Preparation method of metal-supported aluminum-based catalyst and application of metal-supported aluminum-based catalyst in nitrification wastewater treatment

Abstract

The invention discloses a preparation method of a metal-supported aluminum-based catalyst and application of the metal-supported aluminum-based catalyst in nitrification wastewater treatment.The catalyst takes an aluminum source as a carrier, zinc-niobium-iron metal as an active component and cucurbituril as a modifier and has the advantages of being good in adsorption effect and high in reaction efficiency. By combining with the nitrification wastewater treatment method provided by the invention, the recycling rate of dinitrotoluene can be effectively increased, the total nitrophenol content and COD content in the nitrification wastewater can be remarkably reduced, the blockage problem caused by separation of ammonium bicarbonate from equipment pipelines is solved, and the method has the advantages of high recycling rate, good treatment effect and long operation period.

Description

Technical Field

[0001] The invention belongs to the technical field of dinitrotoluene nitration wastewater treatment, and particularly relates to a preparation method of a metal-supported aluminum-based catalyst and application of the catalyst in dinitrotoluene nitration wastewater treatment. Background Art

[0002] The production process of dinitrotoluene (DNT) produces alkaline wastewater and acidic wastewater. The alkaline wastewater comes from the DNT washing and purification process and contains impurities such as dinitrotoluene, nitrocresol salts, carbonates, nitrates, carbonates and free ammonia. The acidic wastewater comes from the nitration waste acid stripping process and contains impurities such as dinitrotoluene, nitric acid, nitrous acid, and sulfuric acid. Since nitrobenzene compounds have a strong electrophilic group nitro, their chemical properties are stable, but they have the characteristics of poor biodegradability, difficulty in degradation, and high biological toxicity.

[0003] In industry, Fenton oxidation technology and biochemical treatment technology are often used in combination to treat nitration wastewater. Although this improves the biodegradability of the wastewater, the relatively expensive Fenton reagent has the disadvantages of low treatment efficiency and high cost. Patent CN1285514C combines the acidic wastewater and alkaline wastewater produced by dinitrotoluene washing with sulfuric acid concentrated distillate, and sequentially performs oil-water phase separation and toluene extraction. Although this improves the recovery rate of dinitrotoluene, it is unable to treat nitrocresol salts in the wastewater. Patent CN208414110U uses an extraction tower, a wastewater lightness removal tower, an evaporator and other devices to treat the alkaline wastewater produced by dinitrotoluene. Although the alkaline wastewater is reused as fresh wash water, due to the presence of substances such as free ammonia and carbonates in the wastewater, the gas phase at the top of the wastewater lightness removal tower easily forms ammonium bicarbonate precipitate after condensation, causing equipment and pipeline blockage and preventing long-term operation.

[0004] Therefore, existing methods for treating dinitrotoluene nitration wastewater still have significant limitations, including low treatment efficiency, high costs, and the inability to operate over a long period of time. Therefore, developing a dinitrotoluene nitration wastewater treatment method with high recovery rates, good treatment effects, and a long operating cycle has become an urgent problem in the industry. Summary of the Invention

[0005] In response to the above problems, the present invention aims to provide a method for preparing a metal-supported aluminum-based catalyst and its application in the treatment of dinitrotoluene nitration wastewater, which can effectively improve the recovery rate of dinitrotoluene, significantly reduce the total nitrophenol content and COD content in the nitration wastewater, and solve the problem of ammonium bicarbonate precipitation blockage in the equipment pipeline. It has the advantages of high recovery rate, good treatment effect and long operation cycle.

[0006] To achieve the above object, the present invention provides a method for preparing a metal-supported aluminum-based catalyst, comprising the following steps:

[0007] 1) Support preparation: An aluminum source, a silicon source, a structure directing agent, and deionized water are mixed, the filtered solid mixture is washed with deionized water, dried, and calcined in a nitrogen atmosphere at 700-1000° C. for 7-15 hours to obtain a support;

[0008] 2) preparing an impregnation solution: mixing a zinc source, a niobium source, an iron source, cucurbituril, and an organic solvent to obtain an impregnation solution;

[0009] 3) Impregnation: Mix the carrier from step 1) with the impregnation solution from step 2), adjust the pH to 7-9 with alkali solution, stir for 30-60 minutes, let stand for 8-12 hours, filter, wash with deionized water, and dry;

[0010] 4) Calcination: Calcinate the impregnated catalyst obtained in step 3) in a nitrogen atmosphere at 800-1200° C. for 10-20 hours, wash with deionized water, and dry to obtain a metal-supported aluminum-based catalyst.

[0011] Preferably, in step 1), the mass ratio of the aluminum source, the silicon source, the structure directing agent and the deionized water is 1:(0.1-0.6):(0.1-0.3):(1.1-5.4);

[0012] In step 2), the mass ratio of the aluminum source, zinc source, niobium source, iron source, cucurbituril and organic solvent is 1: (0.01-0.09): (0.01-0.07): (0.01-0.15): (0.1-1.5): (1.5-5.7).

