A method for preparing a multi-channel Ni / CM ceramic catalytic membrane

Abstract

This invention relates to the preparation of a multi-channel Ni / CM ceramic catalytic membrane, belonging to the field of membrane catalysis technology. The invention utilizes a hydrothermal method to grow Ni-BTC in situ on the surface and within the pores of a multi-channel ceramic membrane, followed by calcination in a reducing atmosphere to obtain the catalytic membrane. The preparation process is simple. The resulting catalytic membrane exhibits high catalytic activity and stability, while avoiding catalyst-product separation, facilitating catalyst recovery and reuse.

Description

Technical Field

[0001] This invention belongs to the field of catalytic membrane preparation technology, and relates to a method for preparing a multi-channel Ni / CM ceramic catalytic membrane. Background Technology

[0002] p-Nitrophenol is an aromatic nitro compound and a persistent, harmful pollutant widely found in various industrial and agricultural wastewaters. Even trace amounts of p-nitrophenol can cause significant harm to human health and the natural environment. Currently, the common strategy for treating p-nitrophenol is to convert it into other components, such as p-aminophenol, at room temperature. p-Aminophenol is an essential intermediate in the pharmaceutical industry, and its toxicity is less than 1 / 500th that of p-nitrophenol. In recent years, noble metals and their alloys (Pd, Au, and Ag), transition metal oxides, and hybrid materials have been applied to the catalytic reduction of p-nitrophenol. Although noble metal catalysts exhibit high catalytic activity, their cost and scarcity still limit their application. Furthermore, to improve activity, noble metals are often supported on fine-grained supports; these powdered catalysts are prone to deactivation during use, and the recovery and reuse process is complex and has low recovery rates, leading to increased production costs. Therefore, the development of highly efficient novel catalytic materials for the reduction of p-nitrophenol has attracted considerable attention.

[0003] Catalytic membranes are materials in which active components are loaded onto the surface or within the pores of a porous membrane. The numerous interconnected pores within the membrane provide effective loading sites for active components and reactant molecules. Compared to traditional batch reactions, flow-through chemical reactions based on catalytic membranes occur within the membrane pores. Due to shorter diffusion distances and thinner concentration boundary layers, mass transfer is more efficient. Furthermore, in reactions involving catalytic membranes, catalyst separation and recovery processes can be omitted, improving production efficiency and catalyst lifespan. MOFs, as a class of crystalline porous materials composed of alternating metal ions or small metal clusters and organic ligands, possess advantages such as high specific surface area and porous structure, and their pore structure is tunable and easily functionalized. These advantages make MOFs exhibit great potential in the field of catalysis, providing abundant resources and broad prospects for the development of novel, highly efficient catalytic materials. However, traditional catalytic membrane preparation mostly employs impregnation methods, which suffer from low active component loading and weak bonding between the active component and the membrane substrate, leading to easy deactivation of the catalytic membrane during later use. Summary of the Invention

[0004] This invention proposes a novel method for preparing multi-channel Ni / CM ceramic catalytic membranes, addressing the problems existing in traditional catalytic membrane preparation.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0006] A method for preparing a multi-channel Ni / CM ceramic catalytic membrane, comprising the following steps.

[0007] Step 1: Add 1,3,5-benzenetricarboxylic acid to a ternary mixed solvent of deionized water, N,N-dimethylformamide, and ethylene glycol, and stir thoroughly to dissolve, thus obtaining mixture A.

[0008] Step 2: Add nickel nitrate hexahydrate to mixture A and stir thoroughly to dissolve, thus obtaining mixture B.

[0009] Step 3: Immerse the pretreated ceramic membrane in mixed solution B and carry out a hydrothermal reaction under sealed conditions. After the reaction is completed, cool to room temperature. Take out the ceramic membrane and ultrasonically wash it with N,N-dimethylformamide and ethanol in sequence, and then vacuum dry it to obtain a multi-channel Ni-BTC / CM ceramic membrane.

[0010] Step 4: Calcine the multi-channel Ni-BTC / CM ceramic membrane in a hydrogen-argon mixed atmosphere to obtain the multi-channel Ni / CM ceramic catalytic membrane.

[0011] Preferably, the concentration of 1,3,5-benzenetricarboxylic acid in mixture A of step one is 0.02-0.03 mol / L; and the concentration of nickel nitrate hexahydrate in mixture B of step two is 0.035-0.065 mol / L.

