Porous carbon material prepared based on quenching type deflagration method and application thereof

Abstract

This invention belongs to the technical field of carbon-based material preparation and solid waste resource utilization, specifically involving a porous carbon material prepared based on a quenching-type deflagration method and its application. This invention uses waste circuit boards as raw material and utilizes a tube furnace with a pull-out device. After preheating, the raw material is rapidly pushed in to initiate an instantaneous deflagration reaction. After the reaction, the ceramic boat is immediately pulled out for rapid cooling, completing carbonization and activation in one step. Specifically, the circuit board's own resin is used as the carbon source, and metallic copper is used as an in-situ self-activating agent. Instantaneous deflagration forms a multi-level porous structure, and rapid quenching effectively locks in the highly active elemental copper and cuprous oxide generated at high temperature, as well as carbon skeleton defects, preventing oxidation and agglomeration. The obtained porous carbon has a specific surface area ≥300 m². 2 / g、I D / I G With a copper content of ≥14%, it achieves a pollutant removal rate of over 90%, realizing the high-value utilization of electronic waste. It also features the characteristics of not requiring external activators and having excellent catalytic performance.

Description

Technical Field

[0001] This invention belongs to the technical field of carbon-based material preparation and solid waste resource utilization, specifically relating to a porous carbon material prepared based on a quenching-type deflagration method and its application. Background Technology

[0002] Waste printed circuit boards are a significant component of electronic waste, with non-metallic parts (mainly epoxy resin and fiberglass) accounting for over 70% of their mass. Traditional disposal methods, such as landfilling or incineration, not only waste resources but also easily generate harmful gases such as dioxins.

[0003] Utilizing waste circuit boards to prepare porous carbon is an effective way to realize its resource utilization. Existing technologies are mainly divided into two categories: one is a two-step process of carbonization followed by activation, such as carbonizing the non-metallic parts of the circuit board and then activating them with activating agents such as KOH; the other is to directly prepare porous carbon by high-temperature pyrolysis.

[0004] However, existing methods have significant shortcomings. First, traditional pyrolysis has a slow heating rate and slow gas escape, resulting in limited pore-forming effect and typically low specific surface area of ​​the obtained porous carbon. Studies have reported that the specific surface area of ​​waste printed circuit boards activated at 700℃ is only about 180 m². 2 / g. Secondly, after the reaction, the furnace is usually cooled slowly, causing the active metal species formed during pyrolysis to be oxidized or agglomerated and sintered during the cooling process, losing their catalytic activity and affecting the pore structure of the final porous carbon and its degradation performance for specific pollutants. In addition, most existing processes require the addition of external activators, increasing costs and processing steps.

[0005] Therefore, developing a high-performance porous carbon preparation method that is simple in process, requires no external activator, and can effectively retain active species is of great practical significance. Summary of the Invention

[0006] To address the needs of existing technologies, the purpose of this invention is to provide a porous carbon material prepared based on a quenching-type deflagration method and its applications. This invention uses resin from waste circuit boards as a carbon source, rapidly creates pores through instantaneous deflagration, and utilizes a rapid quenching process to lock in highly active copper species, thereby obtaining a porous carbon material with high specific surface area and excellent catalytic activity.

[0007] Specifically, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for preparing porous carbon by a quenching-type deflagration method, comprising the following steps: Waste circuit boards are crushed and sieved to obtain circuit board powder, which is then placed in a sealed container. The tubular furnace is preheated to the set reaction temperature. The sealed container is then quickly pushed into the center of the furnace using a pull-out device to trigger an instantaneous deflagration reaction and maintain the reaction time. After the reaction is completed, the sealed container is immediately pulled out of the high-temperature zone of the tubular furnace using the pull-out device and placed in a room temperature environment for rapid cooling.

[0008] Preferably, the waste circuit board is a bare board without electronic components. After being crushed, it is passed through a 50-200 mesh sieve, and the resulting circuit board powder has a particle size of less than 100 mesh. Then, 5-20 g of the circuit board powder is weighed and placed in a sealed container for later use.

