JP2011093774A - Activated carbon, process for producing the same, method of refining liquid using the same, and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an activated carbon that retains meso pores suitable for removing trace components in liquid, has a large specific surface area and a high bulk density, and is capable of effectively adsorbing and removing trace components in liquid such as hydrocarbon oil, and to provide a method for producing the same. <P>SOLUTION: The activated carbon has a specific surface area Sa of 800-4,000 m<SP>2</SP>/g, a total pore volume Va of 0.5-1.2 cm<SP>3</SP>/g, and an ash content of 3-10 mass%. The method for producing the activated carbon includes a step of carbonizing a raw material containing ≥40 mass% of chaffs and a step to activate the carbonized product. The method for producing the activated carbon may further include a step of removing ashes in the activated carbon with alkali treatment. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to activated carbon, a method for producing activated carbon, a liquid purification method, and a fuel cell system, and in particular, a liquid purification method using a specific activated carbon as an adsorbent, for example, adsorption removal of sulfur compounds from hydrocarbon oil. The present invention also relates to a purification method, and further to a fuel cell system using the purification method.

And CO ₂ gas as a greenhouse gas, from the viewpoint of reducing the emissions of automotive exhaust gases, such as NO _X, further reduction of sulfur content in the fuel, he is strongly desired by society. In Japan, sulfur has already been regulated to 10 mass ppm or less since 2007 for diesel and gasoline since 2008. On the other hand, recent technological innovations in fuel cells are remarkable. When the hydrogen source is determined for petroleum-based fuel, if the sulfur content in the fuel oil is not reduced to the ppb level, the fuel cell reformer and the electrode catalyst are poisoned by the sulfur content, and the fuel cell system Thus, the desired life is not obtained. Against this background, desulfurization technology for obtaining ultra-low sulfur petroleum fuel oil has been actively researched.

  Most of the difficult desulfurization compounds that are difficult to remove by conventional hydrodesulfurization methods are benzothiophenes and dibenzothiophenes. In the case of kerosene, the ratio of benzothiophenes is particularly large, and the ratio of benzothiophenes to the total sulfur compounds is often 70% or more as the sulfur content. However, dibenzothiophenes with a low content are more difficult to remove, and in particular, alkyl dibenzothiophenes having a large number of alkyl groups are very difficult to remove. On the other hand, there is a demand for a method that can be easily and efficiently desulfurized by a simple operation. For example, no reduction treatment or hydrogen is required, no pressure is required, and room temperature to about 150 ° C. Therefore, a desulfurization agent that can efficiently remove dibenzothiophenes at a relatively low temperature is desired. In order to use a large amount of a desulfurizing agent in a refinery or the like, not only the removal performance but also the cost and economy must be excellent.

  Activated carbon having a specific pore structure, particularly fibrous activated carbon, has been reported to have high removal performance with respect to dibenzothiophenes contained in light oil and kerosene (see Patent Document 1). However, since the fibrous activated carbon is cottony, the packing density cannot be increased, so there are problems that the adsorption performance per unit volume is not high, the manufacturing process is complicated, the manufacturing cost is extremely high, and it is not economical. .

The present inventors further perform an activation treatment by carbonizing plant biomass at 300 to 900 ° C. under reduced pressure, or after carbonizing at 200 to 900 ° C. under reduced pressure and / or in an inert atmosphere. The carbonized or activated product having a specific surface area of 200 m ² / g or more and an average pore width of 2.0 nm or more obtained by the above can be suitably used for removing trace components in hydrocarbon oil, particularly It has been found that the activated carbon obtained as described above using rice husk as a raw material is excellent in the adsorption ability of dibenzothiophenes, which are hardly desulfurized compounds in fuel oil (see Patent Document 2). In addition, a binder made of other carbon sources, especially sugars, is added to plant biomass or a pre-carbonized product of plant biomass, particularly carbide of rice husk, and after kneading and molding, the resulting molded product is carbonized. By a manufacturing method including a molding carbonization process for obtaining a molded carbonized product, and an activation process step for impregnating the obtained molded carbonized product with a binder and then activating this to obtain a molded activated product, It has been found that activated carbon having a high surface area, hard and high bulk density can be obtained (see Patent Document 3).

  However, rice husk contains a large amount of ash, especially silica, so the carbon content per unit mass is small, and if the activation treatment time is increased in order to increase the specific surface area, the carbon content decreases and the proportion of ash As a result, the improvement of the specific surface area per unit mass was limited.

International Publication No. 2003/097771 JP 2007-284337 A JP 2009-072712 A

  Therefore, the present invention is an activated carbon having a high specific surface area and a high bulk density, while retaining mesopores suitable for removing trace components in a liquid, and the trace components in a liquid such as hydrocarbon oil. It is an object to provide activated carbon that can be efficiently adsorbed and removed. The present invention also provides a method for producing the activated carbon, a method for purifying a liquid using the activated carbon, for example, a purification method for removing trace components in hydrocarbon oil using the activated carbon, and a fuel cell using the purification method. The problem is to provide a system.

  In order to achieve the above object, the present inventors have prepared a pretreatment method such as rice husk as a raw material of activated carbon which is a main material of an adsorbent for adsorbing and removing a trace component in a liquid, a carbon source added to rice husk and the like and an appropriate As a result of intensive investigations on the production conditions such as the selection of an appropriate binder and its addition amount, carbonization / activation treatment temperature, etc., as a result of plant biomass, preferably rice husk carbide obtained from rice or carbon sources further added to the rice husk carbide, particularly By maintaining a mesopore that is suitable for removing trace components in a liquid, the carbide obtained by adding carbon is treated with an alkali, especially an aqueous sodium hydroxide solution, to remove a part of the ash. However, the inventors have found that activated carbon having a high specific surface area and a high bulk density can be obtained, and the present invention has been completed.

That is, the present invention includes the following inventions.
(1) The specific surface area Sa is 800 to 4,000 m ² / g, the total pore volume Va is 0.5 to 1.2 cm ³ / g, and the ash content is 3 to 10% by mass. Activated carbon characterized by being.
(2) The activated carbon as described in (1) above, wherein the average pore width d determined by the following formula (I) is 1.0 to 2.0 nm.
d = 2000 × Va / Sa (I)
(3) The activated carbon as described in (2) above, wherein the mesopore volume Vm having a pore width of 2.0 nm or more and less than 50 nm is 0.1 to 0.5 cm ³ / g.
(4) The activated carbon as described in (3) above, wherein the ratio Vm / Va of the mesopore volume Vm to the total pore volume Va is 0.2 to 0.5.
(5) The ratio Vu / Vs of the ultra micro pore volume Vu having a pore width of less than 0.7 nm to the super micro pore volume Vs having a pore width of 0.7 nm or more and less than 2.0 nm is 1.0 to 2.5. The activated carbon as described in (1) above, wherein
(6) A method for producing activated carbon comprising a step of carbonizing and activating a raw material containing rice husks of 40% by mass or more, further comprising a step of removing ash from the activated carbon by alkali treatment. (1) The manufacturing method of activated carbon in any one of (5).
(7) Carbonizing a raw material containing 40% by mass or more of rice husks to obtain a carbonized product, removing the ash by alkali treatment of the carbonized product, and then activating the carbonized product. The method for producing activated carbon according to (6) above.
(8) The method for producing activated carbon as described in (7) above, wherein the carbonized product is molded after the alkali treatment.
(9) By adsorbing and removing the adsorbent comprising the activated carbon according to any one of (1) to (5) above or the adsorbent containing the activated carbon and the liquid, the liquid is adsorbed and removed. A method for purifying a liquid characterized by the above.
(10) The method for purifying a liquid as described in (9) above, wherein the liquid is kerosene or light oil.
(11) The method for purifying a liquid as described in (9) or (10) above, wherein the trace component is an aromatic compound.
(12) The method for purifying a liquid according to (11), wherein the aromatic compound is at least one sulfur compound selected from the group consisting of benzothiophenes and dibenzothiophenes.
(13) The method for purifying a liquid according to (12), wherein the sulfur compound is adsorbed and removed using a solid acid adsorbent as a post-treatment in the step of bringing the adsorbent into contact with the liquid.
(14) The method for purifying a liquid according to any one of the above (9) to (13), wherein the adsorbent and the liquid are contacted at a temperature of 0 to 80 ° C.
(15) A fuel cell system using the method for purifying a liquid according to any one of (9) to (14).

  According to the activated carbon of the present invention, since the adsorption performance per unit weight (mass) is higher than the original, the adsorption performance per unit volume (volume) is high. Adsorption and removal can be performed efficiently. Further, it is possible to provide a liquid purification method using such activated carbon as an adsorbent, and a fuel cell system using the purification method.

The manufacturing flowchart of activated carbon [N5AC EX 1 + 2h] (Comparative Example 1) is shown. The adsorption isotherm of each sulfur compound in the immersion type desulfurization test-1 using model oil is shown. The adsorption isotherm of the sulfur compound in the immersion-type desulfurization test-2 using model oil is shown. The manufacturing flowchart of activated carbon [N5AC60 Na1N EX 0.5h] (Comparative Example 6) and activated carbon [N5AC60 Na1N EX 0.25 + 0.5h] (Comparative Example 7) is shown. The manufacturing flowchart of activated carbon [N5AC85 Na1N EX 0.5h] (Example 3) and activated carbon [N5AC85 Na1N EX 0.25 + 0.5h] (Comparative Example 8) is shown. The manufacturing flowchart of activated carbon [N5AC Na1N EX 0.5h] (Example 4) and activated carbon [N5AC Na1N EX 0.25 + 0.5h] (Example 5) is shown. The adsorption isotherm of each sulfur compound in immersion type desulfurization test -3 using model oil is shown. The adsorption isotherm of each sulfur compound in immersion type desulfurization test -4 using model oil is shown. The adsorption isotherm of each sulfur compound in immersion type desulfurization test -5 using model oil is shown. The adsorption isotherm of dibenzothiophenes in the immersion desulfurization test using commercial kerosene is shown.

[Plant biomass]
The activated carbon production method of the present invention uses plant biomass as the main raw material. Here, plant-type biomass turns into a shaping | molding activation process thing through processes, such as a carbonization process process and an activation process process. Examples of plant biomass include wood, coconut husk, rice straw, rice husk, and pulp waste liquor. Rice husk is preferred, and rice husk obtained from rice is particularly preferred. A molded activated product obtained from plant biomass such as rice husk is a kind of so-called activated carbon, and the adsorbent comprising this is a trace component contained in a liquid, particularly a sulfur compound contained in a hydrocarbon oil and / or Or, it exhibits excellent performance in adsorption removal of polycyclic aromatic compounds.

  In the case of plant biomass, particularly rice husk, it is presumed that ash (inorganic components) such as silica contained develops mesopores and macropores. In particular, the mesopores need to have an appropriate capacity as a route for the diffusion of the trace components that are adsorbates. The amount of ash contained in plant biomass is about 20% by mass for rice husks and about 1% by mass for cedars.

  Furthermore, rice husks have the advantage that they are produced in a stable amount each year and can be supplied stably, and most of them are incinerated, which contributes to the effective use of resources. In addition, the raw material used for the manufacturing method of the activated carbon of this invention is not specifically limited as long as it contains 40 mass% or more of rice husk, You may use rice husk in combination with plant-type biomass other than this rice husk.

