JP2002079091A - Catalyst for treating wastewater and wastewataer treatment method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst having excellent catalytic activity and durability over a long period of time at the time of wet oxidation treatment of wastewater and having high mechanical strength, and a wet oxidation treatment method for wastewater using the same. SOLUTION: The catalytically active component of the catalyst comprises at least one kind of an element, which is selected from the group consisting of manganese, iron, cobalt, nickel, cerium, chromium, praseodymium, copper, silver, gold, platinum, palladium, rhodium and iridium, or a compound containing at least one kind of the elements, and a carrier for supporting the catalytically active component contains at least one kind of an element selected from the group consisting of titanium, zirconium, silicon, aluminum, tungsten, iron, manganese, cerium and praseodymium. The catalyst has a main peak on a side small in pore size, in the pore size of the carrier and the pore volume distribution of the carrier, and has a sub-peak smaller than the main peak on a side large in pore size.

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. In particular, the catalyst of the present invention can be suitably used when performing wet oxidation treatment of waste water under high temperature and high pressure 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 and platinum and a heavy metal such as iron and cobalt. Has been proposed. However, none of these catalysts has been sufficiently satisfactory in catalytic activity and durability.

As a catalyst capable of solving these problems, the present inventors have already disclosed Japanese Patent Publication No. 3-34997 and Japanese Patent Laid-Open No. 5-1.
No. 38027 proposes a catalyst having high durability and excellent catalytic activity.

[0011]

DISCLOSURE OF THE INVENTION The present invention provides a catalyst which maintains excellent catalytic activity and durability for a long time in wet oxidation treatment of waste water and has high mechanical strength, and a wet type waste water treatment using the catalyst. An object of the present invention is to provide an oxidation treatment method.

[0012]

Means for Solving the Problems The present inventors have proposed a catalyst (Japanese Patent Publication No. 3-34997, Japanese Patent Application Laid-Open No. 5-138).
No. 027), which has better catalytic activity and durability than
As a result of intensive studies on a catalyst having high mechanical strength, the catalyst carrier and the catalytically active component contain a specific component, and have a specific peak in the pore size distribution of the pore volume with respect to the pore size of the support. Then, the inventors have found that the above-mentioned object can be achieved, and have reached the present invention.

[0013] The catalyst of the present invention that can solve the above-mentioned problems includes:
At least one element selected from the group consisting of manganese, iron, cobalt, nickel, cerium, chromium, praseodymium, copper, silver, gold, platinum, palladium, rhodium, and iridium; A carrier containing the above element, wherein the carrier supporting the catalytically active component is at least one or more elements selected from the group consisting of titanium, zirconium, silicon, aluminum, tungsten, iron, manganese, cerium, and praseodymium; Or a compound containing one or more elements, and has a main peak on the side with a small pore diameter in the pore diameter of the carrier and the pore volume distribution with respect thereto, and is smaller than the main peak on the side with a large pore diameter. This is a catalyst having a gist of having a sub-peak.

At this time, the peak top of the main peak is 5
It is preferable that the specific surface area is not more than 00 Å, and it is further recommended that the specific surface area of the catalyst be 20 to 70 m ² / g.

[0015] The present invention also relates to a method for wet oxidation of wastewater in the presence of a solid catalyst, the method comprising the use of the catalyst.

[0016]

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 manganese, iron, cobalt, nickel, cerium, chromium, praseodymium, copper , Silver, gold, platinum, palladium, rhodium and iridium, at least one element selected from the group consisting of or a compound containing one or more elements, wherein the carrier supporting the catalytically active component is
A compound containing at least one or more elements selected from the group consisting of titanium, zirconium, silicon, aluminum, tungsten, iron, manganese, cerium, and praseodymium, or a compound containing one or more elements; On the other hand, the catalyst is characterized in that it has a main peak on the side with a smaller pore diameter in the pore volume distribution and a sub-peak smaller than the main peak on the side with a larger pore diameter.

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, may be referred to as "active action"). Components such as manganese, iron, cobalt, nickel, cerium, chromium, praseodymium, copper, silver, gold,
It is recommended to use at least one or more elements selected from the group consisting of platinum, palladium, rhodium and iridium, or a compound containing one or more elements.

