JP3367534B2 - High adsorptive carbon material and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a highly adsorptive carbon material and a method for producing the same. More specifically, the present invention relates to a carbon material having a large average pore radius and a large pore volume of 2.5 to 4.0 ml / g and an average pore radius of 21 to 40 Å and having excellent adsorption performance. The manufacturing method is related. Since the carbon material of the present invention has a large average pore radius and a large pore volume and is excellent in adsorption performance, it is particularly useful as activated carbon for adsorption of polymer substances and the like.

[0002]

2. Description of the Related Art Conventionally, commercially available activated carbon has been known as a carbon material having excellent adsorption performance, but in recent years, as a material having excellent high adsorption performance, activated carbon having a high specific surface area for activating a carbonaceous material with an alkali vapor has been known. And its manufacturing method is known. These are disclosed, for example, in Japanese Examined Patent Publication No. 62-61529, US Pat. No. 3,624,004 and US Pat. No. 3,642.
657, US Pat. No. 3,817,874, US Pat. No. 3
No. 833514, U.S. Pat. No. 4,082,694, JP-A-1-230414, JP-A-2-97414 and the like are proposed. Further, a method of activating a carbon particle by attaching a metal catalyst thereto is reported in JP-A-1-141814 and JP-A-1-141815.

The carbon material (activated carbon) obtained by the above-mentioned alkali vapor activation method has a pore volume of about 2.9 ml / g, and its average pore radius is about 12Å. It is a carbon material that occupies a large amount. Such a carbon material has a higher adsorption performance than ordinary activated carbon, but it is still insufficient as a highly adsorptive carbon material.

In such a method based on alkali vapor activation, it is necessary to add a large excess of alkali metal compound such as potassium hydroxide to the carbonaceous material, preferably twice or more. There is a problem that it causes corrosion, and the mixture of the carbonaceous raw material and the alkali metal compound sticks during firing and the fluidity is poor and the device is clogged. Further, since a large excess of alkali is used, it is necessary to recover and reuse the residual alkali from the economical point of view, and there is a drawback that the manufacturing process becomes complicated.

Further, in order to produce such a carbon material, a special raw material such as mesocarbon microbeads must be used, and there are restrictions on the raw material, and in addition, the raw material mesocarbon microbeads can be obtained. This is not an industrially advantageous method because it requires complicated manufacturing steps.

On the other hand, when petroleum coke, which is easily available, is used as a raw material, the pore volume is usually 1.8 ml / g, the average pore radius is about 11 Å, and the pore volume with an average pore radius of 20 Å or more is large. No carbon material can be obtained.

Further, Japanese Unexamined Patent Publication (Kokai) No. 1-141814 discloses that activated carbon having a high adsorption ability can be produced in a short activation time by a method of activating a metal catalyst by adhering it to carbon particles. However, the activated carbon obtained by such a method has no great difference in its adsorption capacity from that of known activated carbon for adsorption, and it cannot be said that it is sufficient as a highly adsorptive carbon material.

[0008]

In view of the above situation, the present invention uses a carbonaceous material, which is relatively inexpensive and easily available, as a raw material and has an extremely large average pore radius and pore volume. It is intended to provide an industrially advantageous manufacturing method that does not cause corrosion of a carbon material having excellent performance and a manufacturing apparatus.

[0009]

Means for Solving the Problems The present inventor has conducted a multifaceted study on a highly adsorptive carbon material having a large average pore radius and a large pore volume and excellent in adsorption performance, and as a result, was produced at a relatively low cost. The present invention has been made by discovering that a highly adsorptive carbon material that is unprecedented in the past can be obtained by adding a Group 8 metal compound to a known carbonaceous material to activate it.

That is, the present invention has a pore volume of 2.5 to
The present invention relates to a highly adsorptive carbon material having a pore size of 4.0 ml / g and an average pore radius of 21 to 40Å and a specific surface area of 1600 to 2500 m ² / g, and a method for producing the same.

The highly adsorbent carbon material of the present invention having the above-mentioned pore characteristics can be obtained by adding a Group 8 metal compound to a carbonaceous material having a specific surface area of at least 100 m ² / g and activating the carbonaceous material. it can.

The raw carbonaceous material in the present invention is required to have pores having a specific surface area of at least 100 m ² / g as described above. Such carbonaceous material used as a raw material in the present invention is coconut husk, wheat husk,
Activated carbon of plant type such as chaff, sawdust, wood, and pulp effluent, and heavy bituminous activated carbon such as coal, petroleum, cokes thereof, and pitch, which meet the above requirements. Can be used. The carbonaceous material used as these raw materials can be used in the form of powder, crushed particles, granules or cylinders.

