable.

Next, hydrochloric acid is added to an aqueous solution containing zirconium ions and heated. When hydrochloric acid is allowed to coexist during the hydrolysis of this aqueous solution, zirconium polynuclear cations having different degrees of polymerization can be obtained by controlling the ion concentration of zirconium, the concentration of coexisting hydrochloric acid, the heating temperature and the heating time. In particular, ZrOCl ₂ aqueous solution is hydrolyzed to HCl
The amount of HCl produced also affects the polymerization of the zirconium polynuclear cation. Therefore, the coexisting hydrochloric acid concentration means the concentration of all hydrochloric acid existing in the solution containing this HCl when HCl is produced by hydrolysis in addition to the added hydrochloric acid. Heating is performed in the temperature range from room temperature to the boiling point of the aqueous solution.

The degree of polymerization of the zirconium polynuclear cation produced when the heating temperature, the heating time and the hydrochloric acid concentration during the hydrolysis of the above aqueous solution are changed, that is, the size of the polynuclear cation will be described. The size of this polynuclear cation is
It is considered that when the zirconium polynuclear cation is introduced into the layer of the clay mineral by mixing the solution containing the zirconium polynuclear cation with the above-mentioned swelling clay mineral and performing ion exchange, it corresponds to the spread amount of the layer interval. Therefore, the sizes of polynuclear cations described below are estimated from the interlayer distance. In the vicinity of room temperature without special heating, the rate of hydrolysis of zirconium ions is very slow, and if the hydrochloric acid concentration is 3.0 M or less, zirconium polynuclear cations corresponding to an interlayer distance of 6 to 8 angstroms do not depend on the zirconium ion concentration. can get. When the hydrochloric acid concentration exceeds 3.0 M, when the swelling clay is mixed with this aqueous solution, the layer structure of the swelling clay is easily destroyed by the attack of the acid on the swelling clay.

When heating at a temperature above room temperature to the boiling point of the aqueous solution, the following can generally be said. When the concentration of hydrochloric acid is low, the first heated hydrolysis produces polynuclear cations corresponding to an interlayer distance of 6 to 8 angstroms. Then, when the hydrolysis proceeds while further heating, polynuclear cations having an interlayer distance of 13 to 16 Å are obtained. When the concentration of hydrochloric acid is medium, the first heated hydrolysis produces polynuclear cations corresponding to an interlayer distance of 13 to 16 angstroms. The polynuclear cation corresponding to 13 to 16 angstroms is a stable cation having the highest degree of polymerization, and thus a larger polynuclear cation cannot be obtained even if heating is continued. When the concentration of hydrochloric acid is high, the first heated hydrolysis produces polynuclear cations corresponding to an interlayer distance of 9-12 angstroms. Then, when the hydrolysis proceeds while further heating, polynuclear cations having an interlayer distance of 13 to 16 Å are obtained. In an aqueous solution in which a zirconium salt, which produces HCl by hydrolysis, such as ZrOCl ₂ , is dissolved, the amount of HCl produced varies depending on the ion concentration of zirconium and the temperature or time during hydrolysis. It is necessary to determine the concentration of hydrochloric acid to be added in consideration of heating temperature or heating time. In the present invention, when the zirconium polynuclear cation is generated, the concentration of hydrochloric acid is 0.001 to
It is preferably 3.0M.

The hydrolysis of the ZrOCl ₂ salt in the presence of hydrochloric acid will be specifically described below. (a) When the ZrOCl ₂ solution concentration is 0.1 M system: (1) When the added hydrochloric acid is less than 0.5 M, a polynuclear cation corresponding to an interlayer distance of 6 to 8 angstrom is generated by the first hydrolysis by heating. .. Further progress of hydrolysis while heating further produces polynuclear cations having an interlayer distance of 13 to 16 angstroms. (2) When the added hydrochloric acid is 0.5 M or more and less than 1.0 M, a polynuclear cation having an interlayer distance of 13 to 16 angstrom is produced by the first heated hydrolysis. (3) When the added hydrochloric acid is 1.0 M or more and 3.0 M or less, the first heated hydrolysis produces polynuclear cations having an interlayer distance of 9 to 12 Å. Further progress of hydrolysis while heating further produces polynuclear cations having an interlayer distance of 13 to 16 angstroms.

