JPS6141842B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing porous carbon particles.
Specifically, the present invention relates to a method for producing small-diameter porous carbon particles with good handling properties (ease of handling of particles), particularly fluidity, and high fracture strength at a high yield. BACKGROUND ART A porous carbon material composed of carbon black and a carbon binder has been known as a porous carbon material used as a catalyst carrier, a polymeric substance adsorbent, and the like. This porous carbon material has 80~5000
Carbon black with a particle size range of Å units is mixed with a thermosetting resin such as phenol formaldehyde or a thermoplastic resin such as polyacrylonitrile dissolved in a suitable solvent, then molded under pressure, and then carbonized and fired. Manufactured by To produce small-sized granules using the above method, carbon black and a resin binder are generally press-molded and then fired, and after firing, the resulting molded product is crushed to obtain the desired particle size. Make it into granules. However, since the granules obtained by crushing the compact have sharp crushing surfaces, they are easily crushed during use due to mutual contact between the granules.
Fluidity is also poor. Furthermore, when crushing the compact, a large amount of carbon powder is generated, which not only worsens the working environment but also reduces the yield of granules. Therefore, the present inventors conducted research on a method for producing small-diameter porous carbon particles with good fluidity at a high yield.The inventors of the present invention found that, before bringing the carbon black into contact with a resin binder, the carbon black was first shaped into spherical particles. The inventors have discovered that porous carbon particles with a desired small particle size can be obtained by granulating them into a body, immersing them in a resin binder after granulation, and then carbonizing and firing them. The present invention was achieved by confirming that it has good fluidity and sufficient strength for uses such as catalyst carriers. That is, the object of the present invention is to industrially advantageously produce small-sized porous carbon particles having good fluidity and large mechanical strength. This is achieved by granulating carbon black having a particle size of Next, the present invention will be explained in detail. In the method of the present invention, carbon black having a particle size range of 150 to 3000 Angstroms is used. Carbon black generally has individual particles aggregated to form a large chain-like higher-order structure (referred to as a structure), and the position and width of the pore distribution of the porous carbon particles obtained by the method of the present invention are as follows:
It is greatly influenced by the carbon black particle size and structure size. The size of the structure depends on the oil absorption of carbon black.
For example, it is expressed by DBP absorption (capacity of dibutyl phthalate absorbed in 100 g of carbon black, unit: ml/100 g). And with normal carbon black, its DBP absorption is in the range of 60 to 200ml/100g. Therefore, in the method of the present invention, if the DBP absorption amount of carbon black is the same, the average pore radius of the porous carbon particles obtained by using carbon black with a smaller particle size will be smaller; If a material with a large value is used, the average pore radius will become large. Furthermore, if carbon black having a wide particle size distribution is used, porous particles having a slightly wide pore distribution can be obtained. Particle size range 150-3000
By using carbon black with DBP absorption in the range of 60 to 200ml/100g in Å units,
Porous carbon particles having an average pore radius in the range of 100 to 1000 Å can be obtained. The desirable average pore radius of porous carbon particles used as catalyst carriers or adsorbents is 100~
1000 Å, especially 300 to 700 Å, and the particle size of carbon black is appropriately determined from the above range in consideration of its DBP absorption amount and the average pore radius of the porous carbon particles. As for the type of carbon black, various known ones can be used. For example, channel blacks (carbon blacks manufactured by the channel method) such as Mitsubishi Carbon Blacks #100 and #600 (products of Mitsubishi Kasei Corporation), etc. ), Diablack A, Diablack LI, Diablack I, Diablack H, Diablack G
Furnace blacks (carbon blacks manufactured by the furnace method) such as Mitsubishi Kasei Corporation (registered trademark); thermal blacks such as Asahi Thermal FT (trade name of Asahi Carbon Corporation); Carbon black produced by decomposition is preferably used. In the method of the present invention, it is first necessary to granulate the carbon black into spherical bodies. Granulation of carbon black can be carried out according to various known methods, but the rolling method is particularly advantageous because spherical bodies with good fluidity can be easily obtained. Here, to explain the rolling method, the rolling method can be roughly divided into dry method and wet method.The dry method uses a cylindrical kiln with a slight inclination to the central horizontal axis or a truncated conical kiln. In this method, a predetermined amount of carbon black is placed inside the kiln, and the kiln is rotated gently to form granules. On the other hand, the wet method uses a drum equipped with an internal forced stirring mechanism, such as a shaft with specially shaped pins on the surface.
