JP7067035B2 - Ammonia oxidation method - Google Patents

Description

The present invention relates to a method for oxidizing ammonia.

Ammonia gas and aqueous ammonia are widely used for industrial purposes in chemical plants, power plants, sewage treatment facilities, and the like. As a method for treating ammonia after use, for example, Patent Document 1 describes a method for oxidizing ammonia to nitrogen and water in the presence of a catalyst containing platinum, an inorganic oxide and zeolite.

International release WO2015 / 099024

An object of the present invention is to provide a method for oxidizing ammonia at a high conversion rate in the presence of a more readily available metal-containing catalyst.

The present invention provides:
[1] Ammonia oxidation including a step of oxidizing ammonia in an ammonia-containing gas to nitrogen and water in the presence of a catalyst in which ruthenium and / or a ruthenium compound is supported on a carrier containing rutyl crystalline titanium oxide. Method.
[2] The method for oxidizing ammonia according to [1], wherein the step of oxidizing ammonia to nitrogen and water is performed by bringing an ammonia-containing gas containing oxygen into contact with the catalyst.
[3] The method for oxidizing ammonia according to [1] or [2], wherein the catalyst is a catalyst in which ruthenium oxide is supported on the carrier.
[4] The catalyst is a catalyst in which at least one oxide selected from the group consisting of silicon oxide, zirconium oxide, aluminum oxide, niobium oxide and tin oxide is further supported on the carrier [1] to [3]. The method for oxidizing aluminum according to any one of the above items.
[5] An ammonia-containing gas oxidizing apparatus comprising a catalyst in which ruthenium and / or a ruthenium compound is supported on a carrier containing rutile crystalline titanium oxide.
[6] A dispersal tower having a dissipating means for dissipating an ammonia-containing gas from an ammonia-containing aqueous solution,
An ammonia-containing aqueous solution processing apparatus provided with the ammonia-containing gas oxidizing apparatus according to [5].

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for oxidizing ammonia at a high conversion rate in the presence of a catalyst containing a more easily available metal.

〔catalyst〕
The catalyst used in the method for oxidizing ammonia according to the present invention is a catalyst in which ruthenium and / or a ruthenium compound is supported on a carrier containing ruthenium crystalline titanium oxide.
As used herein, the term "catalyst in which ruthenium and / or a ruthenium compound is supported on a carrier containing rutile crystalline titanium oxide" refers to the surface and / or pores of a carrier containing rutile crystalline titanium oxide. Means a catalyst to which ruthenium and / or ruthenium compounds are attached.

<Ruthenium compound>
Examples of the ruthenium compound include ruthenium oxide, ruthenium hydroxide, ruthenium chloride, chlororuthenium acid salt, chlororuthenium acid salt hydrate, ruthenium acid salt, ruthenium oxychloride, ruthenium oxychloride salt, ruthenium ammine complex, and ruthenium ammine. Examples thereof include chloride of the complex, ruthenium bromide, ruthenium carbonyl complex, ruthenium organic acid salt, ruthenium nitrosyl complex, ruthenium phosphine complex and the like.
Examples of ruthenium oxide include RuO ₂ .
Examples of ruthenium hydroxide include Ru (OH) ₃ .
Examples of ruthenium chloride include RuCl _{3 ,} RuCl trihydrate and the like.
Examples of the chlororuthenium salt include K ₃ RuCl ₆ , [RuCl ₆ ] ^3- , and K ₂ RuCl ₆ .
Examples of the chlororuthenium acid salt hydrate include [RuCl ₅ (H ₂ O) ₄ ] ^2- , [RuCl ₂ (H ₂ O) ₄ ] ⁺ and the like.
Examples of the ruthenium acid salt include K ₂ RuO ₄ .
Examples of ruthenium oxychloride include Ru ₂ OCl ₄ , Ru ₂ OCl ₅ , and Ru ₂ OCl ₆ .
Examples of the salt of ruthenium oxychloride include K ₂ Ru _{2 OCl 10} , Cs ₂ Ru ₂ OC l 4 and the like.
Examples of the ruthenium ammine complex include [Ru (NH ₃ ) ₆ ] ²⁺ , [Ru (NH ₃ ) ₆ ] ³⁺ , and [Ru (NH ₃ ) ₅ H ₂ O] ²⁺ .
Chlorides of the ruthenium ammine complex include [Ru (NH ₃ ) ₅ Cl] ²⁺ , [Ru (NH ₃ ) ₆ ] Cl ₂ , [Ru (NH ₃ ) ₆ ] Cl ₃ , [Ru (NH ₃ ) ₆ ] Br ₃ and the like can be mentioned.
Examples of ruthenium bromide include RuBr ₃ , _RuBr trihydrate and the like.
Examples of the ruthenium carbonyl complex include Ru (CO) ₅ and Ru ₃ (CO) ₁₂ .
Examples of the ruthenium organic acid salt include [Ru ₃ O (OCOCH ₃ ) ₆ (H ₂ O) ₃ ] OCOCH trihydrate and Ru ₂ (RCOO) ₄ Cl ₍ R = alkyl group having 1-3 carbon atoms). Can be mentioned.
Ruthenium nitrosyl complexes include K ₂ [RuCl ₅ NO)], [Ru (NH ₃ ) ₅ (NO)] Cl ₃ , [Ru (OH) (NH ₃ ) ₄ (NO)] (NO ₃ ) ₂ , Ru. (NO) (NO ₃ ) ₃ and the like.
The ruthenium compound is preferably ruthenium oxide, ruthenium chloride, ruthenium bromide, a salt of ruthenium acid, a ruthenium nitrosyl complex, and more preferably ruthenium oxide.