(B) When the ZrOCl ₂ solution concentration is 0.5 M system: (1) When the added hydrochloric acid is less than 0.5 M, a polynuclear cation corresponding to an interlayer distance of 13 to 16 angstroms by the first hydrolysis by heating. Is generated. (2) When the added hydrochloric acid is 0.5 M or more and 3.0 M or less, a polynuclear cation having an interlayer distance of 9 to 12 angstrom is produced by the first heated hydrolysis. Further progress of hydrolysis while heating further produces polynuclear cations having an interlayer distance of 13 to 16 angstroms. (c) When the ZrOCl ₂ solution concentration is 1.0 M system: (1) When the added hydrochloric acid is 0.5 M or more and 3.0 M or less, a polynuclear cation having an interlayer distance of 9 to 12 Å by the first heating hydrolysis. Is generated. Further progress of hydrolysis while heating further produces polynuclear cations having an interlayer distance of 13 to 16 angstroms.

This zirconium polynuclear cation aqueous solution is mixed with the aforementioned swelling clay mineral to prepare a suspension. By mixing, the exchangeable cation coordinated between the layers of the swelling clay mineral and the zirconium polynuclear cation undergo ion exchange. It is desirable to sufficiently stir this mixture with a stirrer or the like. As a mixing method, the swelling clay may be added while stirring the polynuclear cation aqueous solution, or the swelling clay may be dispersed in water and the polynuclear cation aqueous solution may be added thereto. The ion exchange can be carried out while maintaining the mixed solution at around room temperature, but it may also be carried out by heating the mixed solution from room temperature to the temperature of its boiling point. For example, the polynuclear cation aqueous solution may be mixed with the swelling clay while heating. The mixing ratio of zirconium and clay depends on the ion exchange capacity (CEC) of the swelling clay used, but 0.1 to 5.0 mol of zirconium is suitable for 100 g of clay.
When the amount of zirconium is less than 0.1 mol, the swelling clay layer does not spread sufficiently due to insufficient pillars to form a porous body, and when it is more than 5.0 mol, the polynuclear cation is CE.
Too much for C, which is uneconomical. By this ion exchange treatment, the interlayer spacing (pore diameter) of the swelling clay is expanded according to the size of the polynuclear cation to synthesize a porous body. The zirconium polynuclear cation preparation conditions are determined according to the desired interlayer distance (pore diameter) of the layered porous body.

After the ion exchange treatment, the solid portion is separated from the mixed solution, that is, the suspension by filtration, centrifugation, or the like, preferably, further, the ions adhering to the surface of the solid portion are removed by washing with water, and then the atmospheric pressure is applied. If it is dried at room temperature to 200 ° C. below, an inorganic layered porous body having a desired pore size can be obtained. When the dried inorganic layered porous body is further heat-treated at 200 to 800 ° C. under atmospheric pressure, the zirconium polynuclear cation acting as a pillar between the layers is dehydrated to form zirconium oxide. Although the pillars contract slightly due to dehydration, the crosslinked structure is maintained and an inorganic layered porous body having excellent heat resistance can be obtained.

[0019]

The zirconium polynuclear cation introduced as a pillar between the layers of the swelling clay mineral is produced by adding hydrochloric acid to an aqueous solution containing zirconium ions and heating the mixture. The size of the zirconium polynuclear cation is easily controlled according to the zirconium ion concentration, the concentration of coexisting hydrochloric acid, the heating temperature or the heating time. The pore size of the inorganic layered porous body, that is, the pore size in the direction perpendicular to the layer (interlayer distance) is set to a desired value according to the size of the zirconium polynuclear cation.

