JPS6246489B2 - - Google Patents

Description

Detailed Description of the Invention The present invention provides a method for producing a porous clay material having a pore diameter of 20 angstroms or more, more specifically, a method for producing a porous clay material having a pore diameter of 20 angstroms or more, and more specifically, a method for producing a porous clay material having a pore diameter of 20 angstroms or more, and more specifically, a method for producing a porous clay material having a pore size of 20 angstroms or more, and more specifically, a method for producing a porous clay material having a pore size of 20 angstroms or more. The present invention relates to a method for producing a porous clay material maintained as described above.

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. 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 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 ends up being about 10 angstroms.

Furthermore, in conventional production methods, for example, JP-A-54-5884 and JP-A-54-16386, smectite-type minerals are mixed with water and cationic inorganic substances, and the cationic inorganic substances are mixed with interlayer exchangeable cations and ions. Since the production method involves exchange and then hydrolysis, the interlayer distance of the product is about 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.

The present inventors first added a water-soluble polymer compound that dissolves in water and has a neutral charge, a cationic oxide or a cationic hydroxide, and water to a smectite mineral, and then A method was developed to obtain microporous clay with a pore diameter of 20 angstroms or more by mixing, drying, and firing (Japanese Patent Application Laid-open No. 131878/1982), but as a result of further research, the above-mentioned method was developed. It is easier to use polymeric silica or silica sol instead of cationic oxide or hydroxide and to gel it.
It was discovered that microporous clay having a pore diameter of angstroms or more can be obtained, and the present invention was completed.

That is, this invention provides a microporous clay characterized by adding a neutral water-soluble polymer compound, silica sol, and water to a smectite mineral, mixing thoroughly, gelling the silica sol, and then drying and firing. It provides a method for manufacturing the material.

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 polymer compound used in this invention is neutral, that is, shows neutral charge when dissolved in water, and examples of such compounds include starch, konjac, agar, molasses, There are natural polymeric compounds such as gum arabic, glue, and gelatin, and synthetic polymeric compounds such as polyvinyl alcohol and polyethylene oxide.

Furthermore, in the present invention, the silica sol used as an inorganic material to be interposed between layers of smectite minerals to create a layer spacing of at least 20 angstroms is formed into a spherical shape by polymerizing a large number of silicon oxides. A wide variety of ball diameters are prepared, ranging from several tens of angstroms to several hundred angstroms. In addition, the spherical surface has a strong negative charge, and when cations such as Ca ²⁺ and Al ³⁺ coexist, they react rapidly, neutralizing the surface charge, forming an even larger polymer, and finally reducing the charge. becomes a zero gel.

In the production of this invention, first, a smectite mineral, water, a neutral water-soluble polymer compound, and silica sol are mixed. The amount of water is smectite mineral 1
0.4ml or more per gram. Further, the concentration of the aqueous solution of the neutral water-soluble polymer compound is set in a range that exhibits fluidity at a viscosity below that of which the solution slightly flows when tilted. Silica sol per gram of smectite mineral
The amount ranges from 0.05 g to 1 g, and if it is less than 0.05 g, it will not form a sufficient column, and if it is more than 1 g, it is disadvantageous to use it because the porosity will decrease.

The order of mixing may be either by mixing a mixed aqueous solution of a neutral water-soluble polymer compound and silica sol with a smectite mineral, or by mixing a silica sol with a mixture of a smectite mineral and a neutral water-soluble polymer compound aqueous solution.

The state after mixing is shown in FIG. Here, the silica sol and the spiral line represent a neutral water-soluble polymer compound. In this state, even if silica sol exists between the layers, the appearance of the structural viscosity of the neutral water-soluble polymer compound pushes the space between the layers apart. 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 neutral water-soluble polymer compounds are applied to the interlayers of smectite minerals so that the interlayer distance does not become smaller due to the insertion of silica sol.

Next, the silica sol existing between the layers is gelled. There are two methods of gelation.
Either is fine. One method is to leave the silica sol at room temperature or at temperatures up to 150°C and dry it, thereby removing the water between the layers and causing gelation of the silica sol. Furthermore, by excluding water, the spread of the neutral water-soluble polymer compound is reduced (). Second, gelation of the silica sol occurs by adding cations (consisting of hydrogen ions, metal ions from groups IB to IB of the periodic table, and mixtures thereof) under the conditions. Thereafter, by leaving it at room temperature or at a temperature of up to 150°C and drying it, water between the layers is removed and the spread of the neutral water-soluble polymer compound is reduced (). The amount of cation added is 1×10 ^-4 per gram of smectite mineral.
The range is from 1 x 10 ^-2 mol to 1 x 10 -2 mol, and if it is less than 1 x 10 ^-4 mol, gelation will be insufficient, and if it is more than 1 x 10 ^-2 mol, the porosity will decrease. is disadvantageous. To explain this in more detail,
Silica sol consists of negatively charged amorphous silica particles dispersed in water to form a colloid, and the particles have a spherical shape. -SiOH groups and -OH ^- ions are present 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 disrupted due to concentration or addition of cations, thickening, gelation, aggregation, etc. occur.
The degree of gelation changes depending on the degree of concentration, 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 of 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%. Dehydration of silanol occurs between 400°C and 700°C. No particle change is observed up to this temperature, but at temperatures above the glass transition (T _G ) of about 800° C., surface fusion between silica particles occurs and mechanical strength is observed.

