JP2013013868A - Hydrogen peroxide decomposition catalyst and method for manufacturing the same, and disinfection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen peroxide decomposition catalyst capable of sufficiently disinfecting an object to be treated by achieving coexistence with the object to be treated in hydrogen peroxide solution and capable of significantly reducing the residual concentration of hydrogen peroxide after a predetermined time elapses.SOLUTION: The hydrogen peroxide decomposition catalyst, which decomposes hydrogen peroxide in a liquid phase into water and oxygen and includes a carrier formed from an inorganic oxide material with air cavities, and an active metal containing at least one type of element selected from the group consisting of Pt, Pd, Ir, Ru, Rh and Os supported on the carrier. The thickness of a layer supported with the active metal is 0.01-0.25 mm in the vicinity to the surface of the carrier.

Description

The present invention relates to a catalyst for decomposing hydrogen peroxide (H ₂ O ₂ ). Hydrogen peroxide is not only used as an oxidizing reagent in the chemical industry, but for example, hydrogen peroxide is used for sterilization in the fields of medicine, food, and drinking water.

After the use of hydrogen peroxide or a solution thereof, it is desired that the hydrogen peroxide is decomposed into harmless water and oxygen, and the residual amount is sufficiently low. Conventionally, a catalyst carrying Pt or Pd is used for the decomposition treatment of hydrogen peroxide, and it is known that the following reaction is promoted in the presence of a platinum group metal (for example, Patent Document 1). , 2).
Hydrogen peroxide decomposition reaction: 2H ₂ O ₂ → 2H ₂ O + O ₂

  In addition, in order to maintain the activity of the hydrogen peroxide decomposition catalyst over a long period of time, a method of using a substance having an oxygen-hydrogen bonding ability as the catalyst and supplying hydrogen gas to the catalyst when the activity of the catalyst decreases is known. (For example, refer to Patent Document 3). In Patent Document 3, the decrease in the activity of the hydrogen peroxide decomposition catalyst is because oxygen generated by the decomposition of hydrogen peroxide adheres to the surface of the catalyst and covers the surface of the catalyst. It is disclosed that by supplying gas, oxygen reacts with hydrogen and is removed from the catalyst surface to restore the catalytic activity.

  By the way, the hydrogen peroxide solution is used as a medicine for disinfecting and cleaning contact lenses, for example. Patent Document 4 detoxifies hydrogen peroxide while effectively sterilizing the contact lens with hydrogen peroxide by introducing a hydrogen peroxide decomposition catalyst while immersing the contact lens in an aqueous hydrogen peroxide solution. Disinfecting method is disclosed.

JP 2010-105864 A JP-A-8-257573 JP-A-61-186208 JP-A-6-226098

  However, when the object to be treated and the hydrogen peroxide decomposition catalyst coexist in the hydrogen peroxide solution and the disinfection of the object to be processed and the decomposition of hydrogen peroxide proceed simultaneously, the conventional catalyst has high disinfection for the object to be treated. It was difficult to increase both the effect and the low residual hydrogen peroxide concentration after a predetermined time. That is, if a catalyst having a large amount of active metal supported is used in order to reduce the residual hydrogen peroxide concentration after a predetermined time has elapsed, the hydrogen peroxide is decomposed in a short time, and the disinfection effect becomes insufficient. . On the other hand, if a catalyst having a small amount of active metal supported is used in order to enhance the disinfection effect, the residual hydrogen peroxide concentration cannot be reduced to a certain level or less within a predetermined time. In this case, a cleaning process for removing residual hydrogen peroxide from the object to be processed is necessary.

  The present invention has been made to solve the above-mentioned problems, and by allowing the material to be treated to coexist in the hydrogen peroxide solution, the material to be treated can be sufficiently sterilized, and after a predetermined time has passed, An object of the present invention is to provide a hydrogen peroxide decomposition catalyst capable of sufficiently reducing the residual concentration and a method for producing the catalyst. Another object of the present invention is to provide a disinfection method using hydrogen peroxide and the hydrogen peroxide decomposition catalyst in combination.

