JP2012188310A - Porous carbon - Google Patents

Abstract

An object of the present invention is to provide porous carbon having a very high specific surface area even if it is crystalline carbon.
SOLUTION: Porous carbon having mesopores and a carbonaceous wall constituting the outline of the mesopores, and having a Bragg angle 2θ of 26. in an X-ray diffraction spectrum for CuKα rays (wavelength 1.541１．５). It has a peak at 45 °. The carbonaceous wall preferably has a three-dimensional network structure, and the specific surface area is preferably 200 m ² / g or more and 1500 m ² / g or less.
[Selection] Figure 5

Description

  The present invention relates to porous carbon, and more particularly to porous carbon having mesopores.

  Porous carbon can be produced by using cellulose such as wood pulp, sawdust, coconut husk, cottonseed husk and rice husk, starchy materials such as straw, straw and corn, plant raw materials such as lignin, coal and A method of carbonizing by heating in a non-oxidizing atmosphere using a mineral raw material such as tar or petroleum pitch, and a synthetic resin such as phenol resin or polyacrylonitrile as a raw material is well known. A method of activating carbonized products (activated carbon) by treatment with a chemical is also well known.

In recent years, activated carbon with a high specific surface area as high as 3000 m ² / g can be obtained by using potassium hydroxide as an effective drug, mixing it with an organic resin and heating it in a non-oxidizing atmosphere. Has been confirmed and attracts attention (see Patent Document 1 below).

  However, in this method, an activator more than 4 times the amount of the organic resin is required, so that although recovery and reuse of potassium is attempted, the recovery rate is low and the cost is high. In the heating process, the alkali metal volatilizes, contaminates or damages the furnace, and also causes erosion when used as various industrial materials. Furthermore, activated carbon treated with alkali metal compounds is flammable. Therefore, many problems remain in practical use on an industrial scale, such as high in flame resistance.

  In view of the above, the organic resin is mixed with at least one alkaline earth metal compound selected from the group consisting of alkaline earth metal oxides, hydroxides, carbonates, and organic acid salts. A method for producing activated carbon including a step of heating and firing in a non-oxidizing atmosphere has been proposed (see Patent Document 2 below).

  As described above, porous carbon is produced by various methods. In order to graphitize, it has been attempted to further heat-treat the porous carbon. However, when porous carbon is heat-treated, not only can it not be graphitized, but also the specific surface area becomes smaller, which is not the improvement of the expected properties, but worse than the original properties, and the desired properties cannot be obtained. Had.

JP-A-9-86914 JP 2006-062954 A

  Accordingly, an object of the present invention is to provide porous carbon having a very high specific surface area even if it is crystalline carbon.

In order to achieve the above object, the present invention provides a porous carbon having mesopores and a carbonaceous wall constituting the outline of the mesopores, in an X-ray diffraction spectrum for CuKα rays (wavelength 1.541１．５). And a peak at 26.45 ° of the Bragg angle 2θ.
If the X-ray diffraction spectrum has a peak at 26.45 ° with a Bragg angle 2θ, it can be said that the carbonaceous wall is graphitized. Moreover, since the mesopores are present, it is possible to suppress the specific surface area from being reduced. Thus, graphitization can be performed with a specific surface area being large to some extent, so that it can be used in various fields (for example, gas adsorbing materials, negative electrode materials for nonaqueous electrolyte batteries, electrode materials for capacitors, etc.). .

In addition, it is not necessary that all the parts of the carbonaceous wall are graphitized, and there may be amorphous parts that are not graphitized in part. In the porous carbon of the present invention, mesopores are essential, but micropores are not essential. Therefore, micropores may or may not exist.
Here, in this specification, those having a pore diameter of less than 2 nm are referred to as micropores, and those having a pore diameter of 2 to 50 nm are referred to as mesopores.

