Process for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent

Abstract

The application discloses a method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent, belongs to the field of diluent recovery, and aims at the technical problems that the recovery purity, recovery rate and long-period operation stability of PM and PGMEA in waste diluent need to be further improved, and specifically comprises the following steps: after pretreatment, the waste diluent is transported to a fixed complex separation bed filled with non-halogen hydrogen bond acceptor complex materials, so that propylene glycol methyl ether and water are complexed with the non-halogen hydrogen bond acceptor complex materials and are retained, the non-halogen hydrogen bond acceptor complex materials are constructed, propylene glycol methyl ether acetate is preferentially flowed out, and three-stage vacuum pyrolysis complexing is performed to realize segmented release and material regeneration, so that the high-purity recovery of propylene glycol methyl ether or propylene glycol methyl ether acetate is ensured, and the high recovery rate and long-period operation stability are maintained.

Description

Technical Field

[0001] This invention relates to the field of diluent recovery, and more specifically to a method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluents. Background Technology

[0002] Propylene glycol methyl ether (PM) and propylene glycol methyl ether acetate (PGMEA) are commonly used organic solvents in the semiconductor, display panel, photoresist, and precision electronic chemicals industries. They are characterized by strong dissolving power, moderate evaporation rate, and good compatibility with various resins and additives. They are often used in processes such as photoresist dilution, edge washing, substrate back cleaning, coating equipment cleaning, and pipeline replacement. During the operation of the above processes, a large amount of waste diluent containing propylene glycol methyl ether, propylene glycol methyl ether acetate, water, photoresist resin, photoacid generator, pigments, surfactants, particulate matter, and other organic impurities is generated.

[0003] Currently, the main methods for recovering waste liquid containing propylene glycol methyl ether (PME) and propylene glycol methyl ether acetate include filtration, sedimentation, adsorption, extraction, and distillation. Simple filtration or sedimentation is primarily used to remove solid particles and some colloidal impurities, but it is difficult to achieve effective separation between the target solvents. While adsorption can remove some color, resin, and high-boiling impurities, conventional adsorbents have limited selectivity for PME, propylene glycol methyl ether acetate, and water, and adsorbent regeneration is difficult. Long-term operation can easily lead to pore blockage and adsorption performance degradation. Furthermore, there is a certain degree of mutual entrainment between PME, propylene glycol methyl ether acetate, and water in the waste diluent. The waste liquid also contains resins, colloids, and high-boiling heavy components derived from photoresist, which can easily lead to increased energy consumption in the distillation process, increased pollution within the column, and decreased product purity. Therefore, the recovery purity, recovery rate, and long-term operational stability of PM and PMEA in the waste diluent need further improvement.

[0004] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluents, in order to solve the technical problem that the recovery purity, recovery rate and long-term operational stability of PM and PGMEA in waste diluents in the prior art need to be further improved.

[0006] The objective of this invention can be achieved through the following technical solution: a method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent, comprising the following steps: S1. Pre-treat the waste diluent to remove solid particles, colloidal resins, and heavy components with boiling points higher than propylene glycol methyl ether acetate, to obtain a pre-treated solution. S2. The pretreatment solution enters the immobilized complexation separation bed filled with non-halogen hydrogen bond acceptor complexing material, so that propylene glycol methyl ether and water undergo complexation with the non-halogen hydrogen bond acceptor complexing material and are retained, so that propylene glycol methyl ether acetate flows out preferentially relative to propylene glycol methyl ether, and propylene glycol methyl ether acetate enriched solution is collected. S3. When the mass ratio of propylene glycol methyl ether to propylene glycol methyl ether acetate in the outlet liquid of the immobilized complexing separation bed reaches 20-30% of the mass ratio of propylene glycol methyl ether to propylene glycol methyl ether acetate in the inlet liquid of the immobilized complexing separation bed, stop the flow of pretreatment liquid, and use part of the propylene glycol methyl ether acetate enrichment liquid as replacement washing liquid to pass through the immobilized complexing separation bed to replace the uncomplexed propylene glycol methyl ether acetate entrained in the immobilized complexing separation bed, and collect the replacement washing liquid. S4. The immobilized complex separation bed after replacement washing is subjected to three stages of decomposition and pyrolysis in a first decomposition stage, a second decomposition stage, and a third cooling and reuse stage. In the first decomposition stage, propylene glycol methyl ether acetate enriched solution is collected. In the second decomposition stage, propylene glycol methyl ether desorbate is collected. In the third cooling and reuse stage, the fixed bed is switched back to the complex separation state. S5. The propylene glycol methyl ether acetate enrichment solution and the displacement washing solution are subjected to a first purification treatment to obtain the propylene glycol methyl ether acetate product. S6. The propylene glycol methyl ether desorption solution is subjected to a second purification treatment to obtain the propylene glycol methyl ether product.