The above-mentioned catalytically active component preferably contains at least one or more elements selected from the group consisting of manganese, cerium, chromium, praseodymium, gold, platinum, palladium, rhodium and iridium, or one or more elements. It is a compound, more preferably a compound containing at least one element selected from the group consisting of manganese, cerium, gold, platinum, palladium, rhodium and iridium, or one or more elements. Still more preferably, the catalytically active component is at least one element selected from the group consisting of manganese, platinum, and palladium, or a compound containing one or more elements. Catalysts containing these catalytically active components are desirable because they exhibit particularly excellent activity in wet oxidation of wastewater.

In the present invention, the carrier supporting the catalytically active component is at least one element selected from the group consisting of titanium, zirconium, silicon, aluminum, tungsten, iron, manganese, cerium and praseodymium, or one or more elements. It is desirable that the carrier has a specific pore diameter and pore volume relationship as described later. Examples of the carrier include an oxide containing at least one selected from the group consisting of titanium, zirconium, silicon, aluminum, tungsten, iron, manganese, cerium, and praseodymium, and a composite oxide containing one or more. In particular, it is recommended that the carrier contains at least titanium or zirconium, and more preferably a carrier containing titania or a mixed oxide or composite oxide containing titania (for example, TiO ₂ —ZrO ₂ , TiO ₂ —Fe ₂ O ₃ , TiO ₂ -S
iO ₂ , TiO ₂ -Al ₂ O ₃ , TiO ₂ -WO ₃ , TiO ₂
—CeO ₂ , TiO ₂ —PrO ₂ , TiO ₂ —MnO ₂ ) are 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 Pt-TiO_Two, Pd-TiO_Two, Pt-Pd-Ti
O_Two, Pt-Rh-TiO_Two, Pt-Ir-TiO_Two, P
t-Au-TiO_Two, Pd-Rh-TiO_Two, Pd-Ir
-TiO_Two, Pd-Au-TiO_Two, MnO_Two-TiO_Two,
Pt-MnO_Two-TiO_Two, Pd-MnO_Two-TiO_Two, P
t-Pd-MnO_Two-TiO_Two, Pt-MnO_Two-CeO_Two
-TiO_Two, Pt-CeO_Two-TiO_Two, Pt-PrO_Two−
TiO_Two, Pd-CeO_Two-TiO_Two, Pd-PrO_Two-T
iO_Two, Pr-Pd-PrO_Two-TiO_Two, Pt-TiO_Two
-ZrO_Two, Pd-TiO_Two-ZrO_Two, Pt-Pd-T
iO_Two-ZrO_Two, Pt-Rh-TiO _Two-ZrO_Two, Pt
-Ir-TiO_Two-ZrO_Two, Pt-Au-TiO_Two-Z
rO_Two, Pd-Rh-TiO_Two-ZrO_Two, Pd-Ir-
TiO_Two-ZrO_Two, Pd-Au-TiO_Two-ZrO_Two, M
nO_Two-TiO_Two-ZrO_Two, Pt-MnO_Two-TiO_Two−
ZrO_Two, Pd-MnO_Two-TiO_Two-ZrO_Two, Pt-P
d-MnO_Two-TiO_Two-ZrO_Two, Pt-MnO_Two-Ce
O_Two-TiO_Two-ZrO_Two, Pd-MnO_Two-CeO_Two-T
iO_Two-ZrO_Two, Pt-CeO_Two-TiO_Two-ZrO_Two,
Pt-PrO_Two-TiO_Two-ZrO_Two, Pd-CeO_Two-T
iO_Two-ZrO_Two, Pd-PrO_Two-TiO_Two-ZrO_Two,
Pt-Pd-PrO_Two-TiO_Two-ZrO_Two, Pt-Fe_Two
O_Three-TiO_Two, Pd-Fe_TwoO_Three-TiO_Two, Pt-Pd
-Fe_TwoO_Three-TiO_Two, Pt-Pr-Fe_TwoO_Three−Ti
O_Two, Pt-Ir-Fe_TwoO_Three-TiO_Two, Pt-Au-F
e_TwoO_Three-TiO_Two, Pd-Rh-Fe_TwoO_Three-TiO_Two, P
d-Ir-Fe_TwoO_Three-TiO_Two, Pd-Au-Fe_TwoO_Three
-TiO_Two, MnO_Two-Fe_TwoO_Three-TiO_Two, Pt-Mn
O_Two-Fe_TwoO_Three-TiO_Two, Pd-MnO_Two-Fe_TwoO_Three−
TiO_Two, Pt-Pd-MnO_Two-Fe_TwoO_Three-TiO_Two,
Pt-MnO_Two-CeO_Two-Fe_TwoO_Three-TiO_Two, Pd-
MnO_Two-CeO_Two-Fe_TwoO_Three-TiO_Two, Pt-CeO_Two
-Fe_TwoO_Three-TiO_Two, Pt-PrO_Two-Fe_TwoO_Three−Ti
O_Two, Pd-CeO_Two-Fe_TwoO_Three-TiO_Two, Pd-Pr
O_Two-Fe_TwoO_Three-TiO_Two, Pt-Pd-PrO_Two-Fe_Two
O_Three-TiO_TwoEtc., but the combination example above is precious
Elements other than the genus are generally stable oxides and noble metals
Is only an example of a metal, and the catalyst of the present invention
The combination of the active ingredients is not limited to these.

