JPH01218634A - Water-resistant catalyst support, its manufacturing method, water-treatable catalyst deposited on said support and water treating method using said catalyst - Google Patents

Abstract

PURPOSE:To permit a catalyst support to be used stably for a long period of time under severe water treating conditions, by forming a water-resistant and -treatable catalyst support containing the multiple oxide of titanium and zirconium having a crystal of ZrTiO4. CONSTITUTION:A titanium compound and a zirconium compound are heated at a temperature of 600-1000 deg.C, preferably 660-900 deg.C to form a water-resistant catalyst support containing a multiple oxide of titanium and zirconium having a bond structure of ZrTiO4. At least one metallic, water-insoluble or indissoluble compound selected as a catalytically active component from the group consisting of Mn, Fe, Co, Ni, Ce, W, Cu, Ag, Au, Pt, Pd, Rh, Ru and Ir is deposited on this catalyst support to form a water-treatable catalyst. It is preferable for said catalyst support to have the composition of TiO2 of 20-90 molar percent and ZrO2 of to 10-80 molar percent.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a water-resistant carrier, a method for producing the same, a water treatment catalyst containing the carrier, and a water treatment method using the catalyst. Specifically, the present invention relates to a carrier having stable water resistance even in acidic/alkaline water or hot water, a method for producing the same, a water treatment catalyst containing the carrier, and a water treatment catalyst containing the catalyst. Regarding processing method.

<Prior Art> Carriers and catalysts for water treatment are widely used in chemical treatment, biological treatment, etc. of water, and are utilized in clean water treatment, waste water treatment, etc. Materials for these carriers include plastics, activated carbon, ceramics, and the like. Depending on the water treatment conditions, some methods are used under harsh conditions, and in particular, the conditions for wet oxidation, which oxidizes and decomposes wastewater containing chemical oxygen demand substances (hereinafter referred to as CO [) components) under high temperature and high pressure, are In order to improve the durability of the carrier used for this purpose, a method using a titania carrier has been proposed.

<Problems to be Solved by the Invention> Conventional carriers and catalysts for water treatment have a problem in that they cannot withstand long-term use under severe conditions. For example, plastic items used in high-temperature hot water may melt, and ceramic items may cause components to be eluted. Furthermore, when used in low pl-1 wastewater containing mineral acids and organic acids, deterioration and elution of components may be accelerated. In particular, supports and catalysts used in wet oxidation methods are required to have high durability in hot water and stability under a wide range of pH conditions, but there have been no supports that fully satisfy these conditions.

According to studies conducted by the present inventors, it has been found that, for example, a wet oxidation catalyst using a titania carrier is initially water resistant, but the catalyst strength decreases over a long period of time.

Therefore, in view of the various drawbacks mentioned above, the object of the present invention is to
The object of the present invention is to provide a carrier and a catalyst that have strength stability for a longer period of time than these conventional products in water treatment. Another object of the present invention is to provide a method for producing the carrier and a method for using the catalyst.

<Means for Solving the Problems> According to the present invention, (1) a water-resistant carrier characterized by containing a composite oxide of titanium and zirconium having a crystal structure of ZrTiO4;

(2) A method for producing a water-resistant carrier containing a composite oxide of titanium and zirconium having a crystal structure of ZrTiO4, which comprises heating a mixture of a titanium compound and a zirconium compound in a temperature range of 600 to 1000°C.

(3) Manganese, iron, cobalt, nickel, cerium, tungsten, copper, silver, gold, platinum as catalytically active components on a carrier containing a composite oxide of titanium and zirconium having a crystal structure of ZrTiC)4. A water treatment catalyst comprising at least one metal selected from the group consisting of , palladium, rhodium, ruthenium and iridium, or a water-insoluble or sparingly soluble compound thereof.

(8) Manganese, iron, cobalt, nickel, cerium, tungsten, copper, silver, and gold as catalytically active components are added to a carrier containing a composite oxide of titanium and zirconium having a crystal structure of Z rT i O4. ,platinum,
Using a water treatment catalyst made of at least one metal selected from the group consisting of palladium, rhodium, ruthenium, and iridium, or a water-insoluble or sparingly soluble compound supported thereon, wastewater is heated in a temperature range of 100 to 370°C. and 1.0 to 1.5 times the theoretical amount necessary to decompose organic and inorganic substances in the wastewater into nitrogen, carbon dioxide, and water under a pressure that maintains the liquid phase of the wastewater. A water treatment method characterized in that the wastewater is wet oxidized under the supply of a gas containing a certain amount of oxygen.

achieved by

A feature of the carrier according to the present invention is that it contains a composite oxide of titanium and zirconium having a crystal structure of ZrTiO4.

