JP2002126520A - Wastewater treatment catalyst and method for treating wastewater by using the catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a catalyst which can keep excellent catalytic activity for a long time when used in the wet oxidation treatment of wastewater and has high mechanical strengths, and to provide a method for performing the wet oxidation treatment of wastewater by using the catalyst. SOLUTION: There are provided a wastewater treatment catalyst wherein the catalytically active component is ruthenium or a compound thereof, and the support that carries the active component is a titanium-containing compound, and the support has a pore diameter vs. pore volume distribution having a main peak on the side of a smaller pore diameters and having a subpeak with a peak top lower than that of the main peak at a pore diameter larger than 8,000 Å and a method for performing the wet oxidation treatment of wastewater by using the catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for wastewater treatment and a method for wet oxidation of wastewater using the catalyst. Particularly, the present invention relates to a catalyst having high catalytic activity, which can be suitably used when performing wet oxidation treatment of waste water under heating and pressurizing conditions.

[0002]

2. Description of the Related Art Conventionally, biological treatment, combustion treatment, the Timmermann method, and the like are known as wastewater treatment methods.

[0003] As biological treatment, aerobic treatment such as activated sludge method and biofilm method, anaerobic treatment such as methane fermentation method, and combined treatment of aerobic treatment and anaerobic treatment have been conventionally used. . In particular, aerobic treatment using microorganisms is widely used as a treatment method for wastewater, but aerobic microorganism treatment involves complicated interactions of bacteria, algae, protozoa, etc., resulting in high concentrations of organic matter and nitrogen compounds. If wastewater containing such substances is subjected to aerobic microbial treatment, it is necessary to dilute the wastewater and adjust the pH in order to make the environment suitable for the growth of microorganisms. Since sludge is generated, excess sludge must be further processed, and there is a problem that the processing cost is increased as a whole.

[0004] Combustion treatment involves costs such as fuel costs, and has the problem that treating large amounts of wastewater significantly increases the treatment cost. In addition, there is a possibility that secondary pollution due to exhaust gas or the like due to combustion may occur.

[0005] The Zimmerman method treats wastewater under high temperature and high pressure in the presence of an oxygen-containing gas. However, in general, the treatment efficiency is low and a secondary treatment facility is required.

In particular, in recent years, pollutants contained in wastewater to be treated are diverse, and a high level of treated water quality has been demanded.

Therefore, various wastewater treatment methods have been proposed for the purpose of obtaining high-level treated water with high wastewater treatment efficiency. For example, a wet oxidation method using a solid catalyst (hereinafter abbreviated as "catalyst wet oxidation treatment method") has been attracting attention because it can obtain a high level of treated water quality and has excellent economic efficiency. . Various catalysts have been proposed to improve the processing efficiency and processing capacity of such a catalytic wet oxidation treatment method. For example, JP-A-49-445
No. 56 uses noble metals such as palladium and platinum as alumina,
Catalysts supported on carriers such as silica alumina, silica gel, and activated carbon have been proposed. Also, JP-A-49-94157
No. 2 proposes a catalyst made of copper oxide or nickel oxide.

However, in general, the components contained in the waste water are not single, but often contain nitrogen compounds, sulfur compounds, organic halogen compounds, etc. in addition to organic substances, and contain such various pollutants. These components could not be sufficiently treated even if the above-mentioned catalyst was used for treating wastewater. Further, the catalyst has a problem in durability because the strength of the catalyst decreases with time and the catalyst is crushed and pulverized, so that the catalyst is not sufficiently practical.

As a technique for improving the strength of a catalyst, for example, JP-A-58-64188 discloses a catalyst in which a spherical or cylindrical titania or zirconia carrier carries a noble metal such as palladium or platinum and a heavy metal such as iron or cobalt. Has been proposed. However, none of these catalysts has been sufficiently satisfactory in catalytic activity and durability.

Japanese Patent Application Laid-Open No. 10-99876 proposes a titania catalyst having a specific structure supporting ruthenium. However, although the catalyst has high durability, the treatment performance of wastewater is not sufficient, and it cannot be said that the catalyst has high catalytic activity.

[0011]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a catalyst which maintains excellent catalytic activity for a long period of time when performing wet oxidation treatment of waste water and has high mechanical strength. And a method for wet oxidation treatment of waste water using the catalyst.

[0012]

Means for Solving the Problems The present inventors exert excellent catalytic activity, maintain excellent catalytic activity even after long-term use, and have sufficient mechanical strength even after long-term use. As a result of diligent research on catalysts having a catalyst carrier and a catalytically active component containing a specific component, and a catalyst having a specific peak in the pore size distribution of the pore volume with respect to the pore size of the support, The inventors have found that the above-mentioned object can be achieved, and reached the present invention.

[0013] The catalyst of the present invention that can solve the above-mentioned problems includes:
The catalytically active component is ruthenium, or a compound containing ruthenium, the carrier supporting the catalytically active component is a compound containing titanium, and the pore diameter of the carrier and the pore volume distribution with respect to the pore having a smaller pore diameter. The wastewater treatment catalyst is characterized in that it has a main peak and a sub-peak having a pore diameter exceeding 8000 angstroms and a sub-peak lower than the main peak. In addition, the height of the peak top of the main peak is set to 100%, and the width of the pore diameter corresponding to 50% of the height of the peak top is desirably less than 0.7 in the log pore diameter. 90% volume ratio of main peak in pore volume distribution
It is recommended that this be done.

The present invention also relates to a method for wet-oxidizing waste water in the presence of a solid catalyst, the method comprising using the above-mentioned catalyst.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The catalyst of the present invention is a catalyst which can be suitably used for wet oxidation treatment of waste water, wherein the catalytically active component is ruthenium or a compound containing ruthenium, and the catalytically active component is The carrier to be supported is a compound containing titanium, and has a main peak on the smaller pore size side in the pore size and the pore volume distribution for the carrier,
The gist is to have a sub-peak having a peak top lower than the main peak at a pore diameter of more than 8000 Å.

In the present invention, the term "catalytically active component" means an action for increasing the rate of oxidation / decomposition reaction on oxides such as organic compounds and nitrogen compounds contained in wastewater (hereinafter sometimes referred to as "active action"). Refers to components having. In the present invention, it is recommended to use ruthenium or a compound containing ruthenium as a catalytically active component having such an action, and a catalyst in which ruthenium or a compound containing ruthenium is used as the active component in combination with the following carrier is used as a wastewater. This is particularly preferred because it exerts particularly excellent activity in wet oxidation.

The carrier supporting the catalytically active component is preferably a compound containing titanium, and the carrier desirably has a relationship between a specific pore diameter and a pore volume as described later. More preferred carriers include titania, or a mixed oxide or composite oxide containing titania (eg, TiO ₂ —ZrO ₂ , TiO ₂ —Fe ₂ O ₃ , T
TiO ₂ —SiO ₂ , TiO ₂ —Al ₂ O ₃ , TiO ₂ —W
O ₃ , TiO ₂ —CeO ₂ , TiO ₂ —PrO ₂ , TiO ₂ —
MnO ₂ ) is also desirable from the viewpoint of the mechanical strength and durability of the catalyst. Further, a preferred carrier of the mixed oxide and / or the complex oxide containing titanium is a carrier containing at least one selected from the group consisting of iron, manganese, cerium, praseodymium, and zirconium, and titanium. Examples thereof include a mixed oxide and / or a composite oxide of titanium and at least one selected from the group consisting of iron, manganese, cerium, and zirconium.

