A porous ceramic catalyst and a preparation method and application thereof

Abstract

The application discloses a kind of porous ceramic catalyst and its preparation method and application, belong to porous ceramic catalyst technical field.The application uses silicon aluminum natural mineral as raw material, loads nano Co-MOF cube on its surface, and adds pore-forming agent and sintering aid, after being pressed into shape or 3D printing into shape, it is placed in inert atmosphere calcination, and the porous ceramic catalyst with micropore diameter is obtained, and good mechanical strength and high-efficiency degradation organic pollutant activity are shown.

Description

Technical Field

[0001] This invention belongs to the field of porous ceramic catalyst technology, specifically relating to a porous ceramic catalyst, its preparation method, and its application. Background Technology

[0002] In recent years, researchers have used catalysts to activate persulfate (PMS) or perdisulfate (PDS) to generate oxygen species with strong oxidizing properties to degrade antibiotics in water, demonstrating good removal effects. Among them, heterogeneous metal catalysts based on the transition metal Co have shown excellent catalytic activity. However, in order to reduce the particle size of Co metal and improve catalytic performance, Co-based catalysts are often present as powders, which has problems such as difficulty in recovery and easy secondary pollution of water bodies, thus limiting their practical application to a certain extent. CN115869980A discloses a single-atom catalytic membrane for persulfate wastewater treatment system and its preparation and application. The prepared cobalt single-atom powder is loaded onto the surface of a commercial microfiltration membrane by suction filtration, avoiding the easy loss problem of powder catalysts when directly added to the reactor, and effectively improving the problem of difficult recovery and reuse of Co metal particles.

[0003] In comparison, inorganic non-metallic materials have better heat resistance and corrosion resistance. For example, CN115385713B discloses a magnetic cobalt-iron alloy / diatomite composite ceramsite and its preparation method and application. In this invention, Fe... 3+ Co 2+ Two ions replace Na in sodium alginate + Cobalt-iron alginate microspheres were prepared, and diatomaceous earth was introduced as a carrier for the cobalt-iron particles. Diatomaceous earth ceramsite loaded with the cobalt-iron alloy was then prepared by calcination. This process can efficiently degrade antibiotics in water and facilitate magnetic recovery and reuse via an external magnetic field. Compared with ceramsite, porous ceramics have advantages such as large macroscopic size, high mechanical strength, and high-throughput reproducibility, and are widely used in filtration, separation, and catalyst support. The key to porous ceramics lies in pore size and porosity, as well as high efficiency and low cost during use. How to prepare porous ceramics with excellent mechanical properties and good crystallinity while simultaneously loading highly efficient Co catalysts remains a highly challenging problem. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a porous ceramic catalyst capable of low-temperature sintering, its preparation method, and its application. This method can prepare a highly catalytic and high-strength porous ceramic-based catalyst through a single sintering process. This catalyst can be formed into different macroscopic shapes using various molding methods. The preparation process is simple, has a short production cycle, and is flexible and easy to operate, facilitating repeated use in catalytic applications.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a porous ceramic catalyst, which is prepared by the following method:

[0007] (1) Natural mineral powder and cobalt salt are uniformly dispersed in water A to obtain mixed solution A; hexadecyltrimethylammonium bromide (CTAB) and 2-methylimidazole are uniformly dispersed in water B to obtain mixed solution B; mixed solution A is quickly poured into mixed solution B and uniformly dispersed (stirring time at room temperature is 20-40 min, preferably 30 min), and aged for 2-5 h (preferably 3 h). The resulting mixture is separated to obtain cobalt-loaded ceramic material; the mass ratio of cobalt salt to natural mineral powder is 1:1-4 (preferably 1:1.29); the molar ratio of cobalt salt, 2-methylimidazole and hexadecyltrimethylammonium bromide is 1:50-60:0.030-0.050 (preferably 1:55.29:0.041).

[0008] (2) Grind and mix the cobalt-loaded ceramic material described in step (1) with sintering aid and molding aid. After the material is shaped, place it in a protective atmosphere and calcine it for the first time at 300-400℃ for 1-2 hours (preferably calcine it for the first time at 400℃ for 1 hour). Then, raise the temperature to 950-1050℃ and calcine it for the second time for 1-3 hours (preferably calcine it for the second time at 1000℃ for 1 hour). The obtained sample is washed with deionized water and dried (dried at 60℃-80℃ for 10-12 hours) to obtain the porous ceramic catalyst.

[0009] The sintering aid is one or a mixture of low-melting-point molten salt, zeolite molecular sieve, or both. When the sintering aid contains low-melting-point molten salt, the mass ratio of the cobalt-loaded ceramic material to the low-melting-point molten salt is 1:0.125-0.5 (preferably 1:0.375); when the sintering aid contains zeolite molecular sieve, the mass ratio of the cobalt-loaded ceramic material to the zeolite molecular sieve is 1:1-4 (preferably 1:2).

