JP3138749B2 - Method for producing carbides having deodorizing ability, ion exchange ability, and catalytic ability using plant materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to cellulose, starch or wood containing them, which has an excellent deodorizing ability against a basic gas in a low concentration range such as ammonia and has an ion exchange ability or a catalytic ability. The present invention relates to a carbonized and heat-treated product of plant material such as wood and agricultural waste, and a method for producing the same.

[0002]

2. Description of the Related Art Heretofore, buildings such as livestock pens and factories where the odor emitted is a problem have been located far from residential areas, but due to the deterioration of the residential environment, they have become adjacent to each other. ing. Furthermore, the tightness of the living space has created various odor problems.

One of them is an odor caused by a basic gas. Among the basic gases, ammonia and trimethylamine are legally regulated substances. Since they emit a strong odor even in a trace amount of the order of several ppb to ppm, many deodorants have been proposed as a countermeasure against the odor against the basic gas. In particular, activated carbon has poor basic gas adsorption performance, and inorganic porous materials have good basic gas adsorption, but have low selectivity and are not very effective as adsorbents. Have been reported.

As a method for enhancing the performance as a deodorant, for example, a method of impregnating activated carbon with sulfuric acid and an organic acid (Japanese Patent Laid-Open No.
-63882), a method of adhering and supporting a metal salt on the surface of activated carbon, fiber and other porous materials (JP-A-64-25)
867, JP-A-64-29264, JP-A-64-582
58, JP-A-63-229056, JP-A-63-229
057).

[0005] All of these conventional deodorizing agents are simply obtained by adhering various components to activated carbon or the like, and it is difficult to uniformly adhere them to the surface. In addition, a substance impregnated with an inorganic acidic substance such as phosphoric acid or sulfuric acid poses a serious problem in terms of indoor cleaning because there is a fear of indoor contamination due to vaporization. Although those using a heavy metal compound or a chelate compound have a great effect of removing odorous substances, their applications and use conditions are greatly limited in terms of cost and the like.

On the other hand, examples of the ion exchanger include inorganic ion exchangers, synthetic resins such as polystyrene, cellulose, and the like.
Dextran and the like include sulfone groups, carboxyl groups and the like introduced therein. Although these products are homogeneous and have excellent performance, they are expensive and have limited use.
Also, in consideration of the disposal method after use, synthetic resins are not preferred, and products made from natural plant materials are desirable.

It is well known that charcoal obtained in a low temperature range of about 400 ° C. contains a large amount of acidic groups such as carboxyl groups and hydroxyl groups on the surface of a carbide. Regarding the contribution of this surface functional group to the adsorption performance, a report example on the ammonia adsorption performance using a carbide in a low temperature range (Hitami et al .: Carbon, No. 160, 247-254 (199)
3)), Examples of reports on heavy metal adsorption performance (Kuwaki, Tamura:
New Use Development Research Collection of Charcoal and Wood Vinegar, 27-44 (1
990)).

A report on a method for producing a carbide that can be used as an adsorbent for gases and heavy metals by subjecting charcoal produced at a temperature of 500 to 800 ° C. to air oxidation at 270 to 350 ° C. (Japanese Patent Laid-Open No. 7-241461) ).

However, the basic carbon gas-adsorbing performance and ion-exchange performance of woody carbides are inferior to those of commercial products, so that they have not been widely used.

Activated carbon is one of the most widely used environmental purification materials using wood as a starting material. However, activated carbon has a low ability to adsorb a basic gas, and thus a method has been proposed in which an acidic group is introduced and used as a basic gas or an ion exchanger. For example, a method of introducing an acidic group to the activated carbon surface using an oxidizing agent such as nitric acid or sulfuric acid,
There is a method in which an acidic group is introduced into the surface of a carbide by performing air oxidation together with heating on activated carbon or carbon fiber.

As a wood-like substance, a carbon fiber obtained from an aromatic sulfonic acid (salt) as a raw material is treated in the presence of oxygen for 30 minutes.
Oxygen content is 7 ~ by heat treatment at 0 ~ 600 ° C.
25%, chelating ability is 0.05-0.25mmol / g
Of the adsorbent (JP-A-7-185336).

In addition, the cured novolak resin is used in air at 130 to
Ion exchange capacity by heat treatment at 500 ° C.
Example of ion exchanger production of 5 meq / g or more
104325).

