Method for rapidly and controllably preparing three-dimensional porous carbon material derived from waste macromolecules at room temperature

Abstract

The invention relates to a method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste macromolecules at room temperature. The method comprises the following steps: crushing the waste macromolecules; the preparation method comprises the following steps: preparing a 1, 5-diazabicyclo [4.3. 0] nonene / urea eutectic solvent; the method comprises the following steps: mixing crushed waste macromolecules with a 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 reaction kettle for pretreatment to obtain a pretreated mixture, and then drying the pretreated mixture; grinding the pretreated mixture and a melamine phosphate activating agent, and fully and uniformly mixing; and performing one-step carbonization on the dried mixture in an inert atmosphere to obtain a carbonized product. The method has the advantages of low cost, low temperature, rapidness, controllability, great reduction of energy consumption, process simplification and the like, and is suitable for industrial popularization and application.

Description

Technical Field

[0001] The present invention relates to the technical field of waste polymer recycling and utilization, and particularly relates to a method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature. Background Art

[0002] With the wide application of polymer materials, the treatment 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 template material recovery, high pickling requirements, complex process flows, cumbersome doping processes, low reaction efficiency, and high energy consumption. For example, in the method for preparing a porous carbon material by low-temperature carbonization of polyester disclosed in Chinese Patent CN111410184A, transition metal oxides (such as zinc oxide and iron oxide) are used as templates, and after carbonization, the templates need to be recovered by pickling (such as dilute sulfuric acid and dilute hydrochloric acid) and high-temperature calcination, resulting in a cumbersome process flow, high requirements for equipment corrosion resistance, increased costs, and complex template material recovery. The process conditions of the method for making carbon microspheres from waste polymers disclosed in Chinese Patent CN101817520B are harsh. It is necessary to first perform high-temperature carbonization (usually ≥500 °C) and then optimize the material structure, with a long and energy-consuming process; some prior arts also require additional high-temperature annealing treatment to regulate the pore structure, further increasing energy consumption. The method for preparing a heteroatom-doped starch-based porous carbon electrode material disclosed in Chinese Patent CN 119694797A requires first heating, dissolving, and mixing the raw materials to be carbonized with a variety of heteroatom precursors and then extruding and granulating. After preparing carbon microspheres, it is still necessary to perform high-temperature annealing above 500 °C and further process to prepare a layered or porous carbon material, with a long and energy-consuming process and the need for an additional extruder. The method for preparing a bio-based porous carbon material by one-step carbonization disclosed in Chinese Patent CN107399730A has low reaction efficiency, low carbonization conversion rate of waste polymers, a long pretreatment time (usually 48 hours), and poor controllability of the product morphology. Therefore, there is an urgent need to develop a low-cost, low-temperature, rapid, and process-simplified method for carbonizing waste polymers to achieve the preparation of efficient and environmentally friendly three-dimensional porous carbon materials. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for rapidly and controllably preparing three-dimensional porous carbon materials derived from waste polymers at room temperature. The method has the advantages of low cost, low temperature and rapid speed, and simplified process. By using recyclable carbonate as a template, no acid washing is required, and the carbonized material can be washed with water. The washed liquid can be recycled by passing CO2 gas to recover carbonate, which is reused, and the cost is lower, which is suitable for industrial promotion and use. In addition, supercritical carbon dioxide is used to assist 1,5-diazabicyclo[4.3.0]nonene / urea low eutectic solvent system to quickly complete polymer pretreatment at room temperature and low pressure, greatly reducing energy consumption, and grinding and mixing with melamine phosphate as an activator. The process is simple, controllable, highly repeatable, and the morphology is easy to control. In addition. The carbonization temperature is low, controlled at 250-500°C, and the porous carbon material doped with nitrogen and phosphorus can be prepared in a controlled manner through one-step carbonization, with a simple process and lower energy consumption.

