NiCoMnOx catalyst based on waste lithium ion battery and application of NiCoMnOx catalyst in catalytic oxidation of VOCs

Abstract

The invention provides a NiCoMnOx catalyst based on a waste lithium ion battery and application of the NiCoMnOx catalyst in catalytic oxidation of VOCs (Volatile Organic Compounds). A waste nickel-cobalt-manganese ternary material lithium ion battery is used as a raw material, a precursor material rich in Ni, Co and Mn is obtained through pyrogenic process treatment, and the nitrogen-doped NiCoMnOx catalyst is prepared through nitrogen source auxiliary heat treatment on the basis. The obtained catalyst has a stable composite oxide structure and good oxygen migration ability, and can be used for the catalytic oxidation reaction of VOCs, especially toluene. Compared with a traditional chemical synthesis catalyst, the method realizes functional utilization of valuable components in the waste lithium ion battery, and has the advantages of simplified process, high recycling degree, environmental friendliness and the like.

Description

Technical Field

[0001] This invention belongs to the field of electronic solid waste treatment and VOCs control technology, specifically relating to a NiCoMnO based on waste lithium-ion batteries. x Catalysts and their application in the catalytic oxidation of VOCs. Background Technology

[0002] Entering the 21st century, resource scarcity and environmental degradation have become common global challenges, with air pollution gradually emerging as the primary issue to address. In recent years, non-carbon dioxide emissions have grown faster than carbon dioxide emissions. Among these, VOCs are considered important precursors to secondary organic aerosols (SOA) and tropospheric ozone (O3), and are significant factors contributing to the formation of peroxyacetyl nitrate (PAN) and photochemical smog. In current air pollution control efforts, these pollution sources have severely impacted air quality levels. The photochemical reactions they trigger significantly enhance the greenhouse effect, and due to their high solubility and mobility, they are gradually causing damage to groundwater and tap water. VOC emissions not only severely pollute the atmospheric environment but also harm human health, causing respiratory infections, damage to the blood system, and diseases such as cancer. Therefore, controlling VOC emissions is crucial and holds significant strategic importance for China's current air pollution prevention and control efforts.

[0003] VOCs control strategies mainly include source reduction, process control, and end-of-pipe treatment technologies. Currently, methods for controlling VOCs include adsorption, condensation, biodegradation, and catalytic oxidation. Among these, catalytic oxidation is considered one of the mainstream methods for VOCs treatment, and its core lies in the development and selection of catalysts, as catalyst performance directly determines VOCs degradation efficiency. Various synthetic catalysts have been developed, such as precious metal catalysts, transition metal catalysts, and supported catalysts, and these catalysts have achieved high performance. Given the current resource shortage, research on catalysts prepared through resource utilization has become a new path to alleviate resource problems. With the electric vehicle industry and the future demand for energy storage batteries, the market output of lithium-ion batteries has experienced extremely high growth in recent years. However, retired and used lithium-ion batteries will become new solid waste pollutants, placing a serious burden on environmental governance. Lithium-ion batteries contain important recyclable transition metal components such as manganese, cobalt, lithium, and nickel, which are considered a kind of "man-made mineral" and a resource that can alleviate the rapid depletion of strategic metals and the potential risks of environmental pollution.

