JP3143690B2 - Method for producing metal-containing pitch for producing activated carbon fiber, method for producing activated carbon fiber, and activated carbon fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal-containing pitch for producing activated carbon fibers, a method for producing activated carbon fibers using the metal-containing pitch as a raw material, and activated carbon fibers having novel characteristics obtained by the method. About.

[0002]

^2. Description of the Related Art The pore volume of a currently used activated carbon having a specific surface area of about 800 m ² / g is 0.3 to 0.3 m ² / g.
0.35 ml / g, specific surface area of 1200 m ² / g
The pore volume in the case of about g is 0.65 to 0.7 ml / g.
It is about. On the other hand, in pitch-based activated carbon fiber,
The pore volume when the specific surface area is about 1500 m ² / g is
0.8 ml / g, specific surface area 2000 m ² / g
In this case, the pore volume is about 1.1 ml / g.

The inventors of the present invention have conducted various studies for improving the properties of pitch-based activated carbon, and some of the results have been disclosed in JP-A-3-265510 and JP-A-4-1241.
No. 05, JP-A-5-294607 and the like.

[0004] The inventors of the present invention have aimed mainly at further increasing the pore size and adsorption capacity of fibrous activated carbon,
The above research has been further advanced.

[0005] Conventional activated carbon is a micropore (diameter: 0,1).
8 to 2 nm) and sub-micropores (diameter: 0.8 nm)
Less) activated carbon. Mesopore (caliber: 2
In order to obtain activated carbon having a large adsorption capacity with a developed activated carbon of 50 nm), it is necessary to increase the specific surface area and also increase the maximum volume.

Accordingly, for example, an oxygen-containing gas is blown into a low softening point pitch to increase its softening point, and then a metal compound is mixed into a product (air blown pitch).
It has been proposed that the mixture of the air blown pitch and the spinning pitch be spun, infused, carbonized, and then activated to improve the carbonization yield in producing activated carbon fibers having a large pore volume. ing. However, in this method, since the metal compound is difficult to be uniformly dispersed in the low-melting pitch, the metal compound is not uniformly mixed in the mixed spinning raw material, and as a result, activated carbon fibers with stable quality cannot be obtained, Activated carbon having an average pore diameter in the mesopore region cannot be obtained.

[0007]

Accordingly, an object of the present invention is to provide a method for producing activated carbon fibers having a large pore diameter and a large pore volume.

[0008]

The inventor of the present invention has conducted further research on the background of the state of the art as described above.
The low-melting pitch and the metal compound are mixed in a liquid hydrocarbon, and then the liquid hydrocarbon is removed by distillation.When the obtained distillation pitch and spinning pitch are mixed, the metal compound is uniformly mixed in the mixture. Found to be dispersed.

[0009] The pitch mixture thus obtained is suitable as a raw material for producing activated carbon fibers. The activated carbon fibers obtained therefrom have a large specific surface area and a fine pore volume as compared with conventional products. At the same time, it was also found that it has a unique physical property of being extremely large.

[0010] Further, in a subsequent study, it is obtained by mixing a low melting point pitch and a metal compound in a liquid hydrocarbon, then removing the liquid hydrocarbon by distillation, and blowing an oxygen-containing gas into the obtained distillation pitch. It has been found that air blown pitch is also suitable as a raw material for producing activated carbon fibers, similarly to the mixed pitch.

Further, an air blown pitch obtained by mixing coal tar and a metal compound in a liquid hydrocarbon, removing the liquid hydrocarbon by distillation, and blowing an oxygen-containing gas into the obtained distillation pitch is also used. It was also found that, like the above-mentioned mixed pitch, it was suitable as a raw material for producing activated carbon fibers.

That is, the present invention provides the following method for producing a metal-containing pitch for producing activated carbon fiber, a method for producing activated carbon fiber, and activated carbon fiber: Mixing a low softening point pitch and a hydrocarbon solution of an organometallic compound, then distilling the mixture under reduced pressure to remove hydrocarbons, and then mixing the obtained distillation pitch with a high softening point pitch. A method for producing a metal-containing pitch for producing activated carbon fibers.