The carbonaceous wall preferably has a three-dimensional network structure.
If the carbonaceous wall has a three-dimensional network structure, the porous carbon of the present invention can be applied even when the use of the porous carbon requires elasticity. In addition, when the porous carbon of the present invention is used as a gas adsorbent, the gas adsorption brain is improved because the gas flow is not hindered. When used as a capacitor electrode material, the movement of lithium ions and the like is facilitated.

The specific surface area is desirably 200 m ² / g or more.
When the specific surface area is less than 200 m ² / g, there is a problem that the amount of pores formed is insufficient, the gas adsorption ability is lowered, and it is difficult to form a three-dimensional network structure. On the other hand, the specific surface area is desirably 1500 m ² / g or less. When the specific surface area exceeds 1500 m ² / g, the shape of the carbon wall may not be maintained.

The mesopores are preferably open pores and have a structure in which the pore portions are continuous.
If it is the said structure, when the porous carbon of this invention is used as a gas adsorbent, since the flow of gas becomes smooth, it becomes easier to supplement gas. Moreover, when using as a negative electrode material of a nonaqueous electrolyte battery or an electrode material of a capacitor, lithium ions move smoothly.

The mesopore capacity is desirably 0.2 ml / g or more.
This is because, if the mesopore capacity is less than 0.2 ml, the gas adsorption ability when the relative pressure is high is lowered.

The bulk density is preferably from 0.1 g / cc to 1.0 g / cc.
If the bulk density is less than 0.1 g / cc, the shape of the carbon wall may not be maintained. On the other hand, if the bulk density exceeds 1.0 g / cc or less, formation of mesopores is insufficient and gas adsorption There is a problem that the performance is lowered and it is difficult to form a three-dimensional network structure.

The carbonaceous wall preferably has a portion having a layered structure, and the specific resistance is preferably 1.0 × 10 ² Ω · cm or less.

  According to the present invention, even if it is graphitic carbon, there is an excellent effect that porous carbon having a very high specific surface area can be provided.

It is a figure which shows the manufacturing process of this invention, Comprising: The figure (a) is explanatory drawing which shows the state which mixed the polyamic acid resin and magnesium oxide, The figure (b) is explanatory drawing which shows the state which heat-processed the mixture, FIG. 3C is an explanatory view showing porous carbon. The STEM (scanning transmission electron microscope) photograph of this invention carbon A1. STEM photograph of reference carbon Y1. STEM photograph of comparative carbon Z1. X-ray diffraction diagram of carbon A1 of the present invention and comparative carbon Z1. The present invention carbon A1, graph showing a relationship between a relative pressure and _{N 2} adsorption amount of reference carbon Y1, Y2, and comparative carbon Z1. The graph which shows the relationship between the pore diameter of this invention carbon A1, and its ratio. The graph which shows the relationship between the pore diameter of reference carbon Y1, and its ratio. The graph which shows the relationship between the pore diameter of comparative carbon Z1, and its ratio.

Embodiments of the present invention will be described below.
The porous carbon of the present invention is obtained by wet mixing or dry mixing an organic resin with an oxide (template particle) in a solution or powder state, and carbonizing the mixture in a non-oxidizing atmosphere or a reduced pressure atmosphere, for example, at a temperature of 500 ° C. or higher. Then, the oxide is removed by washing treatment to produce amorphous porous carbon (carbonaceous fired body). Thereafter, the amorphous porous carbon is removed in a non-oxidizing atmosphere or a reduced pressure atmosphere. It can be obtained by heat treatment at a temperature above the temperature at which crystalline porous carbon crystallizes (for example, 2000 ° C.).
The amorphous porous carbon has a large number of mesopores having substantially the same size, and micropores are formed at positions facing the mesopores in the carbonaceous wall formed between the mesopores. It is preferable to have a structure as described above. In this heat treatment of amorphous porous carbon, a state where a large number of mesopores are present is maintained, and at least a part of the carbon portion (carbonaceous wall) forms a layered structure. Therefore, porous carbon with improved crystallinity is obtained by this heat treatment.

