A method for preparing a catalyst by using a waste lithium ion battery separator, the catalyst and application thereof

Abstract

This invention discloses a method for preparing a catalyst using waste lithium-ion battery separators, the catalyst itself, and its application. The method involves coating the surface of the waste battery separator with several metal salts in a specific ratio to obtain a pyrolysis precursor. This precursor is then carbonized in an inert atmosphere to obtain a carbon-based metal catalyst. Carbon-based metal catalysts are among the most commonly used industrial catalysts and can be used to efficiently catalyze CO2 conversion reactions to generate CO, an important chemical raw material. This invention, by introducing the auxiliary role of metals, enables the pyrolysis of waste lithium-ion battery separators into carbon materials, directly converting them into industrially used carbon-based metal catalysts, which are then applied to the catalytic reaction of CO2 to CO.

Description

Technical Field

[0001] This invention belongs to the field of waste lithium-ion battery separator recycling, and relates to a method for preparing catalysts using waste lithium-ion battery separators, the catalysts, and their applications. Background Technology

[0002] In 2021, the lithium-ion battery industry boomed. Currently, a massive number of waste lithium batteries are generated annually. Researchers are primarily focused on recycling the positive and negative electrode materials of these batteries, with limited research on the recycling of waste separators. The separators in lithium-ion batteries are mainly composed of synthetic plastics such as polyethylene (PE) and polypropylene (PP). Direct landfill disposal would take two to three hundred years for natural degradation, causing severe environmental pollution. Incineration is currently the most widely used, cheapest, and simplest method of plastic recycling, and the heat generated can be used for power generation. However, during incineration, the polymer plastics cannot be effectively recycled, inevitably leading to resource waste and environmental pollution. To date, there have been reports of recycling lithium battery separators using physical scrubbing, diluent cleaning, high-temperature decomposition, and inorganic reagent methods, but these methods suffer from high costs and incomplete cleaning. Patent CN106299532A discloses a method for recycling lithium battery ceramic separators. The method involves first completely releasing the residual charge from the discarded batteries, then sequentially disassembling the casing, crushing the battery electrode rolls, adding flotation reagents for flotation separation, calcination and washing, adding acid and alkaline solutions to precipitate aluminum hydroxide, and heating to obtain inorganic γ-alumina powder. This method is relatively complex and can only be applied to lithium battery ceramic separators; the treatment of PE and PP separators for lithium batteries remains a challenging problem. Pyrolysis of plastics such as PE and PP is a preferred method for generating carbon materials. However, direct pyrolysis will cause the main chain to break down, generating light alkanes and some low molecular weight liquid oils, which cannot yield high-value carbon materials [López A., de Marco I., Caballero BM, Laresgoiti MF, Adrados A., Aranzabal A. Catalyticpyrolysis of plastic wastes with two different types of catalysts: ZSM-5zeolite and Red Mud[J]. Appl. Catal. B: Environ. 2011, 104, 3–4: 211-219.].

[0003] In recent years, carbon-based metal catalysts have been widely used in both basic research and industrial production. Introducing metals for protection during pyrolysis can inhibit the thermal decomposition of the main chain of plastic molecules, thereby achieving plastic carbonization [Chernozatonskii LA, Kukovitskii EF, Musatov AL, Ormont A. B., Izraeliants KR, L'Vov SG Carbon crooked nanotube layers of polyethylene: Synthesis, structure and electron emission[J]. Carbon. 1998, 36,5-6: 713-715.]. Meanwhile, during the carbonization of plastics, the metal precursor is transformed into fine metal or metal oxide nanoparticles, thus obtaining carbon-based composite materials of metal or metal oxides, which can be directly used for catalytic reactions [Tang T.,Chen XC, Meng XY, Chen H., Ding YPSynthesis of multiwalled carbon nanotubes by catalytic combustion of polypropylene[J]. Angewandte Chemie-International Edition. 2005, 44, 10: 1517-1520.].