2. Activated carbon fiber production characterized by mixing a low softening point pitch with a hydrocarbon solution of an organometallic compound, then distilling the mixture under reduced pressure to remove hydrocarbons, and then blowing an oxygen-containing gas into the obtained distillation pitch. Of producing metal-containing pitch for use.

3. Mixing activated carbon fiber with a hydrocarbon solution of a coal tar and an organometallic compound, then distilling the mixture under reduced pressure to remove hydrocarbons, and then blowing an oxygen-containing gas into the obtained distillation product for producing activated carbon fiber. A method for producing a metal-containing pitch.

4. After spinning the metal-containing pitch obtained by any one of the above-mentioned items 1 to 3, the obtained pitch fiber is infusibilized, carbonized, and activated to produce activated carbon fiber. Method.

5. Specific surface area is 700-2000m ² / g
When the pore volume (y: ml / g) is taken on the vertical axis and the specific surface area (x: m ² / g) is taken on the horizontal axis,
Activated carbon fiber having a large specific surface area and a large pore volume, wherein x and y satisfy the following relational expression: y ≧ −a + bx + cx ² (where a = 0.3177, b = 9.68 × 10 ^-4 , c
= 2.49 × 10 ⁻⁸ ) Hereinafter, the inventions described in the above items 1 to 5 are referred to as first to fifth inventions of the present application, respectively, and these are collectively referred to simply as the present invention.

I. First invention of the present application The low softening point pitch used in the first invention of the present application refers to a pitch having a softening point of about 60 to 150 ° C., more preferably about 70 to 120 ° C. according to the Mettler method (ASTM). Any pitch, such as a system pitch and a component soluble in an organic solvent of these pitches, can be used.

The high softening point pitch refers to a pitch having a softening point of about 180 to 330 ° C., more preferably about 250 to 300 ° C. according to the Mettler method (ASTM). Pitches, and those of any origin such as organic solvent-soluble components of these pitches can be used.

The organometallic compounds used in the present invention include:
It is at least one of an yttrium compound, a titanium compound, a zirconium compound, a ytterbium compound, a samarium compound, and a neodymium compound.

Examples of the yttrium compound include yttrium acetylacetonate, triscyclopentadienyl yttrium, yttrium naphthoic acid, yttrium isopropoxide and the like.

Examples of the titanium compound include titanium oxoacetylacetonate.

Examples of the zirconium compound include zirconium acetylacetonate.

Examples of the ytterbium compound include ytterbium iodide, triscyclopentadienyl and the like.

Examples of the samarium compound include samarium isopropoxide and samarium acetylacetonate.

Examples of the neodymium compound include triscyclopentadienyl neodymium, neodymium acetylacetonate and the like.

As the organometallic compound, an yttrium compound, a titanium compound, a zirconium compound and the like are more preferable.

The liquid hydrocarbon used in mixing the low softening point pitch with the organometallic compound is not particularly limited, and includes those which can dissolve the organometallic compound. More specifically, quinoline, tetrahydrofuran , Dichloromethane, benzene, toluene, xylene and the like.

In the first invention of the present application, the low-melting pitch and the hydrocarbon solution of the organometallic compound are first uniformly mixed. Alternatively, the low melting point pitch and the organometallic compound may be uniformly mixed in a hydrocarbon. The amount of the organometallic compound is usually 0.3 to 15 based on the weight of the low-melting pitch.
% (As metal; the same applies hereinafter), more preferably 1 to
It is about 15%. When the amount of the organometallic compound is excessive, the spinnability of the spinning pitch decreases or the specific surface area does not increase upon activation, whereas when the amount is too small, the properties of the obtained activated carbon fiber Is not improved and is no different from that of ordinary activated carbon fiber.

Next, the mixture obtained as described above is distilled under reduced pressure. The conditions of the vacuum distillation are not particularly limited, but as an example, the pressure is 50 to 100 Torr and the temperature is about 200 ° C.

The distillation pitch obtained by the above-mentioned vacuum distillation is:
Although it may vary mainly depending on the properties of the initial low softening point pitch, it usually has a softening point of about 80 to 160 ° C., more preferably about 9 ° C.
It is about 0 to 140 ° C.

Then, the metal-containing spinning pitch is obtained by mixing the distillation pitch obtained above with the high softening point pitch.

