JPH04254408A - Clay cross-linked porous body and production thereof - Google Patents

Abstract

PURPOSE:To obtain combined provision of catalyst function with simple process by metallic particulates in addition to shape selective function with uniform fine pore structure against the clay cross-linked porous body forming fine pore part in layer space of the smectite type clay minerals by cross-linking with inorganic compounds. CONSTITUTION:After addition and mixing of the clay cross-linked porous body into metal salt solution, metal ion in metal salt solution in this suspended solution is adsorbed on to fine pore part and surface part, and hydrolysis of this metal salt solution is executed if needed and after depositing a part of this hydrolysis products or whole part on to fine pore part and surface part of the above-mentioned porous body, reducing treatment is executed and disperse and metallic particulates are supported uniformly by fine pore part and surface part of the porous body.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clay crosslinked porous material suitable for use as a catalyst, an adsorbent/separator, a deodorizing material, etc., and a method for producing the same. More specifically, the present invention relates to a clay crosslinked porous body that supports metal fine particles in its pores and surface and has a shape-selective function due to a uniform pore structure, as well as a catalytic function due to the metal fine particles, and a method for producing the same. be.

0002

BACKGROUND OF THE INVENTION Zeolite and clay crosslinked porous materials have been known as inorganic porous materials containing uniform micropores. The clay crosslinked porous body is an interlayer compound having a structure in which layers of layered clay minerals such as smectite are crosslinked with inorganic oxide fine particles such as Al2O3 and ZrO2, and includes slit-like pores. For this reason, inorganic oxide fine particles are called pillars. The pore diameter of this porous body, that is, the interlayer distance, is controlled by the type and size of the pillars inserted between the layers, and is in the range of several angstroms to several tens of angstroms. Since the clay crosslinked porous material has a uniform pore diameter that is about the same as the molecular diameter, it has a shape-selective function as a molecular sieve similar to zeolite.

[0003] Furthermore, since clay crosslinked porous materials are generally solid acids and exhibit catalytic activity, their use as catalysts for selectively synthesizing only desired products from among various products is being considered. For example, it has been described in several documents that it is effective as a cracking catalyst in petrochemistry (E. Kikuchi, T. Matsuda;
tal. Today, 2, 297 (1988),
M. L. Occeli, R. J. Rennard;
Catal. Today, 2, 309 (198
8), H. Ming-Yuan, L. Zhongh
ui, M. Enze; Catal. Today,
2, 321 (1988), M. L. Occeli;
Catal. Today, 2, 339 (198
8)).

However, even if it is attempted to use the clay crosslinked porous material as a catalyst, the range of use of the clay crosslinked porous material as it is is limited to solid acid catalysts. On the other hand, a metal particulate catalyst is known as a typical catalyst. Although metal fine particles do not have shape selectivity, they exhibit high activity in other catalytic functions that clay crosslinked porous materials do not have, such as hydrogenation, hydrogenolysis, dehydrogenation, oxidation, ammonia synthesis, and other reactions. However, the synthesis of these metal fine particles is laborious and costly, and the synthesized metal fine particles are extremely unstable, easily oxidized, and easily aggregated. Conventionally, in order to eliminate these drawbacks and increase the exposed area of metal fine particles to exhibit higher activity,
Metal particulate catalysts are generally prepared by mixing an inorganic support such as alumina with an aqueous metal salt solution and subjecting this mixture to a reduction treatment, and are used by being supported on the surface of the inorganic support.

[0005]

[Problem to be solved by the invention] However, since such metal fine particle catalysts do not have shape selectivity, if metal fine particles can be stably dispersed and supported in the pores or surface of the clay crosslinked porous material, shape selectivity can be improved. A new type of highly value-added clay crosslinked porous material that has the catalytic function of metal fine particles in addition to the functions can be obtained. However, until now, there has been no clay crosslinked porous material supporting such fine metal particles, nor has the manufacturing technology been established.

