JP2636183B2 - Synthetic method of interlayer cross-linked clay with improved hydrothermal stability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention provides a method for synthesizing an interlayer-crosslinked clay having improved hydrothermal stability, and is very effective when the interlayer-crosslinked clay is used under hydrothermal conditions.

[0002]

2. Description of the Related Art Heretofore, no method has been known for synthesizing an interlayer crosslinked clay having improved hydrothermal stability.

[0003]

The interlayer-crosslinked clay is synthesized by introducing a pillar of an inorganic oxide such as alumina or zirconia between the silicate layers of the swellable clay mineral. The layer interval corresponding to the pore diameter corresponds to the size of the pillar, and is several to several tens angstroms. Interlayer crosslinked clay has similar pore size and chemical properties to zeolite, and therefore, attempts have been made to use it as a catalyst or catalyst carrier in which zeolite is used, or as a separating material or an adsorbent. Various atmospheres are assumed when the interlayer cross-linked clay is used, and there are cases where the interlayer cross-linked clay is cooled, heated, or used under hydrothermal conditions. If interlayer clay is left under high temperature or hydrothermal conditions, the interlayer spacing shrinks,
The surface area and pore volume are extremely reduced, often causing serious problems in utilization. However, the present invention
It is an object of the present invention to provide a method for synthesizing an interlayer crosslinked clay having improved hydrothermal stability in which shrinkage of a layer interval is small even when left under hydrothermal conditions.

[0004]

The interlayer-crosslinked clay is synthesized by introducing ultrafine particles such as alumina and zirconia between silicate layers of a swelling clay mineral such as montmorillonite and hectorite. A layer space is formed between the silicate layers by the presence of ultrafine particles such as alumina and zirconia. The distance between the silicate layers is called a layer interval, and corresponds to the size of alumina, zirconia, or the like, and the size can be controlled within a range of several to several tens angstroms depending on the preparation conditions. It has been attempted to use interlayer cross-linked clay as a catalyst, a catalyst carrier, a separating material, an adsorbent, etc. by utilizing the layer space. The atmosphere at the time of use is under a low or high temperature or under hydrothermal conditions, and it is desirable that changes in layer spacing, specific surface area, pore volume, and the like during use are as small as possible. However, when the interlayer-crosslinked clay is left under hydrothermal conditions, an extreme decrease in the interlayer spacing is observed. When the interlayer spacing of the interlayer cross-linked clay is extremely reduced, a serious problem occurs in that various functions are not exhibited. However, as a result of intensive studies, the present inventors have found a method for synthesizing an interlayer cross-linked clay having improved hydrothermal stability with a small shrinkage of the interlayer spacing even when left under hydrothermal conditions, and completed the present invention. .

[0005] The interlayer crosslinked clay will be described in detail. Smectite having cation exchange ability and swelling properties is mainly used for the base clay mineral. Smectite contains many clay minerals, and one type of montmorillonite exists in a state where silicate layers are stacked in layers. The silicate layer has a three-layer structure in which both sides of an alumina octahedral layer are sandwiched between silica tetrahedral layers.
Al ³⁺ , the central metal ion of alumina octahedron, is partially isomorphically substituted by Mg ²⁺ or the like having a small charge amount, so that the silicate layer has a shortage of charge. Further, a part of Si ⁴⁺ which is a central metal ion of silica tetrahedron is ^converted to Al
It is isomorphously substituted with a cation with a small charge such as ³⁺ . The silicate layer has a negative charge due to the isomorphous substitution of cations having different charges. In general, the cation exchange capacity is determined by the degree of isomorphous substitution. That is, the cation exchange capacity of smectite having a large amount of isomorphous substitution is large, and that of smectite having a small amount of isomorphous substitution is small. Montmorillonite contains Na ⁺ , Ca ²⁺ , K ⁺ , M between layers to cancel the negative charge of the silicate layer.
It contains cations such as g ²⁺ , and these cations are exchangeable with other cations. Further, montmorillonite swells in water because the bonding strength between the silicate layers is weak.