In general, binary composite oxides consisting of titanium and zirconium are described, for example, by Kozo Tabe, Catalysts, Vol. 17, No. 3.
．． 72 (1975), it is known as a solid acid and exhibits remarkable acidity that is not found in the constituent oxides alone.

In other words, the composite oxide is not simply a mixture of titanium oxide and zirconium oxide, but it can be recognized that titanium and zirconium form a so-called binary composite oxide, resulting in its unique physical properties. It is. When fired at low temperatures, this composite oxide
As a result of analysis by line diffraction, it has an amorphous or almost amorphous microstructure.

On the other hand, the present inventors prepared a mixture of a titanium compound and a zirconium compound at a temperature of 600 to io'oo°C, preferably 66°C.
ZrTi by heating in the temperature range of 0~900℃
It has been found that a composite oxide of titanium and zirconium having the crystal structure C) 4 can be produced and is excellent as a component of a water-resistant carrier.

A method for producing a carrier containing the crystal structure of ZrT104 is a method in which a close compound of titanium and zirconia is formed in advance and then heated at a temperature range of 600 to 1000°C, preferably 660 to 900°C. is even more preferable. When the heating temperature is less than 600℃, Zr
It cannot have the crystal structure of TiO4. Also, i oo
At temperatures above 0° C., the specific surface area of the oxide decreases significantly, resulting in a decrease in carrier moldability and carrier strength.

Note that the substance ZrTiO4 can be identified by X-ray diffraction. (HcClune, W, F, etc.

'1982 Powder Diffraction
File, InorganicPhases, Alpha
abetical Index”, JCPDS
Tinter-national Center for
Diffraction Data.

(see Penn 5ylvania, 1982).

In the water-resistant carrier of the present invention, ZrTiO is used in terms of hot water resistance.
The proportion of the composite oxide of titanium and -9=zirconium in the carrier having a crystal structure of 4 is 10.
It is preferably at least 20% by weight, more preferably at least 20% by weight.

The composition of this carrier component is 2 as TiO2.
A range of 0 to 90 mol % and 10 to 80 mol % of ZrC)+ gives preferable results in terms of durability, carrier moldability, and strength. Furthermore, 30 to 80 mol% as T i 02 and ZrO2
A more preferable result is obtained when the content is in the range of 20 to 70 mol%.

Further, a composite oxide of titanium and zirconium having a crystal structure such as ZrTiO4 and an oxide of a rare earth element such as lanthanum or neodymium, titania, zirconia, etc. can be used in combination to form a carrier.

The present inventors have found that when using a carrier component containing the above-mentioned composite oxide, the durability and moldability are significantly superior when molded into pellets, spheres, honeycomb shapes, etc.
It has been found that the carrier maintains its shape and strength over a long period of time even when used in water treatment which requires severe conditions such as high temperature, high pressure, and low pH of 1 to 1. Moreover, it has been found that a catalyst in which a catalyst component is supported on this carrier is not only durable but also excellent in water treatment efficiency.

That is, according to the studies of the present inventors, excellent performance cannot be obtained by using titanium and zirconium oxides alone or simply as a mixture, and even if they can be formed into a honeycomb shape, for example, they cannot withstand long-term use. However, it was found that excellent durability and moldability can only be achieved by incorporating these elements into a form containing the above-mentioned composite oxide. In particular, the carrier containing the above-mentioned composite oxide was found to have even better durability in terms of carrier strength in terms of hot water resistance.

The amount of the catalytically active component supported in the water treatment catalyst of the present invention is suitably in the range of 0.05 to 25% by weight in the form of metal or compound. Preferably, the amounts of manganese, iron, cobalt, nickel, cerium, tungsten, copper and silver used as compounds (e.g. oxides, chlorides, sulfides, etc.) are O~25-11 = % by weight, platinum, The amount of gold, palladium, rhodium, ruthenium and iridium used is 0 to 10 as metals.
% by weight (however, the total amount of both is 0.05 to 25
Weight%. ). More preferably, the catalytically active component is from 0.1 to 15% by weight in metal or compound form. Preferably, the amounts of manganese, iron, cobalt, nickel, cerium, tungsten, copper and silver used as compounds are 0 to 15% by weight, and the amounts of platinum, gold, palladium, rhodium, ruthenium and iridium used as metals are 0 to 15% by weight. ~5% by weight (however, the total amount of both is 0.1 to 15% by weight).

If the catalytic active component is outside the above range, the water treatment activity will be insufficient, and in the case of noble metals such as platinum, palladium and rhodium, the raw material cost will be high and a correspondingly sufficient effect cannot be produced.

