A method for room-temperature rapid controllable preparation of waste polymer derived three-dimensional porous carbon material

Abstract

The application relates to a method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature, which comprises the following steps: crushing waste polymers; configuring a 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent; mixing the crushed waste polymers with the 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent and adding soluble carbonate as a template agent to form a homogeneous mixture; placing the mixture in a supercritical carbon dioxide reactor for pretreatment to obtain a pretreated mixture, and then drying; grinding and sufficiently mixing the pretreated mixture and a melamine phosphate activator to be uniform; and performing one-step carbonization on the dried mixture in an inert atmosphere to obtain a carbonized product. The application has the advantages of low cost, low temperature, rapidness, controllability, greatly reduced energy consumption, simplified process and the like, and is suitable for industrial popularization and use.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste polymer recycling, and in particular to a method for rapidly and controllably preparing three-dimensional porous carbon materials derived from waste polymers at room temperature. BACKGROUND

[0002] With the wide application of polymer materials, the disposal of their waste has become an important challenge in the fields of environment and resource utilization. In the prior art, the processes for preparing porous carbon materials from waste polymers mainly have the following problems: complex recovery of template materials, high demand for acid washing, complex process flow, cumbersome doping process, low reaction efficiency, and high energy consumption. For example, the patent CN111410184A discloses a method for preparing porous carbon materials by low-temperature carbonization of polyesters, which uses transition metal oxides (such as zinc oxide and iron oxide) as templates. After carbonization, the templates need to be recovered by acid washing (such as dilute sulfuric acid and dilute hydrochloric acid) and high-temperature calcination, resulting in a complex process flow, high requirements for equipment corrosion resistance, increased cost, and complex recovery of template materials. The patent CN101817520B discloses a method for preparing carbon microspheres from waste polymers, which requires high-temperature carbonization (usually ≥ 500℃) before optimizing the material structure, resulting in a long process and high energy consumption. Some existing technologies also require additional high-temperature annealing to regulate the pore structure, further increasing energy consumption. The patent CN119694797A discloses a method for preparing a heteroatom-doped starch-based porous carbon electrode material, which requires the carbonization raw material to be heated, dissolved, and mixed with various heteroatom precursors before being extruded and granulated. After the preparation of carbon microspheres, the material is further processed by high-temperature annealing above 500℃ to prepare layered or porous carbon materials, resulting in a long process and high energy consumption, and requiring additional extruders. The patent CN107399730A discloses a method for preparing bio-based porous carbon materials by one-step carbonization, which has low reaction efficiency, low carbonization conversion rate of waste polymers, long pretreatment time (usually 48 hours), and poor controllability of product morphology. Therefore, there is an urgent need to develop a low-cost, low-temperature, and rapid waste polymer carbonization method to achieve efficient and environmentally friendly preparation of three-dimensional porous carbon materials. SUMMARY

[0003] The technical problem to be solved by the present application is to overcome the above-mentioned defects of the prior art, and to provide a method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature. The method has the advantages of low cost, low temperature, and simplified process. By using recyclable carbonates as templates, acid washing is not required, and the carbonized material can be washed with water. After washing, the liquid can be recycled by passing CO2 gas to recover the carbonates, which can be reused, thus reducing the cost. The method is suitable for industrialization and popularization. In addition, by using supercritical carbon dioxide to assist the 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent system, the polymer pretreatment can be completed rapidly at room temperature and low pressure, greatly reducing the energy consumption. By mixing with phosphorus cyanamide as an activator, the process is simple, controllable, and highly reproducible, and the morphology is easy to control. In addition, the carbonization temperature is relatively low, controlled at 250-500℃, and the nitrogen and phosphorus doped porous carbon material can be controllably prepared by one-step carbonization, which has a simple process and lower energy consumption.

[0004] The present application is realized by the following technical solutions:

[0005] A method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature, comprising the following steps:

[0006] S1, crushing the waste polymers;

[0007] S2, configuring a eutectic solvent, mixing 1,5-diazabicyclo[4.3.0]nonene / urea system to obtain 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent;

[0008] S3, mixing the crushed waste polymers in S1 with the 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent obtained in S2, adding soluble carbonates as a template agent to form a homogeneous mixture;

[0009] S4, placing the mixture in a supercritical carbon dioxide reactor for pretreatment to obtain a pretreated mixture, and then drying;

[0010] S5, grinding and thoroughly mixing the pretreated mixture with phosphorus cyanamide activator;

[0011] S6, one-step carbonization of the dried mixture under an inert atmosphere to obtain a carbonized product.

[0012] As an optimization, the waste polymers in S1 are one of polyethylene terephthalate, polyethylene, and polystyrene.

[0013] As an optimization, the waste polymers in S1 are crushed to 40-60 mesh.