[0012] Preferably, the pretreatment process of the ceramic membrane in step three is as follows: the ceramic membrane is placed in deionized water and boiled for 4-6 hours. After boiling, it is dried at 90-100℃ for at least 8 hours. The hydrothermal reaction temperature is 140-160℃ and the hydrothermal reaction time is 8-12 hours. The ultrasonic washing time with N,N-dimethylformamide is 10-16 minutes, the ultrasonic washing time with ethanol is 15-45 minutes, and the vacuum drying temperature is 75-85℃ for 10-14 hours.

[0013] Preferably, in step four, the volume fraction of hydrogen in the hydrogen-argon mixture is 8-11%, the calcination temperature is 400-470℃, the heating rate is 3-8℃ / min, and the calcination time after reaching the calcination temperature is 2-4h.

[0014] The present invention proposes that the multi-channel Ni / CM ceramic catalytic membrane prepared by the above method be applied to the selective hydrogenation reduction of p-nitrophenol to p-aminophenol.

[0015] The selective catalytic hydrogenation reduction of p-nitrophenol to p-aminophenol can be carried out in a batch or continuous manner. In a continuous reaction, the catalytic membrane remains stationary while the reaction solution is continuously fed in. After catalysis by the membrane, the reaction product is continuously output. No catalyst separation is required throughout the entire catalytic reaction. In a batch reaction, the catalytic membrane can be recycled and reused multiple times. Fresh reaction solution is added to the reactor, and the recycled multi-channel Ni / CM ceramic catalytic membrane is used for catalysis. The recycling method is as follows: after the reaction, the catalytic membrane is removed and soaked in deionized water for 20-40 minutes before direct use, without the need for additional catalyst separation.

[0016] This invention successfully loaded Ni-BTC onto the surface and pores of a multi-channel ceramic membrane substrate by altering the molar ratio of the organic ligand 1,3,5-benzenetricarboxylic acid to the metal source nickel nitrate hexahydrate, the hydrothermal temperature, the hydrothermal time, and the calcination temperature. Furthermore, calcination in a reducing atmosphere allowed for the in-situ formation of nickel nanoparticles on the ceramic membrane surface and within the pores, resulting in a highly efficient nickel-based catalytic membrane. In the high-temperature hydrothermal system, the gas pressure generated during the hydrothermal process allowed the precursor solution to permeate into the membrane pores under pressure. The pore size limitation enabled confined growth of Ni-BTC within the pores. Ni-BTC not only interacted with the membrane substrate through physical adsorption, but the nickel ions could also form coordination bonds with oxygen atoms in the membrane, resulting in more stable loading of Ni-BTC on the membrane surface and within the pores, preventing detachment. Moreover, the deposition of Ni-BTC in the membrane altered the microstructure of the membrane surface, forming a specific interface layer. Additionally, during the high-temperature calcination process, this specific interface layer formed on the precursor surface could migrate into the interior of the ceramic membrane substrate through surface diffusion. When the decomposition temperature of Ni-BTC on the membrane surface and within the pores is reached, the reducing hydrogen gas and carbon matrix simultaneously reduce nickel ions to elemental nickel in situ. Calcination in a reducing atmosphere strengthens the chemical bonds between the catalyst and the ceramic membrane, thereby enhancing their bonding strength. Furthermore, the dispersed nature of the membrane pores and the presence of numerous hydroxyl groups effectively prevent the migration of nickel nanoparticles, ensuring high dispersion of small-sized nickel nanoparticles on the membrane. Therefore, the nickel-based catalytic membrane preparation technology employed in this invention not only increases the loading of the active component on the membrane and enhances the bonding strength between the active component and the membrane, but also facilitates the formation of smaller, more dispersed nickel nanoparticles, thereby improving the catalytic performance of the membrane.

[0017] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0018] 1. This invention employs a hydrothermal method to directly grow Ni-BTC in situ on a multi-channel ceramic membrane substrate. The Ni / CM catalytic membrane formed by subsequent calcination exhibits excellent selective hydrogenation catalytic performance.

[0019] 2. The multi-channel Ni / CM ceramic catalytic membrane prepared by this invention has active component Ni nanoparticles on its surface and inside its pores, which greatly increases the loading of active component and thus improves catalytic efficiency.