  The present invention is a hydrogen peroxide decomposition catalyst for decomposing hydrogen peroxide in a liquid phase into water and oxygen, comprising a carrier made of an inorganic oxide material having pores, Pt, Pd, And an active metal containing at least one element selected from the group consisting of Ir, Ru, Rh and Os, and the thickness of the layer on which the active metal is supported in the vicinity of the surface of the carrier is 0.01 to 0.25 mm. A catalyst is provided. The “layer in which the active metal is supported in the vicinity of the surface of the carrier” as used herein refers to a region within 2.0 mm from the surface of the carrier (hereinafter, this region is referred to as “near the surface of the carrier”). This refers to a layer in which 9% or more of the active metal is supported in the vicinity of the surface of the carrier relative to the total content of the active metal supported. The thickness of the layer on which the active gold is supported can be determined by elemental mapping. The concentration distribution of the active metal in the cross section of the support is measured with EPMA (for example, EPMA manufactured by Shimadzu Corporation), and the measurement result shows the support. By calculating the distribution of the content of the active metal with respect to the distance from the surface, the thickness of the layer in which the active metal is supported in the vicinity of the surface of the carrier can be obtained.

  By forming the active metal layer relatively thick in the vicinity of the surface of the support, the concentration of the active metal on the surface of the catalyst becomes lower than when the layer containing the same amount of active metal is formed thin. For this reason, even if the catalyst and the object to be treated are coexistent in the hydrogen peroxide solution, it is possible to suppress excessive decomposition of hydrogen peroxide from the initial stage, and a sufficiently high disinfection effect can be obtained. On the other hand, with the passage of time, the hydrogen peroxide solution soaks into the active metal layer (near the surface of the support) and comes into contact with a sufficient amount of the active metal. For this reason, the residual concentration of hydrogen peroxide after a predetermined time can be reduced to a sufficiently low level.

As the inorganic oxide material constituting the carrier, at least one material selected from the group consisting of aluminum oxide, magnesium oxide, silica and titanium oxide can be used. In the present invention, the carrier may have a specific surface area of 1 to 30 m ² / g. The specific surface area can be determined by a gas adsorption method, and a specific surface area measuring device manufactured by Shimadzu Corporation can be used as the measuring device.

  As the carrier, aluminum oxide in which Na or Cl is supported at least near the surface can be used. When using a molded body of aluminum oxide impregnated with Na as a carrier, the carrier is a molded body made of aluminum oxide in any one of an aqueous sodium hydroxide solution, an aqueous sodium nitrate solution and an aqueous sodium carbonate solution before impregnating with an active metal. Can be obtained by firing the molded body (Na pretreatment). When an aluminum oxide molded body impregnated with Cl is used as a carrier, the carrier is formed by immersing a molded body made of aluminum oxide in an aqueous hydrogen chloride solution before impregnating the active metal, and then firing the molded body. (Cl pretreatment).

  When hydrogen peroxide is decomposed in a liquid phase using a conventional catalyst, oxygen bubbles generated by the decomposition adhere to the surface of the catalyst. The bubbles gradually increase on the catalyst surface, and the contact between the aqueous solution and the catalyst is hindered to hinder the progress of the reaction. On the other hand, in the case of a catalyst in which an active metal is supported on a support that has undergone Na pretreatment or Cl pretreatment, the fine bubbles generated at the active points on the catalyst surface leave the catalyst surface as they are, so these bubbles are bonded together. And it can suppress that it becomes a big bubble. For this reason, hydrogen peroxide can contact the active sites efficiently, and the hydrogen peroxide resolution can be maintained for a sufficiently long time without mechanical stirring.

  The present inventors infer the following as to the main reason why the fine bubbles generated at the active points on the catalyst surface leave the catalyst surface as they are. That is, when the carrier is impregnated with Na or Cl, the hydrophilicity of the catalyst surface is improved and the water wettability is improved, so that the surface separation of the bubbles is promoted at the active point on the catalyst surface. In addition, since the support is impregnated with Na or Cl, the active metal forms extremely fine clusters (for example, a particle diameter of 1 nm or less), and the surface of the support is in a state in which such clusters are highly dispersed. It is carried on. As shown in FIG. 1A, when hydrogen peroxide touches a fine cluster A, the cluster A is divided into two clusters B and water is released. When Na or Cl is present on the carrier, the two clusters B are in an unstable state because the distance between them is short, and becomes one cluster A again. At the same time as this cluster re-formation occurs, fine bubbles are released each time.

  On the other hand, as shown in FIG. 1B, in the conventional catalyst in which the active metal is not sufficiently dispersed, the divided cluster D is different from the cluster C in terms of the stability level. Since there is not much, priority is given to the decomposition reaction of hydrogen peroxide rather than coalescing again to form cluster C. For this reason, the reverse reaction (the reaction from the structure D to the structure C) does not proceed easily, and oxygen is not released but each time oxygen atoms are accumulated on the surface. When oxygen atoms accumulate to some extent, a large amount of oxygen molecules are likely to be generated at one time.