An object of the present invention is to provide a clay crosslinked porous material having a catalytic function in addition to a shape-selective function, and a method for producing the same.

[0007]

[Means for Solving the Problems] While conducting repeated research on the adsorption properties of clay crosslinked porous materials and changes in the state of adsorbed substances, the present inventors treated the clay crosslinked porous materials with an aqueous metal salt solution.
After adsorbing metal ions and metal hydroxides in the pores and surface area, if reduction treatment is performed, the metal ions and metal hydroxides become fine metal particles and are uniformly spread over the pores and surface area of the porous body. The present invention has been achieved based on the discovery that the present invention is carried out in a dispersed manner.

That is, the clay crosslinked porous body of the present invention is characterized in that fine metal particles are supported in the pores formed by crosslinking with an inorganic substance between layers of smectite clay minerals and on the surface thereof. In addition, the method for producing a clay crosslinked porous body of the present invention includes mixing a clay crosslinked porous body in which pores are formed between layers of clay minerals by crosslinking an inorganic substance with an aqueous metal salt solution, and introducing metal ions into the pores of the porous body. a step of adsorbing the metal salt to the pores and the surface, and if necessary, further hydrolyzing the metal salt aqueous solution and depositing part or all of the hydrolysis product in the pores and the surface of the porous body; This method includes a step of reducing the metal ions or hydrolysis products into metal fine particles.

The present invention will be explained in detail below. The clay crosslinked porous material that is the base material of the present invention is a smectite clay mineral, and between the layers are Al2O3, ZrO2, Cr2O3,
SiO2, TiO2, Fe2O3, Bi2O3
It is a type of intercalation compound in which inorganic oxide fine particles such as Smectite-type clay minerals are layered clay minerals with ion-exchange properties, including naturally occurring montrillonite, beidellite, hectorite, saponite, nontronite, chlorite, etc., as well as artificially synthesized swellable fluorinated mica and other minerals. Including isomorphic substitutions. The exchangeable cations such as Na+, Li+, and Ca+ present between the layers of these smectite clay minerals are replaced with other bulky inorganic polynuclear metal cations such as [Al13O4(OH)24(H2O)1
2]7+, [Zr4(OH)8(H2O)16]8+,
[Fe3(CH3COO)7(OH)(H2O)2]+
A layered porous material having a pore structure in which fine oxide particles are crosslinked between the layers can be obtained by ion exchange with the like and further heating and dehydration.

In the adsorption step, the clay crosslinked porous material having the pore structure formed therein is mixed with an aqueous metal salt solution, and metal ions are adsorbed into the pores and surface. Although it is essential that the metal salt used be soluble in water, any metal salt may be used as long as the metal ions contained therein become fine metal particles through the reduction treatment described below. Examples of metal ions of metal salts include Fe2+, Fe3+, Co2+, Ni2+, C
u2+, Zn2+, Cd2+, W6+, Ir3+, Pb
2+ etc. are mentioned. These metal ions may be used alone or in combination of two or more kinds. Further, the form of the metal salt may be, for example, an inorganic salt such as chloride, nitrate, sulfate, or perchlorate, or an organic acid salt such as acetate or formate, or a complex such as ammine complex. It may also be a compound. In addition, as an auxiliary agent to promote or stabilize the dissolution of metal salts, for example, acids such as hydrochloric acid, nitric acid, and sulfuric acid, alkalis such as sodium hydroxide and aqueous ammonia, or complexing agents such as amines may be coexisting. I don't mind if you let me.

[0011] The above-mentioned clay crosslinked porous material having a pore structure is added to and mixed with these metal salt aqueous solutions to prepare a suspension. At this time, in order to facilitate the adsorption of metal ions between the layers, it is desirable to dry the clay crosslinked porous material sufficiently in advance. The mixing ratio of the clay crosslinked porous material to the metal salt is appropriately determined from the range of 0.001 to 10 moles of the metal salt per 100 g of the clay crosslinked porous material depending on the amount of metal supported and the hydrolysis method described below. The amount of metal ions adsorbed by the clay crosslinked porous material in this adsorption step is about 0.1 to several percent. Furthermore, most of the metal ions are adsorbed in the pores, and only a small amount is adsorbed on the surface. In order to further increase the amount of metal supported, the following hydrolysis is performed.

