JPH06157158A - Production of hollow carbonaceous spherical body - Google Patents

Abstract

PURPOSE:To obtain a hollow carbonaceous spherical body of light weight excel lent in heat resistance and chemical resistance by allowing a pitch powder having specified softening point and size to adsorb a specified amt. of iodine in an iodine vapor and then treating the powder by heating at specified temp. CONSTITUTION:A pitch powder having 150-300 deg.C softening point and 005-1mm particle diameter is prepared. Then the powder is treated to adsorb 80-250wt.% iodine as the weight increase in an iodine vapor at 80-130 deg.C, and then treated by heating at >=400 deg.C. By this method, first, the surface of pitch particles is hardened, and then the inner pitch which is not hardened is melted by heating. Then the powder is foamed by the gas component produced in the pitch to obtain a hollow carbonaceous spherical powder. The obtd. hollow carbonaceous spherical powder can be used as a light-weight filler or activated to be used as a hollow activated carbon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing hollow carbon spheres having light weight, heat resistance and chemical resistance by treating pitch-type powder, which is a heavy bituminous material, with iodine and then heat-treating it. It is about.

[0002]

2. Description of the Related Art A general carbon material is lightweight and heat resistant, and is used in various fields as one of industrial basic materials because it has characteristics of high elastic modulus and high temperature strength. Further lightweight carbon materials include carbon foam, porous carbon,
There are hollow carbon spheres and the like.

Carbon foam is produced by foaming and curing polyurethane or phenol resin and then firing or molding hollow carbon spheres with a binder and firing (for example, USP 3302999, Inada et al.,
"Carbon", No. 69, p. 36, 1972). These are block-shaped with a bulk density of about 0.5 g / cm ³ . Activated carbon is a typical example of porous carbon, but it does not have pores having an adsorption function of several nm or less as in activated carbon, but there are granular bodies having larger pores.
This is a product in which a nitro group is introduced into carbonaceous material powder such as pitch and carbonaceous mesophase, which is heated and foamed at a temperature of 300 ° C. or higher, and the packing density is 0.1-0.5 g / cm ³ , This is an elastic body having a so-called elastic recovery ability that returns to the original volume by removing the load even if the volume is largely changed by applying a compressive load (Japanese Patent Laid-Open No. 63-139080). Hollow carbon spheres are produced by firing hollow phenolic resin spheres. It is manufactured by rapidly heating, melting, and spraying a pitch with a specific property to which a foaming agent has been added to form hollow spheres, and then firing (Amagi, "Materials", Vol. 16, 31).
P. 5, 1971). This has a bulk density of 0.1-0.3 g / cm ³ close to a true sphere having a particle size of about 75-250 μm. Further, a method for producing hollow carbon spheres has been proposed in which expanded polystyrene spheres are used as a core material, coal powder is attached to the surface of the spheres by granulation, and then the polystyrene spheres are decomposed and removed by firing (Kobayashi et al. , "Carbon", No. 72,
25, 1973). This is the outer diameter of the sphere 0.7-12m
m, bulk density 0.4-0.5 g / cm ³ .

[0004]

As described above, several methods have been proposed for producing multi-cellular carbon and hollow carbon spheres, but the method of the present invention is based on an idea different from these methods. It proposes a new method. That is, in the invention of Japanese Patent Laid-Open No. 63-139080, when the introduced nitro group is decomposed, it is foamed by the heat and gas generated. Amagi's method melts and sprays a pitch having a specific property by rapid heating. Spheroidizing by means of spheroidizing, foaming by the gas generated from the blowing agent, and the method of Kobayashi et al. Uses a core material that is easily removed by thermal decomposition. On the other hand, in the method of the present invention, the surface of the pitch particles is hardened and the uncured pitch inside is melted by heating and foamed by the gas component generated therefrom.

Therefore, a first object of the present invention is to propose a method for producing the above new hollow carbon sphere, and a second object is to obtain a pitch having a specific property as seen in the Amagi method. It is to propose a method that can use an ordinary pitch having a softening point, instead of producing a hollow carbon body.