The content ratio of the above-mentioned catalytically active component constituting the catalyst of the present invention to the above-mentioned carrier for supporting the catalytically active component is not particularly limited. However, when the catalytically active component is a noble metal, the catalytic activity and the durability of the catalyst are improved. 0.01% by mass or more, more preferably 0.05% by mass, based on the active ingredient
As described above, the content is more preferably 0.1% by mass or more, preferably 3% by mass or less, more preferably 2% by mass or less, and further preferably 1% by mass or less.

When the catalytically active component is other than a noble metal, the amount of the active component should be 0.1 from the viewpoint of catalytic activity and durability of the catalyst.
1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more,
Preferably 30% by mass or less, more preferably 20% by mass
Below, it is more desirable that it is below 10 mass%.

For example, when the catalyst is Pt—TiO ₂ ,
Is desirably 0.01% by mass or more and 3% by mass or less. When the catalyst is MnO ₂ —TiO ₂ , MnO
The O ₂ ratio is desirably 0.1% by mass or more and 30% by mass or less.

When a noble metal is used as the catalytically active component, it is desirable to calculate the content ratio of the noble metal as a metal. In addition, when the catalytically active component is other than a noble metal, it is desirable that the catalytically active component is generally a stable oxide and the content ratio of the oxide is calculated. 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, or 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 catalyst component of the present invention is not limited to the above examples, and may contain any combination of elements and compounds thereof. For example, the catalyst component may contain an alkali metal, an alkaline earth metal, or another transition metal. You may.

The carrier of the present invention has a main peak on the side of smaller pore diameter in the pore diameter of the carrier and the pore volume distribution with respect to the carrier, and has a minor peak smaller than the main peak on the side of larger pore diameter. In such a carrier, excellent mechanical strength, durability and activity can be obtained.

In the present invention, "a sub-peak smaller than the main peak" means that the height of the peak top of the sub-peak is lower than the height of the peak top of the main peak.
"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 the individual pores 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 is defined as the pore volume between pore diameters corresponding to 3% of the peak height, assuming that the peak top of the peak is 100% as shown in FIG. This is a cumulative value (in the pore diameter distribution curve in FIG. 4, the cumulative pore volume in the hatched portion). The pore volume of other peaks is
When the peak top of the peak height is 10% or more of the peak top of the main peak, it is a value obtained by accumulating pore volumes between pore diameters corresponding to 3% of the main peak height. When the peak height of the peak height is less than 10% of the peak top of the main peak, a base line is drawn between the peaks and between the absence of the peak, and a fine line between pore diameters higher than this base line is drawn. It is a value obtained by accumulating the pore volumes. 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, and most preferably 300 Å or less. It is desirable to have such a peak, and it is preferable that the pore diameter at the peak top be 80 Å or more from the viewpoint of obtaining excellent mechanical strength, durability and activity.