The carbonaceous material used as a raw material has a particle size ranging from 1 to 300 mesh, and either coarse particles or fine particles can be used. The smaller the particle size, the longer the activation time. Can be shortened, which is preferable. However, even if the particle size is large, if the activation time is sufficiently long, the highly adsorptive carbon material of the present invention can be obtained.

The highly adsorptive carbon material of the present invention is the above carbonaceous material having a specific surface area of at least 100 m ² / g.
A group metal compound is added and subjected to activation treatment in an oxidizing gas atmosphere. In the present invention, the addition of the group 8 metal compound is a carbon having a target large average pore radius and pore volume. It is an indispensable process for obtaining materials.

Examples of the Group 8 metal compound in the present invention include oxides such as iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum, hydroxides, silicides, sulfides, nitrides, phosphides, Inorganic acid salts such as carbides, halides, sulfates, nitrates, phosphates and carbonates,
At least one selected from organic acid salts such as formate, acetate, benzoic acid, lactate, citric acid, oxalic acid, and complex compounds is used.

Examples of representative metal compounds include iron hydroxide, iron chloride, iron fluoride, iron bromide, iron iodide, iron perchlorate, iron sulfide, iron nitride, iron phosphide, iron carbide, Inorganic acid salts such as iron sulfate, iron nitrate, iron carbonate, iron phosphate, iron silicate, etc., organic acid salts such as iron acetate, ferric trihydroxide heptabenzoate, iron lactate, iron citrate, iron oxalate, etc. Hexacyanoferrate, tris (2,2′-bipyridine) iron salt, dicyanobis (2,2
′ -Bipyridine) iron salt, tris (1,10-phenanthroline) iron salt, dicyanobis (1,10-phenanthroline) iron salt, iron carbonyl, and other iron compounds,

Inorganic acid salts such as cobalt chloride, cobalt sulfate, cobalt nitrate, and cobalt carbonate, organic acid salts such as cobalt formate and cobalt acetate, hexafluorocobaltate salts, and tris (1,10-phenanthroline) cobalt salt complexes. Cobalt compounds such as compounds,

Complexes of inorganic acid salts such as nickel chloride, nickel sulfate, nickel nitrate and nickel carbonate, organic acid salts such as nickel formate and nickel acetate, trifluoronickelate salts, tris (1,10-phenanthroline) nickel salts and the like. Nickel compounds such as compounds,

Inorganic acid salts such as palladium chloride, palladium sulfate and palladium nitrate, organic acid salts such as palladium formate and palladium acetate, palladium compounds such as bis (ethylenediamine) palladium salt, bis (1,10-phenanthroline) palladium salt and the like. Is mentioned.

These metal compounds may be used in the form of powder or solution, but a solution state is preferred for uniform impregnation, and a water-soluble compound is preferably used since it is usually used as an aqueous solution. In the case of a water-insoluble Group 8 metal compound, it can be used by dissolving it in an acid.

The addition amount of these Group 8 metal compounds is generally 1: 0.001 to 1: 1 by weight ratio with respect to the carbonaceous material.
It is in the range of 1: 0.1, preferably 1: 0.01 to.
A range of 1: 0.09 is preferred. If the addition amount is less than the above range, a carbon material having a large pore volume and an average pore radius as in the present invention cannot be obtained even if sufficient activation treatment is performed. When a large amount exceeding the above range is added, the pore volume increases, but the carbon material is embrittled and the yield remarkably decreases, which is not preferable.

In the present invention, when the Group 8 metal compound is added to the raw material carbonaceous material, the inside of the pores of the raw material carbonaceous material are removed beforehand before the addition of the Group 8 metal compound to the raw material carbonaceous material. It is preferable to sufficiently remove the adsorbed substances, solute substances, and the like that exist in a vaporized state. As a method for removing this, a method by boiling or deaeration by vacuum is generally used. In the method by boiling, a predetermined amount, for example, 2 to 5 times the amount of water is added to the raw carbonaceous material and the mixture is boiled under stirring for 10 minutes to 3 hours, preferably 20 minutes to 2 hours.

After performing the above-mentioned pretreatment, a predetermined amount of the powder or aqueous solution of the Group VIII metal compound is added to the mixed solution being boiled to dissolve and mix, and the mixture is allowed to cool in the pores while stirring. The whole is uniformly impregnated.

The impregnation time differs depending on the mixing ratio of the carbonaceous material and water, or the amount and concentration of the metal compound added.
Although it cannot be determined at once, it is sufficient if the carbonaceous material is impregnated with the metal compound for a sufficient time. Usually 10
Minutes to 30 hours is sufficient, preferably 30 minutes to
The range is 24 hours.

Next, the mixed solution is filtered, washed with water, dried and then
A carbonaceous material impregnated with a group metal compound is obtained. The excess metal not impregnated in the carbonaceous material can be reused by circulating the filtrate. Further, after filtration, it is not always necessary to wash and dry with water or a solvent, and the product can be subjected to the next activation treatment step after filtration. Further, after impregnating the Group 8 metal compound, the compound may be dried without filtering.

