A catalytic reaction filter membrane and its preparation method and application

Abstract

The present invention belongs to the field of filter membrane technology. The present invention provides a catalytic reaction filter membrane and its preparation method and application. The preparation method of the catalytic reaction filter membrane comprises the following steps: spraying a mixture of a palladium metal precursor solution and a tin metal precursor solution on the surface of the etched titanium foam to obtain a titanium foam containing palladium and tin; soaking the titanium foam containing palladium and tin in a reducing agent to obtain a catalytic reaction filter membrane loaded with a nano-palladium-tin alloy. The catalytic reaction filter membrane prepared by the present invention has a high loading intensity of active metal components and stable denitrification performance. When used in the denitrification of nitric nitrogen wastewater, formic acid is used as an electron donor, which avoids the risk of hydrogen leakage in the traditional hydrogen reduction process, greatly reduces the manufacturing cost and operation requirements of the equipment, and has good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of filter membranes, and in particular to a catalytic reaction filter membrane and a preparation method and application thereof. Background Art

[0002] Due to the extensive use of nitrogen fertilizers and the improper disposal of domestic sewage and nitrogen-containing industrial wastewater, nitrate-nitrogen has become a major pollutant in surface water and groundwater. Currently, the main treatment methods for nitrate-nitrogen in wastewater include physical methods (ion exchange, reverse osmosis, and electrodialysis), biological denitrification, and chemical catalysis (catalytic reduction and electrochemical reduction). In contrast, physical methods can only achieve simple enrichment of nitrate-nitrogen, and the denitrification efficiency of biological denitrification is easily affected by factors such as system temperature and pH. Chemical catalysis, however, has attracted widespread attention due to its high treatment efficiency, simple and easy-to-operate equipment, and low operating costs.

[0003] The catalytic reduction of nitrate nitrogen is a process that uses hydrogen as an electron donor to reduce nitrate nitrogen to nitrogen under the action of a catalyst, without the need for power supply and electrode equipment. Compared with the electrochemical reduction method, this catalytic method is more suitable for treating wastewater with low electrolyte concentration or containing calcium and magnesium ions. However, in traditional nitrate nitrogen catalytic reduction treatment, the active metal is often loaded onto a powder carrier by an impregnation method to prepare the catalyst, which not only easily causes the active metal to fall off and reduces the catalytic activity of the catalyst, but also is not conducive to the recycling of the catalyst. In addition, hydrogen, as a flammable and explosive gas, has a high operational risk when used, and its low solubility in water will significantly reduce its utilization rate and increase the cost of wastewater treatment.

[0004] Formic acid, an inexpensive industrial product that is easy to transport and store, not only has high reducing properties but also decomposes into CO2, preventing secondary pollution. Therefore, the development of a catalytic reaction membrane using formic acid as an electron donor, with a high loading of active metal components and stable denitrification performance, and its preparation method holds great promise. Summary of the Invention

[0005] The purpose of the present invention is to provide a catalytic reaction filter membrane and a preparation method and application thereof in view of the deficiencies in the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a catalytic reaction filter membrane, comprising the following steps:

[0008] 1) spraying a mixture of a palladium metal precursor solution and a tin metal precursor solution on the surface of the etched titanium foam to obtain a titanium foam containing palladium and tin;

[0009] 2) The palladium and tin-containing titanium foam is immersed in a reducing agent to obtain a catalytic reaction filter membrane.

[0010] Preferably, the etching reagent in step 1) is oxalic acid solution, the mass concentration of the oxalic acid solution is 1-10%, the etching temperature is 40-120° C., and the etching time is 1-600 min.

[0011] Preferably, the titanium foam in step 1) has a titanium content of 90-95%, a pore size of 10-80 μm, a thickness of 0.1-2 mm, and a length and width of 30-50 mm independently.

