A zeolite-based catalyst, its preparation method and application

Abstract

The application discloses a zeolite molecular sieve-based catalyst and a preparation method and application thereof. The zeolite molecular sieve-based catalyst has low harmful element leaching, multiple active sites and high performance, and has excellent catalytic degradation performance and environment-friendly characteristics in environmental purification applications.

Description

Technical Field

[0001] This invention belongs to the field of environmental purification materials technology, specifically relating to a catalyst based on zeolite molecular sieves, its preparation method, and its application. Background Technology

[0002] With the development of industries such as manufacturing, animal husbandry, and aquaculture, various new pollutants, such as persistent organic pollutants, endocrine disruptors, antibiotics, and microplastics, are being discharged into water bodies, causing enormous harm to the natural ecosystem and human health. How to quickly, effectively, and safely eliminate the environmental damage caused by organic pollutants has become a hot topic of widespread concern in the scientific research field.

[0003] In recent years, researchers have discovered that advanced oxidation processes (AOPs), such as Fenton oxidation, electrochemical oxidation, photocatalysis, and ozone oxidation, have achieved good results in purifying organic pollutants. Among them, persulfate (PMS, HSO5)-based processes have shown promising effects. - Novel advanced oxidation technologies (SR-AOPs) exhibit advantages such as a wide pH range (pH = 2–9) and deep treatment capability when degrading new pollutants. Among transition metal catalysts, cobalt (Co) is considered a preferred metal for activating PMS; however, its application still faces challenges such as weak adsorption, limited active sites, and secondary pollution caused by cobalt ion leaching. Therefore, developing high-performance, low-leaching, and low-cost Co-based catalysts is of great significance for the industrial treatment of organic pollution. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a catalyst based on zeolite molecular sieve with low cobalt ion leaching and high catalytic activity.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides a catalyst based on zeolite molecular sieves, said catalyst being prepared by the following method:

[0007] (1) Calcining the zeolite molecular sieve in air at 300-550℃ for 3-6 hours (preferably at 400℃ for 4 hours) yields calcined zeolite molecular sieve;

[0008] (2) The calcined zeolite molecular sieve described in step (1) is uniformly dispersed in deionized water. Cobalt salt and metal M salt are added and dispersed evenly. The mixture is stirred at 60-80℃ for 4-7 hours (preferably at 70℃ for 6 hours) in a water bath. After standing at room temperature for 10-16 hours (preferably 12 hours), an alkaline additive is added and dispersed evenly. The mixture is then reacted at 135-145℃ for 6-12 hours (preferably at 140℃ for 8 hours) in a stainless steel autoclave lined with polytetrafluoroethylene. The resulting reaction solution is separated and washed to obtain Co. M / zeolite molecular sieve; the metal M salt is one or a mixture of two or more of magnesium salt, calcium salt, copper salt, and manganese salt (preferably magnesium salt or calcium salt); the ratio of the calcined zeolite molecular sieve, cobalt salt, and metal M salt is 1g:2-2.5mmol:8-10mmol (preferably 1g:2mmol:8mmol); the mass ratio of the calcined zeolite molecular sieve to the alkaline auxiliary agent is 1:6-7.2 (preferably 1:7.2); the alkaline auxiliary agent is one or a mixture of two of urea and hexamethylenetetramine;

[0009] (3) The CoM / zeolite molecular sieve obtained in step (2) is calcined in air atmosphere in a tube furnace at 400-600℃ for 3-8 hours (preferably calcination temperature 600℃, preferably calcination time 6 hours) to obtain a catalyst based on zeolite molecular sieve.

[0010] Further, the zeolite molecular sieve mentioned in step (1) is one or a mixture of two or more of the following: 13X zeolite molecular sieve, ZSM-5 zeolite molecular sieve, SSZ-13 zeolite molecular sieve, KIT-6 molecular sieve, AlPO4-5 zeolite molecular sieve, NaX zeolite molecular sieve, SBA-15 molecular sieve, and MCM-41 zeolite molecular sieve. In the embodiments of the present invention, it is 13X zeolite molecular sieve or MCM-41 zeolite molecular sieve.