The content of ruthenium and / or the ruthenium compound in the catalyst is preferably 0.1 to 20% by weight, more preferably 0.5 to 10% by weight, still more preferably 1 to 5% by weight, based on metallic ruthenium.
The content of ruthenium and / or ruthenium compound is 0.1 to 20% by weight based on metallic ruthenium, where the total amount of ruthenium and / or ruthenium compound and the carrier containing ruthenium crystalline titanium oxide is 100% by weight. %, More preferably 0.5 to 10% by weight, even more preferably 1 to 5% by weight.

<Carrier containing rutile crystalline titanium oxide>
The carrier in the catalyst may contain at least rutile crystalline titanium oxide, and may further contain anatase crystalline titanium oxide.
From the viewpoint of catalytic activity, the content of rutile crystalline titanium oxide in the titanium oxide contained in the carrier is preferably 20% by weight or more, with the total amount of titanium oxide contained in the carrier being 100% by weight. By weight% or more is more preferable, 80% by weight or more is further preferable, and 90% by weight or more is further preferable.
The carrier may contain a metal oxide other than titanium oxide. Further, it may contain a composite oxide of titanium oxide and another metal oxide. Further, it may be a mixture of titanium oxide and other metal oxides. Examples of metal oxides other than titanium oxide include aluminum oxide, silicon oxide, and zirconium oxide.

Examples of the method for preparing rutile crystalline titanium oxide include the following methods.
After dropping and dissolving titanium tetrachloride in ice-cooled water, neutralize it with an aqueous ammonia solution at a temperature of 20 ° C or higher to generate titanium hydroxide (orthotitanic acid), and then wash the generated precipitate with water to produce chlorine ions. (Catalyst Preparation Chemistry, 1989, p. 211, Kodansha);
A method in which a reaction gas is prepared by passing an oxygen-nitrogen mixed gas through a titanium tetrachloride evaporator, introduced into the reactor, and reacted at 900 ° C. or higher (Catalyst Preparation Chemistry, 1989, p. 89, Kodansha);
A method of hydrolyzing titanium tetrachloride in the presence of ammonium sulfate and then firing it (for example, Catalyst Engineering Course, 10 Elemental Catalyst Handbook, 1978, p. 254, Chijin Shokan).
A method for calcining titanium oxide in the form of anatase crystals (for example, metal oxide and composite oxide, 1980, p. 107, Kodansha);
Method of heating and hydrolyzing an aqueous solution of titanium chloride; and after mixing an aqueous solution of a titanium compound such as titanium sulfate or titanium chloride with rutyl crystalline titanium oxide powder, heat hydrolysis or alkaline hydrolysis is performed, and then the temperature is around 500 ° C. How to bake with.
Further, as the rutile crystal form titanium oxide, a commercially available product may be used.