In the hydrolysis step, the metal salt is hydrolyzed to deposit hydrolysis products such as metal hydroxides in the pores and surface. The method of this hydrolysis is not particularly limited as long as the hydrolysis product is formed as a precipitate. Preferred methods for hydrolyzing metal salts include: (1) adding a precipitant to a suspension in which a metal salt aqueous solution and a clay crosslinked porous material are mixed; (2) heating or pressurizing the suspension; (2) adding a precipitant to the suspension; Examples include a method of heating or pressurizing after adding a precipitant.

[0013] It is thought that the deposition of hydroxides and the like progresses using metal ions adsorbed in the pores as nuclei. The metal ions adsorbed in the pores are actually acoions [Me(H2O)x]n+ coordinated with water molecules, but these acoions undergo polarization between the silicate layers.
It has been reported that part of the coordinated water is dissociated as shown in the following formula (1) (S. Yamanaka and G.
．． W. Brindley; Clay and Cla
y Minerals 26, (1), 21-24
(1978)). [Me(H2O)x]n+ →
[Me(H2O)x-y(OH)y](ny)+
+ yH+ (1) In other words, the metal ions in the pores are in a more advanced state of hydrolysis than the metal ions in the solution, so when a precipitant is added or heated, hydroxide is released from the pores first. It is thought that it is easy to precipitate. For this reason,
The amount of hydroxide deposited on the surface is smaller than on the pores. The final form of the precipitate varies depending on the type of metal salt used and the hydrolysis method. Generally, there are many hydroxides, but
The metal salt may be partially hydroxylated as a basic salt, or the hydroxide may be further dehydrated to become an oxide.

When the metal salt aqueous solution is acidic, sodium hydroxide (
Alkaline solutions such as NaOH), sodium carbonate (Na2CO3) or ammonia (NH3) are commonly used. Conversely, when the aqueous metal salt solution is alkaline, acidic solutions such as hydrochloric acid, nitric acid, sulfuric acid, acetic acid, and formic acid are used. Depending on the amount of these precipitants added, the amount of hydroxide deposited in the pores and the surface changes, and the amount of metal supported is controlled. When adding a precipitant, it is desirable to drip the metal salt aqueous solution and the suspension of the clay crosslinked porous material gradually while sufficiently stirring the suspension to prevent precipitation from the liquid phase in areas other than the pores and surface areas as much as possible. .

Examples of the metal salt aqueous solution that is hydrolyzed by heating include thermally unstable organic metal salts such as acetates, ammine complexes, and chelate complexes. Ammine complexes and chelate complexes are also hydrolyzed by pressure. The amount of metal supported is mainly controlled by changing the heating temperature or heating time. The higher the heating temperature and the longer the heating time, the more the amount of metal supported increases.

[0016] Examples of compounds that generate a precipitant by heating or applying pressure after adding a precipitant include urea ((NH2)2CO), hexamethylenetetramine (
(CH2)6N4) and the like. When an aqueous solution of these compounds is heated, hydrolysis proceeds gradually as shown in the following formula (2) or (3), and ammonia is generated from the entire solution. (NH2)2CO + H2O
→ 2NH3 + CO2 (2
) (CH2)6N4 + 6H2O
→ 4NH3 + 6HCHO (
3) As a result, the entire solution becomes uniformly alkaline, and the metal salt is hydrolyzed to form a precipitate. In this case, the resulting precipitate contains basic salts in addition to hydroxides. The amount of metal supported is controlled by changing the amount of precipitant added, heating temperature, or heating time.

