JP5547455B2 - Hypochlorite decomposition catalyst, method for producing the same, and method for using the same - Google Patents

Description

  The present invention relates to a catalyst for decomposing hypochlorite, a method for producing the same and a method for using the same. More specifically, an inexpensive and highly active hypochlorite decomposition catalyst containing a Group 8, 9 or 10 element oxide and a Group 2 element compound, a method for producing the catalyst, and hypochlorite using the catalyst The present invention relates to a method for decomposing hypochlorite in contained wastewater and a method for oxidizing and decomposing atomic oxygen generated during decomposition by contacting with organic matter.

  Hypochlorite is contained in wastewater at factories that produce hypochlorite. In addition, when hypochlorite is added to and purified from organic wastewater from food processing plants, excessively added hypochlorite remains in the wastewater after treatment.

  Wastewater containing hypochlorite does not only give off a strange odor, but also produces toxic chlorine gas by contact with acid, and if released into a public water system untreated, it causes pollution.

  As a method for treating wastewater containing hypochlorite, there is a method in which hypochlorite is oxidized and decomposed using a reducing agent such as sulfite or hydrogen peroxide. However, in order to treat waste water containing a large amount of hypochlorite using this method, a large amount of reducing agent is required, and therefore the running cost is increased. Furthermore, in order to add a reducing agent according to the varying hypochlorite concentration, advanced technology and capital investment for that are required.

  There is a method of decomposing hypochlorite on a fixed bed catalyst containing nickel, cobalt and the like. This technique lowers the running cost because hypochlorite decomposes spontaneously by generating oxygen on the catalyst. However, since this catalyst contains metal as an active component, the activity is high when the amount of metal used is large, but the cost of the catalyst also increases.

  In order to reduce the cost of the fixed bed catalyst, it is necessary to increase the catalytic activity and dilute the active components. In general, catalytic activity can be achieved by increasing the surface area of the active ingredient. Diluents must be chosen that do not disintegrate during use. As described in Patent Document 1, since the pH of hypochlorite waste water is generally high, the diluent and binder are likely to collapse.

  In Patent Document 1, a catalyst that resists collapse is developed by using a thermoplastic resin binder such as polyvinylidene fluoride and integrating it with a fine metal oxide. However, since molding is performed by utilizing the thermoplasticity of the resin, there is a possibility that the metal oxide which is an active component is buried in the resin during the heat treatment and the catalytic activity is lowered.

  In Patent Document 2, a relatively inexpensive calcium aluminate cement is used as a diluent and a binder, and the complex composition and pore structure are controlled to achieve both high activity and resistance to disintegration. However, controlling the complex pore structure results in high manufacturing costs. In addition, calcium aluminate cement forms a cement gel in water and has a property of bonding particles. There is a possibility that the metal oxide as an active component is buried between the bonded calcium aluminate cement particles, and the catalytic activity is lowered.

  Using these technologies to prepare a hypochlorite decomposition catalyst with high activity and excellent decay resistance requires the use of expensive materials and control of the pore structure, making it difficult to reduce costs. It is.

  Further, Patent Document 3 states that a hypochlorous acid decomposition catalyst can be diverted as a catalyst for oxidizing pollutants using atomic oxygen generated during decomposition of hypochlorite.

  However, it is a catalyst that can be used both as a catalyst for decomposing hypochlorite in wastewater and as a catalyst for further oxidizing and decomposing organic substances in wastewater from the atomic oxygen generated at that time. However, a highly active catalyst has not been realized yet.

JP 56-97544 A Japanese translation of PCT publication No. 2001-500781 US Pat. No. 3,944,487

  An object of the present invention is to provide a hypochlorite decomposition catalyst using a raw material which is inexpensive and excellent in resistance to disintegration in a basic aqueous solution. Furthermore, another object of the present invention is to provide a method for decomposing hypochlorite using the above catalyst and a method for decomposing organic matter using atomic oxygen generated by this method.