[0004] The recycling of spent lithium-ion batteries to prepare catalysts for the oxidation and degradation of pollutants is of great practical significance for improving VOCs air pollution and synergistically reducing waste pollution to the atmosphere, providing a new approach to resource recycling. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a nitrogen-doped NiCoMnO4 based on waste lithium-ion battery cathode material. x Catalysts and their application in the catalytic oxidation of volatile organic compounds (VOCs). This invention uses spent lithium-ion battery cathode materials as the metal source, and constructs a multi-metal synergistic NiCoMnO4 catalyst rich in active oxygen species through a combination of lithium removal by ammonium sulfate roasting and controlled nitrogen introduction. x The catalytic system is suitable for low-temperature VOCs catalytic oxidation reactions and features economic efficiency, resource utilization, and environmental friendliness.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing nitrogen-doped NiCoMnO based on waste lithium-ion battery cathode materials. x The catalyst method includes the following steps: S1. Disassemble the fully discharged waste nickel-cobalt-manganese ternary lithium battery, separate the positive electrode sheet, cut it and calcine it in air atmosphere to remove organic binder and carbon material, and obtain positive electrode active metal powder rich in Ni, Co and Mn oxides. S2. The positive electrode active metal powder obtained in S1 is mixed and ground with a separating agent, and then subjected to two-stage heating and calcination in air atmosphere to enrich Ni, Co, and Mn in the form of composite precursors and achieve selective separation from Li. The calcined sample is washed with water, stirred, subjected to solid-liquid separation, and dried to obtain insoluble NiCoMnO. x Precursor; S3, the NiCoMnO obtained in S2 x The precursor was mixed and ground with urea, and then calcined under a nitrogen atmosphere to dope nitrogen into NiCoMnO. x Nitrogen-doped NiCoMnO is formed in the crystal lattice or surface structure. x catalyst.

[0007] Preferably, the waste nickel-cobalt-manganese ternary lithium battery mentioned in S1 includes commonly available nickel-cobalt-manganese ternary lithium-ion batteries such as NCM333, NCM523, NCM532, NCM622, and NCM811, with NCM523 being particularly suitable; the final positive electrode active metal powder has a Li content of 6.4±1.4wt%, a Ni content of 26.09±14wt%, a Co content of 10.29±10wt%, and a Mn content of 13.90±11wt%.

[0008] Preferably, the calcination temperature in S1 is 350~450℃ and the calcination time is 1~1.5h.

[0009] Preferably, the separating agent in S2 is ammonium sulfate or ammonium carbonate, and the mass ratio of the separating agent to the positive electrode active metal powder is (0.8~1.8):1; the grinding time is 30~60 min.

[0010] Preferably, the two-stage heating and calcination in S2 is as follows: the first stage is 350~450℃, held for 30~40min; the second stage is 550~650℃, held for 40~60min.

[0011] Preferably, the temperature for washing and stirring the calcined sample in step S2 is 50~65℃, and the time is 1h.

[0012] Preferably, the drying temperature in S2 is 50~70℃ and the drying time is 8~12h.

[0013] Preferably, S3 contains NiCoMnO x The mass ratio of precursor to urea is 1:(1~3); the grinding time is 30~60 min.

[0014] Preferably, the flow rate of nitrogen in S3 is 20 mL / min; the calcination temperature is 400~450℃, and the time is 60~90 min.

[0015] The present invention also provides a nitrogen-doped NiCoMnO prepared by the above method. x catalyst.

[0016] The present invention also provides a nitrogen-doped NiCoMnO as described above. x Application of catalysts in the catalytic oxidation of VOCs.

[0017] This invention has significant technical advantages compared to existing technologies: 1. This invention relates to the recovery of NiCoMnO from spent lithium-ion batteries. x Catalysts enable the resource utilization of waste materials, recovering valuable components through pyrometallurgical technology, avoiding the chemical consumption and environmental impact of hydrometallurgy. Simultaneously, a one-step pyrometallurgical process is used to remove lithium and directly obtain the target NiCoMnO. x The oxide polymerization process reduces the steps required for further extraction of valuable components Ni, Co, and Mn. The resulting NiCoMnO xThe catalyst, with Ni, Co, and Mn as its main active components, accelerates the transfer of reactive oxygen species during the catalytic reaction, thereby enhancing its reactivity. Nitrogen incorporation optimizes the catalyst's pore structure, increases its specific surface area, and improves electron transfer, increasing the proportion of low-valent Mn and Co, as well as trivalent Ni, which is beneficial for catalytic oxidation. Furthermore, nitrogen incorporation promotes stronger interactions between Mn and N, lowering the reaction temperature and facilitating the reaction process.

