Method for recovering nmp cleaning agent
By reacting a complexing agent with NMP to generate complex clusters, and combining this with membrane filtration and vacuum distillation, the problems of high difficulty and high energy consumption in NMP cleaning agent recovery are solved. This achieves efficient, low-consumption, and environmentally friendly NMP recovery, improving the solubility rate and reducing waste gas emissions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUJIAN XFH NEW ENERGY MATERIALS CO LTD
- Filing Date
- 2026-03-09
- Publication Date
- 2026-07-07
AI Technical Summary
In existing wet cleaning processes, NMP cleaning agent recovery is difficult, energy-intensive, and costly, and it is prone to generating toxic waste gas. Existing recovery technologies have failed to effectively address the unique characteristics of the PVDF dissolution system, resulting in insufficient solvent purity and affecting the secondary cleaning effect.
A complexing agent is used to react with NMP to generate complex clusters. After separating PVDF through a filter membrane, the complexes are decomplexed, and NMP is purified by vacuum distillation. This is simplified into a five-step recovery method, including dissolving PVDF, precipitating PVDF, solid-liquid separation, releasing organic solvents, and purifying NMP.
It significantly reduces energy consumption and exhaust emissions, improves NMP recovery efficiency, achieves a dissolution rate of up to 91%, reduces cleaning costs, and minimizes environmental pollution.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of recycling technology, and in particular to a method for recycling NMP cleaning agents. Background Technology
[0002] In the production and recycling of new energy devices such as lithium-ion batteries and sodium-ion batteries, PVDF is a commonly used binder and needs to be removed by cleaning with organic solvents. Currently, the mainstream cleaning solvents include DMC and NMP, which have excellent dissolving properties for PVDF and can achieve efficient cleaning.
[0003] However, existing wet cleaning processes have significant technical drawbacks: First, organic solvent recovery is difficult, and traditional distillation recovery methods are energy-intensive and costly, resulting in low solvent reuse rates and significant solvent waste. Second, organic solvents such as DMC and NMP are highly volatile, easily generating toxic waste gases during the cleaning process, requiring expensive tail gas treatment systems, increasing equipment investment and operating costs, and posing environmental risks. Third, existing recovery technologies mostly focus on solvent purification, without designing specific recovery schemes for the unique characteristics of the PVDF dissolution system, easily leading to insufficient purity of the recovered solvent and affecting the secondary cleaning effect. While there have been attempts to recover organic solvents using chelating resins and extractants, chelating resins have poor adsorption specificity for DMC and NMP, are easily affected by impurities, and the desorption process is complex; extraction methods require the introduction of additional extraction solvents, easily causing secondary pollution, and are difficult to adapt to the process requirements of PVDF cleaning. Therefore, there is an urgent need for an efficient, low-consumption, and environmentally friendly organic solvent recovery and reuse scheme to address the pain points of existing wet cleaning processes. Summary of the Invention
[0004] In view of this, the present invention addresses the deficiencies of the existing technology, and its main objective is to provide a method for recovering NMP cleaning agent, which can effectively recover and recycle NMP cleaning agent, reduce cleaning costs, and significantly reduce exhaust emissions.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for recovering NMP cleaning agent, comprising the following steps: (1) Dissolving PVDF: Place the PVDF-containing battery electrode in a cleaning device, add NMP cleaning agent, stir and clean, the cleaning temperature is 60℃, the solid-liquid ratio is 1:10 (g / mL), and the cleaning time is 60min to obtain PVDF-NMP mixture; (2) Precipitation of PVDF: Add a complexing agent to the PVDF-NMP mixture obtained in step (1), the mass ratio of the complexing agent to NMP is 1:(8-25), the reaction temperature is 45-70℃, the stirring rate is 250r / min, the reaction time is 60min, and PVDF is precipitated to obtain a mixture; (3) Solid-liquid separation: The mixture obtained in step (2) is filtered by a filter membrane to remove the precipitated PVDF and collect the NMP complex cluster solution; (4) Release organic solvent: The NMP complex cluster solution collected in step (3) is introduced into the decomplexing device, heated to 90°C, and kept at the temperature for 80 min to achieve decomplexing and release NMP; (5) Purification of NMP: The NMP released in step (4) is subjected to vacuum distillation at a pressure of 0.05 MPa and a temperature of 120 °C to obtain reusable NMP.
[0006] As a preferred embodiment, in step (2), the complexing agent is a polyethylene glycol derivative.