  As a result of continual research to solve the above-mentioned problems, the present inventors have found that a catalyst containing a Group 8, 9, or 10 element oxide and a Group 2 element compound is much less than hypochlorite. It has excellent decomposing ability, and it is not necessary to control the pore structure, and it is possible to use inexpensive raw materials, and it is excellent in decay resistance even when used for a long time in wastewater containing hypochlorite with high pH. I found out. Based on this knowledge, the present invention was completed by examining in more detail.

That is, the present invention provides a catalyst for decomposing and generating an atomic oxygen hypochlorite, and a 8,9, or Group 10 element oxide and Group 2 element compound in including mixtures,
Magnesium 2 group elements, calcium, strontium, more than one kind of element selected from barium, hydroxide compounds, charcoal salts, hypochlorous characterized in that it is in the form of either sulfate The present invention relates to a catalyst for acid salt decomposition.

Furthermore, the catalyst is 8,9 or 10 element, wherein iron, cobalt, that Ru one or more metals der selected from nickel.

  Further, the catalyst is characterized in that it is a homogeneous mixture containing 5-70% by weight of Group 8, 9 or 10 element oxide and 95-30% by weight of Group 2 element compound.

  Further, the present invention is characterized in that water is added to a mixture of Group 8, 9 or 10 element oxide and Group 2 element compound, kneaded, extruded, and dried at 80 to 400 ° C. The present invention relates to a method for producing a chlorite decomposition catalyst.

  The present invention also relates to a method characterized by decomposing a hypochlorite aqueous solution to generate atomic oxygen in the presence of the catalyst.

  Furthermore, the method is characterized in that an aqueous hypochlorite solution is brought into contact with the catalyst under conditions of pH 6 to 14 and 10 to 100 ° C.

  Further, the present invention is characterized in that atomic oxygen generated by the above method is oxidatively decomposed by contacting with an organic substance.

  The catalyst of the present invention has a very excellent decomposition ability with respect to hypochlorite, and it is not necessary to control the pore structure, and an inexpensive raw material can be used. Excellent resistance to disintegration even in long-term use in acid-containing wastewater. Furthermore, atomic oxygen generated from hypochlorite can be effectively used for organic matter decomposition in wastewater, and contains hypochlorite of all sizes. Suitable for wastewater purification.

  The present invention is described in detail below.

  The catalyst of the present invention is a mixture containing a Group 8, 9 or 10 element oxide and a Group 2 element compound.

  The Group 8, 9, or 10 element is one or more metals selected from iron, cobalt, and nickel, and the oxide desirably has a high surface area.

  The group 2 element is one or more metals selected from magnesium, calcium, strontium, and barium, and the compound is composed of a hydroxide, an oxide, a carbonate, and a sulfate.

  The catalyst of the present invention is a homogeneous mixture comprising 5 to 70% by weight of Group 8, 9 or 10 elemental oxide and 95 to 30% by weight of Group 2 elemental compound. Here, in the molded article of the catalyst, when the content of the group 8, 9, or 10 element oxide exceeds 70% by weight, it is not preferable due to deterioration of moldability and high cost. The hypochlorite treatment is not preferable because of its low activity.

  Moreover, you may shape | mold by adding a shaping | molding adjuvant to these mixtures. Examples of the molding aid include methyl cellulose and magnesium stearate, and an arbitrary amount can be added.

The resulting catalyst, BET surface area is at least ^{30 m} 2 / g, especially 60~150m ² / g. The bulk density is 0.7 to 1.2 g / ml.

  The shape and size of the catalyst according to the present invention can be appropriately selected depending on the usage form. Generally, cylindrical pellets having a diameter of 1 to 6 mm and a length of about 3 to 20 mm are preferably used, but various shapes of catalysts, tablets, granules, and crushed particles can also be used. The pellets with the above diameter can be used directly for hypochlorite, and can be easily produced as compared with a catalyst that requires control of the pore structure.

