JP2002253966A - Catalyst for waste water treatment and manufacturing method thereof and method of treating waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst capable of effectively oxidizing and decomposing an organic and/or inorganic material to be oxidized at the time of treating waste water containing the material by a catalytic wet oxidation method, a manufacturing method of the catalyst and a method of treating the waster water efficiently at a relatively low temperature and low pressure stably through a long period by the catalytic wet oxidation method. SOLUTION: The catalyst for treating the waster water contains activated carbon and further contains the below-mentioned component (a) and/or component (b). The component (a) is at least one element selected from a group composed of Ti, Zr, Hf, Nb, Ta, Fe, Co, Mn, Al, Si, Ga, Ge, Sc, Y, La, Ce, Pr, Mg, Ca, Sr, Ba, In, Sn, Sb and Bi. The component (b) is at least one elements selected from a group composed of Pt, Pd, Rh, Ru, Ir and Au.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a catalyst for wastewater treatment which can effectively oxidize and decompose wastewater containing organic and / or inorganic oxidizable substances when the wastewater is treated by a catalytic wet oxidation method. And methods for producing such catalysts,
The present invention also relates to a method for treating wastewater by a catalytic wet oxidation method capable of treating wastewater stably for a long period of time efficiently at a relatively low temperature and low pressure.

[0002]

2. Description of the Related Art As a method for treating wastewater containing organic or inorganic oxidizable substances, for example, a biological treatment method and a wet oxidation method are known. Of these, biological treatment requires a long time to decompose oxidizable substances in wastewater, and only low-concentration wastewater can be treated. There is a need,
For these reasons, there is a disadvantage that the facility area of the processing facility becomes large. Moreover, since the microorganisms used are greatly affected by the temperature and the like, it has been difficult to continue stable operation.

[0003] On the other hand, the wet oxidation method is a method in which wastewater is treated at a high temperature and high pressure and in the presence of oxygen to oxidize and / or decompose oxidizable substances in the wastewater. In this method, as a means for increasing the reaction rate and relaxing the reaction conditions, for example, a catalyst wet oxidation method using a catalyst using an oxide or a catalyst combining these oxides with a noble metal element or the like has been proposed.

However, in order to purify the wastewater by oxidizing and / or decomposing various oxidizable substances contained in the wastewater by this method, it is necessary to treat the wastewater at a treatment temperature of 170 ° C. or more. The processing pressure is also 1 MPa (Gau
In many cases, pressures in excess of (ge) were required. For example, Japanese Patent Application Laid-Open No. H11-347574 proposes a method of performing wet oxidation treatment of acetic acid at a treatment temperature of 170 ° C. using a catalyst in which platinum is supported on titania. There has been a demand for a method for treating wastewater which requires treatment conditions, is capable of advanced treatment of wastewater, and is a treatment condition of low temperature and low pressure.

[0005] From the above, the present inventors have conventionally studied the development of a new catalyst and a new treatment method. As a result, as one of the means capable of further reducing the reaction conditions, when a solid catalyst containing activated carbon is used, 1
It was confirmed that the compound has a specific high activity with respect to organic and inorganic oxidizable substances under a low-temperature and low-pressure treatment condition of less than 70 ° C.

However, when a conventional solid catalyst containing activated carbon is used, there is a problem that the activated carbon itself burns under the conventional wet oxidation conditions. Therefore, the activated carbon must be put into practical use as a catalyst for wet oxidation. Was impossible. That is, when a conventional catalyst containing activated carbon is used, 17
When used at a treatment temperature of 0 ° C. or higher, there are many problems with the heat resistance of the catalyst. Even if the catalyst exhibits high activity at the initial stage, it has been deteriorated in less than 100 hours of use. It was. Therefore, it has been impossible to commercialize such a catalyst. On the other hand, even at a processing temperature of less than 170 ° C., if the method of use is not sufficiently considered, in a conventional catalyst containing activated carbon, the activated carbon itself is burned by the supplied oxygen-containing gas, and it takes only 100 to several hundred hours. The catalyst deteriorated even after moderate use. For this reason, it was impossible to use the catalyst containing the activated carbon in a wet oxidation treatment apparatus for actually treating wastewater.

Japanese Patent Application Laid-Open No. H11-179378 describes a method of oxidatively decomposing an oxygen-containing organic compound having only one carbon atom at a temperature of 100 ° C. or less by using an activated carbon catalyst carrying a noble metal. However, it cannot be applied to the treatment of an organic compound or an inorganic compound having two or more carbon atoms. Further, the durability (heat resistance) of the noble metal-supported activated carbon catalyst has not been sufficiently studied.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to treat wastewater containing organic and / or inorganic oxidizable substances by a catalytic wet oxidation method. In this case, a catalyst for wastewater treatment capable of effectively and stably oxidizing and decomposing these substances, a method for producing such a catalyst, and efficient and stable treatment of wastewater at a relatively low temperature and a low pressure for a long period of time. It is an object of the present invention to provide a method of treating wastewater by a catalytic wet oxidation method that can be used.

[0009]

The wastewater treatment catalyst according to the present invention, which has achieved the above objects, comprises an organic and / or inorganic oxidizable substance contained in wastewater which is oxidized and / or oxidized by a catalytic wet oxidation method. Alternatively, it is a solid catalyst used in the decomposition treatment, which contains activated carbon and has the gist in that it contains the following component (a) and / or (b) as a catalyst component. Component (a): Ti, Zr, Hf, Nb, Ta, Fe, C
o, Mn, Al, Si, Ga, Ge, Sc, Y, La,
Ce, Pr, Mg, Ca, Sr, Ba, In, Sn, S
at least one element selected from the group consisting of b and Bi (b) component: Pt, Pd, Rh, Ru, Ir and Au
At least one element selected from the group consisting of

In the catalyst for wastewater treatment of the present invention, when the above component (a) is contained, the physical properties such as the pore volume and specific surface area having a pore diameter of 0.1 to 10 μm are determined by the physical properties of the raw material activated carbon. And the pore volume is 0.01 to 0.5 as compared with the pore volume of the raw material activated carbon.
ml / g or the specific surface area is
50 to 800 m ² / g compared to the specific surface area of the raw material activated carbon
It is preferred that it is reduced.

In producing the catalyst for wastewater treatment of the present invention, the activated carbon is mixed with the component (a) and / or (b).
The component may be supported and contained. However, when both the component (a) and the component (b) are contained, the component (a) is loaded on the activated carbon and then the component (b) is loaded. It is preferable to manufacture it. As a result, a catalyst form capable of maximizing the effect of the addition of the components (a) and (b) is obtained.

[0012] On the other hand, the wastewater treatment method of the present invention which can achieve the above object is to oxidize and / or decompose organic and / or inorganic oxidizable substances contained in wastewater by a catalytic wet oxidation method. At the time of treating the waste water, the oxygen-containing gas is supplied at a treatment temperature of 50 ° C. or more and 180 ° C. or less and a pressure at which the waste water retains a liquid phase.
The gist lies in the point that wastewater is treated using the wastewater treatment catalyst of the present invention as described above.

[0013] In the wastewater treatment method of the present invention, the oxygen concentration in the exhaust gas after treating the wastewater with a catalyst is 0 to 0.
It is preferable to operate while maintaining the range of 5 vol%.
In order to maintain the oxygen concentration in the above range, the oxygen concentration in the exhaust gas is monitored by an oximeter, and the supply amount of the oxygen-containing gas is adjusted or controlled according to the fluctuation. Is desirable.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have studied from various angles in order to realize an optimum catalyst for use in a wet oxidation method. As a result, a solid catalyst containing the above component (a) and / or (b) as a catalyst component in activated carbon exhibits sufficient catalytic activity to oxidize and decompose oxidizable substances. And completed the present invention.

The catalyst of the present invention comprises the component (a) or (b)
Although the catalyst component is contained as a catalyst component, such a catalyst has improved heat resistance as compared with a catalyst comprising only activated carbon. Such an effect can be exhibited only by adding either one of the above-mentioned components (a) and (b) to the activated carbon. However, by including both the components, the heat resistance is remarkably improved.

The catalyst of the present invention prevents a decrease in catalyst strength after wastewater treatment and also makes it difficult to reduce the amount of catalyst due to combustion or powdering of activated carbon. Further, the oxidation resistance of the catalyst surface (activated carbon surface) is improved, and in particular, catalyst deterioration due to oxidation can be prevented. By the synergistic effect, the catalyst for wastewater treatment of the present invention can maintain a high efficiency of oxidizing and decomposing a substance to be oxidized contained in wastewater for a long time.

In the catalyst of the present invention, the activated carbon contains the component (a) and / or the component (b) as a catalyst component as described above, and the component (a) is a catalyst (activated carbon). Has the effect of improving oxidation resistance and preventing catalyst deterioration due to oxidation. Thereby, the conventional (a)
The wastewater can be treated at a higher temperature as compared to a catalyst containing no component. Further, it is possible to treat wastewater even under a condition where the amount of oxygen-containing gas is larger. Therefore, not only the wastewater treatment performance can be improved and the wastewater can be treated with higher purification performance, but also the durability of the catalyst can be improved and the wastewater treatment cost can be reduced. Also, (b) described later.
When the components are simultaneously contained, the catalytic activity of the component (b) can be improved, and high catalytic activity can be exhibited even with a small amount of the component (b). Specifically, the component (b) can be more supported on the catalyst surface, and the component (b) can be more highly dispersed, and the re-aggregation and migration of the component (b) can be prevented. . That is, it exhibits an effect as a cocatalyst having actions such as improvement of catalytic activity and improvement of durability.

