A method for preparing a multi-channel Ni / CM ceramic catalytic membrane
By preparing a multi-channel Ni/CM ceramic catalytic membrane, the problem of low utilization rate of precious metal active components was solved, achieving high efficiency and stable catalytic performance, reducing production costs, and making it suitable for industrial applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING TECH UNIV
- Filing Date
- 2025-04-07
- Publication Date
- 2026-06-16
AI Technical Summary
Traditional catalytic membranes have low utilization rates of precious metal active components, resulting in high production costs and making industrial-scale production difficult.
A multi-channel Ni/CM ceramic catalytic membrane was prepared by controlling the molar ratio of the organic ligand 2-aminoterephthalic acid to the metal source nickel nitrate hexahydrate, the hydrothermal temperature, and the calcination temperature to prepare Ni-MOF-NH2 derived metal-carbon-nitrogen composite material. This method enables in-situ growth and uniform distribution of Ni-MOF-NH2 within the membrane pores, avoids metal agglomeration, and improves the utilization rate of active components.
It improves the utilization rate of metallic Ni, reduces the production cost of the catalytic membrane, and the catalytic membrane has high activity and good stability, making it suitable for large-scale industrial applications.
Smart Images
Figure CN120243027B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of ceramic catalytic membrane technology, and relates to a method for preparing a multi-channel Ni / CM ceramic catalytic membrane. Background Technology
[0002] p-Nitrophenol is a common organic pollutant in the production of dyes, pesticides, plasticizers, and herbicides. Hydrogenating it to p-aminophenol can effectively treat related pollution. However, due to the high concentration, recalcitrant nature, and toxicity of phenol-containing wastewater, traditional physical, chemical, and biochemical treatment methods face difficulties in meeting the technical and economic requirements for organic pollutant degradation. While precious metal catalysts typically exhibit excellent performance in catalytic processes, their high cost and tendency to be lost during the reaction significantly increase production costs, hindering industrial-scale production.
[0003] Catalytic membranes, constructed by loading active components onto a membrane support, are the core of membrane catalysis. They enable complete separation of the catalyst from the reaction medium, simplifying the process. Furthermore, the membrane pores improve mass transfer within the membrane, ensuring uniform distribution of reactants and enhancing catalytic efficiency. However, the utilization rate of precious metal active components in catalytic membranes still needs improvement. Summary of the Invention
[0004] This invention addresses the problem of low utilization rate of precious metal active components in traditional catalytic membranes by proposing a method for preparing a multi-channel Ni / CM ceramic catalytic membrane.
[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] (1) Add 2-aminoterephthalic acid to N,N-dimethylformamide and mix well to obtain solution A.
[0008] (2) Slowly add solution A to the aqueous solution of nickel nitrate hexahydrate and mix well to obtain solution B.
[0009] (3) Immerse the membrane tube in the mixed solution B and carry out the hydrothermal synthesis reaction. After the reaction is completed, cool, wash and dry to obtain a multi-channel Ni-MOF-NH2 / CM ceramic membrane.
[0010] (4) Calcination and cooling yielded the catalytic membrane C.
[0011] (5) Sodium borohydride is added to an aqueous ethanol solution and mixed evenly to obtain a reduction rinsing solution. The reduction rinsing solution is forced to circulate through the pores of the catalytic membrane C to carry out the reduction reaction and obtain a multi-channel Ni / CM ceramic catalytic membrane.
[0012] Preferably, the concentration of 2-aminoterephthalic acid in solution A in step (1) is 0.1-0.5 mol / L; the concentration of the aqueous solution of nickel nitrate hexahydrate in step (2) is 0.01-0.04 mol / L, and the temperature of the aqueous solution of nickel nitrate hexahydrate is maintained at 20-40℃ during the slow dropwise addition.
[0013] Preferably, the hydrothermal synthesis reaction temperature in step (3) is 150-170℃ and the hydrothermal synthesis time is 10-12h.
[0014] Preferably, the calcination atmosphere in step (4) is argon, the calcination temperature is 350-600℃, and the calcination time is 2-5h.