[0010] The low-melting-point molten salt is a mixture of potassium and lithium salts with a molar ratio of 1:1.30-1.50 (preferably 1:1.45) and a melting point lower than the temperature of the first calcination; the molding aid contains 2-5 wt % adhesive and 0.3-1 wt An aqueous solution of surfactant; the mass ratio of the cobalt-loaded ceramic material to the molding aid is 1:0.3-3.4 (preferably 1:1).

[0011] In one embodiment of the present invention, the separation process in step (1) is as follows: the mixture is filtered, and the resulting filter cake is washed sequentially with deionized water and anhydrous ethanol (3-8 times, preferably 5 times), and dried (drying at 60-90℃, preferably 60℃) to obtain the cobalt-loaded ceramic material.

[0012] In the embodiments of the present invention, the natural mineral powder in step (1) is a powder with a particle size of 0.05μm-150μm, preferably at least one of halloysite, kaolin, feldspar, diatomite and natural zeolite (preferably halloysite and diatomite), and the cobalt salt is at least one of cobalt nitrate hexahydrate or cobalt chloride hexahydrate.

[0013] Furthermore, in step (1), the concentration of cobalt salt in the mixed solution A is 0.05-0.1 mol / L (preferably 0.08 mol / L).

[0014] Furthermore, in step (1), the concentration of 2-methylimidazole in the mixed solution B is 1-1.26 mol / L (preferably 1.16 mol / L).

[0015] In an embodiment of the present invention, the molding method described in step (2) is compression molding or 3D printing molding.

[0016] Preferably, the sintering aid in step (2) is a mixture of low-melting-point molten salt and zeolite molecular sieve. More preferably, the mass ratio of the cobalt-supported ceramic material, the low-melting-point molten salt, and the zeolite molecular sieve is 1:0.125-0.5:1-4 (preferably 1:0.375:2), and most preferably a mixture of low-melting-point molten salt and 13X molecular sieve with a mass ratio of 0.75:4. In one embodiment of the present invention, the low-melting-point molten salt is potassium chloride and lithium chloride in a molar ratio of 1:1.45. The sintering aid promotes the easy melting of materials at high temperatures to form a liquid phase and undergo liquid-phase sintering. The mixture of potassium chloride and lithium chloride has a eutectic point of 352°C.

[0017] Furthermore, the zeolite molecular sieve is at least one of 13X zeolite molecular sieve, MCM-41 zeolite molecular sieve and NaA zeolite molecular sieve (preferably 13X zeolite molecular sieve).

[0018] In one embodiment of the present invention, in step (2), the adhesive is at least one of sodium carboxymethyl cellulose and polyvinyl alcohol, the surfactant is at least one of sodium dodecyl sulfate and lithium dodecyl sulfate, and preferably the molding aid contains 3 wt % sodium carboxymethyl cellulose and 0.5 wt % aqueous solution of sodium dodecyl sulfate.

[0019] Furthermore, the protective atmosphere described in step (2) is an argon atmosphere or a nitrogen atmosphere.

[0020] The porous ceramic catalyst described herein is prepared by the following method:

[0021] (1) Natural mineral powder and cobalt salt are uniformly dispersed in water A to obtain mixed solution A; hexadecyltrimethylammonium bromide (CTAB) and 2-methylimidazole are uniformly dispersed in water B to obtain mixed solution B; mixed solution A is quickly poured into mixed solution B, uniformly dispersed, and allowed to stand for 3 hours for aging. The resulting mixture is then separated to obtain cobalt-loaded ceramic material; the mass ratio of cobalt salt to natural mineral powder is 1:1.29; the molar ratio of cobalt salt, 2-methylimidazole and hexadecyltrimethylammonium bromide is 1:55.29:0.041; the natural mineral powder is halloysite; the cobalt salt is Co(NO3)2·6H2O;

[0022] (2) Grind and mix the cobalt-loaded ceramic material described in step (1) with sintering aid and molding aid. After the material is shaped, place it in a protective atmosphere and calcine it at 400°C for the first time for 1 hour. Then, raise the temperature to 1000°C and calcine it for the second time for 1 hour. The obtained sample is washed with deionized water and dried to obtain the porous ceramic catalyst.

[0023] The sintering aid is a mixture of low-melting-point molten salt and zeolite molecular sieve, wherein the low-melting-point molten salt is a mixture of potassium chloride and lithium chloride in a molar ratio of 1:1.45; the molding aid contains 3 wt % sodium carboxymethyl cellulose and 0.5 wt An aqueous solution of sodium dodecyl sulfate; the mass ratio of the cobalt-loaded ceramic material to the molding aid is 1:1;

[0024] The mass ratio of the cobalt-loaded ceramic material to the low-melting-point molten salt is 1:0.375; the mass ratio of the cobalt-loaded ceramic material to the zeolite molecular sieve is 1:2.

[0025] Secondly, the present invention provides an application of the above-mentioned porous ceramic catalyst in the degradation of organic pollutants.

[0026] Furthermore, the organic pollutant is at least one of metronidazole, sulfamethoxazole, perfluorooctanoic acid, bisphenol A, norfloxacin, and tetracycline. In one embodiment of the present invention, the organic pollutant is metronidazole.

