JP2894499B2 - Water treatment method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a water treatment catalyst used in an ozone reaction tank in water treatment such as deodorization treatment, sterilization treatment, and decolorization treatment using ozone.

<Conventional technology and its problems> Ozone treatment is widely used for oxidative decomposition and removal of harmful components, odor components, coloring components, and the like in water. It's being used. In particular, in recent years, the importance of trihalomethane has been increasing due to the problem of pollution, the problem of odor due to the deterioration of water intake quality in waterworks, and the necessity of advanced treatment by strengthening wastewater regulations. However, in the treatment using only ozone, the oxidation rate of these components is low, and the removal efficiency is low. On the other hand, a method in which ozone treatment and ultraviolet treatment are combined (JP-A-63-72396)
Although the removal efficiency is high, the processing speed is slow and the apparatus is complicated. There is also a catalyst (JP-A-57-500634) that enhances the removal efficiency of ozone by using it in combination with ozone treatment, but it is not sufficient in terms of treatment speed and durability.

On the other hand, dissolved ozone in water decomposes relatively quickly in an alkaline region, but its decomposition speed is slow in a neutral to acidic region, it takes time to decompose, and there is a problem of residual.

Accordingly, an object of the present invention is to provide a deodorizing treatment, a sterilizing treatment and / or
Or a decolorization treatment, that is, a water treatment catalyst that exhibits excellent treatment performance in performing at least one of these deodorization treatments, sterilization treatments and decolorization treatments, has ozone decomposition activity, and has stability for a long time. To provide.

<Means for Solving the Problems> The object of the present invention is to provide, as a catalyst A component, an oxide of at least one element selected from the group consisting of titanium, silicon, aluminum and zirconium, and a catalyst B component.
Contains at least one element selected from the group consisting of manganese, iron, cobalt, nickel, cerium, tungsten, copper, silver, gold, platinum, palladium, rhodium, ruthenium and iridium, which is insoluble or hardly soluble in water. This is achieved by a water treatment catalyst characterized by the following. Further, the present invention provides a water treatment used in deodorization treatment, sterilization treatment and / or decolorization treatment of water using ozone, wherein the catalyst is a fixed bed catalyst molded into a pellet, pipe or honeycomb shape. Catalyst.

The feature of the catalyst according to the present invention is that an oxide of at least one element selected from the group consisting of titanium, silicon, aluminum and zirconium as a catalyst A component and manganese, iron, cobalt, nickel, as a catalyst B component,
At least one element selected from the group consisting of cerium, tungsten, copper, silver, gold, platinum, palladium, rhodium, ruthenium and iridium contains a compound that is insoluble or hardly soluble in water.

That is, according to the study of the present inventors, the catalyst A component alone or the catalyst B component alone can obtain sufficient treatment activity and long-term stability in deodorization treatment, sterilization treatment, decolorization treatment, etc. of water using ozone. However, it has been found that when both the catalyst A component and the catalyst B component are contained, the treatment activity is increased, and the catalyst has little change over time. Ozone oxidation of compounds, viruses, bacteria, etc., which cause odor and coloring, which is the object of the above-mentioned treatment, proceeds efficiently on the catalyst of the present invention, and improves the treatment speed and the use efficiency of ozone. Further, since the catalyst of the present invention also has ozonolysis activity, residual ozonolysis can be performed simultaneously by appropriately setting the amount of the catalyst.

The proportion of each catalyst component in the catalyst of the present invention is such that the catalyst A component is 70 to 99.99% by weight as an oxide, preferably 80 to 99.95.
% By weight, wherein the catalyst B component is 0.01 to 30 as a metal or compound
Suitably, it is between 0.05 and 20% by weight. Preferably, among the elements constituting the component B, manganese, iron, cobalt, nickel, cerium, tungsten, copper and silver are used in an amount of a compound (for example, a compound insoluble or hardly soluble in water such as an oxide or a sulfide). ) As 0
~ 30% by weight, gold, platinum, palladium, rhodium,
Ruthenium and iridium are used in amounts of 0 to
10% by weight (however, the total amount of both is 0.01 to 30% by weight
It is. ). The total amount of the catalyst A component and the catalyst B component is 100% by weight. If the amount of the catalyst B component is less than the above range, the treatment activity is insufficient in deodorization treatment of water using ozone, sterilization treatment, decolorization treatment, and the like. If the amount exceeds, the cost of raw materials increases, and a corresponding effect cannot be expected. On the other hand, when the component of the catalyst A is within the above range, the moldability of the catalyst is improved and molding of various shapes is facilitated, the long-term stability of the catalyst is increased, and the activity is also positively affected. It is preferable from the viewpoint of catalytic activity that the catalyst A component and the catalyst B component are mutually dispersed within the above composition range.