[0015] Preferably, in step (5), the concentration of sodium borohydride in the reduction rinsing solution is 9-11 g / L, the volume ratio of ethanol to water in the ethanol solution is 1:5, and the flow rate of the reduction rinsing solution through the membrane pores is 0.3-0.5 cm / min.
[0016] This invention proposes the application of the multi-channel Ni / CM ceramic catalytic membrane prepared by the above method in the hydrogenation of p-nitrophenol to p-aminophenol. The reaction process can be batch or continuous. During the reaction, the reaction solution is forced to flow through the pores of the multi-channel Ni / CM ceramic catalytic membrane and flows out from the sidewall of the membrane to complete the reaction. The multi-channel Ni / CM ceramic catalytic membrane prepared by this invention has good stability. After the reaction, the membrane pores are rinsed with ethanol for 5-10 minutes, and then the ceramic membrane is removed, dried or air-dried, and can be used with fresh raw materials.
[0017] This invention effectively prepares Ni-MOF-NH2-derived metal-carbon-nitrogen composite materials with high-efficiency utilization of nickel by controlling the molar ratio of the organic ligand 2-aminoterephthalic acid to the metal source nickel nitrate hexahydrate, the hydrothermal temperature, hydrothermal time, and calcination temperature. With increasing concentrations of the organic ligand 2-aminoterephthalic acid and the metal source nickel nitrate hexahydrate feed solution, the Ni loading initially increases and then remains essentially constant. The carbonization of the organic ligand during the thermal decomposition of MOFs effectively prevents metal agglomeration, and the pyridine nitrogen generated during pyrolysis facilitates reactant conversion. In the high-temperature hydrothermal system, the gradually increasing pressure during hydrothermal processing allows the precursor to permeate into the membrane pores under pressure, thereby achieving in-situ growth of Ni-MOF-NH2 on a multi-channel ceramic membrane. The amino groups in the Ni-MOF-NH2 precursor can serve as a nitrogen source and anchoring site for Ni NPs, facilitating electron transport and effectively inhibiting the loss of active components. Furthermore, due to the electron-withdrawing properties of amino groups, the electron-donating Lewis basic nitrogen-containing groups on the carbon matrix selectively adsorb p-nitrophenol, thus exhibiting excellent catalytic performance.
[0018] Compared with the prior art, the advantages and positive effects of the present invention are as follows:
[0019] 1. The process proposed in this invention enables Ni-MOF-NH2 to grow fully within the membrane pores, increasing the active components and ensuring uniform distribution of the active components, thereby effectively improving the utilization rate of metallic Ni and reducing the production cost of the catalytic membrane.
[0020] 2. The preparation process of this invention is simple and controllable, the catalytic membrane has high activity and good stability, and the recovery is simple and convenient, making it suitable for large-scale industrial application and promotion. Attached Figure Description
[0021] Figure 1 This is a SEM image of the multichannel Ni / CM ceramic catalytic membrane in Example 1.
[0022] Figure 2 The image shows the XRD pattern of the multichannel Ni / CM ceramic catalytic membrane in Example 1.
[0023] Figure 3 The results show the stability test results of the multi-channel Ni / CM ceramic catalytic membrane 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] Prepare 10 mL of a 0.3 M N,N-dimethylformamide (DMF) solution of 2-aminoterephthalic acid and 130 mL of a 0.024 M nickel nitrate hexahydrate aqueous solution. While stirring, slowly add the 2-aminoterephthalic acid solution dropwise to the nickel nitrate hexahydrate aqueous solution at 35°C over approximately 5 minutes. Continue stirring at 200 rpm for 30 minutes in a 35°C water bath to obtain the feed solution. Vertically place a commercially available alumina ceramic membrane (19 channels, 8 cm length, 3 cm outer diameter, 1000 nm pore size) into a polytetrafluoroethylene liner with a stainless steel shell and top cover. Slowly pour the feed solution into the membrane tube from the top until it completely submerges the ceramic membrane. Seal the top cover and place the sealed hydrothermal reactor in an oven preheated to 160°C for hydrothermal reaction for 10 hours. After the reaction was completed, the hydrothermal reactor was removed and allowed to cool naturally to room temperature. The brown Ni-MOF-NH2 / CM membrane tube was then removed. The membrane tube was first immersed in DMF and ultrasonically washed for 5 min, and then immersed in ethanol and ultrasonically washed for 5 min. After ultrasonic washing, it was removed and dried at 70℃ for 10 h to obtain the Ni-MOF-NH2 / CM membrane.