[0011] Furthermore, the cobalt salt mentioned in step (2) is one or a mixture of two of Co(NO3)2·6H2O and CoCl2·6H2O.

[0012] Further, the metal M salt mentioned in step (2) is one or two of Mg(NO3)2·6H2O, MgCl2, Ca(NO3)2·4H2O, CaCl2, Cu(NO3)2·3H2O, CuCl2, Mn(NO3)2·4H2O, and MnCl2·4H2O (preferably the metal M salt is Mg(NO3)2·6H2O, MgCl2, Ca(NO3)2·4H2O, or CaCl2).

[0013] Furthermore, the volume of the deionized water in step (2) is 60-70 mL / g based on the mass of the calcined zeolite molecular sieve.

[0014] In an embodiment of the present invention, the separation and washing in step (2) is as follows: the reaction solution is naturally cooled at room temperature, washed sequentially with deionized water and anhydrous ethanol, and dried to obtain the CoM / zeolite molecular sieve.

[0015] Furthermore, the heating rate of calcination in step (3) is 2-5℃ / min (preferably 2℃ / min).

[0016] On the other hand, the present invention provides an application of the above-mentioned zeolite molecular sieve-based catalyst in the degradation of organic pollutants by activated persulfate (PMS).

[0017] Furthermore, the organic pollutant is one or more of metronidazole, sulfamethoxazole, perfluorooctanoic acid, bisphenol A, norfloxacin, and tetracycline. In one embodiment of the present invention, the organic pollutant is metronidazole.

[0018] The catalytic degradation function of the zeolite molecular sieve-based catalyst described in this invention is achieved by activating PMS. Therefore, those skilled in the art can anticipate that any organic pollutant that can be degraded using PMS is within the scope of protection of this invention.

[0019] Specifically, the application involves dispersing the zeolite molecular sieve-based catalyst in an aqueous solution of organic pollutants, adding persulfate, and then stirring to degrade the pollutants.

[0020] Furthermore, the concentration of organic pollutants in the aqueous solution is 10–200 mg / L.

[0021] Furthermore, the persulfate is one or a mixture of two of permonosulfate and perdisulfate; in one embodiment of the present invention, it is potassium peroxymonosulfate.

[0022] Furthermore, the mass of the catalyst based on zeolite molecular sieve is 0.25–2 g / L based on the volume of the aqueous solution of the organic pollutant.

[0023] Furthermore, the mass of the persulfate is 0.25–2 g / L based on the volume of the aqueous solution of the organic pollutant.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The catalyst of the zeolite molecular sieve prepared by the present invention uses soluble alkaline earth metal salts (preferably magnesium salts and calcium salts) to replace part of the cobalt salt, which effectively disperses and "blocks" the agglomeration of Co-O-Si particles, increases active sites, and improves the atomic utilization and dispersibility of Co catalysis.

[0026] 2. The catalyst of the zeolite molecular sieve prepared by this invention uses alkaline earth metal salts (magnesium salts and calcium salts) to replace part of the cobalt salts to form a composite structure. Compared with heavy metal salts, alkaline earth metal salts (magnesium salts and calcium salts) are more environmentally friendly. In the process of synthesis and use of zeolite molecular sieve catalysts, the added alkaline earth metal salts (magnesium salts and calcium salts) have a low leaching environmental risk and are green and environmentally friendly.

[0027] 3. The doping of metal salts in this invention can reduce the use of cobalt salts, maintain catalytic activity while reducing Co ion leaching (<1 mg / L), which meets the limits specified in the Integrated Wastewater Discharge Standard (GB8978-1996). At the same time, it helps to reduce the cost of catalyst preparation and has wide applicability to meet practical application needs.

[0028] 4. By controlling the temperature during calcination, this invention can further improve the stability of the synthesized phase in the catalyst based on zeolite molecular sieve and reduce the leaching of Co ions.

[0029] 5. The catalyst based on zeolite molecular sieve prepared by this invention has the advantages of low cost, easy recovery, and reusability.