As the organic resin, a polyimide containing at least one or more nitrogen or fluorine atoms in the unit structure, or a resin having a carbonization yield of 40 wt% or more and 85 wt% or less, such as a phenol resin or pitch, is preferably used.
Here, the polyimide containing at least one nitrogen or fluorine atom in the unit structure can be obtained by polycondensation of an acid component and a diamine component. However, in this case, it is necessary that one or both of the acid component and the diamine component contain one or more nitrogen atoms or fluorine atoms.
Specifically, a polyamic acid film which is a polyimide precursor is formed, and the solvent is removed by heating to obtain a polyamic acid film. Next, a polyimide can be manufactured by thermally imidating the obtained polyamic acid film at 200 ° C. or higher.

  Examples of the diamine include 2,2-bis (4-aminophenyl) hexafluoropropane [2,2-Bis (4-aminophenyl) hexafluoropropane], 2,2-bis (trifluoromethyl) -benzidine [2,2 ′. -Bis (trifluoromethyl) -benzidine], 4,4'-diaminooctafluorobiphenyl, 3,3'-difluoro-4,4'-diaminodiphenylmethane, 3,3'-difluoro-4,4'-diaminodiphenyl ether, 3,3′-di (trifluoromethyl) -4,4′-diaminodiphenyl ether, 3,3′-difluoro-4,4′-diaminodiphenylpropane, 3,3′-difluoro-4,4′-diaminodiphenyl Hexafluoropropane, 3,3'- Fluoro-4,4′-diaminobenzophenone, 3,3 ′, 5,5′-tetrafluoro-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetra (trifluoromethyl) -4, 4'-diaminodiphenylmethane, 3,3 ', 5,5'-tetrafluoro-4,4'-diaminodiphenylpropane, 3,3', 5,5'-tetra (trifluoromethyl) -4,4'- Diaminodiphenylpropane, 3,3 ′, 5,5′-tetrafluoro-4,4-diaminodiphenylhexafluoropropane, 1,3-diamino-5- (perfluorononenyloxy) benzene, 1,3-diamino- 4-methyl-5- (perfluorononenyloxy) benzene, 1,3-diamino-4-methoxy-5- (perfluorononenyloxy) benzene, 1 3-diamino-2,4,6-trifluoro-5- (perfluorononenyloxy) benzene, 1,3-diamino-4-chloro-5- (perfluorononenyloxy) benzene, 1,3-diamino- 4-Pubromo-5- (perfluorononenyloxy) benzene, 1,2-diamino-4- (perfluorononenyloxy) benzene, 1,2-diamino-4-methyl-5- (perfluorononenyloxy) ) Benzene, 1,2-diamino-4-methoxy-5- (perfluorononenyloxy) benzene, 1,2-diamino-3,4,6-trifluoro-5- (perfluorononenyloxy) hensen, 1,2-diamino-4-chloro-5- (perfluorononenyloxy) benzene, 1,2-diamino-4-bromo-5- (perfluorononenyloxy) Xy) benzene, 1,4-diamino-3- (perfluorononenyloxy) benzene, 1,4-diamino-2-methyl-5- (perfluorononenyloxy) pencene, 1,4-diamino-2- Methoxy-5- (perfluorononenyloxy) benzene, 1,4-diamino-2,3,6-trifluoro-5- (perfluorononenyloxy) benzene, 1,4-diamino-2-chloro-5 -(Perfluorononenyloxy) benzene, 1,4-diamino-2-pbromo-5- (perfluorononenyloxy) benzene, 1,3-diamino-5- (perfluorohexenyloxy) benzene, 1,3 -Diamino-4-methyl-5- (perfluorohexenyloxy) benzene, 1,3-diamino-4-methoxy-5- (perfluorohexenyl) Xyl) benzene, 1,3-diamino-2,4,6-trifluoro-5- (perfluorohexenyloxy) benzene, 1,3-diamino-4-chloro-5- (perfluorohexenyloxy) benzene, 1 , 3-Diamino-4-bromo-5- (perfluorohexenyloxy) benzene, 1,2-diamino-4- (perfluorohexenyloxy) benzene, 1,2-diamino-4-methyl-5- (perfluoro Hexenyloxy) benzene, 1,2-diamino-4-methoxy-5- (perfluorohexenyloxy) benzene, 1,2-diamino-3,4,6-trifluoro-5- (perfluorohexenyloxy) benzene, 1,2-diamino-4-chloro-5- (perfluorohexenyloxy) benzene, 1,2-diamino-4- Lomo-5- (perfluorohexenyloxy) benzene, 1,4-diamino-3- (perfluorohexenyloxy) benzene, 1,4-diamino-2-methyl-5- (perfluorohexenyloxy) benzene, 1, 4-diamino-2-methoxy-5- (perfluorohexenyloxy) benzene, 1,4-diamino-2,3,6-trifluoro-5- (perfluorohexenyloxy) benzene, 1,4-diamino-2 -Chloro-5- (perfluorohexenyloxy) benzene, 1,4-diamino-2-promo-5- (perfluorohexenyloxy) benzene, p-phenylenediamine (PPD) containing no fluorine atom, dioxydianiline An aromatic diamine such as The diamine component may be used in combination of two or more of the above aromatic diamines.