[0007] As a preferred embodiment, in step (2), the molecular weight of the complexing agent is 4000.
[0008] As a preferred embodiment, in step (3), the pore size of the filter membrane is 0.5 μm.
[0009] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution: After PVDF is dissolved, a complexing agent is added. NMP reacts with the complexing agent to form complex clusters. After filtration, the complexes are decomposed to obtain NMP with high purity. Compared with the traditional process that requires two vacuum distillations, the method of this invention only requires one vacuum distillation, which is faster, more efficient, and significantly reduces energy consumption and waste gas emissions.
[0010] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to several specific embodiments. Detailed Implementation
[0011] This invention discloses a method for recovering NMP cleaning agent, which includes the following steps: (1) Dissolving PVDF: Place the battery electrode containing PVDF in a cleaning device, add NMP cleaning agent, stir and clean, the cleaning temperature is 60℃, the solid-liquid ratio is 1:10 (g / mL), and the cleaning time is 60min to obtain PVDF-NMP mixture.
[0012] (2) Precipitation of PVDF: Add a complexing agent to the PVDF-NMP mixture obtained in step (1), the mass ratio of the complexing agent to NMP is 1:(8-25), the reaction temperature is 45-70℃, the stirring rate is 250r / min, the reaction time is 60min, and PVDF is precipitated to obtain a mixture; the complexing agent is a polyethylene glycol derivative and the molecular weight of the complexing agent is 4000.
[0013] (3) Solid-liquid separation: The mixture obtained in step (2) is filtered by a filter membrane to remove the precipitated PVDF and collect the NMP complex cluster solution; the pore size of the filter membrane is 0.5 μm.
[0014] (4) Release organic solvent: Introduce the NMP complex cluster solution collected in step (3) into the decomplexing device, heat it to 90°C, and keep it at that temperature for 80 min to achieve decomplexing and release NMP.
[0015] (5) Purification of NMP: The NMP released in step (4) is subjected to vacuum distillation at a pressure of 0.05 MPa and a temperature of 120 °C to obtain reusable NMP.
[0016] The following detailed description is provided in conjunction with several embodiments and comparative examples.
[0017] Example 1 (1) Dissolving PVDF: Place the battery electrode containing PVDF in a cleaning device, add NMP cleaning agent, stir and clean, the cleaning temperature is 60℃, the solid-liquid ratio is 1:10 (g / mL), and the cleaning time is 60min to obtain PVDF-NMP mixture.
[0018] (2) Precipitation of PVDF: Add a complexing agent to the PVDF-NMP mixture obtained in step (1), the mass ratio of the complexing agent to NMP is 1:25, the reaction temperature is 45℃, the stirring rate is 250r / min, the reaction time is 60min, and PVDF is precipitated to obtain a mixture; the complexing agent is a polyethylene glycol derivative and the molecular weight of the complexing agent is 4000.
[0019] (3) Solid-liquid separation: The mixture obtained in step (2) is filtered by a filter membrane to remove the precipitated PVDF and collect the NMP complex cluster solution; the pore size of the filter membrane is 0.5 μm.
[0020] (4) Release organic solvent: Introduce the NMP complex cluster solution collected in step (3) into the decomplexing device, heat it to 90°C, and keep it at that temperature for 80 min to achieve decomplexing and release NMP.
[0021] (5) Purification of NMP: The NMP released in step (4) is subjected to vacuum distillation at a pressure of 0.05 MPa and a temperature of 120 °C to obtain reusable NMP.
[0022] Example 2 (1) Dissolving PVDF: Place the battery electrode containing PVDF in a cleaning device, add NMP cleaning agent, stir and clean, the cleaning temperature is 60℃, the solid-liquid ratio is 1:10 (g / mL), and the cleaning time is 60min to obtain PVDF-NMP mixture.
[0023] (2) Precipitation of PVDF: Add a complexing agent to the PVDF-NMP mixture obtained in step (1), the mass ratio of the complexing agent to NMP is 1:8, the reaction temperature is 45℃, the stirring rate is 250r / min, the reaction time is 60min, and PVDF is precipitated to obtain a mixture; the complexing agent is a polyethylene glycol derivative and the molecular weight of the complexing agent is 4000.
[0024] (3) Solid-liquid separation: The mixture obtained in step (2) is filtered by a filter membrane to remove the precipitated PVDF and collect the NMP complex cluster solution; the pore size of the filter membrane is 0.5 μm.