[0027] Specifically, the application involves placing the porous ceramic catalyst in wastewater containing organic pollutants and adding persulfate for degradation. Another application involves placing the porous ceramic catalyst in a sieve plate of a chromatography column, and then adding persulfate to the wastewater containing organic pollutants before passing it through the sieve plate for degradation.

[0028] Furthermore, the concentration of organic pollutants in the wastewater containing organic pollutants is 10-200 mg / L.

[0029] 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.

[0030] Furthermore, the ratio of the porous ceramic catalyst, persulfate, and wastewater containing organic pollutants is 0.5-4g:0.2-4g:1L.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1. The present invention can obtain ceramic crystal phases (such as mullite and sodalite) through sintering reaction, and can simultaneously support catalysts (Co metal), while also having porous characteristics.

[0033] 2. By adjusting the proportions of sintering aids and molding aids and changing the molding method, this invention can prepare porous ceramic catalysts with multi-level pore sizes and different shapes, which can meet the needs of different application environments.

[0034] 3. The porous ceramic catalyst in this invention is formed by one sintering process. While sintering the porous ceramic, a high-performance cobalt catalyst composite material supported on porous ceramic is prepared. The process is simple and the production cycle is short.

[0035] 4. This invention prepares a porous ceramic catalyst with certain macroscopic size, adjustable pore size and magnetic properties, which is easy to recycle and reuse, and solves the problem of difficult recycling during the degradation process of cobalt-containing powder catalysts.

[0036] 5. This invention adds a mixed salt of low-melting-point lithium and potassium salts as a sintering aid. The lithium-potassium salt mixture melts at 350℃-400℃ (the melting point of lithium chloride alone is 605℃, and the melting point of potassium chloride alone is 770℃. When the proportion of lithium chloride in the mixed salt of lithium and potassium salts is higher than 60 mol%, the melting point of the mixed salt is lower than 605℃, and in the proportion of this invention, it is lower than 400℃). This not only increases the fluidity between materials and improves the diffusion rate, but also reduces the sintering time and temperature of ceramics. It can also increase the porosity of porous ceramic catalysts while washing away molten salt.

[0037] 6. This invention uses artificial zeolite with low melting temperature, uniform size, high porosity, and large specific surface area as a sintering aid, which is beneficial for molding, can promote the sintering of porous ceramic catalysts, and increase porosity.

[0038] 7. This invention uses high temperature and mixed salt to transform the β cages in 13X molecular sieve from double six-membered rings to a coplanar linked structure, thereby generating sodalite with high specific surface area and excellent mechanical properties.

[0039] 8. In order to prepare porous ceramic catalysts of different sizes and with macroscopic pores, this invention adopts 3D printing direct writing process to print porous ceramic catalysts with a multi-hole network structure. The prepared three-dimensional printing slurry has high viscosity and high solid content, with a solid content of 50-62%.

[0040] 9. This invention uses water as a solvent to form 80-100nm cubic Co-MOFs through coordination of cobalt and 2-methylimidazole, which are then loaded onto silicon-aluminum materials. This makes divalent cobalt ions more stable during material processing and heat treatment, reducing the oxidation of cobalt ions. At the same time, the formed nanoscale Co-MOFs are dispersed on the surface of mineral materials, avoiding cobalt aggregation and further promoting catalytic activity.

[0041] 10. This invention uses cubic Co-MOF as a cobalt source. During the ceramic sintering process, the carbon generated by the pyrolysis of Co-MOF can reduce the cobalt in Co-MOF to form a porous ceramic cobalt-containing catalyst. The organic framework remaining after the pyrolysis of Co-MOF can increase the porosity of the porous ceramic catalyst.

[0042] 11. The porous ceramic catalyst prepared by this invention, after being sintered at high temperature and in an inert atmosphere, has high catalytic performance, and the sintered ceramic body can reduce the leaching of cobalt metal. Attached Figure Description

[0043] Figure 1 XRD patterns of the porous ceramic catalysts prepared in Examples 1 and 2: (a) Example 1, (b) Example 2.

[0044] Figure 2 SEM images of the porous ceramic catalysts prepared in Examples 2 and 4: (a) and (b) are SEM images of ZIF-67@haloysite in Example 2 at different magnifications; (c) and (d) are SEM images of the porous ceramic catalyst prepared in Example 4.

[0045] Figure 3 Photographs of the porous ceramic catalysts prepared in Examples 1, 2, 3, 4 and Comparative Examples 1 and 2: (a) Example 2, (b) Example 4, (c) Comparative Example 1, (d) Comparative Example 2, (e) Example 3, (f) Example 1.

[0046] Figure 4Photographs of the magnetic properties of the porous ceramic catalysts prepared in Examples 1 and 2: (a) Example 2, (b) Example 1.

[0047] Figure 5 Photographs of the porous ceramic catalysts prepared in Example 7, Comparative Example 3, and Example 8: (a) Example 7, (b) Comparative Example 3, (c) Example 8. Figure 5 As can be seen in Comparative Example 3, the sintering and forming were poor (i.e., the ceramic body was broken).

[0048] Figure 6 This is a photograph of the porous ceramic catalyst prepared in Example 1 being applied to water degradation.

