High-efficiency depolymerization method for photovoltaic module EVA (Ethylene Vinyl Acetate) adhesive film based on functionalized ionic liquid

Abstract

The invention discloses an efficient depolymerization method for a photovoltaic module EVA (Ethylene Vinyl Acetate) adhesive film based on a functionalized ionic liquid, which is characterized in that depolymerization under neutral / mild conditions is realized through directional catalysis of metal halide anions in choline chloride-metal chloride ionic liquid and an ultrasonic-thermal synergistic effect, and the depolymerization time is shortened to be within 3 hours; according to the method, the photovoltaic glass substrate is completely reserved, so that the photovoltaic glass and the EVA adhesive film are efficiently separated in an environment-friendly manner, no VOCs are discharged, and the choline chloride-metal chloride ionic liquid catalyst can be recycled and regenerated and is low in cost.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic module recycling, and in particular to a method for efficiently depolymerizing an EVA film of a photovoltaic module based on functionalized ionic liquid. Background Art

[0002] The ethylene-vinyl acetate (EVA) film used as the encapsulation material in photovoltaic modules is difficult to efficiently remove after the modules have reached the end of their service life. Its chemical stability leads to high glass breakage rates and incomplete material separation in traditional physical recycling methods. Current depolymerization technologies for EVA film mainly include thermal decomposition and solvent methods. The thermal decomposition method involves thermal cracking EVA at 400-600°C in an oxygen-free environment, producing low-molecular-weight hydrocarbon products. The thermal decomposition method consumes >800 kWh of energy per ton of photovoltaic modules, making it uneconomical and energy-intensive. It also produces toxic chlorine-containing gases (such as HCl) and coke (yield >10%), requiring an exhaust gas purification system. Furthermore, the high temperature causes the photovoltaic glass to soften and deform (softening point ≈720°C), reducing the light transmittance of the recycled glass to below 85%. Solvent methods are generally divided into strong acid / strong base methods and organic solvent treatment methods. The strong acid / strong base method uses highly corrosive reagents such as concentrated sulfuric acid or sodium hydroxide to treat the photovoltaic modules, breaking down the EVA molecular chains through acid hydrolysis or saponification reactions. The reaction produces sulfur- and nitrogen-containing wastewater and organic byproducts (such as sodium acetate), increasing treatment costs and causing environmental pollution. Acids and alkalis attack the photovoltaic glass surface, reducing light transmittance. Furthermore, strong acids and alkalis decompose the TPT backsheet material, reducing the purity of the recycled product. Organic solvent treatment methods typically use organic solvents such as xylene and tetrahydrofuran to peel off the EVA film through swelling. This swelling process is time-consuming and accompanied by the release of volatile organic compounds (VOCs). Furthermore, the organic solvent loss rate per use exceeds 50%, and the energy consumption of recovery distillation is excessive. Both thermal decomposition and solvent methods have significant drawbacks, including high environmental risks (strong acid / alkali, VOC emissions), poor economic efficiency (solvent loss, recovery costs), and complex processes. These issues hinder the industrialization of green photovoltaic module recycling and require further improvement. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for efficiently depolymerizing EVA films of photovoltaic modules based on functionalized ionic liquids, which solves the problem that the existing technology cannot directly process photovoltaic modules containing glass substrates, and the photovoltaic glass and EVA films are difficult to efficiently peel off, are not green and environmentally friendly, and are costly.

[0004] The present invention is achieved through the following technical solutions:

[0005] A method for efficiently depolymerizing an EVA film of a photovoltaic module based on a functionalized ionic liquid, the method comprising the following steps:

[0006] (1) Preparation of functionalized ionic liquid: First, the choline cationic salt is synthesized. Trimethylamine (TMA) and chloroethanol are mixed in a molar ratio of 1:1.0-1.5, dissolved in anhydrous ethanol, and stirred at 50-80 °C for 36-60 h under nitrogen protection. The reaction solution is subjected to rotary evaporation to remove the solvent, and the residue is recrystallized from acetone / ether (volume ratio 1:3-5) to obtain white crystals of [Choline]Cl. Then, the functionalization design of the anion is carried out: metal halide powder and the obtained white crystals of [Choline]Cl are added to a reactor, stirred at 100-150 °C, preferably 120 °C, in a molten state for 1-3 h, preferably 2 h, to obtain the desired functionalized ionic liquid, named choline chloride-metal chloride ionic liquid, and then an appropriate amount of ethylene glycol is added to control the viscosity at 50-200 mPa·s (25 °C).