[0013] Preferably, the aluminum source is one or more of pseudo-boehmite, ammonium aluminum carbonate, aluminum oxide, and aluminum sol with a solid content of 20 to 25 wt%;

[0014] The silicon source is one or more of tetraethyl orthosilicate, nano-silicon dioxide, amorphous silicon dioxide, and silica sol with a solid content of 20 to 30 wt%;

[0015] The structure directing agent is one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, N,N,N-trimethyl-1-adamantylammonium hydroxide, N,N-diethyl-2,6-dimethylpiperidinium hydroxide, and polyvinylpyrrolidone;

[0016] The zinc source is one or more of zinc nitrate, zinc acetate, zinc sulfate, and zinc chloride;

[0017] The niobium source is one or more of niobium acetate, niobium oxalate, niobium pentachloride, and niobium pentabromide;

[0018] The iron source is one or more of ferrous sulfate, ferrous acetate, ferrous nitrate, and ferrous chloride;

[0019] The organic solvent is one or more of ethanol, ethylene glycol, acetone, ethyl acetate, dichloromethane and chloroform.

[0020] Preferably, the alkali solution for adjusting the pH in step 3) is one or more of sodium hydroxide solution and potassium hydroxide solution; and the mass concentration of the alkali solution is 5wt% to 15wt%.

[0021] Another aspect of the present invention provides the use of the metal-supported aluminum-based catalyst prepared by the above preparation method in the treatment of dinitrotoluene nitration wastewater.

[0022] A dinitrotoluene nitration wastewater treatment process comprises the following steps:

[0023] 1) Acidic wastewater and alkaline wastewater are mixed in an acid adjustment mixer, and the pH is adjusted to 2-6 with dilute sulfuric acid. The acid-adjusted wastewater is introduced into an extraction tower filled with a catalyst, and toluene is added for decomposition reaction and extraction;

[0024] 2) collecting the extracted toluene in a toluene collecting tank, passing the extracted wastewater into an alkali adjustment mixer, adding alkali solution to adjust the pH to 7-11, preheating and stripping the alkali-adjusted wastewater, and cooling the bottom wastewater after stripping to obtain the treated wastewater;

[0025] Preferably, the dinitrotoluene nitration wastewater treatment process provided by the present invention further comprises:

[0026] 3) The gas phase at the top of the stripping tower is introduced into the absorption tower and absorbed with dilute sulfuric acid;

[0027] 4) Collect the absorbed liquid at the bottom of the absorption tower into a toluene collection tank.

[0028] Step 1) The acidic wastewater has a DNT content of 100-2000 mg / L, a nitrate content of 10-5000 mg / L, a sulfate content of 100-10000 mg / L, and a COD content of 100-10000 mg / L;

[0029] The DNT content in alkaline wastewater is 1000-2000 mg / L, the nitrocresol ammonium content is 10-5000 mg / L, the nitrate content is 10-5000 mg / L, the sulfate content is 100-10000 mg / L, the free ammonia content is 100-5000 mg / L, and the COD content is 1000-10000 mg / L.

[0030] Preferably, the parameters of the extraction tower in step 1) are set as follows: the number of theoretical plates in the upper non-catalyst area is 2 to 15, the number of theoretical plates in the lower non-catalyst area is 2 to 15, the extraction temperature is 60 to 80° C., the extraction pressure is 0.1 to 0.2 MPa, the metal-supported aluminum-based catalyst prepared by the above preparation method is loaded in the middle, the catalyst amount is 5 wt% to 10 wt% of the total hourly flow rate of the acidic wastewater and the alkaline wastewater, the acidified wastewater enters from the top of the extraction tower, and toluene enters from the bottom of the extraction tower;

[0031] Preferably, the extraction tower in step 1) is a packed tower, a plate tower, a rotary disc tower or a combination thereof, preferably a packed tower; preferably, the packed tower is a structured packing or a random packing or a combination thereof, preferably a structured packing; preferably, the packing material is metal, plastic, ceramic or glass or a combination thereof, preferably a metal packing; preferably, the metal packing material is 304, 304L, 316, 316L, Hastelloy or a combination thereof;

[0032] Preferably, the acid adjustment mixer in step 1) is one of K-type, SD-type, SH-type, SL-type, SV-type, SX-type, and SY-type static mixers, or a combination thereof; preferably, the mass concentration of dilute sulfuric acid is 5 to 10 wt%; preferably, the alkali adjustment mixer in step 2) is one of K-type, SD-type, SH-type, SL-type, SV-type, SX-type, and SY-type static mixers, or a combination thereof;

[0033] Preferably, the alkali solution for adjusting the pH in step 2) is one or more of ammonia water, sodium hydroxide solution, and potassium hydroxide solution; and the mass concentration of the alkali solution is 10 to 15 wt%.

[0034] Preferably, the mass ratio of acidic wastewater:alkaline wastewater:toluene is 1:(0.5-1.5):(0.4-4).

[0035] Preferably, in step 2), a stripping tower is used for stripping, and the stripping tower is a packed tower, a plate tower, or a combination thereof, preferably a packed tower; preferably, the packing is a structured packing or a random packing, or a combination thereof, preferably a structured packing; preferably, the packing material is metal, plastic, ceramic, or glass, or a combination thereof, preferably a metal packing; preferably, the metal packing material is 304, 304L, 316, 316L, Hastelloy, or a combination thereof;

[0036] The parameters of the stripping tower are set as follows: the number of theoretical plates is 5 to 20, the bottom temperature is 85 to 100°C, the top pressure is 0.1 to 0.2 MPa, and the preheated wastewater enters the bottom of the stripping tower;

[0037] Preferably, a reboiler is provided at the bottom of the stripping tower, and the reboiler uses 0.2-0.5 MPa steam as a heat source;

[0038] Preferably, the wastewater after alkali adjustment in step 2) is preheated with the wastewater at the bottom of the stripping tower to 75-85° C.; preferably, the cooler used for cooling the wastewater after stripping uses the return water of the absorption tower cooling water in step 3) as the cooling medium, and the wastewater after stripping is cooled to 30-70° C.