  Further, the presence of Na or Cl on the support can prevent the aggregation of highly dispersed active metals (clusters) and can sufficiently suppress the deterioration of the catalyst. For this reason, compared with the conventional catalyst, durability with respect to repeated use can be improved dramatically.

  The present invention provides a method for producing the hydrogen peroxide decomposition catalyst. The production method is a method for producing a hydrogen peroxide decomposition catalyst for decomposing hydrogen peroxide in a liquid phase into water and oxygen, comprising a step of preparing a carrier made of an inorganic oxide material having pores, and Pt An active metal containing at least one element selected from the group consisting of Pd, Ir, Ru, Rh and Os has a thickness of 0.01 to 0. And a step of impregnating the carrier so as to be 25 mm.

  According to the above manufacturing method, by coexisting with an object to be processed in a hydrogen peroxide solution, the object to be processed can be sufficiently sterilized and a residual concentration of hydrogen peroxide can be sufficiently reduced after a predetermined time has elapsed. A hydrogenolysis catalyst can be obtained.

  The present invention provides a disinfection method using hydrogen peroxide and the above catalyst in combination. The disinfection method includes a step of immersing the catalyst and the object to be treated in a hydrogen peroxide solution, and in this step, the object to be treated is disinfected with hydrogen peroxide and the decomposition reaction of hydrogen peroxide by the catalyst. To reduce the hydrogen peroxide concentration.

  According to the above-mentioned disinfection method, disinfection is performed with hydrogen peroxide contained in the solution in which the object to be treated is immersed, and after a predetermined time has elapsed, the decomposition reaction of hydrogen peroxide by the catalyst proceeds and the remaining amount of hydrogen peroxide is increased. Can be made sufficiently low. Such a disinfection method is useful, for example, when the contact lens after use is immersed in a liquid overnight.

  According to the present invention, hydrogen peroxide can coexist with an object to be treated in a hydrogen peroxide solution to sufficiently disinfect the object to be treated and sufficiently reduce the residual concentration of hydrogen peroxide after a predetermined time. A decomposition catalyst and a production method thereof are provided, and a disinfection method using hydrogen peroxide and the hydrogen peroxide decomposition catalyst in combination is provided.

FIG. 1 (a) is a diagram showing a reaction mechanism of a catalyst in which an active metal is composed of minute clusters, and FIG. 1 (b) is a diagram showing a reaction mechanism of a conventional catalyst. FIG. 2 is a schematic cross-sectional view showing an embodiment of the catalyst according to the present invention. FIG. 3 is a graph showing the results of Examples 1 and 4. FIG. 4 is a graph showing the results of Examples 5 and 8. FIG. 5 is a graph showing the results of Examples 9 and 11.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

<Hydrogen peroxide decomposition catalyst and production method thereof>
The catalyst 10 shown in FIG. 2 is for decomposing hydrogen peroxide in the liquid phase into water and oxygen. The catalyst 10 includes a carrier 1 and an active metal supported on the carrier 1. The method for producing the catalyst 10 includes a step of preparing a carrier 1 made of an inorganic oxide material having pores, and an active metal containing at least one element selected from the group consisting of Pt, Pd, Ir, Ru, Rh, and Os. In the vicinity of the surface of the carrier 1 so that the thickness of the layer 1a on which the active metal is carried is 0.01 to 0.25 mm.

  The carrier 1 is not particularly limited as long as it is made of an inorganic oxide material having pores, but at least the vicinity of the surface is preferably made of a material mainly composed of alumina (aluminum oxide). The “main component” of the material here means a component that occupies a content of more than 50% by mass based on the total mass of the material. The catalyst 10 shown in FIG. 2 uses a rectangular parallelepiped molded body as the carrier 1, but the shape of the molded body is not limited to a rectangular parallelepiped, and may be a columnar shape or a cylindrical shape depending on the use and use conditions of the catalyst 10. May be. Examples of inorganic oxide materials other than alumina include magnesia (magnesium oxide), zirconia (zirconium oxide), and titania (titanium oxide).