As a combination of the above-mentioned catalytically active component and a carrier,
Is Ru-TiO_Two, Ru-Pd-TiO_Two, Ru-Rh
-TiO_Two, Ru-Ir-TiO_Two, Ru-Au-TiO
_Two, Ru-MnO_Two-TiO_Two, Ru-Pd-MnO_Two-T
iO_Two, Ru-MnO_Two-CeO_Two-TiO_Two, Ru-Ce
O_Two-TiO_Two, Ru-PrO_Two-TiO_Two, Ru-Pd-
PrO_Two-TiO_Two, Ru-TiO_Two-ZrO_Two, Ru-P
d-TiO_Two-ZrO_Two, Ru-Rh-TiO_Two-Zr
O_Two, Ru-Ir-TiO_Two-ZrO_Two, Ru-Au-T
iO_Two-ZrO_Two, Ru-Rh-TiO_Two-ZrO_Two, Ru
-Ir-TiO _Two-ZrO_Two, Ru-MnO_Two-TiO_Two−
ZrO_Two, Ru-Pd-MnO_Two-TiO _Two-ZrO_Two, R
u-MnO_Two-CeO_Two-TiO_Two-ZrO_Two, Ru-Ce
O_Two-TiO_Two-ZrO_Two, Ru-PrO_Two-TiO_Two-Z
rO_Two, Ru-CeO_Two-TiO_Two-ZrO_Two, Ru-Pr
O_Two-TiO_Two-ZrO_Two, Ru-Pd-PrO_Two-TiO
_Two-ZrO_Two, Ru-Fe_TwoO_Three-TiO_Two, Ru-Pd-
Fe_TwoO_Three-TiO_Two, Ru-Pr-Fe_TwoO_Three-TiO_Two,
Ru-Ir-Fe_TwoO_Three-TiO_Two, Ru-Au-Fe_TwoO
_Three-TiO_Two, Ru-Rh-Fe_TwoO_Three-TiO_Two, Ru-
MnO_Two-Fe_TwoO_Three-TiO_Two, Ru-Pd-MnO_Two−
Fe_TwoO_Three-TiO_Two, Ru-MnO_Two-CeO _Two-Fe_TwoO
_Three-TiO_Two, Ru-CeO_Two-Fe_TwoO_Three-TiO_Two, Ru
-PrO_Two-Fe_TwoO_Three-TiO_Two, Ru-CeO_Two-Fe_Two
O_Three-TiO_Two, Ru-PrO_Two-Fe _TwoO_Three-TiO_Two, R
u-Pd-PrO_Two-Fe_TwoO_Three-TiO_TwoIs exemplified
However, in the above combination examples, elements other than noble metals are generally stable
Oxides and noble metals were metals
And the combination of the catalytically active components of the present invention
It is not limited.

The content ratio of the catalytically active component constituting the catalyst of the present invention to the above-mentioned carrier supporting the catalytically active component is not particularly limited, but from the viewpoint of obtaining excellent catalytic activity, the content of the active component is preferably 0.01% by mass. % Or more, more preferably 0.1%.
It is preferably contained in an amount of at least 05% by mass, more preferably at least 0.1% by mass, preferably at most 3% by mass, more preferably at most 2% by mass, further preferably at most 1% by mass.

For example, when the catalyst is Ru—TiO ₂ , Ru
Is desirably 0.01% by mass or more and 3% by mass or less.

Although the catalytically active component of the present invention contains Ru, it is not limited to Ru alone, and may contain other elements or compounds thereof in any combination. For example, Pt, Pd , Rh, Ir, Au, alkali metals, alkaline earth metals, or other transition metals. Further, when a plurality of catalytically active components are contained, the catalyst preferably contains each of the catalytically active components in the above-mentioned ratio.

When the same element is used for both the catalytically active component and the catalyst carrier, the element may act as a catalytically active component, depending on the mechanism of action in wastewater treatment using the catalyst, Since it may not act as a component, when it does not act as a catalytically active component, the ratio is calculated as a carrier without using the above catalytically active component ratio.

The carrier of the present invention has a main peak on the side with a smaller pore diameter in the pore diameter of the carrier and the pore volume distribution with respect to the pore diameter, and has a minor peak on the side with a larger pore diameter lower than the peak top of the main peak. It is necessary that the peak has a peak and the position of the peak top of the sub-peak exceeds 8000 angstroms. With such a carrier, the activity of ruthenium can be remarkably improved as compared with the conventional case. As well as having sufficient mechanical strength, the catalyst of the present invention can maintain excellent catalytic activity for a long period of time and can be used.

In the present invention, the “peak top” is the maximum value when the pore diameter and the corresponding pore volume are graphed as shown in FIG.

In the pore diameter distribution curve, the pore diameter is divided into a finite number, the pore volume (V) between each of the pore diameters is measured, and the pore volume (V) is measured as the pore diameter (D ) May be a curve obtained by plotting the differential pore volume (ΔV / ΔD), which is a value differentiated by the above, with respect to the pore diameter. The axis is preferably a log pore diameter [logD, (μm)], and the vertical axis is preferably a log differential pore volume [微分 V / △ logD, (ml / g)]. Therefore, the peak top is the log pore diameter where the log differential pore volume is the largest with respect to the log pore diameter.

The pore volume of the main peak, assuming that the peak top of the peak is 100% as shown in FIG. 4, is the cumulative pore volume between pore diameters corresponding to 3% of the peak height. (In the pore diameter distribution curve of FIG. 4, the cumulative pore volume in the hatched portion). The pore volume of the other peaks other than the main peak is a fine volume equivalent to 3% of the main peak height when the peak height of the peak height is 10% or more of the peak top of the main peak. This is a value obtained by accumulating the pore volumes between the pore diameters. When the peak height of the peak height is less than 10% of the peak top of the main peak, the base line is sandwiched between the peaks and the absence of the peak. Is the sum of pore volumes between pore diameters higher than this baseline. However, when a plurality of peaks are overlapped, the range of the peak is defined as the pore diameter that is the minimum log differential pore volume between the valleys of the peaks.

In the present invention, the range of the pore diameter where the main peak is present is not particularly limited, but the pore diameter at the peak top of the main peak is preferably 500 Å or less, more preferably 400 Å or less, most preferably 300 Å or less. It is desirable that the compound be present, and the pore size at the peak top be 80 Å or more, from the viewpoint of obtaining excellent mechanical strength, durability and catalytic activity.

In the present invention, the sub-peak exists on the side where the pore diameter is larger than the main peak, and the range of the pore diameter where the peak top of the sub-peak exists is not particularly limited as long as it is 8000 Å or more. Is preferably 10,000 Å or more, more preferably 12,000 Å or more, preferably 10 μm or less, more preferably 5 μm or less.
m is recommended. It is preferable that the peak top of the sub-peak exists in such a range because the catalytic activity is remarkably improved, but it is not preferable that the sub-peak exceeds 10 μm because the mechanical strength of the catalyst may be reduced.

The number of peaks and the height of the peaks are not particularly limited. However, from the viewpoint of the mechanical strength, durability and catalytic activity of the catalyst, the carrier has only two peaks, ie, a main peak and a subpeak. It is preferred that the peak shape of the main peak is sharper, that is, the narrower the distribution width of the peak around the peak top of the main peak, the higher the mechanical strength, durability and catalytic activity. Is desirable.