The carrier can be obtained by molding rutile crystalline titanium oxide into a desired shape. When the carrier contains a metal oxide other than the rutile crystalline titanium oxide, it can be obtained by molding a mixture of the rutile crystalline titanium oxide and the other metal oxide into a desired shape. ..

The titanium oxide containing rutile crystal form titanium oxide used in the present invention refers to those containing rutile crystals obtained by measuring the ratio of rutile crystals to anatase crystals in titanium oxide by an X-ray diffraction analysis method. .. Various sources are used as X-ray sources. For example, copper Kα ray and the like can be mentioned. When copper Kα rays are used, the ratio of rutile crystals and the ratio of anatase crystals are the intensity of the diffraction peak of 2θ = 27.5 degrees on the (110) plane and 2θ = 25.3 degrees on the (101) plane, respectively. It is determined using the intensity of the diffraction peak of. The carrier used in the present invention is a carrier having a peak intensity of rutile crystals and a peak intensity of anatase crystals, or a carrier having a peak intensity of rutile crystals. That is, it may be a carrier having both a diffraction peak of a rutile crystal and a diffraction peak of an anatase crystal, or a carrier having only a diffraction peak of a rutile crystal.

The catalyst is in the rutyl crystal form for the purpose of inhibiting the adsorption of substances that cause catalyst poisoning on the catalyst surface, preventing the performance of the catalyst from deteriorating, or preventing the catalysis of catalytically active sites. It is preferable that the catalyst further carries a metal other than ruthenium and / or a metal compound other than the ruthenium compound on the carrier containing titanium oxide.

Examples of metals other than ruthenium include silicon, zirconium, aluminum, niobium, tin, copper, iron, cobalt, nickel, vanadium, chromium, molybdenum, and tungsten. Examples of the metal compound other than the ruthenium compound include compounds having a metal other than the ruthenium, and an oxide of the metal other than the ruthenium is preferable. The metal oxide may be a composite oxide of a plurality of metal species. Further, the catalyst may be a catalyst in which an alloy of ruthenium and a metal other than ruthenium or a composite oxide containing ruthenium and a metal other than ruthenium is further supported on the carrier.
More preferably, the catalyst further carries at least one oxide selected from the group consisting of silicon oxide, zirconium oxide, aluminum oxide, niobium oxide and tin oxide on a carrier containing rutile crystalline titanium oxide. It is a catalyst.

The metal salt used to obtain the oxide of the metal is not particularly limited.

Examples of the shape of the catalyst include spherical granules, cylindrical pellets, ring shapes, honeycomb shapes, monolithic shapes, corrugated shapes, granules of appropriate size pulverized and classified after molding, fine particles, and the like. In the case of spherical granules, cylindrical pellets, and ring shape, the catalyst diameter is preferably 10 mm or less from the viewpoint of catalytic activity. The catalyst diameter referred to here means the diameter of a sphere for spherical granules, the diameter of a cross section for a cylindrical pellet, and the maximum diameter of a cross section for other shapes. In the case of a honeycomb shape, a monolith shape, or a corrugated shape, the opening diameter is usually preferably 20 mm or less.

The catalyst used in the method for oxidizing ammonia according to the present invention is, for example, a solution containing ruthenium and / or a ruthenium compound impregnated with a carrier containing ruthenium crystalline titanium oxide, and the carrier is impregnated with ruthenium and / or. It can be prepared by a method of attaching a ruthenium compound and then drying it. The solvent in the solution containing ruthenium and / or the ruthenium compound is not particularly limited, but water, ethanol, or the like can be used. After drying, it may be fired.
When the catalyst contains ruthenium oxide, a step of impregnating a solution containing ruthenium halide with a carrier containing rutyl crystalline titanium oxide to support the carrier with ruthenium halide, and ruthenium halide being used as a carrier. It can be obtained by a method having a step of drying the supported carrier and a step of firing the dried product.

The catalyst can be diluted with an inert substance before use.

