JP2001129567A - Method for treating waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating waste water through a catalytic wet-type oxidation process capable of decomposing waste water containing organic and/or inorganic oxidative substances at a comparatively low temperature and under comparatively low pressure by using a catalyst, and further capable of holding high efficiency for a long period of time. SOLUTION: When waste water containing organic and/or inorganic oxidative substances is treated, the waste water is treated by using a catalyst containing an activated carbon as a catalyst component having a total volume of fine pores of 0.15 to 0.50 cc/g, a pore diameter of 0.1 to 10 μm, and a specific surface area of 10 to 2,000 m2/g. The waste water is treated at 30-200 deg.C and under pressure to maintain the waste water in liquid phase by supplying the gas containing oxygen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for wet-oxidizing waste water containing organic and / or inorganic oxidized substances by using a catalyst and supplying oxygen-containing gas.

[0002]

2. Description of the Related Art As a method of treating wastewater containing an organic or inorganic oxidized substance, a biochemical method called an activated sludge method and a wet oxidation treatment method called a Zimmerman method have been conventionally known. . However, each of these methods has the following problems.

First, in the activated sludge method, it takes a long time to decompose organic substances, and only low-concentration wastewater can be treated. Therefore, it is necessary to dilute wastewater to an optimum concentration. Has the disadvantage that it becomes vast.
The activated sludge method is a biological treatment method using microorganisms. However, since the microorganisms used are greatly affected by temperature and the like, it is difficult to maintain stable operation.

On the other hand, the Zimmerman method is a method in which wastewater is treated at high temperature and high pressure and in the presence of oxygen to decompose organic substances in the wastewater. In this method, as a means for increasing the reaction rate and relaxing the reaction conditions,
For example, a catalytic wet oxidation method using a catalyst in which various oxides, ion exchange resins, activated carbon, precious metal elements and the like are combined has been proposed.

However, if wastewater containing various oxidizable organic substances is treated by this method, for example, a large amount of acetic acid, which is hardly decomposable, is produced as a reaction intermediate in the latter stage of the reaction. Is 160-250 ° C,
High temperature and high pressure conditions are still required, for example, it is necessary to process at 10 to 70 kg / cm ² G or more.

In general, the types of components contained in wastewater to be treated are rarely the same. For example, besides organic compounds containing no nitrogen, sulfur or halogen, nitrogen-containing compounds, organic halogen compounds or In many cases, sulfur-containing compounds and the like are contained in wastewater. However, in the above-described conventional method, the treatment efficiency of wastewater containing nitrogen compounds such as amine compounds, amide compounds, and amino acid compounds is, in fact, not sufficiently satisfactory.

[0007] The treatment of wastewater containing a sulfur-containing compound is performed in different ways depending on the form of the sulfur compound. For example, in the case of wastewater containing an organic sulfur compound, a biological treatment method is generally used, but a compound which is considered to have a bad effect on living organisms in sludge such as thiofin is contained. In such a case, the biological treatment method cannot be applied, and it is necessary to employ a combustion treatment method.
However, even in this combustion treatment method, it is necessary to add an auxiliary fuel, and when a large amount of sulfur is contained, a large amount of a sulfur compound is generated. There is a problem of bulkiness.

The above-mentioned organic halogen compounds have been used in various applications since the compounds are stable. Further, since this organic halogen compound is nonflammable and has a high degreasing power, it is used in a large amount as a degreasing cleaning agent, a cleaning agent for dry cleaning, and the like in the metal, mechanical, and electronic industries. However, this compound is hardly decomposable, accumulates in the environment, and underground pollution is evident in various parts of the country, causing problems in various places.

Various methods for treating such organic halogen compounds have been proposed or implemented so far, and these methods can be roughly classified into two methods, a nondecomposable method and a decomposable method. . Among these, non-decomposable methods include stripping (operation of removing organic halogen compounds contained in wastewater into a gas phase by contacting with water or heating), aeration, and volatilization by heating, etc. Although the operation itself is very simple and can be carried out at low cost, this method only emits the organic halogen compound in the liquid into the atmosphere, and is not a fundamental solution of environmental pollution by the organic halogen compound. In addition, with regard to the adsorption method, which is one of the non-decomposable methods, a secondary treatment such as a recovery step after the adsorption and a treatment step of the adsorbent is required.

On the other hand, various methods such as an irradiation method, a microbial decomposition method, and an oxidation-reduction method are known as a decomposing method, but they have not been put to practical use as a method for decomposing with high efficiency, and they are harmful. It has also been pointed out that secondary decomposition products are generated.

