Iron-based MOF / PAN composite material and preparation method and application thereof

Abstract

The application belongs to the technical field of adsorbing materials, and particularly relates to a kind of iron-based MOF / PAN composite material and its preparation method and application, the composite material takes PAN as carrier, and MOF is loaded on the carrier PAN, including two steps of preparing polyformaldehyde amine (PAN) and compounding PAN with MOF, the steps include: a. monomer melamine, 4-carboxyl benzaldehyde is dissolved into dimethyl sulfoxide, then heated under nitrogen atmosphere, after the reaction is completed, polyformaldehyde amine is obtained after purification treatment; b. after mixing polyformaldehyde amine with iron-based MOF precursor, put into high-pressure reaction kettle for solvothermal reaction, then obtain iron-based MOF / PAN composite material after purification treatment. The MOF / PAN composite material provided by the application has good adsorption performance on benzene and benzene pollutants.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of adsorption materials, and particularly relates to an iron-based MOF / PAN composite material and a preparation method and application thereof. BACKGROUND

[0002] Benzene is a basic raw material for petroleum chemical industry, which is a colorless, transparent liquid with sweet taste at room temperature, has a density less than water, and has a strong aromatic odor. If long-term contact with high-concentration benzene series, it will cause serious damage to the nervous system and blood system. The World Health Organization also lists benzene as a carcinogenic list, therefore, the environmental governance of benzene pollutants is of great significance.

[0003] For the removal of benzene pollutants, the most commonly used method is adsorption, and the key to adsorption is the selection of adsorbent. MOF materials have a high position in gas adsorption and storage due to their high specific surface area, large pore volume, adjustable structure and function, etc. However, even if MOF has a high adsorption capacity, its adsorption of benzene pollutants is still limited, and part of the benzene molecules can only be adsorbed on the surface of the pore, and cannot enter the MOF pore in large quantities. After the MOF is compounded with polyoxymethylene amine for a suitable pore size, more adsorption forces are provided, which can greatly improve the adsorption capacity.

[0004] Chinese patents CN113145084A and CN115090273A prepared MIL-101 / PDVB composite material and MIL-101 / NPAN composite material for adsorbing benzene gas by one-step hydrothermal process. In order to improve the crystallinity of the material, NaOH, HF, HCL and other acid-base mineralizers are added during preparation, and the synthesis temperature is 160-180℃. Secondly, Cr(NO3)3·9H2O is used in the preparation of MOF material. Cr is a heavy metal with high toxicity, which has cumulative and biological chain concentration characteristics, can migrate to the soil in the form of ions, and accumulate in various organisms. Excessive intake can harm the human body. SUMMARY

[0005] One of the purposes of the present application is to provide a MOF / PAN composite material for adsorbing benzene gas, which is prepared by using polyoxymethylene amine (PAN) as a carrier, MOF as a component and dispersing on the surface of PAN. The MOF / PAN composite material has high specific surface area, large pore volume of MOF and rich benzene functional groups of PAN, and the π-π conjugation effect increases the adsorption capacity of benzene gas.

[0006] The mass content of PAN in the MOF / PAN composite material is 3.8 wt% to 5.7 wt%, preferably 4.7 wt% to 5.2 wt%, and more preferably 5.2 wt%.

[0007] The second object of the present application is to provide the preparation method of the MOF / PAN composite material for benzene gas adsorption, using PAN as the carrier, adding the MOF precursor solution to uniformly mix to obtain the MOF / PAN precursor solution, and then preparing by the solvothermal method; specifically including the following steps:

[0008] a. Dissolving the monomers melamine and 4-carboxybenzaldehyde into dimethyl sulfoxide, heating to 170-180°C and keeping in N2 atmosphere for 72-80 h, then separating, drying and grinding to prepare the PAN;

[0009] b. Mixing the iron chloride hexahydrate, terephthalic acid and N,N-dimethylformamide in a molar ratio of 2:1:233-236 uniformly to obtain the MOF precursor solution, then adding the PAN powder prepared in step a, and ultrasonic mixing at room temperature to obtain the MOF / PAN precursor solution;

[0010] c. Pouring the MOF / PAN precursor solution into a polytetrafluoroethylene high-pressure reaction kettle and placing it in an oven for solvothermal reaction to obtain the unpurified MOF / PAN composite material;

[0011] d. Adding the obtained unpurified MOF / PAN composite material into N,N-dimethylformamide and hot ethanol for purification to obtain the purified MOF / PAN composite material;

[0012] e. Washing and drying the above-mentioned purified MOF / PAN composite material with distilled water and ethanol to obtain the MOF / PAN composite material for benzene gas adsorption.