  Depending on the composition of the catalyst, a stable Group 2 element compound can act as a molding aid in a hypochlorite aqueous solution while containing a large amount of Group 8, 9, or 10 element oxide as an active ingredient. it can. Therefore, both high activity and disintegration resistance can be achieved.

  Accordingly, the catalyst of the present invention does not collapse even if industrial-scale wastewater is continuously treated, because the molded body does not powder or crack.

  As a method for producing a catalyst according to the present invention, for example, when producing general extruded cylindrical pellets, a kneader such as a kneader is used to mix a predetermined amount of Group 8, 9, or 10 element oxide and Group 2 element compound. And 20 to 50% by weight of water is added to the mixed powder and kneaded. This mixed powder is obtained by mixing 50% by weight of a Group 2 element compound with 50% by weight of a Group 8, 9 or 10 element oxide.

  The obtained mixture is formed into a cylindrical pellet using an extruder or a disk pelleter and a die having a predetermined shape, and dried at a temperature of 80 to 400 ° C, preferably 100 to 300 ° C. When the pellets are dried at 80 ° C. or lower, the drying efficiency is poor. When the pellets are dried at a temperature exceeding 400 ° C., the activity decreases because the group 8, 9, or 10 element oxide is sintered at a high temperature.

  The method of using the catalyst according to the present invention is not particularly limited and can be used for a moving bed or a fluidized bed, but is usually used for a fixed bed. For example, it is possible to remove the hypochlorite in the effluent safely and efficiently by filling the cylinder with the catalyst and circulating the effluent containing the hypochlorite.

  As hypochlorite, for example, sodium hypochlorite, potassium hypochlorite, or calcium hypochlorite can be suitably used. Examples of the alkaline aqueous solution used with these hypochlorites include aqueous solutions of sodium hydroxide, potassium hydroxide, and the like.

  In the method of the present invention, an aqueous hypochlorite solution is brought into contact with the catalyst under conditions of pH 6 to 14 and 10 to 100 ° C. The concentration of the hypochlorite aqueous solution to be used can be appropriately determined according to the application.

  The catalyst according to the present invention can also be used as a catalyst for oxidizing pollutants using atomic oxygen produced during the decomposition of hypochlorite.

  For example, wastewater containing organic matter can be brought into contact with the catalyst together with the hypochlorite aqueous solution. There is no restriction | limiting in particular as this organic matter containing waste_water | drain, Organic waste water etc. which come from a food processing factory etc. are included. Here, the amount of the hypochlorite aqueous solution to be coexisted is preferably 1 to 100 times the theoretical amount necessary to oxidatively decompose the organic matter contained in the wastewater, and is 1 to 10 times the weight. It is more preferable.

  The catalyst according to the present invention can be used as a decomposition catalyst for oxidizing agents such as hypochlorite, and has strong activity as an oxidation catalyst for pollutants using oxidizing agents, and can be used effectively.

  Hereinafter, although the preparation example of the catalyst concerning the specific Example of this invention and the Example using those catalysts are demonstrated in detail, this invention is not limited to these.

(Catalyst performance test)
100 ml of 0.28 mol L ⁻¹ NaClO aqueous solution adjusted to pH 10 with NaOH was heated to 75 ° C., and the amount of oxygen generated after ¹ hour from the introduction of 10 g of the catalyst was examined. Furthermore, it was left to stand for 24 hours and the presence or absence of collapse was confirmed visually.

Example 1
Nickel oxide 300 g and calcium hydroxide 600 g were kneaded and extruded to 3 mm in diameter and 5 to 7 mm in length using a disk pelleter. Next, it was dried at 150 ° C. for 10 hours to obtain a catalyst. 100 ml of 0.28 mol L ⁻¹ NaClO aqueous solution adjusted to pH 10 with NaOH was heated to 75 ° C., and the amount of oxygen generated after ¹ hour from the introduction of 10 g of the catalyst was examined. Furthermore, it was left to stand for 24 hours and the presence or absence of collapse was confirmed visually. Table 1 shows the results of the decay of the catalyst and the amount of oxygen generated.