Among the various methods described above, the catalytic wet oxidation method using a catalyst requires high-temperature and high-pressure conditions, and when the treatment temperature is lowered, for example, acetic acid as an intermediate cannot be decomposed. If the point can be overcome, it can be expected as the most useful processing method.

[0012]

SUMMARY OF THE INVENTION The present invention has been made under such a circumstance, and an object of the present invention is to compare waste water containing organic and / or inorganic oxidized substances by using a catalyst. It is an object of the present invention to provide a method for treating wastewater by a catalytic wet oxidation method, which can be effectively decomposed at a low temperature and a low pressure and can efficiently treat wastewater for a long period of time.

[0013]

According to the present invention, there is provided a method for treating wastewater, which comprises the steps of: treating a wastewater containing an organic and / or inorganic substance to be oxidized; And 0.1 to 10 μm
m having a pore diameter of 0.15 to 0.5.
50 cc / g and specific surface area of 10 to 2,000 m ² /
g, using a catalyst, and treating the wastewater by supplying an oxygen-containing gas to the wastewater in a temperature range of 30 to 200 ° C. and under a pressure at which the wastewater retains a liquid phase. is there.

In the method of the present invention, the catalyst may further comprise Pt, Pd, Rh, Ru, Ir, A as another component.
It is preferable that the catalyst B contains at least one element selected from the group consisting of g and Au as the catalyst B component. When the catalyst B component is contained, the catalyst B
The content of the component is 0.05 to 5 in the form of a metal or an oxide.
Mass% (based on the entire catalyst) and 70% or more of the content of the catalyst B
Preferably, it exists at a position up to 0 μm.

On the other hand, apart from or together with the catalyst B component, Mn, Co, N
It is preferable that at least one element selected from the group consisting of i, Ce, Fe, Ti, Zr, Mg, Te and Bi be contained as a catalyst C component. Is preferably 0.05 to 20% by mass (based on the whole catalyst) in terms of oxide.

According to the present invention, the oxidizable substance contained in the target wastewater is at least one selected from the group consisting of nitrogen-containing compounds, sulfur-containing compounds, organic halogen compounds such as dioxins, and fatty acids. In particular, these substances can be effectively oxidatively decomposed and removed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have studied from various angles a catalyst that efficiently decomposes oxidizable substances in wastewater under relatively low temperature and low pressure conditions. As a result, using a catalyst having a specific form containing at least activated carbon as a catalyst component, the oxygen-containing gas at 30 to 200 ° C. and at a relatively low temperature and low pressure of about the pressure required for the wastewater to maintain a liquid phase. The present inventors have found that the oxidized substances in the wastewater can be efficiently decomposed by operating with the supply.

The catalyst used in the present invention comprises at least activated carbon as a catalyst component (hereinafter sometimes referred to as "catalyst A component").
And the total volume of the pores having a pore diameter of 0.1 to 10 μm is 0.15 to 0.50 cc / g.
The specific surface area is as described above, and the specific surface area is 10 to 2,000 m ² / g.

First, if the pore diameter of the catalyst is 0.1 μm or more, the diffusion of the substance to be oxidized and oxygen becomes easy, so that the reaction proceeds very easily, and efficient decomposition at low temperature and low pressure is possible. Becomes On the other hand, the pore diameter is 0.1 μm
With a catalyst having a large number of pores, the oxidized substance is less likely to be adsorbed to the catalytically active sites, and not only does decomposition not proceed efficiently, but also oxygen is not used efficiently for the decomposition of the oxidized substance, and excess oxygen is used. It is used for the combustion of activated carbon, making long-term use of the catalyst difficult. From these viewpoints, 0.
The total volume of pores having a pore diameter of 1 μm or more is 0.1
It is necessary to use a catalyst of 5 cc / g or more.

On the other hand, the upper limit of the pore size of the catalyst is set to 10 μm because oxygen is easily diffused when the pore size is large, but when the pore size is too large, supply of oxygen to the catalytic active site does not proceed efficiently. There is a need. The volume of the pores having the pore diameters as described above is preferably 0.20 cc / g or more. However, if the pore volume is too large, the strength of the catalyst is reduced. Therefore, the upper limit is 0.50 cc / g. Is good.

The physical properties of the catalyst as described above largely depend on the activated carbon as a catalyst component. To prepare a catalyst using such activated carbon, for example, a raw material such as charcoal, coconut husk charcoal, coal, coke or the like is finely pulverized. Then, it can be molded by mixing a binder therewith. Alternatively, an activated carbon having the above-mentioned physical properties may be selected from activated carbons having various physical properties obtained by ordinary methods using the above-mentioned raw materials. Further, an activated carbon having physical properties defined in the present invention can be obtained by adding an oxidizing agent such as nitric acid or hydrogen peroxide or by baking.