The activation treatment in the present invention is carried out under heating in an oxidizing gas atmosphere. Examples of the oxidizing gas atmosphere used here include water vapor, carbon dioxide, air, oxygen, ozone, and nitrogen dioxide. If desired, these oxidizing gases may be used as a mixture with a combustion gas or an inert gas. Particularly, it is preferable to use water vapor, carbon dioxide, and a mixture of these gases with a combustion gas or an inert gas before use.

The heating temperature in the activation step is usually in the range of 500 ° C to 1200 ° C, preferably 7 ° C.
It is in the range of 00 ° C to 1100 ° C. Heating temperature is 50
When the temperature is lower than 0 ° C, even if sufficient activation treatment is carried out, it is not preferable because those having a desired pore volume cannot be obtained. Further, at a high temperature exceeding 1200 ° C., the activation yield decreases, which is not preferable.

The activation time is usually sufficient in the range of 30 minutes to 5 hours, but is preferably in the range of 1 to 4 hours.
When the activation time is shorter than 30 minutes, the obtained carbon material has a small pore volume and a carbon material having high adsorption performance cannot be obtained. Further, when the time is longer than 5 hours, the pore volume increases, but the activation yield decreases, which is not preferable in terms of production efficiency.

The activation treatment may be a static type, but it is preferably a system in which the mixture is heated uniformly, and is a mobile type, a rotary type, or a flow type, and the heating method is an internal heat type or an external heat type. Is good. The activation treatment may be carried out in a batch system, but it is industrially practical to carry out the activation process in a continuous system because the operability is easy particularly when the mixture has excellent fluidity.

After the activation, the product is washed and dried to obtain a product. According to the method of the present invention, since the carbon material in a state in which the shape of the raw material carbonaceous material used is maintained, the shape of the product can be arbitrarily returned by selecting the shape of the raw material to be used without necessarily molding. This is an industrially advantageous production method because it is possible.

In the method of the present invention, the pore volume and the pore radius are formed by activating the raw carbonaceous material with the Group 8 metal compound uniformly impregnated in the pores. Therefore, the metal mainly acts as a catalyst to promote the reaction between the raw material carbonaceous material and the oxidizing gas to form fine pores, and the fine pores formed are developed and fine pores are formed. It is thought to expand the volume.

In the highly adsorptive carbon material of the present invention, commercially available activated carbon mainly develops micropores having an average pore radius of 10 Å or less, whereas mesopores having a pore size of 21 Å or more are mainly present, so that the molecular size is large. It can be suitably used for adsorption separation of vitamin B ₁₂ , assible-90, etc., and adsorption removal of coloring components and COD source substances.

Further, it has a high activity for decomposing inorganic substances such as hydrogen peroxide and hydrazine or organic substances, and has a decomposing performance several tens of times that of commercially available activated carbon. Decomposition of other organic substances also shows high decomposition activity in the presence of an oxygen generator, and is effective in reducing COD in wastewater.

Besides, decomposition of ozone and NO _x , SO
₂ , Adsorption and removal of harmful substances such as CO and CO ₂ , Adsorption and recovery of dissolved metals, Occlusion of methane, Canister for adsorbing gasoline, Electric double layer type capacitor, Electrode of battery, Use for medicine, etc. You can

[0035]

EXAMPLES Next, the method of the present invention will be described more specifically by way of examples. For the physical properties of each carbon material, the adsorption / desorption isotherm by the N ₂ gas adsorption method at 77 ° K was obtained, and the BET specific surface area was BET within the range of P / P _O = 0.02-0.3.
It was determined by plotting (multipoint method). (Measured by Auto-Soave-6 manufactured by Yuasa Ionics)

Example 1 Commercially available activated carbon (specific surface area 140 m) having a size of 12 to 32 mesh as a raw material was put into a 500 ml Erlenmeyer flask.
10 g of ² / g) is taken, and 250 g of ion-exchanged water is put into this and boiled. _{Thereafter, Fe (NO 3) 3 ·} 9H 2
0.9 g of O was added and the mixture was cooled with stirring for 60 minutes. After cooling, the mixed solution was filtered, washed with water, and then dried at 110 ° C. for 2 hours under a vacuum dryer at 1 mmHg to obtain a carbonaceous material impregnated with an iron compound.

2 g of this carbonaceous material was charged into a quartz reaction tube and heated in a carbon dioxide stream at a heating rate of 25 ° C./min to 1000.
The mixture was heated to ° C and kept at the same temperature for 60 minutes for activation to obtain a highly adsorptive carbon material. The physical properties of the obtained carbon material are as follows: pore volume 3.8 ml / g, average pore radius 35Å, specific surface area 21
70 m ² / g, N ₂ adsorption gas amount 2455 cc / g.