[0009] Preferably, the sealed container is selected from one of a covered ceramic boat or a sealed reaction vessel.

[0010] Preferably, the preset reaction temperature of the tubular furnace is 800~1200℃.

[0011] Preferably, the duration of the instantaneous deflagration reaction is 5 to 15 minutes.

[0012] Preferably, the pull-out device is a high-temperature resistant push rod or a slide rail with a tray, used to achieve rapid import and export of samples.

[0013] Preferably, the rapid cooling rate is greater than 200°C / min.

[0014] Preferably, the room temperature environment is an air environment, and the rapid cooling method includes placing it on refractory bricks or immersing it in a cooling medium.

[0015] In a second aspect, the present invention provides a porous carbon material, which is prepared by the method described in the first aspect.

[0016] Preferably, the porous carbon material is prepared in situ from waste circuit boards and contains highly active copper species that are locked by quenching, including elemental copper and / or cuprous oxide.

[0017] Preferably, the specific surface area of ​​the porous carbon material is ≥300 m². 2 / g, including micropores and mesopores, wherein the pore size of the micropores is ≤2.0 nm, the pore size of the mesopores is 2~50 nm, and the average pore size of the porous carbon material is 2~3 nm.

[0018] Preferably, the intensity ratio of the D peak to the G peak in the Raman spectrum of the porous carbon material is ≥1.10.

[0019] Preferably, the copper content in the porous carbon material is 12% to 16% by mass.

[0020] A third aspect of the present invention provides the application of the porous carbon material described in the second aspect in the catalytic degradation of pollutants.

[0021] The beneficial effects achieved by one or more of the above technical solutions of the present invention are as follows: (1) This invention utilizes the resin of waste circuit boards as a carbon source and metallic copper as an in-situ self-activating agent. Carbonization and activation are completed in one step through instantaneous deflagration combined with rapid quenching. There is no need to add additional chemical activators such as KOH and ZnCl2, which avoids the complex processes of using, recycling and washing activators, simplifies the process flow, and reduces production costs and the risk of secondary pollution. At the same time, this invention uses a tube furnace with a pull-out device to realize the rapid pushing in (1-3 seconds) and rapid pulling out (1-3 seconds) of the sample, ensuring the instantaneous deflagration reaction and the timeliness of the quenching process. It is easy to operate, highly controllable, and has good process reproducibility, making it suitable for industrial scale-up production.

[0022] (2) This invention rapidly "freezes" the highly reactive copper species (elemental copper and cuprous oxide) formed at high temperatures after the deflagration reaction through a quenching process (cooling rate > 200℃ / min), effectively preventing the copper species from being oxidized into low-reactivity copper oxide or agglomerated and sintered during slow cooling. Furthermore, this invention utilizes the non-equilibrium thermodynamic conditions of the quenching deflagration process to rapidly "freeze" supersaturated vacancies, lattice distortions, and grain boundary defects formed at high temperatures, forming a carbon skeleton rich in multi-level defects. Raman spectrum I of Example 1 D / I G The ratio is as high as 1.15, which is significantly higher than that of conventional pyrolysis processes (comparative example 3 is only 0.78), indicating that the number of defect sites in the carbon skeleton is significantly increased and the accessibility of defects is better than that of traditional methods. These defect sites themselves can serve as active centers for catalytic reactions, thereby significantly improving the catalytic performance of porous carbon.

[0023] (3) This invention achieves an instantaneous deflagration reaction by directly pushing the sample into a high-temperature zone (800~1200℃). The organic components in the circuit board decompose violently in a very short time, releasing a large amount of gas and forming abundant micropores and mesopores in the carbon matrix. As shown in Table 1, the specific surface area of ​​the porous carbon obtained in Example 1 is as high as 320.98 m². 2 / g, with an average pore size of 2.58 nm, significantly superior to conventional pyrolysis processes (comparative example 3 has a specific surface area of ​​only 124.79 m²). 2 / g, with an average pore size of 6.99 nm).