[0013] Further, the molar ratio of melamine to 4-carboxybenzaldehyde is 2:3.

[0014] Further, the solvothermal reaction temperature is 110-130°C, and the reaction time is 22-24 h.

[0015] Further, the drying is at 115-120°C for 6-8 h.

[0016] The present application also provides the application of the above-mentioned iron-based MOF / PAN composite material, which is used for adsorbing benzene gas; the benzene gas includes benzene, toluene and o-xylene.

[0017] Compared with the prior art, the present application has the following advantages:

[0018] 1. The present application can greatly improve the adsorption capacity of MOF for benzene by only compounding polyformaldehyde amine, providing more ideas for MOF composite materials;

[0019] 2. The present application uses Fe3+ Replaced Cr 3+ The use of the solvothermal method to synthesize MOFs not only reduces costs but also reduces environmental pollution, making them environmentally friendly materials.

[0020] 3. This invention uses a solvothermal method instead of a hydrothermal method to prepare composite materials. The synthesis temperature is 110-130℃. The crystallinity of the material can be improved without the use of mineralizers, which reduces the process cost and raw material cost. Attached Figure Description

[0021] Figure 1 The XRD diffraction patterns of the MOF / PAN composite material prepared in Example 3 and the MOF material prepared in Comparative Example 1 are shown.

[0022] Figure 2 The images shown are SEM images of the MOF / PAN composite material prepared in Example 3 and the MOF material prepared in Comparative Example 1.

[0023] Figure 3 The N2 adsorption-desorption curves of the MOF / PAN composite material prepared in Example 3 and the MOF material prepared in Comparative Example 1 are shown.

[0024] Figure 4 The static benzene gas adsorption curves of the MOF / PAN composite material prepared in Example 3 and the MOF / PAN prepared in Comparative Example 1 are shown. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to examples:

[0026] Examples 1 to 4 are preferred embodiments based on the technical solution of the present invention, but are not limited thereto. Example 1

[0027] a. Dissolve 0.4 g of melamine and 0.72 g of 4-carboxybenzaldehyde in 25 mL of dimethyl sulfoxide, heat to 180 °C and maintain in N2 atmosphere for 72 h, wash with N,N-dimethylformamide, acetone and dichloromethane respectively, vacuum dry and grind to obtain the PAN;

[0028] b. Mix 0.675 g FeCl3·6H2O, 0.208 g terephthalic acid, and 22.5 mL N,N-dimethylformamide (0.2918 mol) evenly to obtain the MOF precursor solution, and then add 0.035 g of PAN powder obtained in step a (the mass content of PAN and the MOF / PAN composite material used for adsorbing benzene gases is 3.8 wt%).

[0029] c. Pour the MOF / PAN precursor solution into a polytetrafluoroethylene high-pressure reaction kettle, place it in an oven at 130°C for 24 h, and obtain an unpurified MOF / PAN composite material;

[0030] d. Add the obtained unpurified MOF / PAN composite material to N,N-dimethylformamide and 70°C hot ethanol for purification, and obtain a purified MOF / PAN composite material;

[0031] e. Dry the above purified MOF / PAN composite material at 120°C for 6 h and grind it, and the MOF / PAN composite material for benzene gas adsorption is obtained.

[0032] The MOF / PAN composite material for benzene gas adsorption prepared in this example is measured for the adsorption amount of benzene gas under the conditions of ambient temperature 25°C, initial concentration of benzene gas 3 g / L, and adsorption time 24 h, and the adsorption amount is measured to be 1830 mg / g by using the static desiccator method. Example 2

[0033] a. Dissolve 0.4 g of melamine and 0.72 g of 4-carboxybenzaldehyde in 25 mL of dimethyl sulfoxide, heat to 180°C and keep in an N2 atmosphere for 72 h, and after washing with N,N-dimethylformamide, acetone and dichloromethane, vacuum dry and grind to obtain the PAN;

[0034] b. Mix 0.675 g of FeCl3·6H2O and 0.208 g of terephthalic acid uniformly with 22.5 mL of N,N-dimethylformamide to obtain the MOF precursor solution, and then add 0.044 g of the PAN powder prepared in step a (the mass content of PAN in the MOF / PAN composite material for adsorbing benzene gas is 4.7 wt%);

[0035] c. Pour the MOF / PAN precursor solution into a polytetrafluoroethylene high-pressure reaction kettle, place it in an oven at 130°C for 24 h, and obtain an unpurified MOF / PAN composite material;

[0036] d. Add the obtained unpurified MOF / PAN composite material to N,N-dimethylformamide and 70°C hot ethanol for purification, and obtain a purified MOF / PAN composite material;

[0037] e. Dry the above purified MOF / PAN composite material at 120°C for 6 h and grind it, and the MOF / PAN composite material for benzene gas adsorption is obtained.