In the present invention, the value of the peak top of the main peak is not particularly limited, and the peak having the largest log differential pore volume in the pore distribution curve is the main peak. Incidentally, peaks other than the main peak are not regarded as peaks when the log differential pore volume at the top of the peak is less than 1% of the volume of the main peak.

Depending on the distribution of the peaks, a so-called “shoulder type peak” having two peaks within the same peak may be obtained. As shown in FIG. 5, both peaks connecting the high peak and the low peak are formed. The minimum value (a) between the valleys is defined as a base line (a ′), and the base line (a ′) is 5% of the peak top (100%) of the high peak.
When it is less than 0% and the base line (a ') is less than 70% of the peak top (100%) of the low peak, it is regarded as a plurality of peaks. On the other hand, the base line (a ') has a high peak of 5% of the peak top (100%).
0% or more, and when the base line (a ') is less than 50% of the peak top of the high peak (100%), but the base line (a') is the peak top of the low peak (100%). ) Is one peak.

The crystal structure of the carrier is not particularly limited, and may have an anatase type crystal structure or a crystal structure other than the anatase type crystal structure. It is preferable from the viewpoint of.

In the present invention, from the viewpoint of improving the mechanical strength, durability and catalytic activity of the catalyst, the main peak has a sharper peak shape, that is, the distribution width of the peak around the peak top is narrow. Better mechanical strength,
It is desirable because durability and catalytic activity can be obtained. Specifically, when the height of the peak top of the peak is 100%, and the width of the pore diameter corresponding to 50% of the height of the peak top is less than 0.7 in the log pore diameter, the peak is sharp. Is preferred. More preferably the pore diameter is 0.6
Less than 0.5, more preferably less than 0.5, and most preferably less than 0.5.
It is less than 4. Similarly, it is desirable that the peak shape of the sub-peak is sharper because the catalytic activity becomes higher, and the width of the pore diameter is preferably less than 0.5, and more preferably 0.5.
It is less than 4, more preferably less than 0.35.

The "log pore diameter" is defined as logB when the pore diameter on the smaller pore diameter is A and the pore diameter on the larger pore diameter is B as shown in FIG. -LogA
In other words, in the present invention, it is preferable that logB-logA <0.7 as described above.

The pore volume of the carrier is not particularly limited, but is preferably 0.20 ml / g or more, more preferably 0.25 ml / g or more, and preferably 0.50 ml / g or less. Preferably 0.4
5 ml / g or less. If the pore volume is less than 0.20 ml / g, the catalytically active component cannot be sufficiently supported on the carrier, and the activity may be reduced. When the pore volume exceeds 0.50 ml / g, the durability of the catalyst may be reduced, and when used in a wet oxidation treatment, the catalyst may be prematurely disintegrated.

Furthermore, in the present invention, the pore volume of the main peak is preferably 90% or more, more preferably 93% or more, and more preferably the total pore volume (pore diameter 30 Å to 174 μm) of the carrier. It is desirable to be 99% or less from the viewpoint of improving the catalytic activity.

In the present invention, a mercury intrusion method is adopted as a method for measuring the pore size distribution of the pore size of the carrier. In the present invention, Shimadzu Autopore III
Using a Model 9420, the pore volume in the range of 0.003 to 413.7 MPa is measured. In addition, 0.003-0.
For the range of 1,724 MPa, when the pore distribution curve is graphed with the log pore diameter, the measurement is performed by dividing the measurement point into 17 parts so that the intervals between the measurement points are equal.
In the range of 3.7 MPa, similarly, when the pore distribution curve is graphed with the log pore diameter, the measurement is performed by dividing the measurement points into 60 so that the intervals between the measurement points are equal. This gives the pore diameter and the corresponding pore volume and log differential pore volume for the pore diameter range of 30 Å to 174 μm, with a pore diameter of 30 Å to 174 μm.
The value obtained by accumulating the pore volumes in the range of m is defined as the total pore volume of the present invention.

The shape of the catalyst (support) of the present invention is not particularly limited as long as it can be appropriately selected from shapes such as pellets, granules, spheres, rings, and honeycombs.

The preferred specific surface area of the catalyst is at least 20 m ² / g. When the specific surface area of the catalyst is less than 20 m ² / g,
The activity of the catalyst may not be sufficient. It is more preferably at least 25 m ² / g, most preferably at least 30 m ² / g. When the specific surface area exceeds 70 m ² / g, the catalyst is liable to disintegrate, and the activity of the catalyst may decrease.
In particular, when a catalyst having a specific surface area of more than 70 m ² / g is used for the wet oxidation treatment, the catalyst may be degraded at an early stage, and the catalyst activity may be deteriorated at an early stage. Therefore, the preferred specific surface area is 70 m ² / g or less, more preferably 60 m ² / g.
Or less, and most preferably 55 m ² / g or less.

In the present invention, the BET method for analyzing the adsorption of nitrogen is employed as a method for measuring the specific surface area of the catalyst. The BET specific surface area in the present invention is determined by Yuasa Ionics Co., Ltd.
Is a value measured by using a full-automatic surface area measuring device 4-Sorb manufactured by FUJIFILM Corporation.

The size of the catalyst is not particularly limited. For example, when the catalyst is granular (hereinafter sometimes referred to as “granular catalyst”), the average particle size is preferably 1 mm or more, more preferably 2 mm or more. It is. When a granular catalyst having an average particle size of less than 1 mm is packed in a reaction tower, the pressure loss increases, and the catalyst layer may be clogged by suspended matter contained in the wastewater. The average particle size of the granular catalyst is 10 m.
m or less, more preferably 7 mm or less. A granular catalyst having an average particle size of more than 10 mm may not have a sufficient geometric surface area, may lower the contact efficiency with the water to be treated, and may not be able to obtain a sufficient treatment capacity.

For example, when the catalyst is in the form of pellets (hereinafter sometimes referred to as “pellet catalyst”), the average diameter is preferably 1 mm or more, more preferably 2 mm or more, and preferably 10 mm or more. Or less, more preferably 6 mm or less. The length of the pellet-shaped catalyst in the longitudinal direction (may be expressed in mmL) is preferably 2 mm or more, more preferably 3 mm or more, preferably 15 mm or less, more preferably 10 mm or less.
mm or less. When a pelletized catalyst having an average diameter of less than 1 mm or a longitudinal length of less than 2 mm is filled in a reaction tower, pressure loss may increase, and an average diameter of more than 10 mm or a longitudinal length of 15 mm If the catalyst in the form of pellets having a particle diameter exceeding the above range cannot obtain a sufficient geometric surface area, the contact efficiency with the water to be treated may decrease, and a sufficient treatment capacity may not be obtained.