[0012] Preferably, the concentrations of the palladium metal precursor solution and the tin metal precursor solution are independently 100-200 mg / L, the volume ratio of the palladium metal precursor solution and the tin metal precursor solution is 1:0.1-4, and the solvents of the palladium metal precursor solution and the tin metal precursor solution are independently water, anhydrous ethanol, acetone, acetonitrile, ethylene glycol or isopropanol.

[0013] Preferably, the palladium metal precursor is palladium dichloride, chloropalladic acid, sodium chloropalladate, palladium acetylacetonate or palladium nitrate; and the tin metal precursor is tin tetrachloride or tin dichloride.

[0014] Preferably, the spraying temperature in step 1) is 200-700° C., the spraying flow rate is 4-6 mL / min, and the spraying time is 14-16 min;

[0015] The palladium loading amount on the surface of the palladium- and tin-containing foamed titanium is 0.001-15 wt%, and the tin loading amount is 0.001-45 wt%.

[0016] Preferably, the reducing agent in step 2) is sodium borohydride solution, potassium borohydride solution, dimethylaminoborane solution, lithium aluminum hydride solution or hydrazine hydrate solution, and the concentration of the reducing agent is 0.001 to 1 mol / L.

[0017] Preferably, the soaking treatment temperature in step 2) is 20-30° C., and the soaking treatment time is 0.1-60 min.

[0018] The present invention also provides a catalytic reaction filter membrane prepared by the preparation method.

[0019] The present invention also provides an application of the catalytic reaction filter membrane in denitrification of nitrate nitrogen wastewater, which comprises passing a mixed solution of nitrate nitrogen wastewater and formic acid through the catalytic reaction filter membrane;

[0020] The purity of the formic acid is 60-100%; in the mixed solution of nitric nitrogen wastewater and formic acid, the molar ratio of formic acid to nitrate ion is 0.1-50:1.

[0021] The beneficial effects of the present invention include the following:

[0022] 1) The nano-palladium-tin alloy loaded on the catalytic reaction filter membrane of the present invention has excellent formic acid decomposition performance, which helps to improve the catalytic reduction rate of nitric nitrogen and nitrogen selectivity.

[0023] 2) The present invention uses high-temperature spraying + chemical reduction to load the nano-palladium-tin alloy on the foam titanium substrate. The high-porosity foam titanium provides a high specific surface area, which is conducive to the fixation of the active metal components and improves the stability of the active metal components.

[0024] 3) The present invention uses titanium foam loaded with nano-palladium-tin alloy for the catalytic reduction of nitric nitrogen wastewater, achieving efficient utilization and convenient recovery of the catalyst. Compared with the method of directly adding powdered catalyst, the operation process is simplified and the operation complexity is reduced.

[0025] 4) The catalytic reaction filter membrane prepared by the present invention has a high active metal component loading intensity and stable denitrification performance. When used in the denitrification of nitric nitrogen wastewater, formic acid is used as an electron donor, which avoids the risk of hydrogen leakage in the traditional hydrogen reduction process, greatly reduces the manufacturing cost and operating requirements of the equipment, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the device for the catalytic reaction membrane in the denitrification process of nitrate nitrogen wastewater according to the embodiment and the comparative example, wherein 1 is the catalytic reaction membrane, 2 is the flow cell, 3 is the water pump, and 4 is the liquid storage tank;

[0027] Figure 2 This is a scanning electron microscope image of the catalytic reaction filter membrane of Example 1;

[0028] Figure 3 This is a transmission electron micrograph of the nano-palladium-tin alloy particles loaded on the catalytic reaction filter membrane of Example 1;

[0029] Figure 4 This is a technical principle diagram of the catalytic reaction membrane of Examples 1 and 2 in the denitrification process of nitrate nitrogen wastewater. DETAILED DESCRIPTION

[0030] The present invention provides a method for preparing a catalytic reaction filter membrane, comprising the following steps:

[0031] 1) spraying a mixture of a palladium metal precursor solution and a tin metal precursor solution on the surface of the etched titanium foam to obtain a titanium foam containing palladium and tin;

[0032] 2) The palladium and tin-containing titanium foam is immersed in a reducing agent to obtain a catalytic reaction filter membrane.

