JPS6250407B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to novel microporous clay materials useful as catalyst supports, adsorbents, and thermal insulators.

More specifically, this invention relates to a novel microporous clay material in which a neutral water-soluble polymer compound and an inorganic substance are interposed between layers of smectite minerals, and the interlayer spacing is maintained at 20 angstroms or more.

Smectite-type minerals include montmorillonite, bentonite, chlorite, hydelite, hectorite, and synthetic mica. For example, in the crystal structure of montmorillonite, a silicate tetrahedral layer, an alumina octahedral layer, and a silicate tetrahedral layer are stacked and bonded to form a single crystal layer. In addition, aluminum, the central metal of the octahedral layer, is partially replaced by magnesium, which has a lower positive charge, which gives the layer a negative charge. Alkali metal ions (mainly Na ⁺ ) corresponding to this negative charge are interposed between the layers to neutralize the charge on the crystal layer. Therefore, montmorillonite has a large cation exchange capacity. Also, due to the hydration properties of the exchangeable cations, a significant amount of water is absorbed between the layers, resulting in extremely high swelling properties. Other smectite-type minerals have similar properties to montmorillonite, and all of these minerals are used as catalyst carriers and adsorbents by taking advantage of their layered structures.

Conventional porous clay materials, such as JP-A-54-5884
No. 54-16386 discloses a material containing cationic hydroxy metal complexes, aluminum chlorohydroxide complexes, silicates, phosphates, zirconia, etc. between the layers of a smectite mineral, and the interlayer spacing is approx. 10 angstroms or less.

However, when a smectite mineral with a short interlayer distance as described above is used as a heat insulating material, a sufficient effect may not be obtained. For example, when this material is used to make insulation materials, the layers become clogged with water even at a relative humidity of about 10%. Therefore, a sufficient heat insulation effect cannot be achieved.

In view of the above circumstances, this invention was developed mainly as a result of intensive research aimed at producing a microporous clay material made of smectite minerals with a relatively long interlayer distance.
A microporous clay material with a pore diameter of 20 angstroms or more has been discovered. A cross-sectional view of the structure of the microporous clay material of this invention is shown in FIG. a is a crystalline layer of smectite-type minerals,
Its thickness d ₁ is approximately 10 angstroms. Spirals and b are water-soluble polymers and inorganic substances inserted between the layers, and serve as pillars that support the interlayers. and
An interlayer spacing of _d2 appears. The microporous clay material of this invention has a d ₂ of 20 angstroms or more.

The smectite type mineral in this invention can be selected from, for example, montmorillonite, bentonite, chlorite, beidellite, hectorite, synthetic mica and substituted analogs thereof, or a mixture of two or more thereof.

Further, as the water-soluble synthetic polymer compound, a neutral water-soluble polymer compound such as polyethylene oxide or polyvinyl alcohol, which has a neutral charge when dissolved in water, is used.

Inorganic substances are gelled products of silica sol reacted with cations or aluminate ions, and these cations include calcium, barium, magnesium,
Ions of divalent or higher valent metals such as aluminum, iron, nickel, cobalt, and lanthanides are used.

As a result of examining the interlayer spacing of the microporous clay of the present invention using the nitrogen adsorption method, the results showed that the interlayer spacing of the microporous clay of the present invention was mainly 20% as shown in Figure 2.
The interlayer spacing is not less than angstroms and not more than 60 angstroms. Furthermore, the surface area with an interlayer spacing of 20 angstroms or more is approximately 260 m ² /g, the total surface area is approximately 430 m ² /g, and the nitrogen capacity is approximately 0.4
ml/g, specific volume is approximately 0.8 cm ³ /g, and porosity is approximately 0.5.

Figure 3 shows the state when a smectite mineral is mixed with water, where a is the crystal layer and d ₁ is the thickness of the crystal layer (approximately 10 angstroms). The distance d ₃ changes depending on the mixing ratio of smectite minerals and water, and can take a maximum value of about 500 angstroms if a large amount of water is present. However, smectite minerals
When mixed with water containing cations such as Ca ²⁺ and Al ³⁺ , the positive charge between the layers increases and d ₃ decreases. And if the amount of cations increases, d ₃ will finally be about
It becomes 10 angstroms.