Finally, the neutral water-soluble polymer compound between the layers is incinerated and removed by heating at 300°C to 700°C, forming pillars of inorganic material between the layers ().

Therefore, another feature of the present invention is that the silica sol is gelled between the layers of the smectite mineral, fixed between the layers, and then the neutral water-soluble polymer compound is removed by incineration, thereby forming the fine pores of the smectite mineral with a long interlayer distance. The advantage is that high-quality clay materials can be obtained.

Furthermore, as a result of examining the product of this invention by a nitrogen adsorption/desorption method, it was found to be a microporous material having a pore diameter of 20 angstroms or more, as shown in FIG. Further, the surface area of pores having a diameter of 20 angstroms or more is about 300 m ² /g at maximum, and the total surface area is about 450 m ² /g at maximum. The maximum nitrogen capacity is approximately 0.4 ml/g, the specific volume is approximately 0.8 cm ³ /g maximum, and the porosity is approximately 0.5 maximum.

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 1.0 g of polyvinyl alcohol with a degree of polymerization of 500 and 10 g of water
ml, add 2 ml of a 6.0 weight percent silica sol aqueous solution (manufactured by Catalysts & Chemicals, No. SI-500 diluted with water), and stir and mix. 1.00g of sodium montmorillonite in mixed aqueous solution
Add and further stir and mix. The mixture thus obtained was left in a dryer at 50°C for 1 day, and after drying, it was fired at 500°C in an electric furnace in an air atmosphere for 3 hours.
As a result of examining the pore diameter, surface area, nitrogen capacity, specific volume, and porosity of the product by nitrogen adsorption/desorption method, the average pore diameter was 56 angstroms, and the surface area was 156 m ² /g for pore diameters of 20 angstroms or more. The total surface area was 215 m ² /g, the nitrogen capacity was 0.28 ml/g, the specific volume was 0.68 cm ³ /g, and the porosity was 0.41.

Example 2 0.26g of polyvinyl alcohol with a degree of polymerization of 2000 was added to water.
After dissolving in 7.5 ml, add 2.5 ml of a 7.5 weight percent silica sol aqueous solution (manufactured by Catalysts & Chemicals, No. SI-350 diluted with water), and stir and mix. Sodium montmorillonite in mixed aqueous solution
Add 1.00g and further stir and mix. The resulting mixture was left in a dryer at 50°C for 1 day.
After drying, it was fired in an electric furnace in an air atmosphere at 500°C for 6.5 hours. The pore size, surface area, nitrogen capacity, specific volume, and porosity of the product were investigated using the nitrogen adsorption ^/ desorption method. Total surface area is 216m ² /g, nitrogen capacity is 0.23ml/g,
The specific volume was 0.63 cm ³ /g and the porosity was 0.37.

Example 3 0.52 g of polyvinyl alcohol with a degree of polymerization of 2000 was added to water.
After dissolving in 15 ml, 5 ml of a 7.5 weight percent silica sol aqueous solution (manufactured by Catalysts & Chemicals, No. SI-350 diluted with water) was added, and the mixture was stirred and mixed.
Sodium montmorillonite 1.00 into mixed aqueous solution
g and further stir and mix. The mixture thus obtained was left in a dryer at 50°C for 1 day, and after drying, it was fired at 500°C in an electric furnace in an air atmosphere for 6.5 hours. Pore size, surface area, nitrogen capacity, specific volume of the product,
As a result of examining the porosity using the nitrogen adsorption/desorption method, the average pore diameter was 44 angstroms, the surface area was 160 m ² /g for pores with a diameter of 20 angstroms or more, the total surface area was 251 m ² /g, and the nitrogen capacity was 0.26 ml. /g,
The specific volume was 0.66 cm ³ /g and the porosity was 0.39.

Example 4 0.4 g of polyvinyl alcohol with a degree of polymerization of 2000 was added to water.
After dissolving in 10 ml, add 3.5 ml of a 3.0 weight percent silica sol aqueous solution (manufactured by Catalysts & Chemicals, No. SI-500 diluted with water), and stir and mix. Sodium montmorillonite in mixed aqueous solution
Add 1.00g and further stir and mix. Add 20% by weight CaCl ₂ aqueous solution to the mixture thus prepared.
After adding 2.5 ml and stirring and mixing, the mixture was left in a dryer at 50°C for 1 day, and after drying, it was fired at 500°C in an electric furnace in an air atmosphere for 15 hours. As a result of examining the pore diameter, surface area, nitrogen capacity, specific volume, and porosity of the product by nitrogen adsorption/desorption method, the pore diameter was 115 angstroms on average, and the surface area was 79 m ² /g for pore diameters of 20 angstroms or more. The total surface area is 124m ² /g,
The nitrogen capacity was 0.34 ml/g, the specific volume was 0.74 cm ³ /g, and the porosity was 0.46.

