JP2005194132A - Method for heating activated carbon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for heating activated carbon, by which a solvent or gas adsorbed by the activated carbon can be easily and stably desorbed and recovered without using steam; and to provide a method for recovering the solvent using the same. <P>SOLUTION: In the case when the surface of the activated carbon is heated by irradiation with microwave or the like after covering the surface of the activated carbon with a heat resistant, insulative covering material having a thickness of ≥0.0005 and ≤1.0 mm, the temperature of the activated carbon itself can be uniformly raised easily in a short time without causing spark discharge and accordingly causing combustion of the activated carbon even when the surface is irradiated with microwave or the like in an atmosphere containing oxygen. Since this method can be carried out even in a small scale apparatus, it becomes possible to recover solvents volatilized in air, in small scale business places handling solvents, such as dry cleaning stores or painting stores. It is applicable also to pyrogenetic reaction using activated carbon catalist. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for heating activated carbon by irradiating the activated carbon whose surface is coated with a heat-resistant and electrically insulating coating material with microwaves or applying a high frequency. Further, the present invention relates to a method for recovering the adsorbed solvent or gas by heating the activated carbon by a simple method after adsorbing the solvent or gas using the coated activated carbon. Furthermore, it is related with the catalytic reaction method which applied the heating method of this activated carbon.

  In factories that handle a large amount of solvent, a method is widely used in which a volatilizing solvent is adsorbed on activated carbon and later desorbed and recovered. However, the method of desorbing the adsorbed solvent is generally a steam heating method, and requires a boiler, a condenser, a decanter, and the like. In addition, separation of the desorbed solvent and water is difficult, and the solvent recovery apparatus becomes large, resulting in high equipment costs and running costs. For this reason, small-scale establishments that handle solvents, such as dry cleaning shops and paint factories, are not equipped with much solvent recovery devices, and the present situation is that a part of the solvent is diffused into the atmosphere. Activated carbon is also used for gas purification, malodorous gas, and adsorption and removal of toxic gases, but heating the activated carbon that has adsorbed these gases causes the same situation as in the case of solvents. Exists.

  Activated carbon is used as a catalyst for various chemical reactions or as a catalyst carrier. In general, the catalytic reaction often requires heating. In this case, it is necessary to heat the gas to be processed and the entire apparatus with a large apparatus, and a large amount of energy is consumed.

Instead of desorbing the solvent or gas from the activated carbon that has adsorbed the solvent or gas with water vapor, the activated carbon is directly irradiated with microwaves or the activated carbon is heated to desorb the adsorbed solvent or gas. Can be considered. However, activated carbon is prone to electrical breakdown, and there is a major problem in that when a microwave is irradiated, a discharge phenomenon occurs and sparks fly, and the activated carbon ignites, burns, and explodes.
In order to prevent this, a method of circulating an inert gas through a layer filled with activated carbon has been proposed (Patent Document 1). However, in this method, heating cannot be performed uniformly, and it is necessary to replace the entire inside of the apparatus with an inert gas, so that there is a problem that the apparatus becomes heavy and large, and the cost increases.

In Patent Document 2, a proposal has been made to reduce the number of contact points between activated carbons by suppressing the generation of sparks by mixing and pressing activated carbon and a non-conductive substance or covering the outer surface of the activated carbon with a non-conductive substance. In Examples, activated carbon and zeolite are mixed at a ratio of 7: 3 and pressed. However, the pellets obtained by this method are not practical as they are because the heating efficiency of activated carbon by microwaves is low and the amount of adsorption / desorption of solvent vapor and the like is extremely small. That is, it is not clear how and how the non-conductive substance is combined with the activated carbon, and no practical adsorbent having a good balance between adsorption performance and performance capable of microwave heating has been proposed.
JP-A-6-31163 Japanese Patent No. 3044279

  Therefore, if the solvent can be desorbed and recovered from the activated carbon by a simple method without using water vapor, it will be possible to recover the solvent with simple equipment even in a small-scale office, which should lead to prevention of air pollution. The present invention intends to provide a heating method of activated carbon that can safely and easily desorb and recover the solvent and gas adsorbed on the activated carbon without using water vapor, and a solvent recovery method using the method. It is. Furthermore, the present invention also provides a method for safely and efficiently regenerating activated carbon used for gas purification, odor gas and harmful gas removal.

  In addition, in a catalytic reaction apparatus using activated carbon, if the activated carbon can be efficiently heated and heated, energy-saving operation by a small facility becomes possible. The present invention provides a catalytic reaction method using activated carbon which can heat and raise the temperature of activated carbon itself as a catalyst safely and efficiently.

  As a result of intensive studies on an adsorbent for solvent recovery by microwave heating or the like, the present inventors coated the surface of activated carbon with a heat-resistant and electrically insulating coating material to a specific thickness, and the activated carbon particles As a result of avoiding direct contact, the original solvent adsorption performance of the activated carbon does not deteriorate, and even if this coated activated carbon is irradiated with microwaves in the air (in the presence of oxygen), no spark discharge occurs, Accordingly, it has been found that the activated carbon can be heated to the target temperature safely and easily and efficiently within a short time without ignition and combustion.

That is, the present invention
(1) A method of heating activated carbon in which activated carbon coated with a heat-resistant and electrically insulating coating material with a thickness of 0.0005 mm or more and 1.0 mm or less is irradiated with microwaves or applied with a high frequency,
(2) The method for heating activated carbon according to (1), wherein the coating material is a heat-resistant coating material that is physically and chemically stable at 200 ° C. or lower,
(3) The method for heating activated carbon according to (1) or (2), wherein the coating material is an electrically insulating coating material having an electrical resistivity of 1 Ωm or more,
(4) The method for heating activated carbon according to (1), wherein the ash content in the activated carbon is 15% by weight or less,
(5) The shape of the activated carbon covered with the coating material is granular, the average particle diameter is 0.1 mm or more and 20 mm or less, and the coating material is powder and the average particle diameter is 0.1 μm or more, The method for heating activated carbon according to (1), which is 100 μm or less,
(6) The method for heating activated carbon according to any one of (1) to (3), wherein the coating material is an inorganic oxide, clay mineral, or ferrite compound,
(7) The method for heating activated carbon according to (1), wherein the coating material particles are fixed to the surface using water glass,
(8) Activated carbon coated with a heat-resistant and electrically insulating coating material with a thickness of 0.0005 mm or more and 1.0 mm or less is packed in a packed tower, adsorbed with solvent or gas, and then irradiated with microwaves or high frequency And a solvent recovery method for desorbing the adsorbed solvent or gas by heating, and (9) a catalyst coated with a heat-resistant and electrically insulating coating material with a thickness of 0.0005 mm or more and 1.0 mm or less. Activated carbon which may carry a component, after filling the reactor, irradiation with microwaves or application of high frequency and heating, the catalytic reaction method to promote the reaction,
It is.

Many techniques have been reported so far for coating activated carbon surfaces with various substances and imparting new physical properties and functions, but most of them are aimed at improving hydrophilicity and suppressing the generation of fine powder. There were few things for the purpose of heating by microwave etc. like invention, solvent collection | recovery, and heating catalyst reaction promotion.
There is an example in which hydrophobic zeolite is mixed with activated carbon and microwaves are applied to the formed adsorbent and heated. However, in such a method, it is difficult to efficiently coat the surface of the activated carbon uniformly. The most important point of this heating method is how to uniformly coat the activated carbon surface without impairing the adsorption performance of the activated carbon itself.

  When the coated activated carbon of the present invention is used, if a microwave irradiation device or a high-frequency application device and a simple condenser are used, a solvent or gas can be recovered by heating or a catalytic reaction can be performed even with a small-scale device. There is no need to replace with active gas. In addition, since the adsorption performance of activated carbon is small, the apparatus does not become large.

The activated carbon used in the present invention has a coating having heat resistance and electrical insulation on the surface thereof, such as inorganic substances such as silica, alumina, titania, talc, montmorillonite, or resins such as fluororesin, phenol resin, polyester resin, etc. Activated carbon coated with a material. In the case of activated carbon with no coating, partial heating may occur, the temperature rise may not be stable, spark discharge may occur, and the activated carbon itself may ignite and burn. In contrast, the coated activated carbon used in the present invention can maintain a uniform and stable temperature rise according to the output of microwave irradiation. If this property is used, the solvent can be safely and easily desorbed from the activated carbon adsorbed with the solvent.
When heating by applying a high frequency, the coating material is preferably a magnetic material.

  The activated carbon used in the present invention may be any activated carbon suitable for solvent and gas recovery and heat catalytic reaction. However, if the amount of ash contained in the activated carbon is large, the calorific value when adsorbing the solvent is large and the ignition point is lowered, so that the amount of ash contained in the activated carbon is preferably 15% by weight or less, preferably 10% by weight or less. More preferred are those with 7% or less. The activated carbon having a low ash content can be obtained by using a raw material with low ash content or by washing the raw material of activated carbon or activated carbon with an aqueous solution containing an acid such as water or hydrochloric acid.

  The raw materials for activated carbon are plant fruits (such as palm husk and candle nut husk), coal (brown coal, bituminous coal, anthracite, etc.), pitch, tar, wood flour (such as sawdust), and synthetic resins (phenol resin, vinylidene chloride resin, etc.) Anything that is generally used can be used. Of these, fruits, particularly those derived from coconut shells, and coals, particularly those derived from bituminous coal, are preferred in terms of stable supply and performance.

The activation method is not particularly limited. For example, activated charcoal activated by an active gas such as water vapor, oxygen, carbon dioxide gas, phosphoric acid, zinc chloride manufactured by the method of “activated carbon industry, heavy chemical industry communication company (1974), p.23-p.37” Activated carbon such as chemical activated charcoal using etc. is used. The BET specific surface area of the activated carbon as a raw material is 500 to 2500 m ² / g, preferably 700 to 2000 m ² / g, and most preferably 800 to 1800 m ² / g.

  The particle size of the activated carbon is not particularly limited, but the average particle size is usually 0.1 mm or more and 20 mm or less from the viewpoint of pressure loss and adsorption speed when gas is passed when filling the apparatus. Is used. Preferably they are 0.3 mm or more and 10 mm or less mm, More preferably, they are 0.5 mm or more and 5 mm or less.

The activated carbon to be coated is formed into a crushed shape or a molded body (columnar shape, spherical shape, etc.). The molding may be performed by molding powdered activated carbon into a predetermined shape, or by activating a previously molded raw material into activated carbon. Of these, spherical ones are particularly preferable because the substance to be coated is easily coated on the activated carbon surface with a uniform thickness.
In order to form the activated carbon into a spherical shape, a rolling granulator or the like may be used, and there are methods such as spheroidizing what is extruded into a pellet form with an apparatus such as a Malmerizer.

The heat-resistant and electrically insulating coating material used in the present invention is a material that does not ignite at 200 ° C. or less, is physically and chemically stable without undergoing a heat change, and is unlikely to cause electrical breakdown, that is, electrical insulation. If it is a body. More specifically, at a temperature of 200 ° C. or less, it has heat resistance that does not ignite and is not subject to thermal change, and has an electrical resistivity (volume resistivity) of 1 Ωm or more, preferably 10 ³ Ωm or more, and more preferably Is 10 ⁵ Ωm or more. Among the specific examples of the coating agent, inorganic substances include alumina (electric specific resistance of about 10 ¹² Ωm), silica (electric specific resistance of about 10 ¹⁰ Ωm), zirconia (electric specific resistance of about 10 ¹² Ωm), titania. (Electric specific resistance of about 10 ¹¹ Ωm), iron oxide (electric specific resistance of about 10 ¹¹ Ωm), inorganic oxides such as calcium oxide (electric specific resistance of about 10 ¹⁰ Ωm), iron nickel ferrite (electric specific resistance of about 10 ¹⁰ Ωm) ), iron zirconium ferrite (electrical resistivity of about 10 ³ [Omega] m), nickel-zinc ferrite (electrical resistivity of about ^{10 10} [Omega] m) soft ferrite, yttrium iron garnet (electrical resistivity of about ^{10 10} [Omega] m) garnet ferrite such as such as ferrite compounds such as, an alloy such as iron chrome, single metals such as nickel (electrical resistivity of about 10 ⁹ [Omega] m), more kaolin Electrical resistivity of about ^{10 11} [Omega] m), talc (electrical resistivity of about ^{10 12} [Omega] m), sepiolite (electrical resistivity of about ^{10 11} [Omega] m), bentonite (electrical resistivity of about ^{10 11} [Omega] m) clay minerals, such as soda-lime glass ( Examples thereof include glasses such as electric specific resistance of about 10 ¹¹ Ωm), water glass (electric specific resistance of about 10 ¹⁰ Ωm), and borosilicate glass (electric specific resistance of about 10 ¹³ Ωm). Examples of organic substances include fluorine resin (electrical resistivity of about 10 ¹⁵ Ωm), phenolic resin (electrical resistivity of about 10 ¹¹ Ωm), polyester resin (electrical resistivity of about 10 ¹¹ Ωm), and vinyl chloride resin (electrical resistivity of about 10 ¹¹ Ωm). 10 ¹³ Ωm) and vinylidene chloride resin (electric specific resistance of about 10 ¹³ Ωm). You may use a coating | covering material individually or in combination of multiple. Of these, inorganic substances are preferred.

The average particle diameter of the particles of the coating material is not particularly limited, but if it is too small, it will cause clogging of the pores of the activated carbon, and if it is too large, the coating thickness will become too large. For this reason, 0.1 micrometer or more and 100 micrometers or less are preferable. More preferably, they are 0.5 micrometer or more and 50 micrometers or less, Most preferably, they are 1 micrometer or more and 30 micrometers or less.
The amount of the coating material used depends on the specific gravity, particle diameter, etc. of the activated carbon or the coating material, but on a dry basis, (weight of activated carbon): (total weight of the coating material is 100: 1 to 2: 1, preferably 100: 5 to 3: 1.

The thickness of the coating layer is important in the present invention. If the coating layer is thin, a spark discharge will occur when heated by microwaves, causing a fire or explosion. If the coating layer is too thick, the ratio of activated carbon per unit volume of the adsorption layer will decrease, and the adsorption performance and adsorption of solvents etc. The speed will drop. Therefore, the thickness of the coating layer is 0.0005 mm or more and 1.0 mm or less, more preferably 0.001 mm or more and 0.5 mm or less, and most preferably 0.005 mm or more and 0.1 mm or less.
Further, the thickness of the coating layer satisfies 1.002 ≦ (R ₂ / R ₁ ) ≦ 1.30, where R _{1 is} the particle size of the activated carbon before coating and R ₂ is the particle size of the activated carbon after coating with the coating material. It is preferable to satisfy 1.005 ≦ (R ₂ / R ₁ ) ≦ 1.25.

  As a method for coating the surface of the activated carbon with the coating material, a known method is used. For example, it is difficult to penetrate the coating material into the pores of the activated carbon, and the coating material is diluted with a solution of an appropriate binder that covers the activated carbon particles by adhering the coating material to the surface of the activated carbon, and the activated carbon is immersed in this and dried ( Impregnation method), a method of spraying and drying the solution containing the coating material on the surface of the activated carbon (spraying method), and a method of passing the solution containing the coating material and drying in a state where the activated carbon is fluidized (flow method). Etc. The coating material may also serve as a binder function, but generally other binders and viscosity modifiers are mixed. Although the surface of the activated carbon particles is coated with the coating material by this coating operation, the activated carbon particles do not enter the pores and have little influence on the entry and exit of the solvent and the like.

In contrast, when dissolved ions and ultrafine particles (molecular level) are dispersed in a solution that easily penetrates into activated carbon pores and supported by impregnation, etc., ions and ultrafine particles are placed inside the pores. Also penetrates and adheres to the inner wall, but the entire surface of the activated carbon particles is not covered.
The term “coating” in this case refers to fixing to the activated carbon surface, not fixing to the inside of the activated carbon pores as supported.

  There are organic and inorganic binders and viscosity modifiers. Examples of the organic binder and viscosity modifier include latex resins such as polyurethane, polystyrene, and vinylidene chloride. Examples of the inorganic binder include water glass (sodium silicate) and silica alumina ceramics. Among these, water glass is particularly preferable.

  Moreover, the coating material, the binder, and the viscosity modifier may each be one kind or two or more kinds. The use amount of the binder and the viscosity modifier is 1 to 20 parts by weight, preferably 5 to 10 parts by weight with respect to 100 parts of the coating material in the case of organic substances. However, inorganic substances such as water glass and silica-alumina ceramics themselves serve as a coating, so the amount is 1 to 300 parts by weight, preferably 5 to 200 parts, based on 100 parts of the coating material.

  The microwave is an electromagnetic wave having a wavelength of 0.1 mm to 1 m, and any microwave having a wavelength of 300 MHz to 300 GHz can be used for convenience. Among them, a microwave of 2.45 GHz and 500 W is easily available. The high frequency to be applied has a wavelength of 1 kHz to 10 MHz, preferably 10 kHz to 1 MHz.

A method for recovering an organic solvent adsorbed by activated carbon using the present invention will be described. The solvent is adsorbed onto the activated carbon by passing a gas containing the solvent through a tower packed with activated carbon coated with a coating material. The activated carbon is irradiated with microwaves or the like after the solvent is adsorbed until the activated carbon is in an adsorption breakthrough state or until the solvent leaks from the activated carbon layer outlet. The coated activated carbon in the packed bed is heated by heating the activated carbon by irradiation with microwaves or the like, and the temperature rises. However, since the activated carbon particles are not in direct contact, there is no ignition or combustion. The solvent adsorbed by heating is desorbed from the activated carbon, and the activated carbon is regenerated. The desorbed solvent is condensed and recovered by the condenser. At this time, since the conventional steam is not used, the recovery of the solvent becomes very easy and the apparatus can be miniaturized. Further, separation from a large amount of water is unnecessary, and a solvent dissolved in a minute amount is not mixed in the waste water.
When water is also adsorbed in the activated carbon, water is also released at the same time, but the amount is small and separation is easy.

  The irradiation amount of microwaves and the like is determined so as to be equal to or higher than the temperature at which the adsorbed substance is desorbed from the activated carbon. Usually, the temperature required for desorption is 120 ° C. or higher. This temperature can be controlled by the amount of microwave irradiation. At this temperature, moisture adsorbed together with the solvent is also desorbed, which is preferable for the regeneration of activated carbon. The upper limit of the temperature when heating is the temperature at which the activated carbon does not burn, and it is usually desirable to keep it below about 400 ° C. The packed tower may be a fixed bed, a moving bed or a fluidized bed.

  The solvent to be recovered is not particularly limited as long as it can be adsorbed by activated carbon. For example, aliphatic hydrocarbons such as gasoline, petroleum, kerosene, kerosene, mineral spirits, naphtha, pentane, hexane, heptane, octane, for example, aromatic hydrocarbons such as benzene, toluene, xylene, for example, 1,3-dichloro Propene, dichloromethane, chloroform, 1,2-dichloroethane, 1,1-dichloroethylene, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, Volatile organic chlorine compounds such as trichlorethylene, tetrachloroethylene, carbon tetrachloride, for example, ketones such as acetone, ethyl methyl ketone, diethyl ketone, isobutyl methyl ketone, cyclohexane, such as methyl acetate, ethyl acetate, propyl acetate, Esters such as methyl acid, ethyl formate, and propyl formate, for example, ethers such as diethyl ether, isopropyl ether, furfural, tetrahydrofuran, and dioxane, such as alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, and butyl alcohol Can be mentioned.

  The method of the present invention can be applied not only to recovering a solvent, but also to regenerating activated carbon used for gas purification or the like. For example, methane fermentation gas from natural gas, propane gas, and sludge contains hydrocarbons with a high boiling point, and activated carbon is used to remove them. Can be played easily. In addition, when activated carbon is used to remove other malodorous gases and harmful gases, the used activated carbon can be regenerated in the same manner.

Next, a method for heating the catalytic reaction apparatus using the heating method of the present invention will be described.
First, the activated carbon is charged into the catalytic reactor. In this case, a catalyst metal previously supported on activated carbon is used as necessary. The catalytic metal may be supported after being coated, but it is desirable to be supported on activated carbon before coating with the coating material. Reactants are circulated through the catalytic reactor. At this time, microwaves are irradiated and heated to a temperature suitable for the reaction. Only activated carbon can be efficiently heated by such a method, resulting in an energy-saving and small reactor.

  The method of heating activated carbon having the surface of the present invention coated with a heat-resistant and insulating coating material to a thickness of 0.0005 mm or more and 1.0 mm or less by microwave irradiation or the like is performed in an atmosphere containing oxygen. Since no spark discharge occurs even when irradiated, the activated carbon does not burn, and the temperature of the activated carbon itself can be raised to the target temperature easily and uniformly within a short time.

  Hereinafter, the present invention will be described with reference to Examples, Comparative Examples, and Experimental Examples, but the present invention is not limited to these.

Water glass diluted with water at the ratio shown in Table 1 (Wako Pure Chemicals, sodium silicate: electrical resistivity of about 10 ¹⁰ Ωm) and alumina (catalyst conversion, electrical resistivity of about 10 ¹² Ωm); average particle size 10 μm) was dispersed. Spherical activated carbon (Nippon Enviro Chemicals Co., Ltd. Spherical Coal XS-7100; average particle size 1.0 mm; ash content 3 wt%; electrical resistivity 10 ⁻⁵ Ωm while rolling with a rolling granulator, alumina / water glass solution Was sprayed for 30 minutes to coat the activated carbon surface, which was then dried sufficiently at 115 ° C. to obtain a sample of coated activated carbon.

  With the composition described in Example 2 in Table 1, the surface of the activated carbon was coated in the same manner as in Example 1 to obtain coated spherical activated carbon.

  In the same manner as in Example 1 with the composition described in Example 3 in Table 1, the surface of the activated carbon was coated to obtain coated spherical activated carbon.

  In the same manner as in Example 1 with the composition described in Example 4 in Table 1, the surface of the activated carbon was coated to obtain coated spherical activated carbon.

  With the composition described in Example 5 in Table 1, the surface of the activated carbon was coated in the same manner as in Example 1 to obtain coated spherical activated carbon.

  With the composition described in Example 6 in Table 1, the surface of the activated carbon was coated in the same manner as in Example 1 to obtain coated spherical activated carbon.

In the same manner as in Example 1 with the composition described in Example 7 of Table 1, a solution in which nickel zinc ferrite (synthetic product, electrical specific resistance of about 10 ¹⁰ Ωm) is dispersed in water glass diluted with water is prepared. The surface of spherical activated carbon was coated.

In the same manner as in Example 1 with the composition described in Example 8 of Table 1, a solution in which nickel zinc ferrite (synthetic product, electrical specific resistance of about 10 ¹⁰ Ωm) is dispersed in water glass diluted with water is prepared. The surface of spherical activated carbon was coated.
[Comparative Example 1]

A sample with a coating layer thickness that was too thin was prepared in the same manner as in Example 1 with the composition described in Comparative Example 1 of Table 1.
[Comparative Example 2]

A sample with a coating layer thickness that was too thin was prepared in the same manner as in Example 1 with the composition described in Comparative Example 2 of Table 1.
[Comparative Example 3]

  A sample having an excessively thick coating layer was prepared in the same manner as in Example 1 with the composition described in Comparative Example 3 of Table 1.

Of the activated carbons (original coals) used in the above examples, XL-7100 has an average particle diameter of 2.5 mm; an ash content of 3 wt%; an electrical resistivity of 10 ⁻⁵ Ωm, and spherical activated carbon (manufactured by Nippon Enviro Chemicals Co., Ltd.). ), X-7100 is a spherical activated carbon (manufactured by Nippon Enviro Chemicals Co., Ltd.) having an average particle size of 1.3 mm; an ash content of 3 wt%; and an electric resistivity of 10 ⁻⁵ Ωm. The bead charcoal is manufactured by Kureha Chemical Industry Co., Ltd .; average particle size 0.7 mm; ash content 0.5 wt%; electrical resistivity about 10 ⁻⁵ Ωm.
[Experimental Example 1]

High-frequency heating test A coil with an inner diameter of 30 mm was wound with a water-cooled copper tube (winding density: 200 m ⁻¹ , 210 windings), and a Pyrex test tube with an inner diameter of 11 mm was placed in the center. The test tube was filled with activated carbon with a thin coating thickness of Comparative Example 2 to a filling height of about 1.5 cm. A fluorescent optical fiber type temperature sensor was placed in the center of the activated carbon, and a high frequency of 56 kHz and 1 kW was applied to the coil while monitoring the temperature.
Next, in the same manner, the magnetic material-coated activated carbon of Example 7 was filled in a test tube, and a high frequency was applied. The results of both are summarized in FIG. In the case of activated carbon with a small coating thickness, the temperature hardly increases even after 15 minutes or more, whereas in the case of magnetic material-coated activated carbon, the temperature rises to about 140 ° C. in 3 minutes and is then stably maintained at that temperature. It was. At this time, no spark discharge was observed.
[Experiment 2]

Microwave irradiation test A quartz U-shaped tube having an inner diameter of 10 mm was placed in the center of the applicator portion of the waveguide type microwave irradiation apparatus. The U-shaped tube was filled with activated carbon having a thin coating thickness of Comparative Example 1 to a height of about 2 cm. An optical fiber type thermometer sensor was placed in the center of the activated carbon, and a microwave of 2.45 GHz and 200 W was irradiated while monitoring the temperature. The results are shown in FIG.
At this time, the state of the spark discharge is shown in FIG. 3 in which a signal from the photosensor is taken into an oscilloscope (Tektronix TDS220). That is, the peak on the vertical axis in FIG. 3 indicates the occurrence of spark discharge.
In the same manner, the experiment was also performed on the coated activated carbon of Example 1. The results are shown in FIG. 2 and FIG. The coated activated carbon was stable in temperature even by microwave irradiation, and no spark discharge was observed.
As a result of conducting the same experiment on the coated activated carbon obtained in other examples, almost the same result as the experiment of Example 1 was obtained.
[Experimental Example 3]

Solvent adsorption / desorption test The above-mentioned U-shaped tube was filled with the coated activated carbon of Example 1 to a height of about 2 cm. Nitrogen gas containing 1000 ppm of trichlorethylene was passed through this column at 25 ° C. for about 1 hour to adsorb the trichlorethylene on the activated carbon. After completion of the adsorption of trichlorethylene, irradiation with microwaves (2.45 GHz, 200 W) was performed for 6 minutes while circulating air through the U-shaped tube. As a result, the temperature of the activated carbon rapidly rose and reached 140 ° C. in about 1 minute and became constant. The change in the trichlorethylene concentration of the column outlet gas at that time is shown in FIG. From the weight of the activated carbon before and after the microwave irradiation, it was found that 85% of the adsorbed trichlorethylene was desorbed due to the temperature increase of the microwave irradiation. In addition, by cooling the air containing the desorbed trichlorethylene with a condenser, the trichlorethylene could be easily liquefied and recovered.
[Experimental Example 4]