[0030] 6. This invention grows ultrathin cobalt silicate nanosheets on the surface of zeolite molecular sieves, which can maximize the exposure of catalytic active sites and increase the specific surface area of ​​zeolite molecular sieve-based catalysts by utilizing the hollow porous structure of zeolite molecular sieves, resulting in excellent degradation efficiency and catalytic activity. Attached Figure Description

[0031] Figure 1 The standard PDF spectra of composite material A prepared in Example 1, composite material B prepared in Example 2, and CoMg / 13X and 13X molecular sieves prepared in Comparative Example 1 are shown.

[0032] Figure 2 SEM images at different scales of the 13X molecular sieve and the Co / 13X composite material prepared in Comparative Example 3: (a) and (b) are 13X molecular sieves, and (c) and (d) are Co / 13X composite materials.

[0033] Figure 3 These are TEM images of composite material C prepared in Example 3 at different scales. Detailed Implementation

[0034] Example 1

[0035] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0036] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication. Add 0.582g Co(NO3)2·6H2O (0.002mol) and 2.048g Mg(NO3)2·6H2O (0.008mol). Continue to disperse by sonication for 5min. Then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0037] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0038] (4) Take an appropriate amount of CoMg / 13X powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min and keep it at that temperature for 6 hours. Then cool it naturally in the tube furnace to obtain a catalyst based on zeolite molecular sieve, which is denoted as composite material A.

[0039] Example 2

[0040] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0041] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication. Add 0.582g Co(NO3)2·6H2O (0.002mol) and 0.888g CaCl2 (0.008mol). Continue to disperse by sonication for 5min. Then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0042] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoCa / 13X.

[0043] (4) Take an appropriate amount of CoCa / 13X powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min and keep it at that temperature for 6 hours. Then cool it naturally in the tube furnace to obtain a catalyst based on zeolite molecular sieve, which is denoted as composite material B.

[0044] Example 3

[0045] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0046] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication. Add 0.582g Co(NO3)2·6H2O (0.002mol) and 0.888g CaCl2 (0.008mol). Continue to disperse by sonication for 5min. Then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0047] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoCa / 13X.

[0048] (4) Take an appropriate amount of CoCa / 13X powder and place it in a tube furnace. Heat it to 400℃ at 2℃ / min and keep it at that temperature for 6 hours. Then cool it naturally in the tube furnace to obtain a catalyst based on zeolite molecular sieve, which is denoted as composite material C.

[0049] Example 4

[0050] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0051] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication. Add 0.582g Co(NO3)2·6H2O (0.002mol) and 2.048g Mg(NO3)2·6H2O (0.008mol). Continue to disperse by sonication for 5min. Then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0052] (3) Add 7.2g of hexamethylenetetramine to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0053] (4) Take an appropriate amount of CoMg / 13X powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min and keep it at that temperature for 6 hours. Then cool it naturally in the tube furnace to obtain a catalyst based on zeolite molecular sieve, which is denoted as composite material D.

[0054] Example 5

[0055] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0056] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication. Add 0.7275g Co(NO3)2·6H2O (0.0025mol) and 2.560g Mg(NO3)2·6H2O (0.01mol). Continue to disperse by sonication for 5min. Then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0057] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0058] (4) Take an appropriate amount of CoMg / 13X powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min and keep it at that temperature for 6 hours. Then cool it naturally in the tube furnace to obtain a catalyst based on zeolite molecular sieve, which is denoted as composite material E.

[0059] Example 6

[0060] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0061] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 0.582g of Co(NO3)2·6H2O and 2.048g of Mg(NO3)2·6H2O, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0062] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0063] (4) Take an appropriate amount of CoMg / 13X powder and place it in a tube furnace. Heat the furnace to 400℃ at a rate of 2℃ / min and hold for 6 hours. Allow the furnace to cool naturally to obtain a catalyst based on zeolite molecular sieve, denoted as composite material F.

[0064] Example 7

[0065] (1) Calcined MCM-41 molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: MCM-41, particle size D50=1.5μm) was calcined at 400℃ for 4h in air atmosphere to obtain calcined MCM-41 molecular sieve.