[Additional carbon source]
In the method for producing activated carbon of the present invention, it is preferable to use an additional carbon source in addition to the raw material made of plant biomass such as rice husk. If the plant biomass is activated carbon as it is, the carbon content is reduced in the carbonization step and the activation treatment step, and even the carbon content that forms micropores necessary for a high specific surface area may be reduced. It may not be possible to improve. By adding a carbon source to the skeleton obtained from the plant-based biomass, more micropores can be formed. In addition, the amount of additional carbon source used (the total amount used in the case where it is added divided into a plurality of times) is based on the remaining amount excluding moisture as a standard (dry standard) with respect to 100 parts by mass of the plant biomass. The range of 1 to 200 parts by mass, preferably 10 to 180 parts by mass, and more preferably 30 to 160 parts by mass is preferable.

  As the additional carbon source, saccharides are preferable from the viewpoint of carbon content and viscosity. Sugars include sugar beet juice, sugar cane juice, sugar beet sugar, sugar cane sugar, molasses, molasses, molasses, molasses sugar, brown sugar, sugar, sucrose, starch, oligosaccharide, etc. It is done. These are mainly composed of carbohydrate-based components such as cellulose, saccharides and starch, and are familiar (affinity, structural similarity) because the main component is the same carbohydrate as the plant-based biomass that is the raw material of activated carbon. The mixing property between the two is good, the strength of the obtained activated carbon is increased, and the specific surface area is also improved. Among these, sugar beet juice, sugar beet juice, beet sugar, sugar cane sugar, brown sugar and starch, which are relatively easily available, are preferred, and beet juice juice and sugar beet sugar are particularly preferred.

  Since the above saccharides are not sticky in the dry state, they can be used as they are when they are in liquid form, such as juice, for use as a binder. Are preferably used. In addition, the saccharide is often handled in a solid or powder form with a reduced water content. When the saccharide is in such a solid state or dry state, it may be used after being dissolved in water, or may be boiled and concentrated as necessary, like juice.

  The binder is mixed with plant-based biomass or carbonized material that is difficult to mold, and is hardened by using the adhesive strength of the binder to obtain a molded carbonized material, and the carbonized material or carbonized carbonized material. In order to improve the specific surface area and strength of the treated product, there is an impregnation binder used by impregnating plant biomass or a carbonized product before carbonization treatment or before activation treatment.

  The molding binder can be obtained, for example, by adding approximately the same mass of water to powdered or solid saccharides and stirring to prepare a uniform saccharide aqueous solution. At this time, when heated, the solubility increases and the saccharide can be dissolved quickly. In addition, when the mixture is boiled, a strong stirring effect is added, and a uniform aqueous sugar solution can be obtained efficiently. When the water is evaporated by continuing gentle boiling, a viscous syrupy liquid (aqueous sugar solution) that can be suitably used as a binder for molding can be obtained. The molding binder is used to strongly bond components such as a carbon material in a shape suitable for use as an adsorbent and to facilitate the molding process. If the water content is too high, it becomes impossible to mold and the processing efficiency is impaired. If the amount of water is too small, it can be adjusted by adding water during mixing or kneading. Therefore, it is preferable to use a syrup-like sugar aqueous solution having a moderate viscosity, for example, a viscosity of about loose honey. The viscosity can be adjusted by the amount of moisture. To increase the viscosity, add a large amount of water once to prepare a sugar solution with a sufficiently uniform composition, and then evaporate the water by heating to prepare a syrup-like sugar solution with the desired viscosity. Is preferred.

  The amount of the binder used for molding is not particularly limited as long as the amount that the plant-based biomass or carbonized product can be molded into a desired shape is not particularly limited, but the dried plant-based biomass or carbonized product to be molded is processed. It is preferable to use about 1 to 200 parts by weight, preferably about 5 to 100 parts by weight, and more preferably about 10 to 50 parts by weight with respect to 100 parts by weight. In addition, the usage-amount of said binder is based on the residual amount except a water | moisture content (dry standard).

As the impregnation binder, an aqueous sugar solution having a viscosity much lower than that of the molding binder in which powdered saccharides are uniformly dissolved in water having a mass of 1 to 20 times at about 60 ° C. can be used.
In addition, these binders may be used for carbonized products, activated products, dried plant biomass, pre-carbonized products, etc., where carbonized products or activated products or dried plants Although the usage-amount of the binder with respect to a system biomass or a preliminary carbonization processed material is not specifically limited, About 1-200 mass parts (dry basis) with respect to 100 mass parts of said processed materials, Preferably it is 5-160 mass. Parts, more preferably 20 to 140 parts by weight (dry basis). When the usage-amount of a binder is less than 5 mass parts, the intensity | strength of the activated carbon obtained will become low. On the other hand, when the amount is more than 200 parts by mass, the pore structure which is a feature of activated carbon such as rice husk cannot be obtained sufficiently.

[Pre-carbonization process (process to obtain pre-carbonized product)]
In the method for producing activated carbon of the present invention, it is preferable to first pre-carbonize plant biomass by heating in an inert atmosphere to obtain a pre-carbonized product. Here, the carbonization temperature is preferably a relatively low temperature of 200 to 600 ° C. In the present invention, preliminary carbonization means carbonization performed at a relatively low temperature. By performing this preliminary carbonization treatment, moisture and volatile components that volatilize at the above-mentioned temperature are removed. In the subsequent carbonization treatment process and activation treatment process, problems such as cracks in the processed products due to these volatile components, and the carbonization furnace In addition, unnecessary fouling of the activation furnace can be prevented, and the handleability is remarkably improved, so that the following processes, storage and transportation are facilitated.

Examples of the inert atmosphere include an inert gas atmosphere such as nitrogen and argon, and a vacuum atmosphere. From the viewpoint of economy and the like, it is preferable to perform a preliminary carbonization treatment in a nitrogen atmosphere. In addition, it is preferable to perform the carbonization time of the preliminary carbonization treatment for about 0.01 to 2 hours. Moreover, it is preferable to arrange the plant biomass in a size that is easy to handle when performing the preliminary carbonization treatment. For example, rice husks may be left as they are, but wood, coconut husks, rice straw etc. are preferably arranged in the shape of a so-called wood chip or toothpick of about 5 cm.
The preliminary carbonization treatment is not particularly limited as long as the carbonization treatment can be performed in an inert atmosphere. For example, the preliminary carbonization treatment can be performed using a furnace such as an atmospheric furnace or a rotary kiln.

[Carbonization process (process to obtain carbonized product)]
Next, the method for producing activated carbon of the present invention includes a step of carbonizing a plant biomass or a pre-carbonized product to obtain a carbonized product. Moreover, it is preferable that this carbonization process process is performed with respect to the molded material after shape | molding plant-type biomass or a preliminary | backup carbonized material.

  Here, when using plant-type biomass as it is for a carbonization process, it is preferable to dry and use beforehand. For example, it is dried at a temperature of 50 to 150 ° C., preferably 80 to 130 ° C. for about 1 to 24 hours.

  The dried plant biomass (hereinafter also referred to as dried plant biomass) or pre-carbonized product is pulverized to about 1 to 500 μm, preferably 2 to 100 μm, more preferably 5 to 50 μm, and if necessary, The molding binder, preferably a molding binder made of sugar, is added and mixed thoroughly. The blending amount of the molding binder is not particularly limited, but the molding binder is 1 to 200 parts by mass (dry basis), preferably 5 to 100 parts by mass of the dried plant biomass or the pre-carbonized product. It is preferable to uniformly mix 100 parts by weight (dry basis), more preferably 10 to 50 parts by weight (dry basis). The molding binder can be sufficiently uniformly mixed using a pulverized product of dried plant biomass or a pre-carbonized product and various commercially available mixing machines such as a stirrer, a mixer, a kneader, and a kneader. The resulting mixture is molded into a molded product using an appropriate molding machine, for example. When the state of the mixture is crumbly or a loose paste, it may not be pressure molded. In the case of papasa, a mixture can be prepared by adding water without changing the mixing ratio between the dried plant biomass or the pre-carbonized product and the saccharide in the molding binder. In the case of a loose paste, when the content of the dried plant biomass or the pre-carbonized product in the mixture is increased, the mixing ratio is changed. Therefore, it is preferable to prepare a syrup-like sugar aqueous solution having a high saccharide content to such an extent that the molding binder does not cause this.

  The shape of the molded product is not particularly limited, and examples thereof include a spherical shape, a granular shape, a columnar shape (the cross section has a deformed shape such as a circle, a corner, or a four-leaf shape), a cylindrical shape, a pellet shape, and a honeycomb shape. When the activated carbon finally obtained is used as an adsorbent, in order to increase the concentration gradient of the adsorbate (trace component), in the case of flow-through type, the shape is small as long as the differential pressure before and after the container filled with adsorbent does not increase In particular, a spherical shape is preferable. In the case of a spherical shape, the diameter is preferably 0.5 to 5 mm, particularly preferably 1 to 3 mm. In the case of a cylindrical shape, the diameter is preferably 0.1 to 4 mm, particularly preferably 0.2 to 2 mm, and the length is preferably 0.5 to 5 times the diameter, particularly preferably 1 to 4 times. The molding method of the molded product having such a shape is not particularly limited, and can be performed using various commercially available extrusion molding machines, press molding machines, tableting machines, tablet machines, and the like. Further, a pellet or columnar molded product can be obtained by combining a kneader and an extruder.

  Prior to carbonization, the molded product made of a mixture of the dried plant biomass or the pre-carbonized product and the molding binder thus obtained is, for example, 100 to 150 ° C, preferably 105 to 130 ° C. You may dry about 1-2 hours.

  Next, the dried plant biomass, pulverized product or molded product of the pre-carbonized product is carbonized in an inert atmosphere, preferably at 200 to 900 ° C. for 0.01 to 2 hours, and (molded) carbonized treatment. Get things. As in the case of the preliminary carbonization treatment, the inert atmosphere includes an inert gas atmosphere such as nitrogen and argon, a vacuum atmosphere, etc. From the viewpoint of economy and the like, the carbonization treatment can be performed under a nitrogen stream. preferable. By flowing an appropriate amount of nitrogen gas, moisture and volatile components generated from a molded product and the like can be removed, and the atmosphere in the carbonization furnace can be made uniform. The carbonization temperature is more preferably 400 to 900 ° C, further preferably 500 to 900 ° C, and particularly preferably 700 to 900 ° C. It is preferable to carry out at a temperature equal to or higher than the temperature of carbonization treatment (impregnation carbonization treatment) after impregnation described below, and it is particularly preferable to carry out at the same temperature as the temperature of activation treatment described later. The carbonization time is more preferably 0.03 to 1 hour, and further preferably 0.05 to 0.2 hour. In addition, when the pulverized product of the dried plant biomass or the pre-carbonized product is carbonized, the obtained carbonized product may be molded. Here, the molding method and the shape of the molded product are as described above.

  In addition, before performing the carbonization treatment, it is possible to impregnate a dry plant biomass or a pre-carbonized product with a binder for impregnation made of saccharides to perform carbonization treatment (impregnation carbonization treatment). This is preferable because it can reduce unevenness and increase the specific surface area. The molding carbonization treatment at this time is carried out by impregnating a dry plant biomass or a pre-carbonized product with a binder for impregnation as a raw material, and carbonizing (impregnating carbonization). Except for using the obtained impregnated carbonized product, the same method as in the case of using the dried plant biomass or the pre-carbonized product can be used.