[0020] 3. The multi-channel Ni / CM ceramic catalytic membrane prepared by this invention has excellent cycling stability, and its activity remains stable after multiple cyclic reactions. Attached Figure Description

[0021] Figure 1 This is a SEM image of the multichannel Ni / CM ceramic catalytic membrane prepared in Example 1.

[0022] Figure 2 The image shows the XRD pattern of the multichannel Ni / CM ceramic catalytic membrane prepared in Example 1.

[0023] Figure 3 The results show the cycle stability test results of the multichannel Ni / CM ceramic catalytic membrane prepared in Example 1. Detailed Implementation

[0024] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below with reference to specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0025] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0026] Example 1

[0027] This embodiment provides a specific preparation process for a multi-channel Ni / CM ceramic catalytic membrane.

[0028] (1) Preparation of Ni-BTC / CM film

[0029] First, prepare 150 mL of a mixed solvent of deionized water, N,N-dimethylformamide, and ethylene glycol in a volume ratio of 5:10:3. After thorough mixing, add 0.00375 mol of 1,3,5-benzenetricarboxylic acid and stir for 30 min at 25°C. Then, add 0.0075 mol of nickel nitrate hexahydrate and continue stirring for 15 min at 25°C. The stirring speed for all steps is 200 rpm. Pour the raw material solution into a polytetrafluoroethylene liner with a stainless steel shell and top cover. Place a multi-channel ceramic membrane (alumina, 19 channels, 8 cm length, 3 cm outer diameter, 1 μm average pore size) that has been boiled for 5 h and dried in a 95°C oven for 12 h on a separate plate. Assemble the stainless steel shell of the hydrothermal reactor that comes with the liner and tighten the top cover to seal it (other hydrothermal reactors that can achieve a seal can also be used). Then, place the entire sealed hydrothermal reactor in an oven preheated to 150°C for hydrothermal reaction for 10 h. After the reaction was completed, the membrane was naturally cooled to room temperature. The green Ni-BTC / CM membrane tube was then removed and immersed in N,N-dimethylformamide for ultrasonic washing for 13 min. After that, it was immersed in ethanol for ultrasonic washing for 30 min. After ultrasonic washing, the membrane tube was removed and vacuum dried at 80℃ for 12 h to obtain the Ni-BTC / CM membrane.

[0030] (2) Preparation of Ni / CM catalytic membrane

[0031] The dried Ni-BTC / CM membrane was placed in a tube furnace, sealed, and evacuated. A hydrogen-argon mixture with a hydrogen volume concentration of 10% was then introduced, and the temperature was increased from room temperature to 435°C at a rate of 5°C / min, and maintained at this temperature for 3 hours. After calcination, the membrane was allowed to cool naturally to room temperature, yielding a black Ni / CM catalytic membrane.

[0032] The selective catalytic hydrogenation reduction of p-nitrophenol to p-aminophenol was used as a model reaction, and the performance of the Ni / CM catalytic membrane was verified using a flow-through membrane reactor. A 240 mL solution of 0.03 mol / L p-nitrophenol (a mixture of ethanol and water in a 1:5 volume ratio) was prepared, and 0.4 mL of this solution was used as a control sample. 2.6 g of NaBH4 was added to the remaining reaction solution, and the mixture was magnetically stirred at room temperature for 3-7 min until the solid was completely dissolved. Simultaneously with the preparation of the reaction solution, the Ni / CM catalytic membrane was fixed inside the membrane module. A constant-temperature water bath was set to a target temperature of 35°C, and circulation was initiated, allowing constant-temperature water to enter the feed tank jacket and the membrane module jacket (the feed tank and membrane module are separate but connected by pipelines) to preheat the system. After preheating, the reaction solution was poured into the raw material tank. A peristaltic pump was used to deliver the reaction solution to the membrane reactor at a rate of 1.8 L / h. Timing began when the reaction solution circulated back to the raw material tank. 0.4 mL of the reaction solution was taken every 5 minutes, and its components were analyzed by high-performance liquid chromatography (HPLC). After the reaction was complete, the catalytic membrane was disassembled, soaked, and cleaned for subsequent use. HPLC was used to analyze the components of each sample, and the reactant conversion rate and product selectivity were calculated based on the standard curve. In this embodiment, after 25 minutes of reaction, the conversion rate of p-nitrophenol was 95.1%, and the selectivity of p-aminophenol was 100%.