[0033] In the present invention, the etching reagent in step 1) is preferably an oxalic acid solution; the mass concentration of the oxalic acid solution is preferably 1-10%, more preferably 3-8%, and more preferably 4-6%; the etching temperature is preferably 40-120°C, more preferably 60-100°C, and more preferably 80°C; the etching time is preferably 1-600 min, more preferably 120-400 min, and more preferably 200-300 min.

[0034] In the present invention, after etching is completed, the foamed titanium is preferably washed; the washing agent is preferably deionized water, and the number of washing times is preferably 4 to 6 times, more preferably 5 times.

[0035] In the present invention, the titanium content of the titanium foam in step 1) is preferably 90-95%, more preferably 92-94%, more preferably 93%, the pore size is preferably 10-80 μm, more preferably 30-60 μm, more preferably 40-50 μm, the thickness is preferably 0.1-2 mm, more preferably 1-1.5 mm, more preferably 1.2 mm, and the length and width are independently preferably 30-50 mm, more preferably 35-45 mm, more preferably 40 mm.

[0036] In the present invention, the concentration of the palladium metal precursor solution and the tin metal precursor solution is independently preferably 100-200 mg / L, more preferably 140-160 mg / L, and more preferably 150 mg / L; the volume ratio of the palladium metal precursor solution and the tin metal precursor solution is preferably 1:0.1-4, more preferably 1:1-3, and more preferably 1:2; the solvent of the palladium metal precursor solution and the tin metal precursor solution is independently preferably water, anhydrous ethanol, acetone, acetonitrile, ethylene glycol or isopropanol.

[0037] In the present invention, the palladium metal precursor is preferably palladium dichloride, chloropalladic acid, sodium chloropalladate, palladium acetylacetonate or palladium nitrate; and the tin metal precursor is preferably tin tetrachloride or tin dichloride.

[0038] In the present invention, the spraying temperature in step 1) is preferably 200-700° C., more preferably 300-600° C., and more preferably 450-500° C.; the spraying flow rate is preferably 4-6 mL / min, more preferably 4.5-5.5 mL / min, and more preferably 5 mL / min; the spraying time is preferably 14-16 min, more preferably 14.5-15.5 min, and more preferably 15 min;

[0039] The palladium loading on the surface of the titanium foam containing palladium and tin is preferably 0.001 to 15 wt%, more preferably 0.1 to 10 wt%, and more preferably 4 to 8 wt%; the tin loading is preferably 0.001 to 45 wt%, more preferably 10 to 35 wt%, and more preferably 20 to 30 wt%.

[0040] In the present invention, after the spraying is completed, the titanium foam is preferably cooled, and the cooling temperature is preferably room temperature.

[0041] In the present invention, the reducing agent in step 2) is preferably sodium borohydride solution, potassium borohydride solution, dimethylaminoborane solution, lithium aluminum hydride solution or hydrazine hydrate solution, and the concentration of the reducing agent is preferably 0.001 to 1 mol / L, more preferably 0.1 to 0.8 mol / L, and more preferably 0.3 to 0.6 mol / L.

[0042] In the present invention, the soaking treatment temperature in step 2) is preferably 20-30° C., more preferably 25° C.; the soaking treatment time is preferably 0.1-60 min, more preferably 10-50 min, and more preferably 30-40 min.

[0043] In the present invention, after the soaking treatment is completed, the foamed titanium is preferably washed; the washing agent is preferably deionized water, and the number of washing times is preferably 4 to 6 times, more preferably 5 times.

[0044] The present invention also provides a catalytic reaction filter membrane prepared by the preparation method.