[0004] Therefore, inventing a method for preparing catalysts using waste lithium-ion battery separators, the catalysts themselves, and their applications is crucial for achieving the effective utilization of resources. Summary of the Invention

[0005] This invention proposes a method for preparing a catalyst using waste lithium-ion battery separators, the catalyst itself, and its application. This solves the environmental pollution problem caused by direct landfilling of waste lithium batteries or direct incineration of lithium battery separators. Several metal salts are coated on the surface of the waste battery separator in a certain proportion to obtain a pyrolysis precursor. The pyrolysis precursor is then carbonized in an inert atmosphere to obtain a carbon-based metal catalyst. This carbon-based metal catalyst is directly used to catalyze the CO2 conversion reaction, eliminating carbon components while generating CO as a chemical raw material.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] As a first aspect of the present invention, a method for preparing a catalyst from the waste ion exchange membrane is provided, comprising the following steps: preparing a slurry of 0.05-0.2 g / mL using ethanol as a solvent; uniformly spraying the slurry onto the cleaned surface of a waste lithium battery polypropylene membrane using a spray bottle; drying the membrane to ensure that the mass ratio of the coated metal acetylacetone salt to the membrane is 1:4-6, serving as a pyrolysis precursor; and then subjecting the pyrolysis precursor to an argon or nitrogen atmosphere at a flow rate of 5-30 sccm at 550-650 °C. o Carbon-based metal catalysts were prepared by carbonization at C for 1-2 hours.

[0008] The slurry used in the above steps is one or more of zirconium acetylacetonate, iron acetylacetonate, nickel acetylacetonate, copper acetylacetonate, and magnesium acetylacetonate.

[0009] As a second aspect of the invention, the invention claims protection for a carbon-based metal catalyst with a carbonization rate of 1.56-21.8%.

[0010] As a third aspect of the invention, this application also provides the application of carbon-based metal catalysts in CO2 conversion reactions. The application method includes the following steps: calculating the membrane carbonization rate for pyrolysis assisted by different acetylacetone metal salts using thermogravimetric data; placing a catalyst with a carbonization rate ranging from 13.6% to 21.8% in a reactor; purging the reactor with argon gas at a flow rate of 10-30 sccm to remove air; then purging with CO2 at a flow rate of 20-30 sccm before starting the heating process. The reaction temperature range is 30-900°C. o C, heating rate is 20 o C / min. The gaseous products of the reaction process are automatically injected into the mass spectrometer for analysis.

[0011] The present invention has the following beneficial effects:

[0012] 1. This invention successfully converts easily thermally decomposed waste polypropylene membranes into carbon materials through metal assistance, directly obtaining practically usable carbon-based metal catalysts, thus protecting the environment while achieving the rational utilization of waste battery resources.

[0013] 2. This invention calculates the carbonization rate of the diaphragm using thermogravimetric data and applies this calculation to CO product generation. It was found that zirconium, when used to assist in the pyrolysis of waste polypropylene diaphragms to convert them into carbon materials, achieves the highest carbonization rate. The obtained ZrO2 / C catalyst exhibits significant weight loss at approximately 450°C under a CO2 atmosphere, accompanied by CO gas generation, indicating its applicability in the CO2+C to CO reaction. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 The thermogravimetric curves of the embodiments of the present invention and Comparative Example 1 under an argon atmosphere are shown.

[0016] Figure 2 The images are TEM images of the ZrO2 / C sample prepared in Example 1 of this invention at 100 nm and 5 nm scales, where (a) is at 100 nm scale and (b) is at 5 nm scale.

[0017] Figure 3 The image shows the XRD pattern of the ZrO2 / C sample prepared in Example 1 of this invention.

[0018] Figure 4 The thermogravimetric curve of the ZrO2 / C sample prepared in Example 1 of this invention under CO2 atmosphere.

[0019] Figure 5 The mass spectrometry response curve of CO in the gaseous products of the ZrO2 / C sample prepared in Example 1 of this invention under a CO2 atmosphere.