In the present invention, the subpeak may be located on the side where the pore diameter is larger than the main peak, and the range of the pore diameter where the subpeak exists is not particularly limited. It is recommended that the thickness be not less than Å, more preferably not less than 500 Å, preferably not more than 5 μm, more preferably not more than 3 μm. It is preferable from the viewpoint of the mechanical strength, durability, and catalytic activity of the catalyst if the peak top of the sub-peak exists within such a range, but if the sub-peak exceeds 5 μm, the mechanical strength of the catalyst may decrease. Is not preferred.

Although the number of peaks and the height of the peaks are not particularly limited, the carrier has only two peaks, that is, a main peak and a sub-peak, from the viewpoint of mechanical strength, durability and catalytic activity of the catalyst. 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 peak top value 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. In addition, if the log differential pore volume at the top of the peak other than the main peak is less than 1% of the main peak, it is not regarded as a peak.

Depending on the distribution state of the peaks, a so-called “shoulder type peak” having two peaks within the same peak may occur. However, as shown in FIG. 5, both peaks connecting a high peak and a 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 crystal structure or a crystal structure other than the anatase crystal structure. Preferred carriers are.

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.

In the present invention, the pore volume of the main peak relative to the total pore volume of the carrier is preferably 70% or more, more preferably 80% or more, and still more preferably 99% or less, more preferably 98% or less. The following is desirable from the viewpoint of improving the catalyst activity and the catalyst strength.

In the present invention, a mercury intrusion method is employed as a method for measuring the pore distribution of the pore diameter 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. Moreover, 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. As a result, the pore diameter and the corresponding pore volume and log differential pore volume can be obtained in the range of the pore diameter of 30 Å to 174 μm.
The value obtained by accumulating the pore volumes in the range of 174 μm 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 is 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 method 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 "particulate 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 made into 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 1.5 mm or more, more preferably 2.5 mm or more, and preferably 10 mm or more.
Or less, more preferably 6 mm or less. The thickness between adjacent through holes is preferably 0.1 mm or more, more preferably 0.5 mm or more, and preferably 3 mm or more.
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 90% or less, more preferably 85% 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. A honeycomb-shaped catalyst having a thickness between the through holes of less than 0.1 mm has an advantage that the weight of the catalyst can be reduced, but the mechanical strength of the catalyst may be reduced. 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 the reaction tower with the wastewater containing the suspended matter and the wet oxidation treatment is performed, the catalyst layer may be clogged by sedimentation 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 using the catalyst as described above, excellent catalytic activity and durability of the catalyst can be maintained for a long time, and high mechanical strength can be obtained. Further, when waste water is treated by the 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 wastewater 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.

In the present invention, the "wastewater" 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. 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 waste water 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 required to oxidize and / or decompose oxides in wastewater into 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 into the reaction tower as described above, or the wastewater may be heated after being supplied into the reaction tower. Good. The method for heating the wastewater is not particularly limited either, and a heater or a heat exchanger may be used, or a heater may be installed in the reaction tower to heat the wastewater. 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 for supplying the wastewater to the reaction tower, various modes 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 the long-term excellent oxidation is achieved. 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.

When a plurality of reaction towers are used, different catalysts may be used respectively, or a reaction tower filled with a catalyst and a reaction tower without 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 packing materials, 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 wastewater is oxidized and decomposed in the reaction tower. In the present invention, the term “oxidation and decomposition” means oxidative decomposition of acetic acid into water and 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 the form of low-molecular-weight compounds. 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 wastewater, 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 is performed. 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 may be used for the heater and the cooler, and these may 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 and alterations without departing from the spirit of the present invention will be described. Included in the scope.