[0049] Figure 7 Images of the porous ceramic catalyst prepared in Example 5 before and after calcination in the 3D printing direct writing process: (a) before calcination, (b) after calcination. Detailed Implementation

[0050] Example 1

[0051] (1) Place 1.5g halloysite (particle size 0.05μm-50μm) in 50mL of water and sonicate for 20min. Add 1.164g Co(NO3)2·6H2O and sonicate for 10min to obtain mixed solution A.

[0052] (2) Dissolve 18.16g of 2-methylimidazole and 0.060g of CTAB in 190mL of water to obtain mixed solution B. Pour solution A into solution B, stir at room temperature for 30min, age for 3h, filter the suspension, wash with deionized water and anhydrous ethanol in sequence, and vacuum dry at 60℃ overnight to obtain ZIF-67@halolite.

[0053] (3) Weigh 1.212g KCl and 1g LiCl into an agate mortar, mix and grind thoroughly to obtain mixed molten salt A.

[0054] (4) Take 0.2g ZIF-67@halolite, 0.4g 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) and 0.075g molten salt A, add 0.2g aqueous solution containing 3wt% sodium carboxymethyl cellulose and 0.5wt% sodium dodecyl sulfate, grind and mix in a mortar, pour the mixed material into a small crucible, press it flat, place it in a nitrogen atmosphere at 400℃ for 1h, raise the temperature to 1000℃ and continue calcining for 1h, cool naturally in a tube furnace, wash with deionized water, and vacuum dry overnight at 60℃ to obtain composite material A.

[0055] Example 2

[0056] (1) Place 4.5g halloysite (particle size 0.05μm-50μm) in 50mL of water and sonicate for 20min. Add 1.164g Co(NO3)2·6H2O and sonicate for 10min to obtain mixed solution A.

[0057] (2) Dissolve 18.16g of 2-methylimidazole and 0.060g of CTAB in 190mL of water to obtain mixed solution B. Pour solution A into solution B, stir at room temperature for 30min, age for 3h, filter the suspension, wash with deionized water and anhydrous ethanol in sequence, and vacuum dry at 60℃ overnight to obtain ZIF-67@halolite.

[0058] (3) ZIF-67@diatomite was prepared by using the methods in steps (1) and (2), only halloysite was replaced with diatomite (particle size 1μm-150μm).

[0059] (4) Weigh 1.212g KCl and 1g LiCl into an agate mortar, mix and grind thoroughly to obtain mixed molten salt A.

[0060] (5) Take 0.4g ZIF-67@halolite, 0.2g ZIF-67@diatomite and 0.075g molten salt A, add 0.2g of aqueous solution containing 3wt% sodium carboxymethyl cellulose and 0.5wt% sodium dodecyl sulfate, grind and mix in a mortar, pour the mixed material into a small crucible, press it flat, place it in a nitrogen atmosphere at 400℃ for 1h, raise the temperature to 1000℃ and continue calcining for 1h, cool naturally in a tube furnace, wash with deionized water, and vacuum dry overnight at 60℃ to obtain composite material B.

[0061] Example 3

[0062] (1) Place 4.5g halloysite (particle size 0.05μm-50μm) in 50mL of water and sonicate for 20min. Add 1.164g Co(NO3)2·6H2O and sonicate for 10min to obtain mixed solution A.

[0063] (2) Dissolve 18.16g of 2-methylimidazole and 0.060g of CTAB in 190mL of water to obtain mixed solution B. Pour solution A into solution B, stir at room temperature for 30min, age for 3h, filter the suspension, wash with deionized water and anhydrous ethanol in sequence, and vacuum dry at 60℃ overnight to obtain ZIF-67@halolite.

[0064] (3) ZIF-67@diatomite can be prepared by using the methods in steps (1) and (2), only the halloysite needs to be replaced with diatomite (particle size 1μm-150μm).

[0065] (4) Weigh 1.212g KCl and 1g LiCl into an agate mortar, mix and grind thoroughly to obtain mixed molten salt A.

[0066] (5) Take 0.4g ZIF-67@halolite, 0.2g ZIF-67@diatomite and 0.150g molten salt A, grind and mix them in a mortar, add 0.2g of aqueous solution containing 3wt% sodium carboxymethyl cellulose and 0.5wt% sodium dodecyl sulfate, pour the mixed material into a small crucible, press it flat, calcine it at 400℃ in a nitrogen atmosphere for 1h, raise the temperature to 1000℃ and continue calcining for 1h, cool it naturally in a tube furnace, wash it with deionized water, and vacuum dry it overnight at 60℃ to obtain composite material C.

[0067] Example 4

[0068] (1) Place 4.5g halloysite (particle size 0.05μm-50μm) in 50mL of water and sonicate for 20min. Add 1.164g Co(NO3)2·6H2O and sonicate for 10min to obtain mixed solution A.

[0069] (2) Dissolve 18.16g of 2-methylimidazole and 0.060g of CTAB in 190mL of water to obtain mixed solution B. Pour solution A into solution B, stir at room temperature for 30min, age for 3h, filter the suspension, wash with deionized water and anhydrous ethanol in sequence, and vacuum dry at 60℃ overnight to obtain ZIF-67@halolite.