[0006] Interlaminar crosslinked clays are synthesized by introducing a pillar precursor between the silicate layers of smectite suspended and swollen in water. Since the cation exchange properties of the clay mineral are used in the synthesis, the pyran precursor needs to be cationic. Various cationic inorganic oligomers that can be used as pillar precursors are known. For example, when the pillar is alumina, [Al ₁₃ O ₄ (OH)
₂₄ (H ₂ O) ₁₂ ] ⁷⁺ (G. Johansson, Act
a Chem. Scand. , Vol. 14, p. 7
71 (1960)), when the pillar is zirconia, [Z
r ₄ (OH) ₁₄ (H ₂ O) ₁₀ ] ²⁺ (S. Yamanaka
and G. W. Blindley, Clays
Clay Miner. , Vol. 27, p. 119
(1979)). After these cations are introduced and fixed between the silicate layers by ion exchange, hydrolysis proceeds to form hydroxides. After that, wash with water,
By operations such as drying and heating, an interlayer cross-linked clay having oxides such as alumina and zirconia in pillars is synthesized. The interlayer spacing and the specific surface area of the interlayer-crosslinked clay are slightly different depending on the synthesis method, but the interlayer spacing is about 8 Å and the specific surface area is 300 to 500 m ² / g.

[0007] The hydrothermal stability of the interlayer-crosslinked clay can be evaluated by examining the layer spacing before and after the hydrothermal treatment of the interlayer-crosslinked clay. That is, the interlayer crosslinked clay having low hydrothermal stability has an extremely small layer spacing after the hydrothermal treatment as compared with that before the hydrothermal treatment. On the other hand, the interlayer-crosslinked clay having high hydrothermal stability is almost the same as the interlayer spacing after the hydrothermal treatment is slightly smaller than that before the treatment. The hydrothermal stability test is performed by intercalating the intercalated clay suspended in water in an autoclave.
The treatment is carried out at 180 ° C. for 24 hours, and after standing to cool, it is recovered, dried, and checked for the layer interval by powder X-ray diffraction. The layer spacing is determined by subtracting 9.6 angstroms, which is the thickness of one silicate layer, from the d (001) value obtained by the powder X-ray diffraction method.

The method for synthesizing the interlayer-crosslinked clay having improved hydrothermal stability by attaching carbon according to the present invention will be described for alumina-crosslinked montmorillonite. Alumina-crosslinked montmorillonite is an interlayer-crosslinked clay in which alumina is introduced between silicate layers of montmorillonite. The layer spacing before hydrothermal treatment of the alumina-crosslinked montmorillonite to which carbon was not attached was 8.2 angstroms, and the layer spacing after hydrothermal treatment at 180 ° C. for 24 hours was reduced to 4.7 angstroms. This can be considered that the alumina-crosslinked montmorillonite to which carbon is not attached has low hydrothermal stability. As a result of intensive studies on a method of imparting hydrothermal stability to this alumina-crosslinked montmorillonite having low hydrothermal stability, the present invention has been found. That is, it was found that the hydrothermal stability of the interlayer crosslinked clay was improved by attaching carbon to the interlayer crosslinked clay. Since it is known that organic matter is easily carbonized by hydrothermal treatment, a method of attaching carbon to the interlayer crosslinked clay is performed as follows. First, a suspension of an interlayer cross-linked clay and an organic substance is prepared using water as a solvent. The prepared suspension is subjected to hydrothermal treatment using an autoclave. It is important to select processing conditions under which organic matter is carbonized. In the present invention, a description will be made by selecting a hydrothermal temperature of 180 ° C. and a treatment time of 24 hours. However, since the structural change of smectite occurs when the hydrothermal temperature increases, the hydrothermal temperature is desirably 300 ° C. or lower. After the hydrothermal treatment, the clay recovered by washing and drying is the interlayer-crosslinked clay to which the carbon of the present invention is adhered. The method of carbonizing the organic substance may be any method other than the method of hydrothermal treatment, as long as the organic substance is carbonized. The organic substance used in the present invention is one or a mixture selected from saccharides and their derivatives, amino acids and their derivatives, proteins and hydrophilic organic polymers. Hydrophilic organic polymer
Has various sizes derived from its molecular weight or concentration in water, and any size can be used as long as it can be inserted between the layers of the interlayer-crosslinked clay. The amount of the organic substance to be added to the interlayer-crosslinked clay is desirably equal to or more than that of the interlayer-crosslinked clay, but may be equal to or less than the amount depending on the hydrothermal conditions used.