[0018] 2. This invention is based on nitrogen-doped NiCoMnO4 from spent lithium-ion battery cathode materials. x The catalyst preparation method is simple, easy to operate and implement, and compared with chemically synthesized catalysts, it has the characteristics of being environmentally friendly and economical, and has broad application prospects.

[0019] 3. The nitrogen-doped NiCoMnO of the present invention x The catalyst can be used for the catalytic oxidation of VOCs. During the catalytic oxidation process, nitrogen-doped NiCoMnO... x The catalyst can participate in the reaction through surface-active oxygen species, reducing the apparent activation energy of the reaction, thereby achieving efficient oxidation and conversion of VOCs at lower temperatures. The resource-recovery catalyst prepared in this invention for treating VOCs in waste gas or tail gas can effectively overcome the shortcomings of traditional VOCs oxidation catalysts, such as narrow reaction temperature window, susceptibility to poisoning, and harm to the environment and human health. It has the advantages of high efficiency, economy, environmental friendliness, and high resource utilization.

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 It is the positive electrode active metal powder (BK) and NiCoMnO of Example 1 of this invention. x Precursor (NCM) and nitrogen-doped NiCoMnO x XRD pattern of the catalyst (NCM-N); Figure 2 It is the positive electrode active metal powder (BK) and nitrogen-doped NiCoMnO of Example 1 of this invention. x TEM images of the catalyst (NCM-N), (a) BK, (b) NCM-N; Figure 3 This is a performance diagram of the catalytic oxidation of toluene by the positive electrode active metal powder (BK) in Example 4 of the present invention; Figure 4 It is NiCoMnO in Embodiment 4 of the present invention x Performance graph of precursor (NCM) catalytic oxidation of toluene; Figure 5 It is the nitrogen-doped NiCoMnO in Example 4 of this invention. x Performance diagram of the catalyst (NCM-N) for the catalytic oxidation of toluene. Detailed Implementation

[0022] Example 1 This embodiment describes a method for preparing nitrogen-doped NiCoMnO based on cathode materials from spent lithium-ion batteries. x The catalyst method includes the following steps: S1. Disassemble the fully discharged waste NCM523 lithium-ion battery to obtain the positive electrode sheet. Cut the positive electrode sheet into 2×2cm pieces and arrange them neatly in a crucible, ensuring the stacking height does not exceed the edge of the crucible. Place the crucible in a muffle furnace and heat it to 350℃ at a heating rate of 5℃ / min, holding it for 1 hour to remove organic binders and carbon materials. After cooling to room temperature, remove the battery and scrape off the black powder adhering to the positive electrode copper foil with a scraper to obtain a positive electrode active metal powder rich in Ni, Co, and Mn oxides, denoted as BK.

[0023] S2. Take 3g of the positive electrode active metal powder obtained in S1 and mix it with 3g of ammonium sulfate. Grind the mixture in an agate mortar for 50min. Then, place the ground mixture in a tube furnace connected to air. First, heat the mixture to 350℃ at a heating rate of 5℃ / min and hold for 30min. Then, heat the mixture to 600℃ at a heating rate of 5℃ / min and hold for 60min. This allows Ni, Co, and Mn to be enriched in the form of composite precursors and selectively separated from Li. After cooling to room temperature, remove the sample and add it to a beaker containing 200mL of ultrapure water. Stir at 60℃ for 1h to obtain lithium sulfate and insoluble NiCoMnO. x The suspension of the precursor was filtered while hot to obtain insoluble NiCoMnO. x The precursor was dried in a forced-air drying oven at 60°C for 10 hours to obtain NiCoMnO. x The precursor is denoted as NCM.

[0024] S3, the NiCoMnO obtained in S2 x The precursor and urea were mixed at a mass ratio of 1:1 and ground in an agate mortar for 60 min. The resulting mixture was placed in a tube furnace, and nitrogen gas was introduced at a flow rate of 20 mL / min. The temperature was increased to 400 °C at a heating rate of 5 °C / min and held for 90 min to allow nitrogen to be doped into NiCoMnO. x After cooling and removal from the lattice or surface structure, nitrogen-doped NiCoMnO with oxygen-rich vacancies and enhanced oxygen migration ability is obtained. x Catalyst, denoted as NCM-N.