In conventional production methods, for example, JP-A-54-5884 and JP-A-54-16386, smectite minerals are mixed with water and cationic inorganic substances, and the cationic inorganic substances are ion-exchanged with exchangeable cations between the layers. Since the manufacturing method involves subsequent hydrolysis, the interlayer distance of the product is less than about 10 angstroms.

However, when using smectite minerals with short interlayer distances as mentioned above as heat insulating materials, sufficient effects may not be obtained, as explained above in the section on "microporous clay."

The microporous clay material of this invention is produced by adding silica sol, a water-soluble synthetic polymer compound, a cation co-supplementing substance or aluminate ion, and water to a smectite mineral, thoroughly mixing the mixture, and then drying the mixture. can do.

The smectite type mineral in this invention can be selected from, for example, montmorillonite, bentonite, chlorite, beidellite, hectorite, synthetic mica and substituted analogs thereof, or a mixture of two or more thereof. The water-soluble synthetic polymer compound used in the production is a neutral water-soluble polymer compound obtained by synthesis of polyethylene oxide, polyvinyl alcohol, etc., which have a neutral charge when dissolved in water.

Moreover, as the silica sol, one containing one or more types of anions such as polymer silica and silicate ions, and which reacts with cations to form a gel is used. As the cation, ions of divalent or higher valent metals such as calcium, barium, magnesium, aluminum, iron, nickel, cobalt, and lanthanide are used.

In the production of this invention, first, a smectite mineral, water, a water-soluble synthetic polymer compound, and an inorganic substance are mixed. The amount of water should be 0.4 ml or more per gram of smectite mineral. Further, the concentration of the aqueous solution of the water-soluble synthetic polymer compound is set within a range that exhibits fluidity at a viscosity below the level where the solution slightly flows when tilted. Inorganic substances are 0.05g to 1g per 1g of smectite minerals.
If it is less than 0.05 g, it will not form a pillar large enough to widen the interlayer gap, and if it is more than 1 g, it is disadvantageous to use it because the porosity will decrease. The mixing order is that a mixed aqueous solution of a water-soluble synthetic polymer compound and an inorganic substance is mixed with a smectite mineral. Alternatively, any method may be used in which an inorganic substance is mixed into a mixture of a smectite mineral and an aqueous solution of a water-soluble polymer compound. After mixing as above, cations are added. The amount of cations is in the range of 1 x 10 ^-4 mol to 1 x 10 ^-2 mol per 1 g of smectite mineral; below 1 x 10 ^-4 mol, the inorganic substance will not gel sufficiently, and above 1 x 10 ^-2 mol It is disadvantageous to use it for reasons such as a decrease in porosity. Furthermore, aluminate ions may be added in addition to cations. The addition amount should be equivalent to the inorganic substance.

The state after mixing is shown in FIG. Here, C is a gel produced by a reaction between an inorganic substance and a cation or an aluminate ion. Gel generation will be explained in detail. The inorganic substance in this invention is polymeric silica (silica sol), which is a colloidal form of negatively charged amorphous silica particles dispersed in water, and the particles have a spherical shape. -SiOH groups and -OH ^- ions exist on the surface of the particles, and an electric double layer is formed by the alkali ions added as a stabilizer, which is stabilized by repulsion between the particles. When this charge balance is improved by adding cations, etc., thickening, gelation, aggregation, etc. occur. The degree of gelation varies depending on the type, concentration, temperature, etc. of the cations added. When a gel is dried, it changes from a water-containing gel to a dry gel. combination) A strong dry gel solid is obtained. The thermal changes in this dried gel were measured by differential thermal analysis and thermogravimetric analysis, and the results are as follows. At about 150°C, the water adsorbed on the silica gel dehydrates, resulting in a weight loss of about 5%.

Silanol dehydration occurs between 400°C and 700°C. No particle change is observed up to this temperature.

The spiral line in FIG. 4 represents a water-soluble synthetic polymer compound. In this state, the appearance of structural viscosity of the water-soluble synthetic polymer compound causes the interlayer to expand.
To explain this in more detail, in general, in an aqueous polymer solution, as the molecular weight of the polymer increases and the concentration increases, the viscosity increases and becomes difficult to flow. This is due to the appearance of structural viscosity due to the formation of a network structure resulting from the so-called "entanglement" phenomenon in which polymer threads become entangled. Then, it begins to exhibit rubber elasticity.