In this method, carbon black is placed inside a drum, the shaft is rotated, and while the carbon black is stirred, approximately the same weight of water as the carbon black is added, thereby granulating. These methods usually yield spherical bodies with a spherical diameter of 0.1 to 5 mm. Next, the obtained spherical bodies are impregnated with a carbonizable binder. Impregnation of the spherical bodies with the carbonizable binder is usually carried out by immersing the spherical bodies in a solvent containing the carbonizable binder. Through this dipping treatment, the carbonizable binder penetrates into the gaps between the carbon black particles, and through the subsequent firing treatment, it has the effect of binding each carbon black particle or structure. As the carbonizable binder, any one can be used as long as it has the effect of binding carbon black and has a carbonization yield of 10% or more upon firing, such as phenol formaldehyde resin, epoxy resin, Examples include thermosetting resins such as urea resin, furan resin, xylene resin, and polyurethane resin, thermoplastic resins such as polyacrylonitrile resin and polystyrene resin, and other tar pitches and synthetic rubbers. When a novolac type resin is used as the phenol formaldehyde resin, a curing agent such as hexamethylenetetramine is used in combination. Any solvent can be used as long as it is volatile and soluble in the carbonizable binder; for example, acetone, methanol, ethanol, butanol, xylene, toluene, cyclohexane, dimethyl. formamide,
Examples include trichloroethane, methyl acetate, and butyl acetate. The amount of the carbonizable binder used is from 0.1 to 1 times the weight of carbon black, preferably 0.2 to 0.4 times the weight, and the amount of the solvent used is from 0.8 to 1.6 times the weight of the carbonizable binder. To be determined accordingly. Alternatively, a method may be employed in which a monomer that can be polymerized as a carbonizable binder is dissolved in a solvent, carbon black is immersed in the solvent, and the monomer is polymerized by heating the solvent or the like. For example, instead of using phenol-formaldehyde resin as a carbonizable binder, phenol and formaldehyde are added in a solvent such as methanol, and then a predetermined amount of carbon black spheres is added, which is then stirred at 110-130°C and 90-130°C.
Just heat it for 120 minutes. Approximately 1 to 15 minutes is sufficient for immersing the carbon black spheres in the solvent containing the carbonizable binder, and the mixture may be gently stirred if necessary. After the carbon black spheres are immersed in a solvent containing a carbonizable binder, the solvent is removed by volatilization, and then carbonized and fired in an inert atmosphere. In order to carbonize and fire the carbon black spherical bodies in an inert atmosphere, an electric furnace or a rotary kiln may be used to heat and fire them in an atmosphere of an inert gas such as nitrogen. At this time, if the firing temperature is low, carbonization will not proceed, and if it is too high, it will not accelerate the progress of carbonization, so it is usually 500 to 1200℃, preferably
The temperature is 500-800℃. Regarding the heating rate, a range of 50 to 1000°C/hour is appropriate. The porous carbon particles thus obtained have a pore volume of 0.05 to 1.0 cc/g, a pore distribution peak ranging from 100 to 1000 Å, and a pore distribution peak of 0.6 It has a breaking strength of ~5.0Kg/ ^mm2 , and even with small particles of 0.1~0.7mm, its angle of repose is in the range of 26~30°, and it has excellent fluidity, so it is used as a catalyst carrier, high It is useful as a molecular substance adsorbent. As described above in detail, according to the method of the present invention, small-diameter porous carbon particles with good handling properties can be produced at a high yield. Next, the present invention will be explained in detail, but the present invention is not limited to the following examples unless it exceeds the gist thereof. Examples 1 to 9 Various carbon blacks (furnace black) having a particle size of 200 to 700 Å were granulated by a wet method, and the obtained carbon black was
It was kept at ℃ for 2 to 3 hours to sufficiently dry it. After drying, the resulting spheres were sieved into sphere diameters ranging from 0.149 to 0.71 mm and from 0.71 mm to 1.68 mm. Table 1 shows the physical properties of these spherical bodies. Next, the carbonizable binders shown in Table 2 below were dissolved in a solvent, and each of the carbon black spheres shown in Table 1 was immersed in the resulting homogeneous solution and gently stirred. Thereafter, the carbon black was heated to 100°C to volatilize and remove the solvent. After removing the solvent, the carbon black spheres impregnated with the carbonizable binder were carbonized in a rotary kiln at 700° C. for 2 hours in a nitrogen stream. The temperature increase rate at this time is also shown in Table 2. After the carbonization treatment, various physical properties of the obtained porous carbon particles were measured. The results are shown in Table 2. The pore distribution of the porous carbon particles obtained in Examples 1, 3, 4, and 5 was measured, and the results are shown in FIG. 1 as curves 1, 2, 3, and 4, respectively. (The horizontal axis is 10gR, and the vertical axis is △V/△
10 gR, where R is the pore radius and V is the pore volume. ) Of these physical properties, the breaking strength of porous carbon particles was measured using an Instron-type tensile and compression measuring tester, TENSILON, after measuring the spherical diameter with an optical microscope.
Pore distribution and pore volume were measured using a POROSIMETRO model (POROSIMETRO
Model) 65-Etsuchi (H) (Italy Carlo
The pore radius range was 75 to 75,000 Å. Regarding the specific surface area, SORPTOMATIC 1800 (Italy Carlo
Using CARLO ERBA (trade name),
The amount of nitrogen adsorbed on porous carbon particles was measured using a low-temperature nitrogen adsorption method, and calculated from this using a multi-point method using the BET equation. In Table 2, the novolak resin was manufactured by adding 30 parts by weight of 30% formalin and hydrochloric acid to 10 parts by weight of phenol, and as a curing agent, hexamethylenetetramine was added in an amount 0.07 times the weight of the novolak resin. used. In addition, as an epoxy resin, epoxy resin Epicoat 828
100 parts by weight of the epoxy resin curing agent Etsutienne (HN)-2200 (trade name of Hitachi Chemical Co., Ltd.) and 70 parts by weight of the epoxy resin curing agent Etsuti-N (HN)-2200 (trade name of Hitachi Chemical Co., Ltd.) and tridimethylaminomethylphenol, a curing accelerator, and TAP (Kayaku 0.5 parts by weight (trade name of Nouri Co., Ltd.) was used.