[0017] The suspension after the adsorption step or the hydrolysis step is
After removing the solution by means such as filtration or centrifugation and washing the solid portion with water, if necessary, drying at room temperature to 150°C. Furthermore, it may be heat-treated at a temperature of 150 to 800° C. to dehydrate metal ions or hydroxides in the pores and surface portions to form oxides.

In the reduction step, the clay crosslinked porous material on which metal ions or metal hydroxides have been deposited in the adsorption step or hydrolysis step is reduced in the liquid phase or gas phase to form metal fine particles. For reduction in a liquid phase, the clay crosslinked porous body on which metal ions or metal hydroxides have been deposited after washing with water is mixed with a reducing agent solution and further heated if necessary. Examples of the reducing agent include formalin, dimethylformamide, hydrazine, sodium hypophosphite, and sodium borohydride. At this time, various auxiliary agents may be added in order to stabilize the reducing agent, promote the reduction reaction, or adjust the pH. Reduction in the gas phase is carried out by heat-treating a dried or heat-treated clay crosslinked porous material on which metal ions or metal hydroxides have been deposited in a reducing gas such as hydrogen or carbon monoxide. Generally, a sample is placed in a reducing atmosphere furnace and heated while flowing reducing gas. Although the heating temperature depends on the type of metal ion to be reduced, it is generally 100 to 1500°C.

[0019] Also referred to as liquid phase reduction and gas phase reduction.
The reduction amount and particle size of the metal fine particles are controlled by the reduction time and reduction temperature. That is, if the reduction time is short or the reduction temperature is low, the amount of reduction to metal is small and the particle size thereof is also small. On the other hand, if the reduction time is long or the reduction temperature is high, the amount of reduction to metal will increase, and the metals will aggregate and the particle size will increase. Furthermore, as this aggregation progresses, the metal fine particles in the pores cannot stay within the narrow pores, and some of them begin to move to the surface. Therefore, as the reduction time becomes longer or the reduction temperature becomes higher, the amount of metal supported on the surface increases.

[0020]

[Effects of the Invention] As described above, according to the present invention, a clay crosslinked porous material is treated with an aqueous metal salt solution to adsorb metal ions and metal hydroxides into the pores and surface of the porous material. After that, by a simple process of reduction treatment, metal fine particles can be uniformly dispersed and supported in the pores and the surface. As a result, a novel clay crosslinked porous body is obtained which has not only the shape selectivity function due to the uniform pore structure but also the catalytic function due to the metal fine particles.

[0021]

EXAMPLES Next, the present invention will be explained 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> 0.2M aluminum chloride (
While vigorously stirring 750 mL of an aqueous solution (AlCl3.6H2O) with a stirrer, 3750 mL of a 0.1M aqueous sodium hydroxide (NaOH) solution was added at a rate of about 50 mL per hour.
After dropping the mixture at a rate of mL, an aqueous Al polynuclear cation solution was prepared by refluxing at 95° C. for 2 hours. To this was added 30.0 g of dry powder of sodium montmorillonite (Kunimine Kogyo Co., Ltd., Kunipier F), and
Stir for days to remove Na ions between the montmorillonite layers.
Ion exchanged with polynuclear cations. The solid portion was separated by centrifugation, washed with distilled water until no chlorine ions were observed in the washing liquid, and further dried at 100°C. This dried product was heated in an electric muffle furnace under atmospheric pressure for 40 minutes.
Heat treatment was performed at 0°C for 2 hours to obtain an Al2O3-montmorillonite porous body (hereinafter referred to as Al-Mont). The interlayer distance of Al-Mont determined from X-ray diffraction was 8.4 angstroms.

