Method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater

Abstract

The application relates to the technical field of wastewater treatment, and discloses a catalytic oxidation treatment method for unsymmetrical dimethylhydrazine wastewater, which comprises the following steps: feeding unsymmetrical dimethylhydrazine wastewater into a primary reactor, catalytically oxidizing the unsymmetrical dimethylhydrazine wastewater by using a transition metal oxide catalyst or / and a noble metal oxide catalyst, and heating the primary reactor by using microwaves; feeding intermediate products generated in the primary reactor into a secondary reactor, catalytically oxidizing the intermediate products by using a transition metal oxide catalyst or / and a noble metal oxide catalyst; and discharging exhaust gas generated in the secondary reactor after treatment. The application uses microwave technology for heating, utilizes the energy transmission characteristics of strong microwave penetration and selective heating, can reduce the bond energy of polar molecules of unsymmetrical dimethylhydrazine, and makes the polar molecules easy to break. Meanwhile, the transition metal oxide catalyst or / and the noble metal oxide catalyst can be activated by microwave quantum effect, the degradation reaction activation energy is reduced, the reaction rate of the degradation process is effectively improved, and the treatment effect of the unsymmetrical dimethylhydrazine wastewater is improved.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and in particular to a method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater. Background Technology

[0002] Unsymmetrical dimethylhydrazine (UDMH) wastewater refers to leaks and drips from storage tanks and pipelines of UDMH storage facilities, as well as washing liquids from cleaning and maintenance of storage tanks and pipelines, or UDMH wastewater generated during the combustion of UDMH and cooling water during rocket and missile launches. Due to the high toxicity of UDMH, related industries have high requirements for the treatment of UDMH wastewater.

[0003] Currently, common treatment methods for unsymmetrical dimethylhydrazine (UDMH) wastewater include catalytic oxidation, wet oxidation, and photocatalysis. However, the treatment effect of high-concentration UDMH wastewater using existing technologies remains poor, hindering the development of related industries. Summary of the Invention

[0004] The main purpose of this application is to provide a catalytic oxidation treatment method for unsymmetrical dimethylhydrazine (UDMH) wastewater, which aims to solve the technical problems of poor treatment effect and inability to meet emission standards for high-concentration UDMH wastewater.

[0005] To achieve the above objectives, this application proposes a method for the catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater, comprising the following steps:

[0006] Unsymmetrical dimethylhydrazine (UDMH) wastewater is fed into a primary reactor, where transition metal oxide catalysts and / or noble metal oxide catalysts are used to catalytically oxidize the UDMH wastewater. The primary reactor is heated by microwave.

[0007] The intermediate product generated in the primary reactor is fed into the secondary reactor, where the intermediate product is catalytically oxidized using a transition metal oxide catalyst and / or a noble metal oxide catalyst. The secondary reactor is heated by microwave or electric heating.

[0008] The wastewater treated in the secondary reactor is discharged after passing the test. At the same time, the exhaust gas generated in the primary and secondary reactors is treated before being discharged.

[0009] Optionally, the following steps are also included:

[0010] When the catalytic activity of transition metal oxide catalysts and / or noble metal oxide catalysts decreases to the threshold, the feed of unsymmetrical dimethylhydrazine wastewater is stopped, and catalyst regeneration gas is introduced to regenerate the transition metal oxide catalysts and / or noble metal oxide catalysts with reduced reactivity.

[0011] The catalyst regeneration gas contains oxygen (which may be air).

[0012] Optionally, the reaction temperature for regenerating the transition metal oxide catalyst and / or noble metal oxide catalyst is 320-370℃, the time is 50-70 min, and the catalyst regeneration efficiency is ≥90%.

[0013] Optionally, the transition metal oxide catalyst includes at least one of titanium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, and copper oxide.

[0014] Optionally, the treatment of the exhaust gas includes the following steps:

[0015] The exhaust gas is filtered by a filter, monitored by an online monitoring instrument, cooled by a heat exchanger, and then discharged.

[0016] Optionally, the temperature for catalytic oxidation of unsymmetrical dimethylhydrazine wastewater is 85-95℃.

[0017] Optionally, the feed flow rate of the unsymmetrical dimethylhydrazine wastewater is 1.8-2.2 kg / h, and the loading amount of transition metal oxide catalyst and / or noble metal oxide catalyst is 110-130 kg.

[0018] Optionally, the reaction temperature for catalytic oxidation of the intermediate product is 80-120°C.

[0019] Optionally, the primary reactor and / or the secondary reactor are packed tower reactors.

[0020] Optionally, the concentration of unsymmetrical dimethylhydrazine in the wastewater is 800-1800 mg / L, and the water quality indicators of the treated wastewater meet the requirements of GB14374-1993, namely: unsymmetrical dimethylhydrazine ≤0.5 mg / L, formaldehyde ≤1 mg / L, ammonia nitrogen ≤40 mg / L, and CODcr ≤100 mg / L.

