Preparation method of foamed ceramic-metal organic framework composite catalytic material and application of foamed ceramic-metal organic framework composite catalytic material in photo-thermal catalytic elimination of nitro compound

Abstract

The invention belongs to the technical field of optical drive catalytic materials, and discloses a preparation method of a foamed ceramic-metal organic framework composite catalytic material and application of the foamed ceramic-metal organic framework composite catalytic material in photo-thermal catalytic elimination of nitro compounds. According to the invention, photo-thermal catalytic MOFs are loaded on foamed ceramic, and a floatable integrated photocatalytic material is formed through in-situ self-assembly and is used for solar-driven nitro-compound thermal elimination. MOFs have high specific surface area, high porosity, good light absorption and high photo-thermal conversion efficiency; the foamed ceramic has the characteristics of strong adsorbability, good heat conduction, light weight, adjustable size and the like. The combination of the two overcomes the problems of difficult recovery, more residues and low efficiency of the traditional powder catalyst and the high cost, high energy consumption, high-temperature danger and the like of the traditional photo-thermal catalysis, and shows huge application potential. The method can be used for treating organic wastewater containing toxic nitro compounds (such as trinitrotoluene, dinitrobenzene, nitrochlorobenzene and the like), and a new thought is provided for wastewater treatment in the fields of explosives, medicines, pesticides, dyes and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalytic materials, and relates to a foam ceramic-metal organic framework composite catalytic material, as well as the extension of different transition metal centers and different organic ligands. Background Art

[0002] Nitro compounds are important industrial raw materials, widely used in fields such as explosives, pharmaceuticals, dyes, and agriculture. They also widely exist in the wastewater of these fields, such as 4-nitrophenol, nitrobenzoic acid, p- and o-nitrochlorobenzene in pharmaceutical wastewater and pesticide wastewater, and 2-nitrotoluene, 2,4-dinitrotoluene in dye wastewater. Using sunlight to drive the elimination of nitro compounds in wastewater can not only remove pollutants but also produce more valuable amino compound products. The reduction products of nitro compounds are diverse, including nitroso compounds, azobenzene compounds, amino compounds, etc. Amino compounds are important intermediates for many drugs, can be used to synthesize antibacterial drugs, anesthetic drugs, etc., and have functions such as relieving asthma and treating cardiovascular diseases. And industrially, amino compounds are mainly prepared by reducing nitro compounds. The traditional thermal catalytic reduction method has very high energy consumption, high cost, difficult raw material recovery, and produces a large amount of toxic solid waste and organic wastewater, exacerbating environmental pollution problems. However, sustainable development puts forward requirements for recyclability and high selectivity of catalytic materials for the hydrogenation reaction of nitro compounds. Reducing nitro compounds to amino compounds helps reduce their harm to the environment and at the same time provides an important organic compound, aromatic amino compounds, which is in line with the development trend of modern green chemistry.

[0003] Industrially, iron powder and strong acid are usually used as catalysts and reducing agents to reduce nitro compounds. Although this method is simple to operate and low in cost, it will produce other pollutants, the catalyst is difficult to recycle, and a large amount of toxic by-products and strong acid wastewater are generated, exacerbating environmental pollution problems. Or at high temperatures (150 - 300 °C), noble metal (palladium, platinum, gold, silver, etc.) catalysts are used, and hydrogen at high pressure or normal pressure is used as a reducing agent to reduce nitro compounds. This method has high product purity and good selectivity, but the equipment investment and operation cost are relatively high, and the operation steps are difficult and dangerous. The above methods are not suitable for purifying a large amount of organic wastewater and cannot eliminate nitro compounds in wastewater in large quantities. Therefore, it is urgent to find a catalytic material with high efficiency, high light-to-heat conversion efficiency, recyclability, and environmental friendliness. Summary of the Invention