[0039] Preferably, in step 3), the absorption tower is cooled by an inner coil; preferably, the absorption tower is a packed tower, a plate tower, or a combination thereof, preferably a plate tower; preferably, the plate tower is a bubble tower, a sieve plate tower, a float valve tower, and a tongue-shaped tower, or a combination thereof, preferably a sieve plate tower; preferably, the sieve plate is made of metal, plastic, ceramic, or glass, or a combination thereof, preferably a metal sieve plate; preferably, the metal sieve plate is made of 304, 304L, 316, 316L, Hastelloy, or a combination thereof.

[0040] Preferably, the parameters of the absorption tower described in step 3) are set as follows: the number of theoretical plates is 5 to 20, the bottom temperature is 10 to 50° C., the pressure is 0.1 to 0.2 MPa, the gas phase of the stripping tower enters from the bottom of the absorption tower, the dilute sulfuric acid enters from the top of the absorption tower, the mass concentration of the dilute sulfuric acid is 5 to 10 wt%, and the flow rate of the dilute sulfuric acid is 5% to 25% of the alkaline wastewater;

[0041] The extraction tower employed in this invention not only enhances the extraction efficiency of dinitrotoluene (DNT) from nitration wastewater using toluene, but also utilizes a zinc-niobium-iron metal-supported aluminum-based catalyst in the extraction tower to oxidatively decompose nitrocresols in the nitration wastewater, significantly reducing the total nitrophenol content and COD levels in the wastewater. Furthermore, the catalyst, modified with cucurbituril, accelerates the catalytic oxidation of nitrocresols. Its supramolecular macrocyclic structure facilitates the recognition and enrichment of organic compounds such as toluene and DNT, accelerating the extraction of DNT from the toluene wastewater.

[0042] After extraction, the wastewater is stripped through a stripping tower. Most of the toluene, DNT, and other substances in the wastewater are stripped to the top of the tower and then enter the bottom of the absorption tower. The treated wastewater is then absorbed by the dilute sulfuric acid at the top of the absorption tower. The absorption tower with an internal coil cools the toluene, DNT, and water in the stripping tower vapor phase, capturing them at the bottom of the absorption tower and recycling them into a toluene collection tank, thereby increasing the recovery rate of toluene and DNT. Furthermore, the dilute sulfuric acid neutralizes the free ammonia in the vapor phase at the top of the stripping tower, preventing the formation of ammonium bicarbonate precipitates after condensation of the vapor phase, which could clog equipment and pipelines.

[0043] Compared with the prior art, the present invention has the following significant advantages:

[0044] 1) The extraction tower of the present invention is loaded with an aluminum-based catalyst supported by zinc-niobium-iron metal modified with cucurbituril, which decomposes nitrocresols by catalytic oxidation, significantly reducing the total nitrophenol content and COD content in the wastewater, while effectively improving the extraction efficiency of dinitrotoluene in toluene extraction nitration wastewater, and has the advantages of high recovery rate and good reaction effect.

[0045] 2) The present invention uses an absorption tower to cool the toluene, DNT and water in the gas phase of the stripping tower, and uses dilute sulfuric acid to neutralize the free ammonia in the gas phase of the stripping tower, thereby solving the problem of ammonium bicarbonate precipitation blocking the equipment pipeline and having the advantage of a long operating cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of the dinitrotoluene nitration wastewater treatment process of Examples 6 to 10 of the present invention.

[0047] Among them, C1 is the extraction tower, C2 is the stripping tower, C3 is the absorption tower, D1 is the toluene collection tank, E1 is the preheater, E2 is the reboiler, E3 is the cooler, M1 is the acid adjustment mixer, and M2 is the alkali adjustment mixer. DETAILED DESCRIPTION

[0048] In order to further disclose but not limit the present invention, the present invention is further described in detail below with reference to the embodiments.

[0049] Sources of nitrification wastewater:

[0050] The acidic wastewater and alkaline wastewater generated in the dinitrotoluene production process in the following examples and comparative examples were all from the same batch of industrial wastewater from the toluene diisocyanate (TDI) unit of Wanhua Chemical Group Co., Ltd., wherein the DNT content in the acidic wastewater was 1205 mg / L, the nitrate content was 973 mg / L, the sulfate content was 4612 mg / L, and the COD content was 1790 mg / L; the DNT content in the alkaline wastewater was 1539 mg / L, the nitrocresol ammonium content was 2141 mg / L, the free ammonia content was 1238 mg / L, the sulfate content was 524 mg / L, the nitrate content was 3503 mg / L, and the COD content was 2056 mg / L.

