Porous organic polymer rich in carboxylic acid groups as well as preparation method and application of porous organic polymer

Abstract

The invention discloses a porous organic polymer rich in carboxylic acid groups and a preparation method and application thereof, and belongs to the technical field of polymer materials.The preparation method of the porous organic polymer rich in carboxylic acid groups comprises the following steps that an aromatic compound is used as a substrate, aluminum chloride is used as an activating agent, and the organic polymer rich in carboxylic acid groups is obtained; the method comprises the following steps: adding an aromatic compound and aluminum chloride into dichloromethane, and carrying out constant-temperature reaction to obtain a reaction solution; and filtering the reaction liquid, washing the obtained solid, and carrying out thermal oxidation treatment at the temperature of 150-250 DEG C to obtain the porous organic polymer rich in carboxylic acid groups. The preparation method has the advantages of cheap and easily available raw materials, simple preparation process and wide applicability, and the prepared porous organic polymer rich in carboxylic acid groups has excellent ammonia gas adsorption performance.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to a porous organic polymer rich in carboxylic acid groups, a preparation method and application thereof. Background Art

[0002] Ammonia (NH3) is one of the most produced chemicals each year and is widely used in agriculture, industry and the military. However, the widespread use of ammonia also brings inevitable leakage problems. Even a small amount of leakage can have serious impacts on the environment and health. Ammonia is toxic and corrosive. Direct contact can cause irritation to the eyes, skin and respiratory system. In addition, ammonia reacts with nitrogen oxides and sulfur oxides (NO x and SO x ) reacts to form fine particulate matter (PM2.5), which can cause serious health problems. Therefore, strict control of ammonia is crucial.

[0003] Ammonia has the advantages of being easily liquefied (-33°C), having a high volumetric energy density (the volumetric energy of liquid ammonia is 50% higher than that of liquid hydrogen), having transport and storage facilities that are compatible with propane, having low manufacturing costs, and being a carbon-free fuel. In addition to being decomposed into hydrogen, ammonia can also be directly burned in large gas turbines. This highly efficient combustion process produces no CO2, making it one of the current research hotspots in large-scale power generation. Ammonia is currently considered a potential alternative to hydrogen energy. However, ammonia is highly corrosive and toxic, and its storage materials need to be resistant to the irreversible poisoning of active sites by NH3 molecules.

[0004] Traditional solid adsorbents for ammonia, such as polymer resins, silica gel, alumina, zeolites, and carbonaceous materials, work under mild conditions, but due to the low selectivity of single-material adsorbents for ammonia, methods for selectively binding ammonia have been studied. Since activated carbon binds ammonia primarily through weak attractive forces, further oxidation or impregnation of the carbon material with metal chlorides or metal oxides has been studied to provide additional forces. Although surface modification aids adsorption to some extent, complex designs are limited by the inherent irregular pore size and amorphous network functionality. Similarly, acid functionalization on zeolites has not significantly increased the adsorption capacity, material regeneration is also difficult, and the structure of the zeolite is prone to collapse as the pore size increases.

[0005] In this context, porous materials such as metal organic frameworks, covalent organic frameworks, hydrogen bonded organic frameworks and porous organic polymers have become a research hotspot for the new generation of ammonia adsorbents due to their high porosity, adjustable functions and structural diversity. The high surface area, diverse topological structures and diverse pore structures of new porous materials contribute to their diverse applications, such as gas storage and separation, catalysis, magnetism, proton conduction and chemical sensing. The specific properties required for the intended application can be obtained by changing the composition or post-synthesis modification. For example, since ammonia acts as both a Lewis base and Bases, acidic sites on porous materials can enhance their capture at low concentrations. These acidic sites can be achieved by: removing solvent molecules on the nodes of metal-organic frameworks to produce open metal sites with high Lewis acidity; incorporating acidic functional groups (such as carboxylic acid, phosphoric acid and sulfonic acid groups) into porous organic polymers; or introducing metal ions into porous materials. In addition, composite materials made by mixing porous materials with other materials such as polymers or activated carbon have recently become one of the excellent alternatives for developing effective materials. This approach is very attractive because it can easily make up for the shortcomings of each material, thereby achieving better performance.