[0013] The unactivated carbon fiber is removed in the presence of oxygen by 250 to 9
An example of producing an adsorbent for a polar gas such as ammonia by treating at 00 ° C. has also been reported (Japanese Patent Application Laid-Open No. 2-2).
53844).

There is also a method in which sulfuric acid or phosphoric acid is attached to fibrous activated carbon in which the ratio of surface oxygen into which an acidic functional group has been introduced by oxidation treatment is 10% or more (JP-A-9-19).
2484).

In the introduction of an acidic group to the surface of activated carbon, physical adsorption due to porosity, chemical adsorption by an acidic group and a function as an ion exchanger can be expected. Treatment, air oxidation at high temperature and heat treatment in a few steps are required. In addition, it is difficult to obtain a product having a high degree of substitution, because the reaction is caused only by oxidation of the carbide surface.

[0016]

SUMMARY OF THE INVENTION Accordingly, the present inventors
Using natural plant materials such as woody materials as raw materials, a method for producing high-performance environmental purification materials in a simpler process was studied. As a result, when heat-treating cellulose, starch or wood or agricultural waste containing them in a temperature range of 250 to 400 ° C., the oxygen concentration in the heating atmosphere is closely related to the acidic group content of the heat-treated product obtained. In addition, it was found that a large amount of acidic groups were introduced into the product under an appropriate temperature and oxygen concentration atmosphere, and that the ion exchange capacity was greatly increased by immersing it in an alkaline solution. Invented the invention.

The present invention utilizes this thermal decomposition reaction, and uses only unused plant resources such as cellulose, starch or woody waste or agricultural waste containing them as raw materials at a temperature of 250 to 400 ° C. The present invention provides a technique for producing a heat-treated product that can be used as a high-performance adsorbent, a catalyst, or an ion exchanger in a simple process of heat treatment.

[0018]

Means for Solving the Problems Wood materials as starting materials are sawdust and bark, wood residue, wood flour, wood fiber, wood chips, chip dust, sun darks, and the like, which are discharged from a wood processing plant. Examples include vegetable fibers such as bamboo grass, straw, and rice husk, and wood materials containing cellulose such as pulp residue and waste paper. Agricultural wastes containing starch or cellulose can also be used as starting materials. A carbide obtained by heat-treating these wood materials and the like at 350 ° C. or lower in a non-oxidizing atmosphere can also be used. Those having a large shape may be pulverized or defibrated before use. In some applications, only the wood surface can be treated and used.

The heat treatment performed in the present invention is a hot air circulation oven, an electric furnace, a continuous carbonization furnace, a fluidized bed carbonization furnace, etc.
A device capable of controlling the temperature in the range of 400 ° C. and changing the atmosphere can be used.

The starting material is heat-treated at 250 to 400 ° C., preferably 300 ° C., in a gaseous atmosphere containing 1 to 25% oxygen.
Heat treatment at ~ 350 ° C. After the heat treatment, it is left to cool naturally.
By changing the oxygen concentration in the gas phase atmosphere during carbonization
To control the chemical structure change and the amount of acidic group generation of carbides
Can be simultaneously immersed in an aqueous alkaline solution
Imparts the property that spray treatment increases ion exchange capacity
be able to.

The carbide obtained in this manner is composed of about 26 to 40% by weight of oxygen and 0.5 to 2.3 mmol of a strongly acidic group.
1 / g, containing 3-5 mmol / g of weakly acidic groups.

It is considered that the portion of the acidic group in the carbide thus obtained, which is determined as a strongly acidic group, is mainly a carboxyl group. It is considered that the portion quantified as a weakly acidic group is mainly a lactone, a phenolic hydroxyl group, an acid anhydride or the like.

In a basic gas or solution, these acidic groups function as adsorption active sites for both strongly acidic groups and weakly acidic groups. Therefore, when used as a basic gas adsorbent such as ammonia, the obtained carbide is used as it is. be able to.

On the other hand, in an acidic or neutral aqueous solution, only a portion substantially corresponding to a strongly acidic group becomes an adsorption active site. The resulting carbide is treated with an alkali, preferably from 0.01 to
It is immersed in a 1.0N aqueous sodium hydroxide solution, filtered, washed with water and dried. Lactone in carbide by alkali treatment,
The anhydride rings open to form the sodium salt. The obtained carbide can be used as an ion exchanger for supporting or adsorbing metal ions.