The carrier and catalyst of the present invention preferably have the composition specified above, and are in the form of pellets,
Various shapes such as a spherical shape, a ring shape, a saddle shape, a powder shape, a crushed type, and an integral structure such as a honeycomb can be adopted. Preferably, it is a honeycomb structure, and particularly preferably, the structure has a shape in which the equivalent diameter of the through hole is in the range of 2 to 20 m, the cell wall thickness is in the range of 0.5 to 3 mm, and the aperture ratio is in the range of 50 to 80%. It has the following. In a honeycomb structure, if the pore diameter (through-hole equivalent diameter) is increased, the flow resistance decreases proportionally and clogging by solid matter can be prevented, but at the same time, the geometric surface area of the structure also decreases, and In order to achieve the processing efficiency of 1, it is necessary to increase the amount of the structure by increasing the pore diameter.Therefore, the pore diameter is limited due to the relationship with processing efficiency and processing performance.

In the honeycomb structure described above, the equivalent diameter of the through hole is 2
-20m, preferably 4-12mm. If the equivalent diameter is less than 2 mm, the pressure loss will be large, and especially if the water to be treated contains solids, clogging will easily occur, making it difficult to use it for a long time. If the equivalent diameter exceeds 20 mm, the pressure loss will be small and the possibility of clogging will be reduced, but the processing activity will not be sufficient.

Cell thickness is 0.5-3mm, preferably 0.5-2mm
is within the range of When the cell wall thickness is less than 0.5 s, there is an advantage that the pressure loss is small and the weight of the structure can be reduced, but it is not preferable because the mechanical strength is reduced.

When the cell wall thickness exceeds 3#, mechanical strength is sufficient, but there is a drawback that pressure loss becomes large.

The aperture ratio is also 50 to 80% for the same reason as above.

Considering the above circumstances, a particularly preferable honeycomb structure used in the present invention has an equivalent diameter of through holes of 2 to 20#, a cell wall thickness of 0.5 to 3 gates, and an aperture ratio of 5.
It ranges from 0 to 80%. A honeycomb structure having these conditions has a reaction temperature of 100 to 370°C,
It has sufficient mechanical strength even under severe reaction conditions of high temperature and pressure, where the reaction pressure is higher than the pressure that maintains the liquid phase of the water to be treated, and the geometric surface area of the structure is also sufficient. Because of this, it has excellent durability and can perform water treatment at high linear speeds with low pressure loss. Moreover, even when solid content is contained in the water to be treated, high activity can be maintained for a long period of time without clogging.

As for the shape of the through-hole, any shape such as square, hexagonal, wave-like, etc. can be adopted as long as its equivalent diameter is within the above-mentioned range.

In order to prepare a carrier containing a composite oxide of titanium and zirconium having a crystal structure called ZrTiO4 of the present invention, titanium chlorides, titanium sulfate, titanium sulfate,
It can be selected from inorganic titanium compounds such as titanic acids and organic titanium compounds such as titanium oxalate and tetraisopropyl titanate. Zirconium sources include inorganic zirconium compounds such as zirconium oxychloride, zirconium nitrate, and zirconium sulfate, and oxalic acid. It can be selected from organic zirconium compounds such as zirconium.

Preferred preparation methods include the following methods.

■ Titanium tetrachloride is mixed with zirconium oxychloride, ammonia is added to form a precipitate, and this precipitate is washed and dried at 600 to 1000°C, preferably 660°C.
A method of heating at ~900°C.

■ Zirconyl nitrate is added to titanium tetrachloride, a thermal hydrolysis reaction is performed to form a precipitate, which is washed, dried, and then
A method of heating at 00 to 1000°C, preferably 660 to 900°C.

■ Add zirconyl nitrate to titanic acid, heat it to thermally decompose it, and then heat it to 600-1000°C, preferably 66°C.
A method of heating at 0 to 900°C.

Among the above preferred methods, method (2) is particularly preferred, and this method is specifically carried out as follows. That is, the above-mentioned titanium source and zirconium source compounds are taken so that the molar ratio of T i 02 and 7rO2 is a predetermined amount, and titanium and zirconium are converted into oxides as S marks of 1 to 100 g/l in an acidic aqueous solution state. 10-1
Keep at 00℃. Aqueous ammonia was added dropwise as a neutralizing agent into the solution while stirring, and the pH was kept at pH 2-10 for 10 minutes to 3 hours to form a coprecipitated compound consisting of titanium and zirconium. 1 in °C
Dry for ~10 hours at 600-1000°C, preferably 6
This is a method of heating at 60 to 900°C for 0.5 to 10 hours.