[0020] Figure 6 The images are TEM images of the ZrO2 sample prepared in Example 1 of this invention at 100 nm and 20 nm scales, where (a) is at 100 nm scale and (b) is at 20 nm scale.

[0021] Figure 7 The thermogravimetric curve of the Fe2O3 / C sample prepared in Example 2 of this invention under CO2 atmosphere.

[0022] Figure 8 The mass spectrometry response curve of CO in the gaseous products of the Fe2O3 / C sample prepared in Example 2 of this invention under a CO2 atmosphere. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1

[0025] This embodiment describes a method and application for preparing a catalyst using Zr-assisted waste lithium-ion battery separators. The steps are as follows:

[0026] A 0.1 g / mL Zr(acac)₄ solution was prepared using ethanol as a solvent and used as a slurry. The slurry was then evenly sprayed onto the surface of 500 mg of cleaned waste membrane using a spray bottle. After drying, the membrane was weighed to ensure a Zr(acac)₄ to membrane mass ratio of 1:5, yielding a Zr(acac)₄ / PP pyrolysis precursor. The carbonization precursor was placed in a tube furnace and heated at 550 °C under an argon atmosphere at a flow rate of 10 sccm. o Carbonization with C for 2 hours, followed by cooling, yields a ZrO2 / C catalyst. Figure 1 The thermogravimetric curves under an argon atmosphere show that, with the assistance of Zr(acac)4, the carbonization rate of the membrane is 21.8%.

[0027] The ZrO2 / C sample prepared in this embodiment was tested by transmission electron microscopy as follows: Figure 2 As shown, by Figure 2 It can be seen that the surface morphology is characterized by ZrO2 particles with a size of 5-10 nm uniformly dispersed on the surface of amorphous carbon. Furthermore, the ZrO2 / C sample prepared in this embodiment contains only diffraction peaks of ZrO2 (PDF#49-1642) and amorphous carbon, confirming its material composition and crystal structure. The results are as follows... Figure 3 As shown.

[0028] 50 mg of the ZrO2 / C catalyst prepared in this embodiment was weighed and placed in the quartz tube of the fixed-bed reactor. The tube was first purged with argon gas at a flow rate of 20 sccm for 30 min to remove air, then switched to CO2 gas and purged again at a flow rate of 20 sccm. The reaction temperature range was set to 30-900 °C. o C, heating rate is 20 o C / min. The gaseous products from the reaction process are automatically introduced into the mass spectrometer for analysis.

[0029] The test results are as follows: Figure 4 and Figure 5 As shown, the ZrO2 / C catalyst at approximately 450 o The carbon component in ZrO2 / C began to show significant weight loss, and CO gas was detected by mass spectrometry, indicating that the carbon component in ZrO2 / C underwent the reaction CO2+C→2CO with CO2.

[0030] After completely eliminating the carbon component in ZrO2 / C by reacting with CO2, a ZrO2 sample was obtained, the surface morphology of which is as follows: Figure 6 As shown, ZrO2 nanoparticles grow to a size of approximately 30 nm and interconnect to form a framework structure.

[0031] Example 2

[0032] This embodiment describes a method and application for preparing a catalyst using Fe metal-assisted waste lithium-ion battery separators. The steps are as follows:

[0033] A 0.1 g / mL Fe(acac)3 solution was prepared using ethanol as a solvent and used as a slurry. The slurry was then evenly sprayed onto the surface of 500 mg of cleaned waste membrane using a spray bottle. After drying, the membrane was weighed to ensure a Fe(acac)3 to membrane mass ratio of 1:5, yielding Fe(acac)3 / PP as a pyrolysis precursor. The carbonization precursor was placed in a tube furnace and heated at 550 °C under an argon atmosphere at a flow rate of 10 sccm. o Carbonization with C for 2 hours, followed by cooling, yielded an Fe₂O₃ / C catalyst. Figure 1 The thermogravimetric curves under an argon atmosphere show that, with the assistance of Fe(acac)3, the carbonization rate of the membrane is 13.6%.