[0024] (4) The porous carbon material obtained in this invention exhibits excellent catalytic degradation performance for persistent organic pollutants. The porous carbon prepared in Example 1 achieved a removal rate of up to 92.70% for perfluorooctanoic acid (PFOA), which is significantly better than that of Comparative Example 1 (82.72%), Comparative Example 2 (75.94%), and Comparative Example 3 (63.12%). Furthermore, kinetic tests showed that the porous carbon material obtained in this invention could achieve a removal rate of approximately 83% within the first 10 minutes of the reaction, demonstrating rapid adsorption and catalytic degradation capabilities.

[0025] (5) The preparation process of this invention realizes the comprehensive utilization of resin and metallic copper in electronic waste, which is environmentally friendly and has high economic value.

[0026] This invention uses waste circuit boards as raw materials to achieve comprehensive utilization of resin and metallic copper in electronic waste. It requires no external chemicals, causes no secondary pollution, and conforms to the concepts of green chemistry and circular economy. Moreover, the raw materials used in this invention are waste circuit boards, which are widely available and inexpensive. The preparation process is simple, requires no external activators, and has low equipment requirements. The resulting product can be used as a high-performance catalyst in water treatment and other fields, and has good economic value and market prospects. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] Figure 1 This is a SEM image of the porous carbon material prepared in Example 1 of the present invention; Figure 2 This is a SEM image of the porous carbon material prepared in Comparative Example 1 of this invention. Figure 3 This is a SEM image of the porous carbon material prepared in Comparative Example 2 of this invention; Figure 4 This is a SEM image of the porous carbon material prepared in Comparative Example 3 of this invention. Figure 5 The image shows the EDS diagram of the porous carbon material prepared in Example 1 of this invention. Figure 6 XPS image of the porous carbon material prepared in Example 1 of this invention; Figure 7 This is a comparison diagram of the kinetics of PFOA degradation by porous carbon materials prepared in Example 1 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0029] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0030] A first typical embodiment of the present invention provides a method for preparing porous carbon by a quenching-type deflagration method, comprising the following steps: Waste circuit boards are crushed and sieved to obtain circuit board powder, which is then placed in a sealed container. The tubular furnace is preheated to the set reaction temperature. The sealed container is then quickly pushed into the center of the furnace using a pull-out device to trigger an instantaneous deflagration reaction and maintain the reaction time. After the reaction is completed, the sealed container is immediately pulled out of the high-temperature zone of the tubular furnace using the pull-out device and placed in a room temperature environment for rapid cooling.

[0031] In one or more embodiments of this implementation, the waste circuit board is a bare board without electronic components. After being crushed, it is passed through a 50-200 mesh sieve, and the resulting circuit board powder has a particle size of less than 100 mesh. Then, 5-20 g of the circuit board powder is weighed and placed in a sealed container for later use.

[0032] In one or more embodiments of this implementation, the sealed container is selected from a covered ceramic boat or a sealed reaction vessel.

[0033] In one or more embodiments of this implementation, the preset reaction temperature of the tubular furnace is 800~1200℃.

[0034] In one or more embodiments of this implementation, the time of the instantaneous deflagration reaction is 5 to 15 minutes.

[0035] In one or more embodiments of this implementation, the pull-out device is a high-temperature resistant push rod or a slide rail with a tray, used to achieve rapid import and export of samples.

[0036] In one or more embodiments of this implementation, the rapid cooling rate is greater than 200°C / min.

[0037] In one or more embodiments of this implementation, the room temperature environment is an air environment, and the rapid cooling method includes placing it on refractory bricks or immersing it in a cooling medium.

[0038] A second typical embodiment of the present invention provides a porous carbon material, which is prepared by the above method.