[0066] (2) Take 1g of calcined MCM-41 molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication. Add 0.7275g Co(NO3)2·6H2O (0.0025mol) and 2.560g Mg(NO3)2·6H2O (0.01mol). Continue to disperse by sonication for 5min. Then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0067] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / MCM-41.

[0068] (4) Take an appropriate amount of CoMg / MCM-41 powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min and keep it at that temperature for 6 hours. Then cool it naturally in the tube furnace to obtain a catalyst based on zeolite molecular sieve, which is denoted as composite material G.

[0069] Comparative Example 1

[0070] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0071] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 0.582g of Co(NO3)2·6H2O and 2.048g of Mg(NO3)2·6H2O, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0072] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0073] Comparative Example 2

[0074] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0075] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 0.582g of Co(NO3)2·6H2O and 2.048g of Mg(NO3)2·6H2O, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0076] (3) Add 2.4g of sodium hydroxide to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0077] (4) Take an appropriate amount of CoMg / 13X powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min, keep it at that temperature for 6h, and then let it cool naturally in the tube furnace to obtain the sample of Comparative Example 2.

[0078] Comparative Example 3

[0079] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0080] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 2.910g of Co(NO3)2·6H2O, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0081] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain Co / 13X.

[0082] Comparative Example 4

[0083] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0084] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 2.910g of Co(NO3)2·6H2O, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0085] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain Co / 13X.

[0086] (4) Take an appropriate amount of Co / 13X powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min and keep it at that temperature for 6 hours. Then cool it naturally in the tube furnace to obtain the sample of Comparative Example 4.

[0087] Comparative Example 5

[0088] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0089] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 0.582g of Co(NO3)2·6H2O and 2.376g of Zn(NO3)2·6H2O, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0090] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoZn / 13X.

[0091] (4) Take an appropriate amount of CoZn / 13X powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min, keep it at that temperature for 6h, and then let it cool naturally in the tube furnace to obtain the comparative sample 5.

[0092] Comparative Example 6

[0093] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0094] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 0.808g Fe(NO3)3·9H2O and 2.048g Mg(NO3)2·6H2O, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0095] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain FeMg / 13X.

[0096] (4) Take an appropriate amount of FeMg / 13X powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min, keep it at that temperature for 6h, and then let it cool naturally in the tube furnace to obtain the comparative sample 6.

[0097] Comparative Example 7

[0098] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0099] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication. Add 0.291g of Co(NO3)2·6H2O (0.001mol) and 2.304g of Mg(NO3)2·6H2O (0.009mol). Continue to disperse by sonication for 5min. Then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0100] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0101] (4) Take an appropriate amount of CoMg / 13X powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min, keep it at that temperature for 6h, and then let it cool naturally in the tube furnace to obtain the comparative sample 7.

[0102] Comparative Example 8

[0103] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0104] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication. Add 1.455g Co(NO3)2·6H2O (0.005mol) and 1.280g Mg(NO3)2·6H2O (0.005mol). Continue to disperse by sonication for 5min. Then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0105] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0106] (4) Take an appropriate amount of CoMg / 13X powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min, keep it at that temperature for 6h, and then let it cool naturally in the tube furnace to obtain the comparative sample 8.

[0107] Comparative Example 9

[0108] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0109] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 0.582g of Co(NO3)2·6H2O and 2.048g of Mg(NO3)2·6H2O, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0110] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 120℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0111] (4) Take an appropriate amount of CoMg / 13X powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min, keep it at that temperature for 6h, and then let it cool naturally in the tube furnace to obtain the comparative sample 9.

[0112] Comparative Example 10

[0113] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0114] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 0.582g of Co(NO3)2·6H2O and 2.048g of Mg(NO3)2·6H2O, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0115] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 90℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0116] (4) Take an appropriate amount of CoMg / 13X powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min, keep it at that temperature for 6h, and then let it cool naturally in the tube furnace to obtain the comparative sample 10.