[0006] Research has shown that ammonia adsorption depends on the interplay between active site density, the strength of the adsorbent-adsorbate interaction, pore size, and effective surface area. Excellent ammonia adsorption and storage materials should possess high adsorption capacity, good reversibility, and structural stability. Although metal-organic frameworks (MOFs) have demonstrated excellent performance in ammonia adsorption, they still face challenges in structural stability, regeneration, and cost control. For example, some MOFs are susceptible to structural degradation under humid conditions, especially in high-ammonia environments. Furthermore, MOF regeneration conditions (such as high-temperature desorption) may affect their long-term performance. Porous organic polymers composed of strong C-C bonds offer the advantages of high structural stability and reusability for ammonia capture, but their ammonia adsorption capacity is modest. The adsorption performance of porous organic polymers can be enhanced by designing and synthesizing porous organic polymers with functional groups, such as acidic groups. Their synthesis generally involves two methods: polymerization using monomers bearing functional groups and post-modification of the porous organic polymer. The former limits the monomers available and is more expensive. The latter requires sufficient internal space in the porous material and good chemical stability of the framework. Therefore, it is very necessary to provide a method for obtaining porous polymers with a large number of functional groups using simple substrate reactions, which will simplify the synthesis process and significantly reduce costs. Summary of the Invention

[0007] The object of the present invention is to provide a method for preparing a porous organic polymer rich in carboxylic acid groups, so as to solve the problems raised in the above background technology.

[0008] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0009] A method for preparing a porous organic polymer rich in carboxylic acid groups comprises the following steps:

[0010] The aromatic compound is used as a substrate and aluminum chloride is used as an activator. The aromatic compound and aluminum chloride are added to dichloromethane for constant temperature reaction to obtain a reaction solution; dichloromethane is used as a cross-linking agent and solvent;

[0011] The reaction solution is filtered, the obtained solid is washed, and then subjected to thermal oxidation treatment at a temperature of 150-250° C. to obtain the porous organic polymer rich in carboxylic acid groups.

[0012] Preferably, the mass ratio of the aromatic compound to aluminum chloride is 1:(2.5-5.5).

[0013] Preferably, the temperature of the isothermal reaction is 50-120°C.

[0014] Preferably, the environment for the thermal oxidation treatment is an air atmosphere.

[0015] Preferably, the thermal oxidation treatment time is 0.5-48 hours. The temperature and heating time of the thermal oxidation treatment should be appropriate to obtain the optimal carboxylic acid content while avoiding polymer degradation.

[0016] Preferably, the aromatic compound is any one of biphenyl, benzene, 1,3,5-triphenylbenzene, naphthalene, p-terphenyl, mesitylene, toluene and anthracene.

[0017] Another object of the present invention is to provide a porous organic polymer rich in carboxylic acid groups prepared by the above preparation method.

[0018] Preferably, the carboxyl content of the porous organic polymer rich in carboxylic acid groups is 2-8 mmol / g, and the specific surface area is 1-500 m 2 / g.

[0019] Another object of the present invention is to provide an application of the above-mentioned porous organic polymer rich in carboxylic acid groups in the adsorption separation of ammonia. At 298K and 1 bar, the adsorption capacity of ammonia by the porous organic polymer rich in carboxylic acid groups can reach 15-20 mmol / g.

[0020] The preparation method provided by the present invention uses cheap and readily available raw materials (all of which are bulk commodities with low cost), has a simple preparation process, does not require any expensive oxidants and Lewis acid catalysts, and only uses air thermal oxidation, thus having wide applicability. The preparation method is controllable on the product, and the specific surface area and carboxyl content of the product can be adjusted. The prepared porous organic polymer rich in carboxylic acid groups has a high carboxylic acid group content and excellent ammonia adsorption performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Infrared spectra of porous organic polymers obtained based on different thermal oxidation times of P-BP provided in an embodiment of the present invention;

[0022] Figure 2 Solids of P-BP and P-BP-250-24 provided in the embodiments of the present invention 13 C NMR spectrum;

[0023] Figure 3 Schematic diagram of the reaction route for synthesizing high carboxylic acid density polymers using biphenyl as substrate;

[0024] Figure 4 The nitrogen adsorption-desorption isotherms of the product at 77K were obtained for P-BP at 250℃ in air atmosphere at different times.

[0025] Figure 5 is the infrared spectrum of P-BZ and P-BZ-250-24;

[0026] Figure 6 Nitrogen adsorption-desorption isotherms of P-BZ and P-BZ-250-24 at 77K;

[0027] Figure 7 IR spectra of P-TPB and P-TPB-250-24;

[0028] Figure 8 Nitrogen adsorption-desorption isotherms of P-TPB and P-TPB-250-24 at 77K;

[0029] Figure 9 is the infrared spectrum of P-NAP and P-NAP-250-24;

[0030] Figure 10 Ammonia adsorption-desorption isotherms of different oxidized polymers at 298K. DETAILED DESCRIPTION

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] Example 1: This example provides a method for preparing a porous organic polymer rich in carboxylic acid groups, comprising the following steps:

[0033] S1. Using biphenyl as a substrate and anhydrous aluminum chloride as an activator, 1 g of biphenyl and 3 g of anhydrous aluminum chloride were added to 40 mL of dichloromethane, and then placed in a pressure-resistant sealed autoclave at room temperature. The mixture was stirred under a nitrogen atmosphere and heated to 100° C. for a constant temperature reaction of 24 h to obtain a reaction solution.