  As the impregnation method, a known method such as a spray method, a dipping method, or an evaporation to dryness method can be used. From the viewpoint of ease of operation, the spray method and the dipping method are preferable. For example, in the case of the spray method, the impregnation binder is uniformly sprayed on the dried plant biomass or the pre-carbonized product so as to be impregnated as uniformly as possible. The impregnation amount of the binder is preferably about 5 to 200 parts by mass (dry basis) with respect to 100 parts by mass of the dried plant biomass or the pre-carbonized product. If the desired amount cannot be impregnated by a single spray, the desired amount of binder can be impregnated by drying once and then spraying the impregnating binder again, and repeating this operation as necessary. In the case of dipping and impregnation, a desired amount can be impregnated by repeating the dipping and drying operations. The amount of binder impregnation does not change even when dried, for example, the saccharide's dry basis mass does not change, so the amount of each impregnation obtained each time impregnation is determined from the mass after impregnation and the saccharide concentration of the binder. Can do.

  After impregnation with the binder, drying is performed at 100 to 150 ° C., preferably 105 to 130 ° C. for about 1 to 2 hours, and carbonization treatment (impregnation carbonization treatment) is performed in an inert atmosphere to obtain an impregnated carbonized product. The impregnation into the dried plant biomass or the pre-carbonized product and the carbonization treatment after the drying (impregnation carbonization treatment) are preferably performed at 200 to 900 ° C. for 0.01 to 2 hours. The carbonization temperature is more preferably 400 to 900 ° C, still more preferably 500 to 900 ° C, and particularly preferably 700 to 900 ° C. The carbonization time is more preferably 0.03 to 1 hour, and further preferably 0.05 to 0.2 hour.

[Alkali treatment process]
The method for producing activated carbon of the present invention further includes a step of removing the ash content of the activated carbon by alkali treatment. Specifically, ash content (inorganic component) such as silica content by further treating the pre-carbonized product, carbonized product, or carbonized product such as intermediate product in the middle of the carbonization process with an alkali. Can be removed. In addition, if the carbonized product is molded before the alkali treatment, it can be carried out by a flow method or the like, so that the alkali treatment step is simplified. On the other hand, when the molding is performed after the alkali treatment, the bulk density can be further increased, and the performance of the adsorbent becomes higher. The molding method and the shape of the molded product are as described above. In addition, an alkali treatment may be applied to the molded activation treatment product after the activation treatment, and ash such as silica can be removed by the alkali treatment after the activation treatment, and micropores are also formed.

  Examples of the alkali include an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, an aqueous calcium hydroxide solution, an aqueous sodium carbonate solution, an aqueous sodium hydrogen carbonate solution, an aqueous potassium carbonate solution, an aqueous potassium hydrogen carbonate solution, and an aqueous ammonia solution. For example, 1 part by mass of a preliminary carbonized product, a molded carbonized product, or an intermediate product in the middle of the molded carbonization process is brought into contact with 10 to 500 parts by mass, preferably 50 to 200 parts by mass of an aqueous alkaline solution. . In the case of an aqueous sodium hydroxide solution, the concentration is 0.1 to 3 mol / L, preferably 0.5 to 1 mol / L. The alkali treatment temperature is preferably 10 to 90 ° C, more preferably 30 to 80 ° C. The alkali treatment time, for example, the immersion time is preferably 10 to 500 hours, more preferably 50 to 200 hours. For example, after extracting the ash, the carbonized product subjected to alkali treatment is washed with distilled water and dried. The ash extracted in the alkaline aqueous solution contains a large amount of silica, so it can be recovered and used as a fertilizer or a raw material for solar cells.

[Activation treatment step (step of obtaining an activation treatment product)]
Next, the manufacturing method of the activated carbon of this invention includes the process of obtaining the activation treatment product as activated carbon which can be used for an adsorbent by activating the carbonization treatment product obtained as mentioned above. Here, it is preferable that the carbonized material is impregnated with an impregnation binder (preferably, a binder made of saccharides), dried, and then subjected to an activation treatment.

  As the impregnation method, a known method such as a spray method, a dipping method, an evaporation to dryness method or the like can be used which is impregnated with the above-mentioned dried plant biomass or pre-carbonized product. Among these, the spray method and the dipping method are preferable from the viewpoint of ease of operation. When a desired amount of the binder for impregnation cannot be impregnated by one impregnation operation, the impregnation operation can be performed again after drying once to increase the impregnation amount of the binder. By repeating this, a desired amount of the molding binder can be impregnated.

The carbonized product impregnated with the binder is dried at 100 to 150 ° C., preferably 105 to 130 ° C. for about 1 to 2 hours, and subjected to activation treatment. Examples of the activation treatment include gas activation, water vapor activation, and drug activation. In the case of drug activation, after the activation process, a post-treatment that removes the drug (KOH, NaOH, ZnCl ₂ , H ₂ SO _4, etc.) used in the activation process from the activation process is required, which is troublesome and takes time. On the other hand, gas activation or water vapor activation may be performed by heat treatment in a gas atmosphere or a water vapor atmosphere, and does not require an extra complicated operation for removing the drug. Therefore, steam activation or gas activation is preferred.

  Examples of the gas used for steam activation and gas activation include water vapor, carbon dioxide gas, air, combustion gas, etc., but gas activation using carbon dioxide makes it easy to control the activation treatment conditions and handle the gas. In addition, it is preferable because post-treatment after the activation treatment is easy. Specifically, the carbonized product impregnated with the binder and dried is subjected to an activation treatment temperature of preferably 800 to 900 ° C. for 0.1 to 4 hours, more preferably 0.5 to 3 in a carbon dioxide atmosphere. The heat treatment is performed for a time, more preferably 0.7 to 2.3 hours. The carbon dioxide atmosphere means that the activation gas in the furnace containing the carbonized material is carbon dioxide, and 100% carbon dioxide may be used, but inert gas such as nitrogen gas or argon gas. Alternatively, it is preferable to use a gas in which carbon dioxide is mixed with combustion gas, water vapor or the like.

  After impregnating the binder for impregnation as described above, the activation treatment product obtained by the activation treatment can be impregnated again with the binder for impregnation to carry out the activation treatment (two-stage activation treatment). According to the two-stage activation treatment, the obtained two-stage activation treatment product is preferable because a product having a relatively large specific surface area and total pore volume and a relatively large bulk density can be obtained. The impregnation, drying, and heat treatment in the two-stage activation treatment can be performed under exactly the same conditions as in the activation treatment.

[Physical properties of activated carbon]
The activated carbon of the present invention is an activation treatment product and / or a two-stage activation treatment product obtained by the above-described production method, and the specific surface area, average pore width, fineness of the activation treatment product and / or the two-stage activation treatment product. Pore characteristics such as pore volume greatly affect adsorption performance such as desulfurization. A large specific surface area is preferable because it means that there are many adsorption sites for adsorbates (trace components), but if the average pore width is narrow, no matter how large the specific surface area is, adsorbates with a large molecular weight are adsorption sites. The performance does not increase in actual use. The average pore width is proportional to the pore volume and inversely proportional to the specific surface area. If the average pore width is too large, the pore volume is too large to obtain a sufficient density, and the adsorption capacity per unit volume becomes low. On the other hand, if the average pore width is too large, the specific surface area is too small to obtain sufficient adsorption sites, and the adsorption capacity is also lowered. Therefore, these balances are important.

The specific surface area Sa of the activated carbon of the present invention is required to have a 800~4,000m ² / g, it is preferably ^{900~2,000m 2 / g, 1,000~1,500m 2 /} g is Particularly preferred. Pore volume (total pore volume) Va is required to be a 0.5~1.2cm ³ / g, it is preferably 0.6~1.0cm ³ / g.

In activated carbon made from rice husks, inorganic components such as silica serve as a mesopore skeleton, and the mesopore volume is large, but the specific surface area is not so large because the micropore volume is generally small. By supplying an additional carbon source such as sugar beet, the specific surface area gradually increases, but in order to realize such pore characteristics, it is necessary to repeat the carbon source addition and carbonization steps many times. It was not right.
The inventor found that mesopores were formed at the stage where the rice husks were pre-carbonized, and the role of most of the silica was completed, but if included in the activated carbon as it is, the formation of micropores was inhibited. As a result, the present invention has been achieved. That is, when mesopores are formed, inorganic components such as silica are removed, and the activation process is performed after increasing the proportion of carbon contained in the activated carbon, so that mesopores suitable for removing trace components in the liquid are obtained. It has been found that activated carbon having a high specific surface area and high bulk density can be produced while maintaining the above, and that the activated carbon can efficiently adsorb and remove trace components in a liquid such as hydrocarbon oil.

  As a method for removing inorganic components such as silica, a method of dissolving with an alkali or an acid can be considered. A treatment with an alkali is preferable because it has little influence on the carbon content.

  Moreover, mesopores cannot be maintained if inorganic components such as silica are completely removed. As a result, a high mesopore volume ratio with respect to the micropore volume suitable for removing trace components in the liquid cannot be realized. Therefore, the content of ash (inorganic component) in the activated carbon is required to be 3 to 10% by mass, preferably 4 to 9% by mass, and particularly preferably 4 to 7% by mass.

In the activated carbon of the present invention, the average pore width d [nm] obtained by the following formula (I) is preferably such that the adsorbate is easily diffused, that is, 1.0 to 2.0 nm, more preferably 1.2 to 1. .8 nm, particularly 1.3 to 1.7 nm is preferable.
d = 2000 × Va / Sa (I)
In the above formula (I), Va [cm ³ / g] is the total pore volume, and Sa [m ² / g] is the specific surface area.

Mesopores having a pore width of 2.0 nm or more and less than 50 nm are important as an adsorbate diffusion route, but if they are more than necessary, the micropore volume that is an adsorption site is insufficient. Therefore, the activated carbon of the present invention preferably has a mesopore volume Vm having a pore width of 2.0 nm or more and less than 50 nm of 0.1 to 0.5 cm ³ / g, preferably 0.1 to 0.3 cm ³ / g. More preferably. From the same viewpoint, the ratio Vm / Va of the mesopore volume Vm to the total pore volume Va is preferably 0.2 to 0.5, and more preferably 0.3 to 0.4.

  Micropores can be classified into supermicropores with a pore width of 0.7 nm or more and less than 2.0 nm, and ultramicropores with a pore width of less than 0.7 nm. It is a micropore, and the supermicropore mainly contributes to the diffusion of the adsorbate. Therefore, although the adsorption performance is higher when the ultra-micro pore volume is larger, super-micro pores that can diffuse the adsorbate to the ultra-micro pores are also required. Therefore, the activated carbon of the present invention has a ratio Vu / Vs of the ultra micro pore volume Vu having a pore width of less than 0.7 nm to the super micro pore volume Vs having a pore width of 0.7 nm or more and less than 2.0 nm of 1.0 μm. Is preferably -2.5, more preferably 1.1-2.3, and particularly preferably 1.2-1.9.