On the other hand, the acid component includes 4,4-hexafluoroisopropylidenediphthalic anhydride (6FDA) containing a fluorine atom and 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride containing no fluorine atom. Product (BPDA), pyromellitic dianhydride (PMDA) and the like.
Examples of the organic solvent used as a solvent for the polyimide precursor include N-methyl-2-pyrrolidone and dimethylformamide.

The imidization method is shown in a known method (for example, see “New Polymer Experimental Science” edited by the Society of Polymer Science, Kyoritsu Shuppan, March 28, 1996, Volume 3, Synthesis and Reaction of Polymers (2), page 158). Thus, either heating or chemical imidization may be followed, and the present invention is not affected by this imidization method.
Furthermore, as resins other than polyimide, those having a carbon yield of 40% or more, such as petroleum tar pitch and acrylic resin, can be used.

On the other hand, in addition to alkaline earth metal oxides (magnesium oxide, calcium oxide, etc.), the raw material used as the oxide is a metal organic acid (magnesium citrate, Magnesium oxalate, calcium citrate, calcium oxalate, etc.) can also be used.
In addition, as the cleaning liquid for removing oxides, general inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, citric acid, acetic acid, and formic acid are used, and it is preferably used as a dilute acid of 2 mol / l or less. It is also possible to use hot water of 80 ° C. or higher.

  Further, the carbonization of the mixture is preferably performed at a temperature of 500 ° C. or higher and 1500 ° C. or lower in a non-oxidizing atmosphere or a reduced pressure atmosphere. Since the resin with a high carbon yield is a polymer, the carbonization may be insufficient at less than 500 ° C. and the pores may not be sufficiently developed. This is because coarsening causes the pore size to be reduced and the specific surface area to be reduced. The non-oxidizing atmosphere is an argon atmosphere or a nitrogen atmosphere, and the reduced pressure atmosphere is an atmosphere of 133 Pa (1 torr) or less.

  When heat-treating the amorphous porous carbon, it is necessary to perform in a non-oxidizing atmosphere or a reduced pressure atmosphere. In this case, the non-oxidizing atmosphere is an argon atmosphere or a nitrogen atmosphere, as described above. The reduced pressure atmosphere is an atmosphere of 133 Pa (1 torr) or less as described above. Furthermore, the heat treatment temperature is not a problem as long as it is higher than the temperature at which amorphous carbon crystallizes, but in order to crystallize smoothly and in a short time, it is preferably 800 ° C. or higher, and the temperature is 2000 ° C. or higher. desirable. However, if the excessive temperature is high, energy is wasted, so that the heat treatment temperature is preferably 2500 ° C. or less.