Further, when the catalyst is formed in a honeycomb shape (hereinafter, referred to as a honeycomb shape)
It may be referred to as "honeycomb-shaped catalyst". ), The equivalent diameter of the through hole is preferably at least 1.0 mm, more preferably at least 2.0 mm, and preferably at least 10 mm.
Or less, more preferably 6 mm or less. The thickness between adjacent through holes is preferably 0.1 mm or more, more preferably 0.3 mm or more, preferably 3 mm or less, more preferably 2.5 mm or less. Further, the porosity of the catalyst surface is preferably 50% or more, more preferably 55% or more, preferably 95% or less, more preferably 80% or less based on the total surface area. When a honeycomb catalyst having an equivalent diameter of less than 1.5 mm is packed in a reaction tower, pressure loss may increase. When a honeycomb-shaped catalyst having an equivalent diameter exceeding 10 mm is filled, the pressure loss is reduced, but the contact ratio with the liquid to be treated is reduced and the catalyst activity may be reduced. The thickness between the through holes is 0.
A honeycomb-shaped catalyst having a diameter of less than 1 mm has an advantage that the catalyst can be reduced in weight, but may sometimes lower the mechanical strength of the catalyst. Although the honeycomb catalyst having a thickness exceeding 3 mm has sufficient mechanical strength, the use of the catalyst raw material increases, and the cost may increase accordingly. The porosity of the catalyst surface is also desirably within the above range from the viewpoint of the mechanical strength and catalytic activity of the catalyst.

When the above-mentioned catalyst is filled in a reaction tower and the wastewater containing the suspended matter is subjected to wet oxidation treatment, the catalyst layer may be clogged by precipitation of solids and suspended matter in the wastewater. It is recommended to use a honeycomb catalyst among the above-mentioned catalysts.

The method for preparing the catalyst according to the present invention is not particularly limited, and can be easily prepared by a known method.

By employing the above-described structure for the catalyst, excellent catalytic activity and durability of the catalyst can be maintained for a long time, and high mechanical strength can be obtained. When the waste water is subjected to wet oxidation treatment using the catalyst of the present invention as described above, treated water purified to a high level can be obtained.

Hereinafter, a method for wet oxidation treatment of waste water using the catalyst of the present invention will be described in detail.

The type of wastewater treated by the wet oxidation treatment of the present invention is not particularly limited as long as the wastewater contains an organic compound and / or a nitrogen compound. Such wastewater is discharged from various industrial plants such as chemical plants, electronic component manufacturing equipment, food processing equipment, metal processing equipment, metal plating equipment, printing plate making equipment, photographic equipment, thermal power generation, nuclear power generation, etc. Effluent discharged from power generation facilities in Japan, specifically, EOG production facilities, wastewater discharged from alcohol production facilities such as methanol, ethanol and higher alcohols, especially acrylic acid, acrylates, methacrylic acid, methacrylates, etc. Organic effluents discharged from the production process of aliphatic carboxylic acids and esters thereof, or aromatic carboxylic acids such as terephthalic acid and terephthalic acid esters, and nitrogen such as amine, imine, ammonia and hydrazine Examples include wastewater containing a compound. For example, domestic wastewater such as sewage and human waste may be used. Or dioxins, fluorocarbons, diethylhexyl phthalate,
Wastewater containing harmful substances such as organic halogen compounds such as nonylphenol and environmental hormone compounds may be used.

[0049] The "drainage" in the present invention is not limited to the so-called industrial wastewater discharged from the industrial plant as described above, but may be any liquid containing an organic compound and / or a nitrogen compound. All are included,
The source of such a liquid is not particularly limited.

The catalyst of the present invention is used in a wet oxidation treatment. It is particularly recommended to use the catalyst in a case where the wastewater is heated and the catalyst is subjected to a wet oxidation treatment under a pressure at which the wastewater retains a liquid phase.

Hereinafter, a method of treating waste water using the treatment apparatus of FIG. 1 will be described. FIG. 1 is a schematic view showing an embodiment of a processing apparatus in a case where wet oxidation processing is employed as one of the oxidation processing steps, but the apparatus used in the present invention is not limited to this.

The wastewater supplied from the wastewater supply source is supplied to the wastewater supply pump 5 through the wastewater supply line 6 and further sent to the heater 3. The space velocity at this time is not particularly limited, and may be appropriately determined depending on the treatment capacity of the catalyst.

When the catalyst of the present invention is used, the wet oxidation treatment can be carried out in the presence or absence of an oxygen-containing gas. However, when the oxygen concentration in the wastewater is increased, the wet oxidation treatment is carried out. It is desirable to mix an oxygen-containing gas into the wastewater since the oxidation / decomposition efficiency of the oxides to be produced can be improved.

In the case of performing the wet oxidation treatment in the presence of the oxygen-containing gas, for example, the oxygen-containing gas is introduced from the oxygen-containing gas supply line 8, the pressure is increased by the compressor 7, and the wastewater is supplied to the heater 3. It is desirable to mix it into wastewater before.

In the present invention, the oxygen-containing gas is a gas containing oxygen molecules and / or ozone. If such a gas is used, pure oxygen, oxygen-enriched gas, air, hydrogen peroxide, other plants, etc. Oxygen-containing gas generated in
Although the type of the oxygen-containing gas is not particularly limited, it is recommended to use air among them from an economic viewpoint.

The supply amount of the oxygen-containing gas to the wastewater is not particularly limited, and may be any amount that is effective to enhance the ability to oxidize and decompose oxides in the wastewater. The supply amount of the oxygen-containing gas can be appropriately adjusted by, for example, providing the oxygen-containing gas flow control valve 9 on the oxygen-containing gas supply line 8. A preferable supply amount of the oxygen-containing gas is 0.5 times or more, more preferably 0.7 times or more, preferably 5.0 times or less, more preferably 3 times or more of the theoretical oxygen demand of the oxide to be discharged. .0
It is recommended that it be less than twice. When the supply amount of the oxygen-containing gas is less than 0.5 times, the oxide to be oxidized and decomposed may not be sufficiently oxidized and decomposed and may remain in the treatment liquid obtained through the wet oxidation treatment in a relatively large amount. Further, even if oxygen is supplied more than 5.0 times, the oxidation / decomposition treatment capacity may be saturated.

In the present invention, the term "theoretical oxygen demand" refers to the amount of oxygen necessary to oxidize and / or decompose oxides in wastewater to nitrogen, carbon dioxide, water and ash. In the present invention, the theoretical oxygen demand is indicated by the chemical oxygen demand (COD (Cr)).

The wastewater sent to the heater 3 is supplied to the reaction tower 1 after being preheated. If the temperature of the wastewater is too high, the wastewater is in a gas state in the reaction tower, so that organic substances and the like adhere to the surface of the catalyst, and the activity of the catalyst may be deteriorated. Therefore, it is recommended to apply pressure to the inside of the reaction tower so that the wastewater can maintain a liquid phase even at a high temperature. Although affected by other conditions, when the temperature of the wastewater exceeds 370 ° C. in the reaction tower, a high pressure must be applied to maintain the liquid phase state of the wastewater. The temperature of the waste water in the reaction tower is preferably 370 ° C. or lower, more preferably 270 ° C. or lower, and further preferably 23 ° C. or less, because the equipment may become large and the running cost may increase.
It is desirable that the temperature be 0 ° C. or lower, more preferably 170 ° C. or lower. On the other hand, if the temperature of the waste water is lower than 80 ° C., it may be difficult to efficiently perform the oxidation / decomposition treatment of the oxides in the waste water. Therefore, the temperature of the waste water in the reaction tower is preferably 80 ° C. or higher. The temperature is more preferably 100 ° C. or higher, and further preferably 110 ° C. or higher.