Pore characteristics can be analyzed using a gas adsorption analyzer (eg, Autosorb-3B, Cantachrome, Florida, USA). For example, first, at −196 ° C., an adsorption amount of nitrogen gas (referred to as a nitrogen adsorption isotherm) as a function of the relative pressure of nitrogen gas is obtained. From this nitrogen adsorption isotherm, the total pore volume, BET specific surface area, and average pore width are calculated. The total pore volume can be determined by the nitrogen adsorption volume at a relative pressure of 0.995. The BET specific surface area is determined by the nitrogen adsorption volume at a relative pressure of 0.05-0.10. The average pore width [nm] can be determined as 2000 × total pore volume [cm ³ / g] / BET specific surface area [m ² / g] assuming that the pores are slit-like. The adsorption capacity of the porous body cannot be explained entirely by the specific surface area and pore volume, but generally a high specific surface area or a large total pore volume is desirable. The pores are classified into micropores having a width of less than 2.0 nm, mesopores of 2.0 or more and less than 50 nm, and macropores of 50 nm or more. It is classified as a super micropore of 7 nm or more and less than 2.0 nm.

  The pore distribution of the pore volume as a function of the pore width can be analyzed using the Density Functional Theory (DFT) method. The DFT method is a method of obtaining a pore distribution through numerical analysis from the obtained nitrogen adsorption isotherm, and can be analyzed using, for example, DFT software (Cantachrome, Version 1.62). A large ultra-micro pore volume is preferable because the specific surface area is large and the number of adsorption sites is large. Further, when the mesopore volume is large, the pore width is increased, and the sulfur compound is easily moved to the adsorption site. Therefore, activated carbon having a large ultramicro pore volume and mesopore volume is preferred. Since rice husk activated carbon contains silica, the mesopore volume is inherently large. Therefore, a production method for increasing the ultramicropore volume without reducing the mesopore volume is effective. According to the above-mentioned method for producing activated carbon, the effect of suppressing the decrease in the mesopore volume to the minimum and increasing the ultramicropore volume is remarkable.

[Liquid purification method]
The liquid purification method of the present invention is characterized by adsorbing and removing trace components contained in the liquid by bringing the liquid into contact with an adsorbent comprising the activated carbon or an adsorbent containing the activated carbon. As a post-treatment in the step of bringing the adsorbent into contact with the liquid, it is preferable to adsorb and remove the sulfur compound using a solid acid adsorbent described later.

[Adsorbent]
The adsorbent used in the liquid purification method of the present invention consists of the above-mentioned activated carbon alone or contains the activated carbon. For this reason, the activated carbon may be used as the adsorbent as it is, or activated carbon as described later. Can be used after being kneaded and molded with zeolite or the like, or can be used by improving the performance by supporting active metal on activated carbon. In addition, activated carbon may be used as it is as the adsorbent used in the liquid purification method of the present invention. Therefore, the pore characteristics such as the specific surface area, average pore width and pore volume of the activated carbon are as described above for the activated carbon. The same pore characteristics as the range can be applied.

  When adsorbing and removing sulfur compounds and / or polycyclic aromatic compounds contained in hydrocarbon oils such as kerosene and light oil, the above-mentioned moldings such as powdered, particulate, or spherical, disc-shaped, cylindrical molded products, etc. It can be used in any form similar to the shape of the molded product in the carbonization process. An adsorbent having a suitable shape may be selected and used in accordance with the processing amount of hydrocarbon oil and the situation of equipment.

  When used in powder or particulate form, the activated carbon is pulverized with a known appropriate pulverizer and then classified with a known appropriate classifier to obtain a powder or average particle having an average particle diameter of about 0.5 μm to 0.1 mm. The activated carbon can be appropriately used according to use conditions by sieving it into particulate activated carbon having a diameter of about 0.1 to 5 mm.

  When hydrocarbon oil is continuously supplied to and passed through the adsorbent and used, and when the deteriorated adsorbent is regenerated and used repeatedly, it is preferable to use activated carbon as a molded product. Since the activated carbon of the present invention activates the molded carbonized product, it can be suitably used as it is. Therefore, in the molding process of the molding carbonization process to obtain the molded carbonized product, it is pre-molded into a shape suitable for the application conditions such as the hydrocarbon oil to be processed and its processing conditions, and after activation treatment and after metal loading It is preferable to maintain the shape. After the activation treatment, the activated carbon may be pulverized and mixed with an inorganic substance such as zeolite or a supported metal, and then molded into an appropriate shape.

  As the shape of the molded product, in order to increase the concentration gradient of trace components to be removed, such as sulfur compounds, in the case of flow-through type, the shape is small, especially spherical, so long as the differential pressure before and after the container filled with the adsorbent does not increase Is preferred. In the case of a spherical shape, the size is preferably 0.1 to 5 mm, particularly 0.3 to 3 mm. In the case of a cylindrical shape, the diameter is preferably 0.1 to 4 mm, particularly preferably 0.12 to 2 mm, and the length is preferably 0.5 to 5 times, particularly 1 to 4 times the diameter. The molded article preferably has a breaking strength of 0.5 kg / pellet or more, particularly 1.0 kg / pellet or more so as not to crack during use as an adsorbent. The breaking strength is measured, for example, by a compressive strength measuring device such as a Kiya tablet breaking strength measuring device (manufactured by Toyama Sangyo Co., Ltd., TH-203MP).

  In the liquid purification method of the present invention, the activated carbon used for the adsorbent is a sulfur compound or the like in order to improve the adsorption performance of sulfur compounds and the like that are difficult for activated carbon to adsorb and / or increase the amount of mesopores and macropores. In order to improve the diffusion rate, inorganic substances such as silica, alumina, zeolite and the like may be mixed during or after carbonization, molding, and activation.

  In the liquid purification method of the present invention, the activated carbon used for the adsorbent is a metal such as silver, mercury, copper, cadmium, lead, molybdenum, zinc, cobalt, manganese, nickel, platinum, palladium, iron and / or the like. Adsorption performance can also be improved by compounding with these metal oxides, that is, by supporting these metals. From the viewpoint of safety and economy, the oxides of copper, silver, manganese, zinc, and nickel are preferable. Among these, copper is inexpensive and has excellent performance for adsorption of sulfur compounds in a wide temperature range from near room temperature to about 300 ° C., in the state of copper oxide without reduction treatment, and in the absence of hydrogen. This is particularly preferable.

  The preferred loading amount of the metal is not particularly limited and varies depending on the type of metal, but is 0.1 to 20% by mass, particularly 0.5 to 5% in the case of a noble metal on the basis of the metal with respect to the finished adsorbent. It is preferable that it is mass%. If the amount of metal supported is less than 0.1% by mass, the effect of supporting is small, and if it exceeds 20% by mass, it is not economical. In the case of copper and other metals, the metal is preferably supported in an amount of 0.1 to 60% by mass, particularly 3 to 20% by mass. If the supported amount of the metal is less than 0.1% by mass, the effect of supporting is small, and if it is more than 60% by mass, the amount of the metal that is weakly bonded to the activated carbon that is the carrier increases, so that the metal component may be detached. is there. When the amount of metal supported is large, the adsorption performance of sulfur compounds such as thiophenes and benzothiophenes that are difficult to adsorb activated carbon can be further improved.

  The method for supporting these metals is not particularly limited, and any method that supports a desired amount of metal and exhibits desired performance may be used. For example, a molded activated product (activated carbon) is impregnated with an aqueous solution of metal hydroxide or nitrate by spraying or dipping, or the activated carbon is pulverized and an aqueous solution of metal hydroxide or nitrate is kneaded. After molding and drying, the adsorbent can be obtained by further heating and removing moisture or nitric acid so as not to lose the carbon component.

〔liquid〕
Examples of the liquid to which the adsorbent used in the liquid purification method of the present invention is applicable include hydrocarbon oil and various wastewaters. In the adsorption in liquid (so-called liquid phase adsorption), the molecular weight of the adsorbate is generally large and the viscosity of the liquid is high. Therefore, the diffusion of the adsorbate is slow and it is easily affected by the pore wall. Since the adsorbent used in the liquid purification method of the present invention has pore characteristics suitable for liquid phase adsorption, an excellent effect can be obtained particularly in liquid phase adsorption.

  Examples of the hydrocarbon oil include hydrocarbon oils containing 5 to 20 carbon atoms containing dibenzothiophenes as sulfur compounds or containing polycyclic aromatic compounds. Specific examples include kerosene and light oil, and particularly kerosene for fuel cells that needs to be highly desulfurized (deep).

  These hydrocarbon oils may contain any kind of sulfur compounds such as thiophenes, mercaptans (thiols), sulfides, disulfides, carbon disulfide, etc. It exerts a remarkable effect on hydrocarbon oils containing sulfur compounds such as dibenzothiophenes that are extremely difficult to do. For example, the ratio of dibenzothiophenes to the total sulfur compounds is about 30% for kerosene and almost 100% for light oil, and hydrocarbon oils such as kerosene and light oil are preferred hydrocarbon oils for application of the adsorbent. Of course, the application target of the adsorbent used in the liquid purification method of the present invention is not limited to kerosene or light oil.

  For qualitative and quantitative analysis of these sulfur compounds, Gas Chromatograph (GC) -Flame Photometric Detector (FPD), GC-Atomic Emission Detector (AED), GC- Sulfur Chemiluminescence Detector (SCD), GC-Inductively Coupled Plasma Mass Spectrometer (ICP-MS), etc. can be used, but GC-ICP is used for mass ppb level analysis. -MS is most preferable (see JP 2006-145219 A).

[Minor components]
An aromatic compound can be mentioned as a trace component which the adsorption agent used for the purification method of the liquid of this invention makes adsorption object. Adsorption by the interaction of π electrons on the graphite surface partially present on the activated carbon and π electrons on the benzene ring of the aromatic compound (so-called π electron adsorption) makes the adsorbent superior in adsorbing aromatic compounds. Show the effect.

  Examples of aromatic compounds include sulfur compounds such as benzothiophenes and dibenzothiophenes, polycyclic aromatic compounds containing two or more benzene rings, and humins contained in wastewater.

  A polycyclic aromatic compound is a compound having two or more benzene rings and may contain heteroatoms other than carbon and hydrogen, but all the carbons forming the two benzene rings are in the same plane. The one located above has a stronger π-electron interaction with the adsorbent, and the effects of the present invention can be remarkably obtained.

  Humins are also called humic substances and include humic acid and the like. It is a final decomposition product obtained by decomposition of a plant or the like with a microorganism, and is a compound having an aromatic skeleton and a molecular weight of several thousand or more.

  When impurities such as sulfur and polycyclic aromatic compounds are removed from the hydrocarbon oil with the above adsorbent, if the content of these impurities is too large, a large amount of adsorbent is required, which is uneconomical. In such a case, since other purification methods such as hydrorefining methods are more efficient, the sulfur content in the hydrocarbon oil to be handled in the present invention is preferably 20 ppm by mass or less, and preferably 10 ppm by mass or less. Is more preferably 1 ppm by mass or less, and the content of the polycyclic aromatic compound is preferably 5% by mass or less, more preferably 2% by mass or less, and further preferably 0.5% by mass or less.