[0020]

As described above, according to the conventional method in which the pore diameter is controlled by changing the distance between the pillars, it is difficult to change the amount of introduction of the pillars, and therefore the pore diameter is finely controlled. I couldn't. On the other hand, according to the present invention, since the interlayer distance can be easily changed by controlling the size of the zirconium polynuclear cation introduced between the layers of the swelling clay mineral, the same kind of clay mineral can be used as the base material. Also, the pore diameter of the inorganic layered porous material can be set to a desired value depending on the size of the zirconium polynuclear cation. When the desired pore size is obtained, the inorganic layered porous material can be effectively used as a shape-selective substance, and can be effectively used for molecular sieves, shape-selective catalysts, and adsorbents. Produce an effect.

[0021]

EXAMPLES Next, the present invention will be described based on Examples in order to show specific embodiments of the present invention. The examples described below do not limit the technical scope of the present invention.

Example 1 1000 mL of a zirconium ion concentration of 0.1 M and HCl concentration of 0.1 M was prepared using zirconium oxychloride ZrOCl ₂ .8H ₂ O (special grade reagent) and 12N HCl (special grade reagent). did. The solution was then heated at 50 ° C. for 1 hour. After heating
Sodium montmorillonite at room temperature (Kunimine Industries Co., Ltd.)
Manufactured by Kunipia-F) 30.0 g and added with a stirrer 2
Stir well for 4 hours. Next, the montmorillonite was separated by centrifugation and further washed with distilled water until chlorine ions were not observed in the washing liquid. After that, the separated mormorillonite was dried under atmospheric pressure at 100 ° C. for 24 hours to obtain an inorganic layered porous body having a zirconium polynuclear cation introduced between layers.

<Example 2> The HCl concentration of the solution was adjusted to 0.5M.
Example 1 except that the heating of the solution was changed to 100 ° C. for 5 hours and the mixture was heated to reflux for 1 hour at 100 ° C. instead of stirring.
An inorganic layered porous body was obtained in the same manner as in. <Example 3> A part of the inorganic layered porous body obtained in Example 2 was heat-treated in an electric muffle furnace at 500 ° C for 2 hours to make zirconium oxide a zirconium polynuclear cation between the layers.

Example 4 1000 mL of a solution of zirconium ion concentration of 0.1 M and HCl concentration of 1.0 M was prepared using zirconium oxychloride ZrOCl ₂ .8H ₂ O (special grade reagent) and 12 N HCl (special grade reagent). did. The solution was then heated at 100 ° C. for 5 hours. After heating, it was added at room temperature sodium tetrasilicic fluorine mica that is a kind of artificial mica _{(NaMg 2. 5 Si 4 O 10} F 2) 10% sol (manufactured by Topy Industries (Ltd.)) 300 g, 24 hours sufficient stirrer And stirred. Next, sodium tetrasilicon fluoride mica was separated by centrifugation, and further washed with distilled water until chlorine ions were not observed in the washing liquid. After that, the separated mormorillonite was dried under atmospheric pressure at 100 ° C. for 24 hours to obtain an inorganic layered porous body having a zirconium polynuclear cation introduced between layers. <Example 5> A part of the inorganic layered porous body obtained in Example 4 was heat-treated at 500 ° C for 2 hours in an electric muffle furnace to obtain zirconium oxide as the zirconium polynuclear cation between the layers.

Example 6 An inorganic layered porous body was obtained in the same manner as in Example 4 except that the zirconium ion concentration of the solution was changed to 0.5M and the HCl concentration was changed to 0.1M. <Example 7> Part of the inorganic layered porous body obtained in Example 6 was heat-treated at 500 ° C for 2 hours in an electric muffle furnace to obtain zirconium oxide as an interlayer zirconium polynuclear cation.