[0051] The calculation formula for total nitrophenol removal rate is:

[0052]

[0053] COD removal rate calculation formula:

[0054]

[0055] Source of raw materials:

[0056] Cucurbituril was purchased from Hubei Qifei Pharmaceutical Chemical Co., Ltd., product number QF2681;

[0057] Unless otherwise specified, other raw materials were purchased from commercial sources.

[0058] Test method:

[0059] COD test method: GB 11914-89 "Determination of Chemical Oxygen Demand of Water Quality" was used for determination.

[0060] Example 1

[0061] 100 g of pseudo-boehmite, 39.7 g of nano-silica, 25.6 g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide, and 350 g of deionized water were mixed, filtered, washed with deionized water, dried, placed in a muffle furnace, and calcined at 800° C. in a nitrogen atmosphere for 10 hours to obtain a carrier; 5 g of zinc chloride, 4 g of niobium acetate, 6 g of ferrous acetate, 65 g of cucurbituril, and 400 g of chloroform were mixed to obtain an impregnation solution; the carrier and the impregnation solution were mixed, the pH was adjusted to 8 with a 10 wt % NaOH solution, stirred for 45 minutes, allowed to stand for 10 hours, filtered, washed with deionized water, and dried; the impregnated catalyst was placed in a muffle furnace, calcined at 1200° C. in a nitrogen atmosphere for 10 hours, washed with deionized water, and dried to obtain Catalyst A.

[0062] Example 2

[0063] 100 g of pseudo-boehmite, 42.3 g of tetraethyl orthosilicate, 25.6 g of tetrapropylammonium hydroxide, and 200 g of deionized water were mixed, the solid mixture obtained after filtration was washed with deionized water, dried, placed in a muffle furnace, and calcined at 1000° C. in a nitrogen atmosphere for 12 h to obtain a carrier; 4 g of zinc acetate, 3 g of niobium oxalate, 4 g of ferrous sulfate, 85 g of cucurbituril, and 400 g of acetone were mixed to obtain an impregnation solution; the carrier and the impregnation solution were mixed, the pH was adjusted to 8 with a 10 wt % NaOH solution, stirred for 45 min, and then allowed to stand for 10 h, filtered, washed with deionized water, and dried; the impregnated catalyst was placed in a muffle furnace, calcined at 1200° C. in a nitrogen atmosphere for 10 h, washed with deionized water, and dried to obtain Catalyst B.

[0064] Example 3

[0065] 100 g of ammonium aluminum carbonate, 42.3 g of nano-silica, 29.1 g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide, and 350 g of deionized water were mixed, filtered, washed with deionized water, dried, placed in a muffle furnace, and calcined at 800° C. in a nitrogen atmosphere for 10 h to obtain a carrier; 1.5 g of zinc nitrate, 7 g of niobium pentachloride, 2.5 g of ferrous chloride, 130 g of cucurbituril, and 500 g of chloroform were mixed to obtain an impregnation solution; the carrier and the impregnation solution were mixed, the pH was adjusted to 9 with a 10 wt % NaOH solution, stirred for 45 min, allowed to stand for 12 h, filtered, washed with deionized water, and dried; the impregnated catalyst was placed in a muffle furnace, calcined at 1000° C. in a nitrogen atmosphere for 10 h, washed with deionized water, and dried to obtain Catalyst C.

[0066] Example 4

[0067] 100 g of aluminum oxide, 57.5 g of amorphous silica, 15.5 g of tetrapropylammonium hydroxide, and 350 g of deionized water were mixed, the solid mixture obtained after filtration was washed with deionized water, dried, placed in a muffle furnace, and calcined at 900° C. in a nitrogen atmosphere for 8 h to obtain a carrier; 3 g of zinc chloride, 3 g of niobium acetate, 4 g of ferrous acetate, 65 g of cucurbituril, and 200 g of chloroform were mixed to obtain an impregnation solution; the carrier and the impregnation solution were mixed, the pH was adjusted to 9 with a 10 wt % NaOH solution, the mixture was stirred for 55 min, and then allowed to stand for 12 h, filtered, washed with deionized water, and dried; the impregnated catalyst was placed in a muffle furnace, calcined at 1000° C. in a nitrogen atmosphere for 10 h, washed with deionized water, and dried to obtain Catalyst D.

[0068] Example 5

[0069] 100 g of aluminum sol with a solid content of 25 wt %, 12.1 g of tetraethyl orthosilicate, 11.7 g of N,N-diethyl-2,6-dimethylpiperidinium hydroxide, and 400 g of deionized water were mixed, the solid mixture obtained after filtration was washed with deionized water, dried, placed in a muffle furnace, and calcined at 700° C. in a nitrogen atmosphere for 15 h to obtain a carrier; 9 g of zinc nitrate, 1.2 g of niobium pentabromide, 14 g of ferrous sulfate, 35 g of cucurbituril, and 400 g of ethanol were mixed to obtain an impregnation solution; the carrier and the impregnation solution were mixed, the pH was adjusted to 8 with a 10 wt % NaOH solution, stirred for 35 min, and then allowed to stand for 8 h, filtered, washed with deionized water, and dried; the impregnated catalyst was placed in a muffle furnace, calcined at 900° C. in a nitrogen atmosphere for 10 h, washed with deionized water, and dried to obtain Catalyst E.