[0006]

According to the method of the present invention, heavy bituminous pitch is crushed to an appropriate particle size, treated with iodine vapor, and if necessary, adsorbed iodine is removed. The hollow carbon spheres are produced by recovering and then heat treating at a temperature of 400 ° C. or higher.

Pitch, which is a heavy bituminous material, can be used in either coal-based or petroleum-based pitch. For example, coal-based pitch is coal tar, and petroleum-based pitch is obtained by heat treatment of distillation residue oil of crude oil, FCC dencant oil, and heavy bituminous product of naphtha tar. The softening point of these pitches is 150-350 ° C, preferably 150-300 ° C. This is because when the pitch crushed to an appropriate grain size is treated in iodine vapor, it will melt during the treatment unless it is at least 50 ° C. higher than the treatment temperature. However, when the softening point becomes higher than 300 ° C, it becomes very difficult to set the treatment conditions in the iodine vapor for spheroidizing by the heat treatment after the iodine treatment, and if the treatment conditions are gentle, the particles will melt. If you wear it and make the conditions slightly stricter than that, it will not foam and the shape will not change. At 350 ° C or higher, even if a small amount of iodine treatment is performed, it changes to one that does not melt, and spheroidization is almost impossible. Furthermore, the pitch which is a lump is crushed to adjust the particle size, and the particle size is preferably in the range of 0.05-1 mm. Below this value, it becomes very difficult to set the processing conditions for iodine. In other words, if the treatment conditions are mild, it will melt during heat treatment, and if the conditions are made slightly stricter than that, it will not melt at all and the entire pitch will harden,
No foaming. Further, when the particles become large as 1 mm or more, even if they are foamed, they are not spherical, but are worm-like and have many pores, so that they cannot be said to be hollow spheres.

The grain-sized pitch is treated in iodine. This treatment includes a vapor phase method of treating in iodine vapor and a liquid phase method of dissolving iodine in a hydrocarbon such as water, lower alcohol and hexane, and putting pitch in the solution to treat. However, the liquid phase method cannot be used in the present invention. This is because it is not possible to adsorb the amount of iodine required for spheroidization in the pitch. Iodine is a substance with a high vapor pressure of 113 ° C and a boiling point of 184.5 ° C. Therefore, iodine crystals are heated to generate vapor, and a pitch is placed in the vapor for adsorption. Let Specifically, since iodine is highly corrosive when treated in iodine vapor, put iodine in a glass container with a lid and place a pitched glass container without a lid on it. It is left for a predetermined time in a furnace heated to a predetermined temperature. This treatment causes iodine to be adsorbed on the pitch, the amount of which is shown as an increase in weight. This amount of adsorption varies depending on the type of pitch, softening point and grain size, but is in the range of about 80-250%. If it is less than this amount, it will melt during the next heat treatment,
It becomes a lump. Also, when the number of particles increases, the entire particles harden and do not become hollow bodies.

The pitch thus iodine-treated is heat-treated at a temperature of at least the softening point of the pitch. Heat treatment is preferably performed at a temperature of 400 ° C. or higher. The minimum temperature for forming a hollow sphere seems to be affected by the heating rate. That is, a low temperature rise requires a low temperature and a rapid temperature rise requires a high temperature. Furthermore, most of the iodine adsorbed by this heat treatment is discharged as gas,
Can be collected. Further, in order to collect the adsorbed iodine, the heat treatment may be performed after the iodine is removed from the pitch subjected to the iodine treatment by the pretreatment in advance. In this case, the iodine-treated pitch is heated under normal pressure or reduced pressure at a temperature not higher than the softening point of the pitch, or is put in an organic solvent such as a lower alcohol which is a good solvent for iodine, or water to be dissolved. The pretreatment for removing the iodine does not affect the hollowing.