[0033] Figure 1 The image shows a SEM image of the multichannel Ni / CM ceramic catalytic membrane in Example 1. The image shows the presence of particles on the ceramic membrane substrate, indicating that the active component was successfully loaded onto the multichannel ceramic membrane.

[0034] Figure 2 The XRD pattern of the powdered Ni / C catalyst corresponding to the multi-channel Ni / CM ceramic membrane in Example 1 is shown below. (Since the strong alumina diffraction peak of the ceramic membrane itself will mask the diffraction peak of Ni, the Ni / C catalyst prepared by calcining the Ni-BTC powder remaining in the reactor after the hydrothermal reaction was used for testing.) The diffraction peak appearing at 2θ of 26° belongs to the (002) crystal plane of graphite carbon. The diffraction peaks appearing at 2θ of 44.5°, 51.8° and 76.4° belong to the (111), (200) and (220) crystal planes of Ni. The weak diffraction peak appearing at 2θ of 62.6° belongs to the (220) crystal plane of NiO.

[0035] Example 2

[0036] This embodiment provides the preparation process of the Ni / CM catalytic membrane and its application in the selective catalytic hydrogenation reduction of p-nitrophenol to p-aminophenol. Unless otherwise specified, this embodiment is consistent with Example 1.

[0037] (1) Preparation of Ni-BTC / CM film

[0038] First, prepare 150 mL of a mixed solvent of deionized water, N,N-dimethylformamide, and ethylene glycol in a volume ratio of 5:10:3. After thorough mixing, add 0.003 mol of 1,3,5-benzenetricarboxylic acid and stir for 35 min at a water bath temperature of 20°C. Then, add 0.00525 mol of nickel nitrate hexahydrate and continue stirring for 20 min at a water bath temperature of 20°C. The stirring speed for all steps is 200 rpm. Pour the raw material solution into a polytetrafluoroethylene liner with a stainless steel shell and a top cover. Place a multi-channel ceramic membrane (zirconia, 19 channels, 8 cm length, 3 cm outer diameter, 1 μm average pore size) that has been boiled for 4 h and dried in a 90°C oven for 12 h on a separate plate. Assemble the stainless steel shell of the hydrothermal reactor that comes with the liner and tighten the top cover to seal it (other hydrothermal reactors that can achieve a seal can also be used). Then, place the entire sealed hydrothermal reactor in an oven preheated to 140°C for hydrothermal reaction for 12 h. After the reaction was completed, the membrane was naturally cooled to room temperature. The green Ni-BTC / CM membrane tube was then removed and immersed in N,N-dimethylformamide for ultrasonic washing for 10 min, followed by immersion in ethanol for ultrasonic washing for 15 min. After ultrasonic washing, the membrane tube was removed and vacuum dried at 75°C for 14 h to obtain the Ni-BTC / CM membrane.

[0039] (2) Preparation of Ni / CM catalytic membrane

[0040] The dried Ni-BTC / CM membrane was placed in a tube furnace, sealed, and evacuated. A hydrogen-argon mixture with a hydrogen volume concentration of 11% was then introduced, and the temperature was increased from room temperature to 400°C at a rate of 3°C / min. This temperature was maintained for 4 hours. After calcination, the membrane was allowed to cool naturally to room temperature, resulting in a black Ni / CM catalytic membrane.

[0041] The Ni / CM catalytic membrane prepared in this example was used to catalyze the hydrogenation reduction of p-nitrophenol to p-aminophenol, and the reactants were the same as in Example 1. After 25 min of reaction, the conversion rate of p-nitrophenol was 90.5%, and the selectivity of p-aminophenol was 100%.

[0042] Example 3

[0043] This embodiment provides the preparation process of the Ni / CM catalytic membrane and its application in the selective catalytic hydrogenation reduction of p-nitrophenol to p-aminophenol. Unless otherwise specified, this embodiment is consistent with Example 1.