  When an alumina compact is employed as the carrier 1, the type of alumina may be either α-alumina or γ-alumina. Conventional catalysts mainly use γ-alumina which is porous and has a large specific surface area in order to increase the contact efficiency between the reactant and the active metal. On the other hand, in this embodiment, α-alumina having a relatively small specific surface area may be used as the molded body having pores. In the present embodiment, as described later, the active metal forms a very fine cluster (for example, a particle diameter of 1 nm or less). By supporting these clusters in a highly dispersed state on the surface of the support, even if an inorganic oxide material having a specific surface area smaller than that of a conventional support is used as the support, It is possible to suppress or improve the decrease in contact efficiency. In addition, the carrier having a small specific surface area has many pores having a small pore diameter, and the mass transfer rate of the reaction product (hydrogen peroxide aqueous solution) and the generated gas (oxygen gas) becomes slow. In the liquid phase reaction, it is known that the influence of the pore diameter on the moving speed is particularly large. When a support having an excessively small specific surface area is used, the active metal is supported in a large number of small pores with a large surface area, which causes a problem of a decrease in mass transfer rate. Therefore, there is a high possibility that the small pores are filled with gas and the contact between the active metal and the solution is hindered. From these viewpoints, selection of a carrier having an appropriate specific surface area is an important point in controlling the reaction of the aqueous hydrogen peroxide solution.

In this embodiment, by using α-alumina having a specific surface area of 1 to 30 m ² / g (more preferably 1 to ³ m ² / g), both high mechanical strength and excellent dispersibility of the active metal are obtained. Can be obtained.

  Preferable examples of the carrier 1 include a fired body obtained by press-molding alumina powder and firing at 1000 to 1100 ° C. The fired body may contain magnesia, zirconia or titania as a component other than alumina.

When a titania shaped body is employed as the carrier 1, it may be either anatase type or rutile type. In order to increase the contact efficiency between the reactant and the active metal, the conventional catalyst mainly uses anatase titania having a large specific surface area and being porous. In the present embodiment, rutile titania having a relatively small specific surface area may be used as the molded body having pores. By using titania having a specific surface area of 1 to 30 m ² / g (more preferably 1 to 9 m ² / g), a catalyst that achieves both high mechanical strength and high dispersibility of the active metal is obtained. be able to.

  As the carrier 1, it is preferable to use a carrier in which Na or Cl is supported on a molded body such as alumina. Such a carrier 1 can be obtained by impregnating a molded body with Na or Cl. Na or Cl in the molded body plays a role of dispersing the active metal when the active metal is supported on the support 1, and also plays a role of suppressing the movement of the active metal on the support 1 after the active metal is supported. It is guessed. As a result, the amount of active metal supported can be reduced and the active metal can be effectively prevented from agglomerating, and the durability of the catalyst 10 against repeated use can be dramatically improved.

  When carrier 1 is formed by impregnating Na into an alumina molded body, carrier 1 is obtained by immersing the molded body in one of an aqueous sodium hydroxide solution, an aqueous sodium nitrate solution and an aqueous sodium carbonate solution for about 0.5 to 2 hours. Then, it can obtain by baking a molded object for about 1 to 3 hours on 500-800 degreeC temperature conditions (Na pretreatment process). From the viewpoint of obtaining the above effect stably and highly, the ratio of the number of moles of Na to the number of moles of active metal (Na / active metal mole ratio) in the catalyst 10 is preferably 0.5 to 50, more preferably. Is 1-20. The number of moles of Na can be determined by atomic absorption, and the number of moles of active metal can be determined from the amount supported.

  When the carrier 1 is formed by impregnating an alumina molded body with Cl, the carrier 1 can be obtained by immersing the molded body in a hydrogen chloride aqueous solution at a temperature of 50 to 90 ° C. for about 0.5 to 2 hours. (Cl pretreatment step). From the viewpoint of obtaining the above effect stably and highly, the ratio of the number of moles of HCl in the catalyst 10 (value obtained by converting the number of moles of Cl to the number of moles of HCl) and the number of moles of active metal (HCl / active metal mole ratio). ) Is preferably 1-20, more preferably 1-11. The number of moles of HCl can be determined by potentiometric titration.

  The active metal has a resolution of hydrogen peroxide and contains at least one element selected from the group consisting of Pt, Pd, Ir, Ru, Rh, and Os. In order to support the active metal on the carrier 1, first, the carrier 1 is immersed in a chloride solution, nitrate solution, or sulfate solution of these metals under a temperature condition of room temperature to 90 ° C. for about 10 to 120 minutes. After drying the support 1 over 2 hours, it is obtained by reducing the support 1 for about 0.5 to 2 hours in the presence of hydrogen at a temperature of 200 to 500 ° C. (more preferably 200 to 400 ° C.). Can do. If the reduction temperature is less than 200 ° C., the activity of the catalyst 10 tends to be insufficiently developed, and if it exceeds 500 ° C., the active metal tends to aggregate due to the reduction treatment.

  The catalyst 10 is adjusted so that the thickness of the layer 1a carrying the active metal is 0.01 to 0.25 mm. If the thickness of the layer 1a is outside the above range, it is difficult to achieve both a high disinfection effect due to hydrogen peroxide and a low residual hydrogen peroxide concentration after a predetermined time. From the viewpoint of ensuring both of these, the thickness of the layer 1a is preferably 0.05 to 0.25 mm, and more preferably 0.1 to 0.25 mm.