[0045] The present invention also provides an application of the catalytic reaction filter membrane in denitrification of nitrate nitrogen wastewater, which comprises passing a mixed solution of nitrate nitrogen wastewater and formic acid through the catalytic reaction filter membrane;

[0046] The purity of the formic acid is 60-100%; in the mixed solution of nitric nitrogen wastewater and formic acid, the molar ratio of formic acid to nitrate ion is 0.1-50:1.

[0047] In the present invention, when the catalytic reaction filter membrane is used in the denitrification of nitrate nitrogen wastewater, the purity of the formic acid is 60-100%, preferably 70-90%, more preferably 75-85%, and more preferably 80%; in the mixed solution of nitrate nitrogen wastewater and formic acid, the molar ratio of formic acid to nitrate ion is 0.1-50:1, preferably 10-40:1, more preferably 20-30:1, and more preferably 25:1.

[0048] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0049] When the catalytic reaction filter membrane prepared in the embodiment and comparative example is used in the denitrification of nitric nitrogen wastewater, the device schematic diagram is as follows: Figure 1 As shown, 1 is a catalytic reaction filter membrane, 2 is a flow cell, 3 is a water pump, and 4 is a liquid storage tank;

[0050] The water quality of the nitric nitrogen wastewater from the parts pickling workshop of COMAC Shanghai Aircraft Manufacturing Co., Ltd. described in the examples is as follows: the concentration of nitric nitrogen is 138.1 mg / L, the concentration of ammonia nitrogen is 0.5 mg / L, and no nitrite nitrogen is contained.

[0051] Example 1

[0052] A titanium foam with a titanium content of 95%, a pore size of 50 μm, a thickness of 1 mm, and a length and width of 40 mm was etched in an oxalic acid solution with a temperature of 80°C and a mass concentration of 10% for 120 minutes. The titanium foam was then taken out and washed with deionized water 5 times to obtain the etched titanium foam.

[0053] A mixture of palladium dichloride solution and tin tetrachloride solution was sprayed on the surface of the etched titanium foam, wherein the volume ratio of the palladium dichloride solution to the tin tetrachloride solution in the mixture was 1:1, the concentrations of the palladium dichloride solution and the tin tetrachloride solution were both 100 mg / L, the solvent of the palladium dichloride solution was deionized water, and the solvent of the tin tetrachloride solution was anhydrous ethanol. The spraying temperature was 450°C, the spraying flow rate was 5 mL / min, the spraying time was 15 min, and then the mixture was naturally cooled to room temperature to obtain palladium- and tin-containing titanium foam (the loading amounts of palladium and tin on the surface of the palladium- and tin-containing titanium foam were both 0.1 wt%).

[0054] The palladium and tin-containing titanium foam was immersed in a 0.3 mol / L sodium borohydride solution at 25° C. for 30 minutes, and then the titanium foam was taken out and washed five times with deionized water to obtain a catalytic reaction filter membrane.

[0055] The scanning electron microscope image of the catalytic reaction filter membrane prepared in this embodiment is as follows: Figure 2 As shown by Figure 2 It can be seen that the nano-palladium-tin alloy particles are evenly dispersed on the surface of the titanium foam; the transmission electron microscope image of the nano-palladium-tin alloy particles loaded on the catalytic reaction filter membrane is as follows Figure 3 As shown by Figure 3 It can be seen that the particle size distribution of nano palladium-tin alloy particles is 4 to 15 nm.