The present invention is characterized in that the characteristics of these water-soluble synthetic polymer compounds are applied to the interlayers of smectite minerals to prevent the interlayer distance from becoming small due to the insertion of inorganic substances and cations.

By drying at room temperature or up to 200°C under the conditions shown in Figure 4, water between the layers is eliminated, the spread of the water-soluble synthetic polymer compound becomes smaller, and pillars of inorganic matter are formed between the layers (Figure 1). ).

Therefore, another feature of the present invention is that by fixing these water-soluble synthetic polymer compounds and inorganic substances between the layers of smectite minerals and then drying them, a microporous clay material of smectite minerals with long interlayer distances can be obtained. It's in the point where you can get it.

Furthermore, as a result of examining the product of this invention by a nitrogen adsorption method, as shown in FIG. 2, it is found that it is mainly a microporous clay material having an interlayer spacing of 20 angstroms or more. Furthermore, the surface area where the interlayer spacing is 20 angstroms or more is approximately 260 m ² /g at maximum, and the total surface area is approximately 430 m ² /g at maximum. Nitrogen capacity is up to approximately 0.4
ml/g, specific volume is up to about 0.8 cm ³ /g, and porosity is up to about 0.5.

These microporous clay materials, when oriented, are useful in high performance insulation materials.

Examples of this invention will be shown below.

Example 1 Polyethylene oxide with a degree of polymerization of 39,000 to 50,000
Dissolve 0.036g in 9ml of water. 31 in 9 ml of dissolved 0.4 weight percent polyethylene oxide aqueous solution.
Add 0.9 ml of a weight percent silica sol aqueous solution (SI-350, manufactured by Catalysts Kasei Kogyo), and stir and mix.
Sodium montmorillonite 1.00 into mixed aqueous solution
g and further stir and mix. To the mixture thus obtained was added 3 ml of a 3.2 weight percent AlCl ₃ .6H ₂ O aqueous solution, stirred and mixed, and then left to dry in a dryer at 50° C. for 2 days. As a result of investigating the pore size, surface area, nitrogen capacity, specific volume, and porosity of the product using the nitrogen adsorption/desorption method, the pore size at which the pore distribution peaks is 50 angstroms, and the surface area is 225 m for pore diameters of 20 angstroms or more. The total surface area was 372 ^{m 2 /} g, the nitrogen capacity was 0.29 ml/g, the specific volume was 0.69 cm ³ /g, and the porosity was 0.42.

Example 2 Polyethylene oxide with a degree of polymerization of 39,000 to 50,000
Dissolve 0.073g in 18ml of water. 31 in 18 ml of dissolved 0.4 weight percent polyethylene oxide aqueous solution
Add 1.8 ml of a weight percent silica sol aqueous solution (SI-350, manufactured by Catalysts Kasei Kogyo), and stir and mix.
Sodium montmorillonite 1.00 into mixed aqueous solution
g and further stir and mix. To the mixture thus obtained was added 3 ml of a 3.2 weight percent AlCl ₃ .6H ₂ O aqueous solution, stirred and mixed, and then left to dry in a dryer at 50° C. for 2 days. As a result of examining the pore size, surface area, nitrogen capacity, specific volume, and porosity of the product using the nitrogen adsorption/desorption method, the pore size at which the pore distribution peaks is 52 angstroms, and the surface area is 262 m for pore diameters of 20 angstroms or more. The total surface area was 428 ^{m 2 /} g, the nitrogen capacity was 0.36 ml/g, the specific volume was 0.76 cm ³ /g, and the porosity was 0.47.

[Brief explanation of the drawing]

FIG. 1 shows a cross-sectional view of the structure of the microporous clay material of the present invention. FIG. 2 is a pore distribution curve obtained by the nitrogen adsorption/desorption method of the microporous clay material of the present invention.
Figure 3 shows a smectite-type mineral in a swollen state containing water between its layers. FIG. 4 shows the state before drying in a production method in which a water-soluble synthetic polymer compound and an inorganic substance are inserted between the layers of a smectite mineral.

Claims (1)

[Claims] 1. A microporous clay containing a neutral water-soluble synthetic polymer compound and an inorganic substance selected from silica and silica-alumina between the layers of a smectite mineral, and having an interlayer spacing of 20 angstroms or more. material.