Next, the alkali-treated carbide is immersed in a metal salt solution, preferably a 0.01 to 1.0 N aqueous solution of a metal salt, filtered, washed with water and dried. The obtained carbide can be used as a catalyst, a deodorant, or the like as a metal carrier. When used as a catalyst, the performance can be further improved by further performing a heat treatment, an oxidation treatment, or the like according to the application.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The carbide of the present invention may be used alone or in the form of a sheet by mixing it with other particles or fibers in the form of granules or fibers, and these may be used by filling them in a container. is there.

[0027]

EXAMPLES (Example 1) Cellulose was used as a sample. The sample was placed in a magnetic crucible, covered, and carbonized under the following conditions. As for the temperature conditions, the rate of temperature rise was 3 ° C./min. Then, the mixture was kept at 300 ° C. for 2 hours and allowed to cool. The atmosphere during the heat treatment was a mixture of air and nitrogen gas to adjust the oxygen concentration. The ion exchange capacity of each of the obtained carbides before and after the alkali treatment was evaluated by an ordinary method. The adsorption isotherm was determined using a constant volume gas adsorption amount measuring device, and the adsorption characteristics of the obtained carbides to ammonia gas were evaluated. As a result an ion exchange capacity high correlation was observed between the oxygen concentration at the time of carbonization (Figure 1), you can take readings claim 1. Further, the ion exchange capacity was greatly increased by the alkali treatment (FIG. 1). Similarly, the amount of adsorbed ammonia (FIG. 2) increased with an increase in the oxygen concentration during carbonization.

Example 2 As a sample, firwood wood flour was used instead of the cellulose of Example 1 above. The following processing was performed similarly. As a result, the ion exchange capacity was greatly increased by the alkali treatment (FIG. 1), and increased with the increase in the oxygen concentration during carbonization along with the amount of adsorbed ammonia (FIG. 3).

Example 3 Cellulose was used as a sample. The sample was placed in a magnetic crucible, covered, and carbonized under the following conditions. As for the temperature conditions, the rate of temperature rise was 3 ° C./min. After keeping at 250 to 400 ° C. for 2 hours, the mixture was allowed to cool. The oxygen concentration was 21%. The ion exchange capacity and ammonia gas adsorption characteristics were evaluated in the same manner as in Example 1. As a result, heat treatment in a temperature range around 300 ° C. was more effective for both the ion exchange capacity and the ammonia gas adsorption characteristics.

(Example 4) As a sample, Aedes pine wood flour was used in place of the cellulose of Example 3 above. The following processing was performed similarly. As a result, heat treatment in a temperature range around 300 ° C. was more effective for both the ion exchange capacity and the ammonia gas adsorption characteristics.

Example 5 Starch was used as a sample instead of the cellulose of Example 3 above. The following processing was performed similarly. As a result, heat treatment in a temperature range around 300 ° C. was more effective for both the ion exchange capacity and the ammonia gas adsorption characteristics. Further, FIG. 4 shows the ammonia adsorption isotherm of the cellulose, firwood and starch carbide obtained in Examples 3, 4, and 5. For comparison, commercially available activated carbon, activated carbon for ammonia, and charcoal were used. As a result, it was found that the treated product obtained in the present invention had better ammonia adsorption characteristics than each of the adsorbents used for comparison.

Example 6 Todomatsu wood flour was used as a sample. The sample was placed in a magnetic crucible, covered, and carbonized under the following conditions. As for the temperature conditions, the rate of temperature rise was 3 ° C./min.
Then, the mixture was kept at 300 ° C. for 2 hours and allowed to cool. The oxygen concentration was 21%. The obtained carbide was immersed in a 0.5N aqueous lead acetate solution, allowed to stand for 24 hours, filtered, and washed with water.
Measurement of the metal content in the obtained residue showed that the carbide supported about 1.2 mmol / g of lead.

(Example 7) The carbide obtained by the method of Example 6 was immersed in a 0.2 N aqueous sodium hydroxide solution, allowed to stand for 24 hours, filtered and washed with water. After drying.
After immersing in a 5N aqueous lead acetate solution and allowed to stand for 24 hours,
It was filtered off and washed with water. As a result of measuring the metal content in the obtained residue, the alkali-treated carbide was found to be about 3.8 mmol /
g of lead.