[Method for adsorption removal of trace components]
It is preferable to remove a small amount of moisture adsorbed on the adsorbent as a pretreatment before use. Moisture removal may be performed at about 100 to 200 ° C. in an oxidizing atmosphere such as air. However, when the temperature exceeds 200 ° C., oxygen in the air reacts with the carbon component of the adsorbent to reduce the mass of the adsorbent, which is not preferable. On the other hand, the adsorbent can be dried at about 100 to 800 ° C. in a non-oxidizing atmosphere such as nitrogen. In particular, it is more preferable to heat-treat the adsorbent at 400 to 800 ° C. in a non-oxidizing atmosphere because organic substances and oxygen-containing functional groups are removed and the adsorption performance is improved.

  In the liquid purification method of the present invention, the method of bringing the adsorbent into contact with the hydrocarbon oil may be batch type (batch type) or continuous type, but the hydrocarbon oil is circulated in the container filled with the adsorbent of the molded product. The continuous system is efficient and preferable.

In the case of the continuous type, the pressure is preferably from normal pressure to 1.0 MPaG, more preferably from normal pressure to 0.1 MPaG, and particularly preferably from 0.001 to 0.03 MPaG. Flow rate is preferably 0.001～100Hr ^-1 at a liquid hourly space velocity (LHSV), 0.01~10hr ^-1 are more preferred. The apparent linear velocity (the value obtained by dividing the liquid flow rate by the cross-sectional area of the adsorbent layer) is 0.001 to 100 cm / min, more preferably 0.005 to 10 cm / min, and particularly 0.01 to 1 cm / min. preferable. If the apparent linear velocity is high, the moving speed of the liquid phase itself passing through the packed bed of adsorbent is faster than the adsorption speed (moving speed from the liquid phase to the solid phase), and the liquid phase reaches the outlet of the adsorbing layer. The adsorbate cannot be completely removed by this time, and the liquid tends to flow out from the outlet while containing the adsorbate that is not removed. Conversely, if the apparent linear velocity is low, the cross-sectional area of the adsorbent layer becomes relatively large, so that the liquid dispersion state becomes poor, and the flow velocity of the liquid passing through the cross section perpendicular to the flow direction of the adsorbent layer ( The flow rate is uneven, and the adsorbate adsorbed in the cross section of the adsorbent layer is distributed (unevenness). Therefore, the load on the adsorbent becomes non-uniform and desulfurization cannot be performed sufficiently efficiently.

  The temperature at which the adsorption treatment is performed (that is, the temperature at which the adsorbent is brought into contact with the liquid) is preferably -30 to 100 ° C, and particularly preferably 0 to 80 ° C. At a temperature lower than −30 ° C., the diffusion rate of the adsorbed substance (adsorbate) in the liquid is remarkably small, and it takes a long time to be adsorbed. In addition, since the viscosity of the liquid is increased, in the case of a flow type packed in a column, the pressure loss in the column increases, and the column inlet pressure needs to be increased. In general, 0 ° C. or higher is particularly preferable. On the other hand, when the temperature is higher than 100 ° C., the adsorption amount at equilibrium is remarkably reduced due to physical adsorption. The higher the temperature, the higher the adsorption rate, but the lower the amount of physical adsorption at equilibrium, so 80 ° C. or less is particularly preferable.

[Fuel cell system]
Since the fuel cell system of the present invention is characterized by using the above-described liquid purification method, the fuel cell system includes an adsorption means for adsorbing and removing trace components from the liquid. As a trace component, a sulfur compound is mentioned, for example. Here, as the adsorbing means, the above-described adsorbent can be used alone, but may be used in combination with other adsorbents. In addition to the adsorbing means, the fuel cell system of the present invention usually includes a reforming means for reforming hydrocarbon oil from which trace components have been removed to generate a reformed gas containing hydrogen, a fuel cell, Is provided. Here, a known reforming catalyst is usually used as the reforming means. In the fuel cell system of the present invention, the adsorbent, the reforming catalyst and the hydrocarbon may be brought into contact with each other by a batch type (batch type) or a flow type. The flow type in which the hydrocarbon oil is circulated while being filled in is more preferable.

  In the fuel cell system of the present invention, the adsorbent used in the purification method (hereinafter also referred to as the adsorbent of the present invention) is particularly excellent in the removal performance of dibenzothiophenes, so that benzothiophenes, mercaptans, or sulfides For the removal of other adsorbents, such as benzothiophenes, such as benzothiophenes, the solid acid catalyst and / or transition metal oxide previously proposed by the present inventor is supported. Desulfurization agents such as activated carbon (see WO 2005-073348 pamphlet) and mercaptans for removal of copper oxide-supported alumina previously proposed by the present invention (see JP 2000-42407), removal of sulfides Is preferably a combination with zeolite or the like (see JP 2001-205004 A).

In particular, since kerosene mainly contains benzothiophenes and dibenzothiophenes, it is preferable to use a combination of the adsorbent of the present invention and a solid acid adsorbent for desulfurization of kerosene. As the solid acid adsorbent, an adsorbent containing a solid super strong acid is particularly preferable. The solid super strong acid means a solid acid having a higher acid strength than 100% sulfuric acid having a Hammett acidity function H ₀ of −11.93, such as silicon, aluminum, titanium, zirconium, tungsten, molybdenum, iron, and the like. Zirconium oxide (ZrO ₂₎ , or a carrier made of hydroxide, oxide, graphite, ion exchange resin, or the like, with a sulfate radical, antimony pentafluoride, tantalum pentafluoride, boron trifluoride or the like attached or supported thereon. ), Stannic oxide (SnO ₂ ), titania (TiO ₂ ), ferric oxide (Fe ₂ O ₃ ) or the like carrying tungsten oxide (WO ₃ ), and further fluorinated sulfonic acid resin, etc. (See International Publication No. WO2005-073348 Pamphlet). Among these, sulfate group alumina proposed by the present inventors is more preferable (see International Publication No. WO2009-031613 pamphlet). An adsorbent in which copper, silver, gallium or the like is supported on sulfate radical alumina is also preferably used.

  In the liquid purification method described above, as a post-treatment in the step of bringing the adsorbent into contact with the liquid, it is also preferable to adsorb and remove residual sulfur compounds using a solid acid adsorbent. The adsorbent of the present invention is an activated carbon-based adsorbent, and the adsorption isotherm of the sulfur compound in the activated carbon-based adsorbent is Freundlich type. Therefore, the higher the concentration of the sulfur compound, the higher the sulfur compound adsorption activity. It is effective to use at a high concentration stage. Therefore, first, it is preferable to adsorb and remove dibenzothiophenes with the adsorbent of the present invention and to adsorb and remove the remaining benzothiophenes with a solid acid adsorbent.

  Typically, hydrocarbon oils include kerosene and light oil. Kerosene with light hydrocarbon oil such as naphtha, and kerosene with heavy hydrocarbon oil such as light oil. In the form, those with a narrower boiling range than commercial kerosene, those obtained by removing certain components such as aromatics from commercial kerosene, light oil blended with light hydrocarbon oils such as kerosene, commercially available Those having a boiling point range narrower than that of the light oil, or those obtained by removing specific components such as aromatic components from commercially available light oil may be used.

  In addition, when hydrocarbon oil is used as a hydrogen source for a fuel cell or the like, sulfur contained in the hydrocarbon must be strictly removed because it is a catalyst poison of the reforming catalyst in the hydrogen production process. The fuel cell system of the present invention can reduce sulfur compounds to a very small concentration, and therefore can be particularly preferably used when kerosene or light oil is used as an onboard reformed fuel in a fuel cell vehicle. Therefore, the fuel cell system of the present invention can produce hydrogen and supply it to the fuel cell without poisoning the reforming catalyst for producing hydrogen. The fuel cell system of the present invention may be stationary or movable (for example, a fuel cell vehicle).

  The fuel cell system of the present invention has a significant effect on the removal of thiophenes, benzothiophenes and dibenzothiophenes, and is therefore suitable for hydrocarbon oils with a low content of other sulfur compounds, especially kerosene and light oil. More preferably it can be used.

Kerosene is an oil having mainly a hydrocarbon having about 12 to 16 carbon atoms, a density (15 ° C.) of 0.79 to 0.85 g / cm ³ , and a boiling point range of about 150 to 320 ° C. Although it contains a lot of paraffinic hydrocarbons, it contains about 0 to 30% by volume of aromatic hydrocarbons and about 0 to 5% by volume of polycyclic aromatics. In general, No. 1 kerosene defined in Japanese Industrial Standard JIS K2203 is used as a fuel for lighting, heating, and kitchen. Quality: flash point 40 ° C or higher, 95% distillation temperature 270 ° C or lower, sulfur content 0.008% by mass or lower, smoke point 23mm or higher (21mm or higher for cold weather), copper plate corrosion (50 ° C, 3 hours) ) There are provisions of 1 or less and color (Saebold) +25 or more. Usually, the sulfur content is from several ppm to 80 ppm by mass and the nitrogen content is from several ppm to 10 ppm by mass.

The light oil is an oil having mainly a hydrocarbon having about 16 to 20 carbon atoms, a density (15 ° C.) of 0.82 to 0.88 g / cm ³ , and a boiling point range of about 140 to 390 ° C. Although it contains a lot of paraffinic hydrocarbons, it also contains about 10-30% by volume of aromatic hydrocarbons and about 1-10% by volume of polycyclic aromatics. Sulfur is contained from several ppm to 100 ppm by mass, and nitrogen is contained from several ppm to several tens of ppm.

Benzothiophenes are heterocyclic compounds containing one or more sulfur atoms as heteroatoms, and the heterocycle is a penta- or hexa-atom ring and has aromaticity (two or more double bonds in the heterocycle). And a sulfur compound in which the heterocyclic ring is condensed with one benzene ring and derivatives thereof. Benzothiophene, also called thionaphthene or thiocoumarone, is a sulfur compound with a molecular weight of 134, which can be represented by the molecular formula C ₈ H ₆ S. Other representative benzothiophenes include methylbenzothiophene, dimethylbenzothiophene, trimethylbenzothiophene, tetramethylbenzothiophene, pentamethylbenzothiophene, hexamethylbenzothiophene, methylethylbenzothiophene, dimethylethylbenzothiophene, trimethylethyl Benzothiophene, tetramethylethylbenzothiophene, pentamethylethylbenzothiophene, methyldiethylbenzothiophene, dimethyldiethylbenzothiophene, trimethyldiethylbenzothiophene, tetramethyldiethylbenzothiophene, methylpropylbenzothiophene, dimethylpropylbenzothiophene, trimethylpropylbenzothiophene , Tetramethylpropylbenzothiophene, penta Chill propyl benzothiophene, methyl ethyl propyl benzothiophene, dimethyl ethyl propyl benzothiophene, trimethyl ethylpropyl benzothiophene, alkyl benzothiophenes such as tetramethyl-ethylpropyl benzothiophene, Chiakuromen (Benzochia -γ- pyran, molecular formula C _{9 H} 8 _S, Molecular weight 148), dithiaphthalene (molecular formula C ₈ H ₆ S ₂ , molecular weight 166) and derivatives thereof.

