JPH11228238A - Bulk molded product having crystalline pore structure and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bulk molded product having a crystalline pore structure and useful for gas-separating membranes, catalysts, membrane reactors and various kinds of other functional materials, and to provide a method for producing the bulk molded product. SOLUTION: The bulk molded product having a crystalline pore structure is obtained by a discharge plasma sintering method comprising charging the crystalline microporous crystal powder (not containing a molding auxiliary and a sintering auxiliary) of zeolite, etc., as raw material powder into a conductive mold and subsequently supplying a pulse electric current under a non- pressurized or pressurized condition. The sintering temperature is preferably 300-700 deg.C. Since the obtained bulk molded product does not contain a different kind of agent such as a molding auxiliary or a sintering auxiliary, specificity based on the crystalline pore structure of the raw material powder can maximally be expressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bulk compact comprising crystalline microporous crystal such as zeolite useful as a gas separation membrane, a catalyst, a membrane reactor, an electronic device, a sensor and the like, and a method for producing the bulk compact.

[0002]

[Wherein M1: monovalent cations such as Na ⁺ and K ⁺ , divalent cations such as M2: Ca ²⁺ and Sr ²⁺ , n≧m]

In the above engineering application, it is necessary to make the crystal powder into a bulk compact having a shape and size suitable for the intended use and usage. Bulk compacts are manufactured by compacting powder with a press or the like and then subjecting it to firing treatment in a firing furnace. It is difficult to mold and sinter green compacts. Therefore, in the conventional manufacturing method, powder compaction and sintering are performed by using a mixed powder in which a crystal powder is mixed with a molding/sintering auxiliary agent (silica, silica-alumina, kaolin viscosity, etc.) of about 10 to 30 wt% as a raw material. Is going.

[0004]

SUMMARY OF THE INVENTION In the above-mentioned bulk compact produced by blending a crystal powder, which is a main raw material component, with a molding aid or a co-agent, the proportion of the main component is equal to the amount of the auxiliary compounded. It becomes low, and the deterioration of characteristics due to the mixture of different kinds of agents cannot be avoided. In order to maximize the specificity based on the crystal structure of the main raw material, it is desired to eliminate the use of auxiliaries and the like and manufacture the bulk compact as a pure product. The present invention provides a novel bulk compact and a method for producing the same in order to meet the above demands.

[0005]

The bulk compact having a crystalline pore structure of the present invention is formed as a spark plasma sintered body using crystalline microporous crystalline powder as a raw material. The raw material powder is a single powder of crystalline microporous crystal without any molding auxiliary or sintering auxiliary as in the conventional method. Therefore, the bulk molded product is
Manufactured as a pure product with no pollution.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Spark plasma sintering method (SPS method:
Spark Plasma Sintering) is a method of pressurizing powder and sintering by pulsed current application. That is, the raw material powder is filled in a conductive mold, a pressure is applied, and a pulsed current is supplied through the mold to generate instantaneous/intermittent spark discharge in the powder particle gap, which accompanies the spark discharge. This is an internal heating type sintering method in which powder is sintered by high energy of high temperature plasma. The discharge point in the powder packed bed is
As the current/voltage application is repeatedly turned on and off, the powder is moved and dispersed throughout the packed bed, and homogeneous heat sintering is performed over the entire powder packed bed.

In FIG. 4, (1) is a conductive mold, which is arranged in a water-cooled vacuum chamber (6).
(M) is a raw material powder filled in the mold (1). (2) and (3) are upper and lower punches that press the raw material powder (M), and the upper punch (2) and the lower punch (3) are attached to the electrodes (4) and (5), respectively, and discharge plasma It is connected to the device controller (7).
The raw material powder (M) is pressed through the upper and lower punches (2) and (3) and is supplied with a pulse current.

According to the spark plasma sintering method, as an effect of uniform heating due to internal heat generation, diffusion is caused only in the surface layer of the raw material particles in a short time and in a relatively low temperature region with high thermal efficiency, so that intergranular bonding is achieved. It can be formed, which allows the nanomaterial to be bulked in the nanosized size. The present invention utilizes this property to realize a crystalline microporous crystalline powder while maintaining the crystal structure of the crystalline powder into a bulk to obtain a compact having a pore structure.