  The thickness of the layer 1a is adjusted by appropriately setting the time and temperature at which the carrier 1 is immersed in a chloride solution of active metal, the concentration of the chloride solution, etc., according to the specific surface area and porosity of the carrier 1. be able to.

  From the viewpoint of obtaining high activity, the active metal is preferably a cluster composed of a plurality of Pt atoms (hereinafter referred to as “Pt cluster”). The particle size of the Pt cluster is preferably 1 nm or less, more preferably 0.6 nm or less. When the particle size of the Pt cluster is 1 nm or less, a high degree of dispersion of Pt can be achieved, whereby hydrogen peroxide can be decomposed at a sufficiently high reaction rate. The lower limit of the particle size of the Pt cluster is about 0.5 nm.

  Pt forming the Pt cluster preferably has an average coordination number in the range of 3-6, and more preferably in the range of 3-5. In the Pt cluster, the distance between two Pt atoms is preferably 0.254 to 0.273 nm. When the average coordination number of Pt and the distance between atoms are within the above ranges, the durability of the catalyst 10 against repeated use can be significantly improved. The “average coordination number” of Pt is the average value of the coordination number of the nearest Pt atom around the Pt atom (Pt—Pt coordination number). The structure of Pt clusters (particle size, average coordination number, and distance between Pt atoms) can be measured by X-ray absorption fine structure analysis (XAFS). The X-ray absorption fine structure analysis method can be performed using, for example, BL-12C of High Energy Accelerator Research Organization.

The amount of Pt supported is preferably 0.01 to 0.5 mg / cm ² , more preferably 0.01 to 0.3 mg / cm ² on the basis of the geometric surface area of the carrier 1 (outer surface area of the carrier 1). ² , More preferably, it is 0.01-0.2 mg / cm < ² >. If the supported amount of Pt is less than 0.01 mg / cm ² , decomposition of hydrogen peroxide tends to be insufficient, while if it exceeds 0.5 mg / cm ² , the cost tends to increase.

<Disinfection method>
The disinfection method according to this embodiment includes a step of immersing the catalyst 10 and the object to be processed in a hydrogen peroxide solution. In this process, the object to be treated is disinfected with hydrogen peroxide and the decomposition reaction of hydrogen peroxide is advanced by the catalyst 10 to reduce the hydrogen peroxide concentration.

What is necessary is just to set suitably the density | concentration and quantity of hydrogen peroxide aqueous solution (hydrogen peroxide solution) used as disinfection liquid according to the use and disinfection time of a to-be-processed object. For example, when the catalyst 10 is used to detoxify hydrogen peroxide used for disinfecting contact lenses, the geometric surface area of the carrier 1 (outer surface area of the carrier 1) is the amount of hydrogen peroxide solution used for disinfecting contact lenses. Is preferably 0.2 to ² cm ² / ml, more preferably 0.2 to 1.5 cm ² / ml, still more preferably 1.0 to 1.5 cm ² / ml. When the catalyst 10 having a suitable amount of Pt supported on the carrier 1 whose outer surface area satisfies such conditions is immersed in an aqueous hydrogen peroxide solution (for example, a hydrogen peroxide concentration of 34000 ppm by mass) at room temperature, the excess after 10 minutes from the start of immersion. It is possible to sufficiently suppress decomposition of the hydrogen oxide solution exceeding 50% of the hydrogen peroxide concentration at the start (for example, up to 15000 ppm when the hydrogen peroxide concentration at the start of immersion is 34000 ppm by mass) Decomposition exceeding 40% (for example, up to 20000 ppm or less in the case of a hydrogen peroxide concentration of 34,000 mass ppm at the start of immersion) can be sufficiently suppressed by optimizing the loading amount and cluster size. On the other hand, after 4 hours from the start of immersion, the hydrogen peroxide concentration is lowered to 0.3% of the initial hydrogen peroxide concentration (for example, 100 ppm in the case of 34,000 mass ppm of hydrogen peroxide at the start of immersion) or less. By optimizing the active metal loading and cluster size, 0.2% of the hydrogen peroxide concentration at the start (for example, 70 mass ppm when the hydrogen peroxide concentration at the start of immersion is 34000 mass ppm) Hereinafter, it can be further reduced to 0.1% or less of the hydrogen peroxide concentration at the start (for example, 50 mass ppm when the hydrogen peroxide concentration at the start of immersion is 34000 mass ppm).