The timing of heating the wastewater is not particularly limited, and the previously heated wastewater may be supplied to the reaction tower as described above, or the wastewater may be heated after being supplied to the reaction tower. Good. There is no particular limitation on the method of heating the waste water, and a heater or a heat exchanger may be used, or the heater 2 may be installed in the reaction tower to heat the waste water. Further, a heat source such as steam may be supplied to the wastewater.

It is desirable to provide a pressure regulating valve on the exhaust gas outlet side of the wet oxidation treatment apparatus, and to appropriately adjust the pressure according to the treatment temperature so that the wastewater can maintain a liquid phase in the reaction tower. For example, when the treatment temperature is 80 ° C. or more and less than 95 ° C., the wastewater is in a liquid phase even at atmospheric pressure, and may be at atmospheric pressure from the viewpoint of economy. Pressing is preferred. When the processing temperature is 95
If the treatment temperature is 95 ° C or higher and lower than 170 ° C, the wastewater will often evaporate under atmospheric pressure.
When the pressure is about 0.2 to 1 MPa (Gauge) and the processing temperature is 170 ° C. or more and less than 230 ° C., 1 to 5 MPa
In the case where the pressure is about (Gauge) or the processing temperature is 230 ° C. or more, it is desirable to apply a pressure exceeding 5 MPa (Gauge) and control the pressure so that the wastewater can maintain a liquid phase.

In the wet oxidation treatment used in the present invention, the number, type, shape, and the like of the reaction towers are not particularly limited, and one or a plurality of reaction towers used for ordinary wet oxidation treatment can be used. For example, a single-tube reaction tower or a multi-tube reaction tower can be used. When a plurality of reaction towers are installed, they may be arranged arbitrarily, for example, in series or in parallel according to the purpose.

As a method of supplying the wastewater to the reaction tower, various forms such as gas-liquid upward cocurrent, gas-liquid downward cocurrent, gas-liquid countercurrent can be used, and a plurality of reaction towers are installed. In this case, two or more of these supply methods may be combined.

When the above-mentioned solid catalyst is used for the wet oxidation treatment in the reaction tower, the efficiency of the oxidation / decomposition treatment of the oxides such as organic compounds and nitrogen compounds contained in the wastewater is improved, and excellent long-term performance is obtained. The catalyst activity and the catalyst durability are maintained, and the wastewater can be obtained as a treated water purified to a high level.

The amount of the catalyst to be charged into the reaction tower is not particularly limited, and can be appropriately determined according to the purpose. Usually, the space velocity per catalyst layer is preferably 0.1 hr.
^-1 or more, more preferably 0.2 hr ^-1 or more, even more preferably 0.3 hr ^-1 or more, preferably 10 hr ^-1
Or less, more preferably 5 hr ^-1 or less, still more preferably 3 hr ^-1 or less.
It is recommended to adjust the catalyst loading so as to be no more than hr ^-1 . When the space velocity is less than 0.1 hr ^-1 , the treatment amount of the catalyst is reduced, and excessive equipment may be required. On the contrary, when the space velocity exceeds 10 hr ^-1 , the wastewater in the reaction tower is discharged. Oxidation / decomposition treatment may be insufficient.

In the case of using a plurality of reaction towers, different catalysts may be used respectively, or a reaction tower filled with a catalyst and a reaction tower not using a catalyst may be combined. The method is not particularly limited.

The shape of the catalyst to be filled is not particularly limited, but it is preferable to use a honeycomb catalyst.

In the reaction tower, various fillers, in-plant products, and the like may be incorporated for the purpose of agitation of gas and liquid, improvement of contact efficiency, reduction of gas and liquid drift, and the like.

The oxide to be oxidized in the waste water is oxidized and decomposed in the reaction tower. In the present invention, the term “oxidation and decomposition” means oxidative decomposition to convert acetic acid into carbon dioxide and water, and acetic acid to carbon dioxide. Decomposition treatment to convert dimethylsulfoxide to ash such as carbon dioxide, water and sulfate ions, hydrolysis treatment to convert urea to ammonia and carbon dioxide, ammonia and hydrazine to nitrogen gas and water Oxidation treatment to convert dimethyl sulfoxide to dimethyl sulfone or methanesulfonic acid, and the like, that is, nitrogen oxide,
Various oxidation and / or oxidation treatments such as a treatment to decompose carbon dioxide, water, ash, etc., a decomposition treatment to reduce the molecular weight of hardly decomposable organic compounds and nitrogen compounds, or an oxidation treatment to oxidize
Or the meaning including decomposition.

In the treatment liquid obtained through the wet oxidation treatment, the organic compound which is hardly decomposable among the oxides often remains in a low-molecular-weight state. In many cases, a low molecular weight organic acid, particularly acetic acid, remains as a compound.

After the wastewater is oxidized and decomposed in the reaction tower,
After being taken out of the processing liquid line 10 as a processing liquid and appropriately cooled by the cooler 4 as necessary, the gas-liquid separator 11
Is separated into gas and liquid. At that time, the liquid level controller LC detects the liquid level state, and the liquid level control valve 1
It is desirable to control the liquid level in the gas-liquid separator by means of 3 so as to be constant. Further, it is desirable to detect the pressure state using the pressure controller PC and control the pressure in the gas-liquid separator by the pressure control valve 12 so as to be constant.

Alternatively, after the oxidation / decomposition treatment of the waste water, the treatment liquid is discharged through the pressure control valve 42 without cooling, or after being cooled to some extent by the cooler 34 as shown in FIG. The liquid and the gas may be separated by the liquid separator 41.

The temperature in the gas-liquid separator is not particularly limited. However, since the processing liquid obtained by oxidizing and decomposing in the reaction tower contains carbon dioxide, for example, the gas-liquid separation It is desirable to release the carbon dioxide in the wastewater by raising the temperature inside the vessel, or to bubble the liquid separated by a gas-liquid separator with a gas such as air to release the carbon dioxide in the liquid .

To control the temperature of the processing liquid, a heat exchanger (not shown) and a cooler 4 are provided before the processing liquid is supplied to the gas-liquid separator 11.
Alternatively, the processing liquid may be cooled by a cooling means such as a heat exchanger (not shown) or a cooler (not shown) after gas-liquid separation.

The liquid (processing liquid) obtained by separation by the gas-liquid separator 11 is discharged from the processing liquid discharge line 15.
The discharged liquid may be further subjected to various known processes such as biological treatment and membrane separation treatment to further purify the liquid. Further, a part of the treatment liquid obtained through the wet oxidation treatment may be directly returned to the wastewater before being subjected to the wet oxidation treatment, or may be supplied to the wastewater from an arbitrary position in the wastewater supply line and subjected to the wet oxidation treatment. Is also good. For example, the treatment liquid obtained through wet oxidation treatment is used as dilution water for wastewater, and the TOD concentration and C
The OD concentration may be reduced.

The gas separated by the gas-liquid separator 11 is discharged from the gas discharge line 14 to the outside. still,
The discharged exhaust gas can be further subjected to another step.

In performing the wet oxidation treatment used in the present invention, a heat exchanger can be used for the heater and the cooler, and these can be used in an appropriate combination.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples do not limit the present invention, and all modifications that can be made without departing from the spirit of the present invention will be described. Included in the scope.

