A porous cationic material with single-point anchoring of chloroplatinic acid anions and its preparation method and application

Abstract

The present invention belongs to the field of porous material preparation and provides a method for preparing a porous cationic material with a single-point anchored chloroplatinic acid anion. The method comprises the following steps: S1: condensing pyrone with an active methylene monomer, Knoevenagel, to obtain a pyranonitrile intermediate 1; S2: condensing pyranonitrile intermediate 1 with an aldehyde derivative, Knoevenagel, to obtain a pyranonitrile intermediate 2; S3: heating and refluxing pyranonitrile intermediate 2 with an oxidant, FeCl3, to obtain porous material 1; S4: reacting porous material 1 with a quaternary ammonium salt to obtain porous cationic material 2, and reacting porous cationic material 2 with a platinum reagent to obtain a porous cationic material with a single-point anchored chloroplatinic acid anion. The preparation method provided by the present invention has mild reaction conditions and simple operation. The prepared product has an adjustable specific surface area, good thermal stability, and excellent photocatalytic reduction ability, and has potential application prospects in treating p-nitrophenol wastewater.

Description

Technical Field

[0001] The invention belongs to the field of preparation of porous materials, and in particular relates to a porous cationic material for single-point anchoring of chloroplatinic acid anions, a preparation method and an application thereof. Background Art

[0002] Over the past few decades, with the rapid development of the petroleum industry, the inadvertent leakage of petroleum and various organic substances derived from it during extraction, transportation and storage has caused great harm to marine and terrestrial ecosystems. Nitrophenol is a harmful, non-biodegradable toxic compound that causes many diseases. 4-Nitrophenol (4-NP), as a typical nitro compound, can be used as an intermediate for pesticides, dyes and drugs. Due to its high water solubility and excellent chemical stability, 4-NP is easily enriched in organisms and can remain in the environment for a considerable period of time, causing serious ecological problems, posing a threat to human and animal health, and having carcinogenic effects. Therefore, how to effectively remove 4-NP from wastewater has received widespread attention.

[0003] To date, researchers have developed various traditional methods to improve the removal efficiency of 4-NP from wastewater, such as adsorption, photocatalytic degradation, and oxidative degradation. However, these methods typically have high investment costs, long operation times, and are susceptible to secondary contamination. In recent years, researchers have discovered that NaBH4 can effectively reduce 4-NP to the less toxic and biodegradable 4-aminophenol (4-AP). 4-AP is also a widely used industrial material, useful in the preparation of analgesic and antipyretic drugs, dyes, and antiseptic lubricants, making it commercially viable. Therefore, reducing 4-NP to 4-AP plays an important role in environmental protection and industrial applications. This method also offers advantages such as a simple operation process, mild reaction conditions, and complete conversion of 4-NP to 4-AP without the formation of byproducts. However, this reaction requires the addition of a catalyst. Therefore, the development of efficient catalysts that can be used to degrade 4-NP and generate 4-AP is of great significance. Summary of the Invention

[0004] The present invention provides a method for preparing a high-efficiency catalyst for degrading 4-NP and generating 4-AP: a method for preparing a porous cationic material with single-point anchoring of chloroplatinic acid anions.

[0005] The preparation method of the porous cationic material with single-point anchoring of chloroplatinic acid anions comprises the following steps:

[0006] S1: condensation reaction of pyrone with active methylene monomer Knoevenagel, cooling to room temperature, adding dropwise to ice water under vigorous stirring, and filtering to obtain pyranonitrile intermediate 1;

[0007] S2: Knoevenagel condensation reaction of the pyrancarbonitrile intermediate 1 and an aldehyde derivative, followed by filtration to obtain the pyrancarbonitrile intermediate 2;

[0008] S3: The pyranonitrile intermediate 2 and the oxidant FeCl3 are heated under reflux for reaction, filtered, and extracted with a Soxhlet extractor to obtain a porous material 1;

[0009] S4: The porous material 1 reacts with a quaternary ammonium salt to obtain a porous cationic material 2, and the porous cationic material 2 reacts with a platinum reagent to obtain the porous cationic material with a single-point anchoring of chloroplatinic acid anions.

[0010] Furthermore, the structural formula of the active methylene monomer is:

[0011]

[0012] The structural formula of the aldehyde monomer is:

[0013]

[0014] Furthermore, in step S1, the molar ratio of the pyrone to the active methylene monomer is 1:(1-2).

[0015] Furthermore, the condensation reaction conditions of the pyrone and the active methylene monomer Knoevenagel in step S1 are: acetic anhydride or dimethylformamide as solvent, reflux temperature controlled at 150-170° C., and reflux time 2-6 hours.

