JPH03103375A - Production of cellular carbon grain - Google Patents

Abstract

PURPOSE:To obtain cellular carbon grains having a wide pore distribution and excellent bulk density and pore volume characteristics by defibrating wood pulp in a carbonizable resin solution, blending the resultant pulp component with carbon black, granulating the prepared blend using a volatile binder and carbonizable binder, then coating the prepared granulated pellets with a carbonizable binder and calcining the coated pellets. CONSTITUTION:Wood pulp (preferably long fibrous kraft pulp) is subjected to defibration treatment in a carbonizable resin solution, preferably in an aqueous solution of a phenolic resin using a stirrer having a rotating cutter and subsequently dried. The resultant pulp component and carbon black are mixed at (10:90)-(80:20), preferably (20:80)-(70:30) weight ratio and a solution or emulsion of a heat-volatile binder composed of a thermoplastic resin and a carbonizable binder composed of a thermoplastic resin or tar.pitch is added to tumble and granulated the aforementioned mixture. The surfaces of the granulated pellets are then subjected to coating treatment with a resin of the same kind as that of the above-mentioned carbonizable binder, calcined and carbonized to afford cellular carbon grains.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing porous carbon particles in the form of spherical pellets suitable as catalyst carriers, soil improvement materials, and the like. [Prior Art] As porous carbon grains, a structure in which glassy carbon is deposited on the surface layer of carbon black pellets has been developed by the present applicant for the purpose of heat insulation (Japanese Patent Laid-Open No. 63 -190767). The characteristics such as the state of pore distribution, pore volume, and specific surface area that are determined by this type of carbon black-based porous carbon particles largely depend on the particle size of the carbon black used as a base material and the grade of the structure. ．． For example, when looking at the average pore radius of the grain structure, in the case of carbon blacks having the same level of DBP oil absorption, which is an index of structure, it varies quite accurately depending on the particle size.

However, particle size 15~3000, DBP oil absorption 160~
200 1II. /100g when using a standard type of carbon black as a base material, the average pore radius is 0.
．． It fluctuates only within a very narrow range of 0.01 to 0.1 μm.

[Problem to be solved by the invention]

For the reasons mentioned above, porous carbon particles formed using carbon black as a base material have the problem that they cannot be used as catalyst supports or soil improvement materials that require a wide pore distribution. there were.

Therefore, the object of the present invention is to use carbon black as a raw material component with 0. The object of the present invention is to provide a method for producing porous carbon particles having a wide pore distribution in the range of O1 to 100μ and excellent bulk density and pore volume characteristics.

[Means to solve the problem]

In order to achieve the above object, the method for producing porous carbon particles according to the present invention involves defibrating and disintegrating wood pulp in a carbonizing resin solution.
Rolling granulation using a solution or emulsion of a mixture of dried pulp components and carbon black, and a mixture of a thermovolatile binder made of a thermoplastic resin and a carbonizable binder made of a thermosetting resin or tar/pitch as a granulation medium. The structure is characterized in that the surface of the granulated pellet is coated with the same type of resin as the carbonizable binder, and then fired and carbonized.

Types of wood pulp used in the present invention include dissolving pulp, sulfide pulp, kraft pulp, semi-cage pulp, cage ground pulp, thermomechanical pulp, refinery ground pulp, groundwood pulp, and other pulps such as straw and hemp. Various types of paper pulp can be used, but kraft pulp, which has long fibers and has low impurity content and high strength, is particularly effectively used. These wood pulps are first defibrated in a carbonizing resin solution using a stirrer equipped with a rotary cutter such as a juicer 5 kisser, then filtered and dried to produce defibrated pulp to which the carbonizing resin is attached. Although a solution prepared by dissolving a furan-based resin in an organic solvent can be used as the carbonizable resin solution, it is preferable to use an aqueous solution of a phenol resin, which is easy to control the concentration and handle.

There are no particular restrictions on the applicable type of carbon blank, and it can be selected from ordinary furnace black, thermal black, channel black, lamp blank, acetylene black, etc., and has a particle size and structure that matches the desired pore size. Select and use.

The mixing ratio of the pulp component and carbon black is determined by taking into consideration the desired pore distribution, pore volume, specific surface area, etc., but the weight ratio (P/CB) is 10:90 to 80.
:20, particularly preferably in the range of 20:80 to 70230. Combinations with pulp content exceeding this range will lead to a decrease in the strength of the structure after carbonization, and if carbon black exceeds the above range, grain strength will increase, but the formation of macropores due to the addition of pulp will result. will be reduced.

The pulp component and carbon black blend is then tumble granulated into small spheres using a bottle-type granulator, such as those commonly used to pelletize carbon black. On this occasion,
As the granulation medium, a solution or emulsion is used in which a heat-volatile binder made of a thermoplastic resin is mixed with a carbonizable six-ingredient made of a thermosetting resin or tar pitch.

A thermovolatile binder made of a thermoplastic resin is a caking material whose components are mostly dissociated and lost during the subsequent sintering or carbonization step, and the types of resin include polyvinyl alcohol, polystyrene, etc. Polyvinyl alcohol is effectively used for the purpose of the invention. Furthermore, the carbonizable binder is a binding material in which most of the components remain carbonized during the subsequent firing stage, and phenolic or furan thermosetting resin or tar pitch is used.

The mixing ratio of these heat-volatile binders and carbonizable binders is appropriately set depending on the desired pore structure.
It is best to set the resin content of the entire binder to 40% by weight or less based on the total amount of pulp components and carbon black; addition of more than this will be detrimental to smooth pore formation.

After the obtained granulated pellets are dried, they are coated with a phenolic or furan resin of the same type as the carbonizable binder. This surface coating treatment can be carried out, for example, by spraying a solution of phenol resin or furan resin onto a layer of granulated pellets filled in a column, or by spraying the same resin solution while rolling the granulated pellets in a rotating cylindrical tube. This can be done by heating and curing.

The granulated pellets surface-coated in this way are finally burned in a non-oxidizing atmosphere at a temperature of 700°C or higher to volatilize the heat-volatile resin and release the carbonizable resin. The porous carbon grains of the present invention are produced by carbonizing. [Function] The pulp component blended as a raw material in the above process is uniformly dispersed in the carbon black in the granulation stage to form a fibrous skeleton, and in the burning stage, a part of it evaporates and forms a bore shape or The remaining part is carbonized as it is and functions to maintain grain strength.

In addition, among the binders that serve as the granulation medium, thermovolatile resins or other resins help shape the resin together with the carbonizable binder, which is also used in the granulation process, and volatilizes during the firing stage to mainly form macroscopic pores. It has the effect of

On the other hand, the thermosetting resin that binds the carbonizable binder functions to remain carbonized and form a strong grain structure.

Furthermore, the carbonized resin that coats the granulated pellets carbonizes to form an extremely strong and smooth surface layer, which prevents the scattering of Rikibon black components, and also forms a perfect spherical shape, which is required for good handling. Provides translocation properties. These functions act in a complex and synergistic manner, resulting in carbon black having a wide pore distribution ranging from micropores in the 0.01 to 0.1 μm range to macropores in the 100 μm range, resulting in low It becomes possible to produce porous carbon grains with bulk density, high pore volume, high specific surface area and excellent strength properties.

〔Example〕

Examples of the present invention will be described below in comparison with comparative examples.

Examples 1 to 5, Comparative Example Wood pulp (LBKP) was mixed with 10% phenolic resin [Sumitomo Durez ■, "Sumilight Resin PR-5"
0781″] The mixture was put into a juicer and a water bottle, stirred and defibrated, and then filtered.

After drying this at 170°C, it was again placed in a juicer and dry stirred to thoroughly defibrate it.

A certain amount of defibrated pulp, average particle size 3811#l, iodine adsorption 153+eg/g, DBP oil absorption 133
MAF grade furnace black CB [manufactured by Tosei Carbon ■, "Sheest 116"] having a characteristic of iN/100g was weighed in the proportions shown in Table 1.

Table 1 A certain amount of the above pulp and carbon black were mixed with polyvinyl alcohol (manufactured by Kanto Kagaku ■, molecular weight: 2
700, degree of saponification 78-82 mol%] 7% solution and the same 1
0% (resin content) of a phenolic resin (manufactured by Sumitomo Durez ■, "Sumilight Resin PR-5078"), which becomes a carbonizable binder, was mixed with a granulating medium mixed with a phenol resin (manufactured by Sumitomo Durez ■, "Sumilight Resin PR-5078") in a pin-type granulator. The granulated pellets were separated and collected, and dried at 170°C.The granulated pellets were transferred to a rotating drum, and while rotating at 10 rpm, 20% of the same phenolic resin as the carbonizable binder was added.
% aqueous solution was sprayed to evenly wet the surface. Then,
After the resin on the surface was heated and hardened at a temperature of 200°C, it was fired and carbonized at a temperature of 1000"C in an incinerator maintained in a nitrogen gas atmosphere.

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

From the results in Table 1, the porous carbon grains according to the examples containing the resin-treated defibrated pulp have all improved porous structure characteristics such as bulk specific gravity, specific surface area, and pore volume, compared to the comparative examples. It is also observed that the thermal conductivity decreases significantly. Note that the strength properties of the examples tend to be slightly lower than those of the comparative examples. Although this degree of decrease in strength is not a practical problem, in the case of Example 5 where the pulp blending ratio was 90, the strength was noticeably insufficient.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to produce high-performance porous carbonaceous grains that have a wide range of porosity distribution, have a structure of low density, high specific surface area, and high pore volume, and have excellent grain strength. be able to. Therefore, it is expected to be particularly useful in applications such as catalyst supports and soil improvement materials, which require a wide range of pore distribution properties.

Claims (1)

[Claims] 1. A pulp component obtained by defibrating and drying wood pulp in a carbonizing resin solution is blended with carbon black, and a thermovolatile binder made of a thermoplastic resin and a thermosetting resin or tar pitch are blended. A porous pellet is characterized in that a solution or emulsion mixed with a carbonizable binder consisting of is granulated by rolling as a granulation medium, the surface of the granulated pellets is coated with a resin of the same type as the carbonizable binder, and then fired and carbonized. A method for producing quality carbon grains. 2. The porous material according to claim 1, wherein the carbonizable resin solution is an aqueous phenol resin solution, the thermoplastic resin constituting the heat-volatile binder is polyvinyl alcohol, and the thermoplastic resin constituting the carbonizable binder is a phenol resin or a furan resin. Method for producing carbon grains.