Example 1
First, as shown in FIG. 1A, a polyamic acid resin (imide-based resin) 1 as a carbon precursor and magnesium oxide (MgO, average crystallite diameter is 100 nm) 2 as a template particle are 90: Mix in a weight ratio of 10. Next, as shown in FIG.1 (b), this mixture was heat-processed at 1000 degreeC in nitrogen atmosphere for 1 hour, and the polyamic acid resin was thermally decomposed, and the baked product provided with the carbonaceous wall 3 was obtained. Next, as shown in FIG. 1 (c), the obtained fired product is washed with a sulfuric acid solution added at a rate of 1 mol / l to completely elute MgO, so that non-having many mesopores 4 are obtained. Crystalline porous carbon 5 was obtained. Finally, this amorphous porous carbon was heat-treated at 2500 ° C. for 1 hour in a nitrogen atmosphere to obtain porous carbon.
The porous carbon thus produced is hereinafter referred to as the present invention carbon A1.

  A STEM (scanning transmission electron microscope) photograph of the carbon A1 of the present invention is shown in FIG. As can be seen from FIG. 2, at least a part of the carbon part of the carbon A1 of the present invention is layered, and it can be seen that the crystallinity of at least a part of the carbon part is developed. That is, it can be seen that the carbon A1 of the present invention has developed the crystallinity of at least a part of the carbonaceous wall 3. In addition, since the interlayer distance between adjacent layers is about 0.33 nm, in the case of an 11-layer structure, the thickness of the carbon portion forming the layer shape is 3.3 nm (0.33 nm × [11-1]). Further, it is recognized that the carbon A1 of the present invention has a three-dimensional network structure (sponge-like carbon shape), and the mesopores are open pores, and the pore portions are continuous. It was.

(Reference Example 1)
Porous carbon was produced in the same manner as in Example 1 except that the temperature when the amorphous porous carbon was heat-treated was 2000 ° C.
The porous carbon thus produced is hereinafter referred to as reference carbon Y1.
A STEM photograph of the reference carbon Y1 is shown in FIG. As is apparent from FIG. 3, it can be seen that at least a part of the carbon part of the reference carbon Y1 is layered, and thus at least a part of the carbon part is crystallized to have graphite characteristics. Further, it was recognized that the reference carbon Y1 has a three-dimensional network structure (sponge-like carbon shape), and the mesopores are open pores and the pore portions are continuous. .

(Reference Example 2)
Porous carbon was produced in the same manner as in Example 1 except that the temperature during heat treatment of amorphous porous carbon was 1400 ° C.
The porous carbon thus produced is hereinafter referred to as reference carbon Y2.
Although not shown, when the reference carbon Y2 was examined by STEM, it was found that the carbon portion was not layered and therefore the carbon portion was present in an amorphous state.

(Comparative Example 1)
Porous carbon was produced in the same manner as in Example 1 except that the temperature when the amorphous porous carbon was heat-treated was 900 ° C.
The porous carbon thus produced is hereinafter referred to as comparative carbon Z1.
A STEM (scanning transmission electron microscope) photograph of the comparative carbon Z1 is shown in FIG. As can be seen from FIG. 4, at least a part of the carbon part of the comparative carbon Z1 has a layered structure, and it can be seen that the crystallinity of at least a part of the carbon part is developed. Further, it was confirmed that the comparative carbon Z1 has a three-dimensional network structure (sponge-like carbon shape), and the mesopores are open pores, and the pore portions are continuous. .

(Reference Example 3)
The same as in Example 1 except that activated carbon (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of amorphous porous carbon as the carbon material before the heat treatment, and the activated carbon was heat treated at 2000 ° C. Thus, porous carbon was produced.
The porous carbon thus produced is hereinafter referred to as reference carbon Y3.