[0007] Furthermore, the waste diluent originates from photoresist dilution, edge washing, substrate back cleaning, coating equipment cleaning, or pipeline replacement processes, and contains propylene glycol methyl ether, propylene glycol methyl ether acetate, water, and organic impurities from photoresist sources; the waste diluent comprises, by mass percentage: 1-80% propylene glycol methyl ether, 10-98% propylene glycol methyl ether acetate, 0.01-15% water, 0.001-20% organic impurities from photoresist sources, and 0-40% other organic solvents.

[0008] Furthermore, the pretreatment operation includes: mixing waste diluent and diatomaceous earth at a liquid-to-solid ratio of 10:1, stirring at room temperature for 20-30 minutes, filtering, and obtaining a pretreated solution.

[0009] Furthermore, the non-halogen hydrogen bond acceptor complex material is obtained by the following steps: A1. Mix N-vinylpyrrolidone, N,N-dimethylacrylamide, ethylene glycol dimethacrylate, azobisisobutyronitrile and toluene and stir until the system is dissolved to obtain a polymerization solution; A2. Place the unsaturated modified porous silicon in a vacuum impregnation vessel, evacuate to -0.08 to -0.095 MPa, and maintain for 10-30 minutes to remove air from the pores. Then add the polymerization liquid to the vacuum impregnation vessel, stir, heat the reaction system to 80-90℃, and keep it at that temperature for 2-3 hours. After post-treatment, a non-halogen hydrogen bond acceptor complex material is obtained.

[0010] Furthermore, in step A1, the ratio of N-vinylpyrrolidone, N,N-dimethylacrylamide, ethylene glycol dimethacrylate, azobisisobutyronitrile, and toluene is 70-80g:50-60g:7-8g:0.6-0.8g:400mL.

[0011] Furthermore, in step A2, the ratio of the unsaturated modified porous silica to the polymerization liquid is 10g:8-10mL. The post-treatment includes: after the reaction is complete, the reaction system is cooled to room temperature, washed 5 times with toluene at 60-70℃, filtered, and the filter cake is transferred to a drying oven at 70-80℃ and dried to constant weight to obtain a non-halogen hydrogen bond acceptor complex material.

[0012] Furthermore, the unsaturated modified porous silicon is obtained by the following steps: B1. Mix porous silica and nitric acid solution, raise the reaction system to 60-70℃, keep it at the temperature and stir for 3-5 hours, and then perform post-treatment to obtain acid-activated porous silica. B2. Mix acid-activated porous silica, methacryloxypropyltrimethoxysilane and anhydrous ethanol, and ultrasonically disperse for 30-50 min. Heat the reaction system to 50-60℃, add acetic acid solution to the reaction system, keep the reaction at this temperature for 60-80 min, and then perform post-treatment to obtain unsaturated modified porous silica.

[0013] Further, in step B1, the solid-liquid ratio of the porous silica and the nitric acid solution is 1:10. The nitric acid solution is composed of 2-3 mol / L nitric acid and 10 wt% hydrogen peroxide in a volume ratio of 7-8:1. The post-treatment includes: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral and then dried, the filter cake is transferred to a drying oven at a temperature of 70-80℃ and dried to constant weight to obtain acid-activated porous silica.

[0014] Further, in step B2, the ratio of acid-activated porous silica, methacryloxypropyltrimethoxysilane, anhydrous ethanol, and acetic acid solution is 10g:0.9-1.1g:100mL:10mL, and the concentration of the acetic acid solution is 1-2mol / L. The post-treatment includes: after the reaction is complete, the reaction system is cooled to room temperature, filtered, the filter cake is washed with purified water until neutral, dried, and the filter cake is transferred to a drying oven at 70-80℃ and dried to constant weight to obtain unsaturated modified porous silica.