Preferably, the catalyst A component is a composite oxide of at least two elements selected from the group consisting of titanium, silicon and zirconium. These composite oxides have strong solid acidity and a large BET surface area, and are preferable from the viewpoint of catalyst activity, catalyst moldability and strength stability.

The catalyst used in the present invention is preferably a fixed bed catalyst molded in the form of pellets, pipes or honeycombs, from the viewpoint of facilitating the handling of the catalyst and reducing the flow resistance of the treated water. In particular, when the treated water contains solids, the shape of the honeycomb is preferable because the possibility of clogging can be reduced.

The shape of this honeycomb has an equivalent diameter of the through hole of 2 to 20 m
m, the cell thickness is preferably in the range of 0.1 to 3 mm and the aperture ratio is in the range of 50 to 90%. In addition, the equivalent diameter is 2.5-15m
m, the cell thickness is more preferably in the range of 0.5 to 3 mm and the aperture ratio is in the range of 50 to 80%. When the equivalent diameter is less than 2 mm, the pressure loss is large, and particularly when water contains solids, clogging tends to occur. Equivalent diameter
If it exceeds 20 mm, the pressure loss is reduced and the possibility of clogging is reduced, but the catalytic activity is not sufficient. When the cell thickness is less than 0.1 mm, there is an advantage that the pressure loss becomes small and the catalyst can be reduced in weight, but it is not preferable because the mechanical strength of the catalyst decreases. When the cell thickness exceeds 3 mm, the mechanical strength is sufficient, but there is a disadvantage that the pressure loss increases. The aperture ratio is also 50 to 90% for the same reason as described above. Further, as the shape of the through hole, a square, a hexagon, a corrugated shape, or the like can be used. Since the honeycomb catalyst having the preferred shape conditions described above has sufficient mechanical strength and sufficient geometric surface area, it is excellent in durability, and can treat target water with low pressure loss and high flow rate. it can. In addition, even when solid content is contained in water, high activity can be maintained for a long time without clogging.

The method for preparing the catalyst of the present invention includes the following methods, but it is needless to say that the present invention is not limited to these methods. That is, the transition metal mentioned as the catalyst B component, the powder of the catalyst A component is added to an aqueous solution containing an active component such as a noble metal and mixed well, and the mixture is directly molded, dried at 50 to 120 ° C. and dried at 300 to 300 ° C. The catalyst can be calcined at 800 ° C., preferably 350 to 600 ° C., for 1 to 10 hours, preferably 2 to 6 hours. Alternatively, the mixture can be calcined to prepare a catalyst composition powder in advance, and the resulting mixture can be catalyzed by being supported on a suitable simple substance. Alternatively, the catalyst can be formed by molding, drying and calcining a powder of the component of the catalyst A to prepare a catalyst carrier in advance, carrying an aqueous solution of the metal salt of the component of the catalyst B by impregnation and calcining the catalyst.

When a composite oxide of at least two elements selected from the group consisting of titanium, silicon and zirconium is used as the catalyst A component, these composite oxide powders can be prepared as follows.

For example, as a method for preparing a binary composite oxide (hereinafter, referred to as TiO ₂ —SiO ₂ ) powder composed of titanium and silicon, the following method may be mentioned.

A method in which titanium tetrachloride is mixed with a silica sol, ammonia is added to form a precipitate, the precipitate is washed, dried and calcined at 300 to 650 ° C, preferably 350 to 600 ° C.

Add sodium silicate aqueous solution to titanium tetrachloride,
The mixture was reacted to form a precipitate, which was washed, dried and dried.
A method of baking at 650 ° C, preferably 350-600 ° C.

Ethyl silicate [(C ₂ H ₅ O) ₄ Si] is added to a water-alcohol solution of titanium tetrachloride to cause a hydrolysis reaction to form a precipitate, which is washed, dried, and then dried at 300 to 650 ° C., preferably 350 to 350 ° C. Baking at 600 ° C.

Ammonia is added to a water-alcohol solution of titanium oxychloride (TiOCl ₂ ) and ethyl silicate to form a precipitate, which is washed, dried and then dried at 300 to 650 ° C., preferably 350 to 6 ° C.
Baking at 00 ° C.