[0070] Example 6

[0071] Reference Figure 1As shown, 5 t / h of acidic wastewater and 5 t / h of alkaline wastewater are mixed in an acid-adjusting mixer M1, and the wastewater's pH is adjusted to 4 with 5 wt% dilute sulfuric acid. Acid-adjusting mixer M1 utilizes an SV-type static mixer. Extraction column C1 utilizes structured packing made of 316L, with 5 theoretical plates at the top and 5 at the bottom. The extraction temperature is 70°C, the extraction pressure is 0.1 MPa, and the center is loaded with 800 kg of catalyst A. The acid-adjusted wastewater is introduced from the top of extraction column C1, and 10 t / h of toluene is introduced from the bottom. The toluene and acid-adjusted wastewater undergo extraction and decomposition reactions in extraction column C1. The extracted toluene is then introduced into a toluene collection tank D1. The extracted wastewater is then passed into an alkali-adjusting mixer M2, where it is then fed with 15 wt% sodium hydroxide solution to adjust the pH to 10. Alkali-adjusting mixer M2 utilizes an SV-type static mixer. The treated wastewater is preheated to 80°C using the wastewater from the bottom of stripping tower C2. After preheating, the wastewater enters the bottom of stripping tower C2. Stripping tower C2 utilizes 316L structured packing with 11 theoretical plates. The reboiler E2 uses 0.2 MPa steam as a heat source, maintaining a bottom temperature of 100°C and a top pressure of 0.1 MPa. After preheating, the treated wastewater is cooled to 40°C in cooler E3, resulting in the treated wastewater. Absorption tower C3 utilizes 316L sieve plates with 10 theoretical plates. Cooling water from the inner coil maintains a bottom temperature of 20°C and a pressure of 0.1 MPa. The vapor phase from the top of stripping tower C2 is introduced into the bottom of absorption tower C3. 1 t / h of 5 wt% dilute sulfuric acid is introduced into the top of absorption tower C3 to absorb toluene, DNT, and free ammonia. The absorbed liquid from the bottom of absorption tower C2 is collected in a toluene collection tank.

[0072] After treatment, the total nitrophenol removal rate in the wastewater reached 98.7%, the COD removal rate was 84.1%, and the carbonate solid generation rate at the liquid phase outlet at the bottom of the absorption tower C3 was 0.011 mm / d.

[0073] Example 7

[0074] Reference Figure 1As shown, 5 t / h of acidic wastewater and 5 t / h of alkaline wastewater are mixed in an acid-adjusting mixer M1, and the wastewater's pH is adjusted to 5 with 5 wt% dilute sulfuric acid. Acid-adjusting mixer M1 utilizes an SV-type static mixer. Extraction column C1 utilizes structured packing made of 316L material, with 5 theoretical plates at the top and 5 at the bottom. The extraction temperature is 70°C, the extraction pressure is 0.1 MPa, and 600 kg of catalyst B is loaded in the middle. The acid-adjusted wastewater is introduced from the top of extraction column C1, and 5 t / h of toluene is introduced from the bottom. The toluene and acid-adjusted wastewater undergo extraction and decomposition reactions in extraction column C1. The extracted toluene is then introduced into a toluene collection tank D1. The extracted wastewater is then passed into an alkali-adjusting mixer M2, where 15 wt% ammonia is added to adjust the wastewater's pH to 10. Alkali-adjusting mixer M2 utilizes an SV-type static mixer. The treated wastewater is preheated to 80°C using the wastewater from the bottom of stripping tower C2. After preheating, the wastewater enters the bottom of stripping tower C2. Stripping tower C2 utilizes 316L structured packing with 8 theoretical plates. The reboiler E2 uses 0.2 MPa steam as a heat source, maintaining a bottom temperature of 100°C and a top pressure of 0.1 MPa. After preheating, the treated wastewater is cooled to 50°C in cooler E3, resulting in the treated wastewater. Absorption tower C3 utilizes 316L sieve plates with 10 theoretical plates. Cooling water from the inner coil maintains a bottom temperature of 30°C and a pressure of 0.1 MPa. The vapor phase from the top of stripping tower C2 is introduced into the bottom of absorption tower C3. 1 t / h of 5 wt% dilute sulfuric acid is introduced into the top of absorption tower C3 to absorb toluene, DNT, and free ammonia. The absorbed liquid from the bottom of absorption tower C2 is collected in a toluene collection tank.

[0075] After treatment, the total nitrophenol removal rate in the wastewater reached 97.3%, the COD removal rate was 82.9%, and the carbonate solid generation rate at the liquid phase outlet at the bottom of the absorption tower C3 was 0.017 mm / d.