[0015] Furthermore, in step S3, the feed temperature of the immobilized complexing separation bed is 35-45℃, and the space velocity of the pretreatment solution entering the immobilized complexing separation bed is 1-2 h⁻¹. -1 The operating pressure is 0.3-0.5 MPa; Furthermore, in step S4, the temperature of the first decomplexing stage is 70-80℃, the operating pressure is 25-30kPa, the nitrogen purging rate is 80-100NL / (kg packing·h), and the purging time is 2-3h; the temperature of the second decomplexing stage is 100-120℃, the operating pressure is 1-10kPa, the nitrogen purging rate is 80-100NL / (kg packing·h), and the purging time is 3-5h; the temperature of the third cooling and reuse stage is 30-45℃, the operating pressure is atmospheric pressure, the nitrogen purging rate is 80-100NL / (kg packing·h), and the purging time is 3-5h.

[0016] Further, the first refining process includes: combining the propylene glycol methyl ether acetate enriched solution collected from the immobilized complex separation bed with the displacement washing effluent, filtering it through a 1μm filter, and sending it to a light component removal and dehydration tower. The light component containing propylene glycol methyl ether, water, and low-boiling substances is collected from the top of the tower, and crude propylene glycol methyl ether acetate is obtained from the bottom of the tower. The crude propylene glycol methyl ether acetate enters the propylene glycol methyl ether acetate product tower, and the propylene glycol methyl ether acetate product is collected from the side stream. The high-boiling residual liquid is discharged from the bottom of the tower.

[0017] Furthermore, the light-light dehydration tower has 35-50 theoretical plates, an operating pressure of 40-60 kPa, a top temperature of 80-90℃, a bottom temperature of 100-120℃, a reflux ratio of 3-5, and the feed position is at the 20th theoretical plate from the top of the tower; the product tower has 60-70 theoretical plates, an operating pressure of 20-40 kPa, a top temperature of 80-100℃, a bottom temperature of 115-135℃, a reflux ratio of 5-7, and the feed position is at the 50th theoretical plate from the top of the tower. Propylene glycol methyl ether acetate product is collected from a side stream near the 40th theoretical plate from the top of the tower.

[0018] Furthermore, the second refining process includes: feeding the propylene glycol methyl ether-containing desorbate obtained from the second decomplexing stage into a propylene glycol methyl ether dehydration and light-removal column; collecting the water-containing pre-distillate from the top of the column; obtaining a low-water crude propylene glycol methyl ether from the bottom of the column; the low-water crude propylene glycol methyl ether entering the propylene glycol methyl ether product column; collecting the top of the column; first, cutting off the pre-distillate from the top of the column; collecting the propylene glycol methyl ether product distillate after the water content in the current distillate is below 500 ppm; and returning the propylene glycol methyl ether acetate enriched solution obtained from the bottom of the column to the propylene glycol methyl ether acetate refining process.

[0019] Furthermore, the theoretical number of trays in the propylene glycol methyl ether dehydration and light ether removal tower is 40-50, the operating pressure is 60-80 kPa, the top temperature is 80-90℃, the bottom temperature is 100-110℃, the reflux ratio is 3-5, and the feed position is at the 20th theoretical tray from the top of the tower; the theoretical number of trays in the propylene glycol methyl ether product tower is 70-80, the operating pressure is 40-60 kPa, the top temperature is 95-105℃, the bottom temperature is 120-130℃, the reflux ratio is 5-6, and the feed position is at the 20th theoretical tray from the top of the tower.

[0020] The present invention has the following beneficial effects: 1. This invention constructs an immobilized non-halogenated hydrogen bond acceptor complex material by acid-activated porous silica, unsaturated silane coupling modification, and in-situ crosslinking polymerization within the pores. The pyrrolidone carbonyl and tertiary amide carbonyl groups in the non-halogenated hydrogen bond acceptor complex material act as hydrogen bond acceptors, forming reversible hydrogen bond complexes with the hydroxyl groups in propylene glycol methyl ether molecules and water molecules. Propylene glycol methyl ether acetate, lacking hydroxyl hydrogen, exhibits weaker complexation with the aforementioned hydrogen bond acceptor sites. When waste diluent passes through the immobilized complex separation bed, propylene glycol methyl ether and water are preferentially retained, while propylene glycol methyl ether acetate preferentially flows out, achieving selective separation based on differences in intermolecular hydrogen bonding. This front-end complex separation reduces the degree of entrainment of propylene glycol methyl ether, water, and propylene glycol methyl ether acetate during subsequent distillation, increasing the mass fraction of recovered propylene glycol methyl ether and recovered propylene glycol methyl ether acetate, thereby improving the purity and utilization value of the recovered solvent.

