TWI651266B - Spherical activated carbon and method of producing the same - Google Patents

Abstract

The spherical activated carbon of the present invention is a spherical activated carbon integrally molded. The average particle diameter of the spherical activated carbon is 1.5 mm or more and 4.0 mm or less, and the pore volume of the spherical activated carbon is 50 nm or more and 10000 nm or less, and the pore volume is 0.01 ml/g or more and 0.24 ml/g or less. The scope.

Description

Spherical activated carbon and method of producing the same

The present invention relates to a spherical activated carbon and a method of producing the spherical activated carbon.

In the chemical industry, activated carbon is used in separation processes, refining, catalysts, or solvent recovery, and is also used in various applications such as drainage treatment, pollution prevention measures, or medical applications related to global environmental pollution problems.

For example, Patent Document 1 discloses a powdery activated carbon and a granular activated carbon having an average particle diameter of about several mm.

Further, activated carbon (Patent Document 1) using a heavy hydrocarbon oil such as petroleum crucible or ethylene bottom oil, and activated carbon using a resin as a raw material (Patent Document 2) are well known.

[First technical literature] [Patent Literature]

[Patent Document 1] Japanese Laid-Open Patent Publication No. 2005-119947

[Patent Document 2] Japanese Laid-Open Patent Publication No. 2000-233916

[Non-patent literature]

[Non-patent Document 1] Mr. Sanada and other two people "New Activated Carbon Foundation and Application", Kodansha, Inc., March 1, 1992

When using activated carbon, it is required to reduce pressure loss and suppress dust.

When the activated carbon is filled into a device such as a column and the fluid containing a fixed concentration target substance is used and used, in order to maximize the effect per unit volume with respect to the target substance, it is necessary to closely fill the activated carbon particles.

However, when the activated carbon particle size is small, or when the amount of dust generated by the activated carbon is large, the voids between the activated carbon particles are blocked. Further, in such cases, the pressure loss becomes large due to clogging of the device filter or the like, which may cause the load of the device to become large. Moreover, when a large-flow fluid is treated with activated carbon, there may be a phenomenon in which small-sized activated carbon or generated dust scatters.

Further, when the activated carbon and the target substance are separated from each other by bringing the activated carbon into contact with a fluid (gas or liquid) containing the target substance, it is necessary to carry out a treatment such as filtration. However, if the activated carbon particles are small or the amount of dust generated is large, separation takes a lot of time and cost.

In particular, the above-mentioned powdered activated carbon has a substantially small particle size, and the pressure loss becomes large when it is used in a device, and the amount of fluid treatment is restricted.

Moreover, when powdered activated carbon is used as such, the powder may scatter when a large flow of fluid is treated.

On the other hand, in the case of granular activated carbon having an average particle diameter of about several mm, the pressure loss at the time of filling can be reduced, and fluid processing at a large flow rate can be realized.

However, conventionally, in the method for producing granular activated carbon, a method in which powdered carbon and a binder are mixed to produce granular particles is generally employed. That is, the granular activated carbon obtained by the conventional production method is not integrally molded. Therefore, the conventional granular activated carbon is weak in strength, and if the granular activated carbon is used in the apparatus, a large amount of dust is generated and it is difficult to separate from the fluid.

Moreover, since the conventional granular activated carbon generally uses coconut shell activated carbon or the like, there are many impurities, and there are problems in that impurities other than dust are dissolved.

In view of the above, it is required to develop an activated carbon which can suppress pressure loss and dust.

In order to solve the above problems, the inventors of the present invention have conducted intensive studies and found that the use of a spherical activated carbon having a particle diameter of about several mm can suppress pressure loss and dust, and the present invention has been completed.

That is, the present invention provides a spherical activated carbon which is an integrally formed spherical activated carbon having an average particle diameter of 1.5 mm or more and 4.0 mm or less, and has a pore diameter of 50 nm. A spherical activated carbon having a pore volume of 0.01 ml/g or more and 0.24 ml/g or less in the range of 10,000 nm or less.

Further, the present invention provides a method for producing a spherical activated carbon having the above characteristics.

According to the present invention, it is possible to provide an activated carbon which can suppress pressure loss and dust.

Hereinafter, an embodiment of the spherical activated carbon according to the present invention will be specifically described.

[spherical activated carbon]

The spherical activated carbon (hereinafter also referred to simply as "spherical activated carbon") according to the present embodiment has an average particle diameter of 1.5 mm or more and 4.0 mm or less, and a pore volume of 0.01 ml in a range of pore diameter of 50 nm or more and 10000 nm or less. /g or more, 0.24 ml/g or less. In addition, the detailed description of the pore diameter and the pore volume will be described later.

In the present specification, spherical activated carbon means spherical activated carbon. The sphericity of the spherical activated carbon is not particularly limited, and the short aspect ratio is preferably 0.7 or more, more preferably 0.8 or more, and particularly preferably 0.9 or more. The short aspect ratio is the ratio of the short diameter to the long diameter. The length can be calculated by a well-known method, such as the average of the maximum length and the minimum length in the spherical activated carbon projection image. Trail and short diameter. The closer the short aspect ratio is to 1, the closer the spherical activated carbon is to the spherical shape. Further, when the short aspect ratio of the spherical activated carbon is 0.7 or more, when spherical activated carbon is used, the abrasion caused by the collision between the spherical activated carbon particles is further lowered, and the generation of dust can be sufficiently suppressed.

The spherical activated carbon according to the present embodiment is a spherical activated carbon integrally molded. "Integrally formed spherical activated carbon" means activated carbon which is formed into primary particles and has a spherical shape. Since the spherical activated carbon according to the present embodiment has a pore diameter and a pore volume to be described later, it is also referred to as a porous and spherical primary particle activated carbon. The spherical activated carbon according to the present embodiment is excellent in mechanical strength with respect to a conventional spherical activated carbon such as an aggregated particle sintered body. For example, the spherical activated carbon according to the present embodiment has a higher crush resistance than the conventional spherical activated carbon, or has a lower water oscillating wear rate.