[0029] The dried Ni-MOF-NH2 / CM membrane was placed in a tube furnace and calcined at an initial temperature (room temperature) to 435°C, and held at the target temperature of 435°C for 3 hours. The heating rate was 5°C / min, and the calcination atmosphere was argon. After calcination, the membrane was naturally cooled to room temperature to obtain a gray-black Ni / CM catalytic membrane.
[0030] The Ni / CM catalytic membrane was vertically fixed and preheated at 35°C. 240 ml of a 9 g / L sodium borohydride solution (a mixture of ethanol and water in a volume ratio of 1:5) was prepared. After preheating at 35°C, the solution was forced to circulate from bottom to top into the membrane tube (the upper end of the membrane tube was sealed by the membrane module) using a peristaltic pump and flowed out from the side wall of the catalytic membrane to pre-reduce the catalytic membrane. The sodium borohydride solution was circulated at a flow rate of 0.38 cm / min through the membrane pores for 40 min.
[0031] After the sodium borohydride solution undergoes forced flow, prepare 240 mL of a 0.03 mol / L p-nitrophenol solution (using a 1:5 volume ratio of ethanol to water). Take 0.4 mL of this p-nitrophenol solution as the initial sample. Add 2.6 g of NaBH4 to the remaining p-nitrophenol solution and stir magnetically for 3-5 min at room temperature until the NaBH4 is completely dissolved. Then pour the reaction solution into the feed tank, seal the top of the catalytic membrane, and use a peristaltic pump and tubing to control the flow rate of the reaction solution from bottom to top into the membrane tube at 3.3 L / h, flowing out from the side wall of the catalytic membrane and then circulating back into the feed tank. Start timing when the reaction solution circulates back into the feed tank. Take 0.4 mL of the reaction solution at 5 min, 10 min, 20 min, 30 min, and 40 min for liquid chromatography analysis. After the reaction is complete, rinse the catalytic membrane with ethanol under forced flow for 5-10 min for subsequent use. High-performance liquid chromatography (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 40 minutes of reaction, the conversion rate of p-nitrophenol was 89.1%, and the selectivity of p-aminophenol was 100%.
[0032] Powder was scraped from the inner and outer walls of the catalyst membrane for testing. Figure 1 This is a SEM image of the multi-channel Ni / CM ceramic catalytic membrane obtained in this embodiment. Figure 1 The presence of particles on the ceramic membrane substrate indicates that the active components have been successfully loaded onto the multichannel ceramic membrane.
[0033] Figure 2 The XRD patterns obtained by scraping powder from the inner and outer walls of the multi-channel Ni / CM ceramic catalytic membrane obtained in this embodiment show diffraction peaks at 44.5°, 51.8° and 76.4°, respectively, which correspond to the (111), (200) and (220) crystal planes of metallic Ni. This indicates that Ni is reduced to 0-valent Ni during pyrolysis and serves as an active center.
[0034] Example 2
[0035] Unless otherwise specified, this embodiment and the following embodiments are consistent with Embodiment 1.