[0056] The catalytic reaction filter membrane prepared in this example was applied to the denitrification of nitrate nitrogen wastewater. The specific operation was as follows: 98% pure formic acid was added to 200 mL of simulated nitrate nitrogen wastewater with a nitrate concentration of 102.2 mg / L to obtain a mixture of nitrate nitrogen wastewater and formic acid (the molar ratio of formic acid to nitrate in the mixture was 4:1); the catalytic reaction filter membrane was placed in a flow cell, the mixture of nitrate nitrogen wastewater and formic acid was added to a liquid storage tank, and the mixture of nitrate nitrogen wastewater and formic acid was pumped from the liquid storage tank into the flow cell using a water pump at a water flow rate of 20 mL / min. The mixture then flowed through the catalytic reaction filter membrane and returned to the liquid storage tank. After the device was operated for 6 hours, its relevant indicators were tested: nitrogen selectivity = initial nitrate nitrogen concentration / initial total nitrogen concentration × 100%, total nitrogen concentration = nitrate nitrogen concentration + nitrite nitrogen concentration + ammonia nitrogen concentration. The test results of relevant indicators are shown in Table 1.

[0057] Table 1 Test results of relevant indicators of catalytic reaction membrane in denitrification of nitrate nitrogen wastewater in Example 1

[0058]

[0059] It can be seen from Table 1 that the catalytic reaction filter membrane prepared in this example has excellent nitric nitrogen reduction performance, with a nitric nitrogen removal rate of 98.5% and a nitrogen selectivity of 100%.

[0060] Example 2

[0061] A titanium foam with a titanium content of 95%, a pore size of 60 μm, a thickness of 2 mm, and a length and width of 50 mm was etched in an oxalic acid solution with a temperature of 100°C and a mass concentration of 10% for 150 minutes. The titanium foam was then taken out and washed with deionized water 5 times to obtain the etched titanium foam.

[0062] A mixture of palladium dichloride solution and tin tetrachloride solution was sprayed on the surface of the etched titanium foam, wherein the volume ratio of the palladium dichloride solution to the tin tetrachloride solution in the mixture was 1:1, the concentrations of the palladium dichloride solution and the tin tetrachloride solution were both 200 mg / L, the solvent of the palladium dichloride solution was deionized water, and the solvent of the tin tetrachloride solution was anhydrous ethanol. The spraying temperature was 450°C, the spraying flow rate was 5 mL / min, the spraying time was 15 min, and then the mixture was naturally cooled to room temperature to obtain palladium- and tin-containing titanium foam (the loading amounts of palladium and tin on the surface of the palladium- and tin-containing titanium foam were both 0.2 wt%).

[0063] The palladium and tin-containing titanium foam was immersed in a 0.3 mol / L sodium borohydride solution at a temperature of 30° C. for 40 minutes, and then the titanium foam was taken out and washed five times with deionized water to obtain a catalytic reaction filter membrane.

[0064] The catalytic reaction filter membrane prepared in this example was applied to the denitrification of nitric nitrogen wastewater. The nitric nitrogen wastewater used in the denitrification process was nitric nitrogen wastewater from the parts pickling workshop of Shanghai Aircraft Manufacturing Co., Ltd. of Commercial Aircraft Corporation of China. The water flow rate was 25 mL / min, the device operation time was 8 h, and other parameters were the same as those in Example 1. After the reaction was completed, the relevant indicators were tested. The test results of the relevant indicators are shown in Table 2.

[0065] Table 2 Test results of relevant indicators of catalytic reaction membrane in denitrification of nitrate nitrogen wastewater in Example 2

[0066]

[0067] It can be seen from Table 2 that the catalytic reaction filter membrane prepared in this embodiment still has excellent denitrification efficiency for actual nitric nitrogen wastewater, with a nitric nitrogen removal rate of 99.1% and a nitrogen selectivity of 99.6%.

[0068] The technical principle diagram of the catalytic reaction filter membrane prepared in Examples 1 and 2 in the process of denitrification of nitrate nitrogen wastewater is as follows Figure 4 As shown by Figure 4 It can be seen that when the wastewater flows through the catalytic reaction filter membrane, formic acid is catalytically decomposed on the nano-palladium-tin alloy, releasing electrons; at the same time, nitric nitrogen obtains electrons on the nano-palladium-tin alloy and undergoes a reduction reaction, converting into nitrogen.

