JPS6212172B2 - - Google Patents

Description

[Detailed description of the invention] The present invention involves inserting a water-soluble polymer and an inorganic substance such as a cationic oxide or cationic hydroxide between the layers of a smectite mineral, and then removing the water-soluble polymer by incineration. This invention mainly relates to a method for producing porous clay materials having pore diameters of 20 angstroms or more.

Smectite-type minerals include montmorillonite, bentonite, chlorite, beidellite, 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. Montmorillonite thus has a large cation exchange capacity and, mainly due to the hydration nature of the exchangeable cations, absorbs a significant amount of water between its layers and exhibits a significantly high swelling property. Other smectite-type minerals also have properties similar to montmorillonite.

Attempts have been made to use the above-mentioned smectite minerals as catalyst carriers or adsorbents by utilizing their interlayer structure.

On the other hand, Figure 1 shows the phase diagram 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). Interlayer distance d ₂ in state
varies 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, when smectite minerals are mixed with water containing cations such as Al ³⁺ and Ca ²⁺ , the positive charge between the layers increases and d ₂ becomes smaller. And if the amount of cations increases, d ₂
eventually becomes about 10 angstroms.

Furthermore, 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 interlayer exchangeable cations. Since this is a production method in which hydrolysis is carried out after drying, the interlayer distance of the product is approximately 10 angstroms or less.

However, when a smectite mineral with a short interlayer distance as described above is used as an adsorbent, a sufficient effect may not be obtained. For example, when refining gasoline using this, low molecular weight hydrocarbons with a small number of carbon atoms in gasoline are inserted between the layers, but relatively large hydrocarbons with a large number of carbon atoms and a relatively large molecular weight are inserted between the layers. It is not inserted, and therefore a sufficient purification effect cannot be achieved.

In view of the above circumstances, this invention was developed as a result of intensive research with the aim of producing a microporous clay material made of smectite minerals with relatively long interlayer distances. It was discovered that a microporous clay material mainly having pore diameters of 20 angstroms or more can be obtained by incinerating and removing water-soluble polymers.

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.

Water-soluble polymers include starch, konnyaku, agar,
There are natural polymers such as molasses, gum arabic, glue, and gelatin, and synthetic polymers such as polyvinyl alcohol and polyethylene oxide. In the present invention, a water-soluble polymer, whether natural or synthetic, is used which has a neutral charge when dissolved in water.

Further, the inorganic substance is selected from one type or a mixture of two or more types of cationic inorganic substances such as cationic oxides and cationic hydroxides. Specifically, the cationic oxide is, for example, alumina prepared by dissolving monoaluminum phosphate in water, and the cationic hydroxide has the general formula [AI ₂ (OH)nCl _6-o ] m , n is approximately 3, and m is 10 or less, polyaluminum chloride is dissolved in water, and an aqueous solution of partially hydrolyzed aluminum hydroxide and chlorides, nitrates, and sulfates of Al, Cr, Bi, and Fe is obtained. Zirconium hydroxide and trinuclear iron acetate obtained by dissolving partially hydrolyzed aluminum hydroxide, chromium hydroxide, bismuth hydroxide, iron hydroxide and ZrOCl in water by adding alkali little by little while stirring. It is an aqueous solution.

In the production of this invention, first, a smectite mineral, water, a water-soluble polymer, and an inorganic substance are mixed. The amount of water is 0.4 per gram of smectite minerals.
ml or more. The concentration of the aqueous solution of the water-soluble polymer is set within a range that exhibits fluidity at a viscosity below the level where the solution slightly flows when tilted. Inorganic matter ranges from 0.05g to 1g per 1g of smectite minerals,
If it is less than 0.05 g, it will not form a sufficient column, and if it is more than 1 g, it cannot be used because the porosity will decrease.

The mixing order is as follows: A mixed aqueous solution of a water-soluble polymer and a cationic inorganic is mixed with a smectite mineral.
Alternatively, any method may be used in which a cationic inorganic substance is mixed into a mixture of a smectite mineral and a water-soluble polymer aqueous solution.

The state after mixing is indicated by I in FIG. Here, the cationic inorganic substance and the spiral line represent water-soluble polymers. In this state, even if a cationic inorganic substance exists between the layers, the appearance of the structural viscosity of the water-soluble polymer forces the interlayers to expand.

To explain this in more detail, in general, in an aqueous polymer solution, the molecular weight of the polymer increases, and as 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. And it becomes rubbery.

The present invention is characterized in that the characteristics of these water-soluble polymers are applied to the interlayers of smectite minerals so that the interlayer distance does not become smaller due to the insertion of cationic inorganic substances.

Next, if the film is left in state I at room temperature or at a temperature up to 100° C., gelation or hydrolysis of the cationic inorganic material occurs, the state shifts to state I, and the cationic inorganic material existing between the layers grows significantly. Furthermore, by drying at room temperature or at temperatures up to 150°C, water between the layers is eliminated, and the water-soluble polymer becomes smaller (). Finally, by heating at 300°C to 700°C to incinerate and remove the water-soluble polymer between the layers, pillars of inorganic matter are created between the layers. ().

Therefore, another feature of the present invention is that these cationic inorganic substances are gelled or hydrolyzed between the layers of smectite minerals to fix them between the layers, and then the water-soluble polymer is removed by incineration to reduce the interlayer distance. The point is that a microporous clay material of long smectite type minerals can be obtained.