[0034] 50 mg of the Fe₂O₃ / C catalyst prepared in this embodiment was weighed and placed in the quartz tube of the fixed-bed reactor. The tube was first purged with argon gas at a flow rate of 20 sccm for 30 min to remove air, then switched to CO₂ gas and purged again at a flow rate of 20 sccm. The reaction temperature range was set to 30-900 °C. o C, heating rate is 20 o C / min. The gaseous products from the reaction process are automatically introduced into the mass spectrometer for analysis.

[0035] The test results are as follows: Figure 7 and Figure 8 As shown, the Fe2O3 / C catalyst, under a CO2 atmosphere, has a temperature of nearly 800°C. o Significant weight loss only begins after C, accompanied by the production of CO gas. In comparison, it was found that the Fe2O3 / C catalyst's promoting effect on the CO2+C→2CO reaction was far less than that of ZrO2 / C in Example 1.

[0036] Example 3

[0037] This embodiment describes a method for preparing a catalyst using Ni-metallic assisted waste lithium-ion battery separators. The steps are as follows:

[0038] A 0.1 g / mL Ni(acac)₂ solution was prepared using ethanol as a solvent and used as a slurry. The slurry was then evenly sprayed onto the surface of 500 mg of cleaned waste membrane using a spray bottle. After drying, the membrane was weighed to ensure a Ni(acac)₂ to membrane mass ratio of 1:5, yielding Ni(acac)₂ / PP as a pyrolysis precursor. The carbonization precursor was placed in a tube furnace and heated at 550 °C under an argon atmosphere at a flow rate of 10 sccm. o Carbonization with C for 2 hours, followed by cooling, yields a NiO / C catalyst. Figure 1The thermogravimetric curves under an argon atmosphere show that the carbonization rate of the membrane is 1.56% with the assistance of Ni(acac)2.

[0039] Because the carbonization rate of the membrane is too low with the assistance of Ni(acac)2, the performance test of the NiO / C catalyst for the conversion of CO2 to CO is not carried out.

[0040] Example 4

[0041] This embodiment describes a method for preparing a catalyst using Cu metal-assisted spent lithium-ion battery separators. The steps are as follows:

[0042] A 0.1 g / mL Cu(acac)₂ solution was prepared using ethanol as a solvent and used as a slurry. The slurry was then evenly sprayed onto the surface of 500 mg of cleaned waste membrane using a spray bottle. After drying, the membrane was weighed to ensure a Cu(acac)₂ to membrane mass ratio of 1:5, yielding a Cu(acac)₂ / PP pyrolysis precursor. The carbonization precursor was placed in a tube furnace and heated at 550 °C under an argon atmosphere at a flow rate of 10 sccm. o Carbonization with C for 2 hours, followed by cooling, yields a CuO / C catalyst. Figure 1 The thermogravimetric curves under an argon atmosphere show that, with the assistance of Cu(acac)2, the carbonization rate of the membrane is 2.09%.

[0043] Because the carbonization rate of the membrane is too low with the assistance of Cu(acac)2, the performance test of CuO / C catalyst on the conversion of CO2 to CO is not carried out.

[0044] Example 5

[0045] This embodiment describes a method for preparing a catalyst using magnesium metal-assisted spent lithium-ion battery separators. The steps are as follows:

[0046] A 0.1 g / mL Mg(acac)₂ solution was prepared using ethanol as a solvent and used as a slurry. The slurry was then evenly sprayed onto the surface of 500 mg of cleaned waste diaphragm using a spray bottle. After drying, the slurry was weighed to ensure a Mg(acac)₂ to diaphragm mass ratio of 1:5, yielding Mg(acac)₂ / PP as a pyrolysis precursor. The carbonization precursor was placed in a tube furnace and heated at 550 °C under an argon atmosphere at a flow rate of 10 sccm. o Carbonization with C for 2 hours, followed by cooling, yielded an MgO / C catalyst. Figure 1 The thermogravimetric curves under an argon atmosphere show that the carbonization rate of the membrane is 3.17% with the assistance of Mg(acac)2.