(The average particle size)

The lower limit of the average particle diameter of the spherical activated carbon according to the present embodiment is 1.5 mm or more, preferably 1.7 mm or more, and more preferably 1.8 mm, and particularly preferably, from the viewpoint of suppressing an increase in pressure loss of the spherical activated carbon packed bed. 2.0mm or more. Further, from the viewpoint of sufficiently achieving the above-described contact property between the spherical activated carbon and the fluid in the packed bed, the upper limit is 4.0 mm or less, preferably 3.5 mm or less, and more preferably 3.0 mm or less. When the average particle diameter is within this range, the interparticle voids of the spherical activated carbon can be sufficiently increased. Therefore, when such a spherical activated carbon is used, the spherical activated carbon is filled in a device such as a column or a separation tower, and when a fluid containing a target substance is brought into contact therewith, the pressure loss can be sufficiently reduced.

In the present embodiment, the average particle diameter of the spherical activated carbon can be evaluated in accordance with JIS K 1474. Namely, a cumulative particle size distribution curve of spherical activated carbon was produced in accordance with the results obtained by the operation of JIS K 1474. Vertical line and cumulative particle size distribution curve from 50% of the horizontal axis The intersection point, draw a horizontal line along the vertical axis, and calculate the sieve hole (mm) indicated by the intersection point. The mesh value was defined as the average particle diameter of the spherical activated carbon.

(fine pore diameter)

In the present specification, the pore diameter refers to the pore diameter of the pores of the spherical activated carbon. In the present embodiment, the pore diameter and the pore volume can be measured by, for example, a known mercury intrusion method. Further, the pore diameter and the pore volume can be adjusted by, for example, the properties of the crosslinked heavy pitch described later.

(pore volume)

In the present specification, the pore volume refers to the volume of the pores in the specific pore size range of the activated carbon.

The spherical activated carbon according to the present embodiment has a pore volume lower limit value of 0.01 ml/g or more in a range of pore diameters of 50 nm or more and 10000 nm or less, from the viewpoint of the production efficiency of the spherical activated carbon in the production method to be described later. It is preferably 0.02 ml/g or more, more preferably 0.03 ml/g or more, and particularly preferably 0.05 ml/g or more. Further, from the viewpoint of preventing the crushing resistance of the spherical activated carbon from decreasing, the upper limit is 0.24 ml/g or less, preferably 0.22 ml/g or less, more preferably 0.20 ml/g or less, and particularly preferably 0.18 ml. /g below.

In addition, the spherical activated carbon according to the present embodiment has a pore volume lower limit value of 0.01 ml/g or more, preferably 0.02, in a range of a pore diameter of 10 nm or more and 10000 nm or less from the viewpoint of suppressing a decrease in the productivity of the spherical activated carbon. Mol/g or more is more preferably 0.03 ml/g or more, and particularly preferably 0.04 ml/g or more. Further, from the viewpoint of preventing the crushing resistance of the spherical activated carbon from decreasing, the upper limit is 0.28 ml/g or less, preferably 0.27 ml/g or less, more preferably 0.26 ml/g or less, and particularly preferably 0.25 ml. /g is most preferably 0.24 ml/g or less.

According to the present embodiment, by making the spherical activated carbon satisfy the above range, the pores required for the infusibility described later can be sufficiently formed, and the insolubilization can be efficiently performed to produce the spherical activated carbon. Further, the increase in the pore volume which is difficult to participate in the adsorption ability of the spherical activated carbon can be suppressed, and therefore, the density of the spherical activated carbon becomes high, and the unit volume performance of the spherical activated carbon is improved.

In the present embodiment, the pore volume can be evaluated by, for example, a well-known mercury intrusion method.

(resistance to crushing force)

The spherical activated carbon according to the present embodiment is a primary particle and has higher mechanical strength than a conventional spherical activated carbon obtained by sintering aggregated particles. The crushing resistance of the spherical activated carbon of the present embodiment is preferably 1.20 kg/piece or more, more preferably 1.25 kg/piece or more, and particularly preferably 1.30 kg/piece. The crushing resistance may be sufficient, for example, according to the use of the spherical activated carbon, and may be, for example, 10.0 kg/piece or less.

The crush resistance can be measured by the following method. In other words, the sample particles (for example, 30 particles) of the spherical activated carbon are randomly sampled, and the hardness at the moment when the sample particles are crushed is measured using a simple particle hardness meter (manufactured by Tsutsui Chemical Instruments Co., Ltd.). Then, the maximum value and the minimum value in the hardness measurement values are removed, and the average value of the remaining measurement values (for example, the measured value of 28 particles) is calculated and regarded as the crush resistance of the spherical activated carbon.

(dust amount)

In the present specification, dust refers to the fine powder contained in the spherical activated carbon. Further, the amount of dust refers to the amount of the dust, and is specifically the amount calculated by measuring the amount of dust described later.

In the present embodiment, from the viewpoint of suppressing an increase in pressure loss in the spherical activated carbon packed bed, and from the viewpoint of sufficiently exhibiting the separation ability of the spherical activated carbon, the spherical shape The amount of dust contained per 1 g of the charcoal is preferably 2000 μg or less, more preferably 1500 μg or less, particularly preferably 1200 μg or less, and most preferably 1000 μg or less. The smaller the amount of dust, the better, and the lower limit value may be 0 μg or more.

The amount of dust of the spherical activated carbon according to the present embodiment can be measured by a specific method described later. The amount of dust can be reduced by, for example, a one-piece manufacturing method.

(water oscillating wear rate)

If the spherical activated carbon is placed in water and oscillated in water, the spherical activated carbon collides with each other, and the spherical activated carbon is removed and peeled off. In the present embodiment, the oscillating wear rate in water is calculated based on the amount of spherical activated carbon peeled off at this time. Specifically, the water oscillating wear rate can be calculated according to the following formula.

Oscillation wear rate in water (%) = (A - B) / A × 100 (%) ... (Formula 1)

A: mass of spherical activated carbon before shaking in water (g)

B: mass of spherical activated carbon after shaking in water (g)

The spherical activated carbon of the spherical activated carbon according to the present embodiment preferably has an oscillating wear rate of 5% or less, and more preferably 4.5% or less. Further, the lower the oscillating wear rate in the water, the greater the strength of the spherical activated carbon, and the amount of dust generated by the collision of the spherical activated carbons with each other is reduced.