[0016] Furthermore, the Knoevenagel condensation reaction conditions of the pyranonitrile intermediate 1 and the aldehyde derivative in step S2 are: under an inert atmosphere, an inorganic base or piperidine as a catalyst, acetonitrile or ethanol as a solvent, and a reflux time of 24 to 48 hours at 60 to 120°C.

[0017] Furthermore, step S2 includes a drying process after filtration, and the drying conditions are vacuum drying at 60-120° C. for 1 day.

[0018] Furthermore, in step S3, the pyranonitrile intermediate 2 and the oxidant FeCl3 are heated under reflux under the following reaction conditions: under an inert atmosphere, the solvent is anhydrous dichloromethane or chloroform, and stirring is continued at 65-85° C. under condensation reflux for 48-72 hours.

[0019] Furthermore, the solvent in the Knoevenagel condensation reaction is selected from one or more of dimethyl sulfoxide, N,N-dimethylformamide, 1,4-dioxane, acetic anhydride, mesitylene, o-dichlorobenzene, acetonitrile, chloroform, 1,2-dichloroethane and n-butanol.

[0020] An object of the present invention is to provide a porous cationic material with single-point anchoring of chloroplatinic acid anions.

[0021] The porous cationic material with single-point anchoring of chloroplatinic acid anions is prepared by any of the preparation methods described above.

[0022] An object of the present invention is to provide a use of the porous cationic material with single-point anchored chloroplatinic acid anions as described above in the photocatalytic reduction of nitrophenol.

[0023] The preparation method of the porous cationic material with single-point anchored chloroplatinic acid anions provided by the present invention has mild reaction conditions and simple operation; the prepared porous cationic material with single-point anchored chloroplatinic acid anions has good thermal stability and excellent photocatalytic reduction ability; and the prepared porous cationic material with single-point anchored chloroplatinic acid anions has potential application prospects in treating p-nitrophenol wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of the preparation method of the porous cationic material with single-point anchoring of chloroplatinic acid anions provided by the present invention;

[0025] Figure 2 This is the thermogravimetric diagram of the porous cationic material with single-point anchoring of chloroplatinic acid anions in Example 1;

[0026] Figure 3 This is the N2 analysis-adsorption diagram of the porous cationic material with single-point anchoring of chloroplatinic acid anions in Example 1;

[0027] Figure 4 This is the XPS overall spectrum of the porous cationic material with single-point anchoring of chloroplatinic acid anions in Example 1;

[0028] Figure 5 This is a solid carbon spectrum of the porous cationic material with single-point anchoring of chloroplatinic acid anions in Example 1;

[0029] Figure 6 This is a Fourier transform infrared spectrum of the porous cationic material with single-point anchoring of chloroplatinic acid anions in Example 1;

[0030] Figure 7 is a SEM image of the porous cationic material with single-point anchoring of chloroplatinic acid anions in Example 1;

[0031] Figure 8 This is a curve showing the relationship between the photocatalytic reduction ability of the porous cationic material with single-point anchoring of chloroplatinic acid anions in Application Example 1 and the time of reduction of p-nitrophenol at the same concentration under conditions of different sodium borohydride concentrations;

[0032] Figure 9This is a curve showing the relationship between the photocatalytic reduction ability of the porous cationic material with single-point anchoring of chloroplatinic acid anions in Application Example 2 and the time of reduction of p-nitrophenol with different concentrations under the condition of the same concentration of sodium borohydride;

[0033] Figure 10 This is a curve showing the relationship between the photocatalytic reduction ability of the porous cationic material with single-point anchored chloroplatinic acid anions in Application Example 3 and the time of reduction of p-nitrophenol under the conditions of the same concentration of sodium borohydride and p-nitrophenol and different catalyst dosages. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but they should not be understood as limiting the scope of implementation of the present invention.

[0035] The present invention provides a method for preparing a porous cationic material (DCM-TPA-Pt) with single-point anchoring of chloroplatinic acid anions. The synthesis route is as follows:

[0036]

[0037] Refer to the instruction manual Figure 1 , including the following steps:

[0038] S1: condensation reaction of pyrone with active methylene monomer Knoevenagel, cooling to room temperature, adding dropwise to ice water under vigorous stirring, and filtering to obtain pyranonitrile intermediate 1;

[0039] S2: Knoevenagel condensation reaction of the pyrancarbonitrile intermediate 1 and an aldehyde derivative, followed by filtration to obtain the pyrancarbonitrile intermediate 2;

[0040] S3: The pyranonitrile intermediate 2 and the oxidant FeCl3 are heated under reflux for reaction, filtered, and extracted with a Soxhlet extractor to obtain a porous material 1;

[0041] S4: The porous material 1 reacts with a quaternary ammonium salt to obtain a porous cationic material 2, and the porous cationic material 2 reacts with a platinum reagent to obtain the porous cationic material with a single-point anchoring of chloroplatinic acid anions.