Dibenzothiophenes are heterocyclic compounds containing one or more sulfur atoms as heteroatoms, and the heterocycle is a penta- or hexa-atom ring and has aromaticity (two or more double bonds in the heterocycle). And a sulfur compound in which a heterocyclic ring is condensed with two benzene rings and derivatives thereof. Dibenzothiophene is also called diphenylene sulfide, biphenylene sulfide, or diphenylene sulfide, and is a sulfur compound having a molecular weight of 184 that can be represented by the molecular formula C ₁₂ H ₈ S. 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene are well known as difficult desulfurization compounds in hydrorefining. Other representative dibenzothiophenes include trimethyldibenzothiophene, tetramethyldibenzothiophene, pentamethyldibenzothiophene, hexamethyldibenzothiophene, heptamethyldibenzothiophene, octamethyldibenzothiophene, methylethyldibenzothiophene, dimethylethyldibenzothiophene, Trimethylethyldibenzothiophene, tetramethylethyldibenzothiophene, pentamethylethyldibenzothiophene, hexamethylethyldibenzothiophene, heptamethylethyldibenzothiophene, methyldiethyldibenzothiophene, dimethyldiethyldibenzothiophene, trimethyldiethyldibenzothiophene, tetramethyldiethyldibenzothiophene, Pentamethyldiethyldibenzo Offene, hexamethyldiethyldibenzothiophene, heptamethyldiethyldibenzothiophene, methylpropyldibenzothiophene, dimethylpropyldibenzothiophene, trimethylpropyldibenzothiophene, tetramethylpropyldibenzothiophene, pentamethylpropyldibenzothiophene, hexamethylpropyldibenzothiophene, heptamethylpropyl Alkyl dibenzothiophenes such as dibenzothiophene, methylethylpropyldibenzothiophene, dimethylethylpropyldibenzothiophene, trimethylethylpropyldibenzothiophene, tetramethylethylpropyldibenzothiophene, pentamethylethylpropyldibenzothiophene, hexamethylethylpropyldibenzothiophene, thianthre (Diphenylene disulfide, molecular formula _C 12 _H 8 _{S 2,} molecular weight 216), thioxanthene (dibenzo thiopyran, diphenylmethane sulfide, molecular formula _C 13 _{H 10} S, molecular weight 198) include and derivatives thereof.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

<< Model oil immersion type desulfurization test for activated carbon after activation treatment >>
[Preparation of activated carbon-1]
(Comparative Example 1)
The rice husk used was Akitakomachi rice husk from Nishiki Village, Akita Prefecture (currently Semboku City) in 2005.
Dry sugar beet sugar was added to distilled water, and it was kept until it thickened while stirring with a hot stirrer to obtain a sugar beet sugar syrup. This is defined as sugar syrup for penetration and soaking.

  The following carbonization treatment and activation treatment are performed by placing a rice husk sample in an alumina tube having an inner diameter of 100 mm and an outer diameter of 110 mm, flowing nitrogen or carbon dioxide gas as an atmospheric gas, and applying heat treatment to the rice husk sample using an electric furnace. It was conducted. When performing carbonization, the furnace temperature was raised to the target temperature and maintained at that temperature. Then, it naturally cooled and gradually lowered the temperature. The nitrogen gas flow rate was controlled at 1 L / min. When performing the activation process, carbon dioxide gas was used. It utilizes a reaction in which carbon reacts with carbon dioxide at 800 ° C. or higher and carbon is released as carbon monoxide. The activation treatment was performed in an electric furnace in the same manner as the carbonization treatment. The furnace temperature was raised to the target temperature in a nitrogen gas atmosphere. After reaching the target temperature, the nitrogen gas was switched to carbon dioxide gas. The flow rate of carbon dioxide gas was controlled to 1 L / min similarly to the flow rate of nitrogen gas. Thereafter, the furnace temperature was maintained, and the furnace temperature was gradually lowered by natural cooling.

  Pencil sugar syrup for infiltration and immersion was added to rice husk pre-carbonized at 250 ° C. And both were well coated and left overnight. What was left overnight was further carbonized at 600 ° C. for 1 hour in nitrogen.

  The carbonized product at 600 ° C. was pulverized to 5 to 50 μm. 100 parts by mass of the pulverized carbonized product and 40 parts by mass (dry basis) of high-concentration syrup (defined as sugarcane syrup for molding) mixed with sugar and water are thoroughly blended using a mortar and pestle. So mixed. The mixture was filled into a φ10 mm hole in which a small hole with a diameter of φ1.00 mm and a length of 10 mm was tapered at the bottom, and the mixture was passed through the small hole by pressurization. The pressure applied to the mixture existing in a small hole having a diameter of φ1.00 mm and a length of 10 mm was adjusted to about 19 GPa and extruded. The extruded molded product was cut into an appropriate length and dried at 105 ° C. for 1 hour.

  The dried extrudate was carbonized for 5 minutes at 850 ° C. in nitrogen. The carbonized product was immersed in a sugar syrup for penetration and soaking for 12 hours. Thereafter, the molded product was removed from the syrup and dried at 105 ° C. for 2 hours. The dried product was activated with carbon dioxide gas at 850 ° C. for 1 hour. It was further immersed in a sugar syrup for penetration and soaking for 12 hours. Thereafter, the molded product was removed from the syrup and dried at 105 ° C. for 2 hours. The dried product was further activated with carbon dioxide gas at 850 ° C. for 2 hours. The obtained activated carbon is defined as activated carbon [N5AC EX 1 + 2h] (Comparative Example 1). FIG. 1 shows a production flowchart of the activated carbon of Comparative Example 1.

(Comparative Example 2)
1 part by weight of activated carbon [N5AC EX 1 + 2h] was immersed in 100 parts by weight of a 0.1 mol / L aqueous sodium hydroxide solution at 25 ° C. for 25 hours, washed thoroughly with distilled water and dried to obtain activated carbon. Got. The obtained activated carbon is defined as activated carbon [N5AC EX 1 + 2h Na0.1N25C25hR100] (Comparative Example 2).

(Comparative Example 3)
1 part by weight of activated carbon [N5AC EX 1 + 2h] is immersed in 100 parts by weight of a 0.1 mol / L aqueous sodium hydroxide solution at 25 ° C. for 100 hours, washed thoroughly with distilled water and dried to obtain activated carbon. Obtained. The obtained activated carbon is referred to as activated carbon [N5AC EX 1 + 2h Na0.1N25C100hR100] (Comparative Example 3).

(Comparative Example 4)
1 part by weight of activated carbon [N5AC EX 1 + 2h] is immersed in 100 parts by weight of 1 mol / L aqueous sodium hydroxide solution at 25 ° C. for 100 hours, and then washed thoroughly with distilled water and dried to obtain activated carbon. It was. The obtained activated carbon is defined as activated carbon [N5AC EX 1 + 2h Na1N25C100hR100] (Comparative Example 4).

Example 1
1 part by weight of activated carbon [N5AC EX 1 + 2h] is immersed in 100 parts by weight of 1 mol / L aqueous sodium hydroxide solution at 80 ° C. for 100 hours, then washed thoroughly with distilled water and dried to obtain activated carbon. It was. The obtained activated carbon is referred to as activated carbon [N5AC EX 1 + 2h Na1N80C100hR100] (Example 1).

  Table 1 shows the pore characteristics, ash content, and packing density of the five types of activated carbon. The packing density was measured by tapping 100 times after putting a sample in a 10 mL measuring cylinder. The ash content was determined from the mass residual rate of approximately 50 mg of activated carbon sample heated to 950 ° C. in air. In addition, Table 1 also shows activated carbon (reference example) in which only sugar beet syrup is activated at 850 ° C. for 1 hour.

[Dip-type desulfurization test-1 using model oil]
As a model oil for kerosene, a solvent mixed at a ratio of 85% by mass of n-decane (C ₁₀ H ₂₂ ) and 15% by mass of tert-butylbenzene (C ₆ H ₅ -C— (CH ₃ ) ₃ ) was prepared. Benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (DMDBT) were added to this solvent so that each became 10 mass ppm-S, and it was set as the model oil A.

Activated carbon previously dried at 130 ° C. for 3 hours or more was immersed in model oil A in a 30 cm ³ glass container at a liquid-solid ratio shown in Table 2, and was immersed at 25 ° C. for 168 hours (one week). The glass container was stirred by hand once a day. After 168 hours, the supernatant of model oil A was collected, and BT, DBT, and DMDBT in model oil A were quantified with a gas chromatograph-mass spectrometer (GC-MS). The adsorption isotherm of each sulfur compound in the immersion type desulfurization test using model oil A containing BT, DBT, and DMDBT is shown in FIG.

  In the rice husk activated carbon subjected to the alkali treatment after the activation treatment, pores developed as the ash content decreased, and the adsorption ability of DBT and DMDBT, which are sulfur compounds to be adsorbed on the activated carbon, was improved. It can be seen that the adsorption capacity of BT is extremely low, and the adsorbent of the present invention adsorbs DBT and DMDBT almost selectively. Incidentally, the adsorption performance of BT was slightly improved by performing the alkali treatment.

  Compared to the activated carbon [N5AC EX 1 + 2h] (Comparative Example 1), the amount of DBT and DMDBT adsorbed on the activated carbon [N5AC EX 1 + 2h Na1N80C100hR100] (Example 1) per unit mass is the same as the equilibrium concentration. Doubled. For example, when the adsorption isotherm of DMDBT is compared at an equilibrium sulfur concentration of 1.0 mass ppm, the adsorption amount of activated carbon [N5AC EX 1 + 2h] (Comparative Example 1) is 0.9 mg-S / g-Ads. On the other hand, the adsorption amount of activated carbon [N5AC EX 1 + 2h Na1N80C100hR100] (Example 1) was 1.8 mg-S / g-Ads. The DMDBT adsorption amount of the activated carbon was almost proportional to the ultra micro pore volume.

When the alkali treatment was performed, the packing density decreased, but the activated carbon [N5AC EX 1 + 2h Na1N80C100hR100] (implemented for the packing density of 0.51 g / cm ^{3 of} activated carbon [N5AC EX 1 + 2h] (Comparative Example 1)) Since the packing density of Example 1) is 0.31 g / cm ^3, it is about 40% lower, and activated carbon [N5AC EX 1 + 2h Na1N80C100hR100] that has been subjected to alkali treatment per unit volume (capacity) (Example 1) ) Had higher adsorptive desulfurization performance.

[Dip-type desulfurization test-2 using model oil]
(Comparative Example 5 and Example 2)
As a model oil of light oil, only DMDBT is mixed with a solvent mixed at a ratio of 85% by mass of n-decane (C ₁₀ H ₂₂ ) and 15% by mass of tert-butylbenzene (C ₆ H ₅ -C— (CH ₃ ) ₃ ). Was added so that it might become 10 mass ppm-S, and it was set as model oil B. The activated carbons of Comparative Example 1 and Example 1 were activated carbon [N5AC EX 1 + 2h] (Comparative Example 5) and activated carbon [N5AC EX 1 + 2h Na1N80C100hR100] (Example 2), respectively. The experiment was conducted in the same manner as in the immersion type desulfurization test-1 using model oil. The adsorption isotherm of DMDBT is shown in FIG.

  Compared with activated carbon [N5AC EX 1 + 2h] (Comparative Example 5), the amount of DMDBT adsorbed on activated carbon [N5AC EX 1 + 2h Na1N80C100hR100] (Example 2) is about 2 when compared at the same equilibrium concentration per unit mass. Doubled.

<< Model oil immersion type desulfurization test for activated carbon activated after activated alkali treatment >>
[Preparation of activated carbon-2]
(Comparative Examples 6-7)
As with the alkali-treated activated carbon after the activation treatment, rice husks from Akita Komachi produced in Nishikimura, Akita Prefecture (currently Semboku City) in 2005 were used. The silica content was removed by elution using an aqueous sodium hydroxide solution from the carbonized rice husks before extrusion.