The mixing ratio between the distillation pitch and the high softening point pitch can vary depending on the properties of the two pitches to be mixed, the properties required for the spinning pitch, and the like. , High softening point pitch 200-1
About 200 parts by weight (more preferably about 300 to 1000 parts by weight), and a softening point 25 of the spinning pitch (mixture).
At a temperature of about 0 to 330 ° C (more preferably about 210 to 300 ° C), the metal content is about 0.1 to 5% (more preferably about 0.3 to 1%).

II. Second invention of the present application In the second invention of the present application, after a mixture of a low softening point pitch and an organometallic compound is distilled under reduced pressure, an oxygen-containing gas is blown into the obtained distillation pitch for treatment to obtain an air blown pitch.

The low-melting pitch and the organometallic compound used are the same as in the first invention of the present application.
This is performed in the same manner as in the first invention of the present application.

In the second invention of the present application, the metal content in the mixture of the low softening point pitch and the organometallic compound is adjusted in advance so that the metal content in the air blown pitch becomes a predetermined value. The conditions for vacuum distillation of this mixture are as described in the first application of the present application.
Same as the invention.

Examples of the oxygen-containing gas for blowing in the distillation pitch include air, ozone-containing air, oxygen-enriched air, and oxygen. The blowing process is performed at a temperature of 250 to 500 ° C.
Degree (more preferably about 300 to 400 ° C.), gas blowing amount (as air) 0.1 to 1 per kg of pitch
About 0 l / min (more preferably about 0.2 to 5 l / min)
Under the conditions described above.

The metal-containing spinning pitch obtained by the second invention of the present application has a softening point of about 250 to 350 ° C. (more preferably 2 to 350 ° C.).
(About 70 to 300 ° C.), and the metal content is about 0.1 to 5% (more preferably about 0.3 to 1%).

III. Third invention of the present application In the third invention of the present application, coal tar and a hydrocarbon solution of an organometallic compound are uniformly mixed. Alternatively, the coal tar and the organometallic compound may be uniformly mixed in the hydrocarbon. The amount of the organic metal compound used is usually about 0.02 to 1% (as a metal; the same applies hereinafter) based on the weight of the coal tar.

Next, the mixture of coal tar and the organometallic compound is distilled under reduced pressure, and an oxygen-containing gas is blown into the obtained distillation pitch for treatment to obtain an air blown pitch (spinning pitch). The conditions for distillation under reduced pressure of the mixture of coal tar and the organometallic compound are the same as in the first invention of the present application.

The conditions for blowing the oxygen-containing gas into the distillation pitch are the same as in the second invention of the present application.

The metal-containing spinning pitch obtained by the third invention of the present application has a softening point of about 250 to 350 ° C. (more preferably, about 2 ° C.).
(About 70 to 300 ° C.), and the metal content is about 0.1 to 5% (more preferably about 0.3 to 1%).

IV. Fourth invention of the present application In the fourth invention of the present application, activated carbon fibers are produced by spinning, infusibilizing, carbonizing and activating the metal-containing spinning pitch obtained in the first to third inventions of the present application. Get.

The steps from the spinning of the pitch to the activation can be carried out according to a conventional method, and the conditions and the like are not particularly limited, but are usually as follows.

In the spinning step, the metal-containing pitch obtained in the first to third aspects of the present invention is melted at a temperature higher than the softening point, preferably about 30 to 100 ° C. higher than the softening point, A pitch fiber is obtained by spinning.

In the infusibilizing step, the pitch fiber is heated from a temperature lower than the softening temperature in an oxidizing atmosphere, for example, air, and is maintained at a temperature of up to 400 ° C. for a necessary time.

Carbonization is performed by heating the infusible pitch fiber in an atmosphere of an inert gas such as argon or nitrogen at 5 to 10 ° C.
After raising the temperature to a predetermined maximum temperature of about 800 to 1200 ° C. at a rate of about / min, the temperature is held at the maximum temperature for about 10 minutes at the maximum.

The activation treatment is performed at 800 to 1200 ° C. in an atmosphere of carbonized fiber such as steam, carbon dioxide, oxygen, a mixture thereof, or a gas obtained by diluting these with an inert gas such as nitrogen.
It is carried out by holding at a temperature of about 5 to 120 minutes.