[0025] Figure 1Positive electrode active metal powder (BK), NiCoMnO x Precursor (NCM) and nitrogen-doped NiCoMnO x XRD pattern of catalyst (NCM-N). The figure shows that the original battery black powder BK exhibits characteristic peaks consistent with NCM523; after lithium removal, the NCM precursor regenerates a crystal structure with a special morphology, forming a mixed spinel product mainly composed of spinel-type transition metal oxides (Mn2CoO4 and MnCo2O4) and defective spinel oxides (Ni6MnO8); nitrogen-doped NiCoMnO... x The catalyst exhibits multiphase composite characteristics of NiO and CoO. This indicates that the nitrogen-doped NiCoMnO of the present invention... x In the catalyst preparation process, calcination with a separating agent converts lithium elements, which contribute little to catalytic performance, into soluble lithium salts, which are then removed, yielding a composite precursor rich in Ni, Co, and Mn. Subsequently, nitrogen doping is achieved through urea-assisted calcination, resulting in nitrogen-doped NiCoMnO. x The catalyst contains multi-metal oxide phases such as NiO and MnCo2O4. Nitrogen exists in the form of metal-nitrogen-oxygen bonding or surface coordination. The introduction of nitrogen modulates the electronic structure of transition metals, increasing the proportion of high-activity valence states in Ni, Co, and Mn. At the same time, it induces the formation of more oxygen vacancies on the catalyst surface and near-surface region, which is conducive to the generation and migration of active oxygen species and enhances the reversible adsorption and desorption capacity of oxygen.

[0026] Figure 2 It is positive electrode active metal powder (BK) and nitrogen-doped NiCoMnO x TEM image of the catalyst (NCM-N). (By...) Figure 2 (a) It can be seen that the original waste battery cathode powder (BK) exhibits a layered structure, with lattice fringes of 0.528 nm width, typical of α-NaFeO2 layered oxides. (From...) Figure 2 (b) It can be seen that NiCoMnO after lithium removal and nitrogen doping x TEM images of the catalyst (NCM-N) show distinct partitioning within the region, which can be observed through analysis of... Figure 2In (b), the orange, purple, green, blue, and gray regions yielded five different lattice fringe widths, corresponding to Mn2CoO4, Ni6MnO8, MnCo2O4, NiO, and CoO, respectively. The lattice fringe data showed that the (400) plane of Mn2CoO4 increased from 0.207 nm to 0.219 nm (b-1), and the (311) plane of Ni6MnO8 increased from 0.250 nm to 0.278 nm (b-2). The (222) plane of MnCo2O4 increased slightly from 0.239 nm to 0.240 nm (b-3), the (012) plane of NiO increased from 0.209 nm to 0.225 nm (b-4), and the (200) plane of CoO increased from 0.210 nm to 0.231 nm (b-5). These changes in lattice fringes show that significant lattice expansion occurred after nitrogen doping, proving that nitrogen doping and delithiation performed defect reconstruction on the original battery structure.

[0027] Example 2 This embodiment describes a method for preparing nitrogen-doped NiCoMnO based on cathode materials from spent lithium-ion batteries. x The catalyst method includes the following steps: S1. Disassemble the fully discharged waste NCM532 lithium-ion battery, separate the positive electrode sheet, cut the positive electrode sheet into 2×2cm pieces and arrange them neatly in a crucible, place it in a muffle furnace, heat it to 400℃ at a heating rate of 5℃ / min and hold it for 1.5h. After cooling to room temperature, take it out, scrape off the black powder adhering to the positive electrode copper foil with a scraper and collect it to obtain positive electrode active metal powder.