[0042] Example 1 is provided according to the preparation method of the above-mentioned porous cationic material (DCM-TPA-Pt) with single-point anchoring of chloroplatinic acid anions, and the porous cationic material with single-point anchoring of chloroplatinic acid anions prepared in Example 1 is used for the catalysis of p-nitrophenol in Application Examples 1-3.

[0043] Example 1

[0044] A method for preparing a porous cationic material with single-point anchoring of chloroplatinic acid anions comprises the following steps:

[0045] Step 1: Add 2,6-dimethyl-4H-pyran-4-one (2.0 g, 16 mmol), malononitrile (2.0 g, 30 mmol), and acetic anhydride to a reaction vessel, mix thoroughly, and heat to 160°C under reflux for 2 hours. After completion, the reaction mixture was cooled to room temperature and added dropwise to ice water with vigorous stirring. The mixture was filtered and dried under vacuum for 1 day to obtain 2.70 g of a brown powder, Compound 1. Yield: 98%.

[0046] Step 2: Compound 1 (1.0 g) and 4-diphenylaminobenzaldehyde (3.0 g, 11 mmol) were added to a reactor. Under a nitrogen atmosphere, acetonitrile and piperidine were added and mixed thoroughly. The reaction was refluxed at 100°C for 24 hours and monitored by TLC. After completion of the reaction, the mixture was filtered and vacuum dried for 1 day to obtain 3.49 g of compound 2 as a red powder. Yield: 85.3%.

[0047] Step 3: Compound 2 (0.682 g, 1 mmol) obtained in Step 2 and 30 mL of anhydrous dichloromethane were added to the reactor. Under a nitrogen atmosphere, the oxidant FeCl3 was added and mixed thoroughly. The mixture was heated to 65°C and stirred under reflux for 48 hours. After completion of the reaction, the crude product was filtered. Finally, the product was extracted with THF and dried under vacuum for 1 day to obtain 574 mg of the red product 1 (DCM-TPA).

[0048] Step 4: POP-TPA (1.0 g, 1.46 mmol) obtained in step 3 was added to a reaction vessel, and 2-bromoethyltrimethylammonium bromide was added. After mixing well, the mixture was reacted to obtain a porous cationic material 2 (DCM-TPA-Br);

[0049] Step 5: Add the DCM-TPA-Br obtained in step 4 to a reaction vessel, add potassium hexachloroplatinate, mix well, and react to obtain the final porous cationic material 3 (DCM-TPA-Pt) with single-point anchoring of chloroplatinic acid anions;

[0050] Step 6: The porous cationic material with single-point anchored chloroplatinic acid anions obtained in step 5 is applied to the photocatalytic reduction of p-nitrophenol.

[0051] The specific surface area of ​​the cationic porous organic material with single-point anchoring of chloroplatinic acid anions prepared in Example 1 is 393.8977 m 2 ·g -1 At the same time, the performance of the cationic porous organic material with single-point anchoring of chloroplatinic acid anions was tested, see the instructions. Figure 2-7 . Figure 2The thermogravimetric analysis of the cationic porous material shows that when the temperature reaches 281°C, the weight loss of the material is only 10%, indicating that the material has good thermal stability and is not easily decomposed at high temperatures. Figure 3 is the nitrogen adsorption-desorption curve of DCM-TPA-Pt, from Figure 3 The analysis showed that the specific surface area of ​​DCM-TPA-Pt reached 393.8977m 2 g -1 , a uniform and appropriate specific surface area is conducive to the photocatalytic reduction reaction. Figure 4-6 The DCM-TPA-Pt was characterized by XPS, solid carbon spectrum and infrared. Figure 4 It can be seen that the distribution of various elements and the presence of metal Pt. Figure 5-6 The characterization results illustrate the presence of various functional groups of DCM-TPA-Pt, indicating the successful synthesis of the polymer.