The raw material powder to be subjected to spark plasma sintering for producing the bulk compact of the present invention is crystalline pores represented by the aluminosilicate such as zeolite represented by the above general formula [1]. It is a powder having a structure. Speaking of zeolite, these are roughly classified into natural products and synthetic products, and various kinds of crystals (Si/Al ratio ≈1 to ∞) having different chemical compositions and crystal structures are known. These various crystal powders (single crystal or polycrystal powder) are arbitrarily selected and used according to the intended use of the bulk compact and the like.

The raw material powder is filled in the conductive mold of the discharge plasma sintering apparatus without being mixed with an auxiliary agent such as a molding/sintering auxiliary agent. The conductive mold is graphite,
Examples include alloy tool steel, cemented carbide and the like. The sintering treatment by pulsed current application is performed under no pressure or under pressure. Appropriate pressure (for example, 10 to 1000M) depending on the material type and particle size of the raw material powder used.
It is preferable to carry out pulse current application under the action of Pa) in order to efficiently achieve spark plasma sintering.

The sintering treatment temperature is preferably adjusted within the range of 300 to 700°C. This is because if the temperature is lower than this, the time required for sinter bonding (intergranular bonding) becomes long, while in the higher temperature range, the crystalline pore structure of the particles may be impaired. The sintering temperature can be accurately controlled by the current/voltage, the pulse period, and the like. The time required for the sintering process is, for example, 5 to 15 minutes.

As a bulk compact having a crystalline pore structure of the raw material powder obtained by the above-mentioned discharge plasma sintering, a compact having a shape according to its application, usage, etc., such as a block of a columnar body, a sheet-like product, etc. obtain. By combining the conductive mold and the core, it is of course possible to obtain a hollow body such as a tube as a bulk molded body.

[0013]

Example A bulk compact having the crystalline pore structure of the raw material powder is manufactured by spark plasma sintering. Zeolite powders of H-mordenite powder (Si/Al ratio=115) and silicalite powder (Si/Al ratio: ∞) were used as raw material powders. [Example 1] H-mordenite powder (particle size: 1 to 3 µm) 1
g in a graphite mold and degassed under reduced pressure (20
Pa), a pressure of 40 MPa is applied, and a pulse current is supplied (200 to 400 A, 2 to 2 V, about 22 Hz). The temperature was raised to 500°C by the above pulse energization, and heat-treated in the same temperature range for 10 minutes to obtain a disk-shaped bulk compact (diameter 20 mm × height 3.5
mm)

[Example 2] H-mordenite powder (particle size: 1
~ 3 μm) 100 g was filled in a graphite mold,
Under deaeration and reduced pressure (20 Pa), apply a pressure of 30 MPa and supply a pulse current (2000-3500 A, 3-5 V, approximately 22H
z). The temperature was raised to 500° C. by the above pulse energization, and heat treatment was performed for 20 minutes in the same temperature range to obtain a disk-shaped bulk compact (diameter 60 mm×height 40 mm).

Example 3 Silicalite powder (particle size: 10
(3 μm) is filled in a cemented carbide mold, a pressure of 300 MPa is applied under deaeration and reduced pressure (20 Pa), and a pulse current is supplied (600 to 1000 A, 2 to 3 V, about 22 Hz). The temperature was raised to 500°C by the above-mentioned pulse energization, and heat treatment was performed for 10 minutes in the same temperature range to obtain a disk-shaped bulk compact (diameter 20 mm ×
Height 6.5 mm) was obtained.