[0025] (4) Release organic solvent: Introduce the NMP complex cluster solution collected in step (3) into the decomplexing device, heat it to 90°C, and keep it at that temperature for 80 min to achieve decomplexing and release NMP.
[0026] (5) Purification of NMP: The NMP released in step (4) is subjected to vacuum distillation at a pressure of 0.05 MPa and a temperature of 120 °C to obtain reusable NMP.
[0027] Example 3 (1) Dissolving PVDF: Place the battery electrode containing PVDF in a cleaning device, add NMP cleaning agent, stir and clean, the cleaning temperature is 60℃, the solid-liquid ratio is 1:10 (g / mL), and the cleaning time is 60min to obtain PVDF-NMP mixture.
[0028] (2) Precipitation of PVDF: Add a complexing agent to the PVDF-NMP mixture obtained in step (1), the mass ratio of the complexing agent to NMP is 1:25, the reaction temperature is 70℃, the stirring rate is 250r / min, the reaction time is 60min, and PVDF is precipitated to obtain a mixture; the complexing agent is a polyethylene glycol derivative and the molecular weight of the complexing agent is 4000.
[0029] (3) Solid-liquid separation: The mixture obtained in step (2) is filtered by a filter membrane to remove the precipitated PVDF and collect the NMP complex cluster solution; the pore size of the filter membrane is 0.5 μm.
[0030] (4) Release organic solvent: Introduce the NMP complex cluster solution collected in step (3) into the decomplexing device, heat it to 90°C, and keep it at that temperature for 80 min to achieve decomplexing and release NMP.
[0031] (5) Purification of NMP: The NMP released in step (4) is subjected to vacuum distillation at a pressure of 0.05 MPa and a temperature of 120 °C to obtain reusable NMP.
[0032] Example 4 (1) Dissolving PVDF: Place the battery electrode containing PVDF in a cleaning device, add NMP cleaning agent, stir and clean, the cleaning temperature is 60℃, the solid-liquid ratio is 1:10 (g / mL), and the cleaning time is 60min to obtain PVDF-NMP mixture.
[0033] (2) Precipitation of PVDF: Add a complexing agent to the PVDF-NMP mixture obtained in step (1), the mass ratio of the complexing agent to NMP is 1:16, the reaction temperature is 60℃, the stirring rate is 250r / min, the reaction time is 60min, and PVDF is precipitated to obtain a mixture; the complexing agent is a polyethylene glycol derivative and the molecular weight of the complexing agent is 4000.
[0034] (3) Solid-liquid separation: The mixture obtained in step (2) is filtered by a filter membrane to remove the precipitated PVDF and collect the NMP complex cluster solution; the pore size of the filter membrane is 0.5 μm.
[0035] (4) Release organic solvent: Introduce the NMP complex cluster solution collected in step (3) into the decomplexing device, heat it to 90°C, and keep it at that temperature for 80 min to achieve decomplexing and release NMP.
[0036] (5) Purification of NMP: The NMP released in step (4) is subjected to vacuum distillation at a pressure of 0.05 MPa and a temperature of 120 °C to obtain reusable NMP.
[0037] Example 5 (1) Dissolving PVDF: Place the battery electrode containing PVDF in a cleaning device, add NMP cleaning agent, stir and clean, the cleaning temperature is 60℃, the solid-liquid ratio is 1:10 (g / mL), and the cleaning time is 60min to obtain PVDF-NMP mixture.
[0038] (2) Precipitation of PVDF: Add a complexing agent to the PVDF-NMP mixture obtained in step (1), the mass ratio of the complexing agent to NMP is 1:12, the reaction temperature is 50℃, the stirring rate is 250r / min, the reaction time is 60min, and PVDF is precipitated to obtain a mixture; the complexing agent is a polyethylene glycol derivative and the molecular weight of the complexing agent is 4000.
[0039] (3) Solid-liquid separation: The mixture obtained in step (2) is filtered by a filter membrane to remove the precipitated PVDF and collect the NMP complex cluster solution; the pore size of the filter membrane is 0.5 μm.
[0040] (4) Release organic solvent: Introduce the NMP complex cluster solution collected in step (3) into the decomplexing device, heat it to 90°C, and keep it at that temperature for 80 min to achieve decomplexing and release NMP.
[0041] (5) Purification of NMP: The NMP released in step (4) is subjected to vacuum distillation at a pressure of 0.05 MPa and a temperature of 120 °C to obtain reusable NMP.