  According to the disinfection method according to the present embodiment, the object to be processed is disinfected with hydrogen peroxide before being decomposed by the catalyst 10, and the catalyst 10 remains as time passes after the disinfection of the object to be processed is completed. Hydrogen peroxide can be decomposed and rendered harmless.

According to the catalyst 10, by coexisting with the object to be processed in the hydrogen peroxide solution, the object to be processed can be sufficiently sterilized, and the residual concentration of hydrogen peroxide can be sufficiently reduced after a predetermined time has elapsed. Therefore, as described below, a hydrogen peroxide solution can be used as a disinfectant, and the catalyst 10 can be applied to a technique that requires detoxification of hydrogen peroxide after disinfection. When the object to be treated is immersed in a disinfectant (hydrogen peroxide solution), the catalyst 10 is provided in a dedicated cup or container for pouring the disinfectant, or the catalyst 10 is immersed in the disinfectant together with the object to be treated. Alternatively, an apparatus designed to automatically immerse the catalyst 10 in the disinfecting solution after sterilizing for a certain period of time may be used. The catalyst and disinfecting method of the present invention can be used as a hydrogen peroxide solution or as a disinfectant for peroxide, for example, a catalyst for detoxifying peracetic acid in a liquid phase. A step of immersing the catalyst and the object to be treated in a peracetic acid solution, wherein in the step, the object to be treated is disinfected with peracetic acid and a decomposition reaction of peracetic acid by the catalyst is allowed to proceed. It is also used in disinfection methods that reduce the concentration. The catalyst of the present invention is also used as a catalyst for decomposing and detoxifying hydrogen peroxide adducts, for example, oxygen-based bleaching agents such as sodium percarbonate. It can also be used for a bleaching method in which bleaching is performed by dipping to bleach the material to be treated and decompose the bleaching agent in the solution.
(1) Disinfect contact lenses by immersing them in disinfectant.
(2) Disinfection by immersing a brush for hairdressing and beauty, a scalp / hair brush, a soap brush used for shaving, a brush for painting, a brush for cleaning, etc. in a disinfectant solution.
(3) Disinfect the denture by immersing it in the disinfectant solution.
(4) Disinfecting medical instruments such as endoscopes and catheters by immersing them in disinfectant.
(5) Disinfection by immersing surgical and obstetric / urological equipment (endoscope, etc.) and instruments (female, catheter, etc.) in disinfectant.
(6) Disinfection by immersing anesthesia equipment, artificial respiration equipment, artificial dialysis delivery, dental instruments and their auxiliary instruments, syringes, thermometers, plastic instruments, etc. in disinfectant.
(7) Disinfect by disinfecting parts in which the disinfectant is likely to remain in the inner hole, etc., or a device having a complicated structure that has conventionally required a long time for rinsing.
(8) The pipe is removed from the pump device for disinfecting the endoscope, and this pipe is immersed in a disinfectant solution for disinfection.
(9) In an emergency, disinfect by filling the water purification passage inside the water supply carrying box to purify the raw water into drinking water.
(10) Disinfection by immersing the toy in a disinfectant solution.

<Examples 1-4>
Although the thickness of the layer carrying Pt in the vicinity of the surface of the carrier is different, four types of catalysts were prepared so that the total amount of Pt was the same, and the thickness of the layer carrying Pt was hydrogen peroxide. The effect on the residual concentration of was investigated.

Example 1
First, a molded body made of α-alumina (shape: rectangular parallelepiped, specific surface area: 2 m ² / g, geometric surface area: 7 cm ² ) was prepared. After immersing the molded body in a 25 ° C. aqueous sodium hydroxide solution (concentration: 5% by mass) for 1 hour, the molded body was fired at 800 ° C. for 2 hours to obtain a carrier (Na pretreatment step). Next, the support was immersed in an aqueous solution of CPA (chloroplatinic acid) at 25 ° C. for 60 minutes, and then washed and dried. And the catalyst A was obtained by performing the reduction process of platinum over 1 hour at 300 degreeC. Table 1 shows the physical properties of Catalyst A.

(Examples 2 to 4)
Except for reducing the thickness of the layer carrying Pt while maintaining the total amount of Pt by shortening the time for immersing the carrier using a high concentration CPA aqueous solution, Catalysts B to D were obtained by the same treatment. Table 1 shows the physical properties of the catalysts B to D.