[0078]

EXAMPLES Catalyst Preparation Example 1 As a carrier used for catalyst preparation, a titania pellet-shaped carrier having a main peak and an auxiliary peak was used. The carrier has an average diameter of 5 mm, an average length of 6.5 mmL, an average compressive strength (average load obtained by applying a load to the carrier (catalyst) and breaking the carrier) is 3.1 kg / particle, and a specific surface area is a BET method. At 38
m ² / g, and the titania crystal structure of the molded carrier was anatase type. The carrier has a peak top of a main peak at 240 angstroms, the main peak has a pore diameter range of 100 to 400 angstroms, and a width of a pore diameter corresponding to 50% of the peak top height (100%). Was 0.21 in log pore diameter (hereinafter abbreviated as pore diameter width). In addition, the total pore volume (pore diameter 30
The volume ratio of the main peak to the total pore volume in the range of Angstroms to 174 μm: 0.38 ml / g) was about 93%. The sub-peak has a peak top at 15,000 angstroms, the pore diameter range of the sub-peak is 8000 to 25,000 angstroms, and the pore diameter width corresponding to 50% of the height (100%) of the peak top is 0.32. Was. The volume ratio of the sub peak to the total pore volume was about 5%. Then, a method of impregnating the carrier with an aqueous solution of ruthenium, which is a catalytically active component (after adding an aqueous ruthenium nitrate solution to absorb the aqueous solution,
Dry at 120 ° C, and further use a hydrogen-containing gas at 400 ° C
(A method of performing a baking treatment for 3 hours) with the catalyst (A-1)
I got The main component of the obtained catalyst (A-1) and the mass ratio thereof are TiO ₂ : Ru = 99.5: 0.5. The pore volume, pore size distribution, specific surface area, average compressive strength, and titania crystal structure of the catalyst were almost the same as those of the carrier used.

Catalyst Preparation Example 2 As a carrier used for preparing the catalyst, a titania pellet-shaped carrier having a main peak and a subpeak was used. The carrier has an average diameter of 5 mm, an average length of 6.5 mmL, and an average compressive strength of 3.
0 kg / grain, the specific surface area was 39 m ² / g by the BET method, and the titania crystal structure of the molded support was anatase type. In addition, the main peak has a peak top at 220 Å, and the pore diameter range of the main peak is 100 to
At 400 angstroms, the pore size width was 0.25. In addition, the total pore volume (pore diameter 30 angstrom to 1)
Total pore volume in the range of 74 μm: 0.40
(ml / g) was about 91% by volume. The sub-peak has a peak top at 9000 angstroms, and the pore size range of the sub-peak is 5,000 to 2,
0000 angstroms, and the pore diameter width was 0.36. The volume ratio of the sub-peak to the total pore volume is about 6%
Met. Then, a catalyst (A-2) having the same composition was obtained by the same method as that for preparing the catalyst shown in Catalyst Preparation Example 1. The pore volume, pore size distribution, specific surface area, average compressive strength,
The titania crystal structure was almost the same as the carrier used.

Comparative Preparation Example 1 As a carrier used for preparing the catalyst, a titania pellet-shaped carrier having a main peak and an auxiliary peak was used. The carrier has an average diameter of 5 mm, an average length of 6.5 mmL, an average pressing strength of 2.8 kg / particle, a specific surface area of 43 m ² / g by the BET method, and a titania crystal structure of the molded carrier of an anatase type. there were. The carrier has a peak top of a main peak at 280 angstroms, and the main peak has a pore size range of 100 to 500 angstroms and a pore size width of 0.35.
Met. Further, the total pore volume (total of the pore volumes existing in the range of pore diameter 30 Å to 174 μm:
0.40 ml / g), the volume ratio of the main peak to about 82
%Met. The minor peak has a peak top at 700 Å, and the minor peak has a pore diameter range of 500 Å.
~ 2000 angstroms, peak top height (1
(00%) was 0.52. The volume ratio of the sub-peaks to the total pore volume is about 13
%Met. Then, a comparative catalyst (A-3) was obtained in the same manner as in the catalyst preparation method shown in Catalyst Preparation Example 1. This A-3
And the mass ratio of TiO ₂ : Ru = 99.
5: 0.5. The pore volume, pore size distribution, specific surface area, average compressive strength, and titania crystal structure of the catalyst were almost the same as the carrier used.

Comparative Preparation Example 2 As a carrier used for preparing the catalyst, a titania pellet-shaped carrier having a main peak and an auxiliary peak was used. The carrier had an average diameter of 5 mm, an average length of 6.5 mmL, an average compressive strength of 2.6 kg / particle, a specific surface area of 44 m ² / g by the BET method, and the titania crystal structure of the molded carrier was anatase type. Was. Note that the main peak has a peak top at 320 Å, and the main peak has a pore size range of 130 Å.
８００800 Å and the pore diameter width was 0.55. In addition, the total pore volume (pore diameter 30 angstrom to 1)
Total pore volume in the range of 74 μm: 0.41
The volume ratio of the main peak to the total volume (ml / g) was about 60%. The sub-peak has a peak top at 2000 angstroms, and the pore size range of the sub-peak is 800 to 40.
00 angstroms, peak top height (100
%) Was 0.60.
The volume ratio of the sub peak to the total pore volume was about 30%. Then, a comparative catalyst (A-4) was obtained in the same manner as the catalyst preparation method shown in Catalyst Preparation Example 1. The main component of A-4 and its mass ratio are TiO ₂ : Ru = 99.5:
0.5. The pore volume, pore size distribution, specific surface area, average compressive strength, and titania crystal structure of the catalyst were almost the same as the carrier used.

Comparative Preparation Example 3 As a carrier used for preparing the catalyst, a titania pellet-shaped carrier having a main peak and an auxiliary peak was used. The carrier had an average diameter of 5 mm, an average length of 6.5 mmL, an average compressive strength of 2.5 kg / particle, a specific surface area of 42 m ² / g by the BET method, and the titania crystal structure of the molded carrier was anatase type. . The main peak has a peak top at 170 angstroms, and the main peak has a pore size range of 90 to 4.
It was 00 Å and the pore size width was 0.29. In addition, the total pore volume (pore diameter 30 angstrom to 1)
Sum of pore volumes existing in the range of 74 μm: 0.41
(ml / g) was about 86% by volume. The sub-peak has a peak top at 7000 angstroms, and the pore size range of the sub-peak is 3000 to 2
0000 angstroms, and the pore diameter width was 0.50. The volume ratio of the sub-peak in the total pore volume is about 9%.
Met. Then, a catalyst (A-5) was prepared in the same manner as in Catalyst Preparation Example 1. The pore volume, pore size distribution, specific surface area, average compressive strength and titania crystal structure of the catalyst were almost the same as those of the carrier used.

Catalyst Preparation Example 3 As a carrier (pellet) used for catalyst preparation, a shaped carrier containing a titanium oxide having a main peak and a subpeak and a composite oxide of titanium and zirconium was used. The carrier has an average diameter of 5 mm, an average length of 6 mmL, an average compressive strength of 4.3 kg / particle, and a specific surface area of 40 m ² / g by the BET method.
And the titania crystal structure of the carrier was an anatase type. The carrier has a peak top of the main peak at 220 Å, and the pore diameter range of the main peak is 80 Å.
５００500 Å and the pore diameter width was 0.30. In addition, the total pore volume (pore diameter 30 angstrom to 1)
Sum of pore volumes present in the range of 74 μm: 0.36
(ml / g) was about 94% by volume. The sub-peak has a peak top at 18,000 angstroms, and the pore size range of the sub-peak is 9000 to 8,000 angstroms.
30,000 angstroms, peak top height (1
(00%) was 0.34, and the volume ratio of the subpeak to the total pore volume was about 3%. Then, a catalyst (B-1) was obtained in the same manner as in the catalyst preparation method shown in Catalyst Preparation Example 1. The resulting catalyst (B-
The main component of 1) and its mass ratio are TiO ₂ : ZrO ₂ :
Ru = 80: 20: 0.3. The pore volume, pore size distribution, specific surface area, average compressive strength and titania crystal structure of the catalyst were almost the same as those of the carrier used.