[0044] (1) Preparation of Ni-BTC / CM film

[0045] First, prepare 150 mL of a mixed solvent of deionized water, N,N-dimethylformamide, and ethylene glycol in a volume ratio of 5:10:3. After thorough mixing, add 0.0045 mol of 1,3,5-benzenetricarboxylic acid and stir for 25 min at a water bath temperature of 30°C. Then, add 0.00975 mol of nickel nitrate hexahydrate and continue stirring for 10 min at a water bath temperature of 30°C. The stirring speed for all steps is 200 rpm. Pour the raw material solution into a polytetrafluoroethylene liner with a stainless steel shell and a top cover. Place a multi-channel ceramic membrane (alumina, 37 channels, 8 cm length, 3 cm outer diameter, 1 μm average pore size) that has been boiled for 6 h and dried in a 100°C oven for 12 h on a top cover. Assemble the stainless steel shell of the hydrothermal reactor that comes with the liner and tighten the top cover to seal it (other hydrothermal reactors that can achieve a seal can also be used). Then, place the entire sealed hydrothermal reactor in an oven preheated to 160°C for hydrothermal reaction for 8 h. After the reaction was completed, the green Ni-BTC / CM membrane tube was naturally cooled to room temperature and removed. The membrane tube was then immersed in N,N-dimethylformamide and ultrasonically washed for 16 min, followed by immersion in ethanol and ultrasonically washed for 45 min. After ultrasonic washing, the membrane tube was removed and vacuum dried at 85 °C for 10 h to obtain the Ni-BTC / CM membrane.

[0046] (2) Preparation of Ni / CM catalytic membrane

[0047] The dried Ni-BTC / CM membrane was placed in a tube furnace, sealed, and evacuated. A hydrogen-argon mixture with a hydrogen volume concentration of 8% was then introduced, and the temperature was increased from room temperature to 470°C at a rate of 7°C / min, and maintained at this temperature for 2 hours. After calcination, the membrane was allowed to cool naturally to room temperature, yielding a black Ni / CM catalytic membrane.

[0048] Tests showed that when the membrane tube prepared in this embodiment was used for catalysis, the conversion rate of p-nitrophenol was 86.3% and the selectivity of p-aminophenol was 100% after 25 minutes of reaction.

[0049] Example 4

[0050] This embodiment uses the catalytic membrane from Example 1 for multiple cycles to verify its cyclic stability. After each reaction, the membrane tube is removed, immersed in deionized water for 30 minutes, and then it can be reused. The results are as follows: Figure 3 As shown, after 25 minutes of each reaction, except for the first reaction where the conversion rate of p-nitrophenol was slightly lower, the conversion rates of the other six reactions all reached 100% (after the first reaction, some nickel oxide was reduced to zero-valent nickel by sodium borohydride, and the catalytic membrane had excellent stability, so the catalytic activity of the recovered catalytic membrane was actually higher than that of the fresh catalytic membrane). After 7 cycles, the catalytic membrane showed no obvious deactivation and good stability.

[0051] Comparative Example 1

[0052] The difference between this comparative example and Example 1 lies in the different hydrothermal reaction temperatures during the preparation of the catalytic membrane, in order to verify the influence of hydrothermal temperature on the performance of the catalytic membrane within the scope of protection of this invention.

[0053] (1) Preparation of Ni-BTC / CM film

[0054] First, prepare 150 mL of a mixed solvent of deionized water, N,N-dimethylformamide, and ethylene glycol in a volume ratio of 5:10:3. After thorough mixing, add 0.00375 mol of 1,3,5-benzenetricarboxylic acid and stir for 30 min at 25°C. Then, add 0.0075 mol of nickel nitrate hexahydrate and continue stirring for 15 min at 25°C. The stirring speed for all steps is 200 rpm. Pour the raw material solution into a polytetrafluoroethylene liner with a stainless steel shell and lid. Place a multi-channel ceramic membrane (alumina, 19 channels, 8 cm length, 3 cm diameter, 1 μm average pore size) that has been boiled for 5 h and dried in a 95°C oven for 12 h on a separate plate. Assemble the stainless steel shell of the hydrothermal reactor (which comes with the liner) and tighten the lid for sealing (other hydrothermal reactors capable of sealing can also be used). Then, place the entire sealed hydrothermal reactor in an oven preheated to 110°C for hydrothermal reaction for 10 h. After the reaction was completed, the green Ni-BTC / CM membrane tube was naturally cooled to room temperature and removed. The membrane tube was then immersed in N,N-dimethylformamide and ultrasonically washed for 13 min, followed by immersion in ethanol and ultrasonically washed for 30 min. After ultrasonic washing, the membrane tube was removed and vacuum dried at 80 °C for 12 h to obtain the Ni-BTC / CM membrane.