[0007] (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the functionalized ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are started simultaneously, wherein the ultrasonic power is set to the range of 200~500 W, preferably 400-500 W, and the fixed frequency of 40 kHz is selected. The heating temperature is controlled in the range of 80~120 ℃, preferably 100-120 ℃, and the treatment time is set to 1~3 h, preferably 2-3 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out. The purity of the glass is tested to achieve photovoltaic glass regeneration and recover the functionalized ionic liquid catalyst at the same time.

[0008] Preferably, the molar ratio of trimethylamine (TMA) to chloroethanol used in step (1) is 1:1.2.

[0009] Preferably, the synthesis temperature of the choline cation in step (1) is 60° C., and the stirring time is 48 h.

[0010] Preferably, the volume ratio of acetone to ether in the solvent used for recrystallization in step (1) is 1:4.

[0011] Preferably, the metal halide in step (1) is one of ZnCl2, AlCl3, and FeCl3.

[0012] Preferably, the molar ratio of the metal halide powder in step (1) to the obtained white crystals is 1:1 to 3:1.

[0013] The beneficial effects of the present invention are as follows:

[0014] (1) Functionalized ionic liquid choline chloride-metal chloride ionic liquid is used to replace traditional strong acid / alkali or organic solvents to achieve depolymerization under neutral / mild conditions, eliminating volatile organic compounds (VOCs) and sulfur / nitrogen-containing wastewater pollution. The degradation products are low-toxic and controllable, avoiding the formation of chlorine-containing gases (such as HCl) and coke. At the same time, choline compounds have good biodegradability and significantly improve environmental friendliness; overcoming the problems of high energy consumption and serious pollution of traditional pyrolysis methods;

[0015] (2) Through the directional catalysis of metal halide anions in choline chloride-metal chloride ionic liquids and the synergistic effect of ultrasound and heat, the EVA molecular chains are efficiently broken at low temperatures of 80-120°C, the depolymerization time is shortened to within 3 hours, and the photovoltaic glass substrate is completely retained. The depolymerization efficiency and glass recycling quality are greatly improved, thereby achieving efficient and environmentally friendly separation of photovoltaic glass and EVA film. This method solves the problems of low depolymerization efficiency and difficult regeneration of EVA by existing ionic liquids, as well as the inability to directly treat photovoltaic modules containing glass substrates;

[0016] (3) The functionalized ionic liquid catalyst (choline chloride-metal chloride ionic liquid) can restore its catalytic activity by simple centrifugal separation and regeneration, which significantly reduces the cost of use and has high practical value.

[0017] (4) The present invention can directly process the entire photovoltaic module, eliminating the EVA stripping process and increasing the depolymerization efficiency to over 98%.

[0018] In summary, the present invention achieves neutral / mild depolymerization through the directional catalysis of metal halide anions in the choline chloride-metal chloride ionic liquid and the synergistic effect of ultrasound and heat, and the depolymerization time is shortened to within 3 hours, while the photovoltaic glass substrate is completely retained, thereby achieving efficient and environmentally friendly separation of the photovoltaic glass and the EVA film, without VOCs emissions, and the choline chloride-metal chloride ionic liquid catalyst is recyclable and low in cost. DETAILED DESCRIPTION

[0019] The following is a further description of the present invention, but not a limitation of the present invention.

[0020] Example 1: A method for efficient depolymerization of photovoltaic module EVA film catalyzed by functionalized ionic liquid

[0021] The following steps are involved:

[0022] (1) Preparation of functionalized ionic liquids: First, the choline cationic salt was synthesized. Trimethylamine (TMA) and chloroethanol were mixed in a molar ratio of 1:1.2, dissolved in anhydrous ethanol, and stirred at 60°C under nitrogen for 48 h. The reaction solution was rotary evaporated to remove the solvent, and the residue was recrystallized from acetone / ether (volume ratio 1:4) to obtain white crystals of [Choline]Cl. Then, the anion functionalization design was carried out: ZnCl2 powder and the obtained cationic salt ([Choline]Cl) were added to the reactor in a molar ratio of 2:1. The mixture was stirred in a molten state at 120°C for 2 h to obtain the desired ionic liquid catalyst [Choline][ZnCl3]. An appropriate amount of ethylene glycol was then added to control the viscosity to 50-200 mPa·s (25°C).

