A multi-metal oxide catalyst for catalytic ozonation of ammonia nitrogen and a preparation method thereof

Abstract

The application discloses a multi-metal oxide catalyst for catalyzing ozone oxidation of ammonia nitrogen, and belongs to the technical field of wastewater treatment catalysis. The multi-metal oxide is uniformly dispersed in the catalyst, and the oxides formed after calcination and decomposition of the precipitated salt do not form solid solution compounds. The multi-oxide catalyst comprises the following components: Al2O3 with a mass content of 42% to 54%; NiO with a mass content of 18% to 26%; CuO with a mass content of 22% to 38%; and MnO2 with a mass content of 23% to 32%. Under the condition that 10 to 15 ml / min of ozone is introduced, the ammonia nitrogen concentration of wastewater is 230 mg / L, and the removal rate of ammonia nitrogen and chlorine reaches 23.9%. The catalyst preparation process is simple, and the catalyst does not cause secondary environmental pollution after oxidizing ammonia nitrogen.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology for environmental protection and controlling ammonia nitrogen concentration in industrial wastewater, specifically to a multi-metal oxide catalytic ozone treatment catalyst for ammonia nitrogen and its preparation method, belonging to the field of catalyst preparation technology. Background Technology

[0002] With the development of industries such as chemical and electroplating, increasing amounts of ammonia nitrogen are being discharged into rivers and lakes, leading to eutrophication, promoting algal blooms, causing fish and other aquatic organisms to die from oxygen depletion, reducing water quality, and damaging biodiversity. High-concentration ammonia nitrogen wastewater has poor biodegradability, low carbon and nitrogen values, and is difficult to treat. Furthermore, the large-scale algal blooms may threaten human health.

[0003] Currently, industrial treatment of ammonia nitrogen in wastewater is divided into physical stripping and membrane separation. Stripping involves adjusting the solution pH to alkaline and then blowing in air to expel free ammonia. While convenient, the released ammonia gas can cause secondary pollution. Membrane separation uses a special semi-permeable membrane to separate the solute and solvent in the solution. Its advantages include simple operation and high stability, but disadvantages include high cost and susceptibility to membrane clogging by suspended solids.

[0004] Chemical methods include breakpoint chlorination, ion exchange, and chemical precipitation. Breakpoint chlorination requires the addition of large amounts of chlorine, producing byproducts such as chloramine and chlorinated organic compounds, which can easily cause secondary pollution. Ion exchange generally uses zeolite as the ion exchange resin; however, prolonged use can cause suspended solids to clog the zeolite channels, reducing exchange efficiency. Chemical precipitation involves adding phosphoric acid or hydrogen phosphate to generate magnesium ammonium phosphate precipitate, achieving the goal of reducing ammonia nitrogen. Its disadvantage is the introduction of new impurities, phosphate, which can also cause secondary pollution. Summary of the Invention

[0005] Given the shortcomings of the above methods in the process, or the fact that they may cause secondary pollution to the environment to varying degrees, the purpose of this invention is to provide a catalyst for the ozone treatment of ammonia nitrogen by catalysis of polymetallic oxides. The preparation method is simple, the raw materials are readily available, and the catalyst after molding has high strength, stable structure, high ammonia nitrogen conversion rate, and will not cause secondary pollution.

[0006] This invention provides the following technical solution: a multi-metal oxide catalytic ozone oxidation catalyst for ammonia nitrogen, characterized in that the catalyst is a catalyst in which one of two oxides, Al2O3, NiO, CuO or MnO2, is uniformly distributed, and the composition of the catalyst is Al2O3 with a mass content of 42%-54%; NiO with a mass content of 18%-26%; CuO with a mass content of 22%-38% or MnO2 with a mass content of 23%-32%.

[0007] The method for preparing the catalyst provided by the present invention is characterized in that the cation of the oxide is a nitrate, and a uniformly distributed cation is obtained by co-precipitation.

[0008] The catalyst prepared by the method of the present invention has a uniform dispersion of polymetallic oxides, and the oxides formed after the calcination and decomposition of the precipitated salt do not form solid solution compounds.