By the way, activated carbon often contains ash derived from raw material components, and it is considered that even if such activated carbon is applied to the present invention as it is, it will elute and disappear during the reaction. However, it is also effective to carry out washing with an acidic solution such as nitric acid or hydrochloric acid or hot water as a pretreatment on the activated carbon to remove the ash as described above in advance. . Further, the shape of the catalyst used in the present invention is not particularly limited, and various shapes such as a sphere, a pellet, a column, and a powder can be used.

As described above, in the prior art, activated carbon was sometimes used as one raw material of the catalyst. However, the activated carbon in the prior art was used as a carrier for the catalyst or simply used as an adsorbent for regeneration. This is different from the present invention used as a component of the catalyst whose form is specified.

In the method of the present invention, the temperature of the target waste water is set to 3
The reaction is carried out at a temperature of 0 to 200 ° C. If the temperature is lower than 30 ° C, the treatment efficiency of the organic or inorganic COD component is reduced, and the purification of the wastewater becomes incomplete.
If it exceeds, the amount of combustion of the catalyst increases, and it becomes impractical. A preferable range of this temperature is about 60 to less than 160 ° C. The reaction pressure may be any pressure as long as the wastewater retains a liquid phase.
It is about kg / cm ² G. That is, in the method of the present invention, the reaction proceeds even under relatively low temperature and low pressure conditions as described above.

In carrying out the present invention, it is necessary to supply a predetermined amount of oxygen in order to decompose organic and / or inorganic oxidized substances contained in wastewater. Normal,
Oxidized substances in wastewater are converted into water, carbon dioxide,
The amount of oxygen required to decompose into nitrogen and oxides is called the theoretical oxygen amount. For example, when acetic acid is oxidatively decomposed, CH ₃ CO
Although the reaction of OH + 2O ₂ → 2CO ₂ + 2H ₂ O occurs, the theoretical amount of oxygen required to oxidize 10 g / liter of acetic acid is 10 / (molecular weight of acetic acid) × 32 × 2 = 10.7 g /
Liters.

The amount of oxygen supplied when carrying out the method of the present invention is:
About 0.5 to 5 times the above theoretical oxygen amount is appropriate. That is, when the amount of oxygen is less than 0.5 times the theoretical oxygen amount, the oxidative decomposition of the substance to be oxidized does not proceed effectively. Problems arise in durability. When the oxygen supply amount is in the range of 0.5 to 1.0 times the theoretical oxygen amount, the oxygen amount that completely decomposes the oxidized substance in the wastewater into water, carbon dioxide, oxides, and other ash is insufficient. It is in a state that
For example, oxygen supplied at a ratio of 1.0 times is not used 100% in the end and often remains in exhaust gas after treatment. For this reason, even if the amount of oxygen supplied in such a case is reduced to less than 1.0 times in accordance with the actual processing efficiency, if the excess oxygen state in which oxygen remains after the processing is maintained, There is no hindrance. Further, combustion of the catalyst can be prevented, and the durability can be improved. From such a viewpoint, the amount of oxygen supplied in the present invention is specified to be 0.5 times or more of the theoretical amount of oxygen.

In the present invention, wastewater is treated while supplying a gas containing the above-mentioned amount of oxygen. The type of the oxygen-containing gas used at this time is not particularly limited. Although gas may be used, it is preferable to use inexpensive air, and in some cases, these may be diluted with an inert gas before use. In addition to these gases, oxygen-containing exhaust gas generated from another plant or the like can be used as appropriate.

In the method of the present invention, even if a catalyst consisting only of activated carbon is used, depending on the type and concentration of the substance to be oxidized, the substance exhibits the oxidizing activity necessary to decompose the substance. As a catalyst, Pt, Pd, R as components other than the activated carbon (catalyst A component) as described above
It is also effective to use a catalyst containing at least one element selected from the group consisting of h, Ru, Ir, Ag, and Au (catalyst B component), whereby the catalyst has a further enhanced oxidation activity. be able to.

As the starting material for the catalyst B component, any of oxides, hydroxides, inorganic acid salts, organic acid salts and the like can be used. For example, it is appropriately selected from ammonium salts, oxalates, nitrates or halides. be able to. As a method for preparing the catalyst containing the catalyst B component as described above, any method such as an impregnation-supporting method and an ion-exchange method can be adopted, but a preferable method is a salt of at least one component of the above-mentioned element. A method of immersing a carrier in an aqueous solution to impregnate the carrier with the noble metal salt, and then reducing the noble metal salt is used.