[0052] Application Example 1

[0053] Photocatalytic reduction experiments of different concentrations of NaBH4:

[0054] The cationic porous organic material with single-point anchoring of chloroplatinic acid anions obtained in Example 1 was subjected to photocatalytic reduction studies with different concentrations of NaBH4 (sodium borohydride);

[0055] Test sample: the porous cationic material with single-point anchoring of chloroplatinic acid anions (DCM-POP-Pt) obtained in Example 1;

[0056] Preparation of sodium borohydride solution: prepare sodium borohydride solution with initial concentrations of 0.5M / 1M / 2M respectively;

[0057] Experimental method: 30 mg of DCM-TPA-Pt was dispersed in 5 mL of sodium borohydride aqueous solution and sonicated for 2 minutes. The solution was then transferred to a photocatalytic reactor and stirred at 800 rpm. 25 mL of a 10 ppm p-nitrophenol solution was added while turning on a xenon lamp. 2 mL of the mixture was removed at regular intervals using a syringe and immediately passed through a 0.22 μm syringe filter. The concentration of the filtrate was measured using a UV-visible spectrometer. Sodium borohydride solution and sodium borohydride solution + nitrophenol solution were used as controls.

[0058] Figure 8 The following plots show the photocatalytic reduction ability of the porous cationic material with single-point anchoring of chloroplatinic acid anions obtained in Application Example 1, which was used to reduce 10 ppm of p-nitrophenol in the presence of different sodium borohydride concentrations. (a) 0.5 M sodium borohydride solution; (b) 1 M sodium borohydride solution; (c) 2 M sodium borohydride solution.

[0059] When the concentration of sodium borohydride solution is constant, the absorbance gradually decreases with time, indicating that the conversion rate of p-nitrophenol increases. At the same time point, under the conditions of different sodium borohydride solution concentrations, the absorbance increases with the increase of sodium borohydride solution concentration, indicating that the conversion rate of p-nitrophenol increases.

[0060] Application Example 2

[0061] Photocatalytic reduction experiments of 4-NP at different concentrations:

[0062] The cationic porous organic material with single-point anchored chloroplatinic acid anions obtained in Example 1 was subjected to photocatalytic reduction studies of 4-NP at different concentrations;

[0063] Test sample: cationic porous organic material with single-point anchoring of chloroplatinic acid anions (DCM-POP-Pt) obtained in Example;

[0064] Preparation of p-nitrophenol solution: prepare p-nitrophenol solution with initial concentration of 10ppm / 20ppm / 50ppm respectively;

[0065] Experimental method: 30 mg of DCM-TPA-Pt was dispersed in 5 mL of 1 M sodium borohydride aqueous solution and pre-ultrasonicated for 2 minutes. The solution was then transferred to a photocatalytic reactor and stirred at 800 rpm. 25 mL of p-nitrophenol solution was added while turning on the xenon lamp. 2 mL of the mixture was removed at regular intervals using a syringe and immediately passed through a 0.22 μm syringe filter. The concentration of the filtrate was measured using a UV-visible spectrometer. Sodium borohydride solution and sodium borohydride solution + nitrophenol solution were used as controls.

[0066] Figure 9 The following graphs show the time-dependent photocatalytic reduction activity of the cationic porous organic material with single-point anchoring of chloroplatinic acid anions obtained in Example 2 for reducing p-nitrophenol solutions of varying concentrations. (a) 10 ppm nitrophenol solution; (b) 20 ppm nitrophenol solution; (c) 50 ppm nitrophenol solution.

[0067] Under the condition of constant p-nitrophenol concentration, the absorbance decreases over time, indicating that the p-nitrophenol conversion rate increases. At the same time point, under the condition of different p-nitrophenol concentrations, the absorbance decreases as the concentration of p-nitrophenol increases, indicating that the p-nitrophenol solution with a concentration of 10 ppm has the highest conversion rate, the p-nitrophenol solution with a concentration of 20 ppm has the second highest conversion rate, and the p-nitrophenol solution with a concentration of 50 ppm has the lowest conversion rate.

[0068] Application Example 3

[0069] Different concentrations of catalyst

[0070] The cationic porous organic material with single-point anchoring of chloroplatinic acid anions obtained in the example was subjected to photocatalytic reduction studies with different catalyst concentrations;

[0071] Test sample: cationic porous organic material with single-point anchoring of chloroplatinic acid anions (DCM-POP-Pt) obtained in Example;

[0072] Preparation of catalysts with different concentrations: cationic porous organic material catalysts with single-point anchored chloroplatinic acid anions were prepared with starting concentrations of 0.5 / 1 / 2 mg / mL;

[0073] Experimental method: 30 mg of DCM-TPA-Pt was dispersed in 5 mL of 1 M sodium borohydride aqueous solution and pre-ultrasonicated for 2 minutes. It was then transferred to a photocatalytic reactor and stirred at 800 rpm. 25 mL of 10 ppm p-nitrophenol solution was added while turning on the xenon lamp. 2 mL of the mixture was removed at regular intervals using a syringe and immediately passed through a 0.22 μm syringe filter. The concentration of the filtrate was measured using a UV-visible spectrometer. Sodium borohydride solution and sodium borohydride solution + nitrophenol solution were used as controls.

[0074] Figure 10 The following curves show the time-dependent photocatalytic reduction ability of the cationic porous organic material obtained in Application Example 3 for the reduction of 10 ppm of p-nitrophenol. (a) 0.5 mg / mL of a single-point-anchored chloroplatinic acid anion cationic porous organic material catalyst; (b) 1 mg / mL of a single-point-anchored chloroplatinic acid anion cationic porous organic material catalyst; (c) 2 mg / mL of a single-point-anchored chloroplatinic acid anion cationic porous organic material catalyst.

[0075] When the catalyst concentration was increased from 0.5 mg / mL to 1 mg / mL, the absorbances of the two were compared at 1, 2, and 3 minutes, respectively. The absorbance became smaller, indicating that the conversion rate of p-nitrophenol increased with increasing concentration. However, when the catalyst concentration was increased from 1 mg / mL to 2 mg / mL, the absorbances of the two were compared at 1, 2, and 3 minutes, respectively. The absorbance became larger, indicating that the conversion rate of p-nitrophenol decreased with higher concentration. The comparison shows that when the catalyst concentration is too high, its promoting effect on the photocatalytic reduction reaction decreases.

Claims

1. A method for preparing a porous cationic material with single-point anchoring of chloroplatinic acid anions, characterized in that: The following steps are involved: S1: condensation reaction of pyrone with active methylene monomer Knoevenagel, cooling to room temperature, adding dropwise to ice water under vigorous stirring, and filtering to obtain pyranonitrile intermediate 1; S2: condensing the pyrancarbonitrile intermediate 1 with an aldehyde monomer Knoevenagel, followed by filtration to obtain a pyrancarbonitrile intermediate 2; S3: The pyranonitrile intermediate 2 and the oxidant FeCl3 are heated under reflux for reaction, filtered, and extracted with a Soxhlet extractor to obtain a porous material 1; S4: the porous material 1 reacts with a quaternary ammonium salt to obtain a porous cationic material 2, and the porous cationic material 2 reacts with a platinum reagent to obtain the porous cationic material with a single-point anchoring of chloroplatinic acid anions; The structural formula of the pyrone is: The structural formula of the active methylene monomer is: ， The structural formula of the aldehyde monomer is: ； The platinum reagent is potassium hexachloroplatinate.

2. The method for preparing a porous cationic material with single-point anchoring of chloroplatinic acid anions according to claim 1, wherein: In step S1, the molar ratio of the pyrone to the active methylene monomer is 1:(1-2).

3. The method for preparing a porous cationic material with single-point anchoring of chloroplatinic acid anions according to claim 1, wherein: The condensation reaction conditions of the pyrone and the active methylene monomer Knoevenagel in step S1 are: acetic anhydride or dimethylformamide as solvent, reflux temperature controlled at 150-170° C., and reflux time 2-6 hours.

4. The method for preparing a porous cationic material with single-point anchoring of chloroplatinic acid anions according to claim 1, wherein: The Knoevenagel condensation reaction conditions of the pyranonitrile intermediate 1 and the aldehyde monomer in step S2 are: in an inert atmosphere, an inorganic base or piperidine as a catalyst, acetonitrile or ethanol as a solvent, and a reflux time of 24 to 48 hours at 60 to 120°C.

5. The method for preparing a porous cationic material with single-point anchoring of chloroplatinic acid anions according to claim 1, wherein: Step S2 includes a drying process after filtration, and the drying conditions are vacuum drying at 60-120° C. for 1 day.

6. The method for preparing a porous cationic material with single-point anchoring of chloroplatinic acid anions according to claim 1, wherein: The pyranonitrile intermediate 2 and the oxidant FeCl3 in step S3 are heated under reflux under inert atmosphere, the solvent is anhydrous dichloromethane or chloroform, and stirring is continued at 65-85°C under condensation reflux for 48-72 hours.

7. The method for preparing a porous cationic material with single-point anchoring of chloroplatinic acid anions according to claim 1, wherein: The solvent in the Knoevenagel condensation reaction is selected from dimethyl sulfoxide, N , N - one or more of dimethylformamide, 1,4-dioxane, acetic anhydride, mesitylene, o-dichlorobenzene, acetonitrile, chloroform, 1,2-dichloroethane and n-butanol.

8. A porous cationic material with single-point anchoring of chloroplatinic acid anions, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the porous cationic material with single-point anchoring of chloroplatinic acid anions as claimed in claim 8 in the photocatalytic reduction of nitrophenol.

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