A finished catalyst can be obtained by the method shown below using a carrier containing a composite oxide of titanium and zirconium having a crystal structure called ZrTiO4 (hereinafter referred to as T i 02-ZrO2) prepared by the above method. - For example, T i 02-ZrO2 powder is added together with a molding aid, mixed and kneaded while adding an appropriate amount of water, and molded into a sphere, pellet, plate, honeycomb, etc. using an extrusion molding machine.

After drying the molded product at 50 to 120°C, it is calcined at 300 to 800°C, preferably 350 to 600°C, for 1 to 10 hours, preferably 2 to 6 hours, to obtain a catalyst.

Starting materials for catalyst active components include oxides, hydroxides,
Examples include inorganic oxide salts and organic acid salts, such as ammonium salts, oxalates, nitrates, sulfates, halides, and the like.

When Ti02-ZrO2 is catalyzed by adding manganese, iron, nickel, cobalt, tungsten, cerium, copper, silver, gold, platinum, palladium, rhodium, ruthenium and/or iridium, an aqueous solution of the above metal salt is
i 02-Z ro+ It can be made into a catalyst by impregnating and supporting the molded body, followed by drying and firing.

Alternatively, a method may be adopted in which an aqueous solution of the metal salt described above is added to the T i 02-Z ro2 powder together with a molding aid, and the mixture is kneaded and molded.

The water treatment carrier and catalyst of the present invention can treat target components contained in water by bringing them into contact with clean water, sewage, waste water, etc. Some specific treatment examples include heavy metal adsorption in hot water, ozone removal in water, filtration of strongly alkaline and strongly acidic water, oxidation treatment in hot water, and sterilization of bacteria and microorganisms in water. .

In particular, the water treatment method provided by the present invention can be applied to activated sludge-treated supernatant water or settled activated sludge, fermentation wastewater, wastewater from an organic compound polymerization process, cyanide-containing wastewater, phenol-containing wastewater, oil-containing wastewater, and other wastewater. It is excellent for wet oxidation treatment of chemical factory wastewater, general industrial wastewater from food factories, etc., wastewater containing oxidizable organic or inorganic substances such as human waste, sewage, and sewage sludge. In addition, the method of contact with wastewater may be column packing method, batch method, etc., but if a honeycomb type catalyst is used, even wastewater containing 0.1 g/1 or more of solids can be treated stably over a long period of time. be able to.

The reaction conditions applicable to the present invention are that the reaction temperature is 370°C or lower, usually 100 to 370°C, more preferably 200 to 30°C.
It is 0°C. The pressure of the reaction system is sufficient to maintain the liquid phase of the wastewater in the reaction tower, that is, 1 to about 200 KFI/c.
3. The pressure should be rn. The molecular oxygen-containing gas to be fed is in the theoretical M equipment required for oxidative decomposition.
Use 5 times the amount. The amount of catalyst used is about 5 to 99% of the space volume of the reaction column. The waste water is boiled over a catalyst bed at a predetermined temperature for a boiling time of 6 to 120 minutes, preferably 12 to 60 minutes.
It is oxidized by flowing with molecular oxygen-containing gas in minutes.

As the molecular oxygen-containing gas, air, a mixed gas of oxygen and air, or a gas commonly called oxygen-enriched air is used. l)H in the reaction system can be employed either on the acidic side or on the alkaline side.

The present invention will be explained in more detail below using Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 A sulfuric acid aqueous solution of titanyl sulfate having the following composition as a titanium source and I was used.

Ti OS 04 (Ti02 conversion >2'
50 g/1 total 1-+2304 11
00Q/1 Zirconium oxychloride (Zr
Dissolve 1.99Kg of OCl2 .8H20) into an aqueous sulfuric acid solution of titanyl sulfate with the above composition. was added and mixed well. While maintaining the temperature at 30°C and stirring well, ammonia water was gradually added dropwise to p! =1
The mixture was added until the number reached 7, and the mixture was further left to stand for 15 hours.

The T i 02-7 r02 gel thus obtained was filtered, washed with water, and then dried at 200'C for 10 hours. The mixture was then heated at 700° C. for 3 hours in an air atmosphere. The composition of the obtained powder was TiO2:Zr02=6:/1 (molar ratio), the BET surface area was 60'IrL/g, and X-ray diffraction analysis revealed that it had a crystal structure of ZrT104. The powder thus obtained was hereinafter referred to as P-1, and a catalyst was prepared using this powder by the method described below.

To 900 d of water, 1,500 g of the above powder and 75 g of starch were added, mixed, and kneaded well in a kneader.