When the above-mentioned catalyst B component is also contained, its content is in the form of a metal or an oxide in an amount of 0.0
It is preferably 5 to 5% by mass. That is, when the content of the catalyst B component is less than 0.05% by mass in the form of a metal or an oxide, the effect of only containing the catalyst B component is not exhibited,
If the amount exceeds 5% by mass, the effect is saturated, and the effect according to the supported amount is not exhibited, and only the catalyst cost is increased.

In order to exhibit the above-mentioned effect of the catalyst B component, it is preferable that 70% or more of the content is present in the surface layer from the outermost surface of the catalyst to a depth of 1,000 μm. . In a more preferred embodiment, 90% or more of the content of the catalyst B component is 600 μm deep from the outermost surface of the catalyst.
It is to be present in the surface layer position up to. As a preparation method for obtaining such a form, any method may be used as long as the catalyst B component is supported on the surface layer. As such a method, for example, a predetermined amount of an inorganic acid salt of the catalyst B component is added to an amount of water corresponding to the water absorption of activated carbon, and the catalyst surface is uniformly dried under an inert gas atmosphere to form a uniform surface layer. And a method of supporting the catalyst B component. Further, the above-mentioned catalyst outermost surface is a surface of a catalyst having a predetermined shape such as a spherical shape, a pellet shape, a columnar shape, a powdery shape, and the depth is a length (distance) from the catalyst surface toward the center. .

On the other hand, apart from or together with the catalyst B component, Mn, Co,
Ni, Ce, Fe, Ti, Zr, Mg, Te and Bi
It is also effective to contain at least one element selected from the group consisting of the catalyst C component, and by including such a catalyst C component, the durability of the catalyst can be improved. That is, in a catalyst containing at least activated carbon,
In some cases, the activated carbon is oxidized in an oxidizing atmosphere and the activated carbon is consumed at an early stage. However, by including the catalyst C component as described above, the oxidized consumption of the activated carbon can be prevented.

As the starting material for the catalyst C component, any of oxides, hydroxides, inorganic acid salts, organic acid salts and the like can be used as in the case of the catalyst B component, for example, ammonium salts, oxalates, nitrates, and the like. Alternatively, it can be appropriately selected from halides and the like. In addition, as a method for adjusting the catalyst containing the catalyst C component as described above, the above-described method can be adopted, but the order in which the catalysts A to C components are supported is not particularly limited.

In order to exert the effect of the component of the catalyst C, the content thereof must be 0.0% relative to the whole catalyst in terms of oxide.
It is preferable that the content be 5% by mass or more, but if the content is excessive, the content of other catalyst components (the catalyst A component and the catalyst B component) relatively decreases, and the catalyst activity tends to decrease rather. Therefore, the content should be 20% by mass or less. still,
The form (kind) of the oxide of the catalyst C component in terms of oxide is MnO ₂ , Co ₂ O ₃ , NiO, CeO ₂ , Fe _{2
O 3, TiO 2, ZrO 2} , MgO, which assumes a TeO _2, Bi ₂ O ₃ and the like.

The wastewater to be treated in the present invention is not particularly limited as long as the wastewater contains various organic and / or inorganic oxidizable substances as oxidizable substances. Examples of the wastewater include organic substances containing no nitrogen and nitrogen-containing substances. When treating wastewater containing compounds, sulfur-containing compounds, organic halogen compounds such as dioxins, wastewater containing fatty acids such as acetic acid, or wastewater that has produced acetic acid etc. as a reaction intermediate product of wet oxidation treatment Particularly useful.

Specific examples of the nitrogen-containing compound, sulfur-containing compound, organic halogen compound or fatty acid as described above include the following. First, the nitrogen-containing compound is an inorganic or organic compound containing at least one or more nitrogen atoms, such as ammonia, hydrazine, dimethylformamide, pyridine, picoline, acetamide, aniline, glycine, alanine, phenylalanine, glutamic acid, lysine, Aspartic acid, serine,
Nitrogen atom-containing organic substances such as methionine, histidine, ethylenediamine, ethanolamine and triethanolamine; cationic or amphoteric surfactants such as dodecylamine; and nitrogen atom-containing polymers such as polyacrylamide. No.

However, the nitrogen-containing compound targeted in the present invention is not limited to the above examples. The nitrogen-containing compound does not necessarily need to be dissolved in water, and may be in a suspended state or a mixture of a plurality of types. The concentration of the nitrogen-containing compound in the wastewater is not particularly limited, but is usually in the range of 10 to 100,000 mg / liter.