[0009] Generally, the catalyst is prepared as follows: aluminum nitrate, nickel nitrate, copper nitrate or manganese nitrate are taken, and deionized water is added to prepare a homogeneous solution; sodium carbonate is added dropwise to the solution while stirring continuously to form a homogeneous precipitate; after the reaction is complete, nitric acid is added dropwise to adjust the pH of the slurry, and stirring is continued until the pH value stabilizes, and the precipitate is aged; the precipitate solution is filtered and washed to form a filter cake; the filter cake is dried and shaped; the shaped particles are calcined under a nitrogen atmosphere to form a homogeneous multi-metal oxide catalyst.

[0010] Preferably, the solution is stirred in a water bath at 50-60°C, and sodium carbonate is added dropwise while stirring continuously to form a homogeneous precipitate.

[0011] Preferably, after the reaction is complete, the pH of the slurry is adjusted to 6.5-7 by adding nitric acid with a concentration of 0.1mol / L to 0.5mol / L, and stirring is continued until the pH value stabilizes, followed by aging and sedimentation for 4-6 hours.

[0012] Preferably, the precipitate solution is filtered, washed with deionized water until five drops of diphenylamine sulfuric acid solution are added, filtered, and precipitated to form a filter cake.

[0013] Preferably, the filter cake is dried in an oven at 120°C for 5-6 hours, then shaped into sheets.

[0014] Preferably, the shaped particles are heated to 450-480°C in a muffle furnace under a nitrogen atmosphere and calcined for 4-6 hours to form a uniformly distributed multi-metal oxide catalyst.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. The multi-metal oxide catalytic ozone oxidation catalyst prepared by this invention has uniformly dispersed metal oxides, and the catalyst exhibits high strength and stable structure after molding;

[0017] 2. The catalyst has a wide range of applicable conditions, is safe and environmentally friendly, and will not cause secondary pollution to the environment;

[0018] 3. Raw materials are readily available, the preparation process is simple and efficient, it occupies little space, and production capacity is not affected. Detailed Implementation

[0019] To further illustrate the present invention, the following detailed description of the "Preparation of a Multimetal Oxide Catalyst for Ozone Oxidation of Ammonia Nitrogen" provided by the present invention is provided in conjunction with the embodiments, but the present invention is not limited thereto.

[0020] Example 1

[0021] (1) According to the target product, weigh 291.2g of aluminum nitrate nonahydrate, 77.6g of nickel nitrate hexahydrate and 112.2g of copper nitrate trihydrate, place them in a beaker and add deionized water to 800ml.

[0022] (2) Place the beaker in a 50℃ water bath and heat and stir continuously until all the solutes are completely dissolved. Add sodium carbonate solution to neutralize the solution using a peristaltic pump at a rate of 20 ml / min while stirring until the solution pH is 8.0. Continue stirring for 30 min, then add 0.1 mol / L nitric acid to adjust the solution pH to 7.0. Allow the precipitate to age for 4 h.

[0023] (3) The precipitate solution is filtered, stirred with deionized water, and washed until five drops of diphenylamine sulfuric acid solution are not blue, and a filter cake is formed. The filter cake is placed in an oven and dried at 120°C for 5 hours. After drying, it is crushed and shaped into sheets.

[0024] (4) The catalyst particles are formed by heating the muffle furnace to 200°C at 10°C / min under a nitrogen atmosphere, holding for 30 minutes, then heating to 450°C at 5°C / min, holding for 4 hours, and then cooling naturally to form a uniform multi-metal oxide catalyst.

[0025] Take 100 ml of the above catalyst and place it in a reaction flask. Add 500 ml of wastewater with an ammonia nitrogen concentration of 220 mg / L and simultaneously bubble in ozone at a rate of 10 ml / min. Continue the reaction for 30 min and measure the ammonia nitrogen concentration of the solution after the reaction.

[0026] Example 2

[0027] (1) According to the target product, weigh 397.3g of aluminum nitrate nonahydrate, 69.8g of nickel nitrate hexahydrate and 82.6g of copper nitrate trihydrate, place them in a beaker and add deionized water to 800ml.

[0028] (2) Place the beaker in a 60℃ water bath and heat and stir continuously until all the solutes are completely dissolved. Add sodium carbonate solution to neutralize the solution using a peristaltic pump at a rate of 20 ml / min while stirring until the solution pH is 8.0. Continue stirring for 30 min, then add 0.5 mol / L nitric acid to adjust the solution pH to 6.4. Allow the precipitate to age for 6 h.