[0014] As optimization, the molar ratio of the 1,5-diazabicyclo[4.3.0]nonene / urea system in S2 is 1:1-5:1.

[0015] As optimization, the S3 soluble carbonate is sodium carbonate, potassium carbonate or a mixture thereof.

[0016] As optimization, the S3 specific step is: 5 g of the pulverized waste polymer is mixed with 15-40 g of 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent, 5-15 g of a soluble carbonate is added as a template agent to form a homogeneous mixture.

[0017] As optimization, the pretreatment conditions in S4 are: temperature 30-50℃, pressure 7-15 MPa, pretreatment time 60 s to 15 min.

[0018] As optimization, the drying temperature in S4 is 60℃.

[0019] As optimization, in S5, the pretreated mixture and melamine phosphate activator are ground and mixed uniformly in a ratio of 10:1-10:9.

[0020] As optimization, the carbonization conditions in S6 are: carbonization temperature 250-500℃, holding time 0.5-3 h.

[0021] The present application has the following beneficial effects.

[0022] The present application provides a method for rapidly and controllably preparing a waste polymer-derived three-dimensional porous carbon material at room temperature, which has the following beneficial effects.

[0023] The present application uses recyclable carbonate as a template, does not need acid washing, reduces the risk of equipment corrosion and wastewater treatment cost, and only needs water washing after carbonization to remove the template. After washing, the liquid can be recycled by passing CO2 gas to recover the carbonate, which is suitable for industrialized use. The process is simple, controllable, repeatable, and the morphology is easy to control.

[0024] The present application can precisely control the specific surface area (500-3000 m 2 / g) of the porous carbon material, the pore size distribution (microporous-mesoporous composite structure) and the layered morphology by adjusting the type of carbonate, the supercritical carbon dioxide treatment time and the carbonization temperature.

[0025] The porous carbon material doped with nitrogen and phosphorus prepared by one-step carbonization has short reaction period, low carbonization temperature (controlled in 250-500 DEG C), simple process, and 30%-50% reduced comprehensive energy consumption, and is suitable for large-scale continuous production.

[0026] The application utilizes recyclable carbonate as a template, does not need acid washing, reduces the corrosion risk of equipment and the wastewater treatment cost, removes the template by only water washing after carbonization, and recycles the carbonate by passing CO2 gas after washing; the 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent can efficiently catalyze the alcoholysis swelling of waste polymers, and the gas phase diffusion and viscosity of supercritical carbon dioxide are beneficial to the rapid diffusion and penetration of the soluble carbonate template into the swollen waste polymer matrix, so that the pretreatment is rapidly completed at room temperature; then, the nitrogen and phosphorus doped porous carbon material with high specific surface area and developed hierarchical pore structure is finally obtained by one-step carbonization after grinding and mixing with melamine phosphate as an activator. BRIEF DESCRIPTION OF DRAWINGS

[0027] The method for rapidly and controllably preparing the three-dimensional porous carbon material derived from waste polymers at room temperature is further described below in combination with the drawings:

[0028] Figure 1 is the SEM image of Example 1 of the application;

[0029] Figure 2 is the SEM image of Example 2 of the application;

[0030] Figure 3 is the SEM image of Example 3 of the application;

[0031] Figure 4 is the SEM image of Comparative Example 1 of the application;

[0032] Figure 5 is the SEM image of Comparative Example 2 of the application;

[0033] Figure 6 is the SEM image of Comparative Example 3 of the application;

[0034] Figure 7 is the SEM image of Comparative Example 4 of the application. DETAILED DESCRIPTION

[0035] The application is further described in detail below in combination with the drawings and embodiments. It is particularly pointed out that the following embodiments are only used to illustrate the application, but do not limit the scope of the application. Similarly, the following embodiments are only part of the embodiments of the application rather than all the embodiments of the application, and all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application. Embodiment

[0036] (1) The waste polyethylene is crushed to 40-60 mesh.

[0037] (2) A eutectic solvent, namely a 1,5-diazabicyclo[4.3.0]nonene (DBN) / urea system, is prepared by mixing at a molar ratio of 1:1 to obtain a DBN / urea solvent.

[0038] (3) 5 g of the crushed waste polymer is mixed with 20 g of the eutectic solvent, and 5 g of sodium carbonate is added as a template to form a homogeneous mixture.

[0039] (4) The mixture is placed in a supercritical carbon dioxide reactor and treated at 35°C and 8 MPa for 60 s to obtain a pretreated mixture, which is dried at 60°C.

[0040] (5) The pretreated mixture 10 g and a melamine phosphate activator 2 g are ground and mixed uniformly;

[0041] (6) The pretreated mixture is subjected to one-step carbonization under an inert atmosphere (such as nitrogen) at a carbonization temperature of 300°C for 2 h to obtain a nitrogen-phosphorus-doped carbonized product. Embodiment

[0042] (1) The waste polyethylene terephthalate is crushed to 40-60 mesh.