[0080]

EXAMPLES Catalyst Preparation Example 1 A titania spherical shaped carrier having a main peak and a subpeak was used as a carrier used for catalyst preparation. The carrier has an average diameter of 4
mm, the average compressive strength (the average value of the load at which the carrier (catalyst) was loaded and the carrier was broken) was 3.5 kg / particle, the specific surface area was 42 m ² / g by the BET method, and the titania of the molded carrier was The crystal structure was of the anatase type. The main peak had a pick top at 230 angstroms, and the pore diameter range of the peak was 100 to 300 angstroms. Further, the total pore volume (total of pore volumes existing in the range of pore diameter 30 Å to 174 μm: 0.
The volume ratio of the main peak to about 34 ml / g) was about 80%. The minor peak has a peak top at 650 angstroms, and the pore size range of the peak is 400 to 30.
00 angstroms. The volume ratio of the auxiliary peak to the total pore volume was about 20%. Then, the carrier is impregnated with an aqueous solution of a catalytically active component (an aqueous solution of platinum nitrate is added to absorb the aqueous solution, dried at 120 ° C., and further calcined at 400 ° C. for 3 hours using a hydrogen-containing gas). Catalyst A-1) was obtained. The main components of the obtained catalyst (A-1) and the mass ratio thereof are as shown in Table 1. The pore volume, pore size distribution,
The specific surface area, average compressive strength, and titania crystal structure were almost the same as the carrier used.

Catalyst Preparation Examples 2 to 6 The method of using the carrier used in Catalyst Preparation Example 1 and impregnating the carrier with an aqueous solution of a catalytically active component was the same as in Catalyst Preparation Example 1 except that some of the raw materials were changed. Were used to prepare the catalysts (A-2 to A-6) shown in Table 1. -Catalyst Preparation Example 2 (A-2): An aqueous solution of palladium nitrate was used as a catalytically active component. -Catalyst preparation example 3 (A-3): An iridium chloride aqueous solution and a platinum nitrate aqueous solution were used as catalytic active components. -Catalyst preparation example 4 (A-4): Rhodium nitrate aqueous solution and platinum nitrate aqueous solution were used as catalytic active components. -Catalyst Preparation Example 5 (A-5): An aqueous solution of palladium nitrate and an aqueous solution of chloroauric acid were used as catalytically active components. -Catalyst Preparation Example 6 (A-6): A manganese nitrate aqueous solution was used as a catalytic active component, and a calcination treatment was performed in an air atmosphere instead of a hydrogen-containing gas.

The main components of the obtained catalysts (A-2 to A-6) and their mass ratios are as shown in Table 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 In the method of using the carrier used in Catalyst Preparation Example 1 and impregnating the carrier with an aqueous solution of a catalytically active component, except that an aqueous ruthenium nitrate solution was used as the catalytically active component, a catalyst preparation example 1 was used.
In the same manner as in Example 1, a catalyst (A-7) described in Table 1 was prepared. 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 and Comparative Preparation Example 3 As a carrier (pellet) used for preparing the catalyst, a titania molded 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, an average compressive strength of 3.8 kg / particle, and a specific surface area of 180 m ² / BET method.
g, and the titania crystal structure of the molded carrier was anatase type.

The main peak has a pick top at 100 Å, and the pore diameter range of the peak is 30 to 3
00 angstroms. The volume ratio of the main peak in the total pore volume (total pore volume in the range of pore diameter 30 Å to 174 μm: 0.38 ml / g) was about 95%. The minor peak had a peak top at 3000 angstroms, and the pore size range of the peak was 800 to 8000 angstroms.
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 the same catalytically active component as in Catalyst Preparation Example 1 (note that an aqueous platinum nitrate solution was used as the catalytically active component in Comparative Preparation Example 2, and an aqueous ruthenium nitrate solution was used as the catalytically active component in Comparative Preparation Example 3). Comparative Preparation Example 2 (A-8) and Comparative Preparation Example 3 (A-
9) was obtained. The main components of the obtained catalyst and the mass ratio thereof are as shown in Table 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 the carrier used.

