JP3299401B2 - Manufacturing method of carbon-based adsorbent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is based on the use of carbon-based fine powder having a carbon content of 90% or more, which is collected from the flue gas of a heavy oil combustion type boiler generally used in factories and the like, as a main raw material.
The present invention relates to a method for producing an adsorbent used for water treatment of oil-containing wastewater and household wastewater of a general factory containing cleaning oil and the like, and for gas adsorption such as deodorization.

[0002]

2. Description of the Related Art In recent years, measures to prevent environmental pollution have been taken up as a global issue. Pollution and discharge of rivers and seawater due to wastewater discharged from each factory and daily wastewater discharged from households. Air pollution by gas and the like have been taken up as a major social problem, and there is a need for an adsorbent having a suitable adsorptivity that can be used for such environmental purification. Conventionally, as an adsorbent, a zeolite, silica gel, alumina or the like is used as a raw material for an inorganic type, a carbonaceous adsorbent obtained from coconut shell charcoal, coal, and charcoal is used for an organic type, and an ion exchange resin is used for a synthetic type. And chelate resins are known, but it is required to find a new raw material supply source from the viewpoint of effective use of resources.

[0003] In recent years, large heavy oil combustion boilers generally used in factories and the like generally have an electric dust collector installed in the middle of the chimney suction port from the exhaust port of the boiler to supplement carbon fine powder generated during combustion. Gathering. Although this carbon-based fine powder varies depending on the quality of heavy oil used as a fuel, it often contains impurities such as sulfur oxide, nickel, vanadium, copper, chromium, and iron. Therefore, if these carbon-based fine powders are left in an open space, they absorb rainwater and atmospheric moisture, they emit heavy metal ions such as vanadate ions and copper ions, and wastewater containing sulfuric acid. It is clear. Also, in the case of treating as industrial waste, there is also a problem of securing a treatment site and reducing treatment costs, and a proposal for effective use of the carbon-based fine powder has been awaited.

On the other hand, as a carbon-based molded article, Japanese Patent Publication No. Sho 62-3
No. 0210, JP-B-62-30212, JP-B-62-30211 and JP-B-62-30213 disclose a thermosetting granular or powdered phenolic resin whose production method is disclosed in JP-B-62-30213. By using as a binder, a molded article having excellent strength can be obtained, as disclosed in Japanese Patent Publication No. 60-59167 and Japanese Patent Publication No.
No. 2247, etc. However, in these molding methods, a technology has been established that uses carbon-based fine powder having an inexpensive and stable supply source and sufficiently controls properties such as porosity, specific surface area, and pore size distribution required as an adsorbent. It is not at present.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel oil-fired boiler which is mostly treated as industrial waste by using a thermosetting granular or powdered phenolic resin. Carbon content collected from flue gas
Effectively uses carbon-based fine powder of 90% or more and has an adsorption capacity that can be used for industrial or general household wastewater treatment.
Another object of the present invention is to provide an adsorbent which is satisfactory in strength.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have developed a carbon-based fine powder having a carbon content of 90% or more collected from the combustion exhaust gas of a heavy oil-fired boiler which is mostly treated as industrial waste. The present invention has been completed as a result of intensive studies on the effective use of carbonaceous materials, and is characterized by 5 to 40 parts by weight of thermosetting granules or A granular molded product containing 3 to 25 parts by weight of a water-soluble binder,
This is a method for producing an adsorbent, which comprises carrying out carbonization and activation treatment at a temperature of ° C.

The carbon-based fine powder collected by a dust collector attached to a combustion gas exhaust part of a heavy oil combustion boiler used in the present invention can be used after being washed with water, then dehydrated and dried. As described above, since it often contains heavy metals such as nickel, vanadium, copper, chromium, and iron, it may be acid-washed with dilute hydrochloric acid or dilute nitric acid, and then neutralized with an alkali such as aqueous ammonia. After that, it can be used after further washing with water, dehydrating and drying to reduce the content of impurities. The bulk density of the carbon fine powder after drying is usually about 0.20 to 0.40 g / cc. The pore diameter distribution is about 0.05 to 10 μm, particularly 1 to 4
Most are about μm, and the pore volume is about 1-3 cc / g. In most cases, the carbon content of the carbon-based fine powder is usually 90% or more, but the range of 93 to 97% is particularly large.