[0070] (3) ZIF-67@diatomite can be prepared by using the methods in steps (1) and (2), only the halloysite needs to be replaced with diatomite (particle size 1μm-150μm).

[0071] (4) Weigh 1.212g KCl and 1g LiCl into an agate mortar, mix and grind thoroughly to obtain mixed molten salt A.

[0072] (5) Take 0.4g ZIF-67@halolite, 0.2g ZIF-67@diatomite and 0.3g molten salt A, add 0.2g of aqueous solution containing 3wt% sodium carboxymethyl cellulose and 0.5wt% sodium dodecyl sulfate, grind and mix in a mortar, pour the mixed material into a small crucible, press it flat, place it in a nitrogen atmosphere at 400℃ for 1h, raise the temperature to 1000℃ and continue calcining for 1h, cool naturally in a tube furnace, wash with deionized water, and vacuum dry overnight at 60℃ to obtain composite material D.

[0073] Example 5

[0074] (1) Place 1.5g of diatomaceous earth (particle size 1μm-150μm) in 50mL of water and sonicate for 20min. Add 1.164g of Co(NO3)2·6H2O and sonicate for 10min to obtain mixed solution A.

[0075] (2) Dissolve 18.16g of 2-methylimidazole and 0.060g of CTAB in 190mL of water to obtain mixed solution B. Pour solution A into solution B, stir at room temperature for 30min, age for 3h, filter the suspension, wash with deionized water and anhydrous ethanol in sequence, and vacuum dry at 60℃ overnight to obtain ZIF-67@diatomite.

[0076] (3) Weigh 1.212g KCl and 1g LiCl into an agate mortar, mix and grind thoroughly to obtain mixed molten salt A.

[0077] (4) Take 0.75g ZIF-67@diatomaceous earth, 3g 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) and 0.375g mixed molten salt A, and add 2.5g of a solution containing 3 wt % sodium carboxymethyl cellulose and 0.5 wt A % sodium dodecyl sulfate aqueous solution was ground and mixed in a mortar. The mixed slurry was extruded into a syringe and dried overnight in a vacuum drying oven at 60°C. The sample was then calcined at 400°C for 1 hour in a nitrogen atmosphere, and the temperature was increased to 1000°C for another hour. The sample was then naturally cooled in a tube furnace, washed with deionized water, and dried overnight in a vacuum oven at 60°C to obtain composite material E.

[0078] Example 6

[0079] (1) Place 4.5g of diatomaceous earth (particle size 1μm-150μm) in 50mL of water and sonicate for 20min. Add 1.164g of Co(NO3)2·6H2O and sonicate for 10min to obtain mixed solution A.

[0080] (2) Dissolve 18.16g of 2-methylimidazole and 0.060g of CTAB in 190mL of water to obtain mixed solution B. Pour solution A into solution B, stir at room temperature for 30min, age for 3h, filter the suspension, wash with deionized water and anhydrous ethanol in sequence, and vacuum dry at 60℃ overnight to obtain ZIF-67@diatomite.

[0081] (3) Weigh 1.212g KCl and 1g LiCl into an agate mortar, mix and grind thoroughly to obtain mixed molten salt A.

[0082] (4) Take 0.5g ZIF-67@diatomaceous earth, 2g 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm) and 0.25g molten salt A, and add 1.5g of a solution containing 3 wt % Polyvinyl alcohol 0.5 wt A % sodium dodecyl sulfate aqueous solution was ground and mixed in a mortar. The mixed slurry was extruded into a syringe and dried overnight in a vacuum drying oven at 60°C. The sample was then calcined at 400°C for 1 hour in a nitrogen atmosphere, and the temperature was increased to 1000°C for another hour. The sample was then naturally cooled in a tube furnace, washed with deionized water, and dried overnight in a vacuum oven at 60°C to obtain composite material F.

[0083] Example 7

[0084] (1) Place 1.5g halloysite (particle size 0.05μm-50μm) in 50mL of water and sonicate for 20min. Add 1.164g Co(NO3)2·6H2O and sonicate for 10min to obtain mixed solution A.

[0085] (2) Dissolve 18.16g of 2-methylimidazole and 0.060g of CTAB in 190mL of water to obtain mixed solution B. Pour solution A into solution B, stir at room temperature for 30min, age for 3h, filter, wash and dry. Filter the suspension, wash it with deionized water and anhydrous ethanol in sequence, and vacuum dry it overnight at 60℃ to obtain ZIF-67@halolite.

[0086] (3) Weigh 1.212g KCl and 1g LiCl into an agate mortar, mix and grind thoroughly to obtain mixed molten salt A.

[0087] (4) Take 0.6g ZIF-67@halolite and 0.075g molten salt A, add 0.2g of aqueous solution containing 3wt% sodium carboxymethyl cellulose and 0.5wt% sodium dodecyl sulfate, grind and mix in a mortar, pour the mixed material into a small crucible, press it flat, place it in a nitrogen atmosphere at 400℃ for 1h, raise the temperature to 1000℃ and continue calcining for 1h, cool it naturally in a tube furnace, wash it with deionized water, and vacuum dry it overnight at 60℃ to obtain composite material G.