[0039] In one or more embodiments of this implementation, the porous carbon material is prepared in situ from waste circuit boards and contains highly active copper species that are locked by quenching, including elemental copper and / or cuprous oxide.

[0040] The term "locking" refers to the distribution pattern in which highly active copper species are coated or anchored by carbon layers in the porous carbon material.

[0041] In one or more embodiments of this implementation, the specific surface area of ​​the porous carbon material is ≥300 m². 2 / g, including micropores and mesopores, wherein the pore size of the micropores is ≤2.0 nm, the pore size of the mesopores is 2~50 nm, and the average pore size of the porous carbon material is 2~3 nm.

[0042] In one or more embodiments of this implementation, the intensity ratio of the D peak to the G peak in the Raman spectrum of the porous carbon material is ≥1.10.

[0043] In one or more embodiments of this implementation, the mass content of copper in the porous carbon material is 12% to 16%.

[0044] A third typical embodiment of the present invention provides an application of the above-mentioned porous carbon material in the catalytic degradation of pollutants.

[0045] In this invention, under high temperature, the epoxy resin and other organic components in the circuit board powder decompose violently as a carbon source to generate a large amount of gas, forming a rich porous structure in the carbon matrix; at the same time, the metallic copper in the circuit board powder acts as an in-situ self-activating agent and is reduced and activated under high temperature conditions and in the reducing atmosphere generated by the decomposition of organic matter.

[0046] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0047] Example 1: This example provides a porous carbon material prepared based on a quenching-type deflagration method. The specific preparation method is as follows: (1) The waste circuit boards after removing electronic components are cleaned to remove surface stains, dried to remove moisture, mechanically crushed and screened to obtain circuit board powder with a particle size of less than 100 mesh.

[0048] (2) Weigh 10 g of the above-mentioned circuit board powder and place it in a covered corundum ceramic boat, then cover it. Set the target temperature of the tube furnace to 1000℃. After the tube furnace reaches the set temperature and stabilizes, place the ceramic boat containing the sample on the pull-out device of the tube furnace. By pushing the pull-out device, quickly (within 1-3 seconds) send the ceramic boat into the center area of ​​the furnace. The sample undergoes an instantaneous deflagration reaction at high temperature, and this state is maintained for 10 minutes.

[0049] (3) After the deflagration reaction is completed, immediately (within 1 to 3 seconds) use the pulling device to quickly pull the ceramic boat from the center of the furnace to the furnace tube opening or completely remove it from the furnace, and quickly place it on the refractory bricks in room temperature air for rapid cooling (quenching). After cooling to room temperature, collect the black solid product, which is the porous carbon material.

[0050] Comparative Example 1: The difference between this comparative example and Example 1 is that in step (2), at room temperature, the corundum ceramic boat containing the raw materials is pushed into the tube furnace and slowly heated to 1000°C at a heating rate of 10°C / min, and maintained for 10 min. The content of other components and the preparation method are the same as in Example 1.

[0051] Comparative Example 2: The difference between this comparative example and Example 1 is that in step (3), after the reaction is completed, the sample is not quickly taken out and quenched, but is naturally cooled to room temperature in the tube furnace. The content of other components and the preparation method are the same as in Example 1.

[0052] Comparative Example 3: The difference between this comparative example and Example 1 is that: at the initial room temperature, the corundum ceramic boat containing the raw materials was pushed into the tube furnace and slowly heated to 1000°C. After the reaction was completed, the sample was not quickly taken out for quenching, but was allowed to cool naturally to room temperature in the tube furnace. The content of other components and the preparation method were the same as in Example 1.

[0053] Experimental Example 1: In this experimental example, the structure of the porous carbon materials prepared in Example 1 and Comparative Examples 1-3 was determined. like Figure 1 As shown, the active copper species that were immobilized in situ were widely distributed on the surface of Example 1, while no active copper species were widely distributed in any of the comparative examples (such as...). Figures 2-4 (As shown).