The content of the component (a) (content based on the whole catalyst) is not particularly limited, but is preferably 0.1 to 10% by mass, more preferably 0.3 to 7% by mass, and more preferably 0.3 to 7% by mass in the solid catalyst. Preferably, the content is about 0.5 to 5% by mass. When the content of the catalyst (a) component is less than 0.1% by mass, the above effect of containing these elements is hardly exhibited, and when it exceeds 10% by mass, the surface of the activated carbon as a carrier is covered, and the specific Surface area and pore volume are reduced. In addition, it becomes difficult to prevent the component (b) from reaggregating and moving. For these reasons, the adsorption performance of the oxidizable substance or oxygen is reduced, or the component (b) is taken into the component (a), and the activity of the catalyst is rather lowered.

Among these components (a), Ti, Zr, Fe, Mn, Ce and Pr are preferable in terms of characteristics.
And more preferred elements are Ti, Zr and Fe, and still more preferred are Ti and Zr. The form of these elements contained in the catalyst is not particularly limited as long as it is a metal and / or a compound of the metal, and is preferably a metal or compound insoluble or hardly soluble in water. And more preferably a metal, oxide or composite oxide insoluble or hardly soluble in water.

On the other hand, the component (b) exerts an effect of expressing a main catalytic activity for oxidizing and decomposing an oxidizable substance as a main active component of the catalyst. The content of these elements (content based on the entire catalyst) is not particularly limited,
The content is preferably about 0.05 to 2% by mass, more preferably about 0.1 to 1% by mass in the solid catalyst. When the content of the component (b) is less than 0.05% by mass,
The effect of containing these elements is hardly exhibited, and if it exceeds 2% by mass, the cost is increased and the cost of the catalyst is undesirably increased.

Among these components (b), Pt, Pd, and Ru are preferable in terms of characteristics, more preferable elements are Pt and Pd, and further preferable is Pt.
It is. The form of these elements contained in the catalyst is not particularly limited as long as it is a metal and / or a compound of the metal, but is preferably a metal and / or an oxide, more preferably Metal.

The solid catalyst of the present invention contains activated carbon as a main component in addition to the component (a) and / or the component (b). The type of the activated carbon is not particularly limited, and examples thereof include those made from charcoal, coconut shell charcoal, coal, coke, peat, lignite, pitch, and the like, and acrylonitrile-based activated carbon fibers and Carbon fiber-based activated carbon such as phenol-based activated carbon fiber, cellulose-based activated carbon fiber, and pitch-based activated carbon fiber may be used. Among them, preferred activated carbon is one made from charcoal, coconut shell, and peat, and more preferred is one made from coconut shell or peat.

The shape of the solid catalyst is spherical,
Various shapes such as a pellet, a ring, a crushed shape, a honeycomb, and the like can be used, but preferably a spherical shape or a pellet shape is used.

The physical properties of the catalyst of the present invention are not particularly limited, but preferably the sum of the pore volumes having pore diameters of 0.1 to 10 μm is 0.1 to 0.8 ml / g.
And a specific surface area of 100 to 2500 m ² / g. Further, the total volume of the pores having a pore diameter of 0.1 to 10 μm is more preferably 0.15 to 0.6 ml / g, and still more preferably 0.2 to 0.5 ml / g. . Further, those having a specific surface area of 400 to 1600 m ² / g are more desirable, and still more preferably 600 to 1200 m ² / g.
m ² / g, most preferably from 700 to 110
0 m ² / g. The reasons for these provisions are as follows.

In the wet oxidation treatment of the waste water, the macropore diameter of the catalyst pores of 0.1 to 10 μm greatly affects the diffusion of oxidizable substances and oxygen contained in the waste water. For this reason, a catalyst having a large pore diameter of 0.1 to 10 μm facilitates diffusion of the oxidizable substance and oxygen, so that the reaction proceeds easily. That is, the processing efficiency at low temperature and low pressure is improved. In contrast, a catalyst having a small pore diameter of 0.1 to 10 μm has poor diffusion of oxidizable substances and oxygen. This makes it difficult for the oxidizable substance to be adsorbed to the catalytically active sites, and the reaction does not proceed efficiently. In addition, oxygen is not used efficiently for the decomposition of the oxidizable substance, and the activated carbon itself is generated by excess oxygen. It becomes easy to burn. On the other hand, a catalyst having a very large pore diameter of 0.1 to 10 μm has a problem that the mechanical strength of the catalyst is reduced. For this reason, a catalyst in which the sum of the pore volumes having pore diameters of 0.1 to 10 μm is within the above range is desirable.

As the specific surface area of the catalyst increases, the adsorption of oxidizable substances contained in the wastewater increases, and the treatment efficiency of the wastewater tends to improve accordingly. For this reason, a catalyst having a small specific surface area is undesirable.
However, in the case of a catalyst having a very large specific surface area, there is a problem that the mechanical strength of the catalyst is reduced. Therefore, a catalyst having a specific surface area of the catalyst within the above-mentioned range is desirable.

The physical properties are mainly affected by the physical properties of the activated carbon, but when the activated carbon contains the component (a), the physical properties are slightly lower than those of the activated carbon. Therefore, in order for the catalyst itself to satisfy the above physical properties, it is necessary to appropriately select the activated carbon used in the present invention in consideration of such a decrease. Further, the amount of reduction is affected by heat treatment conditions and the like, and therefore, it is necessary to select heat treatment conditions so as to obtain an appropriate amount of reduction.

When the above-mentioned component (a) is contained in activated carbon, the amount of decrease in physical properties is specifically 0.01 to 0.5 ml / g in a pore volume having a pore diameter of 0.1 to 10 μm.
It is preferably a reduced value, more preferably 0.0
A reduced value of 5 to 0.4 ml / g and even 0.1
It is preferred to have a reduced value of ０．３0.3 ml / g. In the specific surface area is preferably a 50 to 800 m ² / g reduced value, more preferably 100~700m ² /
g, and more preferably 200 to 600 m ² / g.

As described above, the reason why the amount of reduction is preferable is that this value (the amount of reduction) hardly contributes to the oxidation / decomposition reaction of the oxidizable substance by using the pore portion of the activated carbon with the component (a). This is a value indicating that the activated carbon has been properly covered and the activated carbon having the physical property value considered from the physical property value of the catalyst and this value (reduction amount) is suitable for the catalyst. When the reduction amount of the pore volume is less than 0.01 ml / g and when the specific surface area is less than 50 m ² / g, there are many pore portions of the activated carbon which hardly contribute to the oxidation / decomposition reaction of the oxidizable substance. You are doing. For this reason, the activity and durability of the catalyst decrease. When the reduction amount of the pore volume is more than 0.5 ml / g and when the reduction amount of the specific surface area is more than 800 m ² / g, the activated carbon which easily contributes to the oxidation / decomposition reaction of the oxidizable substance is used. As a result, the activity of the catalyst is reduced.

The production of the catalyst for wastewater treatment of the present invention is not particularly limited as long as it is produced so that the catalyst contains activated carbon and the component (a) and / or the component (b).
For example, the component (a) and / or the component (b) may be supported on activated carbon, the component (a) and / or the component (b) may be mixed with the activated carbon, and then molded. ) Component and / or component (b) may be carried and contained. However, as the production method, a production method in which the component (a) and the component (b) are supported and contained in activated carbon is preferable.

The method for supporting the component (a) and the component (b) on the activated carbon includes, for example, a method of supporting the component (a) and then supporting the component (b), and a method of supporting the component (b). After that, there is a method of supporting the component (a) or a method of supporting both the components (a) and (b) at the same time. Preferably, the component (a) is supported on activated carbon, and then the component (b) is supported. Is carried out to produce a catalyst. This makes it possible to maximize the effect of the addition of the components (a) and (b), thereby exhibiting excellent catalytic properties. Although not all catalysts have been elucidated for the reason that the catalyst characteristics are improved by producing the catalyst according to such a procedure, it can be considered as follows.

After carrying the component (a) on activated carbon,
When the component (b) is carried, the component (a) is supported on the surface of the activated carbon or inside the pores of the activated carbon, and the component (b) has a further outer surface than the component (a). It is carried near and near the surface of the pores and on the surface of the component (a). That is, the activity of the catalyst can be greatly improved by the fact that the component (b) effectively exists near the outermost surface of the catalyst. That is, the action of the component (a) can prevent the component (b) from being carried deep in the pores that are unlikely to contribute to the oxidation / decomposition reaction of the oxidizable substance. Also, by distributing the component (a) on the surface of the activated carbon,
(B) It is also in a form that exhibits a function of a dispersing effect as a wall for preventing the components from aggregating and moving. Also,
The component (a) effectively sends oxygen to the component (b) to promote the oxidation / decomposition reaction of the oxidizable substance and to prevent the activated carbon from being oxidized / degraded by oxygen. With such an embodiment, the performance of each catalyst component is effectively exhibited.