[0004] Based on the previous research, in response to the demand for efficient and environmentally friendly treatment of toxic nitro compounds, a foam ceramic-metal organic framework (MOFs) composite catalytic material was prepared. This material uses porous MOFs formed by the self-assembly of different metal salts and organic ligands as the active component, combined with foam ceramics such as alumina, zirconia, and silicon carbide with pore sizes of 2-50 nm as the carrier. By in-situ self-assembly synthesis of MOFs and using the in-situ physical mixing and stirring method to uniformly load it into the pores of the foam ceramic, the dispersibility of MOFs and the bonding strength with the substrate are significantly improved, ensuring its stability and durability under harsh conditions. The present invention utilizes the photothermal effect of MOFs, the strong adsorption of foam ceramics, and the reducibility of hydrazine hydrate. Using an aqueous solution of nitro compounds to simulate organic wastewater containing nitro compounds, the efficient catalytic conversion of nitro compounds is achieved under sunlight drive without additional heating, and the conditions are safe and controllable. The preparation method of this composite catalytic material is simple, has low equipment requirements, and high yield. It can large-scale reduce nitro compounds to aromatic amino compounds, which has important theoretical significance and practical value for realizing the efficient and environmentally friendly conversion of nitro compounds and meets the requirements of national sustainable development.

[0005] The preparation method of the foam ceramic-metal organic framework composite catalytic material of the present invention is as follows:

[0006] (1) Preparation of single metal organic framework (MOFs):

[0007] Dissolve the organic ligand and soluble metal salt in N,N'-dimethylformamide solution in proportion, and add acetonitrile, deionized water, and concentrated hydrochloric acid in proportion and mix well at room temperature; hydrothermal treatment at 80-200 °C for 48 h, centrifuge to separate the product into green transparent block crystals, wash several times with ethanol, and dry in vacuum to obtain the single metal MOFs material, named M-MOFs.

[0008] The organic ligand includes one of phenylpropionyl imide phenanthroline tetracarboxylic acid (PDI), 5-aminoisophthalic acid (AIPA), 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), or tetrakis(4-carboxyphenyl)porphine (TCPP);

[0009] The soluble metal salt includes one of CuCl2·3H2O, FeCI3·6H2O, NiCl2·6H2O, CeCl3, Mn(NO2)2, and Zn(NO2)2.

[0010] The molar ratio of the organic ligand to the soluble metal salt is 1:1; the molar ratio of the added acetonitrile, deionized water, concentrated hydrochloric acid to the organic ligand is 20:56:0.5:1.

[0011] (2) Preparation of bimetallic center MOFs:

[0012] Dissolve the organic ligand, soluble metal salt 1 and soluble metal salt 2 proportionally in an N,N'-dimethylformamide solution, add acetonitrile, deionized water and concentrated hydrochloric acid and mix them, and stir evenly at room temperature; hydrothermal react at 80 - 200 °C for 48 h, centrifuge to separate the product into green transparent block crystals, wash several times with ethanol, and dry in vacuum to obtain a bimetallic MOFs material, named MM-MOFs.

[0013] The organic ligand includes one of phenylpropionyl imide phenanthroline tetracarboxylic acid (PDI), 5-aminoisophthalic acid (AIPA), 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) or tetrakis(4-carboxyphenyl)porphine (TCPP);

[0014] The soluble metal salt 1 and soluble metal salt 2 include any two of CuCl2·3H2O, FeCI3·6H2O, NiCl2·6H2O, CeCl3, Mn(NO2)2 and Zn(NO2)2.

[0015] The molar ratio of the organic ligand, soluble metal salt 1 and soluble metal salt 2 is 2:1:1; the molar ratio of the added acetonitrile, deionized water, concentrated hydrochloric acid to the organic ligand is 20:56:0.5:1.

[0016] (3) Preparation of the solid-supported device:

[0017] Add the M-MOFs obtained in step (1) or the MM-MOFs obtained in step (2) and alumina, SiC or ZrO2 foam ceramics into DMF respectively, and fully ultrasonic vibrate and stir to make the MOFs material fully supported on the porous foam ceramics to obtain a foam ceramic - metal-organic framework composite catalytic material, named M-MOFs@AlC, M-MOFs@SiC, M-MOFs@Zr or MM-MOFs@AlC, MM-MOFs@SiC, MM-MOFs.

[0018] The shape and size of the foam ceramics are flat cylindrical, spherical or cubic, and the pore diameter is 2 - 50 nm. The dosage of M-MOFs or MM-MOFs is: add 1 g of M-MOFs or MM-MOFs to each 1 dm 3 of foam ceramics.