[0029] (3) The precipitate solution is filtered, stirred with deionized water, and washed until five drops of diphenylamine sulfuric acid solution are not blue, and a filter cake is formed. The filter cake is placed in an oven and dried at 120°C for 6 hours. After drying, it is crushed and shaped into sheets.

[0030] (4) The catalyst particles are formed by heating the muffle furnace to 200°C at 10°C / min under a nitrogen atmosphere, holding for 30 minutes, then heating to 450°C at 5°C / min, holding for 6 hours, and then cooling naturally to form a uniform multi-metal oxide catalyst.

[0031] Take 100 ml of the above catalyst and place it in a reaction flask. Add 500 ml of wastewater with an ammonia nitrogen concentration of 230 mg / L and simultaneously bubble in ozone at a rate of 10 ml / min. Continue the reaction for 40 min and measure the ammonia nitrogen concentration of the solution after the reaction.

[0032] Example 3

[0033] (1) According to the target product, weigh 382.3g of aluminum nitrate nonahydrate, 100.9g of nickel nitrate hexahydrate and 64.9g of copper nitrate trihydrate, place them in a beaker and add deionized water to 800ml.

[0034] (2) Place the beaker in a 60℃ water bath and heat and stir continuously until all the solutes are completely dissolved. Add sodium carbonate solution to neutralize the solution using a peristaltic pump at a rate of 20 ml / min while stirring until the solution pH is 8.0. Continue stirring for 30 min, then add 0.1 mol / L nitric acid to adjust the solution pH to 6.8. Allow the precipitate to age for 5 h.

[0035] (3) The precipitate solution is filtered, stirred with deionized water, and washed until five drops of diphenylamine sulfuric acid solution are not blue, and a filter cake is formed. The filter cake is placed in an oven and dried at 120°C for 6 hours. After drying, it is crushed and shaped into sheets.

[0036] (4) The catalyst particles are formed by heating the muffle furnace to 200°C at 10°C / min under a nitrogen atmosphere, holding for 30 minutes, then heating to 450°C at 5°C / min, holding for 5 hours, and then cooling naturally to form a uniform multi-metal oxide catalyst.

[0037] Measure 100 ml of the above catalyst and place it in a reaction flask. Add 500 ml of wastewater with an ammonia nitrogen concentration of 230 mg / L and simultaneously bubble ozone in at a rate of 15 ml / min. Continue the reaction for 40 min and measure the ammonia nitrogen concentration of the solution after the reaction.

[0038] Example 4

[0039] (1) According to the target product, weigh 375.1g of aluminum nitrate nonahydrate, 100.8g of nickel nitrate hexahydrate and 66.4g of copper nitrate trihydrate, place them in a beaker and add deionized water to 800ml.

[0040] (2) Place the beaker in a 55℃ water bath and heat and stir continuously until all the solutes are completely dissolved. Add sodium carbonate solution to neutralize the solution using a peristaltic pump at a rate of 20 ml / min while stirring until the solution pH is 8.0. Continue stirring for 30 min, then add 0.5 mol / L nitric acid to adjust the solution pH to 7.0. Allow the precipitate to age for 6 h.

[0041] (3) The precipitate solution is filtered, stirred with deionized water, and washed until five drops of diphenylamine sulfuric acid solution are not blue, and a filter cake is formed. The filter cake is placed in an oven and dried at 120°C for 5 hours. After drying, it is crushed and shaped into sheets.

[0042] (4) The catalyst particles are formed by heating the muffle furnace to 200°C at 10°C / min under a nitrogen atmosphere, holding for 30 minutes, then heating to 450°C at 5°C / min, holding for 5 hours, and then cooling naturally to form a uniform multi-metal oxide catalyst.

[0043] Take 100 ml of the above catalyst and place it in a reaction flask. Add 500 ml of wastewater with an ammonia nitrogen concentration of 220 mg / L and simultaneously bubble in ozone at a rate of 15 ml / min. Continue the reaction for 50 min and then measure the ammonia nitrogen concentration of the solution.