After kneading with further addition of an appropriate amount of water, extrusion molding into a honeycomb mold with a pore size (equivalent diameter of through holes > 4 m and porosity of 64%), drying at 120°C for 6 hours, and drying at 450°C for 6 hours.
The thus obtained molded body, which had been fired for an hour, was impregnated in an aqueous chloroplatinic acid solution, then dried at 120°C for 6 hours, and then heated at 400°C for 3 hours.
Baked for an hour.

= 21- The composition of the finished catalyst obtained is P-1:Pt=98 in weight ratio
．． 2: There was 0.8.

Example 2 Water 41 Zirconyl dinitrate (ZrO(NO3) 2-2
820) Dissolve 1.29Kg and 0.9Kg titanic acid
(TiO2 equivalent) was added to this and 80' was added while mixing well.
It was dried at C. Then, it was fired at 750° C. for 3 hours in an air atmosphere. The composition of the obtained powder had a molar ratio of TiO2 and 7rO2 of 7:3. In addition, the BET surface area of this powder is 30TrL2/g, and as a result of X-ray diffraction analysis, Zr
It had a crystal structure of Ti○4. The powder obtained here is hereinafter referred to as P-2.

450 d of water, 1000 Q of the above powder, and 30 G of starch were added, mixed, and kneaded well with a kneader. 5m of this
After extrusion molding into cylindrical pellets with a diameter of 45 mm and drying,
It was baked at 0°C for 6 hours.

Next, the method described in Example 1 was followed except that a palladium nitrate aqueous solution was used instead of the chloroplatinic acid aqueous solution.
-2: A catalyst with Pd = 98.5: 1.5 was obtained.

Example 3 Using each of the catalysts obtained in Examples 1 and 2, wastewater was treated by a wet oxidation method in the following manner. A stainless steel reaction tube was filled with catalyst, and 500% of preheated mixed waste water and air with an oxygen concentration of 21% were introduced from the bottom of the reaction tube.
After continuous introduction for 0 hours, C
The OD (Cr) was measured and the removal rate after 5000 hours of reaction was determined.

The strength of the catalyst was also measured at the initial stage and after 5000 hours of reaction to determine the catalyst strength ratio. The properties of the wastewater used for treatment were COD (Cr) 40g/j! , [)H3. The reaction conditions were a reaction humidity of 1230°C and a reaction pressure of 60 kg.
/ cm2, and the space velocity of the wastewater is 1.58 r−1
(based on the empty column) and an air space velocity of 2401"r" (based on the empty column, under standard conditions).The results obtained are shown in Table 1.

Chapter 1 Table

Claims (8)

[Claims] (1) A water-resistant carrier characterized by containing a composite oxide of titanium and zirconium having a crystal structure of ZrTiO_4. (2) 20 to 90 mol% as titania (TiO_2)
and 10 to 80 mol% of zirconia (ZrO_2).
Carrier described in Section. (3) A method for producing a water-resistant carrier containing a composite oxide of titanium and zirconium having a crystal structure of ZrTiO_4, which comprises heating a mixture of a titanium compound and a zirconium compound at a temperature range of 600 to 1000°C. (4) The method according to claim 3, wherein the heating temperature is in the range of 660 to 900°C. (5) Manganese, iron, cobalt, nickel, cerium, tungsten, copper, silver, gold, platinum, palladium as catalytically active components in a carrier containing a composite oxide of titanium and zirconium having a crystal structure called ZrTiO_4. 1. A water treatment catalyst comprising at least one metal selected from the group consisting of rhodium, ruthenium and iridium, or a water-insoluble or sparingly soluble compound thereof. (6) The composition of the carrier is 20 to 90 mol% as TiO_2
The catalyst according to claim 5, characterized in that the amount of ZrO_2 is 10 to 80 mol%. (7) The catalyst according to claim 5, wherein the supported amount of the catalytically active component is in the range of 0.05 to 25% by weight. (8) Manganese, iron, cobalt, nickel, cerium, tungsten, copper, silver, gold, platinum, palladium as catalytically active components in a carrier containing a composite oxide of titanium and zirconium having a crystal structure called ZrTiO_4. Using a water treatment catalyst comprising at least one metal selected from the group consisting of rhodium, ruthenium, and iridium, or a water-insoluble or sparingly soluble compound thereof, wastewater is treated at a humidity range of 100 to 370°C. , and 1.0 to 1.5 times the theoretical amount necessary to decompose organic and inorganic substances in the wastewater into nitrogen, carbon dioxide, and water under a pressure that maintains the liquid phase of the wastewater. 1. A water treatment method comprising wet oxidizing the wastewater while supplying a gas containing oxygen.