<Example 8> The zirconium ion concentration of the solution was changed to 1.0 M, and the HCl concentration was changed to 0.5 M.
An inorganic layered porous body was obtained in the same manner as in Example 6 except that the mixture was heated under reflux at 100 ° C. for 1 hour instead of stirring. <Example 9> Part of the inorganic layered porous body obtained in Example 8 was heat-treated at 500 ° C for 2 hours in an electric muffle furnace to obtain zirconium oxide as the zirconium polynuclear cation between the layers.

<Measurement Items and Results> The interlayer distance, specific surface area and pore volume of the inorganic layered porous bodies obtained in Examples 1 to 9 were measured. The results are shown in Table 1. Regarding the interlayer distance, the bottom surface spacing value measured by X-ray diffraction
It was determined by subtracting the thickness of the silicate layer of 9.6 Å from (d ₀₀₁ ). The specific surface area was calculated by the BET method in the nitrogen adsorption method, and the pore volume was calculated by the CI method in the nitrogen adsorption method. (Hereafter, margins on this page)

[0028]

[Table 1]

As is clear from Table 1, when sodium montmorillonite was used as the swelling clay mineral in Examples 1 to 3, the ion concentration of zirconium was 0.1.
In the M-based Example 1, if the added HCl concentration was less than 0.5 M, a porous body corresponding to an interlayer distance of 6 to 8 Å was produced by the heated hydrolysis. But,
The HCl concentration was increased from that of Example 1 to 0.5M.
In Example 2 in which the amount was less than 1.0 M and the hydrolysis was performed by heating, the interlayer distance was doubled (corresponding to 13 to 16 Å), and the pore volume was correspondingly increased. In the case where sodium tetrasilicon fluoride mica is used as the swelling clay mineral in Examples 4 to 9 and the ion concentration of zirconium is 0.1 M in Example 4, the added HCl concentration is 1.0 M or more and 3. At a high concentration of 0 M or less, a porous body corresponding to an interlayer distance of 9 to 12 angstrom was produced by heating hydrolysis. In Example 6 in which the ion concentration of zirconium is 0.5 M, if the added HCl concentration is 0.1 M or more and less than 0.5 M, a porous body corresponding to an interlayer distance of 13 to 16 angstroms is produced by heating hydrolysis. Was done. In Example 8 in which the ion concentration of zirconium was 1.0 M, the added HCl was added.
When the concentration was a high concentration of 0.5 M or more and 3.0 M or less, a porous body corresponding to an interlayer distance of 9 to 12 angstroms was produced by heating hydrolysis. Further, heat treatment was performed after drying. Example 3, Example 5, Example 7 and Example 9
It was found that the porous body was dehydrated and the interlayer distance and the like were slightly reduced, as compared with Examples 2, 4, 6, and 8 in which the heat treatment was not performed.

Claims (5)

[Claims] 1. A step of adding hydrochloric acid to an aqueous solution containing zirconium ions, and a step of heating the aqueous solution containing the hydrochloric acid at a temperature between room temperature and the boiling point of the aqueous solution to produce zirconium polynuclear cations. A step of mixing an aqueous solution in which a zirconium polynuclear cation is generated and a swelling clay mineral and introducing the zirconium polynuclear cation by ion exchange between layers of the clay mineral; and a step of separating the clay mineral from the mixed liquid and drying A method for producing an inorganic layered porous body containing and. 2. The method for producing an inorganic layered porous body according to claim 1, wherein the zirconium ion concentration of the aqueous solution when hydrochloric acid is added is 0.01 to 5.0M. 3. The concentration of hydrochloric acid when the zirconium polynuclear cation is produced is 0.001 to 3.0M.
A method for producing the inorganic layered porous body described. 4. The method for producing an inorganic layered porous body according to claim 1, wherein the mixing is performed at a temperature between room temperature and the boiling point of the aqueous solution. 5. A swelling clay mineral is added to the swelling clay mineral after the drying step.
2. A step of heat-treating at a temperature of 0 to 800 ° C. to convert zirconium polynuclear cations to zirconium oxide.
A method for producing the inorganic layered porous body described.