  The raw carbonized coconut shell was carbonized at 600 ° C. in a 1 mol / L sodium hydroxide aqueous solution at a liquid-solid ratio of 20 at 80 ° C. for 10 hours for alkali treatment. After cooling to room temperature, the carbide was recovered using filter paper. The carbide was thoroughly washed with distilled water and dried at 105 ° C. for 12 hours. Thereafter, 40 parts by mass of sugar sugar (dry basis) was added at 100 parts by mass of carbide, extruded at φ1.00 mm, and dried at 105 ° C. for 1 hour. The dried extrudate was carbonized for 5 minutes at 850 ° C. in nitrogen. The carbonized product was immersed in a sugar syrup for penetration and soaking for 12 hours. Thereafter, the molded product was removed from the syrup and dried at 105 ° C. for 2 hours. The dried product was activated at 850 ° C. to produce activated carbon. The activation treatment was performed under the conditions of only 0.5 hours in one stage and 0.25 hours and 0.5 hours in two stages. Activated carbon obtained by one-stage activation treatment is activated carbon [N5AC60 Na1N EX 0.5h] (Comparative Example 6), and activated carbon obtained by two-stage activation treatment is activated carbon [N5AC60 Na1N EX 0.25 + 0.5h] (Comparative Example 7). And

  FIG. 4 shows a production flowchart of activated carbon [N5AC60 Na1N EX 0.5h] (Comparative Example 6) and activated carbon [N5AC60 Na1N EX 0.25 + 0.5h] (Comparative Example 7). Here, the difference from the manufacturing process of activated carbon [N5AC EX 1 + 2h] (Comparative Example 1) shown in FIG. 1 is that a raw rice husk is pre-carbonized at 600 ° C. and immersed in an aqueous solution of sodium hydroxide to obtain silica. The point is to remove minutes.

(Example 3 and Comparative Example 8)
Next, the activated carbon [N5AC60 Na1N EX 0.5h] (Comparative Example 6) and the activated carbon [Comparative Example 6] except that the raw rice husk was pre-carbonized at 850 ° C. instead of the pre-carbonized raw rice husk at 600 ° C. N5AC60 Na1N EX 0.25 + 0.5h] (Comparative Example 7) was used to produce activated carbon. The obtained activated carbon is referred to as activated carbon [N5AC85 Na1N EX 0.5h] (Example 3) and activated carbon [N5AC85 Na1N EX 0.25 + 0.5h] (Comparative Example 8). FIG. 5 shows a production flow chart of activated carbon [N5AC85 Na1N EX 0.5h] (Example 3) and activated carbon [N5AC85 Na1N EX 0.25 + 0.5h] (Comparative Example 8).

(Examples 4 to 5)
Next, instead of the pre-carbonized ginger husk at 600 ° C., 100 parts by mass of sugar beet sugar (dry basis) was added to 100 parts by mass of the ginger husk pre-carbonized at 250 ° C., and carbonized at 600 ° C. Activated carbon was produced in the same manner as the above activated carbon [N5AC60 Na1N EX 0.5h] (Comparative Example 6) and activated carbon [N5AC60 Na1N EX 0.25 + 0.5h] (Comparative Example 7) except that the above was used. The obtained activated carbon is referred to as activated carbon [N5AC Na1N EX 0.5h] (Example 4) and activated carbon [N5AC Na1N EX 0.25 + 0.5h] (Example 5). FIG. 6 shows a production flow chart of activated carbon [N5AC Na1N EX 0.5h] (Example 4) and activated carbon [N5AC Na1N EX 0.25 + 0.5h] (Example 5).

  Table 3 shows the pore characteristics, ash content, and packing density of the six types of activated carbon.

[Dip-type desulfurization test-3 using model oil]
After the activation treatment, the immersion type desulfurization test using the model oil A was performed in the same manner as the alkali-treated activated carbon. FIG. 7 shows adsorption isotherms of each sulfur compound in the immersion desulfurization test using model oil A containing BT, DBT, and DMDBT.

  In the rice husk activated carbon that was molded and activated after the alkali treatment, as in the case of the alkali treated activated carbon after the activation treatment, the ash content decreased and pores developed, and the adsorption capacity of DBT and DMDBT was improved per unit mass. It can be seen that the adsorption capacity of BT is extremely low, and the adsorbent of the present invention adsorbs DBT and DMDBT almost selectively. Incidentally, the adsorption performance of BT was slightly improved by performing the alkali treatment.

  When compared at the same equilibrium concentration per unit mass, activated carbon [N5AC85 Na1N EX 0.5h] (Example 3) and activated carbon [N5AC] are compared to activated carbon [N5AC EX 1 + 2h] (Comparative Example 1) that is not subjected to alkali treatment. The adsorption amount of DBT and DMDBT of Na1N EX 0.5h] (Example 4) and activated carbon [N5AC Na1N EX 0.25 + 0.5h] (Example 5) was about doubled.

When the molding and activation treatment were performed after the alkali treatment, the decrease in packing density was less than when the alkali treatment was carried out after the activation treatment, and higher adsorptive desulfurization performance was obtained per unit volume (capacity). For example, the packing density of activated carbon [N5AC EX1 + 2h Na1N80C100hR100] (Example 1) was 0.31 g / cm ³ , but the packing density of activated carbon [N5AC Na1N EX 0.25 + 0.5h] (Example 5) was It was 0.47 g / cm ³ . Although the DMDBT adsorption performance per unit mass of both was the same, activated carbon [N5AC Na1N EX 0.25 + 0.5h] (Example 5) was about 1.5 times larger per unit volume (capacity).

[Preparation of activated carbon-3]
(Example 6)
Activated carbon [N5AC Na1N EX 0.5h] (Example 6) was prepared under the same conditions as the activated carbon [N5AC Na1N EX 0.5h] (Example 4) in order to examine the preparation method of the activated activated carbon after alkali treatment. .

(Comparative Example 9)
In the production process of activated carbon [N5AC Na1N EX 0.5h] (Example 6) (see FIG. 6), the dried extruded product was carbonized in nitrogen at 850 ° C. for 5 minutes, and then 1 part by mass of the carbonized product. Was immersed in 100 parts by mass of a 1 mol / L aqueous sodium hydroxide solution at 80 ° C. for 10 hours. And after washing | cleaning the immersion treatment material sufficiently with distilled water, after carbonizing for 15 minutes at 850 degreeC in nitrogen, Furthermore, 1 mass part of the treatment material was added to 100 mass parts of 1 mol / L sodium hydroxide aqueous solution, and 80 mass parts. It was immersed again at 10 ° C. for 10 hours. And the immersion treatment product was sufficiently washed with distilled water and dried to obtain activated carbon. The obtained activated carbon is referred to as activated carbon [N5AC Na1N EX Na1N N15min Na1N] (Comparative Example 9).

(Comparative Example 10)
In the production process of activated carbon [N5AC Na1N EX 0.5h] (Example 6) (see FIG. 6), the dried extruded product was carbonized in nitrogen at 850 ° C. for 5 minutes, and then 1 part by mass of the carbonized product. Was immersed in 100 parts by mass of a 1 mol / L aqueous sodium hydroxide solution at 80 ° C. for 10 hours. And after washing | cleaning the immersion treatment material sufficiently with distilled water, after carrying out activation processing at 850 degreeC for 5 minutes in a carbon dioxide, 1 mass part of processed material is added to 100 mass parts of 1 mol / L sodium hydroxide aqueous solution at 80 degreeC. Soaked again for 10 hours. And the immersion treatment product was sufficiently washed with distilled water and dried to obtain activated carbon. The obtained activated carbon is referred to as activated carbon [N5AC Na1N EX Na1N C5min Na1N] (Comparative Example 10).

(Example 7)
Activated carbon [N5AC Na1N EX 0.5h] (Example 6) was further subjected to additional activation treatment at 850 ° C. in carbon dioxide for 5 minutes. The obtained activated carbon is defined as activated carbon [N5AC Na1N EX 0.5h + 5min] (Example 7).

(Example 8)
Activated carbon [N5AC Na1N EX 0.5h] (Example 6) was further subjected to additional activation treatment at 850 ° C. for 15 minutes in carbon dioxide. The obtained activated carbon is referred to as activated carbon [N5AC Na1N EX 0.5h + 15min] (Example 8).

Example 9
Activated carbon [N5AC Na1N EX 0.5h] (Example 6) was further subjected to additional activation treatment at 850 ° C. for 45 minutes in carbon dioxide. The obtained activated carbon is referred to as activated carbon [N5AC Na1N EX 0.5h + 45min] (Example 9).

  Activated carbon [N5AC Na1N EX Na1N N15min Na1N] (Comparative Example 9), Activated carbon [N5AC Na1N EX Na1N C5min Na1N] (Comparative Example 10), Activated carbon [N5AC Na1N EX 0.5h + 5min] (Example 7), Activated carbon [N5AC Na1N Table 4 shows the pore characteristics, ash content and packing density of EX 0.5h + 15min] (Example 8) and activated carbon [N5AC Na1N EX 0.5h + 45min] (Example 9).

[Dip-type desulfurization test using model oil-4]
In addition to the model oil A of immersion desulfurization test -1 using a model oil, n- decane _{(C 10 H} 22) 85 wt%, tert-butyl benzene _{(C 6 H 5 -C- (CH} 3) 3) Model oil prepared by adding benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT) to a solvent mixed at a ratio of 15% by mass to 100 mass ppm-S. C was used. The immersion desulfurization test was conducted with the liquid-solid ratio of 20, 50, 100, and 200 for the model oil A, and with the liquid-solid ratio of 50 and 100 for the model oil C. The adsorption isotherm of each sulfur compound in the immersion type desulfurization test using model oil A and model oil C containing BT, DBT, and DMDBT is shown in FIG.

  Activated carbon [N5AC Na1N EX 0.5h] (Example 6), Activated carbon [N5AC Na1N EX 0.5h + 5min] (Example 7), Activated carbon [N5AC Na1N EX 0.5h + 15min] (Example 8) and Activated carbon [N5AC Na1N EX 0.5h + 45min] (Example 9) had higher adsorption performance than activated carbon [N5AC Na1N EX Na1N N15min Na1N] (Comparative Example 9) and activated carbon [N5AC Na1N EX Na1N C5min Na1N] (Comparative Example 10) . Since the activated carbon [N5AC Na1N EX Na1N N15min Na1N] (Comparative Example 9) and the activated carbon [N5AC Na1N EX Na1N C5min Na1N] (Comparative Example 10) have low ash content, it is understood that the desulfurization performance is not high as the ash content is low. . In particular, activated carbon [N5AC Na1N EX Na1N C5min Na1N] (Comparative Example 10) has the same specific surface area and lower ash content than activated carbon [N5AC EX 1 + 2h] (Comparative Example 1), but unit mass The hit performance did not improve. From these facts, it can be seen that it is important for the adsorption performance to leave an appropriate ash content and maintain a suitable pore structure.