[0023] (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the functionalized ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are turned on simultaneously, wherein: the ultrasonic power is set to 400 W, the fixed frequency is 40 kHz, the heating temperature is controlled at 100 °C, and the treatment time is set to 2 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out. The purity of the glass is tested to achieve photovoltaic glass regeneration and recover the ionic liquid catalyst at the same time.

[0024] After testing, the EVA decomposition rate reached 99.2%, achieving efficient and green separation of the glass substrate and the EVA film. See Table 1 for details.

[0025] Comparative Example 1:

[0026] Refer to Example 1, except that no functionalization design of the anion is performed in step (1).

[0027] The following steps are involved:

[0028] (1) Preparation of ionic liquid: Trimethylamine (TMA) and chloroethanol were mixed in a molar ratio of 1:1.2, dissolved in anhydrous ethanol, and stirred at 60°C under nitrogen for 48 h. The reaction solution was rotary evaporated to remove the solvent, and the residue was recrystallized from acetone / ether (volume ratio 1:4) to obtain white crystals of [Choline]Cl. An appropriate amount of ethylene glycol was then added to control the viscosity to 50-200 mPa·s (25°C).

[0029] (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are turned on simultaneously, wherein: the ultrasonic power is set to 400 W, the frequency is fixed at 40 kHz, the heating temperature is controlled at 100 °C, and the treatment time is set to 2 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out, and the purity of the glass is tested.

[0030] After testing, the EVA decomposition rate was 62.2%.

[0031] Example 2: A method for efficient depolymerization of photovoltaic module EVA film catalyzed by functionalized ionic liquid

[0032] Refer to Example 1, except that: in step (1), ZnCl2 powder is replaced by AlCl3 powder.

[0033] The following steps are involved:

[0034] (1) Preparation of functionalized ionic liquids: First, the choline cationic salt was synthesized. Trimethylamine (TMA) and chloroethanol were mixed in a molar ratio of 1:1.2, dissolved in anhydrous ethanol, and stirred at 60°C for 48 h under nitrogen protection. The reaction solution was rotary evaporated to remove the solvent, and the residue was recrystallized from acetone / ether (volume ratio 1:4) to obtain white crystals of [Choline]Cl. Then, the functionalization of the anion was carried out: AlCl3 powder and the obtained cationic salt ([Choline]Cl) were added to the reactor in a molar ratio of 2:1. The mixture was stirred in a molten state at 120°C for 2 h to obtain the desired ionic liquid catalyst [Choline][AlCl4]. An appropriate amount of ethylene glycol was then added to control the viscosity to 50-200 mPa·s (25°C).

[0035] (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the functionalized ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are turned on simultaneously, wherein: the ultrasonic power is set to 400 W, the fixed frequency is 40 kHz, the heating temperature is controlled at 100 °C, and the treatment time is set to 2 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out. The purity of the glass is tested to achieve photovoltaic glass regeneration and recover the ionic liquid catalyst at the same time.

[0036] After testing, the EVA decomposition rate reached 98.4%, achieving efficient and green separation of the glass substrate and the EVA film. See Table 1 for details.

[0037] Example 3: A method for efficient depolymerization of photovoltaic module EVA film catalyzed by functionalized ionic liquid

[0038] Refer to Example 1, except that: in step (1), ZnCl2 powder is replaced by FeCl3 powder.