The thermosetting granular or powdery phenolic resin applicable to the present invention is obtained by JP-B-62-3021 or JP-B-62-30213, and (A)
Containing spherical primary particles having a particle size of 0.1 to 150 μm and secondary aggregates thereof, and (B) at least 50% by weight of the whole
Is large enough to pass through a 100 Tyler mesh sieve, and (C) the methanol solubility defined in the text of the description is
50% by weight or more, and (D) the free phenol content is 500 ppm or less as measured by liquid chromatography. The features are as follows.

At room temperature, while stirring a mixed aqueous solution consisting of 15 to 22% by weight of hydrochloric acid and 7 to 15% by weight of formaldehyde, a mixture of phenol or a mixture of phenol and a nitrogen-containing compound such as urea, melamine, aniline is added. The mixture is added at a ratio of 1/15 or less based on the mixed aqueous solution, and the stirring is stopped and allowed to stand before white turbidity is generated in the reaction system. During standing, white or pink granular or powdery phenolic resin is formed and settles in the reaction system. Next, while stirring the entire reaction system, if necessary, the entire system was heated to a temperature of 50 ° C. or lower to complete the reaction, and then the resulting solid was taken out and washed with water as necessary. For example, 0.1-1% by weight
After neutralization treatment with ammonia water, water washing, dehydration and drying are performed.

Most of the granular or powdery phenol resin is composed of primary particles or secondary aggregates having a particle size of 0.1 to 150 μm, and at least 50% by weight of the whole, preferably at least 50% by weight.
90% by weight is large enough to pass through a 100 Tyler mesh sieve, but is distributed with a peak between 1 and 50 μm. The granular or powdered phenolic resin according to the present invention has a free phenol content of 500 ppm or less as measured by liquid chromatography, substantially 100 ppm.
These are: In addition, as measured by GPC (gel permeation chromatography), it is a polymer having a weight average molecular weight in terms of polystyrene of 1000 or more, but substantially melts or fuses when held at a temperature of 100 ° C. for 5 minutes. There is a thing, it exerts the effect as a binder.

The granular or powdery phenolic resin applied to the present invention, when heated to reflux in 500 ml of substantially anhydrous methanol, has the following formula: S = {(W ₀ −W ₁ ) / W ₀ } × Here, W ₀ : weight of the resin used (g) W ₁ : weight of the resin remaining after heating and refluxing (g) S: solubility of the resin in methanol (% by weight). Methanol solubility represented by 50% by weight or more,
Preferably it is at least 70% by weight, most preferably at least 90% by weight. If the methanol solubility is less than 50% by weight, the heat fusibility decreases, and it is difficult to obtain the effect as a binder. Furthermore,
Since the resin has a reactive methylol group in the molecule,
The resin itself is thermosetting, for example, methanol solubility 95
Since the gelation time at 150 ° C. of the resin by weight at 150 ° C. is as long as 4 to 5 minutes, the curing can proceed according to the heating conditions and purpose.

Among the above thermosetting granular or powdery phenolic resins applicable to the present invention, Japanese Patent Publication No. 62-30211
In the infrared absorption spectrum obtained by the KBr tablet method, the resin obtained in ( ¹ ) has an absorption intensity of ₁₆₀₀ cm ^-1 (absorption peak attributed to benzene) in the range of D ₁₆₀₀ , 990 to 1015 cm ^-1 (absorption peak attributed to a methylol group). the most significant absorption intensity D _900-1015, the absorption intensity of 890 cm ^-1 (absorption peak of hydrogen atoms of isolated benzene nuclei) when expressed in _{D 890, D 900-1015 / D 1600} = 0.2~9.0 D of ₈₉₀ / D ₁₆₀₀ = 0.09 to 1.0, and the resin obtained in JP-B-62-30213 shows an infrared absorption spectrum by KBr tablet method of 1450 to 1500.
The largest absorption intensity in the range of cm ^-1 (the absorption peak attributed to the aromatic double bond) is D _1450-1500 , and 960-1020
When the largest absorption intensity in the range of cm ^-1 (the absorption peak attributed to the methylol group) is represented by D _960-1020 , it has a feature of D _960-1020 / D _1450-1500 = 0.1 to 2.0, Each shows that the compound contains a reactive methylol group in the molecule.

The content of the above-mentioned thermosetting granular or powdery phenolic resin specified in the present invention is as follows.
The amount is 5 to 40 parts by weight, preferably 10 to 35 parts by weight, most preferably 20 to 30 parts by weight based on 00 parts by weight. When the content of the thermosetting granular or powdered phenolic resin is 5 parts by weight or less, the strength of the carbonized activated adsorbent is low, which is not preferable. Conversely, if the content of the phenolic resin is at least 40 parts by weight, the workability during granulation will be reduced, and the strength after carbonization activation will be undesirably reduced.