[0069] Example 3

[0070] A titanium foam with a titanium content of 90%, a pore size of 40 μm, a thickness of 1.2 mm, and a length and width of 30 mm was etched in an oxalic acid solution with a temperature of 120°C and a mass concentration of 8% for 250 minutes. The titanium foam was then taken out and washed with deionized water 5 times to obtain the etched titanium foam.

[0071] A mixture of chloropalladium solution and tin dichloride solution was sprayed on the surface of the etched titanium foam, wherein the volume ratio of the chloropalladium solution and the tin dichloride solution in the mixture was 1:1, the concentrations of the chloropalladium solution and the tin dichloride solution were both 150 mg / L, the solvent of the chloropalladium solution was acetonitrile, and the solvent of the tin dichloride solution was acetone. The spraying temperature was 500°C, the spraying flow rate was 4 mL / min, the spraying time was 16 min, and then the foam was naturally cooled to room temperature to obtain palladium and tin-containing titanium foam (the loading amounts of palladium and tin on the surface of the palladium and tin-containing titanium foam were both 0.5 wt%).

[0072] The palladium and tin-containing titanium foam was immersed in a 0.5 mol / L dimethylaminoborane solution at a temperature of 20° C. for 35 minutes, and then the titanium foam was taken out and washed five times with deionized water to obtain a catalytic reaction filter membrane.

[0073] Example 4

[0074] A titanium foam with a titanium content of 94%, a pore size of 60 μm, a thickness of 0.8 mm, and a length and width of 45 mm was etched in an oxalic acid solution with a temperature of 90°C and a mass concentration of 7% for 400 minutes. The titanium foam was then taken out and washed with deionized water 5 times to obtain the etched titanium foam.

[0075] A mixture of sodium chloropalladate solution and tin dichloride solution was sprayed on the surface of the etched titanium foam, wherein the volume ratio of the sodium chloropalladate solution to the tin dichloride solution in the mixture was 1:1, the concentrations of the sodium chloropalladate solution and the tin dichloride solution were both 120 mg / L, the solvent of the sodium chloropalladate solution was ethylene glycol, and the solvent of the tin dichloride solution was isopropanol. The spraying temperature was 550°C, the spraying flow rate was 6 mL / min, the spraying time was 14 min, and then the mixture was naturally cooled to room temperature to obtain titanium foam containing palladium and tin (the loading amounts of palladium and tin on the surface of the titanium foam containing palladium and tin were both 1 wt %).

[0076] The palladium and tin-containing titanium foam was immersed in a lithium aluminum hydride solution with a concentration of 1 mol / L at a temperature of 25° C. for 40 minutes, and then the titanium foam was taken out and washed with deionized water for 5 times to obtain a catalytic reaction filter membrane.

[0077] Comparative Example 1

[0078] The mixed solution of nitrate nitrogen wastewater and formic acid used in the catalytic reaction membrane denitrification of nitrate nitrogen wastewater in Example 1 was modified into an equal amount of single nitrate nitrogen wastewater. Other conditions were the same as in Example 1. After the reaction was completed, the relevant indicators were tested. The test results of the relevant indicators are shown in Table 3.

[0079] Table 3 Test results of relevant indicators of the catalytic reaction filter membrane of comparative example 1 in the denitrification of nitrate nitrogen wastewater (excluding formic acid)

[0080]

[0081] It can be seen from Table 3 that the catalytic reduction of nitric nitrogen cannot be carried out in this comparative example due to the lack of formic acid as an electron donor.

[0082] Comparative Example 2

[0083] The process of spraying the tin tetrachloride solution when preparing the catalytic reaction filter membrane in Example 1 was omitted, and other conditions remained unchanged to obtain a catalytic reaction filter membrane. The catalytic reaction filter membrane was used in the denitrification reaction of nitrate nitrogen wastewater according to the same operation as in Example 1. After the reaction was completed, the relevant indicators were tested. The test results of the relevant indicators are shown in Tables 4 and 5.