[0044] Example 5

[0045] (1) According to the target product, weigh 382.3g of aluminum nitrate nonahydrate, 100.9g of nickel nitrate hexahydrate and 64.9g of copper nitrate trihydrate, place them in a beaker and add deionized water to 800ml.

[0046] (2) Place the beaker in a 60℃ water bath and heat and stir continuously until all the solutes are completely dissolved. Add sodium carbonate solution to neutralize the solution using a peristaltic pump at a rate of 20 ml / min while stirring until the solution pH is 8.0. Continue stirring for 30 min, then add 0.1 mol / L nitric acid to adjust the solution pH to 6.8. Allow the precipitate to age for 5 h.

[0047] (3) The precipitate solution is filtered, stirred with deionized water, and washed until five drops of diphenylamine sulfuric acid solution are not blue, and a filter cake is formed. The filter cake is placed in an oven and dried at 120°C for 6 hours. After drying, it is crushed and shaped into sheets.

[0048] (4) The catalyst particles are formed by heating the muffle furnace to 200°C at 10°C / min under a nitrogen atmosphere, holding for 30 minutes, then heating to 450°C at 5°C / min, holding for 5 hours, and then cooling naturally to form a uniform multi-metal oxide catalyst.

[0049] Take 100 ml of the above catalyst and place it in a reaction flask. Add 500 ml of wastewater with an ammonia nitrogen concentration of 220 mg / L and simultaneously bubble in ozone at a rate of 10 ml / min. Continue the reaction for 30 min and measure the ammonia nitrogen concentration of the solution after the reaction.

[0050] Example 6

[0051] (1) According to the target product, weigh 352.9g of aluminum nitrate nonahydrate, 77.6g of nickel nitrate hexahydrate and 102.5g of manganese nitrate tetrahydrate, place them in a beaker and add deionized water to 800ml.

[0052] (2) Place the beaker in a 60℃ water bath and heat and stir continuously until all the solutes are completely dissolved. Add sodium carbonate solution to neutralize the solution using a peristaltic pump at a rate of 20 ml / min while stirring until the solution pH is 8.0. Continue stirring for 30 min, then add 0.3 mol / L nitric acid to adjust the solution pH to 7.0. Allow the precipitate to age for 6 h.

[0053] (3) The precipitate solution is filtered, stirred with deionized water, and washed until five drops of diphenylamine sulfuric acid solution are not blue, and a filter cake is formed. The filter cake is placed in an oven and dried at 120°C for 5 hours. After drying, it is crushed and shaped into sheets.

[0054] (4) The catalyst particles are formed by heating the muffle furnace to 200°C at 10°C / min under a nitrogen atmosphere, holding for 30 minutes, then heating to 450°C at 5°C / min, holding for 6 hours, and then cooling naturally to form a uniform multi-metal oxide catalyst.

[0055] Take 100 ml of the above catalyst and place it in a reaction flask. Add 500 ml of wastewater with an ammonia nitrogen concentration of 230 mg / L and simultaneously bubble in ozone at a rate of 10 ml / min. Continue the reaction for 40 min and measure the ammonia nitrogen concentration of the solution after the reaction.

[0056] Example 7

[0057] (1) According to the target product, weigh 291.3g of aluminum nitrate nonahydrate, 100.9g of nickel nitrate hexahydrate and 113.2g of manganese nitrate tetrahydrate, place them in a beaker, and add deionized water to 800ml.

[0058] (2) Place the beaker in a 60℃ water bath and heat and stir continuously until all the solutes are completely dissolved. Add sodium carbonate solution to neutralize the solution using a peristaltic pump at a rate of 20 ml / min while stirring until the solution pH is 8.0. Continue stirring for 30 min, then add 0.1 mol / L nitric acid to adjust the solution pH to 6.8. Allow the precipitate to age for 5 h.

[0059] (3) The precipitate solution is filtered, stirred with deionized water, and washed until five drops of diphenylamine sulfuric acid solution are not blue, and a filter cake is formed. The filter cake is placed in an oven and dried at 120°C for 6 hours. After drying, it is crushed and shaped into sheets.

[0060] (4) The catalyst particles are formed by heating the muffle furnace to 200°C at 10°C / min under a nitrogen atmosphere, holding for 30 minutes, then heating to 450°C at 5°C / min, holding for 5 hours, and then cooling naturally to form a uniform multi-metal oxide catalyst.