On the other hand, when the component (a) is loaded after the component (b) is loaded, or when both components (a),
When (b) is simultaneously supported, the component (a) is supported and then the component (b) is supported.
The component (b) does not effectively exist on the catalyst surface, and the activity of the catalyst is slightly reduced.

In the method for producing a catalyst according to the present invention, the component (a) is first supported on activated carbon. At this time, it is effective to carry out a treatment for stabilizing the component (a). As such a stabilizing treatment, after the component (a) is supported on activated carbon by an impregnation-supporting method, an adsorption-supporting method, or a spray method, the catalyst precursor is subjected to a heat treatment (drying or firing).
It is effective to do. The atmosphere for this heat treatment may be an oxidizing atmosphere (for example, air or the like) or an inert gas atmosphere (for example, nitrogen or the like), but it is possible to prevent the activated carbon from being oxidized and deteriorated. Therefore, it is preferable to perform firing in an inert atmosphere. When firing in an oxidizing atmosphere such as in air, the temperature should be 80 to
The temperature is preferably about 500 ° C, more preferably 1 ° C.
About 50 to 400 ° C., more preferably 200 to 3 ° C.
It is about 00 ° C. When firing in an atmosphere of an inert gas such as nitrogen, the temperature is preferably about 80 to 600 ° C, more preferably about 150 to 500 ° C, and still more preferably about 200 to 450 ° C.

On the other hand, even after carrying the component (b), it is effective to stabilize this component by performing a treatment such as heat treatment. The atmosphere for this heat treatment is
The catalyst may be an oxidizing atmosphere such as air, an inert gas atmosphere (eg, nitrogen), or a reducing atmosphere (eg, a hydrogen-containing gas), but it is preferable that the component (b) is a metal. Hydrogen-containing gas is used from the viewpoint that the activity tends to be high, and the polar groups such as the hydroxyl group and carbonyl group of the activated carbon are removed, and the higher the hydrophobicity, the higher the catalytic activity tends to be. And firing in a reducing atmosphere. When firing in an oxidizing atmosphere or an inert gas atmosphere, the temperature is preferably about 80 to 400 ° C, more preferably 150 to 300 ° C.
It is about. When firing in a reducing atmosphere using a hydrogen-containing gas, the temperature is preferably about 150 to 600 ° C, more preferably about 200 to 500 ° C, and still more preferably about 250 to 450 ° C. still,
In order to stabilize the component (b), it is effective to perform the heat treatment as described above, but it is also possible to stabilize the component by using a reducing agent such as sodium borohydride.

When the component (a) or the component (b) is carried on activated carbon, the form of the compound containing the component (a) or the component (b) includes the component (a) or the component (b). The compound is not particularly limited as long as it is a compound, but is preferably a water-soluble compound, and more preferably an inorganic compound. Further, an emulsion, slurry, or colloidal compound may be used, and a simple substance may be used, and a suitable substance may be used as appropriate.

In the catalyst containing activated carbon according to the present invention, a catalyst excellent in adsorption performance for a component to be treated (oxidizable substance) tends to be a catalyst having high catalytic activity.
For this reason, as the physical property value of the catalyst containing activated carbon in the present invention, it is possible to increase the adsorption performance for the component to be treated (oxidizable substance). For example, when the component to be treated (oxidizable substance) in the wastewater is an organic substance, not only the adsorption performance of the organic substance itself but also the adsorption performance of the oxidizable substance generated by oxidizing and decomposing the organic substance. You can also. Further, when an organic substance having 2 or more carbon atoms is a component to be treated, the acetic acid is generally, but not limited to, easily remaining in the treatment liquid after the wet oxidation treatment. For this reason, catalysts made using activated carbon with excellent acetic acid adsorption performance,
It tends to be a catalyst having high catalytic activity for organic substances.
Conversely, when the component to be treated (oxidizable substance) is a cationic inorganic substance such as ammonia or hydrazine, a catalyst prepared using activated carbon having excellent ammonia adsorption performance has a catalytic activity against these. It tends to be a high catalyst. Further, although not particularly limited, activated carbon used for a catalyst having excellent adsorption performance for the component to be treated is:
There is a tendency that the activated carbon has excellent adsorption performance for the component to be treated. For this reason, in producing the catalyst according to the present invention, it is desirable to use, as the activated carbon to be used, activated carbon having excellent adsorption performance for the component to be treated.

In the present invention, “excellent in adsorption performance” means, for example, that the larger the amount of the target component per unit amount of activated carbon, the better the adsorption performance when expressed under the specific conditions. It is excellent. In addition, it is expressed by the adsorption rate of the target component per unit amount of activated carbon under a specific condition, and the higher the rate, the better the adsorption performance. This adsorption speed can be expressed by an initial adsorption speed or an arbitrary post-adsorption speed, and is not particularly limited. However, preferably, it is expressed by the initial adsorption rate. Particularly, when activated carbon having a high initial adsorption rate is used, the activity of the catalyst is high, and when it is converted into a catalyst, the catalyst tends to have excellent adsorption performance. .

The catalyst containing activated carbon in the present invention is
It can be defined by various physical property values as described above. However, the range of the physical property values not described above does not limit the range of the catalyst containing activated carbon according to the present invention. Other various physical property values include, for example, the amount of various functional groups, the amount of ash and impurities, the structural form of carbon, the acidity, the volume of pores other than macropores (mesopores, micropores, submicropores), and the like. There are ratios, values of the external specific surface area and the internal specific surface area, and those relating to the ratio.

The term "oxidizable substance" as used in the present invention means an organic and / or inorganic compound which can be purified by oxidation / decomposition treatment, and is also expressed as an organic compound, a sulfur compound, a nitrogen compound, or the like. Although not particularly limited, organic halogen compounds and organic phosphorus compounds may be used. Specifically, for example, methanol, ethanol, acetaldehyde, formic acid, acetone, acetic acid, propionic acid, tetrahydrofuran (T
Organic compounds such as HF) and phenol; ammonia, hydrazine, nitrite, dimethylformamide (DM
F), nitrogen compounds such as pyridine; sulfur compounds such as thiosulfate ion, sodium sulfide, dimethyl sulfoxide, and alkylbenzene sulfonate. These may be dissolved in water or may be present as suspended substances.

Next, the wastewater treatment method of the present invention, which efficiently treats wastewater using the above-described catalyst, will be described with reference to the drawings. FIG. 1 is a schematic explanatory view showing an example of the configuration of a processing apparatus for carrying out the method of the present invention, but the apparatus for carrying out the method of the present invention is not intended to be limited to such a configuration.

In FIG. 1, waste water sent from a waste water supply source (not shown) is sent to a heater 3 by a waste water supply pump 5 through a waste water line 6. After an oxygen-containing gas (for example, air) is introduced from an oxygen-containing gas supply line 8 and pressurized by a compressor 7, the supply amount of the oxygen-containing gas is adjusted by an oxygen-containing gas flow control valve 9 while the heater It is configured to be supplied to drainage just before 3. The waste water heated by the heater 3 is supplied to the upper portion of the reaction tower 1 together with the oxygen-containing gas while the pressure is measured by the pressure gauge PI on the gas-liquid inlet side to the reaction tower 1.

The reaction tower 1 is provided with an electric heater 2.
The inside of the reaction tower 1 is regulated by the electric heater 2.
It is configured to be kept at a temperature of. Also, the reaction tower
1 is filled with a solid catalyst layer (not shown) of the present invention.
Acidity contained in the wastewater supplied into the reaction tower 1
As the oxidizable substance passes through this solid catalyst layer, it oxidizes and
And / or decompose. In this solid catalyst layer
The space velocity of is not particularly limited, but usually,
0.1 hour space velocity per catalyst layer^-1~ 10hr^-1,
More preferably 0.2 hr^-1~ 5hr^-1Even more preferred
0.3 hours ^-1~ 3hr^-1What is necessary is to make it.
Space velocity is 0.1hr^-1If less, the wastewater treatment volume is low.
And excessive equipment is required, and conversely 10 hours^-1Beyond
Oxidizing and decomposing the wastewater.
And can not. In addition, this reaction tower 1 is an upper part of the reaction tower 1.
After supplying wastewater with oxygen-containing gas and treating it,
It is discharged from the bottom of the tower 1, and the gas in the catalyst layer
The liquid flow system is of the gas-liquid downward co-current flow type.

The treatment liquid after the wastewater is oxidized and decomposed is cooled by the cooler 4 through the post-treatment line 10 discharged from the bottom of the reaction tower 1, released from the pressure control valve 12 and discharged. You. The pressure control valve 12 controls the inside of the reaction tower 1 to a predetermined pressure based on the pressure detected by the pressure controller PC. Thereafter, the processing liquid is sent to the gas-liquid separator 11 to be separated into gas and liquid.

In the gas-liquid separator 11, the sent processing liquid is separated into a gas (exhaust gas) and a liquid (processing liquid), and the exhaust gas is discharged from a gas discharge line 13.
The processing liquid is discharged by a processing liquid discharge pump 14 through a processing liquid discharge line 15. In the gas-liquid separator 11,
The oxygen concentration in the exhaust gas is measured by the oximeter 16. The liquid level of the processing liquid in the gas-liquid separator 11 is detected by a liquid level controller LC, and the processing liquid discharge pump 14 is controlled so as to have a constant liquid level.