[0054] like Figure 5 As shown in the EDS diagram, copper is uniformly distributed on the surface of the porous carbon material without obvious agglomeration. This indicates that after the instantaneous deflagration combined with rapid quenching process, the copper in the circuit board is successfully and uniformly dispersed in the carbon skeleton at the nanoscale, rather than sintered into large copper particles.

[0055] like Figure 6 As shown in the XPS image, copper in the porous carbon material prepared in the embodiments of this application mainly exists in the form of elemental copper (Cu). 0 ) and cuprous oxide (Cu + It exists in the form of ).

[0056] As shown in Table 1, the yield, specific surface area, pore size, copper content, and defect density of the porous carbon material were tested, as detailed below: The yield of porous carbon materials was calculated by dividing the mass of the prepared porous carbon by the mass of the circuit board powder raw material. Specific surface area and average pore size were tested using a Micron ASAP2420. The surface metal Cu content of the materials in Examples 1 and Comparative Examples 1-3 was determined by EDS. The intensity ratio (Ig) of the D peak to the G peak of the materials in Examples 1 and Comparative Examples 1-3 was determined by Raman spectroscopy. D / I G The defect density test was conducted, and the specific test data is shown in Table 1. Table 1

[0057] Comparing Example 1 and Comparative Example 1, it was found that: Comparative Example 1, using room temperature loading and slow heating to 1000°C, did not experience instantaneous deflagration. The pyrolysis of the raw materials was mild, and gas release was slow, making it difficult to form a severe pore-forming effect. Therefore, Comparative Example 1 had a lower specific surface area, and the development of micropores and mesopores was significantly weaker than that of Example 1. At the same time, the thermodynamic conditions during the slow pyrolysis process were relatively balanced, resulting in fewer carbon framework defects, a more regular lattice, and a significantly lower defect density and number of active sites compared to Example 1.

[0058] Comparing Example 1 and Comparative Example 2, it was found that although Comparative Example 2 achieved high-temperature rapid feeding and instantaneous deflagration, resulting in a relatively well-developed pore structure, it employed natural cooling with the furnace after the reaction without quenching. Defects such as supersaturated vacancies and lattice distortion formed at high temperatures underwent structural relaxation and repair during slow cooling, leading to a significant decrease in defect density. Simultaneously, during natural cooling, copper species were easily oxidized by air and agglomerated, resulting in a significant loss of highly active copper sites and weaker catalytic activity compared to Example 1.

[0059] Comparing Example 1 and Comparative Example 3, it was found that Comparative Example 3, using a traditional slow heating method combined with natural cooling, exhibited neither instantaneous deflagration nor quenching locking effects, resulting in a mild and balanced pyrolysis process. The carbon skeleton showed a high degree of graphitization and few defect sites, with a significantly lower number of active sites compared to Example 1. Furthermore, the copper species were fully oxidized and agglomerated under prolonged high temperature and slow cooling, making it almost impossible to retain highly active metallic copper. Therefore, its overall performance was significantly inferior to Example 1.

[0060] Experimental Example 1: This experimental example tests the pollutant degradation effect of the porous carbon materials prepared in the examples and comparative examples. The porous carbon materials prepared in Example 1 and Comparative Examples 1-3 were used to test the catalytic degradation performance of perfluorooctanoic acid (PFOA). The specific methods and results are as follows: A simulated PFOA wastewater with an initial concentration of 50 mg / L was prepared, and porous carbon from Example 1 and each comparative example was added at a dosage of 1 g / L. The solution was then shaken in a water bath for 8 h under normal temperature and pressure conditions and protected from light. After filtration through a filter membrane, the concentration of PFOA in the solution was determined by high performance liquid chromatography-tandem mass spectrometry, and the removal rate of each component was calculated. The calculation results are shown in Table 2.

[0061] The formula for calculating PFOA removal rate is:

[0062] Where C0 is the initial concentration of PFOA (mg / L); C t Let t be the residual concentration of PFOA (mg / L).