[0038] The MOF / PAN composite material for benzene gas adsorption prepared in this example was measured for benzene gas adsorption capacity under the conditions of ambient temperature 25℃, initial benzene gas concentration 3 g / L, and adsorption time 24 h, and the adsorption capacity was 1997 mg / g. Example 3

[0039] a. 0.4 g of melamine, 0.72 g of 4-carboxybenzaldehyde were dissolved in 25 mL of dimethyl sulfoxide, heated to 180℃ and kept in N2atmosphere for 72 h, washed with N,N-dimethylformamide, acetone, dichloromethane respectively, vacuum dried and ground to obtain the PAN;

[0040] b. 0.675 g of FeCl3·6H2O, 0.208 g of terephthalic acid, 22.5 mL of N,N-dimethylformamide were mixed uniformly to obtain the MOF precursor solution, and then 0.048 g of the PAN prepared in step a (the mass content of PAN in the MOF / PAN composite material for adsorbing benzene gas was 5.2 wt%) was added;

[0041] c. The MOF / PAN precursor solution was poured into a polytetrafluoroethylene high-pressure reaction kettle, which was placed in an oven at 130℃ for 24 h to obtain the unpurified MOF / PAN composite material;

[0042] d. The obtained unpurified MOF / PAN composite material was added to N,N-dimethylformamide and hot ethanol at 70℃ for purification to obtain the purified MOF / PAN composite material;

[0043] e. The purified MOF / PAN composite material was dried at 120℃ for 6 h and ground to obtain the MOF / PAN composite material for benzene gas adsorption.

[0044] The MOF / PAN composite material for benzene gas adsorption prepared in this example was measured for benzene gas adsorption capacity under the conditions of ambient temperature 25℃, initial benzene gas concentration 3 g / L, and adsorption time 24 h, and the adsorption capacity was 2341 mg / g. Example 4

[0045] a. 0.4 g of melamine, 0.72 g of 4-carboxybenzaldehyde were dissolved in 25 mL of dimethyl sulfoxide, heated to 180℃ and kept in N2atmosphere for 72 h, washed with N,N-dimethylformamide, acetone, dichloromethane respectively, vacuum dried and ground to obtain the PAN;

[0046] b. 0.675 g FeCl3·6H2O, 0.208 g terephthalic acid, 22.5 mL N,N- dimethylformamide were mixed uniformly to obtain the MOF precursor solution, and then 0.052 g of the PAN powder prepared in step a (the mass content of PAN in the MOF / PAN composite for adsorbing benzene gas was 5.7 wt%) was added;

[0047] c. The MOF / PAN precursor solution was poured into a polytetrafluoroethylene high-pressure reaction kettle, and placed in an oven at 130°C for 24 h to obtain an unpurified MOF / PAN composite;

[0048] d. The obtained unpurified MOF / PAN composite was added to N,N- dimethylformamide and 70°C hot ethanol for purification to obtain a purified MOF / PAN composite;

[0049] e. The above purified MOF / PAN composite was dried at 120°C for 6 h and ground to obtain the MOF / PAN composite for adsorbing benzene gas.

[0050] The MOF / PAN composite for adsorbing benzene gas prepared in this example was measured for adsorption capacity of benzene gas under the conditions of ambient temperature 25°C, initial concentration of benzene gas 3 g / L, and adsorption time 24 h, and the adsorption capacity was measured to be 1839 mg / g. Comparative Example 1

[0051] The MOF was prepared according to the following method

[0052] a. 0.675 g FeCl3·6H2O, 0.208 g terephthalic acid, 22.5 mL N,N- dimethylformamide were mixed uniformly to obtain the MOF precursor solution, and then 0.052 g of the PAN powder prepared in step a (the mass content of PAN in the MOF / PAN composite for adsorbing benzene gas was 5.7 wt%) was added;

[0053] b. The MOF precursor solution was poured into a polytetrafluoroethylene high-pressure reaction kettle, and placed in an oven at 130°C for 24 h to obtain an unpurified MOF / PAN composite;

[0054] c. The unpurified MOF was added to a certain amount of N,N- dimethylformamide and 70°C hot ethanol for purification;

[0055] d. The purified product was washed with distilled water and ethanol, and dried to obtain the MOF.