[0021] Compared with the prior art, the beneficial effects achieved by this application are as follows:

[0022] This application utilizes a two-stage reactor to catalytically oxidize unsymmetrical dimethylhydrazine (UDMH) at relatively low temperatures, rendering it inorganic to produce carbon dioxide, water, and nitrogen. Typically, high-concentration UDMH wastewater contains approximately 800-1800 mg / L of UDMH, making complete degradation difficult with conventional electric heating methods. This application employs microwave technology for heating, leveraging the strong penetrability and selective heating energy transfer characteristics of microwaves to reduce the bond energy of the polar chemical bonds in UDMH molecules, making them easier to break and accelerating the degradation process. Simultaneously, the catalyst used is a transition metal oxide catalyst and / or noble metal oxide catalyst. These catalysts are highly dielectric loss materials, and their catalytic activity is easily activated by microwave quantum effects, lowering the activation energy of the degradation reaction and effectively improving the reaction rate and efficiency of the degradation process, thus enhancing the treatment effect of UDMH wastewater. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the process for the catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater as described in the embodiments of this application;

[0025] Figure 2 This is a schematic diagram of the unsymmetrical dimethylhydrazine wastewater catalytic oxidation treatment system described in the embodiments of this application.

[0026] Symbol explanation: 1-feed tank, 2-first stage reactor, 3-first stage waste liquid buffer tank, 4-first stage exhaust gas online detector, 5-second stage reactor, 6-second stage waste liquid buffer tank, 7-second stage exhaust gas online detector.

[0027] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0028] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. In addition, the meaning of "and / or" in the whole text includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, or solution B, or a solution that satisfies both A and B. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0029] The upper limit of unsymmetrical dimethylhydrazine concentration in high-concentration wastewater is about 800-1800 mg / L. Ordinary electric heating methods are difficult to achieve its complete degradation, resulting in a large number of harmful intermediate products in the treated unsymmetrical dimethylhydrazine wastewater, which cannot meet the discharge standards.

[0030] To address the technical problems existing in the treatment of high-concentration unsymmetrical dimethylhydrazine (UDMH) wastewater, embodiments of this application provide a catalytic oxidation treatment method for UDMH wastewater, comprising the following steps:

[0031] S10. The unsymmetrical dimethylhydrazine wastewater is fed into the primary reactor 2, and the unsymmetrical dimethylhydrazine wastewater is oxidized by transition metal oxide catalyst and / or noble metal oxide catalyst. The primary reactor 2 is heated by microwave.

[0032] S20. The intermediate product generated in the primary reactor 2 is fed into the secondary reactor 5, and the intermediate product is catalytically oxidized using a transition metal oxide catalyst and / or a noble metal oxide catalyst.

[0033] S30. Wastewater treated in the secondary reactor 5 is discharged after passing the test.

[0034] In primary reactor 2, transition metal oxides and / or noble metal oxides oxidize unsymmetrical dimethylhydrazine. The reaction product is an intermediate product composed of carbon dioxide, water, amines, and small organic molecules. This intermediate product needs to be further processed in secondary reactor 5. The specific reactions occurring in primary reactor 2 are as follows:

[0035]

[0036] In secondary reactor 5, transition metal oxides further catalytically oxidize the aforementioned intermediates such as amines and small-molecule organic compounds, producing nitrogen, carbon dioxide, and water as reaction products. The specific reactions occurring in secondary reactor 5 are as follows:

[0037]

[0038]

[0039] This application addresses the treatment of high-concentration unsymmetrical dimethylhydrazine (UDMH) wastewater. Conventional electric heating methods are insufficient for the complete degradation of this wastewater. This application employs microwave technology for heating, utilizing the strong penetrability and selective heating energy transfer characteristics of microwaves to reduce the bond energy of the polar chemical bonds in UDMH molecules, making them easier to break. Simultaneously, the catalyst used is a transition metal oxide catalyst and / or a noble metal oxide catalyst. These catalysts are highly dielectric loss materials, and their catalytic activity is easily activated by the microwave quantum effect, lowering the activation energy of the degradation reaction and effectively increasing the reaction rate and efficiency of the degradation process, thereby improving the treatment effect of UDMH wastewater.

[0040] By using a two-stage reactor connected in series to catalytically oxidize unsymmetrical dimethylhydrazine under low-temperature conditions, it is rendered inorganic to produce nitrogen, carbon dioxide, water, etc., thus achieving the inorganic / harmless treatment of organic waste. This process technology is simple to operate, safe and controllable, and has a wide treatment range.

[0041] As one possible implementation of this application, the processing method further includes the following steps:

[0042] When the catalytic activity of transition metal oxide catalysts and / or noble metal oxide catalysts decreases to the threshold, the feed of unsymmetrical dimethylhydrazine wastewater is stopped, and catalyst regeneration gas is introduced to regenerate the transition metal oxide catalysts and / or noble metal oxide catalysts with reduced reactivity.

[0043] The catalyst regeneration gas contains oxygen.