(Reference Example 4)
Example 1 except that activated carbon (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of amorphous porous carbon as the carbon material before the heat treatment, and the activated carbon was heat treated at 1400 ° C. Thus, porous carbon was produced.
The porous carbon thus produced is hereinafter referred to as reference carbon Y4.

(Reference Example 5)
The same as in Example 1 except that activated carbon (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of amorphous porous carbon as the carbon material before the heat treatment, and that the activated carbon was not heat treated. Thus, porous carbon was produced.
The porous carbon thus produced is hereinafter referred to as reference carbon Y5.

(Experiment 1)
Since X-ray diffraction (the source is CuKα) of the carbon A1 of the present invention and the comparative carbon Z1 was performed, the result is shown in FIG.
As is clear from FIG. 5, in the carbon A1 of the present invention, the graphite peak (002 plane) is noticeable at the Bragg angle (2θ ± 0.2 °) = 26.45 °, whereas the comparative carbon In Z1, it is recognized that no graphite peak (002 plane) is observed at a Bragg angle of 26.45 °. Therefore, it can be seen that carbon is graphitized in the present carbon A1, but carbon is not graphitized in the comparative carbon Z1.
When the crystallite size was determined from the half-value width of the peak of the X-ray diffraction result using the Scherrer equation, the crystallite diameter was about 30 nm.

(Experiment 2)
Since the relationship between the pressure in the carbon A1 of the present invention, the comparative carbon Z1, and the reference carbons Y1 and Y2 and the N ₂ adsorption amount was examined, the results are shown in FIG. The experimental method was measured by a nitrogen adsorption method using a specific surface area measuring device (Bellsorp 18, Nippon Bell Co., Ltd.). About 0.1 g of a sample was collected in a cell and measured after degassing at 300 ° C. for about 5 hours in the sample pretreatment section of the apparatus.

As is clear from FIG. 6, in the relative pressure range of 0 to 0.1, the reference carbon Y2 and the comparative carbon Z1 have increased N ₂ gas adsorption, whereas the reference carbon Y1 has a reference carbon. It can be seen that the amount of N ₂ gas adsorbed is smaller than that of Y2 and comparative carbon Z1, and that the carbon A1 of the present invention hardly adsorbs N ₂ gas. On the other hand, in the range where the relative pressure exceeds 0.1, the carbon A1 of the present invention and the reference carbon Y1 are less adsorbed with N ₂ gas than the reference carbon Y2 and the comparative carbon Z1, but sufficiently adsorb N ₂ gas. It is recognized that In order to investigate the reason for such an experimental result, the following Experiment 3 was performed.

(Experiment 3)
The BET specific surface area, mesopore capacity, and micropore capacity in the present invention carbon A1, comparative carbon Z1, and reference carbons Y1 and Y2 were examined, and the results are shown in Table 1. The BET specific surface area was calculated from the adsorption isotherm using the BET method. The mesopore capacity was examined by the BJH (Berret-Joyner-Halenda) method. Furthermore, the micropore volume was examined by the HK (Horbath-Kawazoe) method.

  As is apparent from Table 1, porous carbon is used as the carbon material before the heat treatment, and the reference carbon Y2 and the comparative carbon Z1 heat-treated at 900 ° C. or 1400 ° C. have high gas adsorbing ability when the relative pressure is high. Both the mesopores and the micropores having high gas adsorbing ability when the relative pressure is low at a position facing the mesopores are large. Therefore, the reference carbon Y2 and the comparative carbon Z1 have a high gas adsorption capacity regardless of the relative pressure.