[0039] The following steps are involved:

[0040] (1) Preparation of functionalized ionic liquids: First, the choline cationic salt was synthesized. Trimethylamine (TMA) and chloroethanol were mixed in a molar ratio of 1:1.2, dissolved in anhydrous ethanol, and stirred at 60°C under nitrogen for 48 h. The reaction solution was rotary evaporated to remove the solvent, and the residue was recrystallized from acetone / ether (volume ratio 1:4) to obtain white crystals of [Choline]Cl. Then, the anion functionalization design was carried out: FeCl3 powder and the obtained cationic salt ([Choline]Cl) were added to the reactor in a molar ratio of 2:1. The mixture was stirred in a molten state at 120°C for 2 h to obtain the desired ionic liquid catalyst [Choline][FeCl4]. An appropriate amount of ethylene glycol was then added to control the viscosity to 50-200 mPa·s (25°C).

[0041] (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the functionalized ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are turned on simultaneously, wherein: the ultrasonic power is set to 400 W, the fixed frequency is 40 kHz, the heating temperature is controlled at 100 °C, and the treatment time is set to 2 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out. The purity of the glass is tested to achieve photovoltaic glass regeneration and recover the ionic liquid catalyst at the same time.

[0042] After testing, the EVA decomposition rate reached 98.0%, achieving efficient and green separation of the glass substrate and the EVA film. See Table 1 for details.

[0043] Example 4: A method for efficient depolymerization of photovoltaic module EVA film catalyzed by functionalized ionic liquid

[0044] Refer to Example 1, except that in step (1), ZnCl2 powder and the obtained cationic salt ([Choline]Cl) were added to the reactor at a molar ratio of 1:1.

[0045] The following steps are involved:

[0046] (1) Preparation of functionalized ionic liquids: First, the choline cationic salt was synthesized. Trimethylamine (TMA) and chloroethanol were mixed in a molar ratio of 1:1.2, dissolved in anhydrous ethanol, and stirred at 60°C under nitrogen for 48 h. The reaction solution was rotary evaporated to remove the solvent, and the residue was recrystallized from acetone / ether (volume ratio 1:4) to obtain white crystals of [Choline]Cl. Then, the anion functionalization design was carried out: ZnCl2 powder and the obtained cationic salt ([Choline]Cl) were added to the reactor in a molar ratio of 1:1. The mixture was stirred in a molten state at 120°C for 2 h to obtain the desired ionic liquid catalyst [Choline][ZnCl3]. An appropriate amount of ethylene glycol was then added to control the viscosity to 50-200 mPa·s (25°C).

[0047] (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the functionalized ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are turned on simultaneously, wherein: the ultrasonic power is set to 400 W, the fixed frequency is 40 kHz, the heating temperature is controlled at 100 °C, and the treatment time is set to 2 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out. The purity of the glass is tested to achieve photovoltaic glass regeneration and recover the ionic liquid catalyst at the same time.

[0048] After testing, the EVA decomposition rate reached 96.1%, achieving efficient and green separation of the glass substrate and the EVA film. See Table 1 for details.

[0049] Example 5: A method for efficient depolymerization of photovoltaic module EVA film catalyzed by functionalized ionic liquid

[0050] Refer to Example 1, except that in step (1), ZnCl2 powder and the obtained cationic salt ([Choline]Cl) were added to the reactor at a molar ratio of 3:1.

[0051] The following steps are involved:

[0052] (1) Preparation of functionalized ionic liquids: First, the choline cationic salt was synthesized. Trimethylamine (TMA) and chloroethanol were mixed in a molar ratio of 1:1.2, dissolved in anhydrous ethanol, and stirred at 60°C under nitrogen for 48 h. The reaction solution was rotary evaporated to remove the solvent, and the residue was recrystallized from acetone / ether (volume ratio 1:4) to obtain white crystals of [Choline]Cl. Then, the anion functionalization design was carried out: ZnCl2 powder and the obtained cationic salt ([Choline]Cl) were added to the reactor in a molar ratio of 3:1. The mixture was stirred in a molten state at 120°C for 2 h to obtain the desired ionic liquid catalyst [Choline][ZnCl3]. An appropriate amount of ethylene glycol was then added to control the viscosity to 50-200 mPa·s (25°C).

[0053] (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the functionalized ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are turned on simultaneously, wherein: the ultrasonic power is set to 400 W, the fixed frequency is 40 kHz, the heating temperature is controlled at 100 °C, and the treatment time is set to 2 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out. The purity of the glass is tested to achieve photovoltaic glass regeneration and recover the ionic liquid catalyst at the same time.