In the hollow spheres thus obtained, those having a heat treatment temperature of about 500 ° C. or lower are hydrocarbons containing hydrogen. In order to turn this into carbon, it is necessary to heat it to 800 ° C. or higher, and further it becomes a graphite spherical body by a heat treatment at 2000 ° C. or higher. There is no particular change in shape due to this heat treatment. In the case of a carbon material, what is calcined at a temperature of about 1500 ° C. or lower is called carbonaceous matter, and that which is calcined at about 2000 ° C. or higher is called graphite. In the present invention, hollow spheres composed of hydrocarbons are referred to as graphite. The quality up to that point is collectively called carbonaceous.

The hollow carbonaceous spheres obtained were slightly larger than the grain size of the pitch used, and the packing density obtained from the weight and the volume when the packing was closest packed was 0.3-0.6.
(G / cm ³ ). The organization of the walls of this spheroid is the same as that of the pitch. That is, a pitch containing an optically anisotropic carbonaceous mesophase (mesoface pitch) is an anisotropic structure in which carbon layer surfaces are arranged parallel to the surface of a sphere, and an optically isotropic pitch is used. If it is present, it becomes an optically isotropic tissue that does not show a particularly clear arrangement. Therefore, that of the hollow sphere can be determined by the structure of the pitch.

[0012]

EXAMPLES The method of the present invention will be described in more detail below with reference to examples.

Example 1 300 g of quinoline-soluble Coulter pitch from which free carbon was removed as a quinoline-insoluble component was placed in a 500-ml three-necked cylindrical flask. A glass tube reaching the bottom of the flask was inserted into the central hole, and a thermometer and a decomposition product distillation tube were attached to the side hole. Heat treatment was carried out at 430 ° C. for 30 minutes while blowing 2 L of nitrogen gas per minute from the tube having the central hole. The obtained pitch had a softening point of 231 ° C. and was optically isotropic from the observation of the structure with a polarization microscope. This pitch was crushed and sieved to 1.19-0.71 mm (hereinafter, this grain size is represented by grain size A), 0.71-0.25 mm (same grain size B), 0.25-0.105 mm. (Same grain size C), 0.1
05-0.053mm (same particle size D) and 0.053m
It was divided into m or less (same particle size E).

1 g of these pitch particles was placed in a glass bottle having an inner diameter of 20 mm and a height of 50 mm. Place a glass bottle with a pitch and without a lid in a glass reagent bottle with an internal volume of 500 ml containing iodine powder, put the lid on the reagent bottle, and then put it in a constant temperature oven preheated to 120 ° C., 1-8 Time processed. During the process, the bottle containing the pitch was sometimes vibrated to stir the pitch. Put the iodine-treated pitch in a magnetic dish and in a tubular furnace, while flowing nitrogen gas, 1 per minute
It was heated to 1000 ° C. at a temperature rising rate of 0 ° C. and kept for 30 minutes for heat treatment. The shape of the thus-obtained material was observed with a scanning electron microscope (SEM), embedded in a resin and polished, and the cross section was observed with a microscope. Furthermore, 5
1 g of carbonized product was placed in a ml volumetric flask, and the volume was measured from the height to obtain the packing density. The obtained results are summarized in Table 1. The yield of carbonization is the ratio to the raw material pitch. In addition, Experiment No. 1, 2, 3, 9, 1 in Table 1
0 and 12 are comparative examples.

[0015]

[Table 1]

The sphere was spherical when observed with a scanning electron microscope (SEM), and when the sphere was embedded in resin and polished, and then observed with a reflection polarization microscope, the wall thickness was about 30 μm. And the organization was isotropic.

Example 2 The coal tar pitch used in Example 1 was heat-treated in the same manner as in Example 1 at 430 ° C. for 120 minutes. The obtained pitch had a softening point of 288 ° C., and from the observation of its structure, it was mostly optical anisotropy, and the amount of anisotropy was 98%. The pitch was crushed, treated with iodine in the same manner as in Example 1, and then carbonized at 1000 ° C. The shape and packing density of the carbonized product thus obtained are summarized in Table 2. Experiment Nos. 16-19, 23, 25, 30, 33 and 36 of Table 2
Is a comparative example.