(specific surface area)

The specific surface area is obtained by adsorbing gas molecules to the substance to be evaluated, and calculating the ratio of the molecular weight of the adsorbed gas to the adsorption cross-sectional area of the gas molecules. Specifically, the nitrogen adsorption amount was calculated by the BET method, and the adsorption cross-sectional area of the nitrogen molecule was set to 0.162 nm ² to calculate the specific surface area. In addition, the specific surface area is also referred to as a specific surface area (SSA).

The specific surface area of the gas molecules of the specific surface area according to the present embodiment is nitrogen, and the specific surface area when the spherical activated carbon adsorbs nitrogen at the liquid nitrogen temperature. The specific surface area can be adjusted by, for example, the degree of activation described later.

From play of the spherical activated carbon adsorption function viewpoint, the present embodiment of the spherical activated carbon is preferably a specific surface area of 100m ² / g or more, more preferably 300m ² / g or more, particularly preferably 400m ² / g or more. When the specific surface area is 100 m ² /g or more, the adsorption function of the spherical activated carbon can be sufficiently exhibited. From the above viewpoints, the larger the specific surface area, the better, but it may be within a range in which the desired adsorption function of the spherical activated carbon can be sufficiently obtained, and may be, for example, 4,000 m ² /g or less.

The spherical activated carbon according to the present embodiment can be impregnated with other substances. Other examples include well-known substances which can be impregnated into activated carbon, such as an acid, a base, and a metal. Specific examples of the acid include nonvolatile acids such as phosphoric acid and sulfuric acid, and organic acids such as citric acid and malic acid. Further, specific examples of the base include potassium carbonate, sodium carbonate, potassium hydroxide, and sodium hydroxide. Further, specific examples of the metal include transition elements such as platinum, silver, iron, and cobalt, and compounds thereof.

As described above, in the spherical activated carbon according to the embodiment, the amount of dust contained per 1 g of the spherical activated carbon is preferably 2000 μg or less.

Further, the spherical activated carbon according to the present embodiment preferably has an underwater vibration wear ratio of 5% or less.

Further, the spherical activated carbon according to the present embodiment preferably has a short aspect ratio of 0.7 or less.

Further, the spherical activated carbon according to the present embodiment is preferably impregnated with a base or an acid.

According to the spherical activated carbon according to the present embodiment, the pressure loss and the amount of dust can be suppressed. Therefore, such spherical activated carbon can be used for various purposes. Further, the spherical activated carbon according to the present embodiment is also excellent in crack resistance as compared with the conventional activated carbon.

The method for producing a spherical activated carbon according to the present embodiment is not particularly limited as long as spherical activated carbon having the above characteristics can be obtained. Hereinafter, an embodiment of a method for producing spherical activated carbon according to the present embodiment (hereinafter also simply referred to as "the present manufacturing method") will be described.

[Method for Producing Spherical Activated Carbon] (raw material)

This manufacturing method uses heavy hydrocarbon oil as a raw material of spherical activated carbon. The heavy hydrocarbon oil may, for example, be one or more selected from the group consisting of petroleum hydrazine, coal tar, and ethylene bottom oil.

Among them, in the case of an ethylene bottom oil, it can be obtained by vacuum distillation of a light component of a bottom oil which is produced when ethylene is produced.

Further, a furan resin or a phenol resin, a fossil fuel-derived or plant-derived resin may be used as a raw material of the spherical activated carbon.

The manufacturing method includes (1) manufacture of crosslinked heavy asphalt, (2) addition of additive to crosslinked heavy asphalt, (3) molding of crosslinked heavy asphalt, (4) extraction of additives, and (5) no Melting and (6) calcination. The activation has a total of six processes. Hereinafter, each process will be described in order.

(1) Manufacture of crosslinked heavy asphalt

This manufacturing method first produces crosslinked heavy asphalt. The manufacturing process of the crosslinked heavy asphalt is as described later, and it is ensured that the viscosity adjusting additive is composed of an aromatic compound. It is suitable for the immiscibility and further the process required to achieve the spheroidal asphalt porosity in the additive extraction process.

For the crosslinked heavy pitch, for example, a heavy hydrocarbon oil which is liquid at normal temperature may be subjected to a crosslinking treatment and a heat treatment. Thereby, a crosslinked heavy pitch which is solid at normal temperature can be obtained. A specific method for producing a crosslinked heavy pitch is described in, for example, Japanese Patent No. 4349627.

(2) Adding additives to crosslinked heavy asphalt

Then, an additive is added to the obtained crosslinked heavy asphalt to adjust the viscosity of the crosslinked heavy asphalt, so that the viscosity of the crosslinked heavy asphalt is suitable for spheroidization.

For the additive, for example, an additive for viscosity adjustment such as naphthalene to be described later may be mentioned.

After adding an additive to the crosslinked heavy asphalt and heating and mixing, the crosslinked heavy pitch is formed to obtain a spherical asphalt.

In the present production method, the additive added to the crosslinked heavy pitch derived from the heavy hydrocarbon oil is preferably a 2- or 3-ring aromatic compound having a boiling point of 200 ° C or higher, preferably 205 ° C or higher, more preferably 210 ° C or higher or mixture.

Specific examples of such a preferred additive include, for example, one or more selected from the group consisting of naphthalene, methylnaphthalene, phenylnaphthalene, benzylnaphthalene, formazan, phenanthrene, and biphenyl. Among them, the additive is preferably naphthalene.

When the total amount of the additive of the crosslinked heavy pitch and the additive is 100% by mass, the lower limit is preferably 26% by mass or more, and more preferably 27% by mass or more. It is especially preferably 28 mass% or more. When the amount of the additive added is at most the lower limit value, the obtained porous spherical pitch may not be formed into a sufficient pore. Further, the upper limit thereof is preferably 50% by mass or less, more preferably 45% by mass. It is below the mass percentage, and particularly preferably 40 mass% or less. When the amount of the additive added is at least the upper limit value, the amount of the crosslinked heavy pitch in the mixture of the crosslinked heavy pitch and the additive is relatively small, resulting in a decrease in manufacturing efficiency. Further, since the extraction holes of more than necessary are formed in the process described later, the strength of the obtained spherical activated carbon may be insufficient. By setting the amount of the additive in this range, the additive can be efficiently extracted from the spherical pitch in the later-described process, and the obtained porous spherical pitch can form a sufficient pore. In addition, when the pores of the porous pitch are sufficient, the inside of the porous spherical asphalt can be cross-linked by an oxidation reaction in the infusibilization process to be described later, and the spherical shape of the porous spherical pitch can be secured and carbonized. In addition, when the amount of naphthalene added is, for example, 25 mass%, the pores of the porous pitch are insufficient, and melting may occur.