V. Activated carbon fiber obtained by the fifth invention of the present application has a specific surface area of 70%.
It is in the range of about 0 to 2000 m ² / g, and its pore volume satisfies the following relational expression. That is, in the activated carbon fiber according to the present invention, assuming that the pore volume is y (ml / g) and the specific surface area is x (m ² / g), y ≧ −a + bx + cx ²
(A = 0.3177, b = 9.68 × 10 ⁻⁴ , c = 2.
49 × 10 ⁻⁸ , 700 ≦ x ≦ 2000), which is unique to conventional products.

FIG. 1 is a graph showing the relationship between the specific surface area and the pore volume of the activated carbon fiber according to the present invention and a commercially available activated carbon fiber. In FIG. 1, the black squares represent the results according to the present invention, and the black triangles represent the results for commercial products. Further, white square marks indicate the results of Comparative Example 1 of the present application.

The above relational expression was obtained by plotting the characteristics of the activated carbon fiber of the present invention as shown in FIG.

[0051]

According to the present invention, activated carbon fibers can be produced with a high activation yield.

The obtained activated carbon fiber has a very peculiar property that the pore radius is large and the pore volume is extremely large in a specific specific surface area range.

Therefore, the activated carbon fiber according to the present invention is extremely useful as an adsorbent for a substance having a large molecular diameter.

[0054]

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention.

Example 1 3.2% of quinoline-insoluble matter and 7.8% of toluene-insoluble matter
After removing water from the coal tar containing the quinoline, quinoline-insoluble matter was removed at 150 ° C. using a filter paper.

Next, the coal tar 110 after the filtration treatment
0 g was placed in a distillation flask, and after the inside of the flask was set to a nitrogen atmosphere, the coal tar was heated to 80 ° C.

Next, quinoline 10 prepared in advance is prepared.
100 ml of a solution of 4 g of yttrium acetylacetonate dihydrate ｛Y (CH ₃ COCHCOCH ₃ ) ₃ .2H ₂ O in 0 ml was gradually added dropwise to the coal tar in the flask and mixed for about 5 hours.

Next, the coal tar containing the yttrium compound obtained above was distilled under reduced pressure to obtain
The quinoline in the dropped solution and the light components in the coal tar were removed to obtain an intermediate pitch having a softening point of 90.9 ° C.

600 g of the obtained intermediate pitch was weighed into an autoclave having a capacity of 1 l, and the mixture was stirred at a reaction temperature of 330 ° C. and a normal pressure of the reaction pressure at a rate of 5 l / min. The reaction was performed to obtain a pitch for spinning containing yttrium.

The properties of the obtained spinning pitch are as follows: softening point =
264.1 ° C., quinoline-insoluble content = 20.4%, toluene-insoluble content = 74.1%, acetone-soluble content = 6.9%, indicating an optically isotropic structure.

The yttrium content in the pitch was measured by a wavelength-dispersive X-ray fluorescence analyzer.
0.3%.

Next, the above-mentioned pitch was charged into a batch type mono-hole spinner, and spun at a pitch melting temperature of 308 ° C., a nozzle diameter of 0.3 mm and a winding speed of 380 m / sec to obtain a pitch fiber. .

The obtained pitch fiber is heated from room temperature to 300 ° C. in air at a rate of 2 ° C./min.
The infusibilization treatment was performed by holding for 80 minutes.

Next, the infusibilized pitch fiber was heated from room temperature to 850 ° C. at a rate of 10 ° C./min in a nitrogen gas atmosphere, and when it reached 850 ° C., steam was blown to activate the fiber.

The relationship between the activation treatment time and the yield of the obtained activated carbon fiber was as follows.

Activation time (min) Activated carbon fiber yield (%) 90 26 The properties of the obtained activated carbon fiber are as shown in Table 1.

[0067]

[Table 1]

Example 2 An intermediate pitch having a softening point of 95.0 ° C. was obtained in the same manner as in Example 1 except that the amount of yttrium acetylacetonate dihydrate dissolved in 100 ml of quinoline was changed to 13 g.
This intermediate pitch was blown with air in the same manner as in Example 1 to obtain a spinning pitch.