Among the above preferred methods, a particularly preferred method is preferred, and this method is specifically carried out as follows.
That is, the compound of the titanium source and the silicon source is TiO ₂
And so that the molar ratio of SiO ₂ is a predetermined amount, and in the form of an acidic aqueous solution or sol, titanium and silicon are converted to oxides at a concentration of 1 to 100 g /, preferably 10 to 80 g / keep. Under stirring, ammonia water was added dropwise as a neutralizing agent, and a coprecipitated compound consisting of titanium and silicon was formed at pH 5 to 10 for 10 minutes to 3 hours, separated, thoroughly washed, and then washed at 80 to 140 ° C. For 1 to 10 hours, and calcined at 300 to 650 ° C., preferably 300 to 600 ° C. for 1 to 10 hours, preferably 2 to 8 hours to obtain TiO ₂ —SiO ₂ powder.

The starting material can be selected from inorganic titanium compounds such as titanium chlorides and titanium sulfates and organic titanium compounds such as titanium oxalate and tetraisopropyl titanate as a titanium source, and a colloidal silicon source. It can be selected from silica, water glass, inorganic silicon compounds such as silicon tetrachloride, and organosilicon compounds such as tetraethylsilicate. Some of these raw materials have trace impurities and contaminants, but they do not pose a problem unless they significantly affect the physical properties of the obtained TiO ₂ —SiO ₂ .

In addition, a method for preparing a titanium and zirconium binary composite oxide (hereinafter, referred to as TiO ₂ —ZrO ₂ ) powder can be similarly performed.

And as a preferred method of adjusting the TiO ₂ -ZrO ₂ powder,
The following methods are mentioned.

A method in which titanium chloride is mixed with zirconium oxychloride, ammonia is added to form a precipitate, and the precipitate is washed, dried and calcined at 300 to 650 ° C, preferably 350 to 600 ° C.

Zirconium nitrate is added to titanium tetrachloride and subjected to a thermal hydrolysis reaction to form a precipitate, which is washed and dried.
A method of firing at 300 to 650 ° C, preferably 350 to 600 ° C.

Examples of the starting material of the catalyst B component used together with the catalyst A component include oxides, hydroxides, inorganic acid salts, and organic acid salts, such as ammonium salts, oxalates, and nitrates.
It is appropriately selected from sulfates or halides.

The catalyst of the present invention adsorbs odors, compounds that cause coloration, viruses, bacteria, and the like onto the catalyst, and makes ozone oxidation proceed efficiently on the catalyst. The processing reaction rate increases as the temperature increases, but the ozone decomposition rate also increases at the same time. Therefore, the processing temperature is preferably in the range of 0 to 60 ° C. The amount of water to be treated varies depending on the target treatment rate and conditions, but is usually used at a flow rate of 1 to 1000 / h per catalyst. The pressure condition is not particularly limited, but can be sufficiently used at normal pressure. The supply of ozone to the catalytic reaction layer includes a method of supplying ozone in a state where ozone is dissolved in advance, and a method of flowing an ozone-containing gas together with water to be treated through the catalytic reaction layer.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to only these Examples.

Example 1 A binary composite oxide of titanium and zirconium was prepared by the method described below. An aqueous solution of titanyl sulfate in sulfuric acid having the following composition was used as a titanium source.

TiOSO ₄ (TiO ₂ terms) 250 g / total H ₂ SO ₄ 1100g / separate the water 50 of zirconium oxychloride [ZrOCl ₂ · 8H
_[2 O] 1.93 Kg was dissolved and mixed well while being added to an aqueous sulfuric acid solution 7.7 of titanyl sulfate having the above composition. This is about 3
While maintaining the temperature at 0 ° C. and stirring well, aqueous ammonia was gradually added dropwise until the pH reached 7, thereby forming a coprecipitated gel. Furthermore, it was left as it was and allowed to stand for 15 hours. Then
After filtration and washing with water, drying was performed at 200 ° C. for 10 hours, and calcination was performed at 500 ° C. for 5 hours in an air atmosphere. The composition of the obtained powder is TiO ₂ : Z
rO ₂ = 4: 1 (molar ratio), and the BET surface area was 150 m ² / g.

850 ml of water, 1.5 kg of the above powder and 75 g of starch were added and mixed, and kneaded well with a kneader. This was extruded into a honeycomb type having a hole diameter (equivalent diameter of through hole) of 3 mm, a cell thickness of 0.6 mm, and an opening ratio of 69%, dried at 120 ° C. for 6 hours, and then heated at 450 ° C.
For 6 hours.