Further, the pores formed by the above additives are contained in a part of the pore volume of the spherical activated carbon in the range of pore diameters of 50 nm or more and 10000 nm or less.

(3) Forming of crosslinked heavy asphalt

Then, the crosslinked heavy pitch to which the additive is added is molded. At this time, it is preferred to uniformly mix the mixture of the crosslinked heavy pitch and the additive in advance. The mixture of crosslinked heavy asphalt and additives is preferably a molten mixture formed by heating.

The molding of the crosslinked heavy pitch may be carried out in the state of a molten mixture, or the molten mixture may be cooled and then pulverized, stirred in hot water, or the like, and molded. Further, in order to facilitate the subsequent additive extraction process, it is preferred to form the crosslinked heavy pitch into a spherical pitch having a particle diameter of 6.0 mm or less.

For example, water containing a suspending agent is used as a dispersion medium, and a homogeneous mixture of the crosslinked heavy pitch and the additive is melted and dispersed under normal pressure or under pressure to obtain a spherical asphalt.

For other methods of obtaining the spheroidal pitch, for example, the method disclosed in Japanese Patent Publication No. Sho 59-10930 can also be referred to. Specifically, the mixture of the crosslinked heavy asphalt and the viscosity adjusting additive may be extruded into a rod shape in a molten state, or may be stretched, then cooled and solidified, and the obtained rod-shaped pitch is pulverized to prepare a length/diameter. The rod-shaped pitch having a ratio of 5 or less is then stirred and mixed in hot water containing a suspending agent at a temperature higher than the softening point of the rod-like pitch to form a spherical shape.

In the present embodiment, the size of the rod-shaped pitch determines the average particle diameter of the spherical activated carbon. Therefore, in order to make the average particle diameter of the spherical activated carbon 1.5 mm or more and 4.0 mm or less, it is preferable that the dimension of the rod-shaped pitch in the longitudinal direction is about 1.5 to 10 mm. Further, when the rod-shaped pitch is extruded, the diameter of the nozzle is preferably about 1.5 mm to 10 mm.

The rod-shaped pitch obtained in the above manner is placed in hot water heated to a softening point or higher than the mixture of the crosslinked heavy pitch and the additive, and the rod-shaped pitch is softened and deformed to become a spherical pitch.

Further, the molten mixture of the crosslinked heavy pitch and the additive is cooled and pulverized, and the temperature of the hot water when the mixture is stirred in hot water (hereinafter, the temperature is referred to as "spheroidized temperature") can be based on crosslinking of heavy asphalt and The viscosity of the molten mixture of the additive is appropriately set.

In the present embodiment, the spheroidization temperature lower limit is preferably 95 ° C or higher, more preferably 97 ° C or higher, and particularly preferably 98 ° C or higher. Further, the upper limit thereof is preferably 120 ° C or lower, more preferably 115 ° C or lower, and particularly preferably 110 ° C or lower. The spheroidization temperature is set to this range, so that the spherical pitch can be efficiently obtained. Further, if the spheroidization temperature is low, the mixture of the crosslinked heavy pitch and the additive does not deform, and the rod-shaped pitch may not be effectively spheroidized. On the other hand, if the spheroidization temperature is too high, a mixture of crosslinked heavy asphalt and additives It may become a straw bag, or the molten mixture may be broken, which may result in a smaller particle size of the finally obtained spherical activated carbon.

Further, when the rod-shaped pitch is spheroidized in hot water, it is preferred to carry out an operation such as stirring. At this time, if the stirring force is small, the spherical asphalt will precipitate, and the spherical asphalt will fuse with each other. On the other hand, if the stirring force is too high, the shearing force may cause the spherical asphalt to be torn. Therefore, it is preferred to properly choose the spherical asphalt to float in hot water. The best mixing mechanism for the flow and the stirring speed. Further, the method of flowing the spherical asphalt is not limited to stirring, and other appropriate methods may be employed.

Further, in the present embodiment, it is more preferable that the mixture of the above-mentioned crosslinked heavy pitch and the above additive is melted, suspended, and dispersed in hot water in the presence of a suspending agent. That is, when the rod-shaped pitch is spheroidized, it is more preferable to add a suspending agent to hot water. The hot water containing the suspending agent has an effect of improving the dispersibility of the spherical asphalt and preventing the spherical asphalt from being fused to each other. Therefore, in the present embodiment, it is preferred that the mixture of the crosslinked heavy pitch and the additive is melted, suspended, and dispersed in hot water to obtain a spherical pitch.

In the present embodiment, the suspending agent may, for example, be polyvinyl alcohol (hereinafter also referred to as "PVA"), xanthan gum, partially saponified polyvinyl acetate, methyl cellulose, carboxymethyl cellulose, polyacrylic acid and the like. Salts, polyethylene glycols and ether derivatives thereof, ester derivative starches, water-soluble polymer compounds such as gelatin, and the like.

At this time, the concentration of the suspending agent can be appropriately set. Further, the higher the concentration of the suspending agent, the lower the sedimentation speed of the spherical asphalt, so that the spherical asphalt can be dispersed with a smaller stirring force, and the shearing force of the spherical asphalt can be suppressed.

In the present embodiment, when PVA is used as the suspending agent, the lower limit of the content of PVA with respect to the above-mentioned hot water is 0.1 mass% or more, preferably 0.15 mass% or more, more preferably 0.23 mass% or more, and particularly preferably 0.3 mass% or more. Further, the upper limit thereof is preferably 20% by mass or less, more preferably 15% by mass or less, and particularly preferably 10% by mass or less.