The properties of the obtained pitch for spinning were as follows: softening point =
276.3 ° C., quinoline-insoluble matter = 21.5%, toluene-insoluble matter = 75.3%, acetone-soluble matter = 7.1%, indicating an optically isotropic structure. The yttrium content in this pitch was 1.0%.

Next, pitch fibers were formed in the same manner as in Example 1 using the above-mentioned spinning pitch, and were subjected to infusibilization, carbonization and activation treatments to obtain activated carbon fibers.

The relationship between the activation treatment time and the yield of the obtained activated carbon fiber was as follows.

Activation time (min) Activated carbon fiber yield (%) 30 53 908 The properties of the obtained activated carbon fiber are as shown in Table 2.

[0073]

[Table 2]

Comparative Example 1 Example 1 was repeated except that a quinoline solution of yttrium acetylacetonate dihydrate was not mixed with coal tar.
A spinning pitch was prepared in the same manner as described above.

The properties of the obtained pitch for spinning were as follows: softening point =
275.3 ° C., quinoline insoluble content = 20.0%, toluene insoluble content = 73.4%, acetone soluble content = 6.8%, indicating an optically isotropic structure.

Next, pitch fibers were formed in the same manner as in Example 1 using the above-mentioned spinning pitch, and were subjected to infusibilization, carbonization and activation treatments to obtain activated carbon fibers.

The relationship between the activation treatment time and the yield of the obtained activated carbon fiber was as follows.

Activation time (min) Activated carbon fiber yield (%) 45 59 60 50 The properties of the obtained activated carbon fiber were as shown in Table 3.

[0079]

[Table 3]

Example 3 100 g of coal tar pitch having a softening point of 90 ° C. and a low softening point was placed in a flask, and the inside of the flask was replaced with Ar. Then, 450 ml of quinoline was added, and the mixture was stirred for 2 hours.

Next, Y (aca) was added to 50 ml of quinoline.
with stirring, a solution of c) ₃ · 2H ₂ O 1.45g was dropped in an Ar gas stream, mixed and stirred mixture After completion of the dropwise addition 3 hours.

Then, the pitch containing the yttrium compound obtained above was distilled at a temperature of 200 ° C. and a pressure of 75 Torr to remove quinoline in the dropped solution and light components in the pitch to obtain an intermediate pitch. Was.

The obtained intermediate pitch was blown with air in the same manner as in Example 1 to obtain a spinning pitch, which was then spun, made infusible, and activated to obtain an activated carbon fiber.

The yttrium content in the spinning pitch was measured by a wavelength-dispersive X-ray fluorescence analyzer.
0.3%.

The relationship between the activation treatment time and the yield of the obtained activated carbon fiber was as follows.

Activation time (min) Activated carbon fiber yield (%) 30 40 40 25 45 17 The properties of the obtained activated carbon fiber are as shown in Table 4.

[0087]

[Table 4]

Example 4 100 g of coal tar pitch having a softening point of 90 ° C. and a low softening point was placed in a flask, the inside of the flask was replaced with Ar, 450 ml of quinoline was added, and the mixture was stirred for 2 hours.

Next, Y (aca) was added to 50 ml of quinoline.
with stirring, a solution of c) ₃ · 2H ₂ O 1.45g was dropped in an Ar gas stream, mixed and stirred mixture After completion of the dropwise addition 3 hours.

Next, the pitch containing the yttrium compound obtained above was distilled at a temperature of 200 ° C. and a pressure of 75 Torr to remove quinoline in the dropped solution and light components in the pitch to obtain an intermediate pitch. Was.

Next, 100 parts by weight of the obtained intermediate pitch and 200 parts by weight of a spinning pitch having a softening point of 290 ° C. were heated at a temperature of 3 ° C.
After uniformly stirring and mixing at 30 ° C., spinning was performed sequentially in the same manner as in Example 1 using the obtained mixing pitch, infused, and activated.

The relationship between the activation treatment time and the yield of the obtained activated carbon fiber was as follows.

Activation time (min) Activated carbon fiber yield (%) 90 20 The properties of the obtained activated carbon fiber were as shown in Table 5.

[0094]

[Table 5]

Example 5 A petroleum pitch (ethylene bottom oil) was filtered at 150 ° C. using a filter paper to remove solid components.