The sulfur-containing compound is an inorganic or organic compound containing at least one sulfur atom other than a sulfate group, such as dimethyl sulfoxide, dimethyl sulfone,
Sulfur atom-containing low molecular weight organic substances such as methanesulfonic acid, thiofin, thiophene, p-toluenesulfonic acid, sulfobenzoic acid, thioacetic acid, and naphthalenesulfonic acid, or anionic or amphoteric interfaces such as dodecylbenzenesulfonic acid Examples thereof include an activator, a sulfur-containing polymer such as a polysulfonic acid, and a sulfur atom-containing inorganic substance such as thiosulfuric acid, sulfurous acid, and sodium sulfide. These compounds may be in a state of being dissolved or suspended in an aqueous medium.

The organic halogen compound is an organic compound containing at least a halogen atom.
For example, methyl chloride, methyl bromide, ethyl chloride, ethyl bromide, dichloroethylene, tetrachloroethylene, 1,
Examples thereof include halogen atom-containing compounds such as 1,1-trichloroethane, vinyl chloride, benzyl bromide, p-chlorophenol, trichlorofluoromethane, dichlorofluoromethane, polychlorinated biphenyl, and dioxin.

The fatty acids include formic acid, acetic acid, propionic acid, acrylic acid and the like. As mentioned above, the fatty acid-containing wastewater of the present invention is limited to those containing the above compounds. The present invention is not limited thereto, and a lower fatty acid may be generated as a reaction intermediate product of the wet oxidation treatment.

Hereinafter, the operation and effect of the present invention will be described more specifically with reference to examples. However, the following examples do not limit the method of the present invention. All of them are included in the technical scope of the present invention.

[0042]

EXAMPLES Various catalysts a to k shown below were prepared or prepared.

The catalyst a has a specific surface area of 1050 m ² / g and a specific surface area of 0.1 to 10
The total volume of pores having a pore diameter of μm is 0.25 cc
/ G of activated carbon having a diameter of 4 mm and a length of 3 to 6 mm.

Catalyst b 3.6 g of dinitrodiammineplatinic nitric acid solution (containing 8.26% by mass as Pt) and water were added to 50 g of activated carbon of catalyst a.
A surfactant was added to support platinum inside the catalyst.
Then, dry under nitrogen atmosphere (100 ° C, 10 hours)
Then, it was reduced (300 ° C., 2 hours) under a hydrogen atmosphere. The platinum content of the catalyst thus obtained was 0.6% by mass, the specific surface area was 990 m ² / g, and the total volume of pores having pore diameters of 0.1 to 10 μm was 0.23 cc / g. there were. When the distribution of platinum inside the catalyst was examined by EPMA (electron probe micro analysis), 50% or more of the platinum content was supported from the outermost surface of the catalyst to a depth of 1,000 μm.

Catalyst c 3.6 ml of dinitrodiammineplatinic nitric acid solution (containing 8.26% by mass as Pt) and water were added to 50 g of activated carbon of catalyst a to impregnate the activated carbon. After that, it is dried (100 ° C., 10 hours) under a nitrogen atmosphere, and reduced (3
(00 ° C., 2 hours). The platinum content of the catalyst thus obtained was 0.6% by mass, and the specific surface area was 1030 m ^2.
/ G, the total volume of pores having pore diameters of 0.1 to 10 μm: 0.25 cc / g. In EPMA,
When the distribution of the amount of platinum carried inside the catalyst was examined, the platinum content of 70% was observed from the outermost surface of the catalyst to a depth of 1,000 μm.
% Or more was carried.

Catalyst d A solution in which cerium nitrate was dissolved was impregnated into the activated carbon (catalyst a). Next, drying under a nitrogen atmosphere (100 ° C., 1
0 hours), and calcined (200 ° C., 2 hours), and then 3.6 ml of a dinitrodiammineplatinic nitric acid solution (containing 8.26% by mass as Pt) and water were added to impregnate the activated carbon. Thereafter, drying was performed in a nitrogen atmosphere (100 ° C., 10 hours), and reduction was performed in a hydrogen atmosphere (300 ° C., 2 hours). The platinum content of the catalyst thus obtained was 0.6% by mass, and the CeO ₂ content was 2% by mass. Also,
Specific surface area: 1000 m ² / g, total volume of pores having pore diameters of 0.1 to 10 μm: 0.23 cc / g, 50% of the platinum content from the catalyst surface to a depth of 1,000 μm Existed.