Hot water lower limit temperature is preferably 95 ℃, more preferably 97 ℃, particularly preferably not less than 98 ℃. Further, the upper limit thereof is preferably 120 ° C or lower, more preferably 115 ° C or lower, and particularly preferably 110 ° C or lower.

Further, in the present embodiment, a suspending agent and a tackifier may be used at the same time, or only a tackifier may be used alone.

When spheroidizing, a rod on the amount of asphalt and water containing a suspending agent ratio, the liquid is preferably relatively high. Thereby, it is possible to reduce the influence of the small particle diameter and deformation caused by the collision of the bar-shaped pitches with each other.

(4) Extraction of additives

Then, the additive contained in the obtained spherical asphalt is removed, and in the subsequent infusibilization process, pores for diffusing the oxidizing gas into the interior of the spherical asphalt are formed.

In the present embodiment, the crosslinked heavy pitch and the additive have immiscibility, and therefore, it is presumed that the inside of the spherical asphalt is an island structure in which heavy asphalt and an additive are crosslinked. Therefore, the present production method preferably removes the additive portion contained in the spherical pitch using a solvent, thereby forming a pore as an oxygen passage for the spherical asphalt in the subsequent infusing process.

The mass ratio of the solvent to the slurry of the spherical pitch is preferably 7 or more, more preferably 9 or more, and particularly preferably 13. If the mass ratio of the solvent to the slurry of the spherical asphalt is less than 7, then no The method sufficiently extracts the additive inside the particle, and in the subsequent infusibilization process, the pore of the spherical asphalt cannot be formed as an oxygen passage.

As the solvent for extracting and removing the additive from the spherical pitch, an aliphatic compound can be cited. Examples of the aliphatic compound include aliphatic hydrocarbons such as butane, pentane, hexane, and heptane, mixtures of aliphatic hydrocarbons such as naphtha and kerosene, and aliphatic alcohols such as methanol, ethanol, propanol, and butanol. Etc., among them, n-hexane is preferably used.

At this time, the mass ratio of the slurry of n-hexane and the spherical pitch is preferably 7 or more, more preferably 9 or more, and particularly preferably 13 or more. If the mass ratio of the slurry of n-hexane to the spherical pitch is less than 7, the additive inside the particles cannot be sufficiently extracted, and the pores which are the oxygen passages cannot be formed on the spherical pitch in the subsequent infusibilization process.

In the present embodiment, it is preferable to sufficiently form a hole for diffusing oxygen in the non-melting state to the inside. Therefore, it is preferred to sufficiently carry out the operation of extracting the additive from the spherical asphalt.

If the solvent is used as such, the shape of the spherical asphalt can be maintained, and only the additive can be effectively removed.

When the additive is removed from the spherical pitch in the present production method, the through hole can be formed by extracting the additive in the spherical pitch, whereby the porous spherical pitch having uniform porosity can be obtained.

In the present embodiment, the softening point of the porous spherical pitch is greatly affected by the softening point of the crosslinked heavy asphalt. Further, when the softening point is too low, the porous spherical pitch may be softened or melted during the heat treatment for achieving non-melting, which is not preferable.

In the present embodiment, the higher the softening point of the porous spherical pitch, the better. In order to increase the softening point of the porous spherical asphalt, it is preferred to carry out the weighting of the crosslinked asphalt. If the softening point If it is too high, an anisotropic component may be formed in the crosslinked asphalt, and it may be difficult to perform spheroidization of the crosslinked heavy pitch, extraction of the additive, and uniform activation treatment described later.

Therefore, in the present embodiment, the softening point of the porous spherical pitch is preferably 150° C. or higher and 350° C. or lower, more preferably 200° C. or higher and 300° C., and particularly preferably 220° C. or higher and 280° C. or lower.

In addition, the toluene insoluble fraction of the porous spherical asphalt has a good correlation with the carbonization yield of the asphalt, and the higher the toluene insoluble fraction, the higher the carbonization yield. Therefore, the toluene-insoluble matter is preferably 40% or more, and more preferably 50% or more.

(5) does not melt

Next, a porous spherical infusible pitch which is infusible by heat is formed from the porous spherical pitch. On the other hand, in the production method, the pores formed by extracting the additive from the spherical asphalt are used to uniformly diffuse the oxidizing gas into the inside of the porous spherical asphalt, and the crosslinking treatment is carried out. Thereby, a porous spherical infusible pitch can be formed. More specifically, for example, the gas flows through the porous spherical pitch in the fluidized layer at a temperature of 100 ° C or more and 350 ° C or less, preferably 120 ° C or more and 320 ° C or less, more preferably 130 ° C or more and 300 ° C or less. It can be heated.

As the oxidizing gas, an oxidizing gas such as O ₂ , O ₃ , SO ₃ , NO ₂ or air may be used, or a mixed gas of these oxidizing gases may be diluted with an inert gas such as nitrogen gas, carbon dioxide gas or water vapor.

Further, regarding the degree of the crosslinking treatment, the oxidation treatment can be calculated by elemental analysis, and then the oxygen content of the porous asphalt element analysis can be judged. In this case, the oxygen content may be 5 mass% or more, and oxidation treatment is preferably performed to ensure that the oxygen content is preferably 8 mass%. The ratio is more than 25 parts by mass, more preferably 10% by mass or more and 23% by mass or less, and particularly preferably 11% by mass or more and 21% by mass or less.

(6) Calcination. activation

Finally, the porous spherical infusible pitch is calcined into carbon to form pores in the carbon. Further, the pores of the spherical activated carbon formed in the non-melting process are used to diffuse oxygen when not melted. After the calcination. After the activation process, the pores that govern the final adsorption capacity are formed into spherical activated carbon. For example, in the non-oxidizing atmosphere, the porous spherical infusible pitch is heat-treated at a temperature of 600 ° C or higher, preferably 650 ° C or higher, and more preferably 700 ° C or higher, whereby a spherical carbon molded body can be obtained.

Then, the spherical carbon molded body is calcined and activated by a conventional method. At this time, the spherical carbon molded body is subjected to an activation treatment in an active gas atmosphere containing a mild oxidizing gas such as carbon dioxide or water vapor as a main component. Thereby, the spherical activated carbon concerning this embodiment can be obtained.