The molded body thus obtained was impregnated with a cerous nitrate aqueous solution, dried at 120 ° C. for 6 hours, and calcined at 400 ° C. for 3 hours to obtain a catalyst containing 5% by weight of CeO ₂ .

Example 2 Titanium and silicon having a composition of TiO ₂ : SiO ₂ = 4: 1 (molar ratio) and a BET surface area of 170 m ² / g using colloidal silica instead of zirconium oxychloride according to Example 1. Was obtained as a binary composite oxide powder.

This powder was formed into pellets having a diameter of 5 mm according to the method of Example 1, and a catalyst containing 0.4% by weight of rhodium was obtained using an aqueous rhodium chloride solution.

Example 3 0.69 kg of manganese nitrate [Mn (NO ₃ ) ₂ .6H ₂ O] was added to water 2.1
And added to 5 kg of commercially available titanium oxide powder.
According to the method described in the above, extrusion molding was performed into a honeycomb mold having a hole diameter (equivalent diameter of a through hole) of 6 mm, a cell thickness of 1.08 mm, and an opening ratio of 72%. The composition of the obtained catalyst was MnO ₂ (4% by weight) -TiO ₂ (96% by weight).

Example 4 A commercially available γ-alumina carrier having a diameter of 4 mm was impregnated with an aqueous rhodium chloride solution, dried and calcined to obtain Rh (1% by weight) -Al ₂ O _3.
(99% by weight) of the catalyst was obtained.

Examples 5 to 13 Catalysts having the compositions and shapes shown in Table 1 were obtained according to Examples 1 to 3.

Here, the binary composite oxide of titanium and silicon is referred to as TS
And a binary composite oxide of titanium and zirconium is denoted as TZ. The molar ratio of the two elements of the binary composite oxide was expressed as [mol% of titanium: mol% of other elements].

Example 14 A reaction tube was charged with 200 ml of the catalysts of Examples 1 to 13, and sewage secondary treated water was flowed at a flow rate of 4 / hr, and a gas containing ozone was flown at an ozone flow rate of 0.5 g / hr. The reaction was performed at room temperature. As a comparative example, the case where the catalyst was not filled in the reaction tube was also performed. The chromaticity of water, odor, number of coliforms, and ozone content at each reactor inlet and outlet were measured. As the odor intensity, a 6-step odor intensity display method was used. Table 2 shows the processing results.

Example 15 After the reaction was continued under the conditions of Example 14 for 1000 hours, the catalyst was extracted. A crushing strength test of the catalyst was performed to determine the strength ratio between the catalyst before the reaction and the catalyst after the reaction. Table 3 shows the results.

Example 16 A reaction tube was filled with 300 ml of the catalysts of Examples 1 and 3, and water containing 500 mg / SS (suspended matter) was flowed at a flow rate of 10 / h, and a gas containing ozone was flown at an ozone flow rate of 0.7 g. / h, and reacted at room temperature. Even after 1000 hours from the start of the reaction, the catalyst did not block.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01J 23/70 B01J 23/70 Z (72) Inventor Kunio Sano 992 Koishihama, Nishioki, Aboshi-ku, Himeji-shi, Hyogo 1 Nippon Shokubai Chemical Co., Ltd. (72) Inventor Akira Inoue 992, Nishioki, Okihama-shi, Abashiri-ku, Himeji City, Hyogo Prefecture References JP-A-63-158189 (JP, A) JP-A-51-34560 (JP, A)

Claims (4)

(57) [Claims] An oxide of at least one element selected from the group consisting of titanium, silicon, aluminum and zirconium as a catalyst A component and manganese, iron, cobalt, nickel, cerium, tungsten, copper, as a catalyst B component. A temperature of 0 to 60 ° C. in the presence of a catalyst containing a water-insoluble or sparingly soluble compound of at least one element selected from the group consisting of silver, gold, platinum, palladium, rhodium, ruthenium and iridium; A water treatment method comprising performing deodorization treatment, sterilization treatment and / or decolorization treatment of water using ozone under normal pressure. 2. The catalyst A component has an oxide content of 70 to 99.99% by weight, and the catalyst B component has a metal or compound content of 0.01 to 99.99% by weight.
The method according to claim 1, wherein the amount is 30% by weight. 3. The process according to claim 1, wherein the catalyst is a fixed bed catalyst formed in the form of pellets, pipes or honeycombs. 4. The method according to claim 1, wherein the catalyst A component is a composite oxide of at least two elements selected from the group consisting of titanium, silicon and zirconium.