The water-soluble binder used in the present invention includes, for example, polymer binders such as polyvinyl alcohol and water-swellable cellulose derivatives. As the polyvinyl alcohol, those having a polymerization degree of 500 to 2000 and a saponification degree of 70% or more are preferably used. Further, as the cellulose derivative, for example, methylcellulose, carboxymethylcellulose, hydroxypropylmethylcellulose and the like are preferably used. The water-soluble binder
May be used as it is, or may be used as a 3-20% aqueous solution.

The content of the water-soluble binder specified in the present invention is 3 to 25 parts by weight, preferably 4 to 20 parts by weight, most preferably 5 to 15 parts by weight based on 100 parts by weight of the carbon fine powder. If the content of the water-soluble binder is 3 parts by weight or less, the workability at the time of granulation is reduced, and problems such as difficulty in extruding from a die and unevenness of the shape and easy generation of powder are caused. . If the amount is more than 25 parts by weight, the workability during granulation is lowered and the strength after carbonization activation is also weakened, which is not preferable.

In the present invention, the addition of water other than the water dissolved in the water-soluble binder is not limited at all, and the amount of water added may be adjusted according to the granulation state.

Furthermore, in the present invention, for example, ethylene glycol, polyoxyethylene, alkyl ether, polyoxyethylene fatty acid ester, and ammonium polycarboxylate are used in order to improve the workability during mixing and granulation as long as their properties are not impaired. , A crosslinking agent for polyvinyl alcohol, a plasticizer for extrusion granulation, and the like can be added in small amounts.

The raw material components of the present invention are uniformly mixed by a mixing device such as a ribbon mixer, a V-type mixer, a cone mixer, a kneader and the like, and then formed into granules. Forming into a granular material is, for example, a single-screw or twin-screw wet extrusion granulator, a vertical granulator such as a basket
It can be performed by a semi-dry disk pelletizer or the like.
This molding is usually performed at room temperature, but may be performed under heating depending on the case. The shape of the granular material is preferably, for example, cylindrical or spherical. Although the size of the granules obtained by granulation is not particularly limited, for example, a cylinder having a diameter of 0.5 to
5mm, length about 1-10mm, 0.5 ~ 10m for spherical
m is preferred.

The granular compact obtained as described above is
The desired adsorbent is obtained by carbonization and activation treatment at 1100 ° C.

The carbonization and activation treatment at 600 to 1100 ° C. in the present invention means that carbonization is carried out in a temperature range of 600 to 1100 ° C. in a non-oxidizing atmosphere, and after carbonization, the carbonization is carried out in an oxidizing atmosphere.
Activation in the temperature range of 00 to 1100 ° C, or 600
To perform carbonization and activation simultaneously in an oxidizing atmosphere at ~ 1100 ° C.

The temperature for the carbonization and activation treatment is preferably 7
00-950 ° C, most preferably 750-900 ° C. If the temperature of the carbonization and activation treatment is higher than 1100 ° C., the pores contributing to the adsorption inside the carbonized pellets are thermally shrunk and decreased, so that the adsorption capacity is undesirably reduced. On the other hand, if the temperature is lower than 600 ° C., the carbonization and activation are not sufficient, and the adsorbing ability is low.

The non-oxidizing atmosphere in this case is, for example, an atmosphere of nitrogen, argon, helium or the like, and the oxidizing atmosphere is, for example, oxygen, carbon dioxide, water vapor or a mixture of two or more of these. It is an atmosphere of gas, or nitrogen, argon, helium, or the like containing these gases. The rate of temperature increase until reaching the maximum treatment temperature in the carbonization step is not particularly limited, but is preferably 5 to 50.
0 ° C / H. Further, zinc chloride, phosphoric acid, and the like are added to the granular compact obtained by performing carbonization and activation as described above.
The adsorbent can also be obtained by applying potassium hydroxide, potassium sulfide, or the like, heating the mixture to 600 to 1100 ° C. in a non-oxidizing atmosphere, and activating the adsorbent together with carbonization.