[0076] Example 8

[0077] Reference Figure 1As shown, 3 t / h of acidic wastewater and 4.5 t / h of alkaline wastewater are mixed in an acid-adjusting mixer M1, and the wastewater pH is adjusted to 3 with 5 wt% dilute sulfuric acid. Acid-adjusting mixer M1 utilizes an SV-type static mixer. Extraction column C1 utilizes structured packing made of 316L material, with 7 theoretical plates at the top and 5 at the bottom. The extraction temperature is 70°C, the extraction pressure is 0.1 MPa, and the center is loaded with 750 kg of catalyst C. The acid-adjusted wastewater is introduced from the top of extraction column C1, and 3 t / h of toluene is introduced from the bottom. The toluene and acid-adjusted wastewater undergo extraction and decomposition reactions in extraction column C1. The extracted toluene is then introduced into a toluene collection tank D1. The extracted wastewater is then passed into an alkali-adjusting mixer M2, where 15 wt% ammonia is added to adjust the wastewater pH to 11. Alkali-adjusting mixer M2 utilizes an SV-type static mixer. The treated wastewater is preheated to 80°C using the wastewater from the bottom of stripping tower C2. After preheating, the wastewater enters the bottom of stripping tower C2. Stripping tower C2 utilizes 316L structured packing with 7 theoretical plates. The reboiler E2 uses 0.2 MPa steam as a heat source, maintaining a bottom temperature of 100°C and a top pressure of 0.1 MPa. After preheating, the treated wastewater is cooled to 30°C in cooler E3, resulting in the treated wastewater. Absorption tower C3 utilizes 316L sieve plates with 15 theoretical plates. Cooling water from the inner coil maintains a bottom temperature of 10°C and a pressure of 0.1 MPa. The vapor phase from the top of stripping tower C2 is introduced into the bottom of absorption tower C3. 1 t / h of 5 wt% dilute sulfuric acid is introduced into the top of absorption tower C3 to absorb toluene, DNT, and free ammonia. The absorbed liquid from the bottom of absorption tower C2 is collected in a toluene collection tank.

[0078] After treatment, the total nitrophenol removal rate in the wastewater reached 99.2%, the COD removal rate was 84.6%, and the carbonate solid generation rate at the liquid phase outlet at the bottom of the absorption tower C3 was 0.015 mm / d.

[0079] Example 9

[0080] Reference Figure 1As shown, 3 t / h of acidic wastewater and 4.5 t / h of alkaline wastewater are mixed in an acid-adjusting mixer M1, and the wastewater pH is adjusted to 5 with 5 wt% dilute sulfuric acid. Acid-adjusting mixer M1 utilizes a SY-type static mixer. Extraction column C1 utilizes structured packing made of 316L material, with 7 theoretical plates at the top and 5 at the bottom. The extraction temperature is 70°C, the extraction pressure is 0.1 MPa, and 640 kg of catalyst D is loaded in the middle. The acid-adjusted wastewater is introduced from the top of extraction column C1, and 3 t / h of toluene is introduced from the bottom. The toluene and acid-adjusted wastewater undergo extraction and decomposition reactions in extraction column C1. The extracted toluene is then introduced into a toluene collection tank D1. The extracted wastewater is then passed into an alkali-adjusting mixer M2, where 15 wt% sodium hydroxide solution is added to adjust the wastewater pH to 9. Alkali-adjusting mixer M2 utilizes a SY-type static mixer. The treated wastewater is preheated to 80°C using the wastewater from the bottom of stripping tower C2. After preheating, the wastewater enters the bottom of stripping tower C2. Stripping tower C2 utilizes 316L structured packing with 7 theoretical plates. The reboiler E2 uses 0.2 MPa steam as a heat source, maintaining a bottom temperature of 100°C and a top pressure of 0.1 MPa. After preheating, the treated wastewater is cooled to 50°C in cooler E3, resulting in the treated wastewater. Absorption tower C3 utilizes 316L sieve trays with 15 theoretical plates. Cooling water from the inner coil maintains a bottom temperature of 30°C and a pressure of 0.1 MPa. The vapor phase from the top of stripping tower C2 is introduced into the bottom of absorption tower C3. 1 t / h of 5 wt% dilute sulfuric acid is introduced into the top of absorption tower C3 to absorb toluene, DNT, and free ammonia. Finally, the absorbed liquid from the bottom of absorption tower C2 is collected in a toluene collection tank.

[0081] After treatment, the total nitrophenol removal rate in the wastewater reached 96.5%, the COD removal rate was 83.1%, and the carbonate solid generation rate at the liquid phase outlet at the bottom of the absorption tower C3 was 0.013 mm / d.

[0082] Example 10

[0083] Reference Figure 1As shown, 3 t / h of acidic wastewater and 4.5 t / h of alkaline wastewater are mixed in an acid-adjusting mixer M1, and the wastewater pH is adjusted to 6 with 5 wt% dilute sulfuric acid. Acid-adjusting mixer M1 utilizes a SY-type static mixer. Extraction column C1 utilizes structured packing made of 316L material, with 5 theoretical plates at the top and 5 at the bottom. The extraction temperature is 65°C, the extraction pressure is 0.1 MPa, and 480 kg of catalyst E is loaded in the middle. The acid-adjusted wastewater is introduced from the top of extraction column C1, and 3 t / h of toluene is introduced from the bottom. The toluene and acid-adjusted wastewater undergo extraction and decomposition reactions in extraction column C1. The extracted toluene is then introduced into a toluene collection tank D1. The extracted wastewater is then passed into an alkaline-adjusting mixer M2, where 15 wt% ammonia is added to adjust the wastewater pH to 9. Alkaline-adjusting mixer M2 utilizes a SY-type static mixer. The treated wastewater is preheated to 80°C using the wastewater from the bottom of stripping tower C2. After preheating, the wastewater enters the bottom of stripping tower C2. Stripping tower C2 utilizes 316L structured packing with 7 theoretical plates. The reboiler E2 uses 0.2 MPa steam as a heat source, maintaining a bottom temperature of 100°C and a top pressure of 0.1 MPa. After preheating, the treated wastewater is cooled to 60°C in cooler E3, resulting in the treated wastewater. Absorption tower C3 utilizes 316L sieve trays with 5 theoretical plates. Cooling water from the inner coil maintains a bottom temperature of 40°C and a pressure of 0.1 MPa. The vapor phase from the top of stripping tower C2 is introduced into the bottom of absorption tower C3. 1 t / h of 5 wt% dilute sulfuric acid is introduced at the top of absorption tower C3 to absorb toluene, DNT, and free ammonia. The absorbed liquid from the bottom of absorption tower C2 is collected in a toluene collection tank.