In the apparatus for carrying out the present invention, the number, type, shape, and the like of the reaction towers are not particularly limited, and may be a single-tube reaction tower or a multi-tube reaction tower used for ordinary wet oxidation treatment. And the like can be used. However, when the concentration of the wastewater is high, the amount of heat generated by the reaction increases. Therefore, it is preferable to use a multitubular, heat-removing reactor, and perform the treatment while removing generated heat. Conversely, even when the concentration of the wastewater is low, it is desirable to use a multitubular, heat-removing reactor, and to treat while supplying heat. Further, when a plurality of reaction towers are installed, any reaction towers can be arbitrarily arranged, for example, the reaction towers of various shapes are arranged in series or in parallel according to the purpose.

According to the method of the present invention, the treatment is carried out in a temperature range of 50 ° C. or more and 180 ° C. or less. This processing temperature is 5
When the temperature is lower than 0 ° C., it becomes difficult to efficiently perform the oxidation and decomposition treatment of organic and / or inorganic oxidizable substances. The treatment temperature is preferably higher than 80 ° C, more preferably higher than 100 ° C, and still more preferably higher than 110 ° C. Even when the treatment temperature is 100 ° C. or lower, advanced treatment of an organic compound having 1 carbon atom such as methanol, formic acid, and formaldehyde is possible, but for advanced treatment of an organic compound having 2 or more carbon atoms, Reaction temperatures in excess of 100 ° C. are often required. If the treatment temperature exceeds 180 ° C., the activated carbon itself tends to burn, which is not practical. For this reason, the processing temperature is preferably 17
0 ° C. or less, more preferably 160 ° C. or less, further preferably 150 ° C. or less, and most preferably 14 ° C. or less.
0 ° C. or less.

On the other hand, the treatment pressure may be any pressure at which the wastewater retains a liquid phase at the treatment temperature described above, but is usually from atmospheric pressure to about 1 MPa (Gauge). For example, when the treatment temperature is 50 to 95 ° C. or lower, the wastewater is often in a liquid state even at atmospheric pressure, and thus may be at atmospheric pressure from the viewpoint of economy. Pressing is preferred. When the treatment temperature exceeds 95 ° C., the waste water often evaporates under the atmospheric pressure.
It is preferable to apply pressure to about 0.2 to 1 MPa (Gauge). However, a pressure exceeding 1 MPa (Gauge) is not preferable from the viewpoint of economy. In addition, when the processing pressure is excessively increased, as in the case where the processing temperature is increased, the problem of combustion of the activated carbon itself is likely to occur. Also, the activity of the catalyst may be reduced. For this reason, when pressurizing, a pressure control valve 12 is provided at the outlet side of the wet oxidation treatment apparatus (reaction tower 1) as shown in FIG. 1 so that the wastewater can maintain a liquid phase in the reaction tower 1. It is desirable to appropriately adjust the pressure to a predetermined value according to the processing conditions. Further, in order to improve the processing performance and the durability of the catalyst, the fluctuation of the processing pressure should be within ± 20%, more preferably within ± 10%,
More preferably, it is better to control within ± 5%.

In the method of the present invention, it is preferable to maintain the oxygen concentration in the exhaust gas after treating the waste water in the range of 0 to 5 vol%. That is, by maintaining the oxygen concentration in the exhaust gas after the wet oxidation treatment in the range of 0 to 5 vol%, the wastewater can be treated with high efficiency, and the oxidizable substances in the wastewater can be efficiently removed for a long time. Can be disassembled. If the oxygen concentration in the exhaust gas exceeds 5 vol%, combustion of the activated carbon due to excess oxygen occurs, and stable treatment becomes difficult. Therefore,
Preferably, it is effective to treat the oxidizable substance in the wastewater in a state where oxygen capable of oxidizing and decomposing is not insufficient. For this purpose, the oxygen concentration in the exhaust gas is 0 vol%
It is desirable that the condition is close to the above and that oxygen is not deficient. When the amount of supplied oxygen is insufficient, the efficiency of wastewater treatment is reduced in proportion to the amount of oxygen supplied. However, when the amount of supplied oxygen is slightly short, the activity of the catalyst containing activated carbon may be rather increased, and the efficiency of treating wastewater may be further improved. In this case, the durability of the catalyst is most improved, and a long-term stable treatment can be performed. Therefore, the oxygen concentration in the exhaust gas after the wet oxidation treatment is preferably 0%.
It is desirable that it is -4 vol%, More preferably, it is 0-2 vol%, More preferably, it is 0-1 vol%.

In the present invention, when the amount of supplied oxygen is slightly insufficient, the activity of the solid catalyst containing activated carbon is rather increased, and the efficiency of treating wastewater is often improved. This may be due to the active points on the catalyst surface, for example, the active points of the activated carbon itself, and the Pt, Pd, Rh, R contained in the activated carbon.
It is conceivable that the element [the component (b)] such as u, Ir, and Au is in a reduced state, so that the activity is improved.
In addition, in a state of low oxygen, activated carbon is reduced to increase the hydrophobicity of the surface, especially when the oxidizable substance is an organic substance,
It is conceivable that the improvement of the adsorption performance of the oxidizable substance to the activated carbon enhances the wastewater treatment activity.

In the present invention, in order to maintain the oxygen concentration in the exhaust gas in the range of 0 to 5 vol%, the oxygen concentration in the exhaust gas is measured using the oxygen concentration meter 16 as shown in FIG. The supply amount of the oxygen-containing gas may be adjusted or controlled by the oxygen-containing gas flow control valve 9 based on the measured value. The oxygen concentration meter for measuring the oxygen concentration in the exhaust gas may be any one that can be used for ordinary oxygen measurement, and a commercially available oxygen concentration meter can be used. Examples of such an oxygen concentration meter include an oxygen concentration meter using an oxygen sensor made of zirconia, an oxygen dumbbell type oxygen concentration meter, a gas chromatograph, and the like, and these are not particularly limited by the method of use. Also, the method of adjusting or controlling the supply amount of the oxygen-containing gas is not particularly limited, and can be adjusted or controlled by, for example, the above-described oxygen-containing gas flow rate control valve 9, but may be other means. Of course.

When starting the treatment of the waste water, it is desirable to supply the oxygen-containing gas at an initial supply amount smaller than the most appropriate supply amount, and to carry out the treatment in a state where the oxygen amount is slightly insufficient. In this case, the oxygen concentration in the exhaust gas is 0 V
ol%. Thereafter, it is desirable to gradually set the supply amount of the oxygen-containing gas to the most appropriate amount. At this time, it is desirable to measure the oxygen concentration in the exhaust gas and adjust or control the supply amount of the oxygen-containing gas based on the result. It is also desirable to analyze the treatment liquid after treating the wastewater and refer to the result. This can prevent the catalyst from being deteriorated due to excessive supply of oxygen when starting the treatment of the wastewater. Furthermore, when performing wastewater treatment, by performing a little reduction treatment of the catalyst,
The activity of the catalyst may be improved. In addition, when the wastewater is actually treated, the concentration and components of the wastewater often change, but the change can be easily coped with. still,
When the treatment efficiency of the wastewater is low due to a small supply amount of the oxygen-containing gas, the wastewater can be recycled so that the treated liquid after the treatment is subjected to the treatment of the present invention again. The processing method of the processing liquid is not particularly limited.

In the present invention, the term "oxygen concentration in the exhaust gas after the wet oxidation treatment" means the oxygen concentration in the gas phase immediately after treating the waste water with a solid catalyst containing activated carbon. Is the oxygen concentration in the exhaust gas generated when the treatment liquid after the treatment of the waste water is subjected to the gas-liquid separation treatment as shown in FIG.

In the present invention, in order to effectively oxidize and decompose organic and / or inorganic oxidizable substances contained in wastewater, a predetermined amount of oxygen-containing gas is used in accordance with the actual treatment efficiency. Need to supply.

In the method of the present invention, the operation is preferably performed while maintaining the oxygen concentration in the exhaust gas in the range of 0 to 5 vol%. Oxygen amount] / [the required amount of oxygen in the wastewater when the wastewater treatment efficiency is maximized] (hereinafter, the value of this ratio may be referred to as “D value”) = 0.8 to 1.3.
It may be set to be twice as large. That is, the supply amount of the oxygen-containing gas (hereinafter, sometimes referred to as “oxygen supply amount”) is adjusted or controlled so that the D value represented by the above ratio falls in the range of 0.8 to 1.3. Thereby, the processing performance and the durability of the catalyst can be remarkably improved.

In the present invention, the “oxygen demand of the wastewater when the efficiency of the wastewater treatment is maximized” means the treatment temperature,
When only the oxygen supply amount is changed while the wet oxidation treatment conditions such as the treatment pressure, the LHSV, the air flow system, and the catalyst to be used are kept constant, the wastewater drainage when the treatment efficiency of the wastewater drainage is maximized Oxygen demand. Therefore, this D value is an index indicating the excess or deficiency of the oxygen supply amount when the wastewater is treated. As a specific example, the chemical oxygen demand (COD (C) when the wastewater is treated by changing the oxygen supply amount under an arbitrary wet oxidation treatment condition.
r)) When the treatment efficiency is 90% at the maximum, if the oxygen-containing gas is supplied at a ratio of O ₂ /COD=0.9, [the amount of oxygen in the supplied oxygen-containing gas] / [the amount of wastewater (D value) of wastewater oxygen demand when the treatment efficiency is maximized
Is 1.0. Moreover, the oxygen-containing gas is O ₂ / COD.
If supplied at a rate of = 1.0, the D value is 1.11. However, the denominator of the D value, “the oxygen demand of the wastewater when the wastewater treatment efficiency is maximized,” is not necessarily the same as the “oxygen supply amount when the wastewater treatment efficiency is maximized.” Absent. The oxygen supply amount exemplified above is O ₂ / COD (Cr)
= 0.9, COD (Cr) processing efficiency is 90%
, The oxygen supply amount and the “denominator of the D value” are the same. However, when the oxygen supply amount is O ₂ / COD (C
r) = 2.0, COD (Cr) treatment efficiency is 90
In some cases, the maximum is in%. The D value at this time is 2.22.