Example 8 The above Example 6 was used as a metal salt.
Was replaced with a 0.5N aqueous lead acetate solution, and a 0.5N aqueous copper acetate solution was used. Other processes were performed in the same manner as in Example 6. Measurement of the metal content in the obtained residue showed that the carbide supported about 1.3 mmol / g of copper.

Example 9 The above Example 7 was used as a metal salt.
Was replaced with a 0.5N aqueous lead acetate solution, and a 0.5N aqueous copper acetate solution was used. Other processes were performed in the same manner as in Example 7. As a result of measuring the metal content in the obtained residue, it was shown that the alkali-treated carbide carried about 3.9 mmol / g of copper.

[0036]

According to the present invention, wood materials containing cellulose and starch, agricultural wastes and the like are oxidized at 250 to 350 ° C. under oxidative gas phase conditions.
It is intended to provide a novel method for producing a basic gas adsorbent and an ion exchanger by a very simple processing step of carbonizing in a low temperature range.

According to the present invention, the amount of acidic groups generated can be effectively increased by controlling the carbonization conditions, and the carbon nanotubes can be used as high-performance basic gas adsorbents and ion exchangers. In addition, various uses such as a catalyst and a deodorant can be expected as a metal carrier. It can also be expected to be used as a carrier for enzymes and microorganisms.

Therefore, the present invention is effective for the effective use of wood materials, particularly unused materials such as residual materials from forests and wood processing plants, and agricultural wastes.

[0039]

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the oxygen concentration in a carbonizer and the ion exchange capacity of a fir tree material, a cellulose carbide, and a product obtained by alkali-treating these carbides.

FIG. 2 is an ammonia adsorption isotherm of cellulose carbide.

FIG. 3 is an ammonia adsorption isotherm of a firwood charcoal.

FIG. 4 is a graph comparing the ammonia adsorption isotherms of cellulose carbide, firwood charcoal, starch carbide, commercially available activated carbon, activated carbon for ammonia, and charcoal.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C01B 31/10 C01B 31/10 // B01J 20/20 B01J 20/20 A B09B 3/00 B09B 3/00 303H Examiner Misako Anzai (56) References JP-A-9-241014 (JP, A) Proceedings of the Japan Wood Research Society, Hokkaido Section No. 29 (October 1997), p. 49-51 (58) Fields investigated (Int. Cl. ⁷ , DB Name) C01B 31/02 101 B01D 53/02 B01J 21/18 B01J 32/00 B01J 39/22 C01B 31/10 B01J 20/20 B09B 3/00

Claims (2)

(57) [Claims] 1. Wood material containing cellulose such as cellulose or wood, house waste material, sawdust, radish, pulp residue, waste paper, or wood char which has been heat-treated at 300 ° C. or less in a non-oxidizing atmosphere, and starch and agricultural products Starting material is starch-containing material such as waste, and pulverized so as to impart the property of increasing ion exchange capacity when dipped or sprayed with an aqueous alkali solution .
The raw material is placed in a gaseous atmosphere containing 6 to 25% by volume of oxygen.
And heating at a temperature in the range of 250 to 400 ° C., and controlling the amount of generated acidic groups by changing the oxygen concentration in the gas phase atmosphere during the carbonization. For producing a carbide having deodorizing ability and ion exchange ability. 2. A wood material containing cellulose such as cellulose or wood, waste wood, sawdust, radish, pulp residue, waste paper, or wood char which has been heat-treated at 300 ° C. or lower in a non-oxidizing atmosphere, and starch and agricultural products. The starting material is a material containing starch such as waste, and a temperature of 250 to 400 ° C. in a gaseous atmosphere containing oxygen so as to impart a property of increasing ion exchange capacity when immersed or sprayed with an aqueous alkali solution. Within the range, by heating and carbonizing, and by changing the oxygen concentration in the gas phase atmosphere during carbonization, the carbide produced by controlling the amount of generated acidic groups is dipped or sprayed with an aqueous alkali solution and an aqueous metal salt solution. For producing a carbide having a deodorizing ability, an ion exchange ability and a catalytic ability, characterized by supporting a metal. .