[0055] (2) Preparation of Ni / CM catalytic membrane

[0056] The dried Ni-BTC / CM membrane was placed in a tube furnace, sealed, and evacuated. A hydrogen-argon mixture with a hydrogen volume concentration of 10% was then introduced, and the temperature was increased from room temperature to 435°C at a rate of 5°C / min, and maintained at this temperature for 3 hours. After calcination, the membrane was allowed to cool naturally to room temperature, yielding a black Ni / CM catalytic membrane.

[0057] The results showed that after 25 minutes of reaction, the conversion rate of p-nitrophenol was 37.9% and the selectivity of p-aminophenol was 100%.

[0058] Comparative Example 2

[0059] The difference between this comparative example and Example 1 is the calcination temperature, in order to verify the effect of calcination temperature on the performance of the catalytic membrane within the scope of protection of this invention.

[0060] (1) Preparation of Ni-BTC / CM film

[0061] First, prepare 150 mL of a mixed solvent of deionized water, N,N-dimethylformamide, and ethylene glycol in a volume ratio of 5:10:3. After thorough mixing, add 0.00375 mol of 1,3,5-benzenetricarboxylic acid and stir for 30 min at 25°C. Then, add 0.0075 mol of nickel nitrate hexahydrate and continue stirring for 15 min at 25°C. The stirring speed for all steps is 200 rpm. Pour the raw material solution into a polytetrafluoroethylene liner with a stainless steel shell and lid. Place a multi-channel ceramic membrane (alumina, 19 channels, 8 cm length, 3 cm diameter, 1 μm average pore size) that has been boiled for 5 h and dried in a 95°C oven for 12 h on a separate plate. Assemble the stainless steel shell of the hydrothermal reactor attached to the liner and tighten the lid for sealing (other hydrothermal reactors capable of sealing can also be used). Then, place the entire sealed hydrothermal reactor in an oven preheated to 150°C for hydrothermal reaction for 10 h. After the reaction was completed, the green Ni-BTC / CM membrane tube was naturally cooled to room temperature and removed. The membrane tube was then immersed in N,N-dimethylformamide and ultrasonically washed for 13 min, followed by immersion in ethanol and ultrasonically washed for 30 min. After ultrasonic washing, the membrane tube was removed and vacuum dried at 80 °C for 12 h to obtain the Ni-BTC / CM membrane.

[0062] (2) Preparation of Ni / CM catalytic membrane

[0063] The dried Ni-BTC / CM membrane was placed in a tube furnace, sealed, and evacuated. A hydrogen-argon mixture with a hydrogen volume concentration of 10% was then introduced, and the temperature was increased from room temperature to 335°C at a rate of 5°C / min, and maintained at this temperature for 3 hours. After calcination, the membrane was allowed to cool naturally to room temperature, yielding a black Ni / CM catalytic membrane.

[0064] The results showed that after 25 minutes of reaction, the conversion rate of p-nitrophenol was 21.2% and the selectivity of p-aminophenol was 100%.

[0065] Comparative Example 3

[0066] The difference between this comparative example and Example 1 is that the hydrogen volume concentration in the calcination atmosphere is different, in order to verify the effect of hydrogen volume concentration on the performance of the catalytic membrane within the scope of protection of this invention.

[0067] (1) Preparation of Ni-BTC / CM film

[0068] First, prepare 150 mL of a mixed solvent of deionized water, N,N-dimethylformamide, and ethylene glycol in a volume ratio of 5:10:3. After thorough mixing, add 0.00375 mol of 1,3,5-benzenetricarboxylic acid and stir for 30 min at 25°C. Then, add 0.0075 mol of nickel nitrate hexahydrate and continue stirring for 15 min at 25°C. The stirring speed for all steps is 200 rpm. Pour the raw material solution into a polytetrafluoroethylene liner with a stainless steel shell and lid. Place a multi-channel ceramic membrane (alumina, 19 channels, 8 cm length, 3 cm diameter, 1 μm average pore size) that has been boiled for 5 h and dried in a 95°C oven for 12 h on a separate plate. Assemble the stainless steel shell of the hydrothermal reactor attached to the liner and tighten the lid for sealing (other hydrothermal reactors capable of sealing can also be used). Then, place the entire sealed hydrothermal reactor in an oven preheated to 150°C for hydrothermal reaction for 10 h. After the reaction was completed, the green Ni-BTC / CM membrane tube was naturally cooled to room temperature and removed. The membrane tube was then immersed in N,N-dimethylformamide and ultrasonically washed for 13 min, followed by immersion in ethanol and ultrasonically washed for 30 min. After ultrasonic washing, the membrane tube was removed and vacuum dried at 80 °C for 12 h to obtain the Ni-BTC / CM membrane.