[0019] Use the solid-supported device prepared by the present invention for the use of photocatalytic elimination of nitro compounds in water bodies, and the steps are as follows:

[0020] String together 3-4 of the solid-supported devices obtained in the above step (3) with a rope. Under an air atmosphere, add them to a reaction vessel containing a mixed solution of a nitro compound and a reducing agent. Under the conditions of sunlight or simulated sunlight illumination with a 300 W Xe lamp, degrade and convert the nitro compound into an aromatic amino compound. Centrifuge the reaction mixture, take the supernatant, and obtain the product content by gas chromatography rapid chromatography and record the data.

[0021] The nitro compound is trinitrotoluene, dinitrobenzene, nitrochlorobenzene, nitrophenol, or halogenated nitrobenzene.

[0022] The reducing agent is one of hydrazine hydrate, sodium borohydride, and borane ammonia.

[0023] When the reducing agent is hydrazine hydrate, the molar ratio of the nitro compound to hydrazine hydrate is 1:10;

[0024] When the reducing agent is sodium borohydride, the molar ratio of the nitro compound to sodium borohydride is 1:6;

[0025] When the reducing agent is borane ammonia, the molar ratio of the nitro compound to borane ammonia is 1:4;

[0026] Recovery of the composite catalytic material: Just lift the rope to recover the catalytic material. It can be dried in an oven and stored in a brown glass bottle for recycling in the next reaction.

[0027] The beneficial effects of the present invention are as follows:

[0028] (1) Using a foam ceramic material as the catalytic support and uniformly loading MOFs in the pore structure of the foam ceramic improves the dispersion of MOFs and ensures the adsorption capacity of the MOFs material under harsh conditions.

[0029] (2) The yield of the reaction driven by the method of the present invention is relatively high, and the degradation conversion rate can reach 95%.

[0030] (3) The catalyst used is a metal-organic framework (MOFs), which avoids the use of precious metal catalysts and reduces the cost of the reaction.

[0031] (4) Utilizing photo-driven thermal catalysis, the reaction can be driven only by light, reducing energy consumption and conforming to the development trend of modern green chemistry.

[0032] (5) The reducing agents used in the method of the present invention are hydrazine hydrate, sodium borohydride, and borane ammonia, avoiding the use of high-pressure hydrogen and making the experimental conditions safer. Description of the Drawings

[0033] Figure 1 They are foam ceramics of different shapes and sizes;

[0034] Figure 2 is the structural formula of the MOF organic ligand;

[0035] Figure 3 are the XRD pattern (a) and FTIR spectrum (b) of the Cu-based MOF;

[0036] Figure 4 is the SEM image of the Cu-based MOF;

[0037] Figure 5 is a schematic diagram of the foam ceramic supported MOF and the photothermal catalytic elimination of nitro compounds in water. Detailed implementation manners

[0038] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in combination with experimental data and implementation examples. It should be understood that the specific implementation examples described herein are only used to explain the present invention and are not used to limit the present invention. Moreover, the raw materials used are widely sourced and can be industrially produced. At the same time, the reagents used in the examples are all commercially available.

[0039] Example 1

[0040] A method for preparing a foam ceramic-metal organic framework composite catalytic material and its photothermal catalytic elimination of nitro compounds, the specific steps are as follows:

[0041] (1) Preparation of Cu-PDI material:

[0042] ① Dissolve the phthalimide phenanthroline tetracarboxylic acid (PDI) ligand and copper nitrate trihydrate with a molar ratio of 1:1 in a glass bottle in an appropriate amount of N,N'-dimethylformamide solution, and add a small amount of acetonitrile, deionized water and concentrated hydrochloric acid and mix them. The molar ratio of the added acetonitrile, deionized water and concentrated hydrochloric acid to the organic ligand is 20:56:0.5:1, and stir evenly at room temperature.

[0043] ② Place the glass bottle in an oven and hydrothermally treat it at 80 °C for 48 h.

[0044] ③ Centrifuge to separate the product into green transparent block crystals, wash them several times with ethanol, and dry them in vacuum. Obtain the Cu-based MOF material, named Cu-PDI.