If the D value exceeds 1.3, the amount of supplied oxygen becomes larger than the actual amount of oxygen required for the oxygen / decomposition treatment, so that the activated carbon itself tends to burn due to excess oxygen. On the other hand, if the D value is less than 0.8, the amount of oxygen supplied becomes smaller than the amount of oxygen required for the oxidation / decomposition treatment of the oxidizable substance, and the treatment performance is lowered, which is not practical. The preferred range of the D value is about 0.9 to 1.2, and more preferably about 0.95 to 1.1.

"Effluent treatment efficiency" described in the "Oxygen demand of wastewater when the efficiency of wastewater treatment is maximized" according to the present invention means, for example, COD treatment efficiency, TOC treatment efficiency, nitrogen treatment of wastewater. Various treatment efficiencies, such as efficiency, BOD treatment efficiency, TOD treatment efficiency, or treatment efficiency of specific substances, can be adopted depending on the purification target of wastewater, and are not particularly limited.

The oxygen-containing gas that can be used in the present invention is not particularly limited as long as it is a gas containing oxygen molecules, and may be pure oxygen gas, oxygen-enriched gas, air or the like. It is preferable to use cheap air. 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 addition, pure oxygen gas and oxygen concentration 50vol
% Or more of the oxygen-enriched gas tends to cause the combustion of activated carbon in the present invention, and the activity of the catalyst often decreases. However, an oxygen-enriched gas having an oxygen concentration of less than 40 vol%, more preferably an oxygen-enriched gas having an oxygen concentration of less than 35 vol%, hardly causes combustion of activated carbon in the present invention and improves the solubility of oxygen in wastewater. In many cases, wastewater treatment performance is improved. The method for producing such an oxygen-enriched gas is not particularly limited,
Examples include a deep cooling method and production of an oxygen-enriched gas by PSA. In addition, a production method using an oxygen-enriched membrane is preferable from the viewpoint of safety, because it is inexpensive, easy in operation, and does not require an excessively high oxygen concentration. Further, instead of the oxygen-containing gas, a hydrogen peroxide solution or the like can be used.

In the present invention, the method of gas-liquid circulation in the catalyst layer filled with the catalyst is not particularly limited, and it is preferable that the oxygen concentration in the exhaust gas after the treatment be in the range of 0 to 5 vol%. In this case, the treatment can be carried out stably and efficiently, but a more preferable method is a method of flowing in a gas-liquid downward co-current flow as shown in FIG. By increasing the gas-liquid contact efficiency and increasing the amount of oxygen dissolved by flowing gas-liquid downward and in parallel, and improving the contact efficiency between the liquid and the catalyst, the processing efficiency is improved. it is conceivable that. Further, when gas-liquid is caused to flow in parallel, the liquid containing a large amount of the oxidizable substance comes into contact with the gas having a high oxygen concentration at the inlet portion of the catalyst layer, so that the combustion of the activated carbon itself is considered to be suppressed. On the other hand, in the method of flowing gas and liquid in countercurrent,
Conversely, since a gas having a high oxygen concentration comes into contact with the catalyst near the outlet of the catalyst layer of the liquid in which the amount of the oxidizable substance has decreased, the combustion of activated carbon tends to occur, and the activity of the catalyst often decreases.

In the method in which gas and liquid are caused to flow upward in a parallel flow, the wet oxidation treatment is carried out from atmospheric pressure to 1 MPa (Gauge).
In many cases where the processing is performed within the processing pressure range described above, it is desirable that the amount of supplied oxygen is 1.5 times or more, more preferably 2.0 times or more the theoretical oxygen demand, because the processing performance is improved. For this reason,
When the wastewater is treated using the catalyst containing the activated carbon according to the present invention, the oxygen concentration in the exhaust gas is 0 to 5 vol.
%, The processing performance may not be significantly improved. The above “theoretical oxygen demand” means that the oxidizable substance in the wastewater is oxidized and decomposed to oxidize and decompose water, carbon dioxide, nitrogen gas and other ash such as inorganic salts. It is the amount of oxygen.

In the present invention, the method for supplying the oxygen-containing gas is not particularly limited. For example, all the oxygen-containing gas may be supplied from just before the catalyst layer. Supply method.
When the oxygen-containing gas is supplied in a divided manner, the amount of oxygen at the catalyst layer inlet can be reduced as compared with the case where the entire amount of the oxygen-containing gas is supplied before the catalyst layer. For this reason, the combustion of the activated carbon itself can be further suppressed, and the activity of the catalyst may be further improved. This allows the catalyst to be used stably for a longer period of time,
Wastewater treatment efficiency can be maintained high. In addition, when the oxygen-containing gas is divided and supplied, the supply position may be one or more before the catalyst layer and in the middle of the catalyst layer.
In this case, the oxygen concentration before the oxygen-containing gas supply port in the middle of the catalyst layer is not particularly limited, but is preferably 0 to 5 vol%, more preferably 0 to 3 vol%. By suppressing the oxygen concentration in this way,
The catalyst can be used more stably.

When the oxygen-containing gas is divided and supplied, the oxygen concentration is measured in advance to supply the oxygen-containing gas in the middle of the catalyst layer, and the amount of the supplied oxygen-containing gas is determined based on the result. May be. The oxygen concentration of the oxygen-containing gas to be divided may be different, and is not particularly limited.

In the present invention, “oxidation / decomposition treatment” means
Oxidative decomposition treatment of acetic acid to carbon dioxide and water, decarboxylation treatment of acetic acid to carbon dioxide and methane, hydrolysis treatment of urea to ammonia and carbon dioxide, oxidative decomposition treatment of ammonia and hydrazine to nitrogen gas and water Examples include oxidation and oxidative decomposition treatment of dimethyl sulfoxide to ash such as carbon dioxide, water and sulfate ions, and oxidation treatment of dimethyl sulfoxide to dimethyl sulfone or methane sulfonic acid. In short, easily decomposable oxidizable substances are used. Means including various oxidation and / or decomposition such as treatment to decompose to nitrogen gas, carbon dioxide, water, ash, etc., decomposition treatment to reduce the molecular weight of hardly decomposable organic substances and nitrogen compounds, or oxidation treatment to oxidize is there.

In the present invention, 50 ° C.
Passing the above water through the catalyst layer is not preferable from the viewpoint of durability of the catalyst because the activated carbon itself burns. In addition, from the active side of the catalyst, the temperature of 50 ° C.
When the water operation is performed as described above, the treatment activity when the operation is switched to drainage is significantly reduced. For this reason, when the temperature in the apparatus is 50 ° C. or higher during the start-up and stop of the apparatus, it is necessary to supply or circulate a liquid containing an oxidizable substance in order to improve the durability and activity of the catalyst. . Therefore, it is desirable to replace the water containing the oxidizable substance with water at 50 ° C. or lower.

In the present invention, at the time of start-up, first, a solution containing a readily decomposable oxidizable substance, for example, a methanol-containing solution is introduced into the catalyst layer, and then heated to 50 ° C. or higher, preferably 80 ° C. or higher. By switching to wastewater to be treated and treating wastewater, the catalytic activity can be kept high. When the wastewater to be treated contains an easily decomposable oxidizable substance, the wastewater can be introduced into the catalyst from the beginning.

As a method for activating a catalyst having a reduced oxidation / decomposition treatment performance, a substance adsorbed on the catalyst is desorbed by performing heat treatment for a short time, or the catalyst is activated or decomposed. Can be reactivated. As the heat treatment temperature at this time, a temperature that is about 5 to 100 ° C. higher than the ordinary wastewater treatment conditions is appropriately selected, and it is preferable that the temperature is raised to preferably 10 to 60 ° C., more preferably about 15 to 40 ° C. However, it is necessary to carry out the reaction at a temperature lower than 200 ° C. When the temperature is higher than 200 ° C., on the contrary, the catalytic activity often decreases due to combustion of the activated carbon itself. Also, the time of the heat treatment is not particularly limited,
It is appropriately selected in about 100 hours, preferably 3 to 50 hours, more preferably about 5 to 24 hours.