Next, the oil-based pitch 200
0 g was placed in a distillation flask, and the flask was heated to 80 ° C. after a nitrogen atmosphere was set in the flask.

Next, the previously prepared quinoline 10
100 ml of a solution of 6 g of yttrium acetylacetonate dihydrate ｛Y (CH ₃ COCHCOCH ₃ ) ₃ .2H ₂ O in 0 ml was gradually added dropwise to the petroleum pitch in the flask, and mixed for about 5 hours. .

Next, the petroleum pitch containing the yttrium compound obtained above was distilled under reduced pressure to obtain
The quinoline in the dropped solution and the light components in the pitch were removed to obtain an intermediate pitch having a softening point of 88.1 ° C.

600 g of the obtained intermediate pitch was weighed into an autoclave having a capacity of 1 liter, and the mixture was stirred at a reaction temperature of 330 ° C. and a normal pressure of the reaction pressure at a rate of 5 liter / min. The reaction was performed to obtain a pitch for spinning containing yttrium.

The properties of the obtained pitch for spinning were as follows: softening point =
280.7 ° C, quinoline-insoluble content = 20.5%, toluene-insoluble content = 24.7%, acetone-soluble content = 10.7%, indicating an optically isotropic structure.

The yttrium content in the pitch was measured by a wavelength-dispersive X-ray fluorescence analyzer.
0.29%.

Next, the above-mentioned pitch was charged into a batch type mono-hole spinner, and spun at a pitch melting temperature of 323 ° C., a nozzle diameter of 0.3 mm, and a winding speed of 360 m / sec to obtain a pitch fiber. .

The obtained pitch fiber was heated from room temperature to 300 ° C. in air at a rate of 2 ° C./min.
The infusibilization treatment was performed by holding for 80 minutes.

Next, the infusibilized pitch fiber was heated from room temperature to 850 ° C. at a rate of 10 ° C./min in a nitrogen gas atmosphere. When the temperature reached 850 ° C., steam was blown to activate the pitch fiber.

The relationship between the activation treatment time and the yield of the obtained activated carbon fiber was as follows.

Activation time (min) Activated carbon fiber yield (%) 45 41 The properties of the obtained activated carbon fiber were as shown in Table 6.

[0107]

[Table 6]

[Brief description of the drawings]

FIG. 1 is a graph showing the results of measuring the relationship between the specific surface area and the pore volume for activated carbon fibers according to the present invention and commercially available activated carbon fibers.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hisashi Tamai 5-5-15 Minami Funari, Naka-ku, Hiroshima City, Hiroshima Prefecture (72) Inventor Shigeji Mizutori 3-19-15, Shiroyamadai, Hashimoto City, Wakayama Prefecture (72) Inventor Takayoshi Kaneda 435-75 Shiba, Sakurai City, Nara Prefecture (72) Inventor, Masayuki Shinohara 11-249, Teradabayashi, Joyo City, Kyoto Prefecture No. 144 (56) References JP-A-5-139712 (JP, A) JP-A-5-302216 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C10C 3/06 C10C 1/16 C10C 3/02 D01F 9/12 D01F 9/145

Claims (4)

(57) [Claims] 1. A low softening point pitch and a hydrocarbon solution of an organometallic compound are mixed, and then the mixture is distilled under reduced pressure to remove hydrocarbons, and then the obtained distillation pitch and a high softening point pitch are mixed. A method for producing a metal-containing pitch for producing activated carbon fibers. 2. A method of mixing a low softening point pitch with a hydrocarbon solution of an organometallic compound, and then distilling the mixture under reduced pressure to remove hydrocarbons, and then blowing an oxygen-containing gas into the obtained distillation pitch. A method for producing a metal-containing pitch for producing activated carbon fibers. 3. A method of mixing a coal tar with a hydrocarbon solution of an organometallic compound, distilling the mixture under reduced pressure to remove hydrocarbons, and then blowing an oxygen-containing gas into the obtained distillation product. Of producing a metal-containing pitch for producing activated carbon fibers. 4. After spinning the metal-containing pitch obtained by the method according to claim 1, the obtained pitch fiber is infusibilized, carbonized and activated. Method for producing activated carbon fiber.