[0047] Because the carbonization rate of the membrane is too low with the assistance of Mg(acac)2, the performance test of the MgO / C catalyst for the conversion of CO2 to CO is not carried out.

[0048] Example 6

[0049] This embodiment describes a method and application for preparing a catalyst using Zr-assisted waste lithium-ion battery separators. The steps are as follows:

[0050] A 0.05 g / mL Zr(acac)₄ solution was prepared using ethanol as a solvent and used as a slurry. The slurry was then evenly sprayed onto the surface of 500 mg of cleaned waste membrane using a spray bottle. After drying, the membrane was weighed to ensure a Zr(acac)₄ to membrane mass ratio of 1:4, yielding a Zr(acac)₄ / PP pyrolysis precursor. The carbonization precursor was placed in a tube furnace and heated at 650 °C under a nitrogen atmosphere at a flow rate of 5 sccm. o Carbonization with C for 1 hour, followed by cooling, yields a ZrO2 / C catalyst. Figure 1 The thermogravimetric curves under an argon atmosphere show that, with the assistance of Zr(acac)4, the carbonization rate of the membrane is 21.8%.

[0051] 50 mg of the ZrO2 / C catalyst prepared in this embodiment was weighed and placed in the quartz tube of the fixed-bed reactor. The tube was first purged with argon gas at a flow rate of 10 sccm for 30 min to remove air, then switched to CO2 gas and purged at a flow rate of 30 sccm. The reaction temperature range was set to 30-900 °C. o C, heating rate is 20 o C / min. The gaseous products from the reaction process are automatically introduced into the mass spectrometer for analysis.

[0052] The test results are as follows: Figure 4 and Figure 5 As shown, the ZrO2 / C catalyst at approximately 450 o The carbon component in ZrO2 / C began to show significant weight loss, and CO gas was detected by mass spectrometry, indicating that the carbon component in ZrO2 / C underwent the reaction CO2+C→2CO with CO2.

[0053] Example 7

[0054] This embodiment describes a method and application for preparing a catalyst using Zr-assisted waste lithium-ion battery separators. The steps are as follows:

[0055] A 0.05 g / mL Zr(acac)₄ solution was prepared using ethanol as a solvent to form a slurry. This slurry was then evenly sprayed onto the surface of 500 mg of cleaned waste membrane using a spray bottle. After drying, the membrane was weighed to ensure a Zr(acac)₄ to membrane mass ratio of 1:6, yielding a Zr(acac)₄ / PP pyrolysis precursor. The carbonization precursor was placed in a tube furnace and heated at 650 °C under a nitrogen atmosphere at a flow rate of 5 sccm. o Carbonization with C for 1 hour, followed by cooling, yields a ZrO2 / C catalyst. Figure 1The thermogravimetric curves under an argon atmosphere show that, with the assistance of Zr(acac)4, the carbonization rate of the membrane is 21.8%.

[0056] 50 mg of the ZrO2 / C catalyst prepared in this embodiment was weighed and placed in the quartz tube of the fixed-bed reactor. The tube was first purged with argon gas at a flow rate of 10 sccm for 30 min to remove air, then switched to CO2 gas and purged at a flow rate of 20 sccm. The reaction temperature range was set to 30-900 °C. o C, heating rate is 20 o C / min. The gaseous products from the reaction process are automatically introduced into the mass spectrometer for analysis.

[0057] The test results are as follows: Figure 4 and Figure 5 As shown, the ZrO2 / C catalyst at approximately 450 o The carbon component in ZrO2 / C began to show significant weight loss, and CO gas was detected by mass spectrometry, indicating that the carbon component in ZrO2 / C underwent the reaction CO2+C→2CO with CO2.