[0045] (2) Preparation of Cu-PDI@AlC:

[0046] Put an appropriate amount of Cu-PDI obtained according to the above step (1) and flat cylindrical Al2O3 foam ceramic with a specification of 0.25 m × 0.25 m (the addition amount is 1 g / dm 3) It was added to 3L DMF, and ultrasonic vibration and stirring were carried out sufficiently to fully load Cu-PDI on the porous foam ceramics. It was named Cu-PDI@AlC.

[0047] (3) Evaluation of the elimination performance of nitro compounds in water:

[0048] The photo-driven thermal catalytic reduction hydrogenation reaction experiment was carried out using a 300W Xe lamp as the light source. Under the atmosphere of air, 3-4 pieces of Cu-PDI@AlC obtained in the above step (2) strung together with a rope were added to a 3L glass reactor. After adding trinitrotoluene and 85% hydrazine hydrate in a molar ratio of 1:10, it was sealed. Under the condition of full-light illumination of the xenon lamp without a filter, after stirring at room temperature for 1.5 h, the mixture was centrifuged and the supernatant was taken, and the product content was purified by gas chromatography rapid chromatography and the data was recorded.

[0049] (4) Recovery of Cu-PDI@AlC:

[0050] Just lift the rope to recover the catalytic material and use it for the next reaction.

[0051] Example 2

[0052] The preparation method of a foam ceramic-metal organic framework composite catalytic material and its method for photo-thermal catalytic elimination of nitro compounds in this example is only different from the preparation method of Example 1 in that: in the hydrothermal reaction process described in step (1) of this example, copper nitrate trihydrate as the reaction substrate was equally replaced with any one of ferric chloride, nickel chloride, zinc nitrate, manganese chloride or cerium chloride, and was labeled as samples 2-6.

[0053] Example 3

[0054] The preparation method of a foam ceramic-metal organic framework composite catalytic material and its method for photo-thermal catalytic elimination of nitro compounds in this example is only different from the preparation method of Example 1 in that: in step (1) of this example, phenanthroline tetracarboxylic acid phenylimide was equally replaced with any one of 5-aminoisophthalic acid, 1,4,5,8-naphthalenetetracarboxylic dianhydride, and tetrakis(4-carboxyphenyl)porphine, and was labeled as samples 7-9. The structural formulas of each organic ligand are as Figure 2 .

[0055] Figure 3 are the FTIR spectra and XRD patterns of the catalyst Cu-MOFs in Example 1 and Example 3. The crystal structures of the obtained samples were studied by X-ray diffraction spectroscopy (XRD), and the results are as Figure 3As shown in a. The four Cu-MOFs show obvious diffraction peaks in the low-angle region, indicating their high crystallinity. The peaks of Cu-NTCDA are located at 11.6° and 19.0°, corresponding to the (400) and (440) planes. The peaks of Cu-TCPP are located at 9.02° and 17.92°, corresponding to the (110) and (002) planes. The Cu-AIPA sample has obvious characteristic peaks at 8.9°, 9.5° and 12.3°. The Cu-PDI sample has obvious characteristic peaks at 10.24°, 10.82°, 14.07° and 15.33°.

[0056] The surface functional groups of the catalyst were analyzed by Fourier transform infrared spectroscopy (FTIR). Figure 3 b shows that Cu-PDI, Cu-NTCDA, Cu-AIPA and Cu-TCPP have similar characteristic peaks, indicating the successful synthesis of these MOFs, but the changes in peak intensity and position reflect the influence of different ligands on the structure of Cu-MOF. The peaks between 764 and 642 cm -1 in Cu-PDI, Cu-NTCDA, Cu-AIPA and Cu-TCPP correspond to the out-of-plane bending vibration of the C-H bond in the benzene ring. The strong peak at 1251 cm -1 in the FT-IR spectrum of Cu-PDI is attributed to the stretching vibration of the C-O bond. However, a new band appears in the range of 775 - 728 cm -1 , which is the change caused by the coordination of carboxyl group and metal ions. The characteristic peak at 1609 cm -1 in the FT-IR spectrum of Cu-TCPP is attributed to the stretching vibration of the C=O bond, and a new characteristic peak appears at 998 cm -1 , indicating that the hydrogen proton is replaced by the copper ion. The peak at 1575 cm -1 in the FT-IR spectrum of Cu-AIPA is due to the stretching vibration of the N-H bond of the free -NH2 group. The two sharp peaks at 1624 cm -1 in the FT-IR spectrum of Cu-NTCDA belong to the asymmetric and symmetric stretching modes of the COOH of the carboxyl group respectively. The two bands at 1570 cm -1 and 676 cm -1 belong to the vibration of the phenyl ring, while the two bands at 571 cm -1 correspond to the Cu-O bond.

