JPH0672066B2 - Method for producing porous carbon particles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing spherical pellet-shaped porous carbon particles suitable as a catalyst carrier, a soil conditioner, and the like.

[Conventional technology]

The present applicant has developed a porous carbon particle having a structure in which glassy carbon is formed and adhered to the surface layer of carbon black pellet for the purpose of a heat insulating material. (JP-A-63-190767). The state of pore distribution formed in this type of carbon black-based porous carbon particles, pore volume,
Properties such as specific surface area largely depend on the particle size of carbon black used as the substrate and the grade of the structure. For example, regarding the average pore radius of the grain structure, in the case of carbon black having the same level of DBP oil absorption, which is an index of the structure, it varies fairly accurately according to the size of the particle size. However, particle size 150-3000
Å, DBP oil absorption 60 ~ 200ml / 100g The average pore radius when using a carbon black of a normal type as a base material with characteristics of
It fluctuates only within a very micro range of 0.01 to 0.1 μm.

[Problems to be Solved by the Invention]

For the reasons described above, the porous carbon particles formed by using carbon black alone as a base material have a problem that they cannot be applied to a catalyst carrier or a soil conditioner that requires a wide pore distribution. there were.

Therefore, an object of the present invention is to provide carbon black as a raw material component with a wide pore distribution in the range of 0.01 to 100 μm,
An object of the present invention is to provide a method for producing porous carbon particles having excellent bulk density and pore volume characteristics.

[Means for Solving the Problems]

The method for producing porous carbon particles according to the present invention for achieving the above-mentioned object is to defibrate wood pulp in a carbonizing resin solution.
Rolling granulation using a solution or emulsion in which a dry pulp component and carbon black are blended and a thermo-volatile binder made of a thermoplastic resin and a carbonizing binder made of a thermosetting resin or tar pitch are mixed as a granulating medium. The composition is characterized in that the surface of the granulated pellets is coated with the same kind of resin as the carbonizing binder and then carbonized by firing.

The types of wood pulp used in the present invention include dissolving pulp, or various pulps including sulphide pulp, kraft pulp, semi-chemical pulp, chemiground pulp, thermomechanical pulp, refinery ground pulp, groundwood pulp, and straw and hemp. The paper-making pulp can be mentioned, but long-fiber kraft pulp having a high content of impurities and a high strength is effectively used. These wood pulps are first defibrated in a carbonizing resin solution with a stirring device having a rotary cutter such as a juicer mixer, filtered, and dried to produce a defibrating pulp component to which a carbonizing resin is attached. A solution in which a furan-based resin is dissolved in an organic solvent can be applied as the carbonizing resin solution, but it is preferable to use an aqueous solution of a phenol resin which is easy to control the concentration and handle.

The type of carbon black applied is not particularly limited, and it has a particle size and structure suitable for forming the desired pore size from ordinary furnace black, thermal black, channel black, lamp black, acetylene black, etc. Select to use.

The mixing ratio of the pulp component and carbon black is determined in consideration of the desired pore distribution, pore volume, specific surface area, etc., but the weight ratio (P / CB) is 10:90 to 80:20, especially 20. : 80
It is preferable to set in the range of to 70:30. The blending of pulp components exceeding this range leads to a decrease in the strength of the structure after carbonization by firing, and when the carbon black exceeds the above range, the grain strength increases, but the formation of macropores due to the addition of pulp is diminished. It

The blend of pulp component and carbon black is then tumbled into small spheres using a pin type granulator, such as is commonly used for pelletizing carbon black. On this occasion,
As the granulating medium, a solution or emulsion in which a heat-volatile binder made of a thermoplastic resin and a carbonizing binder made of a thermosetting resin or tar pitch are mixed is used.

The heat fusible binder composed of a thermoplastic resin is a binder having a property that most of the components are decomposed and dispersed in the subsequent firing and carbonization stage, and the type of resin corresponds to polyvinyl alcohol, polystyrene, etc. For this purpose, polyvinyl alcohol is effectively used.

The carbonizing binder is a binder having the property that most of the components remain carbonized in the subsequent firing step, and a phenol or furan thermosetting resin or tar pitch is used.

The mixing ratio of these heat volatile binder and carbonizing binder is appropriately set according to the target pore structure,
It is preferable to set the amount of the resin component of the binder as a whole to 40% by weight or less with respect to the total amount of the pulp component and the carbon black, and addition of more than this will be an obstacle to smooth pore formation.

The granulated pellets thus obtained are dried and then coated with a phenolic or furan-based resin of the same type as the carbonizing binder. This surface coating treatment is, for example, by spraying down a solution of phenol resin or furan resin into a granulated pellet layer packed in a column, or spraying the resin solution while rolling the granulated pellets in a rotating cylindrical tube, It can be performed by a method of heat curing.