(Hydrogen peroxide decomposition treatment)
In order to evaluate the hydrogen peroxide resolution of the catalysts A to D, an aqueous hydrogen peroxide solution having a hydrogen peroxide concentration of 34000 mass ppm was prepared, and hydrogen peroxide was decomposed using each catalyst. After putting 5 ml of the hydrogen peroxide solution in the container, the hydrogen peroxide concentration (residual hydrogen peroxide concentration) was measured after 10 minutes and 4 hours from the time when each catalyst was immersed in the solution. Table 1 shows the results. FIG. 3 is a graph showing changes in residual hydrogen peroxide concentration when Catalyst A and Catalyst D are used.

<Examples 5 to 8>
Although the thickness of the layer carrying Pt in the vicinity of the surface of the carrier is different, four types of catalysts E to H are prepared so that the dispersion degree of Pt is the same, and the thickness of the layer carrying Pt is The effect on the residual concentration of hydrogen peroxide was investigated. The degree of dispersion of Pt was adjusted by appropriately setting the amount of Pt loaded and the loading conditions.

(Hydrogen peroxide decomposition treatment)
In order to evaluate the hydrogen peroxide resolution of the catalysts E to H, an aqueous hydrogen peroxide solution having a hydrogen peroxide concentration of 34,000 mass ppm was prepared, and hydrogen peroxide was decomposed using each catalyst. After putting 5 ml of the hydrogen peroxide solution in the container, the hydrogen peroxide concentration (residual hydrogen peroxide concentration) was measured after 10 minutes and 4 hours from the time when each catalyst was immersed in the solution. Table 2 shows the results. FIG. 4 is a graph showing changes in the residual hydrogen peroxide concentration when the catalyst E and the catalyst H are used.

<Examples 9 to 12>
Although the geometric surface areas of the supports are different, four types of catalysts IL are prepared so that the thicknesses of the layers on which Pt is supported are the same, and the geometric surface areas of the supports give the residual concentration of hydrogen peroxide. The impact was investigated.

(Hydrogen peroxide decomposition treatment)
In order to evaluate the hydrogen peroxide resolution of the catalysts I to L, an aqueous hydrogen peroxide solution having a hydrogen peroxide concentration of 34,000 mass ppm was prepared, and hydrogen peroxide was decomposed using each catalyst. After putting 5 ml of the hydrogen peroxide solution in the container, the hydrogen peroxide concentration (residual hydrogen peroxide concentration) was measured after 10 minutes and 4 hours from the time when each catalyst was immersed in the solution. Table 3 shows the results. FIG. 5 is a graph showing changes in the residual hydrogen peroxide concentration when Catalyst I and Catalyst K are used.

<Examples 13 to 15>
The effect of pretreatment on the carrier on the residual concentration of hydrogen peroxide was investigated.

(Example 13)
A molded body made of α-alumina (shape: rectangular parallelepiped, specific surface area: 2 m ² / g, mechanical surface area: 1.5 cm ² ) was prepared. Instead of performing the Na pretreatment step, a catalyst M was obtained by the same treatment as in Example 1, except that the Cl pretreatment step was carried out to obtain a support as follows. That is, the molded body was immersed in an aqueous chloroplatinic acid solution (concentration: 3% by mass) at 25 ° C. for 1 hour, and then dried to obtain a carrier (Cl pretreatment step). Table 4 shows the physical properties of the catalyst M.

(Example 14)
Catalyst N was obtained by the same treatment as in Example 13 except that the Cl pretreatment step was not carried out. Table 4 shows the physical properties of catalyst N.

(Example 15)
Example 14 is the same as Example 14 except that γ-alumina (shape: cuboid, specific surface area: 200 m ² / g, mechanical surface area: 1.5 cm ² ) was used as the support instead of the molded body comprising α-alumina. Catalyst O was obtained by the same treatment. Table 4 shows the physical properties of the catalyst O.

  In order to evaluate the hydrogen peroxide resolution of the catalysts M to O, an aqueous hydrogen peroxide solution having a hydrogen peroxide concentration of 34,000 mass ppm was prepared, and hydrogen peroxide was decomposed using each catalyst. After putting 5 ml of the hydrogen peroxide solution in the container, the hydrogen peroxide concentration (residual hydrogen peroxide concentration) was measured after 10 minutes and 4 hours from the time when each catalyst was immersed in the solution. Table 4 shows the results.

In addition, the specific surface area measured the specific surface area of the support | carrier using the Shimadzu Corporation specific surface area measuring apparatus. The mechanical strength was measured using a LLOYD material testing machine.

<Examples 16 to 19>
Instead of using an alumina compact as a carrier, a catalyst was prepared using a rutile titanium oxide compact and evaluated.