FIGS. 1 to 3 show the measurement results of the X-ray intensity (X-ray: Cu-Kα ₁ /40kV/100mA, counter: scintillation) of the raw material powders and bulk compacts thereof in Examples 1 to 3. [FIG. 1: Example 1 (H-mordenite crystal), FIG. 2: Example 2 (H-mordenite crystal),
FIG. 3: Example 3 (silicalite crystals)]. In each figure, (1)
Is a raw material powder, and (2) is a bulk compact. The bulk compacts obtained in each example have a crystalline microporous structure of the raw material powder used. The mechanical strength of the bulk compacts (H-mordenite crystals) of Examples 1 and 2 is about 30 MPa, and that of the bulk compacts of Example 3 (silicalite crystals) is about 50 MPa. It has sufficient stability to withstand the use of various aspects in the application.

Example 4 Silicalite powder (particle size: 10
(3 μm) was filled in a cemented carbide mold, depressurized and depressurized (20 Pa), 300 MPa pressure was applied, pulse current was supplied, and the temperature was raised to each preset temperature range of 100 to 800°C. A bulk compact (disc shape, diameter 20 mm x height) was obtained by performing a spark plasma sintering process that warms and holds for 10 minutes.
6.5mm). The upper part of Table 1 shows the success or failure of the bulk compact (disc shape, diameter 20 mm x height 6.5 mm) at each treatment temperature. In the table, an X mark indicates that the product was easily damaged or collapsed during removal from the mold after the sintering treatment or the subsequent handling process, and was incomplete as a bulk compact, ×
_The mark ₁ has the stability (strength) as a molded product, but shows that the soundness of the crystalline pore structure is impaired due to the treatment temperature being too high. In this way, by discharge plasma sintering at a sintering temperature of 300 to 700° C., a bulk compact having a crystalline pore structure of the raw material powder is obtained.

Comparative Example Silicalite powder (particle size: 10 μ
m) 1 g (without auxiliary compounding) was filled in a mold and degassed under reduced pressure (20
After Pa), electric furnace sintering is performed under a pressure condition of 300 MPa. The sintering temperature was adjusted to each preset temperature in the range of 100°C to 800°C, and the processing time was set to 1 hr. The lower column of Table 1 shows the quality of the bulk compact (disk shape, diameter 20 mm×height 6.5 mm) obtained by the external sintering as described in Example 4 above.
It is shown in contrast to that. The X mark in the table indicates that this bulk molded body is liable to be damaged or collapsed during the die-cutting process after the sintering process or the subsequent handling process, and is an incomplete bulk molded body.

[0019]

[Table 1]

[0020]

INDUSTRIAL APPLICABILITY The bulk compact of the present invention has a crystalline microporous crystal structure of the raw material powder, and unlike the conventional product, contamination due to the mixing of different agents of the compacting/sintering aid is prevented. There is none. Therefore, it is possible to maximize the peculiarity based on the crystal structure of the raw material powder, and expand engineering applications as functional materials in various fields, such as gas separation membranes, catalysts, membrane reactors, electronic devices, and sensors. -It is possible to diversify.

[Brief description of drawings]

FIG. 1 is an X of a bulk compact of the present invention and a raw material powder thereof.
It is a graph which shows a line diffraction pattern.

FIG. 2 is an X of the bulk compact of the present invention and the raw material powder thereof.
It is a graph which shows a line diffraction pattern.

FIG. 3 shows X of the bulk compact of the present invention and the raw material powder thereof.
It is a graph which shows a line diffraction pattern.

FIG. 4 is a schematic explanatory diagram of spark plasma sintering.

[Explanation of symbols]

1: Conductive mold 2, 3: Punch 4, 5: Electrode 6: Chamber 7: Discharge plasma device controller M: Raw material powder

Claims (4)

[Claims] 1. A bulk compact having a crystalline pore structure, which is formed by spark plasma sintering of crystalline powder of crystalline microporous body. 2. The bulk compact according to claim 1, wherein the crystalline powder of the crystalline microporous body is a zeolite powder. 3. A crystalline microporous crystal powder is filled in a conductive mold, and a pulsed current is supplied under pressure or without pressure to perform spark plasma sintering. The method for producing a bulk molded article according to 1. 4. The method for producing a bulk compact according to claim 3, wherein the sintering temperature is 300 to 700° C.