(Example 2)
Nickel oxide 300 g, calcium hydroxide 300 g, and magnesium hydroxide 300 g were kneaded and extruded to a diameter of 3 mm and a length of 5 to 7 mm using a disk pelleter. Next, it was dried at 150 ° C. for 10 hours to obtain a catalyst. 100 ml of 0.28 mol L ⁻¹ NaClO aqueous solution adjusted to pH 10 with NaOH was heated to 75 ° C., and the amount of oxygen generated after ¹ hour from the introduction of 10 g of the catalyst was examined. Furthermore, it was left to stand for 24 hours and the presence or absence of collapse was confirmed visually. Table 1 shows the results of the decay of the catalyst and the amount of oxygen generated.

(Comparative Example 1)
Nickel oxide 300 g and alumina 600 g were kneaded and extruded to 3 mm in diameter and 5 to 7 mm in length using a disk pelleter. Next, it was dried at 150 ° C. for 10 hours to obtain a catalyst. 100 ml of 0.28 mol L ⁻¹ NaClO aqueous solution adjusted to pH 10 with NaOH was heated to 75 ° C., and the amount of oxygen generated after ¹ hour from the introduction of 10 g of the catalyst was examined. Furthermore, it was left to stand for 24 hours and the presence or absence of collapse was confirmed visually. The results of decay of the catalyst and the amount of oxygen generated are shown in Table 2.

(Comparative Example 2)
Nickel oxide 300 g and water glass 50 g were kneaded and formed into a diameter of 10 mm and a length of 9 to 10 mm using a tablet molding machine. 100 ml of 0.28 mol L ⁻¹ NaClO aqueous solution adjusted to pH 10 with NaOH was heated to 75 ° C., and the amount of oxygen generated after ¹ hour from the introduction of 10 g of the catalyst was examined. Furthermore, it was left to stand for 24 hours and the presence or absence of collapse was confirmed visually. Table 2 shows the results of oxygen generation amount of the obtained catalyst.

  From the results of Tables 1 and 2 above, the catalyst containing the Group 8, 9 or 10 element oxide and the Group 2 element compound of the present invention has both the Group 8, 9 or 10 element oxide and the Group 2 element compound. It has been shown that the catalyst does not decay and allows both high oxygen evolution as compared to a catalyst with no composition.

Claims (7)

In a mixture for decomposing hypochlorite and generating atomic oxygen, comprising a group 8, 9, or 10 element oxide and a group 2 element compound ,
Magnesium 2 group elements, calcium, strontium, more than one kind of element selected from barium, hydroxide compounds, charcoal salts, hypochlorous characterized in that it is in the form of either sulfate Catalyst for acidolysis. 8, 9, or Group 10 element, iron, cobalt, according to claim 1, wherein the catalyst characterized by Oh Rukoto with one or more elements selected from nickel.   3. The catalyst according to claim 1, wherein the catalyst is a homogeneous mixture containing 5 to 70% by weight of Group 8, 9 or 10 element oxide and 95 to 30% by weight of Group 2 element compound. A method for producing a hypochlorite decomposition catalyst, comprising adding water to the mixture according to claim 1, kneading, extruding, and drying at 80 to 400 ° C.   A method comprising decomposing an aqueous hypochlorite solution to generate atomic oxygen in the presence of the catalyst according to any one of claims 1 to 3.   The method according to claim 5, wherein the aqueous hypochlorite solution is brought into contact with the catalyst according to any one of claims 1 to 3 under conditions of pH 6 to 14 and 10 to 100 ° C.   7. A method comprising oxidizing the atomic oxygen generated by the method according to claim 5 or 6 in contact with an organic substance.