[0004] The present invention is achieved through the following technical solutions: A method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature comprises the following steps: S1, crushing the waste polymer; S2, preparing a low eutectic solvent, mixing the 1,5-diazabicyclo[4.3.0]nonene / urea system to obtain a 1,5-diazabicyclo[4.3.0]nonene / urea low eutectic solvent; S3, mixing the crushed waste polymer in S1 with the 1,5-diazabicyclo[4.3.0]nonene / urea low eutectic solvent obtained in S2, adding a 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 the pretreated mixture and the melamine phosphate activator and mixing them uniformly; S6. Carbonizing the dried mixture in an inert atmosphere to obtain a carbonized product.

[0005] As an optimization, the waste polymer in S1 is one of polyethylene terephthalate, polyethylene, and polystyrene.

[0006] As an optimization, the waste polymer is crushed into 40-60 meshes in S1.

[0007] As an optimization, the molar ratio of the 1,5-diazabicyclo[4.3.0]nonene / urea system in S2 is 1:1~5:1.

[0008] As an optimization, the S3 soluble carbonate is sodium carbonate, potassium carbonate or a mixture thereof.

[0009] As an optimization, the specific steps of S3 are as follows: Mix 5 g of pulverized waste polymers with 15 - 40 g of 1,5 - diazabicyclo[4.3.0]nonene / urea eutectic solvent, and add 5 - 15 g of soluble carbonate as a templating agent to form a homogeneous mixture.

[0010] As an optimization, the pretreatment conditions in S4 are: temperature 30 - 50 °C, pressure 7 - 15 MPa, and pretreatment time 60 s to 15 min.

[0011] As an optimization, the drying temperature in S4 is 60 °C.

[0012] As an optimization, in S5, the pretreated mixture and melamine phosphate activating agent are ground and thoroughly mixed in a ratio of 10:1 - 10:9.

[0013] As an optimization, the carbonization conditions in S6 are: carbonization temperature 250 - 500 °C, and heat preservation time 0.5 - 3 h.

[0014] The beneficial effects of the present invention are as follows: A method for rapidly and controllably preparing three - dimensional porous carbon materials derived from waste polymers at room temperature provided by the present invention has the following beneficial effects.

[0015] By using recyclable carbonate as a template, the present invention does not require pickling, reducing the risk of equipment corrosion and the cost of wastewater treatment. After carbonization, the template can be removed only by washing with water, and the washing liquid can recover carbonate by passing CO2 gas for reuse, with lower cost, and is suitable for industrial promotion. Through supercritical carbon dioxide - assisted 1,5 - diazabicyclo[4.3.0]nonene / urea eutectic solvent system, the polymer pretreatment is rapidly completed at room temperature and low pressure, significantly reducing energy consumption. By grinding and mixing with melamine phosphate as an activating agent, the process is simple, with good controllability, high repeatability, and easy morphology regulation.

[0016] By adjusting the type of carbonate, the supercritical carbon dioxide treatment time, and the carbonization temperature, the present invention can precisely control the specific surface area (500 - 3000 m 2 / g), pore size distribution (micropore - mesopore composite structure), and layered morphology of the porous carbon material.

[0017] The present invention realizes the controllable preparation of nitrogen - and phosphorus - doped porous carbon materials through one - step carbonization, shortens the reaction cycle, has a relatively low carbonization temperature, controlled at 250 - 500 °C, the process is simple, the comprehensive energy consumption is reduced by 30% - 50%, and it is suitable for large - scale continuous production.