[0054] After testing, the EVA decomposition rate reached 95.9%, achieving efficient and green separation of the glass substrate and the EVA film. See Table 1 for details.

[0055] Example 6: A method for efficient depolymerization of photovoltaic module EVA film catalyzed by functionalized ionic liquid

[0056] Refer to Example 1, except that: the ultrasonic power in step (2) is set to 200 W.

[0057] The following steps are involved:

[0058] (1) Preparation of functionalized ionic liquids: First, the choline cationic salt was synthesized. Trimethylamine (TMA) and chloroethanol were mixed in a molar ratio of 1:1.2, dissolved in anhydrous ethanol, and stirred at 60°C under nitrogen for 48 h. The reaction solution was rotary evaporated to remove the solvent, and the residue was recrystallized from acetone / ether (volume ratio 1:4) to obtain white crystals of [Choline]Cl. Then, the anion functionalization design was carried out: ZnCl2 powder and the obtained cationic salt ([Choline]Cl) were added to the reactor in a molar ratio of 2:1. The mixture was stirred in a molten state at 120°C for 2 h to obtain the desired ionic liquid catalyst [Choline][ZnCl3]. An appropriate amount of ethylene glycol was then added to control the viscosity to 50-200 mPa·s (25°C).

[0059] (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the functionalized ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are turned on simultaneously, wherein: the ultrasonic power is set to 200 W, the fixed frequency is 40 kHz, the heating temperature is controlled at 100 °C, and the treatment time is set to 2 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out. The purity of the glass is tested to achieve photovoltaic glass regeneration and recover the ionic liquid catalyst at the same time.

[0060] After testing, the EVA decomposition rate reached 95.5%, achieving efficient and green separation of the glass substrate and the EVA film. See Table 1 for details.

[0061] Example 7: A method for efficient depolymerization of photovoltaic module EVA film catalyzed by functionalized ionic liquid

[0062] Refer to Example 1, except that: the ultrasonic power in step (2) is set to 500 W.

[0063] The following steps are involved:

[0064] (1) Preparation of functionalized ionic liquids: First, the choline cationic salt was synthesized. Trimethylamine (TMA) and chloroethanol were mixed in a molar ratio of 1:1.2, dissolved in anhydrous ethanol, and stirred at 60°C under nitrogen for 48 h. The reaction solution was rotary evaporated to remove the solvent, and the residue was recrystallized from acetone / ether (volume ratio 1:4) to obtain white crystals of [Choline]Cl. Then, the anion functionalization design was carried out: ZnCl2 powder and the obtained cationic salt ([Choline]Cl) were added to the reactor in a molar ratio of 2:1. The mixture was stirred in a molten state at 120°C for 2 h to obtain the desired ionic liquid catalyst [Choline][ZnCl3]. An appropriate amount of ethylene glycol was then added to control the viscosity to 50-200 mPa·s (25°C).

[0065] (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the functionalized ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are turned on simultaneously, wherein: the ultrasonic power is set to 500 W, the frequency is fixed at 40 kHz, the heating temperature is controlled at 100 °C, and the treatment time is set to 2 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out. The purity of the glass is tested to achieve photovoltaic glass regeneration and recover the ionic liquid catalyst at the same time.

[0066] After testing, the EVA decomposition rate reached 99.1%, achieving efficient and green separation of the glass substrate and the EVA film. See Table 1 for details.

[0067] Example 8: A method for efficient depolymerization of photovoltaic module EVA film catalyzed by functionalized ionic liquid

[0068] Refer to Example 1, except that the heating temperature in step (2) is set to 80°C.

[0069] The following steps are involved:

[0070] (1) Preparation of functionalized ionic liquids: First, the choline cationic salt was synthesized. Trimethylamine (TMA) and chloroethanol were mixed in a molar ratio of 1:1.2, dissolved in anhydrous ethanol, and stirred at 60°C under nitrogen for 48 h. The reaction solution was rotary evaporated to remove the solvent, and the residue was recrystallized from acetone / ether (volume ratio 1:4) to obtain white crystals of [Choline]Cl. Then, the anion functionalization design was carried out: ZnCl2 powder and the obtained cationic salt ([Choline]Cl) were added to the reactor in a molar ratio of 2:1. The mixture was stirred in a molten state at 120°C for 2 h to obtain the desired ionic liquid catalyst [Choline][ZnCl3]. An appropriate amount of ethylene glycol was then added to control the viscosity to 50-200 mPa·s (25°C).