[0044] As an example, the catalyst regeneration gas contains air and pure oxygen.

[0045] As an example, the method for monitoring the catalytic activity of the transition metal oxide catalyst and / or noble metal oxide catalyst is as follows:

[0046] Waste liquid buffer tanks are installed at the bottom of both the primary reactor 2 and the secondary reactor 5. Each waste liquid buffer tank is equipped with an online detection device to monitor the concentrations of unsymmetrical dimethylhydrazine, formaldehyde, ammonia nitrogen, and COD. When the monitored concentration exceeds the set value, it is determined that the catalytic activity of the transition metal oxide catalyst and / or noble metal oxide catalyst has decreased to the threshold. The feed of unsymmetrical dimethylhydrazine wastewater is immediately stopped, and catalyst regeneration gas is introduced to regenerate the transition metal oxide catalyst and / or noble metal oxide catalyst with reduced reactivity, that is, to restore its catalytic activity through oxidation.

[0047] As an implementable mode of the present application, the reaction temperature for oxidizing the transition metal oxide catalyst or / and the noble metal oxide catalyst is 320-370°C, and the reaction time is 50-70 min.

[0048] As an implementable mode of the present application, the catalyst may be in the form of solid powder, solid particles, or the catalyst may be supported on a solid carrier.

[0049] As an implementable mode of the present application, the transition metal oxide catalyst comprises at least one of titanium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide and copper oxide.

[0050] As an example, the transition metal oxide may comprise at least one of TiO₂, MnO₂, MnO, Mn₃O₄, Fe₂O₃, CoO, CrO, Cr₂O₃, CrO₃, CuO, CuMn₂O₄, xFe₂O₃·(1-x)MnO₂, xFe₂O₃·(1-x)CuO and xFe₂O₃·(1-x)CoO, where 0<x<1; activated carbon, molecular sieve or montmorillonite can be used as the carrier for the transition metal oxide.

[0051] As an implementable mode of the present application, the noble metal oxide catalyst may be oxides of metals such as platinum, palladium, rhodium, silver and ruthenium.

[0052] As an implementable mode of the present application, the exhaust gas generated in the primary reactor and the secondary reactor is treated and then discharged, and the treatment of the exhaust gas comprises the following steps:

[0053] The exhaust gas passes through a filter to intercept and filter dust, then is detected by an online VOC monitor, after the VOC concentration reaches the standard, the exhaust gas is cooled by a heat exchanger, and the cooled exhaust gas is pumped out for discharge.

[0054] As an implementable mode of the present application, the temperature for catalytic oxidation of unsymmetrical dimethylhydrazine wastewater is 85-95°C.

[0055] As an implementable mode of the present application, the one-time feeding amount of the unsymmetrical dimethylhydrazine wastewater is about 500 L, and the catalyst loading amount in each reactor is generally 110-130 kg.

[0056] As an implementable mode of the present application, the reaction temperature for catalytic oxidation of the intermediate products is 80-120°C.

[0057] As an implementable mode of the present application, the primary reactor 2 and / or the secondary reactor 5 is / are packed tower reactors.

[0058] As one possible implementation of this application, the primary reactor 2 and / or the secondary reactor 5 are each equipped with a waste liquid buffer tank for temporarily storing the treated waste liquid.

[0059] As one possible implementation method of this application, the upper limit of the concentration of unsymmetrical dimethylhydrazine in the wastewater is 800-1800 mg / L. Of course, this method is also applicable to the degradation of wastewater with lower concentrations of unsymmetrical dimethylhydrazine.

[0060] To safely and efficiently degrade unsymmetrical dimethylhydrazine (UDMH) wastewater, this application employs a two-stage reactor connected in series to catalytically oxidize UDMH at low temperatures, generating nitrogen, carbon dioxide, and water. Simultaneously, to prevent reduced catalyst activity from affecting the degradation effect, an online wastewater monitoring instrument is installed after each reactor stage. The concentrations of UDMH, formaldehyde, ammonia nitrogen, and COD in the wastewater are used to determine if the catalyst activity has decreased. The concentrations of each harmful component in the wastewater must be below set standards to allow for timely oxidative regeneration of the catalyst, enhancing its catalytic activity. This effectively ensures that the degradation effect of UDMH consistently meets standards during the wastewater treatment process, resulting in treated wastewater that complies with regulations.

[0061] As one possible implementation method of this application, this application provides a unsymmetrical dimethylhydrazine wastewater treatment system for implementing the above method, including a feed tank 1, a primary reactor 2 and a secondary reactor 5 connected in series. The primary reactor 2 is provided with a feed inlet and a primary exhaust gas outlet, and the secondary reactor 5 is provided with a feed inlet and a secondary exhaust gas outlet.

[0062] A first filter is installed at the primary exhaust gas outlet, and the first exhaust gas online detector 4 and a heat exchanger are connected in sequence after the first filter;

[0063] A second filter is installed at the secondary exhaust gas outlet, and the second filter is connected in sequence to the second exhaust gas online detector 7 and the heat exchanger.