[0058] Example 8

[0059] This embodiment describes a method and application for preparing a catalyst using Zr-assisted waste lithium-ion battery separators. The steps are as follows:

[0060] A 0.2 g / mL Zr(acac)₄ solution was prepared using ethanol as a solvent and used as a slurry. The slurry was then evenly sprayed onto the surface of 500 mg of cleaned waste membrane using a spray bottle. After drying, the membrane was weighed to ensure a Zr(acac)₄ to membrane mass ratio of 1:6, yielding a Zr(acac)₄ / PP pyrolysis precursor. The carbonization precursor was placed in a tube furnace and heated at 600 °C under a nitrogen atmosphere at a flow rate of 30 sccm. o Carbonization of C for 1.5 hours, followed by cooling, yields a ZrO2 / C catalyst. Figure 1 The thermogravimetric curves under an argon atmosphere show that, with the assistance of Zr(acac)4, the carbonization rate of the membrane is 21.8%.

[0061] 50 mg of the ZrO2 / C catalyst prepared in this embodiment was weighed and placed in the quartz tube of the fixed-bed reactor. The tube was first purged with argon gas at a flow rate of 30 sccm for 30 min to remove air, then switched to CO2 gas and purged at a flow rate of 25 sccm. The reaction temperature range was set to 30-900 °C. o C, heating rate is 20 o C / min. The gaseous products from the reaction process are automatically introduced into the mass spectrometer for analysis.

[0062] The test results are as follows: Figure 4 and Figure 5 As shown, the ZrO2 / C catalyst at approximately 450 o The carbon component in ZrO2 / C began to show significant weight loss, and CO gas was detected by mass spectrometry, indicating that the carbon component in ZrO2 / C underwent the reaction CO2+C→2CO with CO2.

[0063] Example 9

[0064] This embodiment describes a method for preparing a catalyst using Ni-metallic assisted waste lithium-ion battery separators. The steps are as follows:

[0065] A 0.05 g / mL Ni(acac)₂ solution was prepared using ethanol as a solvent and used as a slurry. The slurry was then evenly sprayed onto the surface of 500 mg of cleaned waste membrane using a spray bottle. After drying, the membrane was weighed to ensure a Ni(acac)₂ to membrane mass ratio of 1:5, yielding Ni(acac)₂ / PP as a pyrolysis precursor. The carbonization precursor was placed in a tube furnace and heated at 550 °C under an argon atmosphere at a flow rate of 20 sccm. o Carbonization with C for 1 hour, followed by cooling, yields a NiO / C catalyst. Figure 1 The thermogravimetric curves under an argon atmosphere show that the carbonization rate of the membrane is 1.56% with the assistance of Ni(acac)2.

[0066] Because the carbonization rate of the membrane is too low with the assistance of Ni(acac)2, the performance test of the NiO / C catalyst for the conversion of CO2 to CO is not carried out.

[0067] Example 10

[0068] This embodiment describes a method for preparing a catalyst using Cu metal-assisted spent lithium-ion battery separators. The steps are as follows:

[0069] A 0.2 g / mL Cu(acac)₂ solution was prepared using ethanol as a solvent and used as a slurry. The slurry was then evenly sprayed onto the surface of 500 mg of cleaned waste membrane using a spray bottle. After drying, the membrane was weighed to ensure a Cu(acac)₂ to membrane mass ratio of 1:5, yielding a Cu(acac)₂ / PP pyrolysis precursor. The carbonization precursor was placed in a tube furnace and heated at 600 °C under a nitrogen atmosphere at a flow rate of 5 sccm. o Carbonization with C for 2 hours, followed by cooling, yields a CuO / C catalyst. Figure 1 The thermogravimetric curves under an argon atmosphere show that, with the assistance of Cu(acac)2, the carbonization rate of the membrane is 2.09%.