As a method for activating a catalyst having reduced oxidizing / decomposing treatment performance, there is a method of carrying out a reduction treatment of the catalyst. Specifically, by supplying wastewater or a liquid containing an easily decomposable oxidizable substance to a catalyst containing activated carbon under a non-supply of oxygen-containing gas or under a condition of insufficient supply of oxygen-containing gas, heat treatment is performed. It is possible to reactivate the activity of the catalyst. The treatment temperature at this time may be the same as the ordinary wastewater treatment temperature or may be appropriately high, and is not particularly limited. However, if the oxidizable substance in the liquid is in the presence of oxygen, it is oxidized and decomposed. It is necessary to be at a temperature to be processed, and it is desirable to carry out the process at less than 300 ° C. The processing time is not particularly limited, either.
About 100 hours, preferably 3 to 50 hours.
Time, more preferably about 5 to 24 hours.

Further, in the present invention, an oxidizable substance such as an organic acid (acetic acid, etc.) or ammonia contained in the treated water after the catalytic wet oxidation treatment is subjected to reverse osmosis having a high desalting rate such as a polyamide-based composite membrane. It can be processed using a membrane. At this time, the liquid that has passed through the reverse osmosis membrane is wastewater containing almost no oxidizable substance, and can be subjected to advanced treatment. On the other hand, the non-permeated liquid of the reverse osmosis membrane contains oxidizable substances such as organic acids and ammonia in a concentrated manner, so that advanced wastewater treatment can be performed by performing wastewater treatment such as wet oxidation treatment again. It is.

In the present invention, the treated water after the catalytic wet oxidation treatment can be subjected to biological treatment. After carrying out the present invention, many of the harmful substances in the wastewater are decomposed,
The COD component and the like are considerably reduced. Moreover, since the COD component and the nitrogen compound in the treatment liquid after the treatment according to the present invention are very easily decomposed by the biological treatment, the burden on the biological treatment is very small. Becomes

In the present invention, as a method for further increasing the durability of the catalyst, the catalyst containing activated carbon is divided into a plurality of containers, packed in the reaction tower, and when these are extracted, the catalyst is also added to the containers. A method of extracting from the reaction tower in a filled state is exemplified. In the method for treating wastewater using a solid catalyst, an excessive amount of the catalytic reaction is more likely to occur at the inlet than at the outlet of the catalyst layer. For this reason, excessive heating (hot spots) or the like occurs locally particularly near the inlet portion, and the mechanical strength and activity of the catalyst are reduced. Therefore, by adopting a method in which the catalyst is placed in the reaction tower in a state of being filled in the container, it is not necessary to replace the entire amount of the catalyst in the reaction tower when replacing the catalyst. It is possible to use the catalyst for a longer period of time.

In the wastewater treatment method according to the present invention, the type of the solid catalyst layer of the wastewater treatment device may be a fluidized bed type (fluidized bed type). In the wet oxidation treatment using a solid catalyst, when using a catalyst containing activated carbon according to the present invention,
A fluidized-bed wastewater treatment apparatus can be more easily employed than in the case where a conventional solid catalyst is used. The fluidized-bed type wastewater treatment apparatus is less likely to generate a hot spot due to the reaction, and thus can perform a higher-concentration wastewater treatment than a fixed-bed type (fixed-bed type) apparatus. In addition, the treatment of waste water, which tends to cause deterioration of the catalyst containing activated carbon, is facilitated by the characteristics of the apparatus. This is because a fluidized bed type wastewater treatment apparatus can add a new catalyst or a recycled catalyst while extracting a deteriorated waste catalyst. Conventionally, in the wet oxidation treatment using a solid catalyst, as a cause of catalyst deterioration, there has been a problem that an active component in the solid catalyst moves behind a fixed bed. This problem can also be solved in a fluidized bed apparatus because the solid catalyst itself moves. In the case of fluidized bed type,
Since a fixed catalyst having a smaller particle diameter than a solid catalyst generally used can be employed, and the contact efficiency with gas and liquid can be further improved, the processing performance can be improved. In addition, in the case of a fluidized bed type, even a wastewater containing a small amount of solids, which was difficult to treat in a fixed bed type, can be treated because it is unlikely to cause a problem of clogging of a reaction tower. The range can be further expanded.

In the case of this fluidized bed type apparatus, although not particularly limited, the reaction column may be a single column or a plurality of columns, and in view of operability and equipment cost. Is preferably one tower. Although not particularly limited, the inside of the reaction tower may be a single chamber, but if the reaction tower is divided into a plurality of chambers (multistage) by a baffle plate or the like, the processing performance is further improved, and the operation It is also desirable from a control aspect.

The type of wastewater to be treated in the present invention is not particularly limited. For example, various industrial plants such as chemical plants, electronic component manufacturing equipment, food processing equipment, metal processing equipment, metal plating equipment, printing and plate making equipment, and photographic equipment. Wastewater, or wastewater from power generation facilities such as thermal power generation and nuclear power generation. Specifically, wastewater from EOG production equipment, alcohol production equipment such as methanol, ethanol, and higher alcohols, particularly aliphatic carboxylic acids and esters thereof such as acrylic acid, acrylic acid ester, methacrylic acid and methacrylic acid ester, or terephthalic acid And organic matter-containing wastewater discharged from a process for producing an aromatic carboxylic acid or an aromatic carboxylic acid ester such as terephthalic acid ester. Further, waste water containing a nitrogen compound such as amine, imine, ammonia and hydrazine may be used. Further, wastewater containing sulfur compounds such as thiosulfate ions, sulfide ions, and dimethyl sulfoxide may be used. It may be domestic wastewater such as sewage or human waste. Alternatively, wastewater containing harmful substances such as organic halogen compounds such as dioxins and fluorocarbons, diethylhexyl phthalate, and nonylphenol, and environmental hormone compounds may be used. Further, wastewater containing aldehydes such as formaldehyde may be used. At this time, the content of formaldehyde is preferably about 0.1 to 5% by mass.

Hereinafter, the operation and effect of the present invention will be more specifically described with reference to examples. However, the following examples do not limit the present invention, and may be changed without departing from the spirit of the preceding and the following. All are included in the technical scope of the present invention.

[0076]

EXAMPLES (Catalyst Preparation Example 1) For catalyst preparation, an average diameter of 4
mmφ, average length 5.5 mmL, specific surface area is 1200 m ^{2 /} g by the BET method, and the total volume of the pores having pore diameters of 0.1 to 10 μm (hereinafter abbreviated as “pore volume”).
Used a pelletized activated carbon carrier of 0.63 ml / g by a mercury intrusion method. The carrier was loaded with an aqueous solution of titanyl sulfate by impregnation, dried at 90 ° C. in a nitrogen atmosphere, and then calcined at 400 ° C. for 3 hours in a nitrogen atmosphere.

The obtained carrier was further impregnated with an aqueous solution of platinum nitrate by an impregnation preparation method, dried at 90 ° C. in a nitrogen atmosphere, and then subjected to a reduction calcination treatment at 300 ° C. for 3 hours using a hydrogen-containing gas to obtain a catalyst. Prepared. The main components and the mass ratio of the obtained catalyst (hereinafter, this catalyst may be referred to as “A-1”) are shown in Table 1 below. In addition, titanium and platinum were described as a composition and content in terms of metal. Also,
The average pellet strength of the catalyst “A-1” was 6.4 kg / particle, the BET specific surface area was 900 m ² / g, and the pore volume was reduced to 0.48 ml / g.

(Catalyst Preparation Examples 2 to 8) Using the same activated carbon pellet-shaped carrier as used in Catalyst Preparation Example 1 above,
Instead of titanyl sulfate, an aqueous solution of zirconyl nitrate (catalyst preparation example 2), iron nitrate (catalyst preparation example 3), manganese nitrate (catalyst preparation example 4), cerium nitrate (catalyst preparation example 5), praseodymium nitrate ( The same platinum nitrate aqueous solution as used in Catalyst Preparation Example 1 was used except that each of Catalyst Preparation Example 6), tin sulfate (Catalyst Preparation Example 7), and bismuth nitrate (Catalyst Preparation Example 8) were supported by the impregnation preparation method. Each catalyst was prepared in the same manner.

The main components and mass ratios of the obtained catalysts (hereinafter, these catalysts may be referred to as “A-2” to “A-8”, respectively) are shown in Table 1 below. In addition, catalyst A-2 ~
The average pellet strength of A-8 was almost the same as A-1, and the BET specific surface area and the pore volume were also reduced to almost the same extent.

(Catalyst Preparation Example 9) The same activated carbon pellet-shaped carrier as used in Catalyst Preparation Example 1 was used, and the carrier did not carry an aqueous solution of titanyl sulfate. A comparative catalyst was prepared in the same manner as in Catalyst Preparation Example 1, except that only an aqueous platinum nitrate solution was supported.

The obtained catalyst (hereinafter referred to as “A-
9 ") is shown in Table 1 below. The average pellet strength of catalyst A-9 was almost the same as that of A-1, and the BET specific surface area and the pore volume were almost the same as those of the activated carbon carrier.

(Catalyst Preparation Example 10) The same activated carbon pellet-shaped carrier as used in Catalyst Preparation Example 1 was used, and the same aqueous solution of titanyl sulfate as used in Catalyst Preparation Example 1 was supported on the carrier by the same method. However, a comparative catalyst was prepared in the same manner as in Catalyst Preparation Example 1, except that the platinum nitrate aqueous solution was not supported.

The obtained catalyst (hereinafter referred to as “A-1”
0 ") is shown in Table 1 below. The average pellet strength of catalyst A-10 was almost the same as that of A-1, and the BET specific surface area and the pore volume were also reduced to almost the same extent as A-1.