[0084] After treatment, the total nitrophenol removal rate in the wastewater reached 96.4%, the COD removal rate was 81.2%, and the carbonate solid generation rate at the liquid phase outlet at the bottom of the absorption tower C3 was 0.013 mm / d.

[0085] Comparative Example 1

[0086] The process conditions for treating the wastewater are the same as those in Example 6, except that no catalyst is loaded in the extraction tower.

[0087] After treatment, the total nitrophenol removal rate in the wastewater reached 49.3%, the COD removal rate was 42.5%, and the carbonate solid generation rate at the gas phase outlet at the top of the absorption tower C3 was 0.022 mm / d.

[0088] Comparative Example 2

[0089] 100 g of pseudo-boehmite, 39.7 g of nano-silica, 25.6 g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide, and 350 g of deionized water were mixed, filtered, washed with deionized water, dried, placed in a muffle furnace, and calcined at 800° C. in a nitrogen atmosphere for 10 h to obtain a carrier; 5 g of zinc chloride, 4 g of niobium acetate, 6 g of ferrous acetate, and 400 g of chloroform were mixed to obtain an impregnation solution; the carrier and the impregnation solution were mixed, the pH was adjusted to 8 with a 10 wt % NaOH solution, stirred for 45 min, allowed to stand for 10 h, filtered, washed with deionized water, and dried; the impregnated catalyst was placed in a muffle furnace, calcined at 1200° C. in a nitrogen atmosphere for 10 h, washed with deionized water, and dried to obtain Catalyst F.

[0090] The process conditions for treating the wastewater were the same as those in Example 6, except that the catalyst loaded in the extraction tower was replaced with catalyst F.

[0091] After treatment, the total nitrophenol removal rate in the wastewater reached 56.5%, the COD removal rate was 48.3%, and the carbonate solid generation rate at the liquid phase outlet at the bottom of the absorption tower C3 was 0.019 mm / d.

[0092] Comparative Example 3

[0093] 100 g of pseudo-boehmite, 39.7 g of nano-silica, 25.6 g of N,N,N-trimethyl-1-adamantyl ammonium hydroxide, and 350 g of deionized water were mixed, filtered, washed with deionized water, dried, placed in a muffle furnace, and calcined at 800° C. in a nitrogen atmosphere for 10 h to obtain a carrier; 5 g of zinc chloride, 6 g of ferrous acetate, 65 g of cucurbituril, and 400 g of chloroform were mixed to obtain an impregnation solution; the carrier and the impregnation solution were mixed, the pH was adjusted to 8 with a 10 wt % NaOH solution, stirred for 45 min, allowed to stand for 10 h, filtered, washed with deionized water, and dried; the impregnated catalyst was placed in a muffle furnace, calcined at 1200° C. in a nitrogen atmosphere for 10 h, washed with deionized water, and dried to obtain Catalyst G.

[0094] The process conditions for treating wastewater are the same as those in Example 6, except that the catalyst loaded in the extraction tower is replaced with catalyst G.

[0095] After treatment, the total nitrophenol removal rate in the wastewater reached 63.8%, the COD removal rate was 54.2%, and the carbonate solid generation rate at the liquid phase outlet at the bottom of the absorption tower C3 was 0.018 mm / d.

[0096] Comparative Example 4

[0097] The process conditions for treating wastewater are the same as those in Example 6, except that the absorption tower is replaced with a shell and tube condenser, that is, the gas phase at the top of the stripping tower C2 is passed into the shell and tube condenser for condensation.

[0098] After treatment, the total nitrophenol removal rate in the wastewater reached 98.4%, the COD removal rate was 83.3%, and the carbonate solid generation rate at the gas phase outlet at the top of the absorption tower C3 was 0.272 mm / d.

[0099] Table 1 Nitrification wastewater treatment effect

[0100]

[0101]

[0102] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing a metal-supported aluminum-based catalyst, characterized in that: The following steps are involved: 1) Carrier preparation: an aluminum source, a silicon source, a structure directing agent, and deionized water are mixed, filtered, washed, dried, and calcined to obtain a carrier; 2) preparing an impregnation solution: mixing a zinc source, a niobium source, an iron source, cucurbituril and an organic solvent to obtain an impregnation solution; 3) Impregnation: Mix the carrier from step 1) with the impregnation solution from step 2), adjust the pH, stir and allow to stand, filter, wash, and dry; 4) Calcination: Calcinate, wash, and dry the impregnated catalyst obtained in step 3) to obtain the metal-supported aluminum-based catalyst.