[0064] Both the primary reactor 2 and the secondary reactor 5 are packed tower reactors, which are filled with the aforementioned transition metal oxide catalyst and / or noble metal oxide catalyst. A primary waste liquid buffer tank 3 is installed on the pipeline connecting the primary reactor 2 and the secondary reactor 5, and a secondary waste liquid buffer tank 6 is connected to the bottom of the secondary reactor 5. Both waste liquid buffer tanks are equipped with online wastewater detectors for temporarily storing the treated waste liquid and simultaneously detecting the concentrations of unsymmetrical dimethylhydrazine, formaldehyde, ammonia nitrogen, and COD.

[0065] In addition, primary reactor 2 and secondary reactor 5 are equipped with waste gas recirculation pipelines to send the waste gas produced back to the reactors for further reaction.

[0066] The primary reactor 2 is heated by microwave, and the secondary reactor 5 is also heated by microwave.

[0067] It should be noted that the reactor configuration can be selected according to the VOCs gas volume. In addition to the primary / secondary reactor 5, multiple reactors can be configured to ensure complete inorganic / harmless treatment of waste liquid and tail gas. If it is necessary to increase the number of reactor stages, the structure and reaction process are the same as those of the secondary reactor 5, and will not be described in detail here.

[0068] After high-concentration unsymmetrical dimethylhydrazine (UDMH) wastewater is degraded using the method described in this application, the UDMH content is ≤0.5 mg / L, formaldehyde content is ≤1 mg / L, ammonia nitrogen content is ≤40 mg / L, and CODcr content is ≤100 mg / L, which meets the requirements of GB14374-1993.

[0069] The technical solutions described above in this application will be explained in detail below with reference to specific embodiments.

[0070] Example 1

[0071] A method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater includes the following steps:

[0072] S10. 110 kg of transition metal oxide catalyst is loaded into primary reactor 2 and secondary reactor 5.

[0073] 500L of unsymmetrical dimethylhydrazine (UDMH) wastewater was added to the primary reactor 2 via a pump. Microwave heating was used to maintain the temperature at 90°C. Stirring was employed to ensure thorough mixing of the transition metal oxide catalyst and the UDMH wastewater, leading to catalytic oxidation. At this reaction temperature, some of the UDMH and intermediate products generated during catalytic oxidation were vaporized; the gas phase was then recycled back to the primary reactor 2. The reaction lasted for 1 hour.

[0074] S20. The wastewater treated in the primary reactor 2 is filtered through the bottom filter screen and discharged into the primary wastewater buffer tank 3. After being monitored by an online wastewater analyzer, it is then introduced into the secondary reactor 5. In the secondary reactor 5, a stirring method is used to catalytically oxidize unreacted dimethylhydrazine and various intermediate products in the wastewater using a transition metal oxide catalyst. The reaction temperature is controlled at 100℃. At this reaction temperature, some of the unreacted dimethylhydrazine and intermediate products generated by catalytic oxidation will vaporize, and the gas phase needs to be recycled back to the secondary reactor 5. The reaction lasts for 1 hour.

[0075] The transition metal oxide catalyst consists of 20 wt% TiO2, 25 wt% MnO2, 20 wt% Mn3O4, 10 wt% Fe2O3, 15 wt% CrO3 and 10 wt% CuMn2O4.

[0076] S30. The wastewater treated by the secondary reactor 5 is filtered through the bottom filter screen of the reactor and then discharged into the secondary waste liquid buffer tank 6. It is then monitored by an online wastewater monitoring instrument. After the concentrations of unsymmetrical dimethylhydrazine, formaldehyde, ammonia nitrogen, COD and other substances meet the standards, the waste liquid is naturally cooled to below 40°C and then pumped out for discharge.

[0077] The exhaust gases produced by primary reactor 2 and secondary reactor 5 are ultimately discharged after passing through corresponding filters and online exhaust gas detectors, and then cooled by heat exchangers.

[0078] When the concentrations of unsymmetrical dimethylhydrazine, formaldehyde, ammonia nitrogen, and COD in the waste liquid buffer tanks at the bottom of primary reactor 2 and secondary reactor 5 exceed the set values, the feeding of unsymmetrical dimethylhydrazine wastewater is immediately stopped, and catalyst regeneration gas is introduced into the reactor corresponding to the online detector. The temperature is controlled at 350°C, and the reaction time is 60 minutes. After the reaction is completed, wastewater is added again for continued wastewater treatment. For example, if formaldehyde is detected to exceed the standard in the waste liquid of primary waste liquid buffer tank 3, catalyst regeneration gas, which is air, is introduced into primary reactor 2.

[0079] The method described in this embodiment was used to degrade wastewater with a concentration of unsymmetrical dimethylhydrazine (UDMH) of 1500 mg / L. After treatment, the concentration of UDMH in the wastewater was 0.33 mg / L, the formaldehyde concentration was 0.35 mg / L, the ammonia nitrogen concentration was 8.77 mg / L, and the COD concentration was [not specified]. Cr The concentration was 80.98 mg / L, which meets the requirements of GB14374-1993.