[0084] Table 4 Test results of relevant indicators of catalytic reaction filter membrane in comparative example 2 in denitrification of nitrate nitrogen wastewater

[0085]

[0086] Table 5 Detection results of formic acid concentration in nitrate nitrogen wastewater denitrification by catalytic reaction filter membrane of comparative example 2

[0087]

[0088] It can be seen from Tables 4 and 5 that when preparing the catalytic reaction filter membrane, without the participation of the tin metal component, the palladium metal component can only decompose formic acid and cannot achieve the catalytic reduction of nitric acid. This shows that the palladium site is involved in the decomposition of formic acid, while the reduction of nitric acid occurs at the tin site. The lack of tin sites will result in the nitric acid being unable to utilize the electrons generated by the decomposition of formic acid.

[0089] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. Application of a catalytic reaction filter membrane in denitrification of nitrate nitrogen wastewater, characterized in that: The following steps are included: 1) spraying a mixture of a palladium metal precursor solution and a tin metal precursor solution on the surface of the etched titanium foam to obtain a titanium foam containing palladium and tin; 2) soaking the palladium and tin-containing titanium foam in a reducing agent to obtain a catalytic reaction filter membrane; Step 2) The reducing agent is a sodium borohydride solution or a potassium borohydride solution, and the concentration of the reducing agent is 0.001-1 mol / L; A nano-palladium-tin alloy loaded on a catalytic reaction filter membrane is prepared; The mixture of nitric nitrogen wastewater and formic acid is passed through the catalytic reaction filter membrane; The purity of the formic acid is 60-100%; in the mixed solution of nitric nitrogen wastewater and formic acid, the molar ratio of formic acid to nitrate ion is 0.1-50:

1.

2. The use of the catalytic reaction filter membrane according to claim 1 in denitrification of nitrate nitrogen wastewater, characterized in that: In step 1), the etching reagent is oxalic acid solution, the mass concentration of the oxalic acid solution is 1-10%, the etching temperature is 40-120° C., and the etching time is 1-600 min.

3. The use of the catalytic reaction filter membrane according to claim 2 in denitrification of nitrate nitrogen wastewater, characterized in that: Step 1) The titanium foam has a titanium content of 90-95%, a pore size of 10-80 μm, a thickness of 0.1-2 mm, and a length and width of 30-50 mm independently.

4. The use of the catalytic reaction filter membrane according to claim 1 in denitrification of nitrate nitrogen wastewater, characterized in that: The concentrations of the palladium metal precursor solution and the tin metal precursor solution are independently 100-200 mg / L, the volume ratio of the palladium metal precursor solution to the tin metal precursor solution is 1:0.1-4, and the solvents of the palladium metal precursor solution and the tin metal precursor solution are independently water, anhydrous ethanol, acetone, acetonitrile, ethylene glycol or isopropanol.

5. Application of the catalytic reaction filter membrane in denitrification of nitrate nitrogen wastewater according to claim 4, characterized in that: The palladium metal precursor is palladium dichloride, chloropalladic acid, sodium chloropalladate, palladium acetylacetonate or palladium nitrate; the tin metal precursor is tin tetrachloride or tin dichloride.

6. Use of the catalytic reaction filter membrane according to claim 5 in denitrification of nitrate nitrogen wastewater, characterized in that: Step 1) The spraying temperature is 200-700°C, the spraying flow rate is 4-6 mL / min, and the spraying time is 14-16 minutes; The palladium loading amount on the surface of the palladium- and tin-containing titanium foam is 0.001-15 wt %, and the tin loading amount is 0.001-45 wt %.

7. Use of the catalytic reaction filter membrane according to claim 1 in denitrification of nitrate nitrogen wastewater, characterized in that: Step 2) The soaking temperature is 20-30° C., and the soaking time is 0.1-60 min.

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