[0028] S2. Take 3g of the positive electrode active metal powder obtained in S1 and mix it with 2.4g of ammonium sulfate. Grind the mixture in an agate mortar for 30min. Then, place the ground mixture in a tube furnace connected to air. First, heat the mixture to 400℃ at a heating rate of 5℃ / min and hold for 40min. Then, heat the mixture to 550℃ at a heating rate of 5℃ / min and hold for 40min. After cooling to room temperature, remove the sample and add it to a beaker containing 200mL of ultrapure water. Stir the mixture at 50℃ for 1h to obtain lithium sulfate and insoluble NiCoMnO. x The suspension of the precursor was filtered while hot to obtain insoluble NiCoMnO. x The precursor was dried in a 50°C forced-air drying oven for 12 hours to obtain NiCoMnO. x Precursor.

[0029] S3, the NiCoMnO obtained in S2 xThe precursor and urea were mixed at a mass ratio of 1:2 and ground in an agate mortar for 30 min. The resulting mixture was placed in a tube furnace, and nitrogen gas was introduced at a flow rate of 20 mL / min. The temperature was increased to 450 °C at a heating rate of 5 °C / min and held for 60 min. After cooling, the mixture was removed to obtain nitrogen-doped NiCoMnO. x catalyst.

[0030] Example 3 This embodiment describes a method for preparing nitrogen-doped NiCoMnO based on cathode materials from spent lithium-ion batteries. x The catalyst method includes the following steps: S1. Disassemble the fully discharged waste NCM622 lithium-ion battery, separate the positive electrode sheet, cut the positive electrode sheet into 2×2cm pieces and arrange them neatly in a crucible, place it in a muffle furnace, heat it to 450℃ at a heating rate of 5℃ / min and hold it for 1 hour. After cooling to room temperature, take it out, scrape off the black powder adhering to the positive electrode copper foil with a scraper and collect it to obtain positive electrode active metal powder.

[0031] S2. Take 3g of the positive electrode active metal powder obtained in S1 and mix it with 5.4g of ammonium carbonate. Grind the mixture in an agate mortar for 60min. Then, place the ground mixture in a tube furnace connected to air. First, heat the mixture to 450℃ at a heating rate of 5℃ / min and hold for 30min. Then, heat the mixture to 650℃ at a heating rate of 5℃ / min and hold for 50min. After cooling to room temperature, remove the sample and add it to a beaker containing 200mL of ultrapure water. Stir the mixture at 65℃ for 1h to obtain lithium sulfate and insoluble NiCoMnO. x The suspension of the precursor was filtered while hot to obtain insoluble NiCoMnO. x The precursor was dried in a forced-air drying oven at 70°C for 8 hours to obtain NiCoMnO. x Precursor.

[0032] S3, the NiCoMnO obtained in S2 x The precursor and urea were mixed at a mass ratio of 1:3 and ground in an agate mortar for 50 min. The resulting mixture was placed in a tube furnace, and nitrogen gas was introduced at a flow rate of 20 mL / min. The temperature was increased to 420 °C at a heating rate of 5 °C / min and held for 75 min. After cooling, the mixture was removed to obtain nitrogen-doped NiCoMnO. x catalyst.

[0033] Example 4 This embodiment uses nitrogen-doped NiCoMnO. x Application of catalysts in the catalytic oxidation of VOCs.

[0034] The positive electrode active metal powder (BK) and NiCoMnO prepared in Example 1 were used.x Precursor (NCM) and nitrogen-doped NiCoMnO x The catalysts (NCM-N) were used for the catalytic oxidation of toluene, as follows: The catalyst was sieved into 40-60 mesh particles. Approximately 0.2 g of the sieved catalyst was placed in a quartz reaction tube, and the tube was kept at atmospheric pressure (101 kPa). The catalyst bed was maintained at a height of 0.6 cm, and the space velocity was measured at 30,000 h⁻¹. -1 The simulated gas mixture used in the test consisted of 400 ppm C7H8 and 20% O2 / N2 (v / v) as the carrier gas, with a total gas flow rate of 100 mL / min. The reaction temperature ranged from 150 to 350 °C, with a heating interval of 25 °C. Samples were taken after stabilizing at each temperature for 30 min to ensure the catalytic reaction reached equilibrium. Before testing each sample, 200 mL / min of 20% O2 / N2 was introduced and maintained at 350 °C for 30 min to activate the catalyst. After activation, the catalyst was cooled to 150 °C, and then the simulated gas mixture was introduced. After stabilization, the toluene oxidation reaction began. The concentrations of various gas components in the inlet and outlet simulated gas mixtures were qualitatively and quantitatively analyzed by gas chromatography.