Example 5 0.4 g of polyvinyl alcohol with a degree of polymerization of 2000 was added to water.
After dissolving in 10ml, add 1.00g of sodium montmorillonite and stir to mix. into the mixture
Add 3.5 ml of a 3.0 weight percent silica sol aqueous solution (manufactured by Catalysts Kasei Kogyo Co., Ltd., No. SI-500 diluted with water), and further stir and mix. 2.5 ml of a 20 weight percent CaCl ₂ aqueous solution was added to the resulting mixture, stirred and mixed, and then placed in a dryer at 50°C for 1 hour.
Leave it for a day, then dry it in an electric furnace in an air atmosphere at 500℃.
Baked for 15 hours. As a result of investigating the pore size, surface area, nitrogen capacity, specific volume, and porosity of the product by nitrogen adsorption/desorption method, the average pore size was 102 angstroms, and the surface area was 20 angstroms or more.
109m ² /g, total surface area 173m ² /g, nitrogen capacity 0.30ml/g, specific volume 0.70cm ³ /g, porosity 0.43
It was hot.

Example 6 1.0 g of polyvinyl alcohol with a degree of polymerization of 500 and 10 g of water
ml, add 0.35 ml of a 28 weight percent silica sol aqueous solution (manufactured by Catalysts & Chemicals, No. SI-500), and stir and mix. Add 1.00 g of sodium montmorillonite to the mixed aqueous solution and stir and mix. 3.0 ml of a 3.2 weight percent AlCl _{3.6H 2} O aqueous solution was added to the resulting mixture;
After stirring and mixing, the mixture was left in a dryer at 50°C for 1 day, and after drying, it was fired at 500°C in an electric furnace in an air atmosphere for 3 hours. Product pore size, surface area, nitrogen capacity,
As a result of examining the specific volume and porosity using the nitrogen adsorption/desorption method, the average pore diameter was 40 angstroms, and the surface area was 281 m ² /
g, total surface area is 433 m ² /g, nitrogen capacity is 0.37
ml/g, specific volume was 0.77 cm ³ /g, and porosity was 0.48.

Example 7 1.0 g of polyvinyl alcohol with a degree of polymerization of 500 and 10 g of water
ml, add 0.35 ml of a 28 weight percent silica sol aqueous solution (manufactured by Catalysts & Chemicals, No. SI-500), and stir and mix. Add 1.00 g of sodium montmorillonite to the mixed aqueous solution and stir and mix. 0.9 ml of a 3.2 weight percent AlCl _{3.6H 2} O aqueous solution was added to the resulting mixture;
After stirring and mixing, the mixture was left in a dryer at 50°C for 1 day, and after drying, it was fired at 500°C in an electric furnace in an air atmosphere for 3 hours. Product pore size, surface area, nitrogen capacity,
As a result of examining the specific volume and porosity using the nitrogen adsorption/desorption method, the average pore diameter was 58 angstroms, and the surface area was 203 m ² /
g, total surface area is 291 m ² /g, nitrogen capacity is 0.38
ml/g, specific volume was 0.78 cm ³ /g, and porosity was 0.49.

Example 8 1.0g of polyvinyl alcohol with a degree of polymerization of 2000 was added to water
After dissolving in 10 ml, add 0.35 ml of 28 weight percent silica sol aqueous solution (manufactured by Catalysts & Chemicals, No. SI-500).
Add and stir to mix. Add 1.00 g of sodium montmorillonite to the mixed aqueous solution and stir and mix. 3.0 ml of a 3.2% by weight AlCl ₃ 6H ₂ O aqueous solution was added to the resulting mixture, stirred and mixed, and left in a dryer at 50°C for 1 day. After drying, the mixture was heated at 500°C in an electric furnace in an air atmosphere for 30 minutes
Baked for an hour. As a result of investigating the pore diameter, surface area, nitrogen capacity, specific volume, and porosity of the product by nitrogen adsorption/desorption method,
The average pore size is 40 angstroms and the surface area is
140 for pore sizes greater than 20 angstroms
m ² /g, and the total surface area is 208m ² /g, and the nitrogen capacity is
The specific volume was 0.23 ml/g, the specific volume was 0.63 cm ³ /g, and the porosity was 0.37.

[Brief explanation of the drawing]

Figure 1 shows a state in which a layer of smectite minerals is swollen by water. Figure 2 shows a neutral water-soluble polymer compound between the layers of a smectite mineral.
The pore generation process of the manufacturing method performed by inserting silica sol is shown. FIG. 3 is a pore distribution curve of the microporous clay material of the present invention obtained by the nitrogen desorption method.

Claims (1)

[Claims] 1. A method for producing a microporous clay material, which comprises adding a neutral water-soluble polymer compound, silica sol, and water to a smectite mineral, thoroughly mixing the mixture, gelling the silica sol, and then drying and firing.