[0038] Example 2 Fe (NO ₃₎ in place of _{3 · 9H 2 O, Co (} NO 3)
_{2 · 6H 2 O, Ni (} NO 3) 2 · 6H 2 O, Pd (N
A high adsorptive carbon material was obtained in the same manner as in Example 1 except that 0.50 g of O ₃ ) ₂ was used. The physical properties of the obtained carbon material are shown below.

[0039]

[Table 1]

[0040] Example ₃ Fe (NO 3) in place of _{3 · 9H 2 O, (COO} ) 2 F
e.2H ₂ O and (CH ₃ COO) ₂ Ni were added to 0.
A high adsorptive carbon material was obtained in the same manner as in Example 1 except that 6 g was used. The physical properties of the obtained carbon material are shown below.

[0041]

[Table 2]

[0042] Example _{4 Fe (NO 3) 3 ·} 9H 2 O and 0.01 g, 0.3 g,
A high adsorptive carbon material was obtained in the same manner as in Example 1 except that 0.6 g and 1.0 g were used. The physical properties of the obtained carbon material are shown below.

[0043]

[Table 3]

Comparative Example 1 A carbon material was obtained under the same activation conditions as in Example 1 except that the raw material used in Example 1 was treated untreated for 40 minutes. The obtained carbon material has a pore volume of 0.9 m
L / g, average pore radius 11Å, specific surface area 2060 m ² / g, and amount of adsorbed gas 599 cc / g.

Example 5 Using the carbon materials obtained in Example 1 and Comparative Example 1,
The adsorption performance of vitamin B ₁₂ was measured. 25 mg of carbon material in 100 ml of aqueous solution containing 300 ppm of vitamin B ₁₂
After shaking and shaking at 25 ° C for 24 hours, the residual concentration of vitamin B _{12 in} the solution was measured with a colorimeter (wavelength 330 nm, 1
0 mm quartz cell) was measured.

[0046]

[Table 4]

Comparative Example 2 A carbon material was obtained in the same manner as in Example 1 except that coconut husk charcoal having a specific surface area of 84 m ² / g was used as a raw material. The physical properties of the obtained carbon material are: pore volume 0.8 ml / g, average pore radius 12.5Å, specific surface area 1269 m ² / g, adsorbed gas amount 514 cc / g.

[0048] Comparative Example ₃ Fe (NO 3) in place of _{3 · 9H 2 O Mg (NO} 3) ·
A carbon material was obtained in the same manner as in Example 1 except that 1.0 g of 6H ₂ O was added. The physical properties of the obtained carbon material are a pore volume of 1.5 ml / g, an average pore radius of 13Å, a specific surface area of 2356 m ² / g, and an adsorbed gas amount of 980 cc / g. As a result, it is clear that the addition of a metal compound other than the Group 8 metal compound in the periodic table cannot provide the highly adsorbent carbon material of the present invention.

[0049]

As described above, by adding a Group 8 metal compound to a raw material carbonaceous material having pores having a specific surface area of 100 m ² / g or more and activating it, the pore volume and the average pore radius are A highly adsorptive carbon material having large pores and high adsorption performance can be obtained. The carbon material of the present invention is a highly adsorbent carbon material mainly composed of mesopore-sized pores, having a large pore volume and an average pore radius, and is excellent in the adsorption performance of a polymer substance. It is useful as a separating agent. Further, it has a high decomposition activity for inorganic compounds and organic compounds and is useful as a COD reduction catalyst. The carbon material of the present invention is industrially advantageous because it can be obtained in a large amount in a wide range because commercially available activated carbon can be used as a raw material carbonaceous material. No corrosion, good flowability,
Moreover, it is an industrially advantageous method because it is a very easy manufacturing method with few steps.

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Claims (4)

(57) [Claims] 1. A pore volume of 2.5 to 4.0 ml / g, an average pore radius of 21 to 40 Å, and a specific surface area of 1600.
A highly adsorptive carbon material having a value of 2,500 m ² / g. 2. A Group 8 metal compound is added to a carbonaceous material having pores having a specific surface area of at least 100 m ² / g in a weight ratio of 1: 0.001 to 1: 0.1 to perform oxidation. The method for producing a highly adsorptive carbon material according to claim 1, wherein the activation treatment is carried out at 500 to 1200 ° C. in a reactive gas atmosphere. 3. The method according to claim 2, wherein the Group 8 metal compound is an inorganic acid salt or an organic acid salt of iron or nickel. 4. The method according to claim 2, wherein the addition amount of the Group 8 metal compound to the carbonaceous material is in the range of 1: 0.01 to 0.1 by weight.