[0117] Comparative Example 11

[0118] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0119] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 0.582g of Co(NO3)2·6H2O and 2.048g of Mg(NO3)2·6H2O, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0120] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0121] (4) Take an appropriate amount of CoMg / 13X powder and place it in a tube furnace. Heat it to 900℃ at 5℃ / min, keep it at that temperature for 2 hours, and then let it cool naturally in the tube furnace to obtain the comparative sample 11.

[0122] Comparative Example 12

[0123] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0124] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 0.582g of Co(NO3)2·6H2O and 0.888g of CaCl2, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0125] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoCa / 13X.

[0126] (4) Take an appropriate amount of CoCa / 13X powder and place it in a tube furnace. Heat it to 900℃ at 5℃ / min, keep it at that temperature for 2 hours, and then let it cool naturally in the tube furnace to obtain the comparative sample 12.

[0127] Comparative Example 13

[0128] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0129] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 0.582g of Co(NO3)2·6H2O and 2.048g of Mg(NO3)2·6H2O, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0130] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0131] (4) Take an appropriate amount of CoMg / 13X powder and place it in a tube furnace. Heat it to 700℃ at 2℃ / min, keep it at that temperature for 6 hours, and then let it cool naturally in the tube furnace to obtain the comparative sample 13.

[0132] Comparative Example 14

[0133] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0134] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 0.582g of Co(NO3)2·6H2O and 2.048g of Mg(NO3)2·6H2O, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0135] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 140℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0136] (4) Take an appropriate amount of CoMg / 13X powder and place it in a tube furnace. Pour nitrogen gas into the furnace and heat it to 900℃ at 5℃ / min. Keep it at that temperature for 2 hours and let it cool naturally in the tube furnace to obtain the comparative sample 14.

[0137] Comparative Example 15

[0138] (1) Calcine 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) at 400℃ for 4h in air atmosphere to obtain calcined 13X molecular sieve.

[0139] (2) Take 1g of calcined 13X molecular sieve and disperse it in 60mL of deionized water. Disperse it by sonication, add 0.582g of Co(NO3)2·6H2O and 2.048g of Mg(NO3)2·6H2O, continue to disperse by sonication for 5min, then place it in a water bath and stir magnetically at 70℃ for 6h. Take it out and let it stand at room temperature for 12h to obtain mixed solution A.

[0140] (3) Add 7.2g of urea to the mixed solution A, disperse it evenly by ultrasonication, transfer it to a stainless steel autoclave lined with polytetrafluoroethylene, react at 160℃ for 8h, cool naturally at room temperature, wash with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12h to obtain CoMg / 13X.

[0141] (4) Take an appropriate amount of CoMg / 13X powder and place it in a tube furnace. Heat it to 600℃ at 2℃ / min, keep it at that temperature for 6h, and then let it cool naturally in the tube furnace to obtain the comparative sample 15.

[0142] Application Comparison Experiment

[0143] 1. Organic matter catalytic degradation test: A 20 mg / L metronidazole solution was prepared to simulate organic pollutants. 0.025 g of samples from Examples 1-7 and Comparative Examples 1-15 were placed in 50 mL of metronidazole solution, and 0.025 g of potassium persulfate (PMS) was added. Small amounts of solution were taken for solid-liquid separation at 5 min, 30 min, and 60 min after the reaction. The absorbance of residual metronidazole in the solution was measured using a UV spectrophotometer. The degradation rate of metronidazole by the sample was calculated, as shown in Table 1.

[0144] 2. Co ion leaching test: Take 5 mL of the filtered degradation reaction solution and test the Co ion leaching concentration, as shown in Table 2.

[0145] Table 1 Sample Degradation Rate Data

[0146]

[0147] Table 2. Co leaching data of samples

[0148] sample Co leaching (mg / L) Example 1 0.16 Example 2 0.34 Example 3 0.35 Example 4 0.16 Example 5 0.13 Example 6 1.63 Comparative Example 1 2.30 Comparative Example 2 5.46 Comparative Example 3 26.90 Comparative Example 4 10.10 Comparative Example 5 5.61 Comparative Example 6 - Comparative Example 7 0.14 Comparative Example 8 6.80 Comparative Example 9 0.15 Comparative Example 10 7.74 Comparative Example 11 2.73 Comparative Example 12 0.23 Comparative Example 13 2.03 Comparative Example 14 4.73 Comparative Example 15 2.79

[0149] 1. As can be seen from Examples 1-7 in Table 1, the zeolite molecular sieve-based catalyst prepared in this invention can achieve efficient degradation of the target organic matter within only 5 minutes.