(Catalyst Preparation Examples 11 and 12) The same activated carbon pellet-shaped carrier as used in Catalyst Preparation Example 1 was used, and the same aqueous solution of titanyl sulfate as used in Catalyst Preparation Example 1 was used as the carrier in the same manner. And further replaced with an aqueous platinum nitrate solution, an aqueous palladium nitrate solution (catalyst preparation example 11),
Alternatively, each catalyst was prepared by supporting ruthenium nitrate (catalyst preparation example 12) in the same manner as in catalyst preparation example 1.

The main components and mass ratios of the obtained catalysts (hereinafter, these catalysts may be referred to as “B-1” and “B-2”, respectively) are shown in Table 1 below. The average pellet strength of catalysts B-1 and B-2 was almost the same as A-1, and the BET specific surface area and pore volume were also reduced to almost the same extent as A-1.

(Catalyst Preparation Examples 13 and 14) The same activated carbon pellet-shaped carrier as used in Catalyst Preparation Example 1 was used, and the carrier did not carry an aqueous solution of titanyl sulfate. A catalyst for comparison was prepared by supporting an aqueous solution of palladium nitrate in the same manner as in Catalyst Preparation Example 1 in the same manner as in Catalyst Preparation Example 1, and carrying an aqueous solution of ruthenium nitrate in the same manner as in Catalyst Preparation Example 1 in place of the aqueous solution of platinum nitrate in Catalyst Preparation Example 14. did.

The main components and mass ratios of the obtained catalysts (hereinafter, these catalysts may be referred to as “B-3” and “B-4”, respectively) are shown in Table 1 below. The average pellet strength of catalysts B-3 and B-4 was almost the same as that of A-1, and the BET specific surface area and pore volume were almost the same as those of the activated carbon carrier.

(Catalyst Preparation Examples 15 and 16) The same activated carbon pellet-shaped carrier as used in Catalyst Preparation Example 1 was used, and the same aqueous solution of titanyl sulfate as used in Catalyst Preparation Example 1 was used as the carrier. The catalyst was prepared by supporting the same method by changing the amount supported on the carrier, and further supporting the same aqueous solution of platinum nitrate used in Catalyst Preparation Example 1 by the same method.

The main components and mass ratios of the obtained catalysts (hereinafter, these catalysts may be referred to as “C-1” and “C-2”, respectively) are shown in Table 1 below. The average pellet strength of catalysts C-1 and C-2 was almost the same as A-1. The BET specific surface area of the catalyst C-1 was 1100
m ² / g, the pore volume was reduced to 0.55 ml / g, the BET specific surface area of the catalyst C-2 was reduced to 700 m ² / g, and the pore volume was reduced to 0.43 ml / g.

(Catalyst Preparation Examples 17 and 18) The same activated carbon pellet-shaped carrier as used in Catalyst Preparation Example 1 was used, and the same aqueous solution of zirconyl nitrate as used in Catalyst Preparation Example 2 was used as the carrier. The catalyst was prepared by supporting the same method by changing the amount supported on the carrier, and further supporting the same aqueous solution of platinum nitrate used in Catalyst Preparation Example 1 by the same method.

The main components and mass ratios of the obtained catalysts (hereinafter, these catalysts may be referred to as “C-3” and “C-4”, respectively) are shown in Table 1 below. The average pellet strength of catalysts C-3 and C-4 was almost the same as A-1. The BET specific surface area of the catalyst C-3 was 1100
m ² / g, the pore volume was reduced to 0.54 ml / g, the BET specific surface area of catalyst C-4 was reduced to 800 m ² / g, and the pore volume was reduced to 0.45 ml / g.

(Catalyst Preparation Example 19) The same aqueous titanyl sulfate solution and the same platinum nitrate aqueous solution as used in Catalyst Preparation Example 1 were mixed, and the mixed solution was subjected to the same activated carbon pellet molding support as used in Catalyst Preparation Example 1. After drying at 90 ° C. in a nitrogen atmosphere, a reduction-calcining treatment was further performed at 300 ° C. for 3 hours using a hydrogen-containing gas to prepare a catalyst.

The resulting catalyst (hereinafter referred to as “D-
1) are shown in Table 1 below. Incidentally, the average pellet strength of the catalyst D-1 was almost the same as that of the catalyst A-1, and the BET specific surface area and the pore volume were also reduced to almost the same level.

Example 1 Using the apparatus shown in FIG. 1, a treatment was performed for 500 hours under the following conditions. At this time, the reaction tower 1 has a diameter of 26 mmφ,
A 3000 mm long cylindrical one was used, and 1.0 liter (410 g) of the catalyst A-1 prepared in Catalyst Preparation Example 1 was filled therein. The wastewater subjected to the treatment was wastewater discharged from a chemical plant and contained many organic compounds such as acetic acid and propionic acid, and had a COD (Cr) concentration of 25 g / liter.

The method of treatment is as follows. The wastewater supplied through the wastewater supply line 6 is supplied to the wastewater supply pump 5 at 1 liter / liter.
After the pressurized feed at a flow rate of h, the mixture was heated to 130 ° C. by the heater 3 and supplied from the upper portion of the reaction tower 1, and was treated in a gas-liquid downward cocurrent flow. After air is introduced from the oxygen-containing gas supply line 8 and pressurized by the compressor 7, the flow rate is controlled by the oxygen-containing gas flow control valve 9 so that the oxygen concentration of the exhaust gas becomes 0.1 to 0.5%. Then, it was mixed with the wastewater before the heater 3.

In the reaction tower 1, the electric heater 2
The temperature was kept at 30 ° C., and oxidation / decomposition treatment was performed. After the treatment liquid was cooled by the cooler 4, the pressure was released from the pressure control valve 12 and separated by the gas-liquid separator 11. At this time, the pressure control valve 12 detects the pressure with the pressure controller PC,
The inside of the reaction tower 1 was controlled so as to maintain a pressure of 0.4 MPa (Gauge). Further, the oxygen concentration of the exhaust gas in the gas-liquid separator 11 was measured using the oxygen concentration meter 16, and the COD (Cr) concentration of the processing liquid in the gas-liquid separator 11 was also measured. When the temperature of the reaction tower 1 is raised, the wastewater is supplied to the reaction tower 1 under oxygen-deficient conditions to suppress catalyst deterioration,
After the temperature rose to the set temperature, the supply air amount was gradually increased.

The treatment results of the obtained wastewater are as shown in Table 1 below. The specific surface area, pore volume, pore size distribution, strength of the catalyst pellets, etc. of the catalyst after the wastewater treatment were determined before use. No particularly significant difference from the catalyst was observed.

Examples 2 to 19 Catalyst A-1 prepared in Catalyst Preparation Example 1 described in Example 1
In place of the catalysts A-2 to
Using A-10, B-1 to B-4 and C-1 to C-4, the same wastewater treatment was performed in the same manner as in Example 1.
The treatment results of the obtained wastewater are as shown in Table 1 below, and the specific surface area, pore volume, pore diameter distribution, catalyst pellet strength, etc. of the catalyst after the wastewater treatment are particularly different from those of the catalyst before the treatment use. No significant differences were observed.

Example 20 Catalyst A-1 prepared in Catalyst Preparation Example 1 described in Example 1
In place of the above, the same wastewater treatment was performed in the same manner as in Example 1, except that the catalyst D-1 prepared in Catalyst Preparation Example 19 was used. The treatment results of the obtained wastewater are as shown in Table 1 below,
In addition, no significant difference was observed in the specific surface area, pore volume, pore diameter distribution, catalyst pellet strength, and the like of the catalyst after the wastewater treatment with the catalyst before the treatment.

Example 21 Using the apparatus shown in FIG. 1 under the following conditions,
The wastewater was treated in the same manner as described above. At this time, the catalyst A-1 prepared in Catalyst Preparation Example 1 was added to the reaction tower 1 in an amount of 1.0%.
Liter was filled. The wastewater used for the treatment mainly contained formic acid and had a COD (Cr) concentration of 8000 mg / liter. The processing temperature is 95 ° C., the processing pressure is atmospheric pressure, and the oxygen concentration of the exhaust gas is 0.1 to
The supply amount of air was controlled so as to be 0.5%. The supply amount of the drainage was set to 0.75 liter / h. The COD (Cr) treatment efficiency of the obtained wastewater was 98%. Also,
Specific surface area, pore volume, pore size distribution,
No significant difference was observed between the catalyst before use and the strength of the catalyst pellets.

Example 22 Catalyst A-9 was replaced with Catalyst A-9 described in Example 21.
The same processing as in Example 21 was performed except that was used.
As a result, the COD (Cr) treatment efficiency of the obtained wastewater was 72%.
%Met. In addition, no significant difference was observed in the specific surface area, pore volume, pore diameter distribution, catalyst pellet strength, and the like of the catalyst after the wastewater treatment with the catalyst before the treatment.

Example 23 The same wastewater treatment was carried out by the same operation method as in Example 1 under the following conditions. The reaction tower 1 was charged with 1.0 liter of the catalyst A-1 prepared in Catalyst Preparation Example 1. Then, the processing temperature is 190 ° C. and the processing pressure is 2.5 MPa (Gauge).
The supply amount of air was controlled so that the oxygen concentration of the exhaust gas was 0.1 to 0.5%. In addition, the supply amount of wastewater is 2.
0 liter / h. COD (Cr) of the obtained wastewater
The processing efficiency was 100%.