[0080] Example 2

[0081] A method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater includes the following steps:

[0082] S10. 120 kg of transition metal oxide catalyst is loaded into primary reactor 2 and secondary reactor 5, and then preheated.

[0083] 500L of unsymmetrical dimethylhydrazine (UDMH) wastewater was added to the primary reactor 2 via a pump. Microwave heating was used to maintain the temperature at 92°C. Stirring was employed to ensure thorough mixing of the transition metal oxide catalyst and the UDMH wastewater, leading to catalytic oxidation and the generation of gaseous products. At this reaction temperature, some of the UDMH and intermediate products from the catalytic oxidation were vaporized; the gaseous phase was then recycled back to the primary reactor 2. The reaction lasted for 1 hour.

[0084] S20. The wastewater treated in the primary reactor 2 is filtered through the bottom filter screen and discharged into the primary wastewater buffer tank 3. After being monitored by an online wastewater analyzer, it is then introduced into the secondary reactor 5. In the secondary reactor 5, a stirring method is used to catalytically oxidize unreacted dimethylhydrazine and various intermediate products in the wastewater using a transition metal oxide catalyst. The reaction temperature is controlled at 80°C. At this reaction temperature, some of the unreacted dimethylhydrazine and intermediate products generated by catalytic oxidation will vaporize, and the gas phase needs to be recycled back to the secondary reactor 5. The reaction lasts for 1 hour.

[0085] The transition metal oxide catalyst includes 20wt% TiO2, 25wt% CoO, 20wt% Mn3O4, 10wt% Fe2O3, 15wt% CrO3 and 10wt% Cr2O3.

[0086] The exhaust gases produced by primary reactor 2 and secondary reactor 5 are ultimately discharged after passing through corresponding filters and online exhaust gas detectors, and then cooled by heat exchangers.

[0087] S30. The wastewater treated by the secondary reactor 5 is filtered through the bottom filter screen of the reactor and then discharged into the secondary waste liquid buffer tank 6. It is then monitored by an online monitoring instrument. After the concentrations of unsymmetrical dimethylhydrazine, formaldehyde, ammonia nitrogen, COD and other substances meet the standards, the waste liquid is naturally cooled to below 40°C and then pumped out for discharge.

[0088] The waste gas generated in the secondary reactor 5 passes through the second filter to intercept and filter dust, and then is detected by the second waste gas online monitoring instrument. After the VOC concentration meets the standard, the waste gas is cooled by the heat exchanger. After the waste gas is cooled to below 30°C, it is extracted and discharged.

[0089] When the concentrations of unsymmetrical dimethylhydrazine, formaldehyde, ammonia nitrogen, and COD in the waste liquid buffer tank reach the set values, the feeding of unsymmetrical dimethylhydrazine wastewater is immediately stopped, and catalyst regeneration gas is introduced into the reactor corresponding to the wastewater online monitoring instrument. The temperature is controlled at 240℃ and the reaction time is 50 minutes. After the reaction is completed, wastewater is added again for continued wastewater treatment. For example, if the concentration of unsymmetrical dimethylhydrazine in the primary waste liquid buffer tank 3 reaches the set value, catalyst regeneration gas, which is air, is introduced into the primary reactor 2.

[0090] The method described in this embodiment was used to degrade wastewater with a concentration of unsymmetrical dimethylhydrazine (UDMH) of 1250 mg / L. After treatment, the concentration of UDMH in the wastewater was 0.30 mg / L, the concentration of formaldehyde was 0.31 mg / L, the concentration of ammonia nitrogen was 8.65 mg / L, and the COD concentration was [not specified]. Cr The concentration was 82.03 mg / L, which meets the requirements of GB14374-1993.

[0091] Example 3

[0092] A method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater includes the following steps:

[0093] S10. 130 kg of transition metal oxide catalyst is loaded into primary reactor 2 and secondary reactor 5, and then preheated.

[0094] 500L of unsymmetrical dimethylhydrazine (UDMH) wastewater was added to the primary reactor 2 via a pump. Microwave heating was used to maintain the temperature at 95°C. Stirring ensured thorough mixing of the transition metal oxide catalyst and UDMH wastewater, leading to catalytic oxidation and the generation of gaseous products. At this reaction temperature, some of the UDMH and intermediate products from the catalytic oxidation were vaporized; the gaseous phase was then recycled back to primary reactor 2. The reaction lasted for 1 hour.

[0095] S20. The wastewater treated in the primary reactor 2 is filtered through the bottom filter screen and discharged into the primary wastewater buffer tank 3. After being monitored by an online wastewater analyzer, it is then introduced into the secondary reactor 5. In the secondary reactor 5, a stirring method is used to catalytically oxidize unreacted dimethylhydrazine and various intermediate products in the wastewater using a transition metal oxide catalyst. The reaction temperature is controlled at 80°C. At this reaction temperature, some of the unreacted dimethylhydrazine and intermediate products generated by catalytic oxidation will vaporize, and the gas phase needs to be recycled back to the secondary reactor 5. The reaction lasts for 1 hour.