[0061] Measure 100 ml of the above catalyst and place it in a reaction flask. Add 500 ml of wastewater with an ammonia nitrogen concentration of 230 mg / L and simultaneously bubble ozone in at a rate of 15 ml / min. Continue the reaction for 40 min and measure the ammonia nitrogen concentration of the solution after the reaction.

[0062] Example 8

[0063] (1) According to the target product, weigh 397.2g of aluminum nitrate nonahydrate, 89.2g of nickel nitrate hexahydrate and 72.5g of manganese nitrate tetrahydrate, place them in a beaker, and add deionized water to 800ml.

[0064] (2) Place the beaker in a 60℃ water bath and heat and stir continuously until all the solutes are completely dissolved. Add sodium carbonate solution to neutralize the solution using a peristaltic pump at a rate of 20 ml / min while stirring until the solution pH is 8.0. Continue stirring for 30 min, then add 0.1 mol / L nitric acid to adjust the solution pH to 6.8. Allow the precipitate to age for 5 h.

[0065] (3) The precipitate solution is filtered, stirred with deionized water, and washed until five drops of diphenylamine sulfuric acid solution are not blue, and a filter cake is formed. The filter cake is placed in an oven and dried at 120°C for 6 hours. After drying, it is crushed and shaped into sheets.

[0066] (4) The catalyst particles are formed by heating the muffle furnace to 200°C at 10°C / min under a nitrogen atmosphere, holding for 30 minutes, then heating to 450°C at 5°C / min, holding for 5 hours, and then cooling naturally to form a uniform multi-metal oxide catalyst.

[0067] Take 100 ml of the above catalyst and place it in a reaction flask. Add 500 ml of wastewater with an ammonia nitrogen concentration of 220 mg / L and simultaneously bubble in ozone at a rate of 15 ml / min. Continue the reaction for 50 min and then measure the ammonia nitrogen concentration of the solution.

[0068] Ammonia nitrogen conversion rate table

[0069] Example Ammonia nitrogen in raw wastewater (mg / L) Ammonia nitrogen after treatment (mg / L) Conversion rate (%) Example 1 220 142 35.5 Example 2 230 146 36.5 Example 3 230 148 35.6 Example 4 220 132 40.1 Example 5 220 140 36.4 Example 6 230 141 38.7 Example 7 230 139 39.6 Example 8 220 128 41.8

Claims

1. A polymetallic oxide catalytic catalyst for ozone oxidation of ammonia nitrogen, characterized in that... The catalyst is a uniformly distributed catalyst composed of one of two oxides: Al2O3, NiO, CuO, or MnO2. The composition of Al2O3 is 42%-54% by mass; NiO is 18%-26% by mass; CuO is 22%-38% by mass; or MnO2 is 23%-32% by mass. The catalyst is prepared as follows: aluminum nitrate, nickel nitrate, copper nitrate, or manganese nitrate are added to deionized water to prepare a homogeneous solution. The solution is stirred in a water bath at 50-60℃, and sodium carbonate is added dropwise with continuous stirring to form a homogeneous precipitate. After the reaction is complete, the pH of the slurry is adjusted to 6.5-7 by adding 0.1mol / L to 0.5mol / L nitric acid, and stirring is continued until the pH value stabilizes. The precipitate is aged for 4-6 hours. The precipitate solution is filtered and washed to form a filter cake. The filter cake is dried and shaped. The shaped particles are calcined in a muffle furnace under a nitrogen atmosphere at a programmed temperature of 450-480℃ for 4-6 hours to form a uniformly distributed multi-metal oxide catalyst.

2. The catalyst as described in claim 1, characterized in that... The prepared catalyst contains uniformly dispersed polymetallic oxides, and the oxides formed after the calcination and decomposition of the precipitated salt do not form solid solution compounds.

3. The catalyst as described in claim 1, characterized in that... The precipitate solution was filtered, washed with deionized water until five drops of diphenylamine sulfuric acid solution were added, filtered, and precipitated to form a filter cake.

4. The catalyst as described in claim 1, characterized in that... Dry the filter cake at 120℃ in an oven for 5-6 hours, then shape it into sheets.