[0043] (2) A eutectic solvent, namely a 1,5-diazabicyclo[4.3.0]nonene (DBN) / urea system, is prepared by mixing at a molar ratio of 3:1 to obtain a DBN / urea solvent.

[0044] (3) 5 g of the crushed waste polymer is mixed with 30 g of the eutectic solvent, and 8 g of potassium carbonate is added as a template to form a homogeneous mixture.

[0045] (4) The mixture is placed in a supercritical carbon dioxide reactor and treated at 45°C and 10 MPa for 5 min to obtain a pretreated mixture, which is dried at 60°C.

[0046] (5) The pretreated mixture 10 g and a melamine phosphate activator 6 g are ground and mixed uniformly;

[0047] (6) The pretreated mixture is subjected to one-step carbonization under an inert atmosphere (such as nitrogen) at a carbonization temperature of 450°C for 1.5 h to obtain a nitrogen-phosphorus-doped carbonized product. Example

[0048] (1) The waste polystyrene was crushed to 40-60 mesh.

[0049] (2) The eutectic solvent, i.e., 1,5-diazabicyclo[4.3.0]nonene (DBN) / urea system, was configured by mixing at a molar ratio of 5:1 to obtain a DBN / urea solvent.

[0050] (3) 5 g of the crushed waste polymer was mixed with 35 g of the eutectic solvent, and 15 g of a mixture of sodium carbonate and potassium carbonate was added as a template agent to form a homogeneous mixture.

[0051] (4) The mixture was placed in a supercritical carbon dioxide reactor and treated at 40°C and 15 MPa for 10 min to obtain a pretreated mixture, which was dried at 60°C.

[0052] (5) The pretreated mixture 10 g and melamine phosphate activator 8 g were ground and mixed evenly;

[0053] (6) The pretreated mixture was carbonized in an inert atmosphere (such as nitrogen) at a carbonization temperature of 500°C for 1.0 h to obtain a nitrogen and phosphorus doped carbonization product.

[0054] Comparative Example 1

[0055] Different from Example 2, Comparative Example 1 did not add 30 g of 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent mixture, and the other step conditions were the same as those of Example 2.

[0056] Comparative Example 2

[0057] Different from Example 2, Comparative Example 2 did not add 8 g of soluble carbonate as a template agent, and the other step conditions were the same as those of Example 2.

[0058] Comparative Example 3

[0059] Different from Example 2, Comparative Example 3 did not place the mixture in a supercritical carbon dioxide reactor and treat it at 45°C and 10 MPa for 5 min to obtain a pretreated mixture, which was dried at 60°C; the other step conditions were the same as those of Example 2.

[0060] Comparative Example 4

[0061] Different from Example 2, Comparative Example 4 did not add melamine phosphate activator, and the other step conditions were the same as those of Example 2.

[0062] From the above table, the comparative example 1 does not add 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent mixture, the waste polymer matrix cannot be alcoholysis swelled, the template agent cannot effectively penetrate into the waste polymer matrix, the porous structure is less, and the specific surface area is only 374 m 2 / g; the comparative example 2 does not add a soluble carbonate as a template agent, lacks the realization of three-dimensional porous carbon materials in the space limited by the template, reduces the specific surface area of the carbon material, and the specific surface area is only 456 m 2 / g; the comparative example 3 mixture is not placed in a supercritical carbon dioxide reactor, and the shearing effect of the supercritical carbon dioxide fluid in the pretreatment process makes the honeycomb structure with cavities less, and the specific surface area is only 436 m 2 / g; the comparative example 4 does not add melamine phosphate activator, resulting in a large number of defect sites for ion adsorption during carbonization of nitrogen and phosphorus heteroatoms, although the specific surface area is larger, reaching 1786 m 2 / g, but the specific capacitance of the carbon material is only 163 F / g. The specific surface area of the three-dimensional porous carbon material prepared by the present application is between 1889~2453 m 2 / g, the specific capacitance is between 256~362 F / g at a current density of 0.5 A / g, and the nitrogen and phosphorus doped porous carbon material with high specific surface area and developed hierarchical pore structure has a honeycomb structure with cavities, which provides a large number of effective channels for ion and electron transmission. As can be seen, the present application uses 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent to efficiently swell the waste polymer matrix, and cooperates with supercritical carbon dioxide to complete the diffusion and penetration of the template agent soluble carbonate in the matrix, the pretreatment operation has the characteristics of high efficiency, low cost, easy operation, commercialization and easy recovery, etc., and then mixed with melamine phosphate as an activator, the nitrogen and phosphorus elements can be doped in the cavity honeycomb structure limited by the template, and a nitrogen and phosphorus doped porous carbon material with high specific surface area and developed hierarchical pore structure can be obtained, the carbonization temperature is lower, the process is simple, the comprehensive energy consumption is reduced, and it is suitable for large-scale continuous production.