[0018] The invention uses recyclable carbonate as a template, does not require acid washing, reduces equipment corrosion risk and wastewater treatment costs, and only needs water washing to remove the template after carbonization. The carbonate can be recovered by passing CO2 gas through the liquid after washing; 1,5-diazabicyclo[4.3.0]nonene / urea low eutectic solvent is used to efficiently catalyze the alcoholysis and swelling of waste polymers, and then the gas phase diffusion and viscosity of supercritical carbon dioxide are used to facilitate the rapid diffusion and penetration of the template agent soluble carbonate into the swollen waste polymer matrix, and the pretreatment is quickly completed at room temperature; then, the porous carbon material doped with nitrogen and phosphorus is obtained by grinding and mixing with melamine phosphate as an activator and then carbonizing in one step to finally obtain a nitrogen-phosphorus doped porous carbon material with a high specific surface area and a developed hierarchical pore structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following is a further description of a method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature in conjunction with the accompanying drawings: Figure 1 is a SEM image of Example 1 of the present invention; Figure 2 is a SEM image of Example 2 of the present invention; Figure 3 is a SEM image of Example 3 of the present invention; Figure 4 is a SEM image of Comparative Example 1 of the present invention; Figure 5 It is the SEM picture of comparative example 2 of the present invention; Figure 6 is a SEM image of Comparative Example 3 of the present invention; Figure 7 It is the SEM picture of comparative example 4 of the present invention. DETAILED DESCRIPTION

[0020] The present application is further described in detail below in conjunction with the accompanying drawings and implementation methods. It is particularly noted that the following implementation methods are only used to illustrate the present application, but do not limit the scope of the present application. Similarly, the following implementation methods are only some implementation methods of the present application rather than all implementation methods. All other implementation methods obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Example

[0021] (1) Crush the waste polyethylene into 40~60 mesh.

[0022] (2) preparing a low eutectic solvent, i.e., a 1,5-diazabicyclo[4.3.0]nonene (1,5-diazabicyclo[4.3.0]nonene) / urea system, and mixing them in a 1:1 molar ratio to obtain a 1,5-diazabicyclo[4.3.0]nonene / urea solvent.

[0023] (3) Mix 5 g of the crushed waste polymers with 20 g of the eutectic solvent, and add 5 g of sodium carbonate as a templating agent to form a homogeneous mixture.

[0024] (4) Place the mixture in a supercritical carbon dioxide reactor and treat it at 35 °C and 8 MPa for 60 s to obtain a pretreated mixture, and dry it at 60 °C.

[0025] (5) Grind and thoroughly mix 10 g of the pretreated mixture and 2 g of the melamine phosphate activator; (6) Perform one-step carbonization of the pretreated mixture under an inert atmosphere (such as nitrogen), with a carbonization temperature of 300 °C and a holding time of 2 h to obtain a nitrogen and phosphorus doped carbonized product. Example

[0026] (1) Crush the waste polyethylene terephthalate to 40 - 60 mesh.

[0027] (2) Prepare a eutectic solvent, namely a 1,5-diazabicyclo[4.3.0]nonene (1,5-diazabicyclo[4.3.0]nonene) / urea system, and mix it in a molar ratio of 3:1 to obtain a 1,5-diazabicyclo[4.3.0]nonene / urea solvent.

[0028] (3) Mix 5 g of the crushed waste polymers with 30 g of the eutectic solvent, and add 8 g of potassium carbonate as a templating agent to form a homogeneous mixture.

[0029] (4) 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, and dry it at 60 °C.

[0030] (5) Grind and thoroughly mix 10 g of the pretreated mixture and 6 g of the melamine phosphate activator; (6) Perform one-step carbonization of the pretreated mixture under an inert atmosphere (such as nitrogen), with a carbonization temperature of 450 °C and a holding time of 1.5 h to obtain a nitrogen and phosphorus doped carbonized product. Example

[0031] (1) Crush the waste polystyrene to 40 - 60 mesh.

[0032] (2) Prepare a eutectic solvent, namely a 1,5-diazabicyclo[4.3.0]nonene (1,5-diazabicyclo[4.3.0]nonene) / urea system, and mix it in a molar ratio of 5:1 to obtain a 1,5-diazabicyclo[4.3.0]nonene / urea solvent.

[0033] (3) Mix 5 g of crushed waste polymers with 35 g of eutectic solvent, and add 15 g of a mixture of sodium carbonate and potassium carbonate as a template agent to form a homogeneous mixture.