0.0 g of this Al-Mont.
It was added to 200 mL of 1M nickel nitrate (Ni(NO3)2.6H2O) aqueous solution and stirred for 20 hours to adsorb Ni2+ ions to the pores and surface of Al-Mont. After removing unadsorbed nickel nitrate by centrifugation and water washing, the solid part was mixed with 200 mL of a reducing agent aqueous solution with the following composition, and the adsorbed Ni2+ ions were reduced to metallic nickel by stirring at 90°C for 2 hours. did. Sodium hypophosphite 30 g/L Sodium citrate 100 g/L Ammonium chloride 50 g/L
After the reduction treatment, the solid part was separated by centrifugation, washed with water, and dried under reduced pressure at 40°C in a vacuum dryer to obtain Al-Mont (hereinafter referred to as Ni-Al-M) carrying Ni fine particles.
ont) was obtained. The amount of Ni supported in this Ni-Al-Mont was 1.2% by weight. Further, when observed with a transmission electron microscope, it was confirmed that the Ni particles had a diameter of 10 to 40 angstroms and were uniformly supported.

A 10% sol of sodium tetrasilicon fluorine mica (NaMg2.5Si4O10F2) (manufactured by Topy Industries, Ltd.), which is a type of artificial mica, was dried at 100°C, and then ground to 88 μm or less to obtain a dry powder. Ta. 15.0 g of the above dry powder of sodium tetrasilicon fluorine mica was added to the Al polynuclear cation aqueous solution prepared in Example 1, and the mixture was stirred and suspended at room temperature for 5 days to convert the Na ions between the mica layers into Al polynuclear cations. Ion exchanged. Next, Example 1
Centrifugation, washing with water, drying, and heat treatment at 400°C were carried out in the same manner as in
(called SM). Al-TSM determined from X-ray diffraction
The interlayer distance was 8.8 angstroms.

[0025] 2.0g of this Al-TSM was 0.1M
Cobalt nitrate (Co(NO3)2.6H2O) aqueous solution 2
00 mL and stirred for 20 hours to adsorb Co2+ ions to the pores and surface of Al-TSM. Next, while vigorously stirring this suspension, 0.1M NaOH was added dropwise at a rate of about 10 mL per hour. Cobalt nitrate was hydrolyzed and cobalt hydroxide was deposited in the pores of Al-TSM. At this time, the amount of NaOH added to Al-TSM was 0.1, 0.2, 0 per 100g of Al-TSM.
．． The amount of cobalt hydroxide deposited in the pores was changed by changing the amount from 3 to 0.4 mol. After adding this NaOH, stirring was continued for another day, and then the solid portion was thoroughly washed with water and dried at 100°C. 1.0 g of each of these dried products was placed in a quartz test tube, and heated at 400°C in a hydrogen stream while supplying 100 mL of hydrogen per minute to an atmosphere firing furnace (MINIVAC-II, manufactured by Tokyo Vacuum Co., Ltd.).
Al-TS with different amounts of Co supported
M (hereinafter referred to as Co-Al-TSM-1 to 4) was obtained. The amounts of Co supported in these Co-Al-TSM-1 to 4 were 3.1, 5.3, 7.4, and 9.1% by weight, respectively. Furthermore, when observed with a transmission electron microscope,
It was confirmed that these Co particles had a diameter of 50 to 100 angstroms and were uniformly supported.

<Example 3> After refluxing 1 L of 0.4M zirconium oxychloride (ZrOCl2.8H2O) in a boiling state for 1 hour, 30.0 g of sodium tetrasilicon fluorine mica powder was added thereto, and the mixture was stirred with a stirrer. However, refluxing was continued in a boiling state for an additional 16 hours. Thereafter, in the same manner as when synthesizing Al-Mont in Example 1, washing with water,
After drying, heat treatment was performed at 500°C for 2 hours to form ZrO2
- An artificial mica porous material (hereinafter referred to as Zr-TSM) was obtained. The interlayer distance of Zr-TSM determined from X-ray diffraction is 12.
It was 6 angstroms.