[0056] d. The purified product was washed with distilled water and ethanol, and dried to obtain the MOF.

[0057] The MOF prepared in the present example for benzene gas adsorption was measured for benzene gas adsorption capacity using a static desiccator method under the conditions of ambient temperature 25℃, initial benzene gas concentration 3 g / L, and adsorption time 24 h, and the adsorption capacity was measured to be 918 mg / g.

[0058] Figure 1 The XRD diffraction spectra of the MOF material prepared in Comparative Example 1 and the MOF / PAN composite material prepared in Example 3 are shown. It can be seen that the characteristic diffraction peaks of the MOF and the MOF / PAN composite material are consistent, and the characteristic peak intensity of the composite material is weakened. Figure 1 It can be seen that the characteristic diffraction peaks of the MOF and the MOF / PAN composite material are consistent, and the characteristic peak intensity of the composite material is weakened.

[0059] Figure 2 The SEM photos of the MOF material prepared in Comparative Example 1 (a) and the MOF / PAN composite material prepared in Example 3 (b) are shown. It can be seen that the MOF has been successfully loaded onto the surface of the PAN. Figure 2 It can be seen that the MOF has been successfully loaded onto the surface of the PAN.

[0060] Figure 3 The N2 adsorption-desorption curves of the MOF material prepared in Comparative Example 1 and the MOF / PAN composite material prepared in Example 3 are shown.

[0061] Figure 4 The static benzene gas adsorption curves of the MOF / PAN composite material prepared in Comparative Example 1 and the MOF / PAN composite material prepared in Example 3 are shown.

Claims

1. An iron-based MOF / PAN composite material, characterized in that, The mass content of polyacetalamine in the iron-based MOF / PAN composite material is 3.8 wt%~5.7 wt%; The polyacetalamine is prepared by the following method: melamine monomers and 4-carboxybenzaldehyde are dissolved in dimethyl sulfoxide, heated to 170-180°C and maintained in a N2 atmosphere for 72-80 hours, and then separated, dried and ground to obtain the polyacetalamine; wherein the molar ratio of melamine to 4-carboxybenzaldehyde is 2:

3. The preparation method of the iron-based MOF / PAN composite material is as follows: using polyacetalamine as a carrier, an iron-based MOF precursor solution is added and uniformly mixed to obtain an iron-based MOF / PAN precursor solution; the iron-based MOF / PAN precursor solution is subjected to a solvothermal reaction at 110~130℃ for 22~24h to obtain the iron-based MOF / PAN composite material; the iron-based MOF precursor solution includes ferric chloride hexahydrate, terephthalic acid, and N,N-dimethylformamide in a molar ratio of 2:1:233~236.

2. A method for preparing the iron-based MOF / PAN composite material as described in claim 1, characterized in that, The preparation method is as follows: using the polyacetalamine described in claim 1 as a carrier, an iron-based MOF precursor solution is added and mixed uniformly to obtain an iron-based MOF / PAN precursor solution; the iron-based MOF / PAN precursor solution is subjected to a solvothermal reaction to obtain the iron-based MOF / PAN composite material.

3. The method for preparing the iron-based MOF / PAN composite material according to claim 2, characterized in that, The iron-based MOF precursor solution comprises ferric chloride hexahydrate, terephthalic acid, and N,N-dimethylformamide in a molar ratio of 2:1:233~236.

4. The method for preparing the iron-based MOF / PAN composite material according to claim 2, characterized in that, The temperature of the solvothermal reaction is 110~130℃, and the reaction time is 22~24h.

5. The method for preparing the iron-based MOF / PAN composite material according to claim 2, characterized in that, The preparation method also includes purifying, washing, and drying the iron-based MOF / PAN composite material.

6. The method for preparing the iron-based MOF / PAN composite material according to claim 5, characterized in that, The purification process involved adding N,N-dimethylformamide and hot ethanol to the iron-based MOF / PAN composite material for purification.

7. The method for preparing the iron-based MOF / PAN composite material according to claim 5, characterized in that, The drying process involves drying at 115-120℃ for 6-8 hours.

8. An application of the iron-based MOF / PAN composite material as described in claim 1, characterized in that, The iron-based MOF / PAN composite material is used to adsorb benzene-like gases.

9. The application of the iron-based MOF / PAN composite material according to claim 8, characterized in that, The benzene-based gases include benzene, toluene, and o-xylene.

Images