[0034] (4) Place the mixture in a supercritical carbon dioxide reactor and treat it at 40 °C and 15 MPa for 10 min to obtain a pretreated mixture, which is then dried at 60 °C.

[0035] (5) Grind and thoroughly mix 10 g of the pretreated mixture and 8 g of melamine phosphate activator evenly; (6) Perform one-step carbonization of the pretreated mixture under an inert atmosphere (such as nitrogen), with a carbonization temperature of 500 °C and a holding time of 1.0 h to obtain a nitrogen and phosphorus-doped carbonized product.

[0036] Comparative Example 1 Different from Example 2, in Comparative Example 1, 30 g of 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent was not added, and the conditions of other steps were the same as those in Example 2.

[0037] Comparative Example 2 Different from Example 2, in Comparative Example 2, 8 g of soluble carbonate was not added as a template agent, and the conditions of other steps were the same as those in Example 2.

[0038] Comparative Example 3 Different from Example 2, in Comparative Example 3, the mixture was not placed in a supercritical carbon dioxide reactor and treated at 45 °C and 10 MPa for 5 min to obtain a pretreated mixture, which was then dried at 60 °C; the conditions of other steps were the same as those in Example 2.

[0039] Comparative Example 4 Different from Example 2, in Comparative Example 4, melamine phosphate activator was not added, and the conditions of other steps were the same as those in Example 2. As can be seen from the above table, in Comparative Example 1, 1,5-diazabicyclo[4.3.0]nonene / urea eutectic solvent was not added, and the waste polymer matrix could not be alcoholyzed and swollen, and the template agent could not effectively penetrate into the interior of the waste polymer matrix, resulting in fewer porous structures and a specific surface area of only 374 m 2 / g; in Comparative Example 2, soluble carbonate was not added as a template agent, lacking the realization of three-dimensional porous carbon materials within the space confined by the template, reducing the specific surface area of the carbon material, and the specific surface area was only 456 m 2 / g; in Comparative Example 3, the mixture was not placed in a supercritical carbon dioxide reactor, and the lack of the tailoring effect of supercritical carbon dioxide fluid during the pretreatment process resulted in fewer honeycomb structures with cavities, and the specific surface area was only 436 m 2 / g; Comparative example 4 did not add melamine phosphate activator, resulting in a large number of defect sites for ion adsorption generated by nitrogen and phosphorus heteroatoms during the carbonization process. Although the specific surface area was relatively large, reaching 1786 m 2 / g, the specific capacitance of the carbon material was relatively low, only 163 F / g. The specific surface area of the three-dimensional porous carbon material prepared by the present invention is between 1889 and 2453 m 2 / g. At a current density of 0.5 A / g, the specific capacitance is between 256 and 362 F / g. The nitrogen and phosphorus-doped porous carbon material with a high specific surface area and a developed hierarchical pore structure has a honeycomb structure with holes, providing a large number of effective channels for the transmission of ions and electrons. Thus, the present invention uses 1,5-diazabicyclo[4.3.0]nonene / urea deep 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, commercially available and easy recovery, etc. After that, by grinding and mixing with melamine phosphate as the activator, the doping of nitrogen and phosphorus elements can be completed in the cavity honeycomb structure confined by the template, obtaining a nitrogen and phosphorus-doped porous carbon material with a high specific surface area and a developed hierarchical pore structure. The carbonization temperature is relatively low, the process is simple, the comprehensive energy consumption is reduced, and it is suitable for large-scale continuous production.

[0040] Differing from the prior art, a method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature provided by the present invention includes the following steps: S1. Crushing the waste polymer; S2. Preparing a deep eutectic solvent, mixing the 1,5-diazabicyclo[4.3.0]nonene / urea system to obtain a 1,5-diazabicyclo[4.3.0]nonene / urea deep eutectic solvent; S3. Mixing the crushed waste polymer in S1 with the 1,5-diazabicyclo[4.3.0]nonene / urea deep eutectic solvent obtained in S2, adding a soluble carbonate as a template agent 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 thoroughly mixing the pretreated mixture with a melamine phosphate activator; S6. Carrying out one-step carbonization of the dried mixture under an inert atmosphere to obtain a carbonized product.