Comparative Preparation Example 4 As the carrier (pellet-shaped) used in the preparation of the catalyst, a shaped carrier containing a titanium oxide having a main peak and a subpeak and a composite oxide of titanium and zirconium was used. The carrier has an average diameter of 5 mm, an average length of 6 mmL, an average compressive strength of 3.8 kg / grain, and a specific surface area of 43 m ² / g by the BET method.
And the titania crystal structure of the molded carrier was an anatase type. The main peak has a peak top at 300 Å, and the pore diameter range of the main peak is 100 Å.
５００500 Å and the pore diameter width was 0.45. In addition, the total pore volume (pore diameter 30 angstrom to 1)
Sum of pore volume existing in the range of 74 μm: 0.38
(ml / g) was about 88% by volume. The sub-peak has a peak top at 800 angstroms, and the pore size range of the peak is 500 to 3000.
The pore diameter width corresponding to 50% of the height of Angstrom and peak top (100%) was 0.55. The volume ratio of the auxiliary peak to the total pore volume was about 7%.
Then, a catalyst (B-2) was obtained in the same manner as in the catalyst preparation method shown in Catalyst Preparation Example 1. The main component and the mass ratio of the obtained catalyst (B-2) were TiO ₂ : ZrO ₂ : Ru = 8
0: 20: 0.3. The pore volume, pore size distribution, specific surface area, average compressive strength, and titania crystal structure of the catalyst were almost the same as the carrier used.

Catalyst Preparation Example 4 The carrier (pellet-shaped) used in the catalyst preparation had a main peak and a sub peak.
Titanium oxide, iron oxide and titanium having peaks
A molded carrier containing a composite oxide of iron and iron was used. The charge
The body has an average diameter of 3 mm, an average length of 5 mmL, and an average compressive strength.
The degree is 3.6kg / grain, the specific surface area is 43m by BET method.^Two/
g, and the titania crystal structure of the molded carrier is anatase
It was a mold. The carrier is mainly 170 angstrom.
Having a peak top of a peak, and a pore diameter range of the main peak
Is 80 to 400 angstroms and the pore diameter width is 0.26
Met. In addition, the total pore volume (pore diameter 30 ang straw)
Sum of the pore volumes present in the range of
0.37 ml / g), the volume ratio of the main peak to about 96
%Met. The secondary peak is 13000 angstrom.
And the sub-peak has a pore size range of 8
000-35,000 angstroms, peak top
The pore diameter width corresponding to 50% of the height (100%) is 0.4
It was 0. Also, the volume ratio of the sub-peak to the total pore volume
Was about 3%. The preparation of the catalyst shown in Catalyst Preparation Example 1
Catalyst (C-1) was obtained in the same manner as in the production method. Got
The main component of the catalyst (C-1) and the mass ratio thereof are Ti
O_Two: Fe_TwoO _Three: Ru = 40: 60: 1. In addition,
Catalyst pore volume, pore size distribution, specific surface area, average compressive strength
The titania crystal structure is almost the same as the carrier used.
Was.

Comparative Preparation Example 5 The carrier (pellet) used in the preparation of the catalyst was a molded carrier containing a titanium oxide having a main peak and a subpeak, an iron oxide, and a composite oxide of titanium and iron. Using. The carrier has an average diameter of 3 mm, an average length of 5 mmL, an average compressive strength of 3.3 kg / particle, and a specific surface area of 46 m ² / BET method.
g, and the titania crystal structure of the molded carrier was anatase type. The main peak has a peak top at 280 angstroms, and the pore diameter range of the main peak is 90 to
The thickness was 600 Å and the pore size width was 0.44. In addition, the total pore volume (pore diameter 30 angstrom to 1)
Sum of pore volumes existing in the range of 74 μm: 0.39
The volume ratio of the main peak to about 87 ml / g) was about 87%. The sub-peak has a peak top at 900 Å, and the sub-peak has a pore size range of 600 to 250 nm.
0 angstroms, peak top height (100%)
Was 0.50. The volume ratio of the auxiliary peak to the total pore volume was about 7%. Then, a catalyst (C-2) was obtained in the same manner as in the catalyst preparation method described in Catalyst Preparation Example 1. The obtained catalyst (C-2)
And the mass ratio of TiO ₂ : Fe ₂ O ₃ : R
u = 40: 60: 1. The pore volume, pore size distribution, specific surface area, average compressive strength and titania horizontal structure of the catalyst were almost the same as those of the carrier used.

Example 1 20 ml of the catalyst (A-1) and 200 ml of waste water were placed in a 1000 ml titanium autoclave equipped with a stirrer.
And air was introduced so as to have a pressure of 2.4 MPa (Gauge). Then, the temperature was raised to 160 ° C. while stirring at a stirring speed of 200 rpm.
Time drainage treatment was performed. The processing pressure at this time was 4.1.
MPa (Gauge). After the completion of the treatment, the autoclave was rapidly cooled and the treatment liquid was taken out. The wastewater used in the treatment was wastewater discharged from a process for producing an aliphatic carboxylic acid and an aliphatic carboxylic acid ester containing formic acid, formaldehyde, acetic acid and the like, and had a COD (Cr) concentration of 22 g / liter.

The treatment results of the obtained wastewater are shown in Table 1. The pore volume, pore size distribution, specific surface area, and titania crystal structure of the catalyst after the wastewater treatment are different from those of the catalyst (carrier) before the treatment. It was almost the same. However, the average compressive strength is 2.2.
kg / grain.

Example 2 The same wastewater treatment was performed in the same manner as in Example 1 except that the catalyst was changed to A-2. Table 1 shows the results. The pore volume, pore size distribution, specific surface area, and titania crystal structure of the catalyst after the wastewater treatment were almost the same as the catalyst (carrier) before the treatment. However, the average compressive strength was reduced to 2.1 kg / particle.

Comparative Examples 1 to 3 Except that the catalyst was changed to A-3, A-4, and A-5, respectively.
The same wastewater treatment was performed in the same manner as in Example 1. Table 1 shows the results. The pore volume, pore size distribution, specific surface area, and titania crystal structure of the catalyst after the wastewater treatment were almost the same as the catalyst (carrier) before the treatment. However, the average compressive strength was 1.7 kg / particle (A-3) and 1.5 kg / particle (A-
4), decreased to 1.6 kg / particle (A-5).

[0091]

[Table 1]

Example 3 Using the apparatus shown in FIG. 1, treatment was performed under the following conditions. The reaction tower 1 was cylindrical with a diameter of 26 mm and a length of 3000 mm, and was filled with 1.0 liter of the catalyst B-1 prepared in Catalyst Preparation Example 7. The wastewater subjected to the treatment was wastewater discharged from a chemical plant and contained a large amount of organic compounds such as alcohols, esters, and carboxylic acids.
The COD (Cr) of the wastewater was 30 g / liter.

The wastewater supplied through the wastewater supply line 6 is fed to the wastewater supply pump 5 at a flow rate of 3.0 liter / h, and then heated by the heater 3 to 240 liter / h.
Heated to ° C. and fed from the bottom of anti-response 1. Further, air is supplied from an oxygen-containing gas supply line 8 and the compressor 7
Then, the pressure is increased so that O ₂ / COD (Cr) (the amount of oxygen in the supply gas / the amount of chemical oxygen required in the wastewater) = 1.2.
The flow rate was controlled by the oxygen-containing gas flow control valve 9 and mixed into the wastewater before the heater 3. In the reaction tower 1, the treatment was performed in a gas-liquid upward parallel flow. In the reaction tower 1, the temperature was kept at 240 ° C. using the electric heater 2, and the oxidation and decomposition treatment was performed. The obtained processing liquid is passed through a processing liquid line 10 to a gas-liquid separator 11.
And gas-liquid separation. In the gas-liquid separator 11, the liquid level was detected by the liquid level controller LC, and the processing liquid was discharged from the liquid level control valve 13 so as to maintain a constant liquid level. The pressure control valve 12 detects the pressure with a pressure controller PC and outputs a pressure of 6.0.
Control was performed so as to maintain a pressure of MPa (Gauge) = 6.0.

The obtained wastewater treatment result was COD (Cr)
The treatment efficiency was 87%, and the pore volume, pore size distribution, specific surface area, and titania crystal structure of the butterfly after the wastewater treatment were almost the same as those of the catalyst (support) before the treatment. However, the average compressive strength was reduced to 2.4 kg / particle.

Comparative Example 4 The same wastewater treatment was performed in the same manner as in Example 3 except that the catalyst was changed to B-2. The treatment result of the obtained wastewater is C
The OD (Cr) treatment efficiency was 80%. The pore volume, pore diameter distribution, specific surface area, and titania crystal structure of the catalyst after the wastewater treatment were almost the same as those of the catalyst (carrier) before the treatment.
However, the average compressive strength was reduced to 1.9 kg / particle (B-2).

Example 4 Using the apparatus shown in FIG. 2, the treatment was performed under the following conditions. The reaction column 31 was a cylindrical shape having a diameter of 26 mm and a length of 3000 mm, and contained therein the catalyst C- prepared in Catalyst Preparation Example 10.
1.0 was filled. The wastewater used for the treatment was a solvent wastewater containing a large amount of alcohols such as ethyl alcohol and propyl alcohol. CO of the wastewater
D (Cr) was 35 g / liter.

The wastewater supplied through the wastewater supply line 36 is supplied to the wastewater supply pump 35 for 0.67 hours.
After the pressurized feed at a flow rate of 1 liter / h, the heater 33
At 165 ° C. and supplied from the upper part of the reaction tower 31.
Further, air is supplied from an oxygen-containing gas supply line 38 and pressurized by a compressor 37, and then O ₂ / COD (Cr)
The flow rate was controlled by the oxygen-containing gas flow rate control valve 39 so as to be 0.97, and was mixed into the wastewater before the heater 33. In the reaction tower 31, the treatment was performed in a gas-liquid downward co-current flow. In the reaction tower 31, the oxidation / decomposition treatment was carried out at 165 ° C. using the electric heater 31. The obtained processing liquid was cooled to 60 ° C. by the cooler 34 through the processing liquid line 40, and was released from the pressure control valve 42. The pressure control valve 42 detects the pressure with the pressure controller PC and outputs the pressure of 0.9 MPa.
(Gauge) pressure was controlled. The discharged gas-liquid was sent to a gas-liquid separator 41, where the gas-liquid was separated.

The treatment result of the obtained waste water is COD (Cr)
The treatment efficiency was 96%, and the pore volume, pore size distribution, specific surface area, and titania crystal structure of the catalyst after the wastewater treatment were almost the same as the catalyst (carrier) before the treatment. However, the average compressive strength was reduced to 2.2 kg / particle.

Comparative Example 5 The same wastewater treatment was performed in the same manner as in Example 4, except that the catalyst was changed to C-2. The treatment result of the obtained wastewater is C
The OD (Cr) treatment efficiency was 92%. The pore volume, pore size distribution, specific surface area, and titania crystal structure of the catalyst after the wastewater treatment were almost the same as the catalyst (carrier) before the treatment.
However, the average compressive strength was reduced to 2.0 kg / particle (C-2).

[0100]

Industrial Applicability The catalyst of the present invention has extremely excellent catalytic activity. In particular, the catalyst of the present invention can maintain excellent activity and durability for a long time during wet oxidation treatment of wastewater. . Moreover, when the wastewater is subjected to wet oxidation treatment using the catalyst of the present invention, treated water purified to a high level can be obtained.

[Brief description of the drawings]

FIG. 1 is an embodiment of a wet oxidation treatment apparatus according to the present invention.

FIG. 2 is an embodiment of a wet oxidation treatment apparatus according to the present invention.

FIG. 3 is a schematic diagram illustrating a peak top of the present invention.

FIG. 4 is a schematic diagram illustrating the peak pore volume of the present invention.

FIG. 5 is a schematic diagram illustrating a shoulder type peak of the present invention.

FIG. 6 is a schematic diagram illustrating the log pore diameter of the present invention.

[Explanation of symbols]

 1,31 Reaction tower 2,32 Electric heater 3,33 Heater 4,34 Cooler 5,35 Wastewater supply pump 6,36 Wastewater supply line 7,37 Compressor 8,38 Oxygen-containing gas supply line 9,39 Oxygen-containing gas Flow control valve 10, 40 Treatment liquid line 11, 41 Gas-liquid separator 12, 42 Pressure control valve 13 Liquid level control valve 14, 44 Gas discharge line 15, 45 Treatment liquid discharge line LC Liquid level controller PC Pressure controller

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunori Miyazaki 1-92, Nishioki, Okihama-shi, Aboshi-ku, Himeji-shi, Hyogo F-term (reference) 4D050 AA12 AA13 AB16 AB17 AB18 AB35 AB36 BB01 BC01 BC02 BC06 BD02 BD06 4G069 AA01 AA03 AA12 BA04B BA05B BB04B BC50B BC66B BC70A BC70B CA05 CA07 DA05 EC02Y EC09X EC09Y EC15Y EC17X EC18X EC18Y

Claims (4)

[Claims] 1. A catalyst used for a wet oxidation treatment of wastewater, wherein the active component of the catalyst is ruthenium or a compound containing ruthenium, the carrier supporting the catalytically active component is a compound containing titanium, and The carrier has a main peak on the smaller side of the pore diameter in the pore diameter and the pore volume distribution with respect thereto, and has a peak top of a sub-peak lower than the peak top of the main peak at a pore diameter of more than 8000 Å. Wastewater treatment catalyst. 2. The height of a peak top of the main peak is 1
2. The catalyst for wastewater treatment according to claim 1, wherein the width of the pore diameter corresponding to 50% of the height of the peak top is less than 0.7 in the log pore diameter. 3. The catalyst for wastewater treatment according to claim 1, wherein the volume ratio of the main peak in the total pore volume distribution is 90% or more. 4. A method for wet oxidation of wastewater in the presence of a solid catalyst, wherein the catalyst is the catalyst according to claim 1.