[0063] Table 2

[0064] Analysis of the data in Table 2 shows that the removal rates of PFOA in Comparative Examples 1-3 were all lower than those in Example 1, with Example 1 exhibiting the best removal effect. This indicates that the porous carbon material prepared by the present invention through a combination of instantaneous deflagration and quenching processes demonstrates excellent catalytic degradation performance against persistent organic pollutants PFOA due to its high specific surface area, abundant pore structure, high-density carbon skeleton defects, and highly active copper species locked by quenching.

[0065] Based on this, a kinetic degradation test was conducted on Example 1. The specific methods and results are as follows: PFOA-simulated wastewater with an initial concentration of 50 mg / L was prepared, and PFOA was added to Examples 1 and Comparative Examples 1-3 at a dosage of 1 g / L. The mixture was stirred in the dark on a magnetic stirrer under normal temperature and pressure. Samples were filtered and taken at 1, 3, 5, 7, 10, 15, 20, 30, 45, 60, 90, 120, 180, and 240 min to determine the PFOA concentration and calculate the removal amount.

[0066] The results are as follows Figure 7 As shown in Table 3: Table 3

[0067] Analysis of the table data reveals that the porous carbon material prepared by the instantaneous deflagration combined with quenching process in the embodiments of the present invention exhibits superior performance in degrading pollutants, and the degradation rate is significantly higher than that of the comparative example.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing porous carbon by quenching-type deflagration, characterized in that, Includes the following steps: Waste circuit boards are crushed and sieved to obtain circuit board powder, which is then placed in a sealed container. The tubular furnace is preheated to the set reaction temperature. The sealed container is then quickly pushed into the center of the furnace using a pull-out device to trigger an instantaneous deflagration reaction and maintain the reaction time. After the reaction is completed, the sealed container is immediately pulled out of the high-temperature zone of the tubular furnace using the pull-out device and placed in a room temperature environment for rapid cooling.

2. The method as described in claim 1, characterized in that, The waste circuit board is a bare board without electronic components. After being crushed, it is passed through a 50-200 mesh sieve. The resulting circuit board powder has a particle size of less than 100 mesh. Then, 5-20 g of the circuit board powder is weighed and placed in a sealed container for later use. Preferably, the sealed container is selected from one of a covered ceramic boat or a sealed reaction vessel.

3. The method as described in claim 1, characterized in that, The preset reaction temperature of the tubular furnace is 800~1200℃; Preferably, the instantaneous deflagration reaction takes 5 to 15 minutes, and the rapid cooling rate is greater than 200°C / min.

4. The method as described in claim 1, characterized in that, The pull-out device is a high-temperature resistant push rod or a slide rail with a tray, used to enable rapid import and export of samples.

5. The method as described in claim 1, characterized in that, The room temperature environment is an air environment, and the rapid cooling method includes placing it on refractory bricks or immersing it in a cooling medium.

6. A porous carbon material, characterized in that, It is prepared by the method described in any one of claims 1 to 5.

7. The porous carbon material as described in claim 6, characterized in that, The porous carbon material is prepared in situ from waste circuit boards and contains highly active copper species that are locked by quenching. The highly active copper species include elemental copper and / or cuprous oxide.

8. The porous carbon material as described in claim 6, characterized in that, The specific surface area of ​​the porous carbon material is ≥300 m². 2 / g, including micropores and mesopores, wherein the pore size of the micropores is ≤2.0 nm, the pore size of the mesopores is 2~50 nm, and the average pore size of the porous carbon material is 2~3 nm.

9. The porous carbon material as described in claim 6, characterized in that, The intensity ratio of the D peak to the G peak in the Raman spectrum of the porous carbon material is ≥1.10; Preferably, the copper content in the porous carbon material is 12% to 16% by mass.

10. The application of the porous carbon material according to any one of claims 6 to 9 in the catalytic degradation of pollutants.

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