[0057] Figure 4 are the SEM characterization diagrams of the catalysts Cu-MOFs in Example 1 and Example 3. Figure 4The morphological diagrams of Cu-PDI, Cu-NTCDA, Cu-AIPA, and Cu-TCPP are shown. Cu-PDI is a fibrous network structure; Cu-NTCDA is a flaky structure with a thickness of about 1 μm; Cu-AIPA presents a flower-like or spherical structure with many small protrusions on the surface; Cu-TCPP presents a layered or flaky structure.

[0058] Example 4

[0059] A method for preparing a foam ceramic-metal organic framework composite catalytic material and its photothermal catalytic elimination of nitro compounds in this example is only different from the preparation method of Example 1 in that: during the hydrothermal reaction process described in step (1) of this example, the hydrothermal temperature is changed to 120 °C, 140 °C, 160 °C, 180 °C, 200 °C, marked as samples 10-14.

[0060] Example 5

[0061] A method for preparing a foam ceramic-metal organic framework composite catalytic material and its photothermal catalytic elimination of nitro compounds in this example is only different from the preparation method of Example 1 in that: during the in-situ loading process described in step (2) of this example, the Al2O3 foam ceramic is equally replaced by any one of silicon carbide (SiC) and zirconia (ZrO2), marked as samples 15-16.

[0062] Example 6

[0063] A method for preparing a foam ceramic-metal organic framework composite catalytic material and its photothermal catalytic elimination of nitro compounds in this example is only different from the preparation method of Example 1 in that: the cylindrical foam ceramic described in step (2) of this example can be equally replaced by shapes such as spherical and cube, marked as samples 17-18. The shape of the foam ceramic is as Figure 1 shown.

[0064] Example 7

[0065] A method for preparing a foam ceramic-metal organic framework composite catalytic material and its photothermal catalytic elimination of nitro compounds in this example is only different from the preparation method of Example 1 in that: nitrobenzene described in step (3) of this example can be replaced by other reaction substrates such as trinitrophenol, dinitrobenzene, nitrochlorobenzene, etc. Marked as samples 19-21.

[0066] Example 8

[0067] A method for preparing a foam ceramic-metal organic framework composite catalytic material and its use in photocatalytic elimination of nitro compounds in this example is only different from the preparation method in Example 1 in that: in step (3) of this example, the reducing agent can be changed to sodium borohydride or borane ammonia, marked as Samples 22-23.

[0068] Example 9

[0069] A method for preparing a foam ceramic-metal organic framework composite catalytic material and its use in photocatalytic elimination of nitro compounds in this example is only different from the preparation method in Example 1 in that: during the hydrothermal reaction process described in step (1) of this example, the reaction substrate copper nitrate trihydrate is replaced by any two of ferric chloride, nickel chloride, zinc nitrate, manganese chloride or cerium chloride, and the molar ratio of metal salt 1, metal salt 2 and organic ligand is 1:1:2 to synthesize bimetallic MOFs. Marked as Samples 24-38.

[0070] Table 1: Sample number table of bimetallic MOFs

[0071]

[0072] Example 10

[0073] A method for preparing a foam ceramic-metal organic framework composite catalytic material and its use in photocatalytic elimination of nitro compounds in this example is only different from the preparation method in Example 1 in that: during the hydrothermal reaction process described in step (1) of this example, the reaction substrate copper nitrate trihydrate is replaced by a mixed metal salt with an equal amount of copper nitrate trihydrate and nickel chloride in a molar ratio of 1:1. The phenylpropionyl imine phenanthroline tetracarboxylic acid is equivalently replaced by any one of 5-aminoisophthalic acid, 1,4,5,8-naphthalenetetracarboxylic dianhydride, and tetrakis(4-carboxyphenyl)porphyrin to synthesize CuNi-MOFs. Marked as Samples 39-41.