[0096] The transition metal oxide catalyst includes 35 wt% MnO2, 20 wt% Mn3O4, 10 wt% CuO, 15 wt% CrO3 and 20 wt% CuMn2O4.

[0097] The exhaust gases produced by primary reactor 2 and secondary reactor 5 are ultimately discharged after passing through corresponding filters and online exhaust gas detectors, and then cooled by heat exchangers.

[0098] S30. The wastewater treated by the secondary reactor 5 is filtered through the bottom filter screen of the reactor and then discharged into the secondary waste liquid buffer tank 6. It is then monitored by an online waste liquid monitoring instrument. After the concentrations of unsymmetrical dimethylhydrazine, formaldehyde, ammonia nitrogen, COD and other substances meet the standards, the waste liquid is naturally cooled to below 40°C and then pumped out for discharge.

[0099] When the concentrations of unsymmetrical dimethylhydrazine (UDMH), formaldehyde, ammonia nitrogen, and COD in the wastewater buffer tanks at the bottom of primary reactor 2 and secondary reactor 5 exceed the set values, the feeding of UDMH wastewater is immediately stopped. Catalyst regeneration gas is introduced into the reactor corresponding to the wastewater online monitoring instrument, the temperature is controlled at 370℃, and the reaction time is 50 minutes. After the reaction is completed, wastewater is added again for continued wastewater treatment. For example, if formaldehyde is detected to exceed the standard in the wastewater of primary wastewater buffer tank 3, catalyst regeneration gas is introduced into primary reactor 2. The catalyst regeneration gas includes 40 wt% oxygen and the remainder is nitrogen.

[0100] The method described in this embodiment was used to degrade wastewater with a concentration of unsymmetrical dimethylhydrazine (UDMH) of 1720 mg / L. After treatment, the concentration of UDMH in the wastewater was 0.48 mg / L, the concentration of formaldehyde was 0.61 mg / L, the concentration of ammonia nitrogen was 30.2 mg / L, and the COD concentration was [not specified]. Cr The concentration was 88.96 mg / L, which meets the requirements of GB14374-1993.

[0101] Example 4

[0102] A method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater includes the following steps:

[0103] S10. 125 kg of transition metal oxide catalyst is loaded into primary reactor 2 and secondary reactor 5, and then preheated.

[0104] 500L of unsymmetrical dimethylhydrazine (UDMH) wastewater was added to the primary reactor 2 via a pump. Microwave heating was used to maintain the temperature at 88°C. Stirring was employed to ensure thorough mixing of the transition metal oxide catalyst and the UDMH wastewater, leading to catalytic oxidation. At this reaction temperature, some of the UDMH and intermediate products generated during catalytic oxidation were vaporized; the gas phase was then recycled back to the primary reactor 2. The reaction lasted for 1 hour.

[0105] S20. The wastewater treated by the primary reactor 2 is filtered through the bottom filter screen and discharged into the primary waste liquid buffer tank 3. After being monitored by an online wastewater analyzer, the wastewater is then catalytically oxidized in the secondary reactor 5 using a stirring method with a transition metal oxide catalyst. The reaction temperature is controlled at 120℃. At this reaction temperature, some of the unsymmetrical dimethylhydrazine and intermediate products generated by catalytic oxidation will vaporize, and the gas phase needs to be recycled back to the secondary reactor 5. The reaction lasts for 1 hour.

[0106] The transition metal oxide catalyst includes 20wt% MnO, 20wt% Mn3O4, 15wt% Fe2O3, 15wt% CrO3, 10wt% CuMn2O4 and 20wt% 0.3Fe2O3·0.7CuO.

[0107] The exhaust gases produced by primary reactor 2 and secondary reactor 5 are ultimately discharged after passing through corresponding filters and online exhaust gas detectors, and then cooled by heat exchangers.

[0108] S30. The wastewater treated by the secondary reactor 5 is filtered through the bottom filter screen of the reactor and then discharged into the secondary waste liquid buffer tank 6. It is then monitored by an online waste liquid monitoring instrument. After the concentrations of unsymmetrical dimethylhydrazine, formaldehyde, ammonia nitrogen, COD and other substances meet the standards, the waste liquid is naturally cooled to below 40°C and then pumped out for discharge.

[0109] When the concentrations of unsymmetrical dimethylhydrazine, formaldehyde, ammonia nitrogen, and COD in the waste liquid buffer tank at the bottom of primary reactor 2 or secondary reactor 5 exceed the set values, the feeding of unsymmetrical dimethylhydrazine wastewater is immediately stopped, and catalyst regeneration gas is introduced into the reactor corresponding to the online detector. The temperature is controlled at 345°C, and the reaction time is 70 minutes. After the reaction is completed, wastewater is added again for continued wastewater treatment. For example, if COD is detected to exceed the standard in the waste liquid of primary waste liquid buffer tank 3, catalyst regeneration gas is introduced into primary reactor 2. The catalyst regeneration gas includes 30 wt% oxygen and the remainder is nitrogen.