Catalyst e A solution in which iron nitrate was dissolved was impregnated into 50 g of the activated carbon (catalyst a). Next, drying under a nitrogen atmosphere (100 ° C., 1
0 hours), and calcined (200 ° C., 2 hours), and then 3.6 ml of a dinitrodiammineplatinic nitric acid solution (containing 8.26% by mass as Pt) and water were added to impregnate the activated carbon. Thereafter, drying was performed in a nitrogen atmosphere (100 ° C., 10 hours), and reduction was performed in a hydrogen atmosphere (300 ° C., 2 hours). The platinum content of the catalyst thus obtained was 0.6% by mass, and the Fe ₂ O ₃ content was 1.8% by mass. The specific surface area was 940 m ² / g, and the total volume of pores having pore diameters of 0.1 to 10 μm was 0.23 cc / g.

Catalyst f Zirconia sol was impregnated into 50 g of the above activated carbon (catalyst a). Next, after drying (100 ° C., 10 hours) and baking (200 ° C., 2 hours) under a nitrogen atmosphere, 3.6 ml of dinitrodiammineplatinic nitric acid solution (containing 8.26% by mass as Pt) and water were added. Activated carbon was impregnated. Then, it is dried under a nitrogen atmosphere (100 ° C., 10 hours),
Reduction was performed in a hydrogen atmosphere (300 ° C., 2 hours). The platinum content of the catalyst thus obtained was 0.6% by mass,
The ZrO ₂ content was 1% by mass. Also, the specific surface area:
The total volume of pores having a pore diameter of 960 m ² / g and 0.1 to 10 μm was 0.21 cc / g.

Catalysts g to j Catalysts g to j were prepared according to the preparation method of the above catalysts b and e, in which the following catalyst B component and catalyst C component had the following composition (the remainder was catalyst A component). The content in parentheses is the content (% by mass) of each component. Catalyst g: Pd (0.5) Specific surface area: 1020 m ² / g, total sum of pore volumes: 0.1.
25 cc / g Catalyst h: Ir (1.0) / CeO ₂ (2.0) Specific surface area: 940 m ² / g, sum of pore volume: 0.2
2 cc / g Catalyst i: Ru (1.0) / CeO ₂ (1.5) Specific surface area: 950 m ² / g, total volume of pores: 0.2
3 cc / g Catalyst j: Au (1.0) / CeO ₂ (0.3) Specific surface area: 990 m ² / g, total sum of pore volume: 0.2
The distribution of the catalyst B component inside the catalysts in the catalysts e to j was examined by EPMA. As a result, 70% or more of the content was present from the outermost surface of the catalyst to a depth of 1000 μm. Was.

The catalyst has a specific surface area of 1,560 m ² / g and a specific surface area of 0.1 to ¹⁰ μm.
m has a total pore volume of 0.35 cc /
g of activated carbon 50 with a diameter of 4 mm and a length of 3 to 6 mm
To the g, 3.6 ml of a dinitrodiammineplatinum nitrate solution (containing 8.26% by mass as Pt) and water were added to impregnate the activated carbon. Thereafter, drying under a nitrogen atmosphere (100
C. for 10 hours) and reduced under a hydrogen atmosphere (300 ° C., 2 hours).
Time). The platinum content of the catalyst thus obtained is
It was 0.6% by mass. In addition, specific surface area: 1,550 m
² / g, the total volume of pores having pore diameters of 0.1 to 10 μm: 0.32 cc / g. Also, EPMA
When the amount of platinum carried inside the catalyst was examined, 70% of the platinum content was determined at a depth of 1,000 μm from the catalyst surface.
The above was carried.

Example 1 A stainless steel reaction tube was filled with a catalyst (1,000 cc) shown in Table 1 below, and preheated mixed wastewater and air (oxygen concentration 21
%) Was continuously introduced for 1,000 hours, and the COD (Cr) concentration was measured at the inlet and outlet of the reaction tube, and the respective removal rates were determined. Here, COD (Cr) is a chemical oxygen demand, and represents the amount of oxygen necessary to oxidize the oxidizable substance in the wastewater when potassium dichromate is used as the oxidizing agent. The actual value varies depending on the substance, but is about 95 to 100% of the theoretical oxygen amount. The wastewater subjected to the treatment contains formic acid and acetic acid,
The OD (Cr) concentration was 20,000 mg / liter.

The reaction conditions at this time are as follows:
° C, reaction pressure 4 kg / cm ² , waste water supply 2 liter /
It was time, and an oxygen-containing gas (air) twice as much as the theoretical amount of oxygen required to decompose the oxidized substance was supplied. At this time, the durability of the catalyst was evaluated under the following conditions, and COD was also measured when no catalyst was used (no catalyst).
The removal rate was measured.