[0041] This method has the advantages of low cost, rapidity at low temperature, and process simplification. By using recyclable carbonate as a template, pickling is not required, and the carbonized material can be washed with water. After washing, the liquid can recover carbonate by passing CO2 gas and be reused, resulting in lower costs and being suitable for industrial promotion. Additionally, through supercritical carbon dioxide-assisted 1,5-diazabicyclo[4.3.0]nonene / urea deep eutectic solvent system, high-molecular pretreatment can be rapidly completed at room temperature and low pressure, significantly reducing energy consumption. Mixing by grinding with melamine phosphate as an activator has a simple process, good controllability, high repeatability, and easy morphology regulation. Moreover, the carbonization temperature is relatively low, controlled at 250-500 °C. The controllable preparation of nitrogen and phosphorus-doped porous carbon materials can be achieved through one-step carbonization, with a simple process and lower energy consumption.

[0042] The above description shows the main features, basic principles, and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments or examples, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, the above embodiments or examples should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical principle of the present invention shall fall within the scope of the patent protection of the present invention.

Claims

1. A method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature, characterized in that, It includes the following steps: S1. Crush the waste polymers; S2. Prepare a deep eutectic solvent by mixing the 1,5-diazabicyclo[4.3.0]nonene / urea system to obtain a 1,5-diazabicyclo[4.3.0]nonene / urea deep eutectic solvent; S3. Mix the crushed waste polymers in S1 with the 1,5-diazabicyclo[4.3.0]nonene / urea deep eutectic solvent obtained in S2, and add a soluble carbonate as a templating agent to form a homogeneous mixture; S4. Place the mixture in a supercritical carbon dioxide reactor for pretreatment to obtain a pretreated mixture, and then dry it; S5. Grind and thoroughly mix the pretreated mixture and a melamine phosphate activator evenly; S6. Perform one-step carbonization on the dried mixture under an inert atmosphere to obtain a carbonized product.

2. The method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature according to claim 1, wherein: The waste polymers in S1 are one of polyethylene terephthalate, polyethylene, and polystyrene.

3. The method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature according to claim 2, wherein: In S1, the waste polymers are crushed to 40 - 60 meshes.

4. The method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature according to claim 1, characterized in that: In S2, the molar ratio of the 1,5-diazabicyclo[4.3.0]nonene / urea system is 1:1 - 5:

1.

5. The method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature according to claim 1, characterized in that: The soluble carbonate in S3 is sodium carbonate, potassium carbonate, or a mixture thereof.

6. The method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature according to claim 5, wherein The specific steps of S3 are: Mix 5 g of the crushed waste polymers with 15 - 40 g of the 1,5-diazabicyclo[4.3.0]nonene / urea deep eutectic solvent, and add 5 - 15 g of a soluble carbonate as a templating agent to form a homogeneous mixture.

7. A method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature as claimed in claim 1, characterized in that, The pretreatment conditions in S4 are: temperature 30 - 50°C, pressure 7 - 15 MPa, and pretreatment time 60 s to 15 min.

8. A method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature according to claim 7, characterized in that: The drying temperature in S4 is 60°C.

9. The method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature according to claim 1, wherein: In S5, the pretreated mixture and the melamine phosphate activator are ground and thoroughly mixed evenly at a ratio of 10:1 - 10:

9.

10. A method for rapidly and controllably preparing a three-dimensional porous carbon material derived from waste polymers at room temperature according to claim 1, characterized in that, The carbonization conditions in S6 are: carbonization temperature 250 - 500°C, and heat preservation time 0.5 - 3 h.

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