[0034] S2. The reaction solution was filtered, and the obtained solid was washed thoroughly with 3M hydrochloric acid and water respectively, and then dried to obtain a precursor polymer P-BP (wherein P represents a polymer and BP represents a substrate biphenyl, the same below). The precursor polymer was then subjected to thermal oxidation at a temperature of 250°C under an air atmosphere for 24 hours to obtain a porous organic polymer rich in carboxylic acid groups, named P-BP-250-24 (250 refers to the reaction temperature, and 24 indicates a heating time of 24 hours, the same below). The carboxylic acid content of P-BP-250-24 was measured to be 6.3 mmol / g by calcium-hydrogen ion exchange, and 17-18 mmol / g of ammonia could be adsorbed at 1 bar and 298K.

[0035] The precursor polymer P-BP prepared according to the above method and its ℃ The infrared spectra of the products at different oxidation times are attached. Figure 1 Compared with the precursor polymer, in the infrared spectrum of the oxidation product, the -1 、1382cm -1 and 1445cm -1 The characteristic peak of saturated CH almost disappears at 1715cm -1 The C=O stretching vibration peaks belonging to the -COOH group appeared at 3600-2500 cm -1 The very broad peak between 1660 and 1690 cm-1 is attributed to the OH stretching vibration of the -COOH group. -1 The C=O stretching vibration peak belonging to diaryl ketone may be covered by the strong signal of -COOH. 13 CCP / MAS NMR spectrum ( Figure 2) shows that the signals originally attributed to -CH3, -CH2-, and -CH2OH carbon groups at 10-80 ppm, and -CHO carbon at 190 ppm, have disappeared, while signals attributable to Ar(C=O)Ar and -COOH carbon have appeared at 182-185 ppm and 162-170 ppm, respectively. These observations indicate that the -CH3, -CH2OH, and -CHO groups in the precursor polymer are oxidized to -COOH groups, and the -CH2- groups in the framework are oxidized to carbonyl groups. For the relevant polymerization reaction formula using biphenyl as a substrate, see Figure 3 The nitrogen adsorption-desorption isotherms of the precursor polymer P-BP at 250℃ and different time were obtained ( Figure 4 ) shows that the longer the reaction time, the less nitrogen adsorption the product has. This indicates that the organic framework structure has changed and the chemical transformation of the groups has occurred.

[0036] The relationship between the thermal oxidation temperature, thermal oxidation time, specific surface area, carboxyl content and ammonia adsorption capacity (298K, 1 bar) of the thermal oxidation product of P-BP in the embodiment is shown in Table 1 below:

[0037] Table 1

[0038]

[0039] Example 2: This example provides a method for preparing a porous organic polymer rich in carboxylic acid groups, comprising the following steps:

[0040] S1. Using benzene as a substrate and anhydrous aluminum chloride as an activator, 1 g of benzene and 3 g of anhydrous aluminum chloride were added to 40 mL of dichloromethane, and then placed in a pressure-resistant sealed autoclave at room temperature. The mixture was stirred under a nitrogen atmosphere and heated to 100° C. for isothermal reaction for 24 h to obtain a reaction solution.

[0041] S2. The reaction solution was filtered, and the obtained solid was washed with 3M hydrochloric acid and water respectively, and then dried to obtain a precursor polymer P-BZ (wherein P represents a polymer, and BZ represents a substrate benzene, the same below). Then, it was placed in an air atmosphere at a temperature of 250°C for thermal oxidation for 24 hours to obtain a porous organic polymer rich in carboxylic acid groups, named P-BZ-250-24 (250 refers to the reaction temperature, and 24 means that the heating time is 24 hours, the same below). Through calcium-hydrogen ion exchange, the carboxylic acid content was measured to be 5.7 mmol / g, and 16-17 mmol / g of ammonia can be adsorbed at 1 bar and 298K. The infrared spectrum of P-BZ-250-24 is similar to that of P-BP-250-24 ( Figure 5 P-BZ-250-24 has almost no nitrogen adsorption in the low pressure area ( Figure 6 ).