On the other hand, in the reference carbon Y1 using porous carbon as the carbon material before heat treatment and heat-treated at 2000 ° C., the capacity of mesopores and micropores is slightly larger than that of the reference carbon Y2 and the comparative carbon Z1. Since it is small, the gas adsorption capacity is slightly lowered regardless of the relative pressure. Further, in the carbon A1 of the present invention in which porous carbon is used as a carbon material before heat treatment and heat-treated at 2500 ° C., mesopores and micropores are not only compared with the reference carbon Y1 but also the reference carbon Y1. The capacity with the micropores is particularly small. Therefore, regardless of the relative pressure level, the gas adsorbing ability is lowered, and in particular, since the capacity of the micropores is remarkably reduced, the gas adsorbing ability is particularly lowered when the relative pressure is low.
Furthermore, when the reference carbons Y3 and Y4 are compared with the reference carbon Y5, it can be seen that the micropores are significantly reduced by the heat treatment. On the other hand, if reference carbons Y1, Y2 and comparative carbon Z1 are compared, it can be seen that the presence of mesopores suppresses the reduction of micropores even when the heat treatment temperature rises. . However, in the carbon A1 of the present invention in which the heat treatment temperature is increased to 2500 ° C., a decrease in micropores is observed.
For the above reason, it is considered that the result as shown in Experiment 2 was obtained.

As described above, the carbon A1 of the present invention and the reference carbon Y1 have lower gas adsorbing ability than the reference carbon Y2 and the comparative carbon Z1, but activated carbon is used as a carbon material before heat treatment, which is a gas compared to the case of heat treatment. The adsorptive capacity is considered to be much higher. This is because the capacity of the mesopores and micropores is extremely small in the reference carbon Y3 obtained by heat treatment at 2000 ° C. using activated carbon as the carbon material before the heat treatment, and thus the gas adsorption capacity is considered to be remarkably lowered. is there.
From the above, in the carbon A1 of the present invention and the reference carbon Y1, the porous state is maintained by having mesopores even though at least part of the carbon is crystallized. It is considered that the advantages of carbon such as can be fully exhibited.

  In the reference carbon Y1, the BET specific surface area is also slightly smaller because the capacity of mesopores and micropores is slightly smaller than that of the reference carbon Y2 and the comparative carbon Z1. In the carbon A1 of the present invention, since the capacity of mesopores and micropores is further reduced, the BET specific surface area is further reduced. However, the carbon A1 of the present invention and the reference carbon Y1 have a significantly larger BET specific surface area than the reference carbon Y3 having extremely small mesopore and micropore capacities.

  In addition, in order to improve gas adsorption capacity, etc., it is desirable that the mesopore capacity is large, but it is not limited to 0.55 ml / g or more of the carbon A1 of the present invention, but 0.2 ml / g or more. If it is good. In addition, it is thought that such a small mesopore capacity is obtained when the porous carbon is heat-treated at a temperature exceeding 2500 ° C.

(Experiment 4)
Since the bulk density of the present invention carbon A1, reference carbon Y1, and comparative carbon Z1 was examined, the results are shown in Table 2.

  As is clear from Table 2, it is recognized that the carbon A1 of the present invention and the reference carbon Y1 have a larger bulk density than the comparative carbon Z1, and in particular, the bulk density of the carbon A1 of the present invention is large. It is recognized that As described above, the carbon A1 of the present invention and the reference carbon Y1 have smaller mesopore and micropore capacities than the comparative carbon Z1 (the volume of the carbon portion is increased). In this case, it is considered that the capacity of mesopores and micropores is very small.

(Experiment 5)
Since the pore size distribution (mesopore size distribution) of the inventive carbon A1, reference carbon Y1 and comparative carbon Z1 was examined by the BJH method, the results are shown in FIGS. 7 to 9 (FIG. 7 shows the inventive carbon A1, FIG. 8). Indicates reference carbon Y1, and FIG. 9 shows comparative carbon Z1).
As apparent from FIGS. 7 to 9, the mesopore size peak in the present invention carbon A1, the reference carbon Y1 and the comparative carbon Z1 is 3 to 5 nm. Therefore, the mesopore size varies depending on the heat treatment temperature. It can be seen that the peak does not change.