The coated activated carbon of Example 8 was packed in a 10 cm inner diameter column to a height of 10 cm. Air having an acetone concentration of 10% by weight was passed through the column at room temperature for 1 hour. A similar experiment was performed on activated carbon with a thick coating layer in Comparative Example 3. The increase in weight of activated carbon after 1 hour was measured, and the amount of acetone adsorbed was measured.
The activated carbon of Example 8 adsorbed 18% acetone per weight of the coated activated carbon, but the coated activated carbon of Comparative Example 2 adsorbed only 2% acetone.
[Experimental Example 5]

Catalytic Reaction Experiment Activated carbon coated with the same composition as in Example 8 on activated carbon carrying 1% by weight of platinum in the same apparatus used for the microwave irradiation experiment was obtained. This was filled in a U-shaped tube similar to that described above, and irradiated with microwaves (2.45 GHz, 200 W) for 5 minutes while circulating air. As a result, the temperature of the activated carbon rapidly rose and reached 140 ° C. in about 1 minute and became constant. The catalytic reaction can be carried out by flowing the reaction gas in this state.

  The method of the present invention aims at the temperature of the activated carbon itself easily and uniformly within a short time without generating spark discharge and burning the activated carbon even when irradiated with microwaves or the like in an oxygen-containing atmosphere. It is possible to recover the solvent at small-scale establishments that handle solvents such as dry cleaning shops and paint shops, and it can also be applied to regeneration of activated carbon for gas purification and heating reaction using activated carbon catalyst. .

It is a graph which shows the temperature change of the covering activated carbon by high frequency heating. It is a graph which shows the temperature change of the covering activated carbon by microwave irradiation. It is a graph which shows the measurement of the spark discharge of the covering activated carbon by microwave irradiation. It is a graph which shows the adsorption / desorption curve of a trichrene.

Explanation of symbols

a: Activated carbon with too thin coating b: Activated carbon with activated magnetic material c: Activated carbon with alumina coated d: Activated carbon with too thin coating A: Activated carbon with alumina coated B: Activated carbon with too thin coating

Claims (9)

A method for heating activated carbon, in which activated carbon coated with a heat-resistant and electrically insulating coating material with a thickness of 0.0005 mm to 1.0 mm is irradiated with microwaves or applied with a high frequency. The method for heating activated carbon according to claim 1, wherein the coating material is a heat-resistant coating material that is physically and chemically stable at 200 ° C or lower. The method for heating activated carbon according to claim 1 or 2, wherein the coating material is an electrically insulating coating material having an electrical specific resistance of 1 Ωm or more. The method for heating activated carbon according to claim 1, wherein the ash content in the activated carbon is 15 wt% or less. The shape of the activated carbon covered with the coating material is granular, the average particle diameter is 0.1 mm or more and 20 mm or less, and the coating material is powder, and the average particle diameter is 0.1 μm or more and 100 μm or less. The method for heating activated carbon according to claim 1. The method for heating activated carbon according to any one of claims 1 to 3, wherein the coating material is an inorganic oxide, clay mineral, or ferrite compound. The method for heating activated carbon according to claim 1, wherein the coating material particles are fixed to the surface using water glass. Activated carbon coated with a heat-resistant and electrically insulating coating material with a thickness of 0.0005 mm or more and 1.0 mm or less is packed in a packed tower, adsorbed with solvent or gas, and then irradiated with microwaves or applied with high frequency. A solvent recovery method for desorbing a solvent or gas adsorbed by heating. After charging the reactor with activated carbon which may be coated with a heat-resistant and electrically insulating coating material at a thickness of 0.0005 mm or more and 1.0 mm or less and may carry a catalyst component, microwave irradiation or high frequency irradiation is performed. A catalytic reaction method in which the reaction is promoted by applying and heating.

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