[0042] Example 3: This example provides a method for preparing a porous organic polymer rich in carboxylic acid groups, comprising the following steps:

[0043] S1. Using 1,3,5-triphenylbenzene as a substrate and anhydrous aluminum chloride as an activator, 1 g of 1,3,5-triphenylbenzene and 3 g of anhydrous aluminum chloride were added to 40 mL of dichloromethane, and then placed in a pressure-resistant sealed autoclave at room temperature. The mixture was stirred under a nitrogen atmosphere and heated to 100° C. for constant temperature reaction for 24 h to obtain a reaction solution.

[0044] S2. The reaction solution was filtered, and the obtained solid was washed with 3M hydrochloric acid and water respectively, and then dried to obtain a precursor polymer P-TPB (wherein P represents a polymer, TPB represents a substrate 1,3,5-triphenylbenzene, the same below). Then, it was placed in an air atmosphere at a temperature of 250°C for thermal oxidation for 24 hours to obtain a porous organic polymer rich in carboxylic acid groups, named P-TPB-250-24 (250 refers to the reaction temperature, 24 means the heating time is 24 hours, the same below). Through calcium-hydrogen ion exchange, the carboxylic acid content was measured to be 6.2 mmol / g, and 16-17 mmol / g of ammonia can be adsorbed at 1 bar and 298K. The infrared spectrum of P-TPB-250-24 is similar to that of P-BP-250-24 ( Figure 7 ). P-TPB-250-24 has almost no nitrogen adsorption in the low pressure area ( Figure 8 ).

[0045] Example 4: This example provides a method for preparing a porous organic polymer rich in carboxylic acid groups, comprising the following steps:

[0046] S1, take naphthalene as substrate, take anhydrous aluminum chloride as activator, 1g naphthalene and 3g anhydrous aluminum chloride are added in 40mL dichloromethane, then at room temperature add in pressure-resistant sealed kettle, keep stirring under nitrogen atmosphere, be warming up to 100 ℃ and carry out isothermal reaction 24h, obtain reaction solution;

[0047] S2. The reaction solution was filtered, and the obtained solid was washed with 3M hydrochloric acid and water respectively, and then dried to obtain a precursor polymer P-NAP (wherein P represents a polymer, NAP represents a substrate biphenyl, the same below). Then, the precursor polymer was subjected to thermal oxidation treatment at a temperature of 250°C in an air atmosphere for 24 hours to obtain a porous organic polymer rich in carboxylic acid groups, which was named P-NAP-250-24 (250 refers to the reaction temperature, 24 refers to the heating time of 24 hours, the same below). By calcium-hydrogen ion exchange, the carboxylic acid content was measured to be 6.0 mmol / g, and 16-17 mmol / g of ammonia could be adsorbed at 1 bar and 298K. The infrared spectrum of P-NAP-250-24 is similar to that of P-BP-250-24 ( Figure 9 ).

[0048] Example 5: This example provides a method for preparing a porous organic polymer rich in carboxylic acid groups, comprising the following steps:

[0049] S1. Using p-terphenyl as a substrate and anhydrous aluminum chloride as an activator, 1 g of p-terphenyl and 2.5 g of anhydrous aluminum chloride were added to 40 mL of dichloromethane, and then placed in a pressure-resistant sealed autoclave at room temperature. The mixture was stirred under a nitrogen atmosphere and heated to 50° C. for isothermal reaction for 24 h to obtain a reaction solution.

[0050] S2. The reaction solution was filtered, and the obtained solid was washed with 3M hydrochloric acid and water respectively, and then dried to obtain a precursor polymer P-PTP, which was then subjected to thermal oxidation treatment at 150°C in an air atmosphere for 48 hours to obtain a porous organic polymer rich in carboxylic acid groups, which was named P-PTP-150-48.

[0051] Example 6: This example provides a method for preparing a porous organic polymer rich in carboxylic acid groups, comprising the following steps:

[0052] S1. Using mesitylene as a substrate and anhydrous aluminum chloride as an activator, 1 g of mesitylene and 3.5 g of anhydrous aluminum chloride were added to 40 mL of dichloromethane, and then placed in a pressure-resistant sealed autoclave at room temperature. The mixture was stirred under a nitrogen atmosphere and heated to 120° C. for isothermal reaction for 24 h to obtain a reaction solution.

[0053] S2. The reaction solution was filtered, and the obtained solid was washed with 3M hydrochloric acid and water respectively, and then dried to obtain a precursor polymer P-TMB, which was then subjected to thermal oxidation treatment at 230°C in an air atmosphere for 12 hours to obtain a porous organic polymer rich in carboxylic acid groups, which was named P-TMB-230-12.