Hereinafter, the present invention will be described in more detail with reference to Examples.

[0010]

EXAMPLE 20 g of Na-montmorillonite was added to 200 ml of distilled water, stirred and mixed to prepare a suspension. Next, while stirring the suspension, 10 wt% Al ₂ (OH) ₅ Cl.
100 ml of a 2.4 H ₂ O aqueous solution was added little by little, and after the addition was completed, the mixture was allowed to stand at room temperature for 5 days. The clay obtained by filtration was washed with water, dried at 60 ° C, and then heated at 500 ° C for 1 hour to synthesize alumina-crosslinked montmorillonite. The layer spacing of the synthesized alumina-crosslinked montmorillonite was 8.2 angstroms. A suspension was prepared by mixing 0.50 g of the present alumina-crosslinked montmorillonite and 10 ml of an aqueous sucrose solution of various concentrations up to 20 wt%, and subjected to hydrothermal treatment in an autoclave. Hydrothermal treatment condition is hydrothermal temperature 1
At 80 ° C., the treatment time was 24 hours. After the hydrothermal treatment,
The alumina-crosslinked montmorillonite collected by filtration and recovered was washed with distilled water and dried at 60 ° C. Through the above operation, alumina-crosslinked montmorillonite to which carbon was attached was synthesized.

The hydrothermal stability of alumina-crosslinked montmorillonite to which carbon was attached with various concentrations of sucrose was described in Example 1.
The description will be made from to. Hydrothermal stability was evaluated by placing 10 ml of a suspension of carbon-adhered alumina-crosslinked montmorillonite and distilled water in a Teflon container having an internal volume of 30 ml, sealed, and hydrothermally treated at a hydrothermal temperature of 180 ° C. for 24 hours. Was carried out, and the layer spacing of the alumina-crosslinked montmorillonite to which carbon was attached after the hydrothermal treatment was examined. Further, the layer spacing after hydrothermal treatment of alumina-crosslinked montmorillonite to which carbon is not attached is shown as a comparative example.

Example 1 A suspension prepared from 0.50 g of alumina-crosslinked montmorillonite and 10 ml of a 2 wt% sucrose aqueous solution was subjected to hydrothermal treatment to synthesize alumina-crosslinked montmorillonite (interlayer-crosslinked clay A) to which carbon was attached. The layer spacing after drying at 60 ° C. was 7.2 angstroms. A suspension was prepared by adding 10 ml of distilled water to 0.51 g of the interlayer cross-linked clay A, and the layer spacing after the hydrothermal treatment was 6.5 angstroms. The layer spacing after the hydrothermal treatment shrank by 0.7 angstroms.

Example 2 A suspension prepared from 0.50 g of alumina-crosslinked montmorillonite and 10 ml of 4 wt% sucrose aqueous solution was subjected to hydrothermal treatment to synthesize alumina-crosslinked montmorillonite (interlayer crosslinked clay B) to which carbon was attached. The layer spacing after drying at 60 ° C. was 8.2 angstroms. A suspension was prepared by adding 10 ml of distilled water to 0.56 g of the interlayer cross-linked clay B, and the layer interval after the hydrothermal treatment was 7.4 angstroms. After the hydrothermal treatment, the layer interval shrank by 0.8 Å.

Example 3 A suspension prepared from 0.50 g of alumina-crosslinked montmorillonite and 10 ml of a 6 wt% sucrose aqueous solution was subjected to hydrothermal treatment to synthesize alumina-crosslinked montmorillonite (interlayer crosslinked clay C) to which carbon was attached. The layer spacing after drying at 60 ° C. was 8.7 angstroms. A suspension was prepared by adding 10 ml of distilled water to 0.62 g of the interlayer cross-linked clay C, and the layer spacing after the hydrothermal treatment was 8.4 angstroms. The layer spacing after the hydrothermal treatment shrank by 0.3 angstroms.