The carbon-based adsorbent obtained by the present invention is usually in the form of pellets, its packing density is 0.35 to 0.70 g / cc, its pore diameter measured by mercury porosimetry is 0.01 to 10 μm, and its pore volume is 0.1 to 10 μm. The pore diameter is about 10 cc / g, the pore diameter measured by the nitrogen adsorption method is 7 to 100 mm, and the pore volume is 0.01 to 0.
It is about 2cc / g. Further, the tensile strength is about 30 to 80 kg / cm ² . The specific surface area of the carbon-based adsorbent is usually 100 to
800 m ² / g, preferably from 300~800m ² / g.

[0024]

The adsorbent obtained by the present invention has the above-mentioned physical characteristics and can be used for wastewater treatment and deodorization treatment from factories and general households. Among them, it is suitable for removing oil content and oily odor of oil-containing wastewater. Hereinafter, specific examples will be described.

[0025]

【Example】

Example 1 20 kg of carbon-based fine powder having a carbon content of 90% or more collected from the combustion exhaust gas of a heavy oil boiler was washed with 100 l of 0.1N nitric acid, filtered, and then neutralized with 0.1N ammonia water. Wash well. Thereafter, 100 parts by weight of the carbon-based fine powder dried at 90 ° C. for 16 hours was mixed with a thermosetting granular or powdered phenolic resin (Bellpar, manufactured by Kanebo Co., Ltd., average particle diameter).
A predetermined amount of 20 μm, a solubility of 95% in methanol, a degree of polymerization of 500, a polyvinyl alcohol having a saponification degree of 99% (hereinafter abbreviated as PVA), and water are weighed in predetermined amounts, and the resulting mixture is kneaded (manufactured by Fuji Paudal Co., Ltd.). , KDHJ-20 type) at room temperature for 15 minutes to obtain 10 kinds of uniform kneaded products having the compositions shown in Table 1. These were dried with a semi-dry granulator (Fuji Paudal Co., Ltd., Disk Peretta F-20 / 12-330, die diameter 3.
(0mmφ), and then dried at 90 ° C for 6 hours.
Thus, a cylindrical granular compact having a length of 5 to 15 mm was obtained.

[0026]

[Table 1]

However, samples 1 and 7 having compositions outside the scope of the present invention could not be granulated, and sample 6 could extrude the kneaded material from the die, but lacked the binder. Therefore, it was difficult to maintain a granular form. Sample 10 had too much binder and had very poor dischargeability from the die. For samples 2 to 6 and 8 to 10 that could be granulated, the temperature was raised to 850 ° C at a heating rate of 50 ° C / H in a nitrogen atmosphere using a cylindrical electric furnace with an inner diameter of 70 mmφ, followed by carbonization. Steam activation (activation gas composition: N ₂ / H ₂ O = 1/1 flow rate: 2 Nl / min) was performed at this temperature for 120 minutes. Table 2 shows the characteristic values of the obtained carbonized product.

[0028]

[Table 2] The pore volume of each sample is obtained by measuring and analyzing the adsorption isotherm of nitrogen gas.
The pore characteristics were evaluated with a pore volume of Å or less. The strength of the granulated product and the carbonized product pellet was measured with a Kiya hardness meter.

The load value evaluated by the strength measurement is a value immediately before the pellet is crushed, and the tensile strength takes into account the pellet diameter and the pellet length and is expressed by the following equation. Tensile strength: σ [kg / cm ² ] = 2P / πdl P: load [kg] d: pellet diameter [cm] l: pellet length [cm]

As can be seen from Tables 1 and 2, the samples produced from the granular compacts in the composition range of the present invention have high strength in both the granulated product and the carbonized product, but have a higher content of bell par. In sample 2 having a small amount, the granulated product has strength due to the binder effect of PVA, but the carbonized product has little strength because PVA is thermally decomposed and most of the binder component is lost. It turned out to be pellets and was not practical. Sample 6 having a Bellpar content not less than the range of the present invention has poor granulation properties, so that the strength of the granulated product pellets is weak, and even if carbonized, the strength is not sufficient.
Sample 7 with a low PVA content cannot be granulated, but PV
The granulation property is improved as the content of A increases. However, when the content exceeds the range of the present invention, the granulation property is reduced, and the strength of both the granulated product and the carbonized product is reduced. Table 2
Thus, the packing density of each sample is almost the same as that of commercially available activated carbon, but the difference is apparent in the specific surface area, and the larger the content of bell par, the larger the value. The pore characteristics reflect the value of the specific surface area, and a sample having a larger bell par content has a larger pore volume having a pore diameter of 20 mm or less, which is the most important for adsorption of oil and oil odor.