The granulated pellets thus surface-coated are finally fired in a non-oxidizing atmosphere at a temperature of 700 ° C or higher to volatilize the heat-volatile resin component and carbonize the carbonizable resin component. Thus, the porous carbon particles of the present invention are manufactured.

[Action]

The pulp component blended as a raw material in the above step uniformly disperses in the carbon black in the granulation stage to form a fibrous skeleton, and partly volatilizes in the firing stage to contribute to pore formation, and the rest remains as it is. Carbonizes and functions to maintain grain strength.

In addition, the heat volatile resin component of the binder serving as the granulation medium helps shape with the carbonizing binder shared in the granulation process, and has a function of volatilizing and forming mainly macroscopic pores in the firing step. Eggplant On the other hand, the thermosetting resin constituting the carbonizing binder functions to carbonize as it is and form a strong grain structure.

In addition, the carbonized resin coated on the granulated pellets is carbonized to form a very strong and smooth surface layer to prevent the carbon black component from scattering, and it becomes a perfect sphere to achieve good transferability required for handling. give.

These functions act in combination and synergistically to have a wide pore distribution from the micropores in the carbon black structure in the range of 0.01 to 0.1 μm to the macropores in units of 100 μm, with low bulk density and high It becomes possible to produce porous carbon particles having a pore volume, a high specific surface area and excellent strength characteristics.

〔Example〕

 Hereinafter, examples of the present invention will be described in comparison with comparative examples.

Examples 1 to 5 and Comparative Example Wood pulp (LBKP) was added to a juicer mixer together with a 10% concentration aqueous solution of a phenol resin [“Sumilite Resin PR-50781” manufactured by Sumitomo Durez Co., Ltd.] and stirred to defibrate. After that, it was filtered. This was dried at 170 ° C., then put in a juicer mixer again, and dry-stirred to sufficiently disintegrate.

Pulped pulp component, average particle size 38nm, iodine adsorption amount
MAF Class Furnace Black CB [made by Tokai Carbon Co., Ltd., "Ceast" with characteristics of 53mg / g, DBP oil absorption 133ml / 100g
116 "] was weighed at the ratio shown in Table 1.

Polyvinyl alcohol [Kanto Chemical Co., Ltd., molecular weight 2700, silicidation degree 78-82 mol%], which is a heat-volatile binder equivalent to 10% by weight (resin content) of the above pulp component and carbon black, relative to the total amount. ] 7% solution and 10% same
(Resin content) Phenolic resin as a carbonizing binder in an amount equivalent to (resin content) "Sumilite Resin PR-5078" manufactured by Sumitomo Dures Co., Ltd. The particles were crushed, and those having a particle diameter of 1 to 2 mm were classified and collected, and dried at 170 ° C.

The granulated pellets were transferred to a rotating drum, and while rotating at 10 rpm, a 20% aqueous solution of the same phenolic resin as the carbonizing binder was sprayed to evenly wet the surface. Then, the resin on the surface was heated and cured at a temperature of 200 ° C., and then carbonized by firing at a temperature of 1000 ° C. in a firing furnace kept in a nitrogen gas atmosphere.

Various characteristics of the porous carbon particles thus obtained were measured, and the values are shown in Table 2.

From the results of Table 1, the porous carbon particles according to the example in which the defibrated pulp after the resin treatment is blended all have improved porous structure characteristics such as bulk specific gravity, specific surface area, and pore volume, as compared with the comparative example, It can also be seen that the thermal conductivity is significantly reduced. The strength characteristics of the examples are slightly lower than those of the comparative examples. Although such a reduction in strength is not a problem for practical use, in the case of Example 5 in which the pulp blending ratio was 90, the insufficient strength became remarkable.

〔The invention's effect〕

As described above, according to the present invention, it is possible to produce high-performance porous carbonaceous particles having a wide range of porosity distribution, a low density, a high specific surface area, and a structure having a high pore volume, while having excellent particle strength. be able to. Therefore, it is expected to be useful in fields of application such as catalyst carriers and soil conditioners, which require a wide range of pore distribution properties.

Claims (2)

[Claims] 1. A pulp composition obtained by defibrating and drying wood pulp in a carbonizing resin solution and carbon black are blended together, and a heat fusible binder made of a thermoplastic resin and a carbonizing agent made of a thermosetting resin or tar pitch. Porous carbon particles characterized by rolling granulation using a solution or emulsion in which a hydrophilic binder is mixed as a granulation medium, coating the surface of the granulated pellets with a resin of the same type as the carbonizable binder, and then calcining and carbonizing. Manufacturing method. 2. The carbonizing resin solution is an aqueous phenol resin solution,
The method for producing porous carbon particles according to claim 1, wherein the thermoplastic resin forming the heat-volatile binder is polyvinyl alcohol, and the thermosetting resin forming the carbonizing binder is a phenol resin or a furan resin.