(Experiment 6)
The specific resistances of the carbon A1 of the present invention, the comparative carbon Z1, and the reference carbon Y1 to the reference carbon Y5 were examined, and the results are shown in Table 3. In the experiment, acetone as a solvent was added to a material obtained by physically mixing each carbon and polytetrafluoroethylene (Teflon (registered trademark) 6J, manufactured by DuPont) at a weight ratio of 80:20. And processed into a sheet. In order to dry the solvent, a sheet of 100 mm × 100 mm × 1 mm was prepared by drying at 120 ° C. for 5 hours. And the specific resistance of this sheet | seat was measured using the four probe method.

As is apparent from Table 3, the case where porous carbon is used as the carbon material before the heat treatment is considered. In the present carbon A1 and the reference carbon Y1 having a heat treatment temperature of 2000 ° C. or higher, the specific resistance is 2.0-3. Whereas it is 1 × 10 ¹ Ω · cm, the specific resistance is 1.0 × 10 ^{5 to 3.5} × 10 ⁵ Ω · cm for the reference carbon Y2 and the comparative carbon Z1 whose heat treatment temperature is less than 2000 ° C. It is recognized that Therefore, it can be seen that the specific resistance of the carbon A1 of the present invention and the reference carbon Y1 is significantly smaller than that of the reference carbon Y2 and the comparative carbon Z1.

On the other hand, considering the case where activated carbon is used as the carbon material before heat treatment, the reference carbon Y3 having a heat treatment temperature of 2000 ° C. or higher has a specific resistance of 8.0 × 10 ² Ω · cm, whereas the heat treatment temperature is It is recognized that the reference carbon Y4 and the reference carbon Y5 below 2000 ° C. have a specific resistance of 3.8 × 10 ^{4 to} 2.4 × 10 ⁵ Ω · cm. Therefore, the specific resistance of the reference carbon Y3 is smaller than that of the reference carbon Y4 and the reference carbon Y5. However, it can be seen that the specific resistance is larger than the carbon A1 of the present invention and the reference carbon Y1. The reason for this is not clear, but in the present carbon A1 and the reference carbon Y1, mesopores are sufficiently present and a layered structure is developed, whereas in the reference carbon Y3, there are almost no mesopores and the layered structure is almost developed. It is thought that it is caused by not doing.
The specific resistance is preferably as small as possible, but need not be 3.1 × 10 ¹ Ω · cm or less, and can be used in various fields as long as it is 1.0 × 10 ² Ω · cm or less. .

  The present invention can be used as a gas adsorbing material, a negative electrode material for a nonaqueous electrolyte battery, an electrode material for a capacitor, and the like.

1: Polyamic acid resin (imide resin)
2: Magnesium oxide 3: Carbonaceous wall 4: Mesopores 5: Porous carbon

Claims (8)

Porous carbon comprising mesopores and a carbonaceous wall constituting the outline of the mesopores,
A porous carbon characterized by having a peak at 26.45 ° of a Bragg angle 2θ in an X-ray diffraction spectrum for CuKα rays (wavelength 1.541１．５).   The porous carbon according to claim 1, wherein the carbonaceous wall has a three-dimensional network structure. The porous carbon of Claim 1 or 2 whose specific surface area is 200 m < ² > / g or more.   The porous carbon according to any one of claims 1 to 3, wherein the mesopores are open pores, and the pore portions are continuous.   The porous carbon according to any one of claims 1 to 4, wherein the mesopore has a capacity of 0.2 ml / g or more.   The porous carbon according to any one of claims 1 to 5, wherein the bulk density is 0.1 g / cc or more and 1.0 g / cc or less.   The porous carbon according to any one of claims 1 to 6, wherein a portion having a layered structure is present on the carbonaceous wall. The porous carbon according to any one of claims 1 to 7, wherein the specific resistance is 1.0 × 10 ² Ω · cm or less.