[0088] Example 8

[0089] (1) Place 1.5g halloysite (particle size 0.05μm-50μm) in 50mL of water and sonicate for 20min. Add 1.164g Co(NO3)2·6H2O and sonicate for 10min to obtain mixed solution A.

[0090] (2) Dissolve 18.16g of 2-methylimidazole and 0.060g of CTAB in 190mL of water to obtain mixed solution B. Pour solution A into solution B, stir at room temperature for 30min, age for 3h, filter the suspension, wash with deionized water and anhydrous ethanol in sequence, and vacuum dry at 60℃ overnight to obtain ZIF-67@halolite.

[0091] (3) Take 0.2g ZIF-67@halolite and 0.4g 13X molecular sieve (manufacturer: Tianjin Nanhua Catalyst Co., Ltd., model: 13X, particle size 0.5μm-50μm), add 0.2g of aqueous solution containing 3wt% sodium carboxymethyl cellulose and 0.5wt% sodium dodecyl sulfate, grind and mix in a mortar, pour the mixed material into a small crucible, press it flat, place it in a nitrogen atmosphere at 400℃ for 1h, raise the temperature to 1000℃ and continue calcining for 1h, cool naturally in a tube furnace, wash with deionized water, and vacuum dry overnight at 60℃ to obtain composite material H.

[0092] Comparative Example 1

[0093] (1) Place 4.5g halloysite (particle size 0.05μm-50μm) in 50mL of water and sonicate for 20min. Add 1.164g Co(NO3)2·6H2O and sonicate for 10min to obtain mixed solution A.

[0094] (2) Dissolve 18.16g of 2-methylimidazole and 0.060g of CTAB in 190mL of water to obtain mixed solution B. Pour solution A into solution B, stir at room temperature for 30min, age for 3h, filter the suspension, wash with deionized water and anhydrous ethanol in sequence, and vacuum dry at 60℃ overnight to obtain ZIF-67@halolite.

[0095] (3) ZIF-67@diatomite can be prepared by using the methods in steps (1) and (2), only the halloysite needs to be replaced with diatomite (particle size 1μm-150μm).

[0096] (4) Take 0.4g of ZIF-67@halolite and 0.2g of ZIF-67@diatomite, and add 0.2g of a solution containing 3 wt % sodium carboxymethyl cellulose and 0.5 wt A % sodium dodecyl sulfate aqueous solution was ground and mixed in a mortar. The mixture was then poured into a small crucible, pressed flat, and calcined at 400°C for 1 hour under a nitrogen atmosphere. The temperature was then increased to 1000°C and calcined for another hour. The mixture was then naturally cooled in a tube furnace, washed with deionized water, and vacuum dried overnight at 60°C to obtain the sample of Comparative Example 1.

[0097] Comparative Example 2

[0098] (1) Place 4.5g halloysite (particle size 0.05μm-50μm) in 50mL of water and sonicate for 20min. Add 1.164g Co(NO3)2·6H2O and sonicate for 10min to obtain mixed solution A.

[0099] (2) Dissolve 18.16g of 2-methylimidazole and 0.060g of CTAB in 190mL of water to obtain mixed solution B. Pour solution A into solution B, stir at room temperature for 30min, age for 3h, filter the suspension, wash with deionized water and anhydrous ethanol in sequence, and vacuum dry at 60℃ overnight to obtain ZIF-67@halolite.

[0100] (3) ZIF-67@diatomite can be prepared by using the methods in steps (1) and (2), only the halloysite needs to be replaced with diatomite (particle size 1μm-150μm).

[0101] (4) Weigh 1g KCl and 1.96g ZnCl2 and place them in an agate mortar. Mix and grind them thoroughly to obtain mixed molten salt B (eutectic point is 228℃).

[0102] (5) Take 0.4g ZIF-67@halolite, 0.2g ZIF-67@diatomite and 0.3g molten salt B, add 0.2g of aqueous solution containing 3wt% sodium carboxymethyl cellulose and 0.5wt% sodium dodecyl sulfate, grind and mix in a mortar, pour the mixed material into a small crucible, press it flat, place it in a nitrogen atmosphere at 400℃ for 1h, raise the temperature to 1000℃ and continue calcining for 1h, cool naturally in a tube furnace, wash with deionized water, and vacuum dry overnight at 60℃ to obtain the sample of Comparative Example 2.

[0103] Comparative Example 3

[0104] (1) Place 1.5g halloysite in 50mL of water and sonicate for 20min. Add 1.164g Co(NO3)2·6H2O and sonicate for 10min to obtain mixed solution A.

[0105] (2) Dissolve 18.16g of 2-methylimidazole and 0.060g of CTAB in 190mL of water to obtain mixed solution B. Pour solution A into solution B, stir at room temperature for 30min, age for 3h, filter the suspension, wash with deionized water and anhydrous ethanol in sequence, and vacuum dry at 60℃ overnight to obtain ZIF-67@halolite.