[0035] Figure 3 This is a graph showing the catalytic oxidation performance of BK. Figure 4 This is a diagram showing the catalytic oxidation performance of the NCM precursor; Figure 5 It is nitrogen-doped NiCoMnO x Catalytic oxidation performance diagram of the catalyst. From Figure 3 It can be seen that the active components in the original battery powder have certain advantages in the catalytic oxidation of toluene; Figure 4 It can be observed that removing lithium leads to a stronger improvement in catalytic performance, with a significant enhancement in catalytic performance at high temperatures; compared to... Figure 5 It can be observed that nitrogen doping effectively enhances the catalyst activity, achieving 100% conversion at 250℃ and effectively reducing the reaction temperature; this indicates that nitrogen doping can effectively activate the active components in spent lithium-ion batteries to exert their catalytic effect. Compared with the undoped NCM precursor, the nitrogen-doped NiCoMnO obtained in this invention... x The catalyst exhibits a lower complete conversion temperature and better reaction stability in the catalytic oxidation of VOCs, and is particularly suitable for the oxidation of aromatic hydrocarbon VOCs under oxygen-containing conditions.

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing nitrogen-doped NiCoMnO based on spent lithium-ion battery cathode materials x The catalyst method is characterized by, Includes the following steps: S1. Disassemble the fully discharged waste nickel-cobalt-manganese ternary lithium battery, separate the positive electrode sheet, cut it and calcine it in air atmosphere to remove organic binder and carbon material, and obtain positive electrode active metal powder rich in Ni, Co and Mn oxides. S2. The positive electrode active metal powder obtained in S1 is mixed and ground with a separating agent, and then subjected to two-stage heating and calcination in air atmosphere to enrich Ni, Co, and Mn in the form of composite precursors and achieve selective separation from Li. The calcined sample is washed with water, stirred, subjected to solid-liquid separation, and dried to obtain insoluble NiCoMnO. x Precursor; S3, the NiCoMnO obtained in S2 x The precursor was mixed and ground with urea, and then calcined under a nitrogen atmosphere to dope nitrogen into NiCoMnO. x Nitrogen-doped NiCoMnO is formed in the crystal lattice or surface structure. x catalyst.

2. The method according to claim 1, characterized in that, The calcination temperature described in S1 is 350~450℃, and the calcination time is 1~1.5h.

3. The method according to claim 1, characterized in that, The separating agent in S2 is ammonium sulfate or ammonium carbonate, and the mass ratio of the separating agent to the positive electrode active metal powder is (0.8~1.8):1; the grinding time is 30~60 min.

4. The method according to claim 1, characterized in that, The two-stage heating and calcination described in S2 are as follows: the first stage is 350~450℃, held for 30~40min; the second stage is 550~650℃, held for 40~60min.

5. The method according to claim 1, characterized in that, The temperature for washing and stirring the calcined sample described in S2 is 50~65℃, and the time is 1h.

6. The method according to claim 1, characterized in that, The drying temperature described in S2 is 50~70℃, and the time is 8~12h.

7. The method according to claim 1, characterized in that, S3 NiCoMnO x The mass ratio of precursor to urea is 1:(1~3), and the grinding time is 30~60 min.

8. The method according to claim 1, characterized in that, The nitrogen flow rate in S3 is 20 mL / min; the calcination temperature is 400~450℃, and the time is 60~90 min.

9. A nitrogen-doped NiCoMnO prepared by the method according to any one of claims 1 to 8 x catalyst.

10. A nitrogen-doped NiCoMnO according to claim 9 x Application of catalysts in the catalytic oxidation of VOCs.

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