2. The preparation method according to claim 1, characterized in that In step 1), the mass ratio of the aluminum source, the silicon source, the structure directing agent and the deionized water is 1: (0.1-0.6): (0.1-0.3): (1.1-5.4).

3. The preparation method according to claim 1 or 2, characterized in that The mass ratio of the aluminum source, the zinc source, the niobium source, the iron source, the cucurbituril and the organic solvent is 1: (0.01-0.09): (0.01-0.07): (0.01-0.15): (0.1-1.5): (1.5-5.7).

4. The preparation method according to claim 1, characterized in that The aluminum source is one or more of pseudo-boehmite, ammonium aluminum carbonate, aluminum oxide, and aluminum sol with a solid content of 20 to 25 wt%; and / or: The silicon source is one or more of tetraethyl orthosilicate, nano-silicon dioxide, amorphous silicon dioxide, and silica sol with a solid content of 20 to 30 wt%; and / or: The structure directing agent is one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, N,N,N-trimethyl-1-adamantylammonium hydroxide, N,N-diethyl-2,6-dimethylpiperidinium hydroxide, and polyvinylpyrrolidone; and / or: The zinc source is one or more of zinc nitrate, zinc acetate, zinc sulfate, and zinc chloride; and / or: The niobium source is one or more of niobium acetate, niobium oxalate, niobium pentachloride, and niobium pentabromide; and / or: The iron source is one or more of ferrous sulfate, ferrous acetate, ferrous nitrate, and ferrous chloride; and / or: The organic solvent is one or more of ethanol, ethylene glycol, acetone, ethyl acetate, dichloromethane and chloroform.

5. The preparation method according to claim 1, characterized in that The calcination in step 1) is specifically carried out at 700-1000° C. for 7-15 hours in a nitrogen atmosphere; And / or: the calcination in step 4) is specifically carried out at 800-1200° C. for 10-20 hours under a nitrogen atmosphere.

6. The preparation method according to claim 1, characterized in that Step 3) The pH is adjusted to 7-9 using one or more of a 5-15 wt% sodium hydroxide solution and a potassium hydroxide solution. The mixture is stirred for 30-60 minutes and then allowed to stand for 8-12 hours.

7. A dinitrotoluene nitration wastewater treatment process, characterized in that: The following steps are involved: 1) mixing acidic wastewater and alkaline wastewater, adjusting the pH to 2-6 with dilute sulfuric acid, introducing the acidified wastewater into an extraction tower filled with a metal-supported aluminum-based catalyst prepared by the preparation method according to any one of claims 1-6, and adding toluene to carry out decomposition reaction and extraction; 2) collecting the extracted toluene in a toluene collecting tank, adjusting the pH of the extracted wastewater to 7-11 with alkali solution, preheating and stripping the alkali-adjusted wastewater, and cooling the bottom wastewater after stripping to obtain the treated wastewater; Preferably, 3) introducing the top gas phase after stripping into an absorption tower and absorbing it with dilute sulfuric acid; 4) Collect the absorbed liquid at the bottom of the absorption tower into a toluene collection tank.

8. The process according to claim 7, characterized in that In step 1), the mass ratio of acidic wastewater: alkaline wastewater: toluene is 1: (0.5-1.5): (0.4-4).

9. The process according to claim 7, characterized in that Step 1) The parameters of the extraction tower are set as follows: the number of theoretical plates in the upper non-catalyst area is 2 to 15, the number of theoretical plates in the lower non-catalyst area is 2 to 15, the extraction temperature is 60 to 80° C., the extraction pressure is 0.1 to 0.2 MPa, the catalyst prepared by the preparation method according to any one of claims 1 to 6 is loaded in the middle, the wastewater after acid adjustment enters from the top of the extraction tower, and toluene enters from the bottom of the extraction tower; And / or: in step 2), a stripping tower is used for stripping, and the parameters are set as follows: the number of theoretical plates is 5 to 20, the bottom temperature is 85 to 100° C., the top pressure is 0.1 to 0.2 MPa, and the preheated wastewater enters the bottom of the stripping tower; Preferably, the wastewater after alkali adjustment in step 2) is preheated to 75-85° C. using the wastewater at the bottom of the stripping tower; preferably, the cooler for the wastewater after stripping uses the return water from the absorption tower cooling water in step 3) as a cooling medium and is cooled to 30-70° C.; preferably, a reboiler E2 is provided at the bottom of the stripping tower, and the reboiler E2 uses 0.2-0.5 MPa steam as a heat source; And / or: the parameters of the absorption tower described in step 3) are set as follows: the number of theoretical plates is 5 to 20, the bottom temperature is 10 to 50° C., the pressure is 0.1 to 0.2 MPa, the gas phase of the stripping tower enters from the bottom of the absorption tower, and the dilute sulfuric acid enters from the top of the absorption tower.

10. The process according to claim 7, characterized in that The concentration of the dilute sulfuric acid in step 1) is 5-10wt%; the alkali solution in step 2) is one or more of ammonia water, sodium hydroxide solution, and potassium hydroxide solution, and the alkali solution concentration is 10-15wt%; the concentration of the dilute sulfuric acid in step 3) is 5-10wt%, and the flow rate of the dilute sulfuric acid is 5%-25% of the alkaline wastewater.

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