[0071] (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the functionalized ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are turned on simultaneously, wherein: the ultrasonic power is set to 400 W, the fixed frequency is 40 kHz, the heating temperature is controlled at 80 °C, and the treatment time is set to 2 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out. The purity of the glass is tested to achieve photovoltaic glass regeneration and recover the ionic liquid catalyst at the same time.

[0072] After testing, the EVA decomposition rate reached 97.6%, achieving efficient and green separation of the glass substrate and the EVA film. See Table 1 for details.

[0073] Example 9: A method for efficient depolymerization of photovoltaic module EVA film catalyzed by functionalized ionic liquid

[0074] Refer to Example 1, except that the heating temperature in step (2) is set to 120°C.

[0075] The following steps are involved:

[0076] (1) Preparation of functionalized ionic liquids: First, the choline cationic salt was synthesized. Trimethylamine (TMA) and chloroethanol were mixed in a molar ratio of 1:1.2, dissolved in anhydrous ethanol, and stirred at 60°C under nitrogen for 48 h. The reaction solution was rotary evaporated to remove the solvent, and the residue was recrystallized from acetone / ether (volume ratio 1:4) to obtain white crystals of [Choline]Cl. Then, the anion functionalization design was carried out: ZnCl2 powder and the obtained cationic salt ([Choline]Cl) were added to the reactor in a molar ratio of 2:1. The mixture was stirred in a molten state at 120°C for 2 h to obtain the desired ionic liquid catalyst [Choline][ZnCl3]. An appropriate amount of ethylene glycol was then added to control the viscosity to 50-200 mPa·s (25°C).

[0077] (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the functionalized ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are turned on simultaneously, wherein: the ultrasonic power is set to 400 W, the fixed frequency is 40 kHz, the heating temperature is controlled at 120 °C, and the treatment time is set to 2 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out. The purity of the glass is tested to achieve photovoltaic glass regeneration and recover the ionic liquid catalyst at the same time.

[0078] After testing, the EVA decomposition rate reached 99.0%, achieving efficient and green separation of the glass substrate and the EVA film. See Table 1 for details.

[0079] Example 10: A method for efficient depolymerization of photovoltaic module EVA film catalyzed by functionalized ionic liquid

[0080] Refer to Example 1, except that the treatment time in step (2) is 1 h.

[0081] The following steps are involved:

[0082] (1) Preparation of functionalized ionic liquids: First, the choline cationic salt was synthesized. Trimethylamine (TMA) and chloroethanol were mixed in a molar ratio of 1:1.2, dissolved in anhydrous ethanol, and stirred at 60°C under nitrogen for 48 h. The reaction solution was rotary evaporated to remove the solvent, and the residue was recrystallized from acetone / ether (volume ratio 1:4) to obtain white crystals of [Choline]Cl. Then, the anion functionalization design was carried out: ZnCl2 powder and the obtained cationic salt ([Choline]Cl) were added to the reactor in a molar ratio of 2:1. The mixture was stirred in a molten state at 120°C for 2 h to obtain the desired ionic liquid catalyst [Choline][ZnCl3]. An appropriate amount of ethylene glycol was then added to control the viscosity to 50-200 mPa·s (25°C).

[0083] (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the functionalized ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are turned on simultaneously, wherein: the ultrasonic power is set to 400 W, the fixed frequency is 40 kHz, the heating temperature is controlled at 100 °C, and the treatment time is set to 1 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out. The purity of the glass is tested to achieve photovoltaic glass regeneration and recover the ionic liquid catalyst at the same time.

[0084] After testing, the EVA decomposition rate reached 97.4%, achieving efficient and green separation of the glass substrate and the EVA film. See Table 1 for details.

[0085] Example 11: A method for efficient depolymerization of photovoltaic module EVA film catalyzed by functionalized ionic liquid

[0086] Refer to Example 1, except that the treatment time in step (2) is 3 h.