In the present embodiment, the spherical carbon molded body preferably has an active gas at 600 ° C or higher, more preferably 650 ° C or higher, and particularly preferably 700 ° C or higher. Thereby, carbonization and activation of the spherical carbon molded body can be simultaneously performed, and this operation is preferable from the viewpoint of the economics of the self-made process.

In the present embodiment, the spherical activated carbon obtained as described above may be further impregnated with other substances such as an acid, an alkali or a metal. A well-known method can be used for infiltrating other substances into the spherical activated carbon. For example, if the spherical activated carbon is impregnated or supported with a metal, the spherical activated carbon can be used as a catalyst or the like.

[Examples]

Next, the present invention will be described in more detail with reference to the examples, but the present invention is not limited to the examples.

〔The average particle size〕

The average particle diameter of the activated carbon was evaluated in accordance with JIS K 1474. Specifically, a cumulative particle size distribution curve is prepared according to JIS K 1474, and a horizontal line is drawn along the vertical axis from the intersection of the vertical line of the 50% point of the horizontal axis and the cumulative particle size distribution curve, and the sieve hole (mm) represented by the intersection point is calculated. The mesh value is set to an average particle diameter.

[Pore size and pore volume]

The pore diameter and the pore volume of the activated carbon were measured by a pore volume mercury porosimeter ("AUTOPORE 9200" manufactured by MICROMERITICS Co., Ltd.) by a mercury intrusion method, and the pore diameter and pore volume of the activated carbon were measured. Specifically, activated carbon was placed in a sample container, and degassing was performed for 30 minutes at a pressure of 2.67 Pa or less. Next, mercury is introduced into the sample container, and the pressure is gradually applied to press the mercury into the pores of the activated carbon. Then, based on the relationship between the pressure at this time and the amount of mercury intrusion, the pore volume distribution of the activated carbon was calculated using the following calculation formulas.

Regarding the calculation of the pore diameter, when mercury is pressed into the cylindrical pores of the diameter (D) by the pressure (P), the surface tension of the mercury is set to "γ", and between the mercury and the pore walls. The contact angle is set to "θ", and since the surface tension and the pressure acting on the cross section of the pore are balanced with each other, -πDγcos θ = π(D/2) ² . The relationship of P...(Formula 2) is established. Therefore, D = (-4 γ cos θ) / P (Expression 3)

In the present specification, the surface tension of mercury is set to 484 dyne/cm, the contact angle between mercury and carbon is set to 130 degrees, the pressure P is set to MPa, and fine is expressed in μm. The pore diameter D is calculated by the following formula: D = 1.24 / P (Formula 4). The relationship between the pressure P and the pore diameter D is calculated.

Further, in the present embodiment, the pore volume having a pore diameter in the range of 50 to 10,000 nm corresponds to the volume of mercury pressed in the corresponding mercury intrusion pressure range.

[Evaluation of the amount of dust]

The amount of dust of the activated carbon was evaluated according to the following procedure.

1) The film filter (ADVANTEC diameter 47 mm, pore diameter 1 μm) was dried in advance at 110 ° C for 1 hour, and then placed in a desiccator to be cooled, and then weighed with a precision balance to the nearest 0.1 mg.

2) Take 5 g of the dried sample into a 100 ml Erlenmeyer flask and weigh it with a precision balance to the nearest 0.1 mg.

3) 100 ml of pure water was added to the Erlenmeyer flask, and the mixture was washed in an ultrasonic cleaning machine (Bransonic Desktop Ultrasonic Cleaner 1510J-MT, manufactured by EMERSON, Japan) for 3 minutes.

4) The ultrasonically cleaned suspension was filtered with a sieve having a pore size of 106 μm, and the filtrate was filtered with a membrane filter attached to a microfilter suction device. The wall of the conical flask of the above 3) process was flowed with pure water and filtered through a membrane filter.

5) Put the sample remaining on the sieve in the above 4) process back into the Erlenmeyer flask, and after adding 100 ml of pure water, repeat the above 3) and the above 4) operation a total of 3 times.

6) After drying the filtered membrane filter at 110 ° C for 1 hour, it was left to cool in a desiccator for 30 minutes, and then weighed with a precision balance to the nearest 0.1 mg.

7) Calculate the amount of toner according to the following formula.

Toner amount = (B-A) / S... (Formula 5)

A: Quality of the membrane filter before filtration (g)

B: mass of the membrane filter after filtration (g)

S: sample quality (g)

[water oscillation wear rate]

The oscillating wear rate in the water of activated carbon was evaluated according to the following method.

1) A membrane filter (pore size: 0.3 μm) which was previously dried at 110 ° C for 1 hour was placed in a desiccator and cooled, and then weighed with a precision balance to the nearest 0.1 mg.

2) Weigh about 10g of dry sample, accurate to 0.1mg, transfer to a 200ml separatory funnel, add 50ml of pure water, and use a oscillating machine (IWKI industrial KM-SHAKER model VS amplitude 40mm, oscillation frequency 250 times reciprocating / minute ) Oscillation for 120 minutes.

3) The suspension was filtered through a sieve having a pore size of 150 μm, and the filtrate was suctioned and filtered using a membrane filter. Pure water was passed through the wall of the separatory funnel of the above 2) process, and it was also filtered with a membrane filter.

4) After drying the membrane filter at 110 ° C for 30 minutes, it was left to cool in a desiccator for 30 minutes, and the weight of the membrane filter was accurately weighed to the nearest 0.1 mg.

5) Calculate the oscillating wear rate in water according to the following formula.

Oscillation wear rate in water (%) = (b-a) / s × 100 (Equation 6)

a: mass of membrane filter before filtration (g)

b: mass of the membrane filter after filtration (g)

s: sample quality (g)

[specific surface area]

The gas adsorption amount of the sample (carbonaceous material) was measured using a specific surface area measuring device ("FLOWSORB" manufactured by MICROMERITICS) using a specific surface area continuous flow gas adsorption method, and the specific surface area was calculated by the BET formula.

Specifically, the sample was filled in a sample tube, and a sample containing 30 vol% of nitrogen was passed through the sample tube, and the following operation was performed to calculate the amount of nitrogen adsorbed by the sample. That is, the sample tube was cooled to -196 ° C to adsorb nitrogen to the sample. Next, the sample tube was returned to room temperature. At this time, the amount of nitrogen desorbed from the porous spherical carbonaceous material sample was measured by a thermal conductivity type detector, and this was taken as the amount of adsorbed gas (v). Then, using the approximate formula derived from the BET formula: V _m =1/(v.(1-x)) (Expression 7) is calculated at the liquid nitrogen temperature, using a point measurement method of nitrogen adsorption (relative pressure x) = 0.3), Vm was calculated, and the specific surface area of the sample was calculated according to the following formula: specific surface area = 4.35 × V _m (m ² /g) (Equation 8). Further, in each of the above calculation formulas, v is the actually measured adsorption amount (cm ³ /g), and x is the relative pressure.

[filling density]

The packing density was measured in accordance with JIS K1474-1991.

[short aspect ratio]

The short length to diameter ratio of the sample was calculated using a digital microscope ("VHX-700F" manufactured by KEYENCE Corporation).

Specifically, 30 sample particles were dispersed in a petri dish by an average extraction method, and the major axis and minor axis length of each particle were measured by a digital microscope. Then, according to the ratio of the long axis to the short axis length, the short aspect ratio is calculated, and the maximum is 1. In the following examples and the like, the average value of the short aspect ratios of the 30 particles was set to the short aspect ratio.

[compression resistance]

The crush resistance can be calculated by the following method. In other words, 30 pieces of the sample particles of the spherical activated carbon were randomly sampled, and the hardness at the moment when the sample particles were crushed was measured using a simple particle hardness meter (manufactured by Tsutsui Chemical Instruments Co., Ltd.). The maximum value and the minimum value were excluded from the hardness measurement values, and the average value of the measured values of the particle hardness of 28 sample pieces was calculated, and the crush resistance of the sample particles was determined.

[Example 1]

The specific gravity (ratio of the mass of the sample at 15 ° C to the mass of the equal volume of pure water at 4 ° C) in a stainless steel pressure vessel having an internal volume of 25 liters is 1.08, and the bottom oil (ethylene bottom) generated when ethylene is produced. Oil) 10.0kg. Air was blown from the lower side of the reaction vessel at a rate of 3.7 L/min, and the temperature was raised from 230 ° C to 250 ° C under a pressurized condition of 0.4 MPa, and a blowing reaction was carried out for 4 hours and 20 minutes. Thereby 9.5 kg of blowing tar was obtained. The obtained crude tar of 3.0 kg of the obtained tar was subjected to thermal heavy treatment at 385 ° C, and then the light component was distilled off under reduced pressure to obtain 1.4 kg of a blown pitch. The obtained pitch had a softening point of 203 ° C and a toluene-insoluble fraction of 58%.

0.72 kg of the above-mentioned air-blown pitch and 0.28 kg of naphthalene were put into a pressure-resistant container with a stirring blade and an internal volume of 1.5 L, melt-mixed at 200 ° C, and then cooled to 140 to 160 ° C and extruded to obtain a rod having a diameter of 2 mm. Shaped body. Next, the rod-shaped molded body was pulverized to a length of about 2.0 mm to 2.8 mm. Into 1 L of an aqueous solution in which 1.2% by weight of polyvinyl alcohol (saponification ratio = 88%) as a suspending agent was dissolved and heated to 100 ° C, about 450 ml of the above-mentioned pulverized product was charged. The pulverized material is spheroidized by stirring and dispersion, and then cooled, and the aqueous polyvinyl alcohol solution is replaced with water to obtain a spherical asphalt molded body slurry. After removing most of the water by filtration, the naphthalene in the spherical asphalt slurry was extracted and removed by using 7 times by weight of the spherical asphalt slurry in n-hexane to obtain a porous spherical pitch. Using a fluidized bed, the porous spherical asphalt obtained in the above manner was passed through heated air while being heated from room temperature to 150 ° C for 1 hour, and then The temperature increase rate of 20 ° C / h was raised from 150 ° C to 260 ° C, and then maintained at 260 ° C for 1 hour for oxidation. Thereby, a porous spherical infusible pitch which is infusible by heat is obtained. Then, using a fluidized bed, the porous spherical infusible pitch was activated at 850 ° C in a nitrogen atmosphere containing 50 vol% of water vapor to a packing density of 0.79 g/ml to obtain a spherical activated carbon. The average particle diameter, pore diameter distribution, dust amount, water oscillating wear rate, specific surface area, and short aspect ratio of the obtained spherical activated carbon were evaluated.

[Examples 2 to 8]

As shown in Tables 1 and 2, in addition to changing the amount of asphalt, the amount of naphthalene, the amount of rod-shaped molded body during spheroidization, the spheroidization temperature, the concentration of polyvinyl alcohol, and the extraction of naphthalene, respectively, when the blowing pitch and naphthalene are melt-mixed, respectively. Other operations were the same as in Example 1 except for the amount of n-hexane and the packing density after activation, and the activated carbons of Examples 2 to 8 were obtained.

[Example 9]

As shown in Table 1, in addition to adjusting the amount of asphalt, the amount of naphthalene, the size of the rod-shaped molded body, the amount of the rod-shaped molded body when spheroidized, the spheroidizing temperature, the polyvinyl alcohol concentration, and the like, Other than the amount of n-hexane in the case of extracting naphthalene, other operations were carried out in the same manner as in Example 1 to obtain a porous spherical pitch.

The porous spherical pitch obtained by the standing layer was heated with air, and was heated from room temperature to 150 ° C for 1 hour, and then heated from 150 ° C to 260 ° C at a temperature increase rate of 20 ° C / h, and then 260 Oxidation was carried out for 1 hour at °C. Thereby, a porous spherical infusible pitch which is infusible by heat is obtained. Then, the porous spherical infusible pitch was activated at 850 ° C in a nitrogen atmosphere containing 50 vol% of water vapor using a standing layer to a packing density of 0.70 g/ml to obtain activated carbon.

[Example 10]

As shown in Table 1, in addition to adjusting the amount of asphalt, the amount of naphthalene, the size of the rod-shaped molded body, the amount of the rod-shaped molded body when spheroidized, the spheroidizing temperature, the polyvinyl alcohol concentration, and the like, Other than the amount of n-hexane in the case of extracting naphthalene, other operations were carried out in the same manner as in Example 1 to obtain a porous spherical pitch.

The porous spherical pitch obtained by the standing layer is heated with air, and is heated from room temperature to 150 ° C for 1 hour, and then heated from 150 ° C to 300 ° C at a temperature increase rate of 20 ° C / h, and then 300 Oxidation was carried out for 1 hour at °C. Thereby, a porous spherical infusible pitch which is infusible by heat is obtained. Then, the porous spherical infusible pitch was activated at 850 ° C in a nitrogen atmosphere containing 50 vol% of water vapor using a standing layer to a packing density of 0.68 g/ml to obtain activated carbon.

[Comparative Example 1]

The operation was the same as in Example 1 except that the pitch was 0.75 kg and the amount of naphthalene was 0.25 kg, but the activated carbon was produced, but calcined. In the activation process, the porous spherical infusible pitch molded body is melted, and the shape (spherical shape) cannot be maintained.

[Comparative Example 2]

As shown in Table 1, except that the amount of the blown asphalt and the amount of naphthalene, the spheroidization temperature, the polyvinyl alcohol concentration, and the amount of hexane were adjusted, the other operations were the same as in Example 1, and activated carbon was produced, but calcined. In the activation process, the porous spherical insoluble pitch molded body is melted, and the shape (spherical shape) cannot be maintained.

[Comparative Example 3]

As shown in Table 1, activated carbon was produced in the same manner as in Example 1 except that the amount of the blown asphalt and the amount of naphthalene, the spheroidization temperature, and the polyvinyl alcohol concentration were adjusted. As a result, the shape of the asphalt molded body obtained in the molding process of the crosslinked heavy asphalt is all elliptical.

[Comparative Example 4]

The rod-shaped molded body having a diameter of 1.0 mm was pulverized to a length of about 1.0 mm to 1.5 mm, and as shown in Table 1, except for adjusting the amount of the blown asphalt and the amount of naphthalene, the spheroidization temperature, the polyvinyl alcohol concentration, and the amount of hexane. Other operations were the same as in Example 1, and activated carbon was obtained.

[Comparative Example 5]

The same evaluation as in Example 1 was carried out for the spherical egret X7000H (Osaka GAS CHEMICALS Co., Ltd.).

[Comparative Example 6]

The same evaluation as in Example 1 was carried out for KURARAY COAL SW (KURARAY CHEMICALS Co., Ltd.).

The results of the above respective examples and comparative examples are summarized in Tables 1 and 2.

In Table 1, "size" means the size of the rod-shaped molded body, and "input amount" means the amount of input of the rod-shaped molded body. Further, the "suspending agent" is, for example, PVA. Further, "Rhex" means the mass ratio of hexane at the time of extraction, and more specifically, the mass ratio of n-hexane to the spherical pitch slurry (the amount of n-hexane / the amount of the spherical pitch slurry).

In Table 2, "D1" means melting, and "D2" means all of them are elliptical. Further, "Vp1" means a pore volume in the range of 10 to 10,000 nm, and "Vp2" means a pore volume in the range of 50 to 10,000 nm. Also, "Asw" refers to the oscillating wear rate in water, "Rasp" refers to the short aspect ratio, and "Sp" refers to the crush resistance.

[Industrial Availability]

The present invention is suitably used as an activated carbon such as a separation process, purification, catalyst or solvent recovery.

Claims (10)

A spherical activated carbon characterized in that it is a spherical activated carbon having an average particle diameter of 1.5 mm or more and 4.0 mm or less, and a pore volume of a pore diameter of 50 nm or more and 10000 nm or less is 0.01 ml/ The range of g or more and 0.24 ml/g or less, and the crushing resistance is 1.20 kg/piece or more. The spherical activated carbon according to claim 1, wherein the spherical activated carbon has a dust content of less than 2000 μg per 1 g. The spherical activated carbon according to claim 1 or 2, which is oscillated for 120 minutes under the conditions of an amplitude of 40 mm and an oscillation frequency of 250 reciprocation/minute, and the water oscillation wear rate calculated by the following formula is 5% or less. Wear rate (%) = (AB) / A × 100 (%) A: mass of spherical activated carbon before shaking in water (g) B: mass (g) of spherical activated carbon after shaking in water. The spherical activated carbon according to claim 1 or 2, which has a short aspect ratio of 0.7 or more. The spherical activated carbon according to claim 1 or 2, which is impregnated with a base or an acid. A method for producing a spherical activated carbon, which is a method for producing a spherical activated carbon according to any one of claims 1 to 5, which comprises the following process: for the origin of heavy hydrocarbon oil a process for adding a 2 or 3 ring aromatic compound having a boiling point of 200 ° C or more as an additive to a heavy asphalt; a mixture of the above-mentioned crosslinked heavy pitch and the above additive is melted, suspended, and dispersed in hot water, and a process for obtaining a porous spherical asphalt by using a solvent extraction additive for the spherical asphalt slurry thus obtained; The above porous spherical asphalt is not melted and calcined. a process for activation treatment; the above heavy hydrocarbon oil is one or more selected from the group consisting of petroleum hydrazine, coal tar, and ethylene bottom oil, and the hot water temperature is 95° C. or higher and 120° C. or lower. The aliphatic compound has a mass ratio of the above solvent to the spherical pitch slurry of 7 or more. The method for producing a spherical activated carbon according to the sixth aspect of the invention, wherein the total amount of the additive of the crosslinked heavy pitch and the additive is 100% by mass, and the additive is added in an amount of 26% by mass or more. , 50% by mass or less. The method for producing a spherical activated carbon according to claim 6 or 7, wherein the additive is naphthalene. The method for producing a spherical activated carbon according to claim 6 or 7, wherein the mixture of the crosslinked heavy pitch and the additive is melted, suspended, and dispersed in hot water in the presence of a suspending agent. . The method for producing a spherical activated carbon according to claim 9, wherein the suspending agent is one or more compounds selected from the group consisting of polyvinyl alcohol and xanthan gum.