The catalyst used in the method for oxidizing ammonia according to the present invention may be heat-treated before use. The heat treatment temperature is not particularly limited, but is usually 100 ° C. to 500 ° C. Further, the heat treatment can be performed in an inert gas such as nitrogen, argon or helium, in air, or in a gas containing carbon monoxide or hydrogen.

[Ammonia oxidation method]
The method for oxidizing ammonia according to the present invention is a method including a step of oxidizing ammonia in an ammonia-containing gas into nitrogen and water in the presence of the catalyst. The oxidation reaction formula of ammonia is as follows.
NH ₃ + 3/4O ₂ → 1 / 2N ₂ + 3 / 2H ₂ O

The step of oxidizing ammonia to nitrogen and water is preferably carried out by bringing an ammonia-containing gas containing oxygen into contact with the catalyst.

The reaction temperature in the method for oxidizing ammonia according to the present invention is preferably 100 ° C. or higher and 500 ° C. or lower, more preferably 120 ° C. or higher and 400 ° C. or lower, and further preferably 120 ° C. or higher and 350 ° C. or lower. The reaction temperature is preferably 500 ° C. or lower from the viewpoint of deterioration of catalytic activity, and preferably 100 ° C. or higher from the viewpoint of reaction rate.
The reaction pressure is preferably 0.005 MPa or more and 1 MPa or less, and more preferably 0.005 MPa or more and 0.5 MPa or less.
Examples of the reaction type in the method for oxidizing ammonia according to the present invention include a fixed bed type and a fluidized bed type.

<Ammonia-containing gas>
The ammonia-containing gas may contain a gas other than ammonia. Examples of gases other than ammonia include oxygen, water vapor, helium, argon, nitrogen, and carbon dioxide. The ammonia-containing gas may contain a liquid.
The ammonia concentration in the ammonia-containing gas is preferably 30% or less.
When the ammonia-containing gas further contains oxygen, the amount of oxygen in the gas is preferably 0.5 to 20 times the amount of ammonia in the gas.
The oxygen-containing ammonia-containing gas can be obtained, for example, by mixing an ammonia-containing gas and an oxygen-containing gas. Examples of the oxygen-containing gas include air.
The supply speed of the ammonia-containing gas containing oxygen is preferably 10h ^-1 or more and 500,000h ^-1 or less, and more preferably 100h ^-1 or more and 50,000h ^-1 or less as the space speed GHSV (h ^-1 ).

[Ammonia-containing gas oxidizing device]
The method for oxidizing ammonia according to the present invention can be carried out using an ammonia-containing gas oxidizing apparatus equipped with the catalyst. The ammonia-containing gas oxidizing apparatus includes a gas introducing means for introducing an ammonia-containing gas and an oxygen-containing gas, or an ammonia-containing gas containing oxygen into the ammonia-containing gas oxidizing apparatus.
As one aspect of the method for oxidizing ammonia according to the present invention, a step of introducing an ammonia-containing gas containing oxygen into an ammonia-containing gas oxidizing apparatus from a gas introducing means, and a step of introducing ammonia in the gas in the presence of the catalyst. Examples thereof include a method having a step of oxidizing to nitrogen and water.

[Ammonia-containing aqueous solution treatment device]
Ammonia in the ammonia-containing aqueous solution is oxidized to nitrogen and water by a dispersal tower having a dissipating means for dissipating the ammonia-containing gas from the ammonia-containing aqueous solution and a treatment device for the ammonia-containing aqueous solution provided with the ammonia-containing gas oxidizing device. can do.
As one aspect of the method for oxidizing ammonia according to the present invention, a step of dissipating the ammonia-containing gas from the ammonia-containing aqueous solution by a dissipating means for dissipating the ammonia-containing gas from the ammonia-containing aqueous solution, and an ammonia-containing gas obtained by the above steps. , The step of introducing the oxygen-containing gas into the ammonia-containing gas oxidizing device by the gas introducing means of the ammonia-containing gas oxidizing device, and in the presence of the catalyst, the ammonia in the ammonia-containing gas oxidizing device is oxidized to nitrogen. And a method having a step of making water.
Examples of the method of dissipating the ammonia-containing gas from the ammonia-containing aqueous solution include a method of contacting the ammonia-containing aqueous solution with a gas and dissipating the ammonia in the ammonia-containing aqueous solution to the gas to obtain the ammonia-containing gas. The gas may contain oxygen, and examples of the gas include air.