[0069] (2) Preparation of Ni / CM catalytic membrane

[0070] The dried Ni-BTC / CM membrane was placed in a tube furnace, sealed, and evacuated. A hydrogen-argon mixture with a hydrogen volume concentration of 40% was then introduced, and the temperature was increased from room temperature to 435°C at a rate of 5°C / min, and maintained at this temperature for 3 hours. After calcination, the membrane was allowed to cool naturally to room temperature, yielding a black Ni / CM catalytic membrane.

[0071] The results showed that after 25 minutes of reaction, the conversion rate of p-nitrophenol was 34.3% and the selectivity of p-aminophenol was 100%.

[0072] Comparative Example 4

[0073] The difference between this comparative example and Example 1 is that the multi-channel ceramic membrane substrate used in the preparation process was not boiled; the remaining steps were the same as in Example 1. After 25 minutes of reaction, the conversion rate of p-nitrophenol was 69.8%, and the selectivity for p-aminophenol was 100%. This demonstrates that whether the membrane substrate used in the catalytic membrane preparation is boiled significantly affects its catalytic performance. Boiling removes excess impurities from the membrane surface and pores, which is beneficial for the growth of Ni-BTC on the membrane, thereby increasing the loading of the active component on the membrane.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a multi-channel Ni / CM ceramic catalytic membrane, characterized in that, The steps are as follows: Step 1: Add 1,3,5-benzenetricarboxylic acid to a ternary mixed solvent of deionized water, N,N-dimethylformamide, and ethylene glycol, and stir thoroughly to dissolve, to obtain mixture A; Step 2: Add nickel nitrate hexahydrate to mixture A and stir thoroughly to dissolve, obtaining mixture B; Step 3: Immerse the pretreated ceramic membrane in mixed solution B and carry out a hydrothermal reaction under sealed conditions. After the reaction is completed, cool to room temperature. Take out the ceramic membrane and ultrasonically wash it with N,N-dimethylformamide and ethanol in sequence, and vacuum dry it to obtain a multi-channel Ni-BTC / CM ceramic membrane. Step 4: The multi-channel Ni-BTC / CM ceramic membrane is calcined in a hydrogen-argon mixed atmosphere to obtain a multi-channel Ni / CM ceramic catalytic membrane; The concentration of 1,3,5-benzenetricarboxylic acid in mixture A of step one is 0.02-0.03 mol / L; the concentration of nickel nitrate hexahydrate in mixture B of step two is 0.035-0.065 mol / L. The pretreatment process of the ceramic membrane in step three is as follows: place the ceramic membrane in deionized water and boil it for 4-6 hours. After boiling, dry it at 90-100℃ for at least 8 hours. The hydrothermal reaction temperature is 140-160℃ and the hydrothermal reaction time is 8-12 hours. The ultrasonic washing time with N,N-dimethylformamide is 10-16 minutes, the ultrasonic washing time with ethanol is 15-45 minutes, and the vacuum drying temperature is 75-85℃ for 10-14 hours. In step four, the volume fraction of hydrogen in the hydrogen-argon mixture is 8-11%. The calcination temperature is 400-470℃, and the calcination time is 2-4 hours.

2. The multi-channel Ni / CM ceramic catalytic membrane prepared by the method in claim 1 is used in the selective hydrogenation reduction of p-nitrophenol to p-aminophenol.

3. The application according to claim 2, characterized in that, The selective catalytic hydrogenation reduction of p-nitrophenol to p-aminophenol can be carried out in either batch or continuous processes.

4. The application according to claim 3, characterized in that, Catalysis was carried out using a recycled multi-channel Ni / CM ceramic catalytic membrane. The recycling method was as follows: after the reaction was completed, the catalytic membrane was taken out and soaked in deionized water for 20-40 minutes.

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