[0036] Prepare 10 mL of a 0.45 M DMF solution of 2-aminoterephthalic acid and 130 mL of a 0.036 M aqueous solution of nickel nitrate hexahydrate. While stirring, slowly add the 2-aminoterephthalic acid solution dropwise to the nickel nitrate hexahydrate solution, and continue stirring for 30 min at a water bath temperature of 30°C and a stirring rate of 200 rpm to obtain the feed solution. Vertically place the multi-channel ceramic membrane into a polytetrafluoroethylene liner with a stainless steel outer shell and a top cover. Then, slowly pour the feed solution from the top of the membrane tube until the ceramic membrane is completely submerged. Seal the top cover, and then place the entire sealed hydrothermal reactor in an oven preheated to 150°C for hydrothermal reaction for 12 h. After the reaction was completed, the hydrothermal reactor was removed and allowed to cool naturally to room temperature. The brown Ni-MOF-NH2 / CM membrane tube was then removed. The membrane tube was first immersed in DMF and ultrasonically washed for 10 min, and then immersed in ethanol and ultrasonically washed for 10 min. After ultrasonic washing, it was removed and dried at 80℃ for 10 h to obtain the Ni-MOF-NH2 / CM membrane.
[0037] The dried Ni-MOF-NH2 / CM membrane was placed in a tube furnace and calcined at an initial temperature (room temperature) to 350℃, and held at the target temperature of 350℃ for 5 hours. The heating rate was 3℃ / min, and the calcination atmosphere was argon. After calcination, the membrane was allowed to cool naturally to room temperature, yielding a grayish-black Ni / CM catalytic membrane. 240 ml of a 11 g / L sodium borohydride solution (a mixture of ethanol and water in a 1:5 volume ratio) was prepared and forced through the membrane pores at a flow rate of 0.35 cm / min for 35 minutes to pre-reduce the catalytic membrane.
[0038] The Ni / CM catalytic membrane prepared in this example was used to catalyze the hydrogenation reduction of p-nitrophenol to p-aminophenol. The reaction materials and operating procedures were the same as in Example 1. After 40 min of reaction, the conversion rate of p-nitrophenol was 86.4%, and the selectivity of p-aminophenol was 100%.
[0039] Example 3
[0040] Prepare 10 mL of a 0.15 M DMF solution of 2-aminoterephthalic acid and 130 mL of a 0.012 M aqueous solution of nickel nitrate hexahydrate. Slowly add the 2-aminoterephthalic acid solution dropwise to the nickel nitrate hexahydrate solution while stirring. Continue stirring for 25 min at a water bath temperature of 25°C and a stirring rate of 200 rpm to obtain the feed solution. Place the multi-channel ceramic membrane vertically into a polytetrafluoroethylene liner with a stainless steel outer shell and a top cover. Then, slowly pour the feed solution from the top of the membrane tube until it completely submerges the ceramic membrane. Seal the container with the top cover and place the sealed hydrothermal reactor in an oven preheated to 170°C for hydrothermal reaction for 8 h. After the reaction was completed, the hydrothermal reactor was removed and allowed to cool naturally to room temperature. The brown Ni-MOF-NH2 / CM membrane tube was then removed. The membrane tube was first immersed in DMF and ultrasonically washed for 5 min, and then immersed in ethanol and ultrasonically washed for 5 min. After ultrasonic washing, it was removed and dried at 60℃ for 12 h to obtain the Ni-MOF-NH2 / CM membrane.
[0041] The dried Ni-MOF-NH2 / CM membrane was placed in a tube furnace and calcined at an initial temperature (room temperature) to 600℃, and held at the target temperature of 600℃ for 2 hours. The heating rate was 5℃ / min, and the calcination atmosphere was argon. After calcination, the membrane was allowed to cool naturally to room temperature, yielding a grayish-black Ni / CM catalytic membrane. 240 ml of a 10 g / L sodium borohydride solution (using a 1:5 volume ratio of ethanol to water) was prepared and forced to flow through the membrane at a flow rate of 0.41 cm / min for 30 minutes to pre-reduce the catalytic membrane.
[0042] 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 40 min of reaction, the conversion rate of p-nitrophenol was 85.3%, and the selectivity of p-aminophenol was 100%.