(Durability of catalyst)
The durability of the catalyst was evaluated by measuring the reduction rate (%) of the catalyst weight after the reaction for 000 hours.

[0054]

[Table 1]

(Example 2) A stainless steel reaction tube was filled with a catalyst (1,000 cc) shown in Table 2 below, and preheated mixed wastewater and air (oxygen concentration 21
%) Was continuously introduced for 1,000 hours, and the COD (Cr) concentration and the nitrogen amount were measured at the inlet and outlet of the reaction tube.
Each removal rate was determined. The wastewater used for treatment at this time
It contained 4,000 mg / l of dimethylformamide and had a COD (Cr) concentration of 20,000 mg / l.

At this time, the reaction conditions are as follows:
° C, reaction pressure 6 kg / cm ² , waste water supply 2 liter /
It was time, and an oxygen-containing gas (air) twice as much as the theoretical amount of oxygen required to decompose the oxidized substance was supplied.

[0057]

[Table 2]

(Example 3) A stainless steel reaction tube was filled with a catalyst (1,000 cc) shown in Table 3 below, and preheated mixed wastewater and air (oxygen concentration 21
%) Was continuously introduced for 100 hours, the COD (Cr) concentration was measured at the inlet and outlet of the reaction tube, and the removal rate was determined. The wastewater subjected to the treatment at this time was a wastewater containing phenol and had a COD (Cr) concentration of 10,000 mg / liter.

The reaction conditions at this time are as follows:
° C, reaction pressure 5 kg / cm ² , waste water supply 2 liter /
It was time, and an oxygen-containing gas (air) 1.5 times the theoretical amount of oxygen required to decompose the oxidized substance was supplied.

[0060]

[Table 3]

Example 4 A stainless steel reaction tube was filled with a catalyst (1,000 cc) shown in Table 4 below, and preheated mixed wastewater and air (oxygen concentration 21
%) Was continuously introduced for 100 hours, the COD (Cr) concentration and the nitrogen amount were measured at the inlet and outlet of the reaction tube, and the respective removal rates were determined. The wastewater subjected to the treatment at this time contained ethanolamine at 10,000 mg / liter, and had a COD (Cr) concentration of 12,000 mg / liter.

The reaction conditions at this time are as follows:
° C, reaction pressure 6 kg / cm ² , waste water supply 2 liter /
It was time, and an oxygen-containing gas (air) twice as much as the theoretical amount of oxygen required to decompose the oxidized substance was supplied.

[0063]

[Table 4]

Example 5 A stainless steel reaction tube was filled with a catalyst (1,000 cc) shown in Table 5 below, and drainage water and air (oxygen concentration 21%) having the following composition were placed from the bottom of the reaction tube.
Was introduced, the COD (Cr) concentration was measured at the inlet and outlet of the reaction tube, and the removal rate was determined.

[Composition of waste water] Na ₂ S: 0.8%, NaSH: 0.3%, Na ₂ C
O ₃ : 0.3%, TOD: 10,000 mg / liter The reaction conditions at this time were a reaction temperature of 120 ° C. and a reaction pressure of 4
An oxygen-containing gas (air) was supplied at a rate of 2 kg / cm ² and a wastewater supply rate of 2 liters / hour, which was twice the theoretical amount of oxygen required to decompose the oxidized substance.

[0066]

[Table 5]

Example 6 A stainless steel reaction tube was filled with a catalyst (1,000 cc) shown in Table 6 below, and preheated mixed wastewater and air (oxygen concentration 21
%) Was continuously introduced for 100 hours, and the COD (Cr) concentration and the p-chlorophenol concentration were measured at the inlet and outlet of the reaction tube by gas chromatography analysis, and the respective removal rates were determined. The wastewater subjected to the treatment at this time contains 4,000 mg / liter of p-chlorophenol, and COD
The (Cr) concentration was 12,000 mg / liter.

The reaction conditions at this time are as follows:
° C, reaction pressure 5 kg / cm ² , waste water supply 2 liter /
It was time, and an oxygen-containing gas (air) twice as much as the theoretical amount of oxygen required to decompose the oxidized substance was supplied.

[0069]

[Table 6]

Example 7 A stainless steel reaction tube was filled with a catalyst (1,000 cc) shown in the following Table 7, and preheated mixed wastewater and air (oxygen concentration 21
%) Was continuously introduced, and the hydrazine concentration was measured by the P-dimethylaminobenzaldehyde method at the inlet and outlet of the reaction tube, and the hydrazine removal rate was determined. The wastewater subjected to the treatment at this time contained 1,000 mg / liter of hydrazine.