[0021] 2. This invention also increases the number of silanol groups on the porous silicon surface and cleans the pores through acid activation, providing a reaction basis for the stable grafting of silane coupling agents. Furthermore, unsaturated modification allows the subsequent polymerized functional layer to be covalently fixed on the inorganic porous silicon framework, preventing the functional layer from existing only in physical adsorption and being lost during solvent rinsing or thermal desorption. Vacuum impregnation and in-situ crosslinking polymerization within the pores ensure that hydrogen bond acceptor sites are uniformly distributed within the porous silicon pores, while the crosslinking structure reduces the risk of swelling, migration, and detachment of the polymerized layer. Waste diluent is pretreated with diatomaceous earth before entering the fixed bed to remove solid particles, colloidal resin, and high-boiling-point components, reducing the coverage or blockage of pores and complexation sites by organic impurities from the photoresist source. The non-halogenated hydrogen bond acceptor complexing material works in conjunction with the pretreatment steps, ensuring that the complexing material maintains effective pores and accessible hydrogen bond acceptor sites during long-term operation. This results in the maintenance of the recovery rate of propylene glycol methyl ether and recovered propylene glycol methyl ether acetate after 100 hours of operation, demonstrating good stability for recycling.

[0022] 3. This invention further utilizes a fixed-bed system to complete the complexation separation. A portion of the propylene glycol methyl ether acetate enrichment solution is then introduced into the fixed bed as a replacement washing solution. This displaces the uncomplexed propylene glycol methyl ether acetate entrained in the bed voids, preventing this portion from contaminating the propylene glycol methyl ether desorption solution in the subsequent decomplexation stage. This improves the recovery rate of propylene glycol methyl ether acetate and reduces the propylene glycol methyl ether purification load. Subsequently, a three-stage vacuum pyrolysis complexation method is employed. The first stage releases the complexed propylene glycol methyl ether acetate under relatively mild conditions. The weakly adsorbed or entrained propylene glycol methyl ether acetate undergoes a second stage at higher temperature and lower pressure to disrupt the complexation between propylene glycol methyl ether and hydrogen bond acceptor sites, resulting in concentrated desorption of propylene glycol methyl ether. The third stage restores the bed's complexation capacity through cooling and nitrogen purging. This segmented regeneration method utilizes the reversibility of hydrogen bond complexation, avoiding the mixing of propylene glycol methyl ether and propylene glycol methyl ether acetate caused by single-stage desorption, and also avoiding material aging due to excessive heat treatment, thereby reducing the loss of target components and improving the overall recovery rate. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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] In this invention, the porous silica has a particle size of 0.5-0.8 mm, an average pore size of 15-20 nm, and a pore volume of 0.9 mL / g.

[0025] Example 1 This embodiment provides a method for preparing a non-halogen hydrogen bond acceptor complex material, which specifically includes the following steps: Step 1: Preparation of acid-activated porous silicon 2 mol / L nitric acid and 10 wt% hydrogen peroxide were mixed evenly at a volume ratio of 7:1 to obtain a nitric acid solution; Porous silica and nitric acid solution were added to a reaction flask at a solid-liquid ratio of 1:10 and stirred. The reaction flask was heated to 60°C and stirred for 3 hours. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed with purified water until neutral and then dried. The filter cake was transferred to a drying oven at 70°C and dried to constant weight to obtain acid-activated porous silica.

[0026] During the reaction, the porous silica surface is cleaned, oxidized, and hydroxylated by an oxidizing acidic system composed of nitric acid and hydrogen peroxide. This enhances the active sites on the material surface and makes it easier for the subsequent polymer layer to be stably fixed in the pores. This is beneficial to improving the material's complexation capacity for propylene glycol methyl ether and water, and improving the stability of the recovery rate after long-term operation.

[0027] Step 2: Preparation of unsaturated modified porous silicon Weigh out 100g of acid-activated porous silica, 9g of methacryloyloxypropyltrimethoxysilane, and 1000mL of anhydrous ethanol and add them to a reaction flask. Disperse the mixture by sonication for 30min. Fix the reaction flask on an iron stand with a mechanical stirrer. Heat the reaction flask to 50℃ and add 100mL of 1mol / L acetic acid solution. Keep the reaction at this temperature for 60min. Cool the reaction flask to room temperature and filter. Wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 70℃ and dry it to constant weight to obtain unsaturated modified porