JP2007331986A - Activated carbon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide activated carbon having high adsorption performance in comparison with conventional activated carbon; and to provide applications of the same. <P>SOLUTION: The activated carbon is characterized in that the average macro-pore diameter (δ) is 0.1-1.0 μm, the average macro-pore diameter (δ) and the standard deviation (σ) of the macro-pore diameter distribution satisfy following relation: 0.4≤(δ-σ)/δ<1.0, and the macro-pore volume is 0.05-1.0 mL/g. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to activated carbon having high adsorption performance suitable for a wide range of gas phase and liquid phase processing.

  Due to its excellent adsorption performance, activated carbon is used for air purification such as deodorization and removal of harmful substances, solvent (organic vapor) recovery, water purifier, water treatment such as water purification, sewage, human waste, and industrial wastewater, desulfurization, denitration, canister, catalyst It is used in a wide range of applications such as carrier, decolorization, decolorization in the chemical industry, and gas separation purification.

  For example, Patent Documents 1 to 4 report that activated carbon characterized by the volume of macropores (macropores) has high adsorption performance and is used for various applications.

  In Patent Document 1, activated carbon having a macropore content of 20% or less obtained by chemically activating and densifying a lignocellulosic material that is a carbon-based material is used for a gasoline vapor emission control canister in an automobile. It describes what you can do.

  Patent Document 2 describes activated carbon for water treatment having a pore volume of 0.1 to 0.3 mL / g macropores, which is produced by using coal as a main raw material and adding starch or the like to this. .

Patent Document 3 describes an activated carbon for hydrogen purification, which is an activated carbon material having a specific surface area of 350 to 700 m ² / g manufactured from coconut shell charcoal, and has a macropore volume of 0.10 to 0.20 ml / g. ing.

In Patent Document 4, for water treatment, coal is used as a raw material, and the pore volume of 30 nm or more in diameter is 0.2 to 0.6 ml / g, and the proportion of pore volume of 1 μm or less in diameter is 60% or more. Suitable spherical activated carbon is described.
JP-A-6-9209 JP 2005-319350 A JP-A-6-63397 JP 2006-83052 A

  An object of this invention is to provide the activated carbon which has higher adsorption performance compared with the conventional activated carbon, and its use.

  As a result of intensive studies to find activated carbon having higher adsorption performance as compared with the conventional activated carbon as described in the background art, the present inventor seems to be described in the above Patent Documents 1 to 4 and the like. In addition to controlling the macropore volume, the activated carbon that has high adsorption performance and can be used for a wide range of applications can be obtained by controlling the macropore diameter and the macropore diameter distribution within a predetermined range. I found. Furthermore, as a result of further research based on these findings, the present invention has been completed.

  That is, this invention relates to the following activated carbon and its use.

  Item 1. Activated carbon having an average macropore diameter (δ) of 0.1 to 1.0 μm.

Item 2. Furthermore, average macropore diameter (δ) and standard deviation of macropore diameter distribution (σ)
Item 2. The activated carbon according to Item 1, wherein the relationship is 0.4 ≦ (δ−σ) / δ <1.0.

Item 3. Item 3. The activated carbon according to Item 1 or 2, wherein the macropore volume is 0.05 to 1.0 ml / g.

Item 4. Further, loss on drying (JIS K-1474) is 0.1 to 3.0%.
And the packing density (JIS K-1474) is 0.25 to 0.25.
0.85 g / ml, ignition residue (JIS K-1474)
The activated carbon according to Item 1, 2, or 3, wherein the content is 0.1 to 8.0% and the hardness (JIS K-1474) is 95.0% or more.

  Item 5. Item 5. Activated carbon for solvent recovery comprising activated carbon according to any one of Items 1 to 4.

Item 6. Item 5. An activated carbon for a gasoline canister comprising the activated carbon according to any one of Items 1 to 4.

Item 7. Item 5. Activated carbon for gas separation purification comprising the activated carbon according to any one of Items 1 to 4.

  Hereinafter, the present invention will be described in detail.

  The activated carbon of the present invention has an average macropore diameter of 0.1 to 1.0 μm, preferably 0.2 to 0.9 μm, and more preferably 0.4 to 0.8 μm. By controlling the average macropore diameter of the activated carbon within this range, the activated carbon has high adsorption performance for organic substances, gases and the like.

  The macropore volume of this activated carbon is usually about 0.05 to 1.0 ml / g, preferably about 0.1 to 0.5 ml / g.

  The average macropore diameter and macropore volume are values measured using a mercury intrusion method.

  In this activated carbon, the relationship between the average macropore diameter (δ) and the standard deviation (σ) of the macropore diameter distribution is 0.4 ≦ (δ−σ) / δ <1.0, preferably 0.5 ≦ ( δ−σ) /δ≦0.98. Since the distribution range of the macropore diameter is narrow, there is an advantage that the adsorption equilibrium is quickly reached.

  The standard deviation of the macropore diameter distribution can be calculated by a known statistical analysis method from the measurement data when the above average macropore diameter is measured by the mercury intrusion method.

  The loss on drying (JIS K-1474) is usually about 0.1 to 3.0%, preferably about 0.1 to 1.0%. The packing density (JIS K-1474) is usually about 0.25 to 0.85 g / ml, preferably about 0.3 to 0.8 g / ml. The ignition residue (JIS K-1474) is usually about 0.1 to 8.0%, preferably about 0.1 to 5.0%. The hardness (JIS K-1474) is usually about 95% or more, preferably about 98.0 to 99.9%. Further, the particle size (JIS K-1474) is not particularly specified, but the one in the range of 0.5 to 5.0 mm is 98% or more, preferably the one in the range of 1.0 to 3.0 mm is 98% or more. .

Although not specified BET specific surface area and pore volume in particular, has been recognized as a normal activated carbon, the specific surface area of 500~2500m ² / g approximately, preferably of the order of 800~2000m ² / g, a pore volume of 0 This is about 0.01 to 1.5 ml / g, preferably about 0.1 to 0.8 ml / g.

  The activated carbon of the present invention may take any form such as powdered activated carbon, granular activated carbon (crushed, spherical, columnar formed charcoal, etc.), fibrous activated carbon, activated carbon formed into a honeycomb, etc. From the viewpoint of adsorption performance and handling, granular activated carbon, particularly columnar or spherical shaped coal is preferred.

  The raw material of the activated carbon is not particularly limited. For example, wood powder, sawdust, charcoal, fruit shell (coconut shell, walnut shell, etc.), coal (peat, grass charcoal, lignite, lignite, bituminous coal, anthracite, etc.), coke, coal, Hardened petroleum pitch, natural fiber (eg, hemp, cotton, etc.), synthetic fiber (eg, rayon, polyester, etc.), synthetic resin (eg, polyacrylonitrile, phenol resin, melamine resin, urea resin, polyvinylidene chloride, polycarbonate) , Polyvinyl alcohol) and the like.

  About the manufacturing method of the activated carbon of this invention, the manufacturing method of the granular activated carbon (granulated activated carbon) which is the typical example is demonstrated. Of course, the production method of the present invention is not limited to the following method.

  The manufacturing process of granular activated carbon pulverizes the above-mentioned raw materials to 0.05 mm or less (preferably 0.04 mm or less, more preferably 0.03 mm or less) at 100% by weight, and a binder, and if necessary, Effective catalysts for activation reactions (for example, lithium compounds, potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, potassium hydroxide, sodium hydroxide, and other alkali metals, calcium hydroxide, calcium carbonate, etc.) Alkaline earth metals such as copper compounds, various metal compounds including copper compounds and zinc compounds, various rare earth metal compounds including yttrium compounds, inorganic acids including phosphoric acid and sulfuric acid, melamine , Urea, triethylenediamine, organic compounds such as tetraethylenetriamine), water and interface Sexual agents, heavy oil or creosote oil, high boiling liquid organic compound such as castor oil or lubricating oil, liquid components such as organic solvents, including benzene, toluene, xylene, blended and lubricants such as stearates.

  Examples of the binder include low molecular weight polymers such as coal tar, pitch, starch, molasses, corn starch, solid or liquid phenol resin, melamine resin, and urea resin. The blending ratio of the binder, the liquid component, the lubricant and the like is generally about 25 to 60 parts by weight with respect to 100 parts by weight of the activated carbon raw material.

  The blended mixture is kneaded uniformly while warming. The kneaded material is extruded and formed into a granule by a granulator such as a pelletizer or an injection press. For example, the particle size is about 0.5 to 10.0 mmφ, preferably about 1.0 to 4.0 mmφ, and the length is about 0.5 to 5.0 times, preferably about 1.0 to 3.0 times the diameter. It is formed into a cylindrical shape. If necessary, the particles may be stored under a dry nitrogen or air stream so that the particles do not adhere to each other and harden.

  Then, it heats to about 200 degrees C or less in an airflow, and it dries so that the shape of a molding may not collapse and the surface may not stick. Next, the dried product is heated to about 450 ° C. in an inert gas stream such as combustion gas or nitrogen to harden the surface and then carbonized, or the dried product is gradually in the range of 500 to 900 ° C., preferably 600 ° C. to Carbonized by heating to a temperature in the range of 800 ° C. to produce a dense and hard carbide containing 20% or less of volatile matter. It should be noted that since rapid heating causes cracking and deformation of the particles and affects the activation reaction to some extent, it is preferable to gradually heat and carbonize.

  The activation method of carbide is not particularly limited. Gas activation (steam, carbon dioxide, carbon monoxide, oxygen, hydrogen chloride, ammonia, combustion gas, etc.), chemical activation (zinc chloride, sulfuric acid, phosphoric acid, calcium chloride, sulfide) Any of calcium and the like may be used. Generally preferred is steam activation. For example, the carbide may be activated at a temperature of 750 to 1200 ° C., preferably 800 ° C. to 1100 ° C. After activation, the inorganic substance (ash content) in the carbon is washed and deashed with dilute hydrochloric acid or an alkaline aqueous solution as needed, and further purified by repeated washing with water, followed by drying and sieving. Depending on the use, the activated carbon after the activation may be reactivated at a high temperature or reduced at a high temperature to modify the activated carbon surface. Furthermore, potassium carbonate, caustic soda, potassium iodide, sulfuric acid, phosphoric acid, bromine, morpholine, pyridine, aniline, hydrazine, sulfanilic acids, platinum, vanadium, copper, zinc, chromium compounds, etc. may be used alone or as required. An impregnated activated carbon having an improved adsorption capacity for a specific compound may be prepared by impregnation with a combination of species.

  Since the activated carbon of the present invention has high adsorption performance as described above, it is used for a wide range of applications such as solvent recovery, gas purification such as nitrogen and hydrogen separation and concentration, and a gasoline vapor release control canister.

  For example, typical examples of the present invention include activated carbon for solvent recovery, activated carbon for gasoline canister, activated carbon for gas separation purification, and the like.

The activated carbon for solvent recovery has an average macropore diameter of 0.1 to 1.0 μm, and the relationship between the average macropore diameter (δ) and the standard deviation (σ) of the macropore diameter distribution is 0. 4 ≦ (δ−σ) / δ <1.0, preferably 0.5 ≦ (δ−σ) /δ≦0.98. The macropore volume is about 0.05 to 1.0 ml / g, preferably about 0.1 to 0.5 ml / g, and the loss on drying is usually about 0.1 to 3.0%, preferably about 0.1. It is about 1 to 1.0%. The packing density is usually about 0.25 to 0.85 g / ml, preferably about 0.3 to 0.8 g / ml, and particularly preferably about 0.3 to 0.5 g / ml. The ignition residue is usually about 0.1 to 8.0%, preferably about 0.1 to 5.0%. The hardness is usually about 95% or more, preferably about 98.0 to 99.9%. Moreover, a BET specific surface area of 900-1400 m < ² > / g and a pore volume of 0.3-0.7 ml / g are preferable.

The activated carbon for a gasoline canister is characterized in that the average macropore diameter is 0.1 to 1.0 μm, and the relationship between the average macropore diameter (δ) and the standard deviation (σ) of the macropore diameter distribution is 0. 4 ≦ (δ−σ) / δ <1.0, preferably 0.5 ≦ (δ−σ) /δ≦0.98. The macropore volume is about 0.05 to 1.0 ml / g, preferably about 0.1 to 0.5 ml / g, and the loss on drying is usually about 0.1 to 3.0%, preferably about 0.1. It is about 1 to 1.0%. The packing density is usually about 0.25 to 0.85 g / ml, preferably about 0.3 to 0.8 g / ml, and particularly preferably about 0.3 to 0.5 g / ml. The ignition residue is usually about 0.1 to 8.0%, preferably about 0.1 to 5.0%. The hardness is usually about 95% or more, preferably about 98.0 to 99.9%. Moreover, a BET specific surface area of 1000-1500 m < ² > / g and a pore volume of 0.5-0.8 ml / g are preferable.

  As the activated carbon for gas separation and purification, the average macropore diameter is 0.1 to 1.0 μm, and the relationship between the average macropore diameter (δ) and the standard deviation (σ) of the macropore diameter distribution is 0.4 ≦ (δ−σ) / δ <1.0, preferably 0.5 ≦ (δ−σ) /δ≦0.98. The macropore volume is about 0.05 to 1.0 ml / g, preferably about 0.1 to 0.5 ml / g, and the loss on drying is usually about 0.1 to 3.0%, preferably about 0.1. It is about 1 to 1.0%. The packing density is usually about 0.25 to 0.85 g / ml, preferably about 0.3 to 0.8 g / ml, and particularly preferably about 0.5 to 0.8 g / ml. The ignition residue is usually about 0.1 to 8.0%, preferably about 0.1 to 5.0%. The hardness is usually about 95% or more, preferably about 98.0 to 99.9%. Further, a nitrogen / oxygen adsorption rate ratio of 30 or more, more preferably 32 or more is preferable.

  The activated carbon of the present invention has higher adsorption performance than conventional activated carbon. Therefore, it is suitably used in a wide range of applications such as solvent recovery, gas purification such as nitrogen and hydrogen separation and concentration, and gasoline vapor emission control canister.

  Hereinafter, the present invention will be specifically described with reference to examples and test examples, but the present invention is not limited thereto.

  The drying loss, packing density, ignition residue, particle size (2.00 mm-1.40 mm), and acetone adsorption performance were measured according to JIS K-1474.

  The average macropore diameter and the macropore volume were measured using a mercury intrusion type pore distribution measuring device (AUTOPORE series automatic porosimeter manufactured by Micromeritics).

Production Examples 1-10
100 parts by weight of coal having a particle size of 0.04 mm or less by 100% by weight is circulated in a rotating bed at a temperature of 250 ° C., processed to an oxygen content of 10% by weight, and added with water to hard pitch. The mixture was kneaded with 25 parts by weight and 15 parts by weight of coal tar. At this time, the outer surface of the mixer was heated to 80 ° C. so that uniform kneading could be performed. This kneaded product was filled in an extrusion molding machine to prepare a pellet-shaped molded product having a diameter of 2.0 mm. Next, the pellet-like molded product was heated for about 5 hours until the final temperature reached 800 ° C. while excluding air in a rotary kiln.

  The substances obtained as described above were subjected to evaluation tests in small amounts, and the following groups showing the respective physical properties were collected to obtain respective carbides. These carbides were used as activated carbon raw materials used in Test Examples 1 to 3 described later.

Test example 1
Each of the carbides obtained in Production Example 1 was placed in a rotary kiln, steam was added to the flow gas, and the mixture was treated at 950 ° C. for 120 minutes, then switched to a pure nitrogen gas stream, cooled to room temperature, and the activated product was taken out. Thereafter, the mixture was boiled and washed with a 7% aqueous hydrochloric acid solution 10 times the weight of the carbonized product for 2 hours, and then the operation of boiling washing and draining with 10 times the amount of deionized water was repeated 4 times and dried. This washed activated carbon was again heated in a rotary kiln under a nitrogen gas stream at 900 ° C. for about 2 hours to remove residual hydrogen chloride, and cooled to room temperature to obtain activated carbon for solvent recovery.

  These activated carbons are packed into a two-column solvent recovery test device, and 500 ppm of the test solvent (acetone, benzene, toluene, and methylene chloride) is allowed to flow at 25 ° C for 1 hour, and then 100 ° C steam is reversed for 1 hour. The solvent was removed by washing and regeneration. From the ratio of the recovered solvent amount to the solvent adsorption amount, the solvent recovery rate was determined and performance evaluation was performed.

  Table 2 shows the physical properties and performance evaluation results of this activated carbon.

From Table 2, it can be seen that the activated carbon 1-2 to 1-5 has an average macropore diameter in the range of 0.1 to 1 μm, and the recovery rates of the solvents (acetone, benzene, toluene and methylene chloride) are all high. . On the other hand, it can be seen that in the case of activated carbon 1-1 and 1-6 to 1-10 in which the average macropore diameter is out of the range of 0.1 to 1 μm, the solvent recovery rate is greatly reduced.
Test example 2
Put the carbonized product obtained in Production Example 1 into a rotary kiln, add water vapor to the flow gas, treat at 950 ° C for 150 minutes, switch to a pure nitrogen gas stream, cool to room temperature and take out the activated product It was. Then, boiled and washed with 7% aqueous hydrochloric acid 10 times the weight of the carbonized product for 2 hours, then boiled and washed with 10 times the amount of deionized water for 2 hours and dried four times, dried and activated carbon for gasoline canisters Got.

  These activated carbons were filled in a canister performance test apparatus, and 25 ° C. butane gas was allowed to flow at a flow rate of 1 L / min for 10 minutes, and the weight increase at that time was defined as the butane adsorption amount. Thereafter, nitrogen at the same temperature was allowed to flow at a flow rate of 2 L / min for 10 minutes, and the residual amount of butane was determined from the difference between the weight loss at that time and the butane adsorption amount. The performance of the activated carbon for canisters was evaluated by obtaining the butane recovery rate from the butane adsorption amount and the butane residual amount.

  Table 3 shows the physical properties and performance evaluation results of this activated carbon.

  From Table 3, it can be seen that the activated carbon 2-2 to 2-5 have an average macropore diameter in the range of 0.1 to 1 μm, and the butane recovery rate is high. On the other hand, it can be seen that activated carbons 2-1 and 2-6 to 2-10 whose average macropore diameter is out of the range of 0.1 to 1 μm greatly reduce the butane recovery rate.

Test example 3
The carbonized product obtained in Production Example 1 was put in a rotary kiln, steam was added to the flow gas, and after treatment at 950 ° C. for 30 minutes, benzene / furfuryl alcohol = 50/50% by weight with a nitrogen stream at 800 ° C. The mixture was allowed to flow for 20 minutes at a rate of 100 g / Nm ³ . Finally, after switching to a pure nitrogen gas stream, the mixture was cooled to room temperature to obtain activated carbon for gas separation and purification.

The two-column pressure fluctuation type adsorption test apparatus is filled with the obtained activated carbon for gas separation and purification. Air was fed to the bottom of the adsorption tower under the conditions of a flow rate of about 0.31 m ³ / Hr (space velocity SV = 50 / Hr), a pressure of 0.8 MPa, and a temperature of 25 ° C. to fully contact the adsorbent. Thereafter, the product was taken out of the column from the product recovery line (discharge rate: 0.05-0.18 m ³ / Hr, treatment time 3 minutes). As a result, a recovered product gas mainly containing nitrogen was obtained. The performance was evaluated from the oxygen concentration and nitrogen recovery rate of the product gas.

  Table 4 shows the physical properties and performance evaluation results of the activated carbon.

  From Table 4, it can be seen that the activated carbon 5-2 to 5-5 has an average macropore diameter in the range of 0.1 to 1 μm, and the nitrogen recovery rate is high. On the other hand, it can be seen that the activated carbons 3-1 and 3-6 to 3-10 whose average macropore diameters are out of the range of 0.1 to 1 μm greatly reduce the nitrogen recovery rate.

Claims (7)

  Activated carbon having an average macropore diameter (δ) of 0.1 to 1.0 μm.   2. The activated carbon according to claim 1, wherein the relationship between the average macropore diameter (δ) and the standard deviation (σ) of the macropore diameter distribution is 0.4 ≦ (δ−σ) / δ <1.0.   Furthermore, the activated carbon according to claim 1 or 2, wherein the macropore volume is 0.05 to 1.0 ml / g.   Further, the loss on drying (JIS K-1474) is 0.1 to 3.0%, the packing density (JIS K-1474) is 0.25 to 0.85 g / ml, and the ignition residue (JIS K-). 1474) is 0.1 to 8.0%, and the hardness (JIS K-1474) is 95.0% or more.   Activated carbon for solvent recovery which consists of activated carbon in any one of Claims 1-4.   The activated carbon for gasoline canisters which consists of activated carbon in any one of Claims 1-4. An activated carbon for gas separation purification comprising the activated carbon according to claim 1.