Example 4 A suspension prepared from 0.50 g of alumina-crosslinked montmorillonite and 10 ml of an 8 wt% aqueous sucrose solution was subjected to hydrothermal treatment to synthesize alumina-crosslinked montmorillonite (interlayer crosslinked clay D) to which carbon was attached. The layer spacing after drying at 60 ° C. was 8.9 angstroms. A suspension was prepared by adding 10 ml of distilled water to 0.71 g of the interlayer cross-linked clay D, and the layer interval after the hydrothermal treatment was 8.5 angstroms. The layer spacing after the hydrothermal treatment shrank by 0.4 Å.

Example 5 0.50 g of alumina-crosslinked montmorillonite and 10 wt%
The suspension prepared from 10 ml of the aqueous sucrose solution was subjected to hydrothermal treatment to synthesize alumina-crosslinked montmorillonite (interlayer crosslinked clay E) to which carbon was attached. The layer spacing after drying at 60 ° C. was 8.9 angstroms. A suspension was prepared by adding 10 ml of distilled water to 0.82 g of the interlayer cross-linked clay E, and the layer spacing after hydrothermal treatment was 8.6 angstroms. The layer spacing after the hydrothermal treatment shrank by 0.3 angstroms.

Example 6 0.50 g of alumina-crosslinked montmorillonite and 12 wt%
The suspension prepared from 10 ml of the aqueous sucrose solution was subjected to hydrothermal treatment to synthesize alumina-crosslinked montmorillonite (interlayer crosslinked clay F) to which carbon was attached. The layer spacing after drying at 60 ° C. was 8.9 angstroms. A suspension was prepared by adding 10 ml of distilled water to 0.90 g of the interlayer cross-linked clay F, and the layer spacing after hydrothermal treatment was 8.8 angstroms. The layer spacing after the hydrothermal treatment shrank by 0.1 angstroms.

Example 7 0.50 g of alumina-crosslinked montmorillonite and 16 wt%
A suspension prepared from 10 ml of the sucrose aqueous solution was subjected to hydrothermal treatment to synthesize alumina-crosslinked montmorillonite (interlayer crosslinked clay G) to which carbon was attached. The layer spacing after drying at 60 ° C. was 8.9 angstroms. A suspension was prepared by adding 10 ml of distilled water to 1.07 g of the interlayer cross-linked clay G, and the layer spacing after hydrothermal treatment was 8.8 angstroms. The layer spacing after the hydrothermal treatment shrank by 0.1 angstroms.

Example 8 0.50 g of alumina-crosslinked montmorillonite and 20 wt%
The suspension prepared from 10 ml of the aqueous sucrose solution was subjected to hydrothermal treatment to synthesize alumina-crosslinked montmorillonite (interlayer crosslinked clay H) to which carbon was attached. The layer spacing after drying at 60 ° C. was 8.9 angstroms. A suspension was prepared by adding 10 ml of distilled water to 1.27 g of the interlayer cross-linked clay H, and the interlayer distance after the hydrothermal treatment was 9.0 angstroms. The layer spacing after the hydrothermal treatment was increased by 0.1 Å.

COMPARATIVE EXAMPLE 1 Distilled water (10 ml) was added to 0.50 g of alumina-crosslinked montmorillonite to which carbon was not adhered and had a layer spacing of 8.2 angstroms to prepare a suspension, which was subjected to hydrothermal treatment. Was about 1/2 of 4.7 angstroms. The interlayer spacing after the hydrothermal treatment shrank by 3.5 angstroms.

[0021]

The present invention provides an interlayer-crosslinked clay that can be used even under hydrothermal conditions, and alleviates the restriction on the atmosphere in which the interlayer-crosslinked clay can be used.

Claims (2)

(57) [Claims] 1. A method for synthesizing an interlayer crosslinked clay having improved hydrothermal stability by attaching carbon. 2. The method according to claim 1, wherein the carbon is attached by hydrothermal treatment in the presence of one or a mixture of saccharides and their derivatives, amino acids and their derivatives, proteins and hydrophilic organic polymers in the interlayer-crosslinked clay. A method for synthesizing the interlayer-crosslinked clay having improved hydrothermal stability according to claim 1.