[0074] Performance evaluation

[0075] Table 2: Elimination conversion rates of trinitrotoluene in water for different samples

[0076]

[0077]

[0078]

[0079] Figure 5 Schematic diagram of foam ceramic supported MOFs and photocatalytic elimination of nitro compounds in water;

[0080] Under the condition of full-spectrum light irradiation, the performance of photocatalytic thermal catalysis for the elimination of nitro compound pollutants in water was evaluated. The data in Table 2 show that the elimination conversion rates of trinitrotoluene in water by Samples 2 to 6 within 1.5 hours were slightly lower than that of Sample 1, indicating that the catalyst with copper (Cu) as the metal center had the best performance. In addition, there were also differences in the catalytic performances of copper-based metal-organic frameworks (MOFs, Samples 7 to 9) synthesized with different organic ligands. Among them, the MOF with phenylpropionyl imine phenanthroline tetracarboxylic acid as the organic ligand had the highest conversion rate, reaching 88%, while the performance of the MOF with tetrakis(4-carboxyphenyl) porphyrin as the organic ligand was relatively low. These four copper-based MOFs could all effectively eliminate nitro compounds in water and showed good degradation ability for different types of nitro compound pollutants (Samples 19 to 21). The bimetallic MOFs (Samples 24 to 38) had relatively high elimination conversion rates of trinitrotoluene in water (>60%), and after changing different organic ligands (Samples 39 to 41), they could still effectively eliminate the target compounds.

[0081] When loading MOF powders onto the foam ceramic material, the shape and type of the foam ceramic had significant effects on the loading amount of the powders and the contact area between the catalytic material and the reaction system, thus affecting the yield of the final reduction product. The results in Table 2 show that when using cylindrical alumina foam ceramic with a pore size of 50 nm to load MOFs, the elimination conversion rate of trinitrotoluene in water could reach 88%. This indicates that the foam ceramic-metal organic framework composite catalytic material has good application prospects in the photocatalytic thermal elimination of nitro compounds.

[0082] Summary: MOFs have a high specific surface area and adjustable pore structures, which can provide a large number of active sites, thus enhancing the efficiency of catalytic reactions. As a carrier, the porous foam ceramic can evenly disperse MOF powders, increase the contact area between the catalyst and the reactants, and improve the catalytic effect. Then, loading MOF powders on the porous foam ceramic can improve their stability during the reaction process, reduce the aggregation and loss of MOF powders, and extend the service life of the catalyst. The porous nature of the foam ceramic material is more conducive to the fixation of the catalyst, enabling multiple cycles of use. By adjusting the pore size and porosity of the porous foam ceramic, as well as the type and loading amount of MOFs, the performance of the catalyst can be customized to meet the requirements of different catalytic reactions. In addition, using alumina foam ceramic to load Cu-based MOFs for photocatalytic thermal reduction reaction, this innovation not only strengthens the stability of MOFs, but also effectively prevents the problems of high cost, high energy consumption, and high temperature danger in traditional thermal catalysis, further improving the efficiency of eliminating nitro compounds.

Claims

1. A method for preparing a foam ceramic-metal organic framework composite catalytic material, characterized in that: The steps include: (1) Preparation of single metal organic frameworks MOFs: The organic ligand and soluble metal salt are dissolved in N,N'-dimethylformamide solution in proportion, and acetonitrile, deionized water and concentrated hydrochloric acid are added in proportion and mixed, and stirred evenly at room temperature; after the hydrothermal reaction, the product is separated into green transparent block crystals by centrifugation, washed with ethanol several times, and vacuum dried to obtain a single metal MOFs material, named M-MOFs; (2) Preparation of bimetallic MOFs: The organic ligand, soluble metal salt 1 and soluble metal salt 2 are dissolved in N,N'-dimethylformamide solution in proportion, and acetonitrile, deionized water and concentrated hydrochloric acid are added and mixed, and stirred evenly at room temperature; after the hydrothermal reaction, the product is separated into green transparent block crystals by centrifugation, washed with ethanol several times, and vacuum dried to obtain a bimetallic MOFs material, named MM-MOFs; (3) Preparation of solid support devices: The M-MOFs obtained in step (1) or the MM-MOFs obtained in step (2) and Al2O3, SiC or ZrO2 foam ceramics are added into DMF respectively, and ultrasonic vibration and stirring are performed sufficiently to make the MOFs material fully loaded on the porous foam ceramics, so as to obtain foam ceramic-metal organic framework composite catalytic materials, which are named M-MOFs@AlC, M-MOFs@SiC, M-MOFs@Zr or MM-MOFs@AlC, MM-MOFs@SiC, MM-MOFs.