After 500 hours, the processing temperature was raised to 13
0 ° C., the treatment pressure was changed to 0.4 MPa (Gauge), the supply amount of wastewater was changed to 1.5 liter / h, and the supply amount of air was adjusted so that the oxygen concentration of the exhaust gas became 0.1 to 0.5%. For 100 hours under the same conditions as in Example 1.

As a result, COD (Cr) of the obtained wastewater was
The processing efficiency was 89%. In addition, no significant difference was observed in the specific surface area, pore volume, pore diameter distribution, strength of the catalyst pellets, and the like of the catalyst after the wastewater treatment compared with the catalyst before the treatment. Furthermore, neither collapse of the catalyst shape nor reduction of the catalyst amount was observed.

Example 24 A catalyst C-2 was used in place of the catalyst A-1 described in Example 23.
The same processing as in Example 23 was performed, except that As a result, the COD (Cr) treatment efficiency of the wastewater at the treatment temperature of 190 ° C. was 100%. On the other hand, the COD (Cr) treatment efficiency at a treatment temperature of 130 ° C. (100 hours) is 93%,
The processing efficiency was the same as that of Example 12. In addition, no significant difference was observed in the specific surface area, pore volume, pore diameter distribution, strength of the catalyst pellets, and the like of the catalyst after the wastewater treatment compared with the catalyst before the treatment. Furthermore, neither collapse of the catalyst shape nor reduction of the catalyst amount was observed.

Example 25 A catalyst A-9 was used in place of the catalyst A-1 described in Example 23.
The same processing as in Example 23 was performed, except that was used.
As a result, COD (Cr) of wastewater at a treatment temperature of 190 ° C.
The processing efficiency was 100%. But after about 400 hours,
The outflow of the catalyst powder together with the treatment liquid from the liquid outlet of the wet oxidation treatment apparatus was gradually observed. Further, a pressure increase in the pressure gauge PI on the gas-liquid inlet side to the reaction tower 1 was also gradually observed.

After a lapse of 500 hours, the processing conditions were changed to a processing temperature of 130 ° C. and a processing pressure of 0.4 M in the same manner as in Example 17.
Pa (Gauge), supply amount of wastewater is 1.5 liter /
and the supply amount of air was controlled so that the oxygen concentration of the exhaust gas was 0.1 to 0.5. That is, processing was performed under the same conditions as in Comparative Example 1.

As a result, the COD (Cr) of the obtained wastewater was
The processing efficiency was 37%, which was lower than Comparative Example 1. Further, when the catalyst was extracted, collapse of the catalyst shape and a decrease in the amount of the catalyst were observed, and the specific surface area of the catalyst after the wastewater treatment was 70%.
0 m ² / g, the pore volume is reduced to 0.41 ml / g, the average pellet strength of the catalyst was also reduced to 5.1 kg / particle.

Example 26 The same wastewater treatment was carried out for 500 hours in the same manner as in Example 1 under the following conditions. At this time, the reaction tower 1 was charged with 1.0 liter of the catalyst A-2 prepared in Catalyst Preparation Example 2. Then, the supply amount of air was increased so that the oxygen concentration of the exhaust gas became 10 to 11%. That is, the process was performed under the same conditions as in Example 2 except that the air supply amount was changed.

The COD (Cr) treatment efficiency of the obtained wastewater was 87% both after 100 hours and after 500 hours.
And stable processing was possible. No significant differences were observed in the specific surface area, pore volume, pore diameter distribution, catalyst pellet strength, etc. of the catalyst after the wastewater treatment compared with the catalyst before the treatment. Furthermore, neither collapse of the catalyst shape nor reduction of the catalyst amount was observed.

Example 27 A catalyst A-9 was used in place of the catalyst A-2 described in Example 26.
The same processing as in Example 26 was performed, except that was used.
As a result, after 500 hours, the COD (Cr) treatment efficiency of the wastewater was 21%, which was much lower than that of Comparative Example 1.

After about 450 hours, the outflow of the catalyst powder together with the processing liquid was gradually observed from the liquid outlet of the wet oxidation apparatus, and the pressure gauge PI at the gas-liquid inlet side of the reaction tower 1 increased the pressure. Was also observed gradually. Further, when the catalyst was extracted, collapse of the catalyst shape and a decrease in the amount of the catalyst were observed. The specific surface area of the catalyst after wastewater treatment was reduced to 800 m ² / g, and the pore volume was reduced to 0.43 ml / g. The average pellet strength was also reduced to 5.5 kg / particle.

Example 28 Using the apparatus shown in FIG. 1 and under the following conditions,
The wastewater was treated in the same manner as described above. At this time, the catalyst A-1 prepared in Catalyst Preparation Example 1 was added to the reaction tower 1 in an amount of 1.0%.
Liter was filled. The wastewater used for treatment contains formaldehyde and methanol, and COD (Cr)
The concentration was 10,000 mg / liter. The processing temperature was set to 70 ° C., the processing pressure was set to the atmospheric pressure, and the supply amount of air was controlled so that the oxygen concentration of the exhaust gas was 1% or less. The supply amount of wastewater was 1.0 liter / h. COD (Cr) treatment efficiency of the obtained wastewater is 93%
Met. In addition, no significant difference was observed in the specific surface area, pore volume, pore diameter distribution, strength of the catalyst pellets, and the like of the catalyst after the wastewater treatment compared with the catalyst before the treatment.

[0114]

[Table 1]

[0115]

The present invention is configured as described above,
When treating wastewater containing organic and / or inorganic oxidizable substances, a wastewater treatment catalyst capable of effectively oxidizing and decomposing these substances can be realized. This catalyst is used to treat wastewater under appropriate conditions. By doing so, it is possible to efficiently and stably treat wastewater at a relatively low temperature and a low pressure for a long period of time.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one configuration example of a processing apparatus for performing a method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction tower 2 Electric heater 3 Heater 4 Cooler 5 Drainage supply pump 6 Drainage supply line 7 Compressor 8 Oxygen-containing gas supply line 9 Oxygen-containing gas flow control valve 10 Treatment liquid line 11 Gas-liquid separator 12 Pressure control valve 13 Gas Discharge line 14 Treatment liquid discharge pump 15 Treatment liquid discharge line 16 Oxygen concentration meter

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01J 23/644 B01J 35/10 301G 23/656 301H 23/89 37/02 101D 35/10 301 C02F 1 / 74 101 ZAB 37/02 101 B01J 23/64 104M C02F 1/74 101 23/56 301M ZAB 23/64 101M (72) Inventor Takaaki Hashimoto 992, Okihama, Nishioki, Aboshi-ku, Himeji-shi, Hyogo Prefecture 1 Nippon Shokubai F Term (reference) 4D050 AA13 AB07 BB01 BC01 BC02 BC05 BC06 BC07 BD06 BD08 4G069 AA03 AA08 BA04B BA05B BA06A BA06B BB02B BB04B BC09A BC10A BC12A BC13A BC16A BC17A BC18A BC22A BC22B BC23A BC50A BCBC BCA BCBC BC BC BC55A BC56A BC62B BC66A BC66B BC67A BC70A BC70B BC71A BC72A BC72B B C74A BC75A BC75B BD05A CA05 CA07 CA10 EC01X EC04Y EC05Y EC17X EC17Y FA01 FA02 FB19 FB30 FB44

Claims (6)

[Claims] 1. A solid catalyst used for oxidizing and / or decomposing organic and / or inorganic oxidizable substances contained in wastewater by a catalytic wet oxidation method. A waste water treatment catalyst comprising the component (a) and / or the component (b) as a catalyst component. Component (a): Ti, Zr, Hf, Nb, Ta, Fe, C
o, Mn, Al, Si, Ga, Ge, Sc, Y, La,
Ce, Pr, Mg, Ca, Sr, Ba, In, Sn, S
at least one element selected from the group consisting of b and Bi (b) component: Pt, Pd, Rh, Ru, Ir and Au
At least one element selected from the group consisting of 2. The pore volume having a pore diameter of 0.1 to 10 μm when the component (a) is contained is 0.01 to 0.5 ml / g as compared with the pore volume of activated carbon as a raw material.
The catalyst for wastewater treatment according to claim 1, wherein the catalyst is reduced. 3. The specific surface area when the component (a) is contained is 50 to 50 times smaller than the specific surface area of the raw material activated carbon.
800 m ² / g reduced as the wastewater treatment catalyst according to claim 1 or 2. 4. The method for producing the catalyst for wastewater treatment according to claim 1, wherein the component (a) is loaded on activated carbon and then the component (b) is loaded. A method for producing a catalyst for wastewater treatment. 5. An organic and / or inorganic oxidizable substance contained in the wastewater is oxidized and / or decomposed by a catalytic wet oxidation method to treat the wastewater at 50 ° C.
A treatment temperature of at least 180 ° C. and a pressure at which the wastewater retains a liquid phase, while supplying an oxygen-containing gas,
A method for treating wastewater, comprising treating wastewater using the catalyst for wastewater treatment according to any one of claims 3 to 7. 6. The operation is performed while maintaining the oxygen concentration in the exhaust gas after treating the wastewater in the range of 0 to 5 vol%.
The processing method described in 1.