[0106] (3) Take 0.6g of ZIF-67@halolite, add 0.2g of aqueous solution containing 3wt% sodium carboxymethyl cellulose and 0.5wt% sodium dodecyl sulfate, grind and mix in a mortar, pour the mixed material into a small crucible, press it flat, calcine it at 400℃ in a nitrogen atmosphere for 1h, raise the temperature to 1000℃ and continue calcining for 1h, cool it naturally in a tube furnace, wash it with deionized water, and vacuum dry it overnight at 60℃ to obtain the sample of Comparative Example 3.

[0107] Application Comparison Experiment

[0108] A 20 mg / L metronidazole solution was prepared to simulate organic pollutants. 0.025 g of samples from Examples 1-8 and Comparative Examples 1-2 were placed in 50 mL of metronidazole solution, and 0.025 g of potassium persulfate was added. Small amounts of solution were taken for solid-liquid separation at 5 min, 10 min, and 30 min after the reaction. The concentration of residual metronidazole in the solution was measured using a UV spectrophotometer, and the degradation rate of metronidazole by the samples was calculated, as shown in Table 1.

[0109] Table 1

[0110]

[0111] Methods for judging the mechanical properties of samples:

[0112] (1) Determine if the sample is ceramic: make the sample fall freely from a height of 30cm and see if there is a crisp sound when it lands.

[0113] (2) Determine the mechanical properties of the sample: make the sample fall freely from a height of 30cm and determine whether the sample breaks or cracks.

[0114] The test results are shown in Table 2.

[0115] Table 2

[0116]

[0117] The density and porosity of samples from Examples 1-4, 7, and 8 were measured using Archimedes' principle.

[0118] First, measure the mass D of the sample in the dry state in air. Then, heat the material block in water at 80°C for 5 hours and cool it in water for 24 hours. Measure its wet mass W in air and its wet mass S suspended in water.

[0119] The measured data were calculated using the following formula, and the calculation results are shown in Table 3.

[0120] Volume of the impermeable material: V1 = (D - S) / d; Volume of the permeable part: V2 = (W - D) / d

[0121] Apparent volume: V = V1 + V2 = (W - S) / d

[0122] Bulk density: B = D / V

[0123] Apparent porosity: P = V² / V

[0124] Apparent weight: T = D / V1

[0125] Water absorption rate: A = (W - D) / D

[0126] Table 3

[0127]

[0128] Where d is the density of water and S is the weight of the sample in water.

[0129] 1. As can be seen from Examples 1-8 and Comparative Examples 1-2 in Table 1, the porous ceramic catalyst has excellent catalytic performance. Among them, Examples 1 and 5 can achieve a catalytic degradation of metronidazole of more than 97% in 5 minutes, showing a rapid and efficient catalytic degradation effect.

[0130] 2. By comparing the mechanical strength of Examples 2, 3, and 4 and Comparative Examples 1 and 2 in Table 2, it can be shown that the addition of an appropriate amount of low-melting-point lithium-potassium salt mixed salt as a sintering aid can improve the mechanical strength of porous ceramic catalysts.

[0131] 3. Through Examples 1, 2, 3, 4, 7 and 8 in Table 3, it can be shown that the porous ceramic catalyst prepared by the present invention has a high porosity.

[0132] 4. By comparing Examples 1, 7 and 8 in Table 1, it can be shown that the addition of low-melting-point zeolite molecular sieves can improve the degradation performance of porous ceramic catalysts.

[0133] 5. By comparing the mechanical strength of Examples 1, 7 and Comparative Example 3 in Table 2, it can be shown that the simultaneous addition of low-melting-point lithium-potassium salt mixed salt and low-melting-point zeolite molecular sieve can improve the mechanical properties of porous ceramic catalysts.

[0134] Image caption

[0135] Figure 1 XRD patterns of the porous ceramic catalysts prepared in Examples 1 and 2; Figure 1The XRD images show that the peaks at 44.2°, 51.5°, and 75.9° correspond to the (111), (200), and (220) crystal planes of Co, respectively; the peaks at 16.4°, 26.2°, 33.1°, 35.2°, 40.8°, and 60.7° correspond to the (110), (210), (220), (111), (121), and (430) crystal planes of mullite, respectively; and the peaks at 14.3°, 20.3°, 24.9°, 38.5°, and 59.8° correspond to the (110), (200), (211), (321), and (440) crystal planes of sodalite, respectively. This indicates that the present invention has successfully prepared a porous ceramic catalyst with high catalytic performance in the cobalt, mullite, and sodalite phases.

[0136] Figure 2 SEM images of the porous ceramic catalysts prepared in Examples 2 and 4; Figure 2 As can be seen in (a) and (b), 80-100 nm Co-MOF cubes are dispersed on the surface of the rod-shaped halloysite, indicating that the nanoscale cobalt catalyst can be well dispersed in the ceramic material, avoiding metal agglomeration and making it more conducive to the reaction activity of the catalyst.

[0137] Figure 3 Photographs of the porous ceramic catalysts prepared in Examples 1, 2, 3, 4 and Comparative Examples 1 and 2: It can be seen that... Figure 3 (c) The porous ceramic catalyst in Comparative Example 1 was broken, indicating that the absence of molten salt would result in poor mechanical strength.