[0070] Because the carbonization rate of the membrane is too low with the assistance of Cu(acac)2, the performance test of CuO / C catalyst on the conversion of CO2 to CO is not carried out.

[0071] Example 11

[0072] This embodiment describes a method for preparing a catalyst using magnesium metal-assisted spent lithium-ion battery separators. The steps are as follows:

[0073] A 0.1 g / mL Mg(acac)₂ solution was prepared using ethanol as a solvent and used as a slurry. The slurry was then evenly sprayed onto the surface of 500 mg of cleaned waste diaphragm using a spray bottle. After drying, the slurry was weighed to ensure a Mg(acac)₂ to diaphragm mass ratio of 1:4, yielding Mg(acac)₂ / PP as a pyrolysis precursor. The carbonization precursor was placed in a tube furnace and heated at 550 °C under a nitrogen atmosphere at a flow rate of 30 sccm. o Carbonization with C for 1 hour, followed by cooling, yields an MgO / C catalyst. Figure 1 The thermogravimetric curves under an argon atmosphere show that the carbonization rate of the membrane is 3.17% with the assistance of Mg(acac)2.

[0074] Because the carbonization rate of the membrane is too low with the assistance of Mg(acac)2, the performance test of the MgO / C catalyst for the conversion of CO2 to CO is not carried out.

[0075] Comparative Example 1

[0076] 500 mg of washed waste diaphragm was used directly as a carbonization precursor and placed in a tube furnace under an argon atmosphere at a flow rate of 10 sccm. o Carbonization with C for 2 hours, followed by cooling, yields the carbon product. Figure 1 The thermogravimetric curves of Comparative Example 1 under an argon atmosphere show that the carbonization rate of the diaphragm is only 0.28% without metal assistance.

[0077] Therefore, without metal assistance, the carbon product obtained by direct pyrolysis of the diaphragm is extremely rare, so the performance of this carbon product in the CO2 to CO conversion reaction is not tested.

[0078] As can be seen from the thermogravimetric curves of the examples and Comparative Example 1, metals all have the effect of assisting carbonization of polypropylene membranes. Among them, Zr has the best effect in assisting carbonization, and the prepared ZrO2 / C catalyst has the best catalytic effect on the reaction CO2+C→2CO.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. Use of a carbon-based metal catalyst in the catalytic conversion of CO2 into CO, characterized in that, The preparation steps of the carbon-based metal catalyst are as follows: (1) The slurry is mixed and coated onto the surface of the waste lithium-ion battery separator, and then dried to obtain the pyrolysis precursor; (2) The pyrolysis precursor of step (1) is carbonized and cooled in an inert atmosphere to obtain the catalyst; In step (1), the slurry is an ethanol solution of a metal salt, and the concentration of the metal salt in the slurry is 0.05-0.2 g / mL; The metal salt is selected from one or more of zirconium acetylacetonate and iron acetylacetonate; In step (1), the waste lithium-ion battery separator is composed of polypropylene, and the mass ratio of the coated metal acetylacetone salt to the waste lithium-ion battery separator is 1:4-6. The carbonization rate of the carbon-based metal catalyst is 13.6%-21.8%.

2. Use of the carbon-based metal catalyst according to claim 1 for catalyzing the conversion of CO2 into CO, characterized in that: In step (2), the inert atmosphere is argon or nitrogen, the flow rate is 5-30 sccm, the carbonization temperature is 550-650℃, and the carbonization time is 1-2 hours.

3. Use of the carbon-based metal catalyst according to claim 1 in the catalytic conversion of CO2 into CO, characterized in that, The application includes the following steps: placing the catalyst in a reactor, first purging the reactor with inert gas to remove the air, and then introducing CO2 to carry out the catalytic reaction.

4. The application of the carbon-based metal catalyst according to claim 3 in the catalytic conversion of CO2 to CO, characterized in that: The inert gas is argon, the argon purging flow rate is 10-30 sccm, and the CO2 introduction flow rate is 20-30 sccm.

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