[0042] Example 6 (1) Dissolving PVDF: Place the battery electrode containing PVDF in a cleaning device, add NMP cleaning agent, stir and clean, the cleaning temperature is 60℃, the solid-liquid ratio is 1:10 (g / mL), and the cleaning time is 60min to obtain PVDF-NMP mixture.
[0043] (2) Precipitation of PVDF: Add a complexing agent to the PVDF-NMP mixture obtained in step (1), the mass ratio of the complexing agent to NMP is 1:20, the reaction temperature is 55℃, the stirring rate is 250r / min, the reaction time is 60min, and PVDF is precipitated to obtain a mixture; the complexing agent is a polyethylene glycol derivative and the molecular weight of the complexing agent is 4000.
[0044] (3) Solid-liquid separation: The mixture obtained in step (2) is filtered by a filter membrane to remove the precipitated PVDF and collect the NMP complex cluster solution; the pore size of the filter membrane is 0.5 μm.
[0045] (4) Release organic solvent: Introduce the NMP complex cluster solution collected in step (3) into the decomplexing device, heat it to 90°C, and keep it at that temperature for 80 min to achieve decomplexing and release NMP.
[0046] (5) Purification of NMP: The NMP released in step (4) is subjected to vacuum distillation at a pressure of 0.05 MPa and a temperature of 120 °C to obtain reusable NMP.
[0047] Comparative Example 1 (1) Dissolving PVDF: Place the battery electrode containing PVDF in a cleaning device, add NMP cleaning agent, stir and clean, the cleaning temperature is 60℃, the solid-liquid ratio is 1:10 (g / mL), and the cleaning time is 60min to obtain PVDF-NMP mixture.
[0048] (2) Separation of PVDF: The PVDF-NMP mixture obtained in step (1) is subjected to vacuum distillation to initially separate PVDF. The distillation pressure is 0.05 MPa, the distillation temperature is 120℃, and the distillation time is 90 min. The PVDF precipitate is removed to obtain crude NMP solution.
[0049] (3) Purification of NMP: The crude NMP solution obtained in step (2) is subjected to secondary vacuum distillation at a pressure of 0.05 MPa and a temperature of 120 °C to obtain reusable NMP.
[0050] The various embodiments and comparative examples were tested, and the test results are shown in Table 1.
[0051]
[0052] Table 1 Analysis of the above data shows that the recycling method of the present invention can improve the recycling efficiency of NMP, reduce the amount of waste gas emissions and energy consumption. After being reused 5 times, the dissolution rate of PVDF is still as high as 91% or more. The process parameters of Example 1 can better recover NMP. Compared with Comparative Example 1, the recycling efficiency of Example 1 is higher, 17% higher than that of Comparative Example 1. After being reused 5 times, the dissolution rate of PVDF is 5% higher than that of Comparative Example 1, and the amount of waste gas emissions is only 15% of that of Comparative Example 1, which is more environmentally friendly and has achieved significant progress.
[0053] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.
Claims
1. A method for recovering NMP cleaning agent, characterized in that: It includes the following steps: (1) Dissolving PVDF: Place the PVDF-containing battery electrode in a cleaning device, add NMP cleaning agent, stir and clean, the cleaning temperature is 60℃, the solid-liquid ratio is 1:10 (g / mL), and the cleaning time is 60min to obtain PVDF-NMP mixture; (2) Precipitation of PVDF: Add a complexing agent to the PVDF-NMP mixture obtained in step (1), the mass ratio of the complexing agent to NMP is 1:(8-25), the reaction temperature is 45-70℃, the stirring rate is 250r / min, the reaction time is 60min, and PVDF is precipitated to obtain a mixture; (3) Solid-liquid separation: The mixture obtained in step (2) is filtered by a filter membrane to remove the precipitated PVDF and collect the NMP complex cluster solution; (4) Release organic solvent: The NMP complex cluster solution collected in step (3) is introduced into the decomplexing device, heated to 90°C, and kept at the temperature for 80 min to achieve decomplexing and release NMP; (5) Purification of NMP: The NMP released in step (4) is subjected to vacuum distillation at a pressure of 0.05 MPa and a temperature of 120 °C to obtain reusable NMP.
2. The method for recovering NMP cleaning agent according to claim 1, characterized in that: In step (2), the complexing agent is a polyethylene glycol derivative.
3. The method for recovering NMP cleaning agent according to claim 2, characterized in that: In step (2), the molecular weight of the complexing agent is 4000.
4. The method for recovering NMP cleaning agent according to claim 1, characterized in that: In step (3), the pore size of the filter membrane is 0.5 μm.