On the other hand, 1500 mL of 0.2M ammonia water
and 0.1M copper chloride (CuCl2.2H2O) aqueous solution 20
Mix 0 mL of copper-ammine complex ([Cu(NH3)
4] Cl2) aqueous solution was prepared. The above Zr was added to this aqueous solution.
-Add 5.0g of TSM and stir for 16 hours.
-Cu2+ ions were adsorbed on the pores and surface of TSM. Subsequently, the mixture was refluxed in a boiling state while stirring with a hot stirrer. The copper-ammine complex is hydrolyzed to form Zr-T
Copper oxide was deposited in the pores of the SM. At this time, the amount of copper oxide deposited in the pores was controlled by changing the heating time to 10, 30, 60, and 180 minutes. After heating,
The solid portion was thoroughly washed with water and dried at 100°C.

This dried material was subjected to hydrogen reduction treatment in the same manner as in Example 2, and Zr-TSM with different supported amounts of Cu (hereinafter referred to as Cu
-Zr-TSM-1 to 4) were obtained. However, the heating temperature was 250°C. The supported amounts of Cu in these Cu-Zr-TSM-1 to 4 were 5.0, 8.1, 10.6, and 12.
It was 1% by weight. Further, when observed using a transmission electron microscope, it was confirmed that these Cu particles had a diameter of 80 to 140 angstroms and were uniformly supported.

Claims (12)

[Claims] 1. A clay crosslinked porous body in which pores are formed between layers of smectite clay minerals by crosslinking with an inorganic substance, characterized in that fine metal particles are supported on the pores and surface of the porous body. Clay cross-linked porous material. [Claim 2] The inorganic substance is Al2O3, Zr02,
Cr2O3, Bi2O3, SiO2, TiO2,
The clay crosslinked porous material according to claim 1, which is one or more inorganic oxides selected from the group of Fe2O3. 3. A clay crosslinked porous material in which pores are formed between layers of smectite clay minerals by crosslinking with an inorganic substance is mixed with an aqueous metal salt solution, and metal ions are adsorbed into the pores and surface of the porous material. A method for producing a clay crosslinked porous body, comprising a step of reducing the metal ions to produce metal fine particles. 4. Claim 3, wherein the reduction treatment is performed by mixing a porous body adsorbing metal ions with a reducing agent solution.
The method for producing the clay crosslinked porous body described above. 5. The method for producing a clay crosslinked porous body according to claim 3, wherein the reduction treatment is performed by heating the porous body adsorbing metal ions in a reducing gas. 6. A clay crosslinked porous body in which pores are formed between layers of smectite clay minerals by crosslinking with an inorganic substance is mixed with an aqueous metal salt solution, and metal ions are adsorbed into the pores and surface of the porous body. a step of hydrolyzing the metal salt aqueous solution in the suspension in which the clay cross-linked porous body is suspended, and transferring part or all of the hydrolyzed product to the pores of the porous body to which the metal ions have been adsorbed; further depositing on the surface;
A method for producing a clay crosslinked porous body, comprising a step of reducing the hydrolysis product to produce metal fine particles. 7. The method for producing a clay crosslinked porous material according to claim 6, wherein the hydrolysis treatment is performed by adding a precipitant to the suspension. 8. The method for producing a clay crosslinked porous material according to claim 6, wherein the hydrolysis treatment is performed by heating or pressurizing the suspension. 9. The method for producing a clay crosslinked porous body according to claim 6, wherein the hydrolysis treatment is carried out by adding a precipitant to the suspension and then heating or pressurizing the suspension. 10. The method for producing a clay crosslinked porous body according to claim 6, wherein the hydrolysis product is one or more of metal hydroxides, basic salts, and oxides of an aqueous metal salt solution. 11. The method for producing a clay crosslinked porous material according to claim 6, wherein the reduction treatment is carried out by mixing the porous material in which the hydrolysis product is deposited in the pores and the surface with a reducing agent solution. 12. The method for producing a clay crosslinked porous body according to claim 6, wherein the reduction treatment is carried out by heating the porous body in which the hydrolysis product is deposited in the pores and the surface in a reducing gas. .