[Preparation of activated carbon-4]
(Example 10)
Carbonization after adding sugar beet sugar in rice husk pre-carbonized at 250 ° C. under the preparation conditions of activated carbon [N5AC Na1N EX 0.5h] (Example 4) in order to examine the preparation method of activated activated carbon after alkali treatment Except for changing the temperature from 600 ° C. to 850 ° C., activated carbon was produced in the same manner as the activated carbon [N5AC Na1N EX 0.5h] (Example 4), and activated carbon [N5AC N1h Na1N EX 0.5h] (Example 10). ) Was prepared.

(Comparative Example 11)
In the production process of activated carbon [N5AC N1h Na1N EX 0.5h] (Example 10), the dried extruded product was carbonized in nitrogen at 850 ° C. for 5 minutes, and then 1 part by mass of this carbonized product was 1 mol / wt. It was immersed in 100 mass parts of L sodium hydroxide aqueous solution at 80 degreeC for 10 hours. And after washing | cleaning the immersion treatment material sufficiently with distilled water, after activating treatment for 2 minutes at 850 degreeC in a carbon dioxide, 1 mass part of activation treatment products are made into 100 mass parts of 1 mol / L sodium hydroxide aqueous solution, and 80 mass parts. It was immersed again at 10 ° C. for 10 hours. And the immersion treatment product was sufficiently washed with distilled water and dried to obtain activated carbon. The obtained activated carbon is referred to as activated carbon [N5AC N1h Na1N EX Na1N C2min Na1N] (Comparative Example 11).

(Example 11)
Activated carbon [N5AC N1h Na1N EX 0.5h] (Example 10) was further subjected to additional activation treatment at 850 ° C. for 15 minutes in carbon dioxide. The obtained activated carbon is referred to as activated carbon [N5AC N1h Na1N EX 0.5h + 15min] (Example 11).

(Example 12)
Activated carbon [N5AC N1h Na1N EX 0.5h] (Example 10) was further subjected to additional activation treatment at 850 ° C. in carbon dioxide for 45 minutes. The obtained activated carbon is referred to as activated carbon [N5AC N1h Na1N EX 0.5h + 45min] (Example 12).

  Activated carbon [N5AC N1h Na1N EX 0.5h] (Example 10), activated carbon [N5AC N1h Na1N EX Na1N C2min Na1N] (Comparative Example 11), activated carbon [N5AC N1h Na1N EX 0.5h + 15min] (Example 11) and activated carbon [Example 11] Table 5 shows the pore characteristics, ash content and packing density of N5AC N1h Na1N EX 0.5h + 45 min] (Example 12).

[Dip-type desulfurization test using model oil-5]
Similarly to the immersion type desulfurization test -4 using model oil, the adsorption isotherm of each sulfur compound in the immersion type desulfurization test using model oil A and model oil C including BT, DBT, and DMDBT is shown in FIG.

  Activated carbon [N5AC N1h Na1N EX 0.5h] (Example 10), activated carbon [N5AC N1h Na1N EX 0.5h + 15min] (Example 11) and activated carbon [N5AC N1h Na1N EX 0.5h + 45min] (Example 12) The adsorption performance was higher than that of activated carbon [N5AC N1h Na1N EX Na1N C2min Na1N] (Comparative Example 11). Since activated carbon [N5AC N1h Na1N EX Na1N C2min Na1N] (Comparative Example 11) has a low ash content, it can be seen that the less the ash content, the higher the desulfurization performance. Activated carbon [N5AC N1h Na1N EX Na1N C2min Na1N] (Comparative Example 11) is equivalent to activated carbon [N5AC EX 1 + 2h] (Comparative Example 1) and has a smaller specific ash content, but per unit mass The performance did not improve. From these facts, it can be seen that it is important for the adsorption performance to leave an appropriate ash content and maintain a suitable pore structure.

<< Commercial kerosene immersion type desulfurization test for alkali-treated activated carbon after activation treatment >>
[Activated carbon]
Activated carbon [N5AC EX 1 + 2h] (Comparative Example 1), activated carbon [N5AC EX 1 + 2h Na1N80C100hR100] (Example 1), activated carbon [N5AC] Na1N EX 0.5h + 15min] (Example 8) and activated carbon [N5AC Na1N EX 0.5h + 45min] (Example 9) are the same activated carbon [N5AC EX 1 + 2h] (Comparative Example 12), activated carbon [ N5AC EX 1 + 2h Na1N80C100hR100] (Example 13), activated carbon [N5AC Na1N EX 0.5h + 15min] (Example 14) and activated carbon [N5AC Na1N EX 0.5h + 45min] (Example 15) were used.

[Immersion desulfurization test using commercial kerosene]
Activated carbon [N5AC EX 1 + 2h] (Comparative Example 12), Activated carbon [N5AC EX 1 + 2h Na1N80C100hR100] (Example 13), Activated carbon [N5AC Na1N EX 0.5h + 15min] (Example 14) and Activated carbon [N5AC Na1N EX 0.5h + 45min] (Example 15) was used, and an immersion type desulfurization test in kerosene was performed.

  Kerosene (manufactured by Japan Energy) has a boiling range of 158.0 to 271.5 ° C, a 5% distillation point of 170.5 ° C, a 10% distillation point of 175.5 ° C, a 20% distillation point of 183.0 ° C, 30% distillation point 190.0 ° C, 40% distillation point 197.5 ° C, 50% distillation point 206.0 ° C, 60% distillation point 215.0 ° C, 70% distillation point 224.0 ° C, 80% distillation point 234.0 ° C, 90% distillation point 248.0 ° C, 95% distillation point 259.5 ° C, 97% distillation point 269.0 ° C, density (15 ° C) 0.7940 g / ml , Aromatic content 16.9 vol%, saturation content 83.1 vol%, sulfur content 6.7 mass ppm, among the sulfur content, dibenzothiophenes (heavier than 4-methyldibenzothiophene and 4-methyldibenzothiophene) Sulfur compounds derived from heavy sulfur compounds having a molecular weight of 198 or more) Nitrogen content of 1 mass ppm or less was used ones.

  After setting the mass ratio (liquid / solid ratio) of kerosene to each activated carbon to 30, 120 and 240, the activated carbon was immersed in kerosene and allowed to stand at 10 ° C. for 10 days or more to obtain a sufficiently adsorption equilibrium state. Kerosene was removed. By analyzing by GC-ICP-MS, the concentration of sulfur derived from dibenzothiophenes was determined.

  FIG. 10 shows an adsorption isotherm of dibenzothiophenes in an immersion desulfurization test using commercial kerosene.

  The activated rice husk activated carbon [N5AC EX 1 + 2h Na1N80C100hR100] (Example 13) is similar to the model oil in the case of commercial kerosene, and the adsorptive desulfurization performance of dibenzothiophenes per unit mass is similar to that of model oil. This was about twice that of activated carbon [N5AC EX 1 + 2h] (Comparative Example 12). Although the packing density was reduced by about 40%, the activated carbon [N5AC EX 1 + 2h Na1N25C100hR100] (Example 13) subjected to alkali treatment per unit volume (capacity) had higher adsorptive desulfurization performance. Furthermore, activated carbon [N5AC Na1N EX 0.5h + 15min] (Example 14) and activated carbon [N5AC Na1N EX 0.5h + 45min] (Example 15) are obtained from activated carbon [N5AC EX 1 + 2h Na1N80C100hR100] (Example 13). In addition to its high desulfurization performance, the packing density was also high.

  When the mass ratio (liquid-solid ratio) of activated carbon [N5AC Na1N EX 0.5h + 15min] (Example 14) and activated carbon [N5AC Na1N EX 0.5h + 45min] (Example 15) is 30, the polycyclic aromatic component Was compared with raw material kerosene. Aromatic content is based on British Institute of Petroleum standard IP standard method 391/95 (analysis of aromatic hydrocarbons in middle distillates by high performance liquid chromatograph using refractive index detector). It was measured. The results are shown in Table 6. It can be seen that the polycyclic aromatic component is removed by adsorption.

〔Test method〕
The physical properties of activated carbon, model oil, and kerosene, which are not specifically described above, were measured according to the following test method.
Distillation property: Measured according to JIS K2254.
Density (15 ° C.): Measured according to JIS K2249.
Hydrocarbon component composition (aromatic content, saturated content, olefin content): Measured according to JPI-5S-49-97.
Sulfur content (total sulfur content): analyzed by combustion oxidation-ultraviolet fluorescence method.
Sulfur compound type analysis (sulfur content in fractions lighter than benzothiophene, benzothiophenes, dibenzothiophenes): Analyzed by GC-ICP-MS.
Nitrogen content: Measured according to the microcoulometric titration method described in JIS K2609.
-Alumina content: An alkali-melted sample was dissolved in an acidic solution and analyzed with ICP-AES (inductively coupled plasma emission spectrometer).
Specific surface area: measured by a nitrogen adsorption method and calculated by a BET (Brunouer-Emmett-Teller) method.
-Pore volume: measured by a nitrogen adsorption method.

Claims (15)

The specific surface area Sa is 800 to 4,000 m ² / g, the total pore volume Va is 0.5 to 1.2 cm ³ / g, and the ash content is 3 to 10% by mass. Characteristic activated carbon. The activated carbon according to claim 1, wherein an average pore width d obtained by the following formula (I) is 1.0 to 2.0 nm.
d = 2000 × Va / Sa (I) 2. The activated carbon according to claim 1, wherein the mesopore volume Vm having a pore width of 2.0 nm or more and less than 50 nm is 0.1 to 0.5 cm ³ / g.   The activated carbon according to claim 3, wherein the ratio Vm / Va of the mesopore volume Vm to the total pore volume Va is 0.2 to 0.5.   The ratio Vu / Vs of the ultra micro pore volume Vu having a pore width of less than 0.7 nm to the super micro pore volume Vs having a pore width of 0.7 nm or more and less than 2.0 nm is 1.0 to 2.5. The activated carbon according to claim 1, wherein A method for producing activated carbon comprising a step of carbonizing and activating a raw material containing 40% by mass or more of rice husk,
Furthermore, the process of removing the ash content of the said activated carbon by alkali treatment is included, The manufacturing method of the activated carbon in any one of Claims 1-5 characterized by the above-mentioned.   A carbonized material is obtained by carbonizing a raw material containing rice husks of 40% by mass or more, and after the ash is removed by subjecting the carbonized product to an alkali treatment, the carbonized product is activated. 6. The method for producing activated carbon according to 6.   The method for producing activated carbon according to claim 7, wherein the carbonized product is molded after the alkali treatment.   A liquid characterized by adsorbing and removing a trace component contained in the liquid by contacting the liquid with an adsorbent comprising the activated carbon according to claim 1 or an adsorbent containing the activated carbon. Purification method.   The method for purifying a liquid according to claim 9, wherein the liquid is kerosene or light oil.   The method for purifying a liquid according to claim 9 or 10, wherein the trace component is an aromatic compound.   The method for purifying a liquid according to claim 11, wherein the aromatic compound is at least one sulfur compound selected from the group consisting of benzothiophenes and dibenzothiophenes.   The method for purifying a liquid according to claim 12, wherein as a post-treatment in the step of bringing the adsorbent into contact with the liquid, a sulfur compound is adsorbed and removed using a solid acid adsorbent.   The method for purifying a liquid according to any one of claims 9 to 13, wherein the adsorbent and the liquid are contacted at a temperature of 0 to 80 ° C.   A fuel cell system using the liquid purification method according to claim 9.

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