Example 2 100 parts by weight of the carbon-based fine powder, which had been washed with an acid, neutralized, washed with water, and dried in the same manner as in Sample 4 of Example 1, were mixed with the phenol-based powder.
After kneading with 25 parts by weight of resin powder, 6 parts by weight of PVA and 56 parts by weight of water with a kneader, molding and drying,
The temperature was raised to 500 ° C, 700 ° C, 850 ° C, 1000 ° C, and 1200 ° C at 50 ° C / H and carbonized.
Steam activated for minutes. Table 3 shows the characteristic values of the obtained carbonized product.

[0032]

[Table 3]

Sample 11 having a carbonization activation temperature of 500 ° C. has a small specific surface area and hardly any pores. The specific surface area increases with increasing temperature, reaching a maximum at 850 ° C. However, Sample 15 having a carbonization activation temperature outside the range of the present invention is too high in temperature, so that both the specific surface area and the pore volume are small.

Example 3 A carbonized product was prepared in the same manner as in the sample 13 of Example 2 using bell pars having different methanol solubilities (ethanol solubilities: 95%, 80%, 60% and 30%). Obtained. Table 4 shows the characteristic values of these carbonized products.

[0035]

[Table 4] As shown in Table 4, the sample having the highest methanol solubility
13 has a maximum value in all of strength, packing density, specific surface area and pore volume, and all values decrease as the methanol solubility decreases.

EXAMPLE 4 100 parts by weight of the carbon-based fine powder which had been washed with an acid, neutralized, washed with water and dried in the same manner as in Sample 4 of Example 1 were mixed with the phenol
After kneading with 25 parts by weight of resin powder, 6 parts by weight of PVA and 56 parts by weight of water with a kneader, molding and drying,
The temperature was raised to 950 ° C at 50 ° C / H to carbonize, and activated at that temperature for 1 hour, 2 hours, 4 hours, 6 hours, and 10 hours under different carbon dioxide atmospheres (flow rate 2Nl / min) . Table 5 shows the characteristic values of the obtained carbonized product.

[0037]

[Table 5]

The sample 19 having an activation time of 1 hour has a small specific surface area, which is not preferable, but the specific surface area increases as the activation time increases. However, samples with an activation time of 6 hours
22 is the maximum value for both the specific surface area and the pore volume, and the activation time
On the other hand, in the sample 23 for 10 hours, those values become smaller.

Example 5 Samples 20 to 22 of Example 4 and a commercial activated carbon as a comparison were evaluated for oil adsorption characteristics. Oil absorption characteristics are as follows. First, add 20 μl of machine oil (Daphne Rotary Compressor Oil A) to 1 liter of water and seal it tightly. Shake (YS-8D manufactured by Yayoi Co., Ltd .: shaking). 30mm width,
After shaking for 20 hours at a shaking speed of 250 times / min), filter and
An oil-containing aqueous solution was prepared so that the oil concentration in the sample water was about 10 ppm. For 200 ml of this oil-containing aqueous solution, samples 20 to 22
And 0.02 g, 0.04 g, 0.08 g, 0.12 g, 0.20 g of commercial activated carbon respectively
g, 0.40 g, sealed, shaken with this shaker for 1 hour, filtered, and measured the oil content on the filtrate and filter paper with a carbon tetrachloride-extracted infrared oil content meter (OCMA-200, manufactured by HORIBA, Ltd.) The total amount was taken as the remaining amount of adsorption, the amount of adsorption of each sample was determined, and the oil adsorption isotherm was determined. Table 6 shows the oil adsorption of each sample at 5 μl / l, which is close to the concentration of oil discharged from general factories and households. It was found that Samples 21 and 22 exhibited a considerably large oil-adsorbing ability, and in particular, Sample 22 had almost the same oil-adsorbing drainage adsorbing performance as commercial activated carbon.

[0040]

[Table 6]

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-64-61306 (JP, A) JP-A-49-30288 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 20/00-20/34

Claims (1)

(57) [Claims] 1. A thermosetting granule or powder of 5 to 40 parts by weight based on 100 parts by weight of carbon-based fine powder having a carbon content of 90% or more collected from the combustion exhaust gas of a heavy oil combustion boiler. A method for producing an adsorbent, comprising subjecting a granular molded product containing a phenolic resin and 3 to 25 parts by weight of a water-soluble binder to carbonization and activation treatment at 600 to 1100 ° C.