[0110] The method described in this embodiment was used to degrade wastewater with a concentration of unsymmetrical dimethylhydrazine (UDMH) of 1580 mg / L. After treatment, the concentration of UDMH in the wastewater was 0.29 mg / L, the formaldehyde concentration was 0.45 mg / L, the ammonia nitrogen concentration was 28.8 mg / L, and the COD concentration was [not specified]. Cr The concentration is 70 mg / L, which meets the requirements of GB14374-1993.

[0111] Example 5

[0112] A method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater includes the following steps:

[0113] S10. 115 kg of transition metal oxide catalyst is loaded into primary reactor 2 and secondary reactor 5, and then preheated.

[0114] 500L of unsymmetrical dimethylhydrazine (UDMH) wastewater was added to the primary reactor 2 via a pump. Microwave heating was used to maintain the temperature at 85°C. Stirring was employed to ensure thorough mixing of the transition metal oxide catalyst and the UDMH wastewater, leading to catalytic oxidation. At this reaction temperature, some of the UDMH and intermediate products generated during catalytic oxidation were vaporized. The vapor phase was then recycled back to the primary reactor 2. The reaction lasted for 1 hour.

[0115] S20. The wastewater treated by the primary reactor 2 is filtered through the bottom filter screen and discharged into the primary wastewater buffer tank 3. After being monitored by an online wastewater analyzer, it is then introduced into the secondary reactor 5. In the secondary reactor 5, a stirring method is used to catalytically oxidize unreacted dimethylhydrazine and various intermediate products in the wastewater using a transition metal oxide catalyst. The reaction temperature is controlled at 80-120℃. At this reaction temperature, some of the unreacted dimethylhydrazine and intermediate products generated by catalytic oxidation will vaporize, and the gas phase needs to be recycled back to the secondary reactor 5. The reaction lasts for 1 hour.

[0116] The transition metal oxide catalyst includes 20wt% MnO, 25wt% Mn3O4, 15wt% Fe2O3, 5wt% Cr2O3, 25wt% CrO3 and 10wt% CuMn2O4.

[0117] The exhaust gases produced by primary reactor 2 and secondary reactor 5 are ultimately discharged after passing through corresponding filters and online exhaust gas detectors, and then cooled by heat exchangers.

[0118] S30. The wastewater treated by the secondary reactor 5 is filtered through the bottom filter screen of the reactor and then discharged into the secondary waste liquid buffer tank 6. It is then monitored by an online waste liquid monitoring instrument. After the concentrations of unsymmetrical dimethylhydrazine, formaldehyde, ammonia nitrogen, COD and other substances meet the standards, the waste liquid is naturally cooled to below 40°C and then pumped out for discharge.

[0119] When the concentrations of unsymmetrical dimethylhydrazine, formaldehyde, ammonia nitrogen, and COD in the waste liquid buffer tanks at the bottom of primary reactor 2 and secondary reactor 5 exceed the set values, the feeding of unsymmetrical dimethylhydrazine wastewater is immediately stopped, and catalyst regeneration gas is introduced into the reactor corresponding to the online detector. The temperature is controlled at 355°C, and the reaction time is 65 minutes. After the reaction is completed, wastewater is added again for continued wastewater treatment. For example, if formaldehyde is detected to exceed the standard in the waste liquid of primary waste liquid buffer tank 3, catalyst regeneration gas is introduced into secondary reactor 5. The catalyst regeneration gas includes 35 wt% oxygen and the remainder is nitrogen.

[0120] The method described in this embodiment was used to degrade wastewater with a concentration of unsymmetrical dimethylhydrazine (UDMH) of 1300 mg / L. After treatment, the concentration of UDMH in the wastewater was 0.33 mg / L, the formaldehyde concentration was 0.57 mg / L, the ammonia nitrogen concentration was 37 mg / L, and the COD concentration was [not specified]. Cr The concentration is 84 mg / L, which meets the requirements of GB14374-1993.

[0121] Comparative Example 1

[0122] A method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater includes the following steps:

[0123] 110 kg of transition metal oxide catalyst was packed into primary reactor 2 and secondary reactor 5;

[0124] 500L of unsymmetrical dimethylhydrazine (UDMH) wastewater was added to the primary reactor 2 via a pump. The reactor was electrically heated and maintained at 85–95°C. Stirring was used to ensure thorough mixing of the transition metal oxide catalyst and the UDMH wastewater, leading to catalytic oxidation. At this reaction temperature, some of the UDMH and intermediate products from the catalytic oxidation were vaporized; the gas phase was then recycled back to the primary reactor 2. The reaction lasted for 1 hour.