[0087] The following steps are involved:

[0088] (1) Preparation of functionalized ionic liquids: First, the choline cationic salt was synthesized. Trimethylamine (TMA) and chloroethanol were mixed in a molar ratio of 1:1.2, dissolved in anhydrous ethanol, and stirred at 60°C under nitrogen for 48 h. The reaction solution was rotary evaporated to remove the solvent, and the residue was recrystallized from acetone / ether (volume ratio 1:4) to obtain white crystals of [Choline]Cl. Then, the anion functionalization design was carried out: ZnCl2 powder and the obtained cationic salt ([Choline]Cl) were added to the reactor in a molar ratio of 2:1. The mixture was stirred in a molten state at 120°C for 2 h to obtain the desired ionic liquid catalyst [Choline][ZnCl3]. An appropriate amount of ethylene glycol was then added to control the viscosity to 50-200 mPa·s (25°C).

[0089] (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the functionalized ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are turned on simultaneously, wherein: the ultrasonic power is set to 400 W, the fixed frequency is 40 kHz, the heating temperature is controlled at 100 °C, and the treatment time is set to 3 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out. The purity of the glass is tested to achieve photovoltaic glass regeneration and recover the ionic liquid catalyst at the same time.

[0090] Table 1

[0091]

[0092] After testing, the EVA decomposition rate reached 99.1%, achieving efficient and green separation of the glass substrate and the EVA film. See Table 1 for details.

Claims

1. A method for efficiently depolymerizing EVA films of photovoltaic modules based on functionalized ionic liquids, characterized in that: The method comprises the following steps: (1) Preparation of functionalized ionic liquid: trimethylamine and chloroethanol were mixed in a molar ratio of 1:1.0~1.5, dissolved in anhydrous ethanol, and stirred at 50~80℃ for 36~60h under nitrogen protection. The reaction solution was evaporated to remove the solvent, and the residue was recrystallized with a mixed solvent of acetone and ether in a volume ratio of 1:3~5 to obtain white crystals of [Choline]Cl. Then, metal halide powder and the obtained white crystals of [Choline]Cl were added to the reactor and stirred in a molten state at 100~150℃ for 1~3h to obtain the desired functionalized ionic liquid, named choline chloride-metal chloride ionic liquid. Then, an appropriate amount of ethylene glycol was added to control its viscosity at 50~200 mPa·s at 25℃. (2) EVA film depolymerization process: The photovoltaic laminated glass component containing the EVA adhesive layer is immersed in the functionalized ionic liquid obtained in step (1) to ensure that the component is completely immersed in the liquid phase system; the ultrasonic treatment device and the heating temperature control system are turned on simultaneously, wherein the ultrasonic power is set to the range of 200~500 W, the fixed frequency of 40 kHz is selected, the heating temperature is controlled in the range of 80~120 ℃, and the treatment time is set to 1~3 h. After the reaction is completed, the intact glass substrate is separated from the reaction medium, and subsequent cleaning treatment is carried out. The purity of the glass is tested to achieve photovoltaic glass regeneration and recover the functionalized ionic liquid catalyst at the same time.

2. The method according to claim 1, characterized in that The molar ratio of trimethylamine to chloroethanol used in step (1) is 1:1.

2.

3. The method according to claim 1, characterized in that Step (1) trimethylamine and chloroethanol are mixed in a molar ratio of 1:1.0-1.5, dissolved in anhydrous ethanol, and stirred at 60°C under nitrogen protection for 48 h.

4. The method according to claim 1, wherein The volume ratio of acetone to ether in the solvent used for recrystallization in step (1) is 1:

4.

5. The method according to claim 1, wherein The metal halide in step (1) is one of ZnCl2, AlCl3, and FeCl3.

6. The method according to claim 1, wherein The molar ratio of the metal halide powder in step (1) to the obtained white crystals is 1:1 to 3:

1.

7. The method according to claim 1, characterized in that Step (1) Metal halide powder and the obtained white crystal [Choline]Cl are added to a reactor and stirred at 120°C in a molten state for 2 h to obtain the desired functionalized ionic liquid.

8. The method according to claim 1, characterized in that In step (2), the ultrasonic power is set to 400-500 W, the heating temperature is controlled at 100-120 °C, and the treatment time is set to 2-3 h.

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