[0138] Figure 4 These are photographs showing the magnetic properties of the porous ceramic catalysts prepared in Examples 1 and 2. Figure 4 This indicates that porous ceramics have a certain ability to be attracted by magnets, and magnets can be used for recycling in applications.

[0139] Figure 5 The images show photographs of the porous ceramic catalysts prepared in Examples 7, 3, and 8. The porous ceramic catalyst in Comparative Example 3 is broken, indicating that the mechanical properties of the porous ceramic catalyst will be reduced if sintering aids (low-melting-point molten salts or low-melting-point zeolite molecular sieves) are not added.

[0140] Figure 6 The photograph shows the application of the porous ceramic catalyst prepared in Example 1 in water degradation, which illustrates that the porous ceramic catalyst prepared by the present invention is easy to recycle and reuse.

[0141] Figure 7The images shown are of the porous ceramic catalyst prepared in Example 5 before and after calcination by direct writing. This illustrates that the slurry catalyst prepared by the present invention can be directly written using 3D printing, and has the advantage of adjustable pore size during the preparation of porous ceramic catalysts.

Claims

1. A porous ceramic catalyst, characterized in that... The porous ceramic catalyst is prepared according to the following method: (1) Natural mineral powder and cobalt salt are uniformly dispersed in water to obtain mixed solution A; hexadecyltrimethylammonium bromide and 2-methylimidazole are uniformly dispersed in water to obtain mixed solution B; mixed solution A is poured into mixed solution B, uniformly dispersed, and allowed to stand for 2-5 hours for aging; the resulting mixture is separated to obtain cobalt-loaded ceramic material; the mass ratio of cobalt salt to natural mineral powder is 1:1-4; the molar ratio of cobalt salt, 2-methylimidazole and hexadecyltrimethylammonium bromide is 1:50-60:0.030-0.050; (2) Grind and mix the cobalt-loaded ceramic material described in step (1) with sintering aid and molding aid. After the material is shaped, place it in a protective atmosphere and calcine it for the first time at 300-400℃ for 1-2 hours. Then, raise the temperature to 950-1050℃ and calcine it for the second time for 1-3 hours. The obtained sample is washed with deionized water and dried to obtain the porous ceramic catalyst. The sintering aid is a mixture of low-melting-point molten salt and zeolite molecular sieve; the zeolite molecular sieve is 13X zeolite molecular sieve. The mass ratio of the cobalt-loaded ceramic material, the low-melting-point molten salt, and the zeolite molecular sieve is 1:0.125-0.5:1-4. The low-melting-point molten salt is a mixture of potassium and lithium salts with a molar ratio of 1:1.30-1.50, whose melting point is lower than the temperature of the first calcination; the molding aid contains 2-5 wt % adhesive and 0.3-1 wt An aqueous solution of surfactant; the mass ratio of the cobalt-loaded ceramic material to the molding aid is 1:0.3-3.

4.

2. The porous ceramic catalyst as described in claim 1, characterized in that: The separation process in step (1) is as follows: the mixture is filtered, the resulting filter cake is washed with deionized water and anhydrous ethanol in sequence, and dried to obtain the cobalt-loaded ceramic material.

3. The porous ceramic catalyst as described in claim 1, characterized in that: The natural mineral powder mentioned in step (1) is a powder with a particle size of 0.05μm-150μm, and is at least one of halloysite, kaolin, feldspar, diatomite and natural zeolite.

4. The porous ceramic catalyst as described in claim 1, characterized in that: The cobalt salt mentioned in step (1) is at least one of cobalt nitrate hexahydrate or cobalt chloride hexahydrate; the concentration of the cobalt salt in the mixed solution A is 0.05-0.1 mol / L; the concentration of 2-methylimidazole in the mixed solution B is 1-1.26 mol / L.

5. The porous ceramic catalyst as described in claim 1, characterized in that: The molding method described in step (2) is compression molding or 3D printing molding.

6. The porous ceramic catalyst according to claim 1, characterized in that: The adhesive in step (2) is at least one of sodium carboxymethyl cellulose and polyvinyl alcohol, and the surfactant is at least one of sodium dodecyl sulfate and lithium dodecyl sulfate; the protective atmosphere is an argon atmosphere or a nitrogen atmosphere.

7. The application of the porous ceramic catalyst as described in claim 1 in the degradation of organic pollutants.

8. The application as described in claim 7, characterized in that... The organic pollutant is at least one of metronidazole, sulfamethoxazole, perfluorooctanoic acid, bisphenol A, norfloxacin, and tetracycline.

9. The application as described in claim 8, characterized in that: The application involves placing the porous ceramic catalyst in wastewater containing organic pollutants and adding persulfate for degradation. The concentration of organic pollutants in the wastewater containing organic pollutants is 10-200 mg / L; The persulfate is one or a mixture of two of permonosulfate and perdisulfate; The ratio of the porous ceramic catalyst, persulfate, and wastewater containing organic pollutants is 0.5-4g:0.2-4g:1L.

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