[0150] 2. As can be seen from Examples 1-5 in Table 2, the Co ion leaching level in the zeolite molecular sieve-based catalyst is within the limit specified in GB8978-1996 (<1 mg / L).

[0151] 3. The comparison between Example 1 and Comparative Example 6 in Table 1 shows that the catalytic performance of Co-based zeolite molecular sieve catalyst is significantly better than that of Fe-based zeolite molecular sieve catalyst.

[0152] 4. The comparison between Example 1 and Comparative Example 7 in Table 1 shows that reducing the amount of cobalt salt will reduce the catalytic performance of the zeolite molecular sieve catalyst.

[0153] 5. The comparison between Example 1 and Comparative Example 9 in Table 1 shows that the hydrothermal synthesis of CoMg / 13X composite material at a higher temperature (140℃) is beneficial to the degradation of organic matter after calcination.

[0154] 6. As can be seen from the comparison between Example 2 and Comparative Example 12 in Table 1, for Ca-doped zeolite molecular sieve catalysts, increasing the calcination temperature (900℃) will reduce their catalytic performance.

[0155] 7. The comparison between Examples 1 and 6 and Comparative Examples 1, 11 and 13 in Table 2 shows that calcination of the CoMg / 13X composite material can effectively inhibit the leaching of Co ions, but the leaching will increase when the calcination temperature is higher than 700℃.

[0156] 8. The comparison between Example 1, Example 4 and Comparative Example 2 shows that urea and hexamethylenetetramine have a better inhibitory effect on Co leaching than sodium hydroxide.

[0157] 9. The comparison between Examples 1-2 and Comparative Examples 3-5 in Table 2 shows that the doping of Mg and Ca elements in the catalyst of zeolite molecular sieves can maintain high efficiency in degradation while avoiding high leaching of Co ions.

[0158] 10. As can be seen from the comparison between Example 1 and Comparative Example 8 in Table 2, reducing the Mg doping ratio of the zeolite molecular sieve catalyst will increase the Co leaching.

[0159] 11. By comparing Example 1 and Comparative Examples 10 and 15 in Table 2, it can be shown that the CoMg / 13X composite material synthesized by lower temperature (90℃) water bath or higher temperature water (160℃) exhibits higher Co leaching during the degradation process after calcination (600℃).

[0160] Figure 1 The images show the standard PDF spectra of composite material A prepared in Example 1, composite material B prepared in Example 2, and CoMg / 13X and 13X molecular sieves prepared in Comparative Example 1. (From...) Figure 1 It can be seen that CoMg / 13X, composite material A, and composite material B retain some characteristic peaks of 13X. The "bun peak" between 20-30° is caused by the presence of amorphous SiO2. However, no crystal signal peaks related to Co are shown in the XRD patterns, possibly because the cobalt-containing compounds have small or amorphous grains. This is due to the doping and protection of Mg and Ca elements, which helps to suppress the leaching of Co ions.

[0161] Figure 2 SEM images at different scales of the 13X molecular sieve and the Co / 13X composite material prepared in Comparative Example 3: (a) and (b) show the 13X molecular sieve, and (c) and (d) show the Co / 13X composite material. From Figures (a) and (b), it can be seen that the 13X molecular sieve exhibits a 1-2 μm spherical structure and has a smooth surface. Figure 2 As can be seen from (c) and (d), ultrathin cobalt silicate nanosheets are distributed on the surface of 13X zeolite molecular sieve without any particle or agglomeration phenomenon. This indicates that the active Co is uniformly distributed on the surface of the molecular sieve, which is conducive to exposing more active sites. The ultrathin nanosheet structure has a higher specific surface area.