[0018]

[Table 2]

When the shape of these spherical objects was observed by SEM, they were spherical. As a typical example, the spherical body of Experiment No. 27 in Table 2 is shown in FIG. Also, when this was embedded in resin, polished, and observed with a reflection polarization microscope,
As shown in Fig. 2, it is hollow and the wall thickness is about 40μ.
m and the texture was optical anisotropy with the carbon layer planes arranged parallel to the walls.

Example 3 The pitch grain size B (0.25- used in Examples 1 and 2)
0.71 mm) is 120 at the pitch of Example 1.
It was treated in iodine vapor for 3 hours at 120 ° C. for 1 hour at the pitch of Example 2. Next, decompression treatment and ethanol extraction treatment were performed to recover the adsorbed iodine. The depressurization treatment was performed under a reduced pressure of 0.1 Torr at 50 ° C. for 15 hours. For the ethanol extraction treatment, put the iodine-treated pitch in about 200 times the volume of ethanol and stir it with stirring.
After standing at ℃ for 20 hours, filter with a glass filter,
It was washed with ethanol until it was not colored, and then dried.
These pitch powders were treated with 1000 in the same manner as in Example 1.
Heat treatment was performed at 30 ° C. for 30 minutes. The results obtained are summarized in Table 3
Shown in. The yield is the ratio to the raw material pitch used. The shape and structure of the heat-treated product were examined with an SEM and a reflection polarization microscope, and it was the same as when the iodine recovery treatment was not performed.

Further, the pitch degassed under reduced pressure was heat-treated while changing the heating rate and the maximum temperature, and then the packing density was measured. The results obtained are summarized in Table 4,
The yield is a ratio with respect to the raw material pitch used. The experiments Nos. 41, 44, 45, 47, 48 and 52 in Table 4 are comparative examples.

[0022]

[Table 4]

From the results shown in Table 4, it is understood that in order to obtain spherical bodies having a low packing density, it is necessary to perform heat treatment at a slow heating rate at 400 ° C. or higher, or to raise the temperature for rapid heating. Furthermore, elemental analysis of the spherical body of Experiment No. 50 obtained at 400 ° C. showed that the carbon content was 94.3%, the hydrogen content was 2.3%, and the nitrogen content was 0.3%. It was a hydrocarbon.

Furthermore, after the degassing treatment in Table 3, the spherical particles (experiment No. 37, 39) heat-treated at 1000 ° C. were placed in a Tammann furnace in an argon gas stream at 1500, 2000 and 2800 ° C.
And held for 60 minutes for processing. The shape of the obtained spherical body was observed by SEM and the structure was observed by a reflection polarization microscope.
It was almost the same as that of the treatment at 00 ° C. Table 5 shows the yield and packing density. The yield is the ratio to the raw material pitch.

[0025]

[Table 5]

Comparative Example 1 300 g of coal tar pitch having a softening point of 77 ° C. is 500 m
It was put in a cylindrical flask of 1 l and heat-treated at 430 ° C. for 3.5 hours while stirring in a nitrogen gas stream to obtain a pitch having a softening point of 368 ° C. The pitch was crushed to 0.25 to 0.71 mm and treated in iodine vapor at 80 ° C. for 1 hour. The yield of this product was 160.6 (wt%). When this was heat-treated at a temperature rising rate of 10 ° C / min to 1000 ° C, a carbon powder whose shape did not change was obtained. Therefore, 80 ℃
The iodine treatment time was 10 and 30 minutes, and yields of 121.3 and 142.6 wt% iodine-treated products were obtained. This was heat-treated to 1000 ° C. in the same manner as above, but it was also infusible.

Example 4 Naphtha tar pitch, which is a heavy oil by-produced during ethylene production by thermal decomposition of naphtha, and fluid catalytic cracking method (F
FCC decant oil produced as a by-product in the CC method) was used as a starting material. Add these ingredients to a 500 ml cylindrical flask.
0 g was added, and naphtha tar pitch was heat-treated at 430 ° C. for 60 minutes, and FCC decant oil was heat-treated at 460 ° C. for 120 minutes. The softening point of the obtained pitch was 218 ° C. for naphthatar pitch and 203 ° C. for FCC decant oil. After crushing these pitches to 0.25 to 0.71 mm and treating them in iodine vapor in the same manner as in Example 1,
Heat treatment was performed up to 1000 ° C. at a heating rate of 10 ° C./min.
The obtained results are summarized in Table 6. The experiments in Table 6
Nos. 55, 58 and 62 are comparative examples.