Hereinafter, examples of the present invention will be shown, but the present invention is not limited thereto. The space velocity GHSV (h ^-1 ) was calculated by dividing the supply rate (ml / h) of the gas containing ammonia and oxygen by the volume (ml) of the catalyst. Ammonia was analyzed by analyzing the ammonium ion concentration of the water trap attached to the latter stage of the catalyst layer with the ammonia ion electrode. The analysis of NO and NO ₂ was performed by analyzing the gas in the latter stage of the catalyst layer with a detector tube. Analysis of oxygen, nitrogen and _N2O was performed by gas chromatography. The ammonia conversion rate was calculated by the following formula, where the amount of substance (mol) of the supplied ammonia was X and the amount of substance (mol) of unreacted ammonia was Y.
Ammonia conversion rate (%) = [(XY) / X] × 100
The NO, NO ₂ , and N ₂ O production rates were calculated by the following formulas, respectively.
NO generation rate (%): (outlet NO concentration) / (inlet NH ₃ concentration) x 100
NO ₂ generation rate (%): (outlet NO ₂ concentration) / (inlet NH ₃ concentration) x 100
N ₂ O generation rate (%): (outlet N ₂ O concentration) / (inlet NH ₃ concentration) × 100
The activity per 1 g of ruthenium was calculated as a value obtained by dividing the reaction amount of ammonia by the mass (g) of Ru.

<Example 1>
(A) Production of Ammonia Oxidation Catalyst (A) Rutyl Crystal Form Titanium Dioxide [manufactured by Sakai Chemical Industry Co., Ltd., STR-60R, 100% Rutile Crystal Form] 50 parts by weight and α-alumina [manufactured by Sumitomo Chemical Co., Ltd., AES -12] 50 parts by weight is mixed, and then titanium dioxide sol [manufactured by Sakai Chemical Industry Co., Ltd., CSB, titanium dioxide content in titanium dioxide sol is 39% by weight, titanium dioxide is 100% anatase, based on 100 parts by weight of this mixture. Crystal form] 12.8 parts by weight was diluted with pure water and kneaded. This kneaded product was extruded into a cylinder having a diameter of 1.5 mm, dried, and then crushed to a length of about 2 to 4 mm. The obtained molded product was calcined in air at 650 to 680 ° C. for 3 hours to obtain a carrier composed of a mixture of titanium dioxide and α-alumina. This carrier is impregnated with a commercially available aqueous solution of ruthenium chloride hydrate, dried, and then calcined in air at 250 ° C. for 2 hours so that ruthenium oxide is supported on the carrier with a loading ratio of 4% by weight. The ammonia oxidation catalyst (A) was obtained.

(B) Ammonia Oxidation Decomposition The above ammonia oxidation catalyst (A) 0.84 g and SiC 2.00 g are filled in a quartz glass reaction tube having an inner diameter of 1 cm to form a catalyst layer, and 200 ° C. under a helium 62 ml / min flow. After the temperature was raised to 2 ml / min, ammonia 2 ml / min, oxygen 16 ml / min, water 20 ml / min, and helium 62 ml / min were supplied to the reaction tube to carry out the reaction. Thirty minutes after the start of the reaction, the gas in the latter stage of the catalyst layer was sampled, and NO and NO ₂ were analyzed with a detector tube. As a result, the NO production rate was 0.4% and the NO ₂ production rate was 0.2%. _Two hours after the start of the reaction, the gas at the outlet of the catalyst layer was collected and analyzed by gas chromatography. As a result, the N2O production rate was 3.3%. From 2 hours after the start of the reaction to 3 hours after the start of the reaction, the outlet of the catalyst layer was connected to a water trap to absorb unreacted ammonia. When the above water trap was analyzed with an ammonia ion electrode, the ammonia conversion rate was 95.7%.