[0125] S20. The wastewater treated in the primary reactor 2 is filtered through the bottom filter screen and discharged into the primary wastewater buffer tank 3. After being monitored by an online wastewater analyzer, it is then introduced into the secondary reactor 5. In the secondary reactor 5, a stirring method is used to catalytically oxidize unreacted dimethylhydrazine and various intermediate products in the wastewater using a transition metal oxide catalyst. The reaction temperature is controlled at 80-120℃. At this reaction temperature, some of the unreacted dimethylhydrazine and intermediate products generated by catalytic oxidation will vaporize, and the gas phase needs to be recycled back to the secondary reactor 5. The reaction lasts for 1 hour.

[0126] The transition metal oxide catalyst consists of 20 wt% TiO2, 25 wt% MnO2, 20 wt% Mn3O4, 10 wt% Fe2O3, 15 wt% CrO3 and 10 wt% CuMn2O4.

[0127] The exhaust gases produced by primary reactor 2 and secondary reactor 5 are ultimately discharged after passing through corresponding filters and online exhaust gas detectors, and then cooled by heat exchangers.

[0128] S30. The wastewater treated by the secondary reactor 5 is filtered through the bottom filter screen of the reactor and then discharged into the secondary waste liquid buffer tank 6. It is then monitored by an online waste liquid monitoring instrument. After the concentrations of unsymmetrical dimethylhydrazine, formaldehyde, ammonia nitrogen, COD and other substances meet the standards, the waste liquid is naturally cooled to below 40°C and then pumped out for discharge.

[0129] When the concentrations of unsymmetrical dimethylhydrazine, formaldehyde, ammonia nitrogen, and COD in the waste liquid buffer tanks at the bottom of primary reactor 2 and secondary reactor 5 exceed the set values, the feeding of unsymmetrical dimethylhydrazine wastewater is immediately stopped, and catalyst regeneration gas is introduced into the reactor corresponding to the online detector. The temperature is controlled at 350°C, and the reaction time is 60 minutes. After the reaction is completed, wastewater is added again for continued wastewater treatment. For example, if formaldehyde is detected to exceed the standard in the waste liquid of primary waste liquid buffer tank 3, catalyst regeneration gas, which is air, is introduced into primary reactor 2.

[0130] The method described in this embodiment was used to degrade wastewater with a concentration of unsymmetrical dimethylhydrazine (UDMH) of 1500 mg / L. After treatment, the concentration of UDMH in the wastewater was 0.66 mg / L, the concentration of formaldehyde was 2.1 mg / L, the concentration of ammonia nitrogen was 66 mg / L, and the COD concentration was [not specified]. Cr The concentration is 125 mg / L, which does not meet the requirements of GB14374-1993.

[0131] The above description is merely an optional embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the inventive concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater, characterized in that, Includes the following steps: Unsymmetrical dimethylhydrazine (UDMH) wastewater is fed into a primary reactor, where it is catalytically oxidized using transition metal oxide catalysts and / or noble metal oxide catalysts. The primary reactor is microwave-heated. The concentration of UDMH in the wastewater is 800-1800 mg / L. The intermediate product generated in the primary reactor is fed into the secondary reactor, where it is catalytically oxidized using a transition metal oxide catalyst and / or a noble metal oxide catalyst; the secondary reactor is heated by microwave. The wastewater treated in the secondary reactor is discharged.

2. The method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater according to claim 1, characterized in that, It also includes the following steps: When the catalytic activity of the transition metal oxide catalyst and / or noble metal oxide catalyst decreases to a threshold, the feed of unsymmetrical dimethylhydrazine wastewater is stopped, and catalyst regeneration gas is introduced to regenerate the transition metal oxide catalyst and / or noble metal oxide catalyst with reduced reactivity.

3. The method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater according to claim 2, characterized in that, The regeneration reaction of the transition metal oxide catalyst and / or noble metal oxide catalyst is carried out at a temperature of 320-370℃ for a time of 50-70 min.

4. The method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater according to claim 1, characterized in that, The transition metal oxide catalyst includes at least one of titanium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, and copper oxide.

5. The method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater according to claim 1, characterized in that, The treatment of exhaust gas includes the following steps: The exhaust gas is filtered by a filter, monitored by an online monitoring instrument, cooled by a heat exchanger, and then discharged.

6. The method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater according to claim 1, characterized in that, The temperature for catalytic oxidation of unsymmetrical dimethylhydrazine wastewater is 85-95℃.

7. The method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater according to claim 1, characterized in that, The feed flow rate of the unsymmetrical dimethylhydrazine wastewater is 1.7-2.2 kg / h.

8. The method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater according to claim 1, characterized in that, The reaction temperature for the catalytic oxidation of the intermediate product is 80-120℃.

9. The method for catalytic oxidation treatment of unsymmetrical dimethylhydrazine wastewater according to claim 1, characterized in that, The primary reactor and / or secondary reactor are packed tower reactors.

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