Furthermore, as a result of examining the product of this invention by nitrogen adsorption/desorption method, as shown in Fig. 3, it was found to be a microporous material having a pore diameter of 20 angstroms or more, and its total surface area was about 750 m ² /g or less. and also about
It has a nitrogen capacity of 0.1 to about 0.4 ml/g.

These microporous clay materials are useful as catalyst supports and adsorbents and, when oriented, are also useful in high performance thermal insulation materials.

Examples of this invention will be shown below.

Example 1 Polyvinyl alcohol with a degree of polymerization of 2000 in 10 ml of water
Add 1.00g and heat to approximately 60°C while stirring to dissolve. Add 1.00 g of sodium montmorillonite to 10 ml of the dissolved 10 weight percent polyvinyl alcohol aqueous solution, and stir and mix. To this is added 2 ml of an aqueous solution of 0.20 g of polyaluminum chloride dissolved in 2 ml of water, and the mixture is stirred and mixed. The mixture thus obtained was left to dry in a dryer at 50°C for one day. After drying, heat at 500℃ in an electric furnace in an air atmosphere.
It was baked for 3 hours. As a result of examining the pore size, specific surface area, and nitrogen capacity of the product using the nitrogen adsorption/desorption method, the pore size was found to be
The total surface area was 596 m ² /g and the nitrogen capacity was 0.38 ml/g.

Example 2 Polyvinyl alcohol with a degree of polymerization of 2000 in 10 ml of water
Add 1.00g and heat to approximately 60°C while stirring to dissolve. Add 1.00 g of sodium montmorillonite to 10 ml of the dissolved 10 weight percent polyvinyl alcohol aqueous solution, and stir and mix. 5 ml of an aqueous solution of 0.50 g of polyaluminum chloride dissolved in 5 ml of water is added to this, and the mixture is stirred and mixed. The mixture thus obtained was left to dry in a dryer at 50°C for one day. After drying, heat at 500℃ in an electric furnace in an air atmosphere.
It was baked for 3 hours. The pore size of the product is 27 angstroms, the total surface area is 731 m ² /g and the nitrogen capacity is
It was 0.36ml/g.

Example 3 Polyvinyl alcohol with a degree of polymerization of 2000 in 2 ml of water
Add 0.20g and heat to about 60°C while stirring to dissolve. Add 1.00 g of sodium montmorillonite to 2 ml of the dissolved 10 weight percent polyvinyl alcohol aqueous solution, and stir and mix. To this was added 2 ml of a 10 weight percent polyaluminum chloride aqueous solution, stirred and mixed, and then placed in a dryer at 50°C for 1 hour.
Leave it for a day to dry. After drying, it was fired at 500°C for 3 hours in an electric furnace in an air atmosphere. The pore size of the product is 36
The total surface area was 130 m ² /g and the nitrogen capacity was 0.19 ml/g.

Example 4 Polyvinyl alcohol with a degree of polymerization of 2000 in 10 ml of water
Add 0.40g and heat to about 60°C while stirring to dissolve. Add 2 ml of a 10 weight percent polyaluminum chloride aqueous solution to 10 ml of a dissolved 4 weight percent polyvinyl alcohol aqueous solution, stir,
Mix. Add 1.00 g of sodium montmorillonite to the mixed aqueous solution and stir and mix. The resulting mixture was left to dry in a dryer at 50°C for 1 day, and then fired at 500°C for 3 hours in an electric furnace in an air atmosphere. The product had a pore size of 30 angstroms, a total surface area of 320 m ² /g and a nitrogen capacity of 0.27 ml/g.

Example 5 Polyvinyl alcohol with a degree of polymerization of 2000 in 10 ml of water
Add 0.40g and heat to about 60°C while stirring to dissolve. Add 5 ml of 10 weight percent polyaluminum chloride aqueous solution to 10 ml of dissolved 4 weight percent polyvinyl alcohol aqueous solution, stir,
Mix. Add 1.00 g of sodium montmorillonite to the mixed aqueous solution and stir and mix. The resulting mixture was left to dry in a dryer at 50°C for 1 day, and then fired at 500°C for 3 hours in an electric furnace in an air atmosphere. The product had a pore size of 30 angstroms, a total surface area of 231 m ² /g and a nitrogen capacity of 0.13 ml/g.

[Brief explanation of the drawing]

Figure 1 shows a state in which a layer of smectite minerals is swollen by water. Figure 2 shows the pore generation process of a manufacturing method in which a water-soluble polymer and a cationic inorganic substance are inserted between the layers of a smectite mineral. FIG. 3 is a pore distribution curve of the product obtained by the nitrogen desorption method.

Claims (1)

[Scope of Claims] 1. A method for producing a microporous clay material, which comprises mixing a smectite mineral, a water-soluble polymer, an inorganic substance, and water, and then removing the water-soluble polymer by incineration. 2 The smectite mineral is montmorillonite,
The method of claim 1, wherein the material is selected from the group consisting of bentonite, chlorite, beidellite, hectorite, synthetic mica and substituted analogs and mixtures thereof. 3. The production method according to claim 1, wherein the water-soluble polymer is selected from the group consisting of polymers that dissolve in water and exhibit neutral charge, and mixtures thereof. 4. The method of claim 1, wherein the inorganic substance is selected from the group consisting of cationic oxides, cationic hydroxides, and mixtures thereof.