The reaction conditions were as follows: reaction temperature 90 ° C.
The reaction pressure was normal pressure, the amount of wastewater supplied was 3 liters / hour, and an oxygen-containing gas (air) twice the amount of oxygen necessary to decompose the oxidized substance was supplied.

[0072]

[Table 7]

Example 8 A stainless steel reaction tube was filled with a catalyst (1,000 cc) shown in Table 8 below, and preheated mixed wastewater and air (oxygen concentration 21
%) Was continuously introduced, the ammonia ion concentration was measured at the inlet and outlet of the reaction tube, and the removal rate was determined. The wastewater used for the treatment at this time is ammonium sulfate [(N
H ₄ ) ₂ SO ₄ ].

The reaction conditions at this time are as follows:
° C, reaction pressure 6 kg / cm ² , waste water supply 2 liter /
It was time, and an oxygen-containing gas (air) twice as much as the theoretical amount of oxygen required to decompose the oxidized substance was supplied.

[0075]

[Table 8]

(Example 9) According to Example 1, the following Table 9
The wastewater treatment by wet oxidation was performed using the catalyst shown in FIG.
The wastewater used for treatment has a dioxin concentration of 6,100.
ng / liter, TEQ (toxic equivalent: Toxic Equivalen
t) 52 ng / liter waste incinerator smoke drainage was used.

The reaction conditions at this time are as follows:
° C, reaction pressure 6 kg / cm ² , waste water supply 1 liter /
Time and 30 Nl / h of air volume.

[0078]

[Table 9]

[0079]

The present invention is constituted as described above, and is effective at a relatively low temperature and a low pressure by using a catalyst having specific physical properties containing at least activated carbon and optionally containing other metal elements. Can be decomposed
In addition, a wastewater treatment method by a catalytic wet oxidation method capable of efficiently treating wastewater over a long period of time has been realized.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01J 23/89 B01J 23/56 301M (72) Inventor Yusuke Shioda 992, Okihama, Nishioki, Abashiri-ku, Himeji-shi, Hyogo Nippon Shokubai Co., Ltd. (72) Inventor Tohru Ishii 992, Nishioki, Okihama-ku, Abashiri-ku, Himeji-shi, Hyogo F-term (reference) BC05 BC06 BC07 BD02 BD08 CA01 4G069 AA02 AA03 AA08 AA12 BA04A BA05A BA05B BA06A BA08A BA08B BB02A BB02B BB04A BB04B BC24A BC32A BC33A BC33B BC43A BC43B BC62A BC66A BC66B CA73 BC72 BC72 BC70 BC70 BC70 BC70 BC72 BC70

Claims (11)

[Claims] In treating wastewater containing an organic and / or inorganic oxidizable substance, the total volume of pores containing activated carbon as a catalyst component and having a pore diameter of 0.1 to 10 μm. Is 0.15 to 0.50 cc / g
And using a catalyst having a specific surface area of 10 to 2,000 m ² / g, supplying an oxygen-containing gas to the waste water in a temperature range of 30 to 200 ° C. and under a pressure at which the waste water holds a liquid phase. A method for treating wastewater, comprising treating the wastewater. 2. The catalyst according to claim 1, further comprising Pt,
The processing method according to claim 1, wherein the catalyst B comprises at least one element selected from the group consisting of Pd, Rh, Ru, Ir, Ag, and Au as a catalyst B component. 3. The treatment method according to claim 2, wherein the content of the catalyst B component is 0.05 to 5% by mass in the form of a metal or an oxide. 4. The treatment method according to claim 2, wherein a catalyst in which 70% or more of the content of the catalyst B component exists at a position from the outermost surface of the catalyst to a depth of 1,000 μm. 5. The catalyst according to claim 1, wherein the catalyst further comprises Mn,
The catalyst according to any one of claims 1 to 4, wherein the catalyst C contains at least one element selected from the group consisting of Co, Ni, Ce, Fe, Ti, Zr, Mg, Te and Bi. Processing method. 6. The treatment method according to claim 5, wherein the content of the catalyst C component is 0.05 to 20% by mass in terms of oxide. 7. The method according to claim 1, wherein the substance to be oxidized is a nitrogen-containing compound. 8. The treatment method according to claim 1, wherein the substance to be oxidized is a sulfur-containing compound. 9. The method according to claim 1, wherein the substance to be oxidized is an organic halogen compound. 10. The treatment method according to claim 9, wherein the organic halogen compound is a dioxin. 11. The oxidizable substance is a fatty acid.
10. The processing method according to any one of 10 above.