[0043] Example 4
[0044] This embodiment uses the Ni / CM catalytic membrane from Example 1 for multiple cycles to verify the cyclic stability of the catalytic membrane. After each reaction, the membrane tube is removed, and ethanol is forced to flow from bottom to top into the membrane tube under the action of a peristaltic pump, and then flows out from the side wall of the catalytic membrane to rinse the membrane tube for 5 minutes. Afterward, it can be reused, with a rinsing rate of 2 L / h. The results are as follows... Figure 3 As shown, samples were taken for testing after each reaction lasted 40 minutes. Experimental verification showed that the Ni / CM catalytic membrane in Example 1, after being used in Example 1, was recycled five times (numbered sequentially 1-5), and the conversion rate of the reaction remained at about 90%. The catalytic membrane showed no obvious deactivation during the five cycles, indicating good stability.
[0045] Comparative Example 1
[0046] The difference between this comparative example and Example 1 is that 2-aminoterephthalic acid was replaced with terephthalic acid, while the rest of the preparation process and conditions remained unchanged. The conversion rate of p-nitrophenol was 66.5% and the selectivity was 100% after 40 minutes of reaction.
[0047] Comparative Example 2
[0048] The difference between this comparative example and Example 1 is that 2-aminoterephthalic acid was replaced with melamine, while the rest of the preparation process and conditions remained unchanged. The conversion rate was 30.6% and the selectivity was 100% after 40 minutes of reaction.
[0049] Comparative Example 3
[0050] The difference between this comparative example and Example 1 is the calcination temperature. The dried Ni-MOF-NH2 / CM membrane was calcined at a target temperature of 850°C for 3 hours to prepare the Ni / CM catalytic membrane.
[0051] The remaining preparation process and conditions remained unchanged. The conversion rate was 60.6% and the selectivity was 100% after 40 minutes of reaction.
[0052] Comparative Example 4
[0053] The difference between this comparative example and Example 1 lies in the hydrothermal temperature. The entire sealed hydrothermal reactor was placed in an oven preheated to 120°C for 10 hours of hydrothermal reaction. All other preparation processes and conditions remained unchanged. Testing showed that the conversion rate was 58.9% and the selectivity was 100% after 40 minutes of reaction.
[0054] 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: (1) Add 2-aminoterephthalic acid to N,N-dimethylformamide and mix well to obtain solution A; (2) Slowly add solution A dropwise to the aqueous solution of nickel nitrate hexahydrate and mix well to obtain solution B; (3) Immerse the membrane tube in the mixed solution B and carry out the hydrothermal synthesis reaction. After the reaction is completed, cool, wash and dry to obtain a multi-channel Ni-MOF-NH2 / CM ceramic membrane. (4) Calcination and cooling yield catalytic membrane C; (5) Sodium borohydride is added to an ethanol solution and mixed evenly to obtain a reduction rinsing solution. The reduction rinsing solution is forced to circulate through the membrane pores of the catalyst membrane C to carry out a reduction reaction and obtain a multi-channel Ni / CM ceramic catalyst membrane. In step (4), the calcination atmosphere is argon, the calcination temperature is 350-600℃, and the calcination time is 2-5h.
2. The method for preparing the multi-channel Ni / CM ceramic catalytic membrane according to claim 1, characterized in that, In step (1), the concentration of 2-aminoterephthalic acid in solution A is 0.1-0.5 mol / L; in step (2), the concentration of the aqueous solution of nickel nitrate hexahydrate is 0.01-0.04 mol / L, and the temperature of the aqueous solution of nickel nitrate hexahydrate is maintained at 20-40℃ during the slow droplet addition.
3. The method for preparing the multi-channel Ni / CM ceramic catalytic membrane according to claim 1, characterized in that, Step (3) The hydrothermal synthesis reaction temperature is 150-170℃, and the hydrothermal synthesis time is 10-12h.
4. The method for preparing the multi-channel Ni / CM ceramic catalytic membrane according to claim 1, characterized in that, In step (5), the concentration of sodium borohydride in the reduction rinsing solution is 9-11 g / L, the volume ratio of ethanol to water in the ethanol solution is 1:5, and the flow rate of the reduction rinsing solution through the membrane pores is 0.3-0.5 cm / min.
5. The application of the multi-channel Ni / CM ceramic catalytic membrane prepared by the method according to any one of claims 1-4 in the hydrogenation of p-nitrophenol to p-aminophenol.