<Example 2>
(A) Production of Titanium Dioxide Powder (B) Titanium Dioxide Powder [Showa Titanium Co., Ltd., F-1R, Rutile Crystalline Titanium Dioxide Ratio 93%] 100 parts by weight and 2 parts by weight of organic binder [Yuken Kogyo Co., Ltd., YB-152A] is mixed, then 29 parts by weight of pure water, titanium dioxide sol [manufactured by Sakai Chemical Industry Co., Ltd., CSB, titanium dioxide content in titanium dioxide sol 40% by weight, 100% anatase crystal form] 12.5 weight The portion was added and kneaded. This mixture was extruded into a noodle shape having a diameter of 3.0 mm, dried at 60 ° C. for 2 hours, and then crushed to a length of about 3 to 5 mm. The obtained molded product was heated in air from room temperature to 600 ° C. for 1.7 hours, held at 600 ° C. for 3 hours, and then calcined to obtain a white titanium dioxide carrier [rutile crystalline titanium dioxide ratio 90. % Or more] was obtained.
60.0 g of the titanium dioxide carrier obtained above was placed in a 200 mL eggplant-shaped flask, set in a rotary impregnation-drying device, and the eggplant-shaped flask was tilted 60 degrees from the vertical direction and rotated at 80 rpm. , Tetraethoxysilane [manufactured by Wako Pure Chemical Industries, Ltd., Si (OC ₂ H ₅ ) ₄ ] 2.13 g of ethanol is dissolved in 9.22 g of ethanol, and a solution prepared is dropped into the eggplant-shaped flask in 20 minutes. The solution was impregnated into the titanium dioxide carrier. Next, the temperature inside the eggplant-shaped flask was set to 30 ° C. while stirring the titanium dioxide carrier by rotating the eggplant-shaped flask containing the impregnated titanium dioxide carrier at 80 rpm, and steam and nitrogen were added to the eggplant-shaped flask. Titanium dioxide after impregnation by continuously supplying the mixed gas (water vapor concentration: 2.0% by volume) at a flow rate of 277 mL / min (0 ° C, 0.1 MPa conversion) for 4 hours and 20 minutes and circulating it. The carrier was dried. 62.3 g of the obtained dried product was heated from room temperature to 300 ° C. for 1.2 hours under air flow, held at the same temperature for 2 hours and fired, and silicon dioxide was supported on a titanium dioxide carrier. 60.6 g of a solid (silicon dioxide-supported titanium dioxide carrier) was obtained. 30.1 g of the obtained silicon dioxide-supported titanium dioxide carrier was placed in a 200 mL eggplant-shaped flask, set in a rotary impregnation-drying device, and the eggplant-shaped flask was tilted 60 degrees from the vertical direction and rotated at 80 rpm. However, an aqueous solution prepared by dissolving 0.71 g of ruthenium chloride hydrate [Furuya Metal Co., Ltd., _{RuCl 3.nH2O} , Ru content 40.75% by weight] in 6.89 g of pure water was prepared as the eggplant type. The aqueous solution was impregnated by dropping into a flask for 30 minutes to obtain 37.70 g of ruthenium chloride carrier. Next, while stirring the ruthenium chloride carrier by rotating the eggplant-shaped flask containing the ruthenium chloride carrier at 80 rpm, the temperature inside the eggplant-shaped flask was set to 35 ° C., and 692 mL of air was introduced into the eggplant-shaped flask. It was continuously supplied at a flow rate of / min (0 ° C., converted to 0.1 MPa) for 3 hours and 40 minutes, and dried by circulating to obtain 32.21 g of dried product A. 32.21 g of the obtained dried product A was placed in a closed container and kept at 20 ° C. for 120 hours in a constant temperature bath. The weight of the dried product A after holding was 32.21 g. The amount of water based on the weight of the silicon dioxide-supported titanium dioxide carrier contained in the dried product A after holding did not change from that before holding, and the amount of water evaporated was 0 g. 21.48 g of the dried product A after holding was heated from room temperature to 280 ° C. for 1.2 hours under air flow, and then held at the same temperature for 2 hours and fired to increase the content of ruthenium oxide. 20.34 g of a blue-gray ammonia oxidation catalyst (B) (ruthenium oxide and silicon dioxide supported on titanium dioxide) was obtained in an amount of 1.25% by weight.