(Example 16)
A molded body (shape: rectangular solid, specific surface area: 8.5 m ² / g, mechanical surface area: 1.5 cm ² ) made of rutile type titanium oxide was prepared. A catalyst P was obtained in the same manner as in Example 1 except that the molded body was used instead of the molded body made of α-alumina. That is, the molded body was immersed in a 25 ° C. sodium hydroxide aqueous solution (concentration: 5 mass%) for 1 hour, and then the molded body was fired at 800 ° C. for 2 hours to obtain a carrier (Na pretreatment step). Next, the support was immersed in an aqueous solution of CPA (chloroplatinic acid) at 25 ° C. for 60 minutes, and then washed and dried. And the catalyst P was obtained by performing the reduction process of platinum over 1 hour at 300 degreeC. Table 5 shows the physical properties of the catalyst P.

(Example 17)
Instead of performing the Na pretreatment step, catalyst Q was obtained by the same treatment as in Example 16 except that the carrier was obtained by performing the Cl pretreatment step as follows. That is, the molded body was immersed in an aqueous chloroplatinic acid solution (concentration: 3% by mass) at 25 ° C. for 1 hour, and then dried to obtain a carrier (Cl pretreatment step). Table 5 shows the physical properties of Catalyst Q.

(Example 18)
Catalyst R was obtained by the same treatment as in Example 16 except that the Na pretreatment step was not carried out. Table 5 shows the physical properties of the catalyst R.

(Example 19)
Example 18 Although the thickness of the Pt-supported layer in the vicinity of the surface of the carrier is different, the concentration of the CPA aqueous solution and the time during which the carrier is immersed are changed so that the amount of Pt supported is the same. Catalyst S was obtained by the same treatment as in Example 1. Table 5 shows the physical properties of the catalyst S.

  In order to evaluate the hydrogen peroxide resolution of the catalysts M to O, an aqueous hydrogen peroxide solution having a hydrogen peroxide concentration of 34,000 mass ppm was prepared, and hydrogen peroxide was decomposed using each catalyst. After putting 5 ml of the hydrogen peroxide solution in the container, the hydrogen peroxide concentration (residual hydrogen peroxide concentration) was measured after 10 minutes and 4 hours from the time when each catalyst was immersed in the solution. Table 5 shows the results.

DESCRIPTION OF SYMBOLS 1 ... Support | carrier, 1a ... Layer in which active metal is supported, 10 ... Hydrogen peroxide decomposition catalyst.

Claims (8)

A hydrogen peroxide decomposition catalyst for decomposing hydrogen peroxide in a liquid phase into water and oxygen,
A carrier made of an inorganic oxide material having pores;
An active metal containing at least one element selected from the group consisting of Pt, Pd, Ir, Ru, Rh and Os supported on the carrier;
With
A catalyst having a thickness of 0.01 to 0.25 mm of a layer on which the active metal is supported in the vicinity of the surface of the support.   The catalyst according to claim 1, wherein the inorganic oxide material is at least one material selected from the group consisting of aluminum oxide, magnesium oxide, silica, and titanium oxide.   2. The catalyst according to claim 1, wherein the carrier is a molded body of aluminum oxide in which Na or Cl is supported at least in the vicinity of the surface. The catalyst as described in any one of Claims 1-3 whose specific surface area of the said support | carrier is 1-30 m < ² > / g. A method for producing a hydrogen peroxide decomposition catalyst for decomposing hydrogen peroxide in a liquid phase into water and oxygen,
Preparing a support made of an inorganic oxide material having pores;
An active metal containing at least one element selected from the group consisting of Pt, Pd, Ir, Ru, Rh and Os is used, and the thickness of the layer on which the active metal is supported in the vicinity of the surface of the carrier is 0.01. Impregnating the carrier to be ~ 0.25 mm;
A method comprising:   The inorganic oxide material is aluminum oxide, and after the molded body made of aluminum oxide is immersed in any one of an aqueous sodium hydroxide solution, an aqueous sodium nitrate solution, and an aqueous sodium carbonate solution before impregnating the active metal into the molded body. The method according to claim 5, further comprising a step of firing the molded body.   6. The method according to claim 5, wherein the inorganic oxide material is aluminum oxide, and the method further comprises the step of immersing the molded body in an aqueous hydrogen chloride solution before impregnating the active metal into the molded body made of aluminum oxide. A step of immersing the catalyst and the object to be treated according to any one of claims 1 to 4 in a hydrogen peroxide solution,
In this step, the disinfection method of disinfecting the object to be treated with hydrogen peroxide and lowering the hydrogen peroxide concentration by advancing a decomposition reaction of hydrogen peroxide with the catalyst.