[0054] Example 7: This example provides a method for preparing a porous organic polymer rich in carboxylic acid groups, comprising the following steps:

[0055] S1. Using anthracene as a substrate and anhydrous aluminum chloride as an activator, 1 g of anthracene and 3.2 g of anhydrous aluminum chloride were added to 40 mL of dichloromethane, and then placed in a pressure-resistant sealed autoclave at room temperature. The mixture was stirred under a nitrogen atmosphere and heated to 110° C. for isothermal reaction for 24 h to obtain a reaction solution.

[0056] S2. The reaction solution was filtered, and the obtained solid was washed with 3M hydrochloric acid and water respectively, and then dried to obtain a precursor polymer P-ANT, which was then subjected to thermal oxidation treatment at 180°C in an air atmosphere for 36 hours to obtain a porous organic polymer rich in carboxylic acid groups, named P-ANT-180-36.

[0057] Example 8: This example provides a method for preparing a porous organic polymer rich in carboxylic acid groups, comprising the following steps:

[0058] S1. Using anthracene as a substrate and anhydrous aluminum chloride as an activator, 1 g of anthracene and 3 g of anhydrous aluminum chloride were added to 40 mL of dichloromethane, and then added to a pressure-resistant sealed autoclave at room temperature. The mixture was stirred under a nitrogen atmosphere and heated to 100° C. for isothermal reaction for 24 h to obtain a reaction solution.

[0059] S2. The reaction solution was filtered, and the obtained solid was washed with 3M hydrochloric acid and water respectively, and then dried to obtain a precursor polymer P-ANT, which was then subjected to thermal oxidation treatment at 250°C in an air atmosphere for 24 hours to obtain a porous organic polymer rich in carboxylic acid groups, named P-ANT-250-24.

[0060] According to the methods provided in Examples 2-8, porous organic polymers rich in carboxylic acid groups were prepared using different types of substrates and different thermal oxidation temperatures and times. The relationships between the specific surface area, carboxyl content, and ammonia adsorption capacity (298K, 1 bar) are shown in Table 2 and Table 3. Figure 10 As shown:

[0061] Table 2

[0062]

[0063] In summary, the preparation method provided by the present invention has controllable properties for the product, and the specific surface area and carboxyl content of the product can be regulated. The obtained porous organic polymer rich in carboxylic acid groups has a high carboxylic acid group content and excellent ammonia adsorption performance.

[0064] Based on the above-mentioned ideal embodiment of the present invention, and through the above description, relevant personnel can make various changes and modifications without departing from the scope of the technical concept of the present invention. The technical scope of the present invention is not limited to the contents of the specification.

Claims

1. A method for preparing a porous organic polymer rich in carboxylic acid groups, characterized in that: The following steps are involved: Using an aromatic compound as a substrate and aluminum chloride as an activator, the aromatic compound and aluminum chloride are added to dichloromethane for constant temperature reaction to obtain a reaction solution; The reaction solution is filtered, the obtained solid is washed, and then subjected to thermal oxidation treatment at a temperature of 150-250° C. to obtain the porous organic polymer rich in carboxylic acid groups.

2. The method for preparing a porous organic polymer rich in carboxylic acid groups according to claim 1, wherein: The mass ratio of the aromatic compound to aluminum chloride is 1:(2.5-5.5).

3. The method for preparing a porous organic polymer rich in carboxylic acid groups according to claim 1, characterized in that: The temperature of the isothermal reaction is 50-120°C.

4. The method for preparing a porous organic polymer rich in carboxylic acid groups according to claim 1, wherein: The environment for thermal oxidation treatment is air atmosphere.

5. The method for preparing a porous organic polymer rich in carboxylic acid groups according to claim 1 or 4, characterized in that: The thermal oxidation treatment time is 0.5-48h.

6. The method for preparing a porous organic polymer rich in carboxylic acid groups according to claim 1, wherein: The aromatic compound is any one of biphenyl, benzene, 1,3,5-triphenylbenzene, naphthalene, p-terphenyl, mesitylene, toluene and anthracene.

7. A porous organic polymer rich in carboxylic acid groups prepared by the preparation method according to any one of claims 1 to 6.

8. The porous organic polymer rich in carboxylic acid groups according to claim 7, characterized in that The carboxyl group content of the porous organic polymer rich in carboxylic acid groups is 2-8 mmol / g.

9. Use of the porous organic polymer rich in carboxylic acid groups as claimed in claim 7 or 8 in ammonia adsorption separation.

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