[0162] Figure 3 These are TEM images of composite material C prepared in Example 3 at different scales. Figure 3 (a) The composite material shown in the transmission electron microscope appears as 2-3 μm composite microspheres. Figure 3 (b) shows that thin nanosheet-like structures appear on the surface of the microspheres, which are consistent with... Figure 2 The Co / 13X composite material prepared in Comparative Example 3 has a similar structure.

Claims

1. A catalyst based on zeolite molecular sieves, characterized in that... The catalyst based on zeolite molecular sieve is prepared by the following method: (1) Calcined zeolite molecular sieves are obtained by calcining them in air at 300-550℃ for 3-6 hours. (2) The calcined zeolite molecular sieve described in step (1) is uniformly dispersed in deionized water, cobalt salt and metal M salt are added, and the mixture is evenly dispersed. The mixture is stirred and reacted at 60-80℃ for 4-7 hours, and then allowed to stand at room temperature for 10-16 hours. An alkaline additive is added and the mixture is evenly dispersed. The mixture is then reacted in a stainless steel autoclave lined with polytetrafluoroethylene at 135-145℃ for 6-12 hours. The resulting reaction solution is separated and washed to obtain CoM / zeolite molecular sieve. The metal M salt is one or a mixture of two or more magnesium salts and calcium salts. The ratio of the amount of calcined zeolite molecular sieve, cobalt salt and metal M salt is 1g:2-2.5 mmol:8-10 mmol. The mass ratio of the calcined zeolite molecular sieve to the alkaline additive is 1:6-7.

2. The alkaline additive is one or a mixture of two of urea and hexamethylenetetramine. (3) Take the CoM / zeolite molecular sieve from step (2) and calcine it in an air atmosphere in a tube furnace at 400-600℃ for 3-8 hours to obtain a catalyst based on zeolite molecular sieve.

2. The catalyst based on zeolite molecular sieve as described in claim 1, characterized in that: The zeolite molecular sieve mentioned in step (1) is one or a mixture of two or more of the following: 13X zeolite molecular sieve, ZSM-5 zeolite molecular sieve, SSZ-13 zeolite molecular sieve, KIT-6 molecular sieve, AlPO4-5 zeolite molecular sieve, NaX zeolite molecular sieve, SBA-15 molecular sieve, and MCM-41 zeolite molecular sieve.

3. The catalyst based on zeolite molecular sieve as described in claim 1, characterized in that: The cobalt salt mentioned in step (2) is one or a mixture of two of Co(NO3)2·6H2O and CoCl2·6H2O.

4. The catalyst based on zeolite molecular sieve as described in claim 1, characterized in that: The metal M salt mentioned in step (2) is one or two of Mg(NO3)2·6H2O, MgCl2, Ca(NO3)2·4H2O, and CaCl2.

5. The catalyst based on zeolite molecular sieve as described in claim 1, characterized in that: The volume of deionized water in step (2) is 60-70 mL / g based on the mass of the calcined zeolite molecular sieve.

6. The catalyst based on zeolite molecular sieve as described in claim 1, characterized in that: The separation and washing in step (2) is as follows: the reaction solution is naturally cooled at room temperature, washed sequentially with deionized water and anhydrous ethanol, and dried to obtain the CoM / zeolite molecular sieve.

7. The application of the zeolite molecular sieve-based catalyst as described in any one of claims 1-6 in the activation of persulfate degradation of organic pollutants.

8. The application as described in claim 7, characterized in that: The organic pollutant is one or more of the following: metronidazole, sulfamethoxazole, perfluorooctanoic acid, bisphenol A, norfloxacin, and tetracycline.

9. The application as described in claim 7, characterized in that... The application involves dispersing the zeolite molecular sieve-based catalyst in an aqueous solution of organic pollutants, adding persulfate, and then stirring to degrade it.

10. The application as described in claim 9, characterized in that: The concentration of organic pollutants in the aqueous solution is 10–200 mg / L; The persulfate is one or a mixture of two of permonosulfate and perdisulfate; The mass of the catalyst based on zeolite molecular sieve is 0.25–2 g / L based on the volume of the aqueous solution of the organic pollutant; The mass of the persulfate is 0.25–2 g / L based on the volume of the aqueous solution of the organic pollutant.

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