[0063] Unlike the prior art, the present application provides a method for rapidly and controllably preparing a waste polymer derived three-dimensional porous carbon material at room temperature, comprising the following steps:

[0064] S1, crushing the waste polymer;

[0065] S2, configuring a eutectic solvent, mixing 1,5-diazabicyclo[4.3.0]nonene / urea system to obtain 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent;

[0066] S3, mixing the waste polymer crushed in S1 with the 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent obtained in S2, adding a soluble carbonate as a template to form a homogeneous mixture;

[0067] S4, placing the mixture in a supercritical carbon dioxide reactor for pretreatment to obtain a pretreated mixture, and then drying;

[0068] S5, grinding and thoroughly mixing the pretreated mixture and melamine phosphate activator;

[0069] S6, carbonizing the dried mixture in an inert atmosphere to obtain a carbonized product.

[0070] The method has the advantages of low cost, low temperature and rapidness, and process simplification, and by using recyclable carbonate as a template, acid washing is not needed, and the carbonized material can be washed, and the liquid can be recycled by passing CO2 gas to recover the carbonate, which is more cost-effective and suitable for industrialization and popularization. In addition, by using supercritical carbon dioxide to assist the 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent system, the polymer pretreatment can be completed quickly at room temperature and low pressure, which greatly reduces the energy consumption. The process of mixing with melamine phosphate as an activator is simple, controllable, and has high repeatability, and the morphology is easy to control. In addition, the carbonization temperature is relatively low, controlled at 250-500℃, and the nitrogen and phosphorus doped porous carbon material can be prepared by one-step carbonization, which is simple in process and low in energy consumption.

[0071] The above description shows the main features, basic principles, and advantages of the present application. It is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments or examples, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the above embodiments or examples should be regarded as exemplary and non-limiting. The scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved. Any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present application, without departing from the technical principles of the present application, should fall within the scope of the patent protection of the present application.

Claims

1. A method for room-temperature rapid controllable preparation of waste polymer derived three-dimensional porous carbon materials, characterized in that, The method comprises the following steps: S1, crushing the waste polymer; S2, configuring a eutectic solvent, mixing 1,5-diazabicyclo[4.3.0]nonene / urea system to obtain 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent; S3, mixing the crushed waste polymer in S1 and the 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent obtained in S2, adding soluble carbonate as a template to form a homogeneous mixture; S4, placing the mixture in a supercritical carbon dioxide reactor for pretreatment to obtain a pretreated mixture, and then drying; S5, grinding and fully mixing the pretreated mixture and melamine phosphate activator uniformly; S6, one-step carbonization of the dried mixture under inert atmosphere to obtain a carbonized product; the carbonization conditions are: carbonization temperature 250-500℃, holding time 0.5-3h.

2. The method of claim 1, wherein the method is characterized by: The waste polymer in S1 is one of polyethylene terephthalate, polyethylene, and polystyrene.

3. The method of claim 2, wherein the method is characterized by: The waste polymer in S1 is crushed to 40-60 mesh.

4. The method of claim 1, wherein the method is a room-temperature rapid controllable preparation method of waste polymer-derived three-dimensional porous carbon materials. The molar ratio of 1,5-diazabicyclo[4.3.0]nonene / urea system in S2 is 1:1-5:

1.

5. The method of claim 1, wherein the method is a room-temperature rapid controllable preparation method of waste polymer-derived three-dimensional porous carbon materials. The soluble carbonate in S3 is sodium carbonate, potassium carbonate, or a mixture thereof.

6. The method of claim 5, wherein the method is a room-temperature rapid controllable preparation method of waste polymer-derived three-dimensional porous carbon materials. The specific steps of S3 are: mixing 5 g of crushed waste polymer with 15-40 g of 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent, adding 5-15 g of soluble carbonate as a template to form a homogeneous mixture.

7. The method of claim 1, wherein the method is a room-temperature rapid controllable preparation method of waste polymer-derived three-dimensional porous carbon materials. The pretreatment conditions in S4 are: temperature 30-50℃, pressure 7-15MPa, pretreatment time 60s to 15min.

8. The method of claim 7, wherein the method is a room-temperature rapid controllable preparation method of waste polymer-derived three-dimensional porous carbon materials. The drying temperature in S4 is 60℃.

9. The method for rapid and controllable preparation of waste polymer-derived three-dimensional porous carbon materials at room temperature as described in claim 1, characterized in that: In S5, the pretreated mixture and melamine phosphate activator are ground and fully mixed uniformly at a ratio of 10:1-10:9.

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