[0086]

[Table 1]

Catalyst Preparation Examples 7 to 9 and Comparative Preparation Example 4 The carrier (pellet) used for preparing the catalyst was 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 had an average diameter of 5 mm, an average length of 6 mmL, an average compressive strength of 4.2 kg / particle, a specific surface area of 41 m ² / g by the BET method, and the titania crystal structure of the molded carrier was an anatase type. Note that the main peak has a pick top at 260 Å, and the pore size range of the peak is 60 to 10 μm.
00 angstroms. The volume ratio of the main peak in the total pore volume (total pore volume in the range of pore diameter 30 Å to 174 μm: 0.33 ml / g) was about 92%. The minor peak had a peak top at 3000 angstroms, and the pore size range of the peak was 1000 to 8000 angstroms. The volume ratio of the sub-peak to the total pore volume is about 6%
Met. Then, a method of impregnating the carrier with an aqueous solution of the same catalytically active component as in Catalyst Preparation Example 1 (in addition, an aqueous platinum nitrate solution was used as the catalytically active component in Catalyst Preparation Example 7 and Catalyst Preparation Example 8
An aqueous solution of palladium nitrate was used as the catalytically active component, an aqueous solution of manganese nitrate was used as the catalytically active component of Catalyst Preparation Example 9, and an aqueous solution of ruthenium nitrate was used as the catalytically active component of Comparative Preparation Example 4. ) According to Catalyst Preparation Example 7 (B-
1), Catalyst Preparation Example 8 (B-2), Catalyst Preparation Example 9 (B-
3), Comparative Preparation Example 4 (B-4) was obtained. The main components and the mass ratio of the obtained catalyst are as shown in Table 2.
The pore volume, pore size distribution, specific surface area,
The average compressive strength and the titania crystal structure were almost the same as the carrier used.

[0088]

[Table 2]

Catalyst Preparation Examples 10 to 12 and Comparative Preparation Example 5 The supports (pellets) used for preparing the catalysts were titanium oxide, iron oxide, and composite oxides of titanium and iron having a main peak and a subpeak. A molded carrier containing the product was used.
The carrier had an average diameter of 3 mm, an average length of 5 mmL, an average compressive strength of 4.3 g / particle, and a specific surface area of 48 m ² / BET method.
g, and the titania crystal structure of the molded carrier was anatase type. The main peak has a pick top at 180 angstroms, and the pore diameter range of the peak is 80 to
It was 600 angstroms. The volume ratio of the main peak to the total pore volume (total pore volume in the range of pore diameter 30 Å to 174 μm: 0.36 ml / g) was about 93%. Secondary peak is 4000
Angstrom had a peak top, and the pore diameter range of the peak was 1000 to 8000 Å. The volume ratio of the sub-peak to the total pore volume is about 5
%Met. Then, the carrier is impregnated with an aqueous solution of the same catalytically active component as in Catalyst Preparation Example 1 (catalyst preparation example 10).
An aqueous solution of platinum nitrate was used as the catalytically active component of Example 1, an aqueous solution of palladium nitrate was used as the catalytically active component of Catalyst Preparation Example 11, and an aqueous solution of manganese nitrate was used as the catalytically active component of Catalyst Preparation Example 12. An aqueous ruthenium nitrate solution was used. Catalyst Preparation Example 10
(C-1), Catalyst Preparation Example 11 (C-2), Catalyst Preparation Example 1
2 (C-3) and Comparative Preparation Example 5 (C-4) were obtained. The main components of the obtained catalyst and the mass ratio thereof are as shown in Table 3. The pore volume, pore size distribution, specific surface area, average compressive strength, and titania crystal structure of these catalysts were almost the same as the carrier used.

[0090]

[Table 3]

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, and after reaching 160 ° C., drainage treatment was performed for 1.5 hours. The processing pressure at this time was 4.1M.
Pa (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 is wastewater (COD (Cr) concentration: 22 g) discharged from an aliphatic carboxylic acid and aliphatic carboxylic acid ester production process containing formic acid, formaldehyde, acetic acid and the like.
/ Liter). Table 4 shows the treatment results of the obtained wastewater.
Shown in 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, but the average compressive strength was reduced to 2.1 kg / particle. .

Examples 2 to 6 and Comparative Example 1 The same wastewater treatment was performed in the same manner as in Example 1 except that the catalyst was changed to A-2 to A-7, respectively. Table 4 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 those of the catalyst (carrier) before the treatment, but the average compressive strength was 2.2 kg / particle (A).
-2), 2.3 kg / particle (A-3), 1.9 kg / particle (A-4), 2.4 kg / particle (A-5), 2.2 kg / particle
Grain (A-6) decreased to 2.3 kg / grain (A-7).