(B) Ammonia Oxidation Decomposition The same procedure as in Example 1 was carried out except that the above ammonia oxidation catalyst (B) was used. As a result, the ammonia conversion rate was 55.6%, the NO production rate was 0.08%, the NO ₂ production rate was 0.02%, and the _N2O production rate was 0.98%.

<Reference example 1>
(A) Production of Ammonia Oxidation Catalyst (C) For 10 g of titanium dioxide in the form of anatase crystal shaped into a sphere of 1 to 2 mm [manufactured by Sakai Chemical Industry Co., Ltd., CS-300S-12, 100% anatase crystal form] , 0.77 g of ruthenium chloride hydrate and 3.25 g of water were added dropwise. The obtained mixture is air-dried for 18 hours and then calcined at 250 ° C. for 2 hours in a tubular furnace under 200 ml / min air flow to support an ammonia oxidation catalyst in which ruthenium oxide is supported on the carrier at a loading ratio of 4% by weight. (C) was obtained.

(B) Ammonia Oxidation Decomposition The reaction was carried out in the same manner as in Example 1 except that the above ammonia oxidation catalyst (C) was used. As a result, the ammonia conversion rate was 19.7%, the NO production rate was 0.02%, the NO ₂ production rate was 0.0%, and the _N2O production rate was 0.0%.

Claims (8)

Ruthenium oxide is supported on a carrier containing rutile crystalline titanium oxide, and ruthenium oxide is 100% by weight, with the total content of ruthenium oxide and the carrier containing rutile crystalline titanium oxide being 100% by weight. In the presence of a catalyst whose content is 0.5-10% by weight based on metallic ruthenium .
The step of oxidizing the ammonia in the ammonia-containing gas to nitrogen and water is included, the ammonia-containing gas contains oxygen, and the amount of oxygen in the ammonia-containing gas is 0.5 times or more the amount of ammonia . ,
The supply speed (space speed) of the ammonia-containing gas in the step of oxidizing the ammonia in the ammonia-containing gas to nitrogen and water is 10h ^-1 to 500,000h ^-1 , the reaction temperature is 100 ° C to 500 ° C, and the reaction occurs. A method for oxidizing ammonia, wherein the pressure is 0.005 MPa to 1 MPa . The method for oxidizing ammonia according to claim 1, wherein the amount of oxygen in the ammonia-containing gas is 0.5 to 20 times the amount of ammonia. The method for oxidizing ammonia according to claim 1 or 2, wherein the ammonia concentration in the ammonia-containing gas is 30% or less. The method for oxidizing ammonia according to any one of claims 1 to 3, wherein the reaction temperature in the step of oxidizing ammonia to nitrogen and water is 120 ° C to 350 ° C. The method for oxidizing ammonia according to any one of claims 1 to 4, wherein the step of oxidizing ammonia to nitrogen and water is performed by bringing the ammonia-containing gas into contact with the catalyst. The catalyst is any one of claims 1 to 5 , wherein the catalyst is a catalyst in which at least one oxide selected from the group consisting of silicon oxide, zirconium oxide, aluminum oxide, niobium oxide and tin oxide is further supported on the carrier. The method for oxidizing aluminum according to the section. Ruthenium oxide is supported on a carrier containing rutile crystalline titanium oxide, and ruthenium oxide is 100% by weight, with the total content of ruthenium oxide and the carrier containing rutile crystalline titanium oxide being 100% by weight. A catalyst-filled reactor in which the content of rutile is 0.5 to 10% by weight based on metal rutile , and
It is equipped with a gas introducing means for introducing an ammonia-containing gas and an oxygen-containing gas, or an oxygen-containing ammonia-containing gas into a reactor.
An ammonia-containing gas oxidizing apparatus for carrying out the method for oxidizing ammonia according to any one of claims 1 to 6 . A device for treating an ammonia-containing aqueous solution, comprising a dissipating tower having a dissipating means for dissipating the ammonia-containing gas from the ammonia-containing aqueous solution, and the ammonia-containing gas oxidizing device according to claim 7 .