【table】

【table】

[Table] Comparative example 1 20 g of phenol formaldehyde resin (novolac type) and 1.4 g of hexamethylenetetramine
was dissolved in 80 ml of acetone, and 50 g of carbon black (Diablack H, registered trademark of Mitsubishi Chemical Industries, Ltd.) was added thereto and mixed until homogeneous. After mixing and evaporating the acetone, 200
A pressure of Kg/cm ² was applied to obtain a cylindrical molded body with a diameter of 5 cm and a height of 10 cm. After holding this compact at 110°C for 2 hours to evaporate the acetone, it was transferred to an electric furnace and heated to 600°C at a rate of 400°C/hour in a nitrogen atmosphere. The firing process took a long time. The obtained fired carbon molded body was crushed in a mortar, and the crushed pieces were sieved to obtain granule-like spheres with a diameter of 0.149 to 0.71 mm. The yield of the fruit-like spheres was 65%, and the angle of repose was 40 degrees. On the other hand, the yield and angle of repose of the porous particles in Example 1 were 98% and 28 degrees, respectively. In addition, the yield is calculated by (weight of porous carbon particles of desired spherical diameter/weight of total fired carbon molding) x 100,
The angle of repose was determined by measuring the angle between the generating line and the bottom of the cone when the material was continuously supplied from a funnel onto a horizontal surface and deposited in a conical shape. From the above, it is clear that according to the method of the present invention, porous particles with excellent fluidity can be produced in high yield.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the pore distribution of porous carbon particles obtained by the method of the present invention.

Claims (1)

[Claims] 1. Carbon black having a particle diameter of 150 to 3000 Å is granulated into spherical bodies, the spherical bodies are impregnated with a carbonizable binder, and then carbonized and fired in an inert atmosphere. A method for producing porous carbon particles. 2. In the method described in claim 1,
A method for producing porous carbon particles, characterized in that the spherical diameter of the granulated spheres is in the range of 0.1 to 5 mm. 3. A method for producing porous carbon particles according to claim 1 or 2, wherein the carbonizable binder has a carbonization yield of 10% or more. 4. In the method described in claim 3,
The carbonizable binder is at least one selected from the group consisting of phenol formaldehyde resin, epoxy resin, urea resin, furan resin, xylene resin, polyurethane resin, polyacrylonitrile resin, polystyrene resin, tarpitz, and synthetic rubber. A method for producing porous carbon particles. 5. A method for producing porous carbon particles according to claims 1 to 4, characterized in that the carbonization firing is carried out at a temperature range of 500 to 1200°C.