2. The method for preparing the foam ceramic-metal organic framework composite catalytic material according to claim 1, characterized in that: In step (1) or (2), the organic ligand comprises one of phenylpropionimide phenanthroline tetracarboxylic acid (PDI), 5-aminoisophthalic acid (AIPA), 1,4,5,8-naphthalenetetracarboxylic anhydride (NTCDA) or tetrakis(4-carboxyphenyl)porphine (TCPP).

3. The method for preparing the foam ceramic-metal organic framework composite catalytic material according to claim 1, characterized in that: In step (1), the soluble metal salt includes one of CuCl2·3H2O, FeCl3·6H2O, NiCl2·6H2O, CeCl3, Mn(NO2)2 and Zn(NO2)2.

4. The method for preparing the foam ceramic-metal organic framework composite catalytic material according to claim 1, characterized in that: In step (1), the molar ratio of the organic ligand to the soluble metal salt is 1:1; and the molar ratio of the added acetonitrile, deionized water, concentrated hydrochloric acid to the organic ligand is 20:56:0.5:

1.

5. The method for preparing the foam ceramic-metal organic framework composite catalytic material according to claim 1, characterized in that: In step (2), the soluble metal salt 1 and the soluble metal salt 2 include any two of CuCl2·3H2O, FeCl3·6H2O, NiCl2·6H2O, CeCl3, Mn(NO2)2 and Zn(NO2)2.

6. The method for preparing the foam ceramic-metal organic framework composite catalytic material according to claim 1, characterized in that: In step (2), the molar ratio of the organic ligand, the soluble metal salt 1 and the soluble metal salt 2 is 2:1:1; the molar ratio of the added acetonitrile, deionized water, concentrated hydrochloric acid and the organic ligand is 20:56:0.5:

1.

7. The method for preparing the foam ceramic-metal organic framework composite catalytic material according to claim 1, characterized in that: In step (3), the Al2O3, SiC or ZrO2 foam ceramic has a shape and size of a flat cylinder, a sphere or a cube, and a pore size of 2 to 50 nm; The dosage of M-MOFs or MM-MOFs is: per 1dm 3 1 g of M-MOFs or MM-MOFs was added to the foam ceramic.

8. The method for preparing the foam ceramic-metal organic framework composite catalytic material according to claim 1, characterized in that: In step (1) or (2), the temperature of the hydrothermal reaction is 80-200° C., and the time of the hydrothermal reaction is 48 hours.

9. Use of the foam ceramic-metal organic framework composite catalytic material obtained by the preparation method according to any one of claims 1 to 8 for photothermal catalytic elimination of nitro compounds in water.

10. The use according to claim 9, characterized in that The steps are: In an air atmosphere, a ceramic foam-metal organic framework composite catalytic material is added to a reaction vessel containing a mixed solution of a nitro compound and a reducing agent, and the nitro compound is degraded and converted into an aromatic amino compound under the condition of sunlight or a 300W Xe lamp simulating sunlight. The nitro compound is trinitrotoluene, dinitrobenzene, nitrochlorobenzene, nitrophenol or halogen nitrobenzene; The reducing agent is one of hydrazine hydrate, sodium borohydride and borane ammonia; When the reducing agent is hydrazine hydrate, the molar ratio of the nitro compound to hydrazine hydrate is 1:10; When the reducing agent is sodium borohydride, the molar ratio of the nitro compound to sodium borohydride is 1:6; When the reducing agent is borane, the molar ratio of the nitro compound to borane is 1:4.

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