Comparative Example 2 The same wastewater treatment was performed in the same manner as in Example 1 except that the catalyst was changed to A-8. Table 4 shows the results. The pellet shape of the catalyst after the wastewater treatment collapsed (about 50% by mass).
There was also a lot of powder. The pore volume is 0.35 ml /
g, and the peak top of the main peak in the pore size distribution changed to 180 angstroms.
Incidentally, the average compressive strength of the catalyst, which had maintained the pellet shape, was reduced to 0.2 kg / particle, and the specific surface area was also 7% by the BET method.
It was reduced to 3 m ² / g. When the crystal structure of the treated catalyst was analyzed by X-ray diffraction (all of the crystal structures were analyzed by X-ray diffraction), the anatase-type crystal peak was sharp, and crystallization was not observed. Was progressing.

Comparative Example 3 The same wastewater treatment was performed in the same manner as in Example 1 except that the catalyst was changed to A-9. Table 4 shows the results. In addition, the pellet shape of the catalyst after wastewater treatment collapsed (about 60% by mass).
There was also a lot of powder. The pore volume is 0.34 ml /
g, and the peak top of the main peak in the pore size distribution changed to 190 angstroms.
Incidentally, the average compressive strength of the catalyst, which had maintained the pellet shape, was reduced to 0.2 kg / particle, and the specific surface area was also 7% by the BET method.
It was reduced to 1 m ² / g. The catalyst after the treatment had a sharp anatase-type crystal peak, and crystallization had progressed.

[0095]

[Table 4]

Example 7 Using the apparatus shown in FIG. 1, a treatment was performed for 100 hours under the following conditions. Reaction tower 1 (diameter 26 mm, length 3000)
0.8 liters of the catalyst (B-1) was charged inside the (cylindrical shape of mm). 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. COD of wastewater
(Cr) was 21 g / liter.

The waste water is supplied to the waste water supply pump 5 through the waste water supply line 6 and fed at a flow rate of 1.6 liter / h, and then heated to 160 ° C. by the heater 3 and supplied from the bottom of the reaction tower 1. did. Also after supplying air from an oxygen-containing gas supply line 8, is pressurized by a compressor 7, O ₂
/ COD (Cr) (oxygen content in supply gas / chemical oxygen demand of waste water) = 1.1 by controlling the flow rate of the oxygen-containing gas flow control valve 9 so as to satisfy 1.1. Mixed. In the reaction tower 1, the treatment was carried out in a gas-liquid upward parallel flow.
In the reaction tower 1, the temperature of the wastewater was kept at 160 ° C. by using the electric heater 2, and the oxidation and decomposition treatment was performed. The obtained processing liquid was sent to a gas-liquid separator 11 via a processing liquid line 10 and was subjected to gas-liquid separation. At this time, the liquid level was detected by the liquid level controller LC in the gas-liquid separator 11, 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,
Control was performed so as to maintain a pressure of 0.9 MPa (Gauge).

Table 5 shows the treatment results of the obtained wastewater. 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, but the average compressive strength was reduced to 2.5 kg / particle. I was

Examples 8 and 9 and Comparative Example 4 The same wastewater treatment was performed in the same manner as in Example 7 except that the catalysts were changed to B-2 to B-4, respectively. Table 5 shows the results. The catalyst after the wastewater treatment had substantially the same pore volume, pore diameter distribution, specific surface area, and titania crystal structure as the catalyst (carrier) before the treatment, but had an average compressive strength of 2.4 kg / particle (B).
-2), 2.3 kg / particle (B-3) and 2.5 kg / particle (B-4).

[0100]

[Table 5]

Example 10 Using the apparatus shown in FIG. 2, a treatment was performed for 100 hours under the following conditions. Reaction tower 31 (diameter 26 mm, length 300
0.8 liter of the catalyst (C-1) was filled in a (0 mm cylindrical) interior. The wastewater used for the treatment was a solvent wastewater containing a large amount of alcohols such as ethyl alcohol and propyl alcohol. COD (Cr) of wastewater is 3
It was 7 g / liter.

The waste water is supplied to a waste water supply pump 35 through a waste water supply line 36 and fed at a flow rate of 1.6 liter / h. Then, the waste water is heated to 250 ° C. by a heater 33 and supplied from the top of the reaction tower 31. did. After air is supplied from the oxygen-containing gas supply line 38 and the pressure is increased by the compressor 37, O ₂ / COD (Cr) (the amount of oxygen in the supply gas / the required amount of chemical oxygen in the wastewater) = 1.0. The flow rate was controlled by an oxygen-containing gas flow control valve 39 and mixed into the wastewater before the heater 33. In the reaction tower 31, the treatment was performed in a gas-liquid downward cocurrent. In the reaction tower 31, the electric heater 3
The waste water was kept at 250 ° C. by using No. 2 to carry out an oxidation / decomposition treatment. The obtained processing liquid is cooled to 80 ° C. in the cooler 34 through the processing liquid line 40, and then cooled by the pressure control valve 42.
And was decompressed. The pressure control valve 42 detects the pressure with a pressure controller PC and detects the pressure at 7.0 MPa (Gaug).
Control was performed to maintain the pressure of e). The discharged gas-liquid was sent to a gas-liquid separator 41, where the gas-liquid was separated.

The results of the treatment of the obtained waste water are shown in Table 6. 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, but the average compressive strength was reduced to 2.6 kg / particle. I was

Examples 11 and 12 and Comparative Example 5 Example 10 was repeated except that the catalyst was changed to C-2 to C-4, respectively.
The same wastewater treatment was performed in the same manner as described above. The results are shown in Table 6. In addition, the pore volume, pore size distribution,
The specific surface area and the titania crystal structure were almost the same as those of the catalyst (support) before the treatment, but the average compressive strength was 2.7 kg / particle (C-2), 2.5 kg / particle (C-3), and 2. 8kg /
It was reduced to grains (C-4).

[0105]

[Table 6]

[0106]

The catalyst of the present invention has excellent mechanical strength, durability and catalytic activity. Particularly, the catalyst of the present invention maintains excellent activity and durability for a long period of time in the wet oxidation treatment of wastewater. can do. 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 showing a peak top.

FIG. 4 is a schematic diagram showing the pore volume.

FIG. 5 is a schematic diagram showing a shoulder type peak.

[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

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01J 23/52 B01J 23/52 M 23/889 23/89 M 23/89 35/10 301G 35/10 301 C02F 1/74 101 C02F 1/74 101 B01J 23/84 311M (72) Inventor Kunisuke Miyazaki 992, Nishioki, Okihama-shi, Aboshi-ku, Himeji-shi, Hyogo F-term in Nippon Shokubai Co., Ltd. 4D050 AA13 AB07 AB14 AB16 BB01 BB02 BB09 BC01 BC02 BC06 BC07 BD02 BD06 BD08 4G069 AA03 AA12 BA01A BA02A BA04A BA04B BA05A BA05B BB02A BB02B BB04A BB04B BC31A BC32A BC33A BC33B BC43A BC44A BC58A BC60A BC62 BC66BABC BCBC BCA BC62B BCBC EC12X EC13X EC14X EC15X EC15Y EC20 EC22Y ED03

Claims (4)

[Claims] 1. A catalyst used for wet oxidation treatment of waste water, wherein the catalytically active component is manganese, iron, cobalt, nickel, cerium, chromium, praseodymium, copper, silver, gold, platinum, palladium, rhodium, and iridium. At least one element selected from the group consisting of or a compound containing one or more elements, wherein the carrier supporting the catalytically active component is titanium, zirconium, silicon, aluminum, tungsten, iron, manganese, cerium. And a compound containing at least one element selected from the group consisting of praseodymium and praseodymium, and a main peak on the side of the pore diameter of the carrier and the pore volume distribution with respect to the pore diameter being smaller. Characterized by having a sub-peak smaller than the main peak on the side with a larger pore diameter . 2. The catalyst for wastewater treatment according to claim 1, wherein a peak top of the main peak is at most 500 Å. 3. The specific surface area of the catalyst is 20 to 70 m ² /
The catalyst for wastewater treatment according to claim 1 or 2, wherein the catalyst is g. 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.