[0028]

[Table 6]

Comparative Example 2 300 g of asphalt, which is a residual oil of vacuum distillation of petroleum, was added to 5 parts.
It was put in a 00 ml cylindrical flask and heat-treated at 420 ° C. for 15 minutes to obtain a pitch having a softening point of 137 ° C. The pitch was crushed to 0.71-0.25 mm and treated with iodine in the same manner as in Example 1. When iodine treatment was performed at 80 ° C., the shape of the particles was 1 and 3 hours, but the particles were fused to each other in the treatment for 5 hours and melted to such an extent that the shape of the particles could not be retained in the treatment for 8 hours. At 100 ° C., it was already in a molten state after 1 hour of treatment. What was treated at 80 ° C. for 3 hours while maintaining the shape of the particles was heat-treated at 1000 ° C. to be melted to form a lumpy foam.

Example 5 300 g of the same asphalt used in Comparative Example 1 was added to 500
It was put in a ml cylindrical flask and heat-treated at 420 ° C. for 45 minutes. The softening point of the obtained pitch was 209 ° C. This pitch was crushed to 0.71-0.25 mm, and
Iodine was treated in the same manner as in. Then, it was fired up to 1000 ° C. and the condition of the product was examined. The results obtained are shown in Table 7. Experiment Nos. 63 and 66 in Table 7 are comparative examples.

[0031]

[Table 7]

[0032]

EFFECT OF THE INVENTION Hollow carbonaceous spheres can be produced by a simple operation of adsorbing iodine on pitch powder and making it hollow by heat treatment. The reason is presumed to be as follows. That is, iodine has the effect of converting pitch from thermoplasticity to thermosetting, as seen in the infusibilizing treatment of pitch fibers. When this effect is applied to pitch particles, it is presumed that hardening starts from the particle surface. It is considered that when the pitch particles, which are hardened only near the surface of the particles, are heated, the inside melts and decomposes, and the gas generated thereby causes foaming.

The features of the method of the present invention are listed below. (1) Any kind of pitch is acceptable as long as it has a softening point of about 150 to 300 ° C. (2) The objective can be achieved by the simple operation of performing iodine treatment at a relatively low temperature of 80-130 ° C.
Most iodine can be recovered. (3) The heat treatment of the iodine treatment, which is a foaming operation, is also about 400 ° C.
And relatively low temperature. This means that the obtained hollow spheres are still hydrocarbons and therefore have various chemical reactivities. Therefore, surface modification is possible.

The hollow carbonaceous spheres obtained according to the present invention can be used as a lightweight filler or a hollow activated carbon by activation as in the case of conventional carbon hollow spheres. Also, 400-
Since hydrocarbons hollowed out at 500 ° C are hydrocarbons, it is possible to manufacture lightweight exchangers by introducing ion-exchange groups, etc., and when sulfone groups are introduced as exchange groups, this is heat-treated at 800-1000 ° C. By doing so, the sulfone group is decomposed to become a sulfo group, which has excellent wettability with water, so that the hydrophobic surface of carbon can be modified.

[Brief description of drawings]

FIG. 1 is a scanning electron micrograph (100 ×) of a spherical body obtained in Example 2 and Experiment No. 27.

FIG. 2 is a reflection micrograph (250 times) of a cross section of a spherical body obtained in Example 2 and Experiment No. 27.

[Table 3]

Claims (1)

[Claims] 1. A softening point of 150-300 ° C., 0.05-1
After processing the pitch powder having a size of mm in iodine vapor at 80-130 ° C. so that the iodine adsorption amount represented by the weight increase amount is in the range of 80-250% by weight, 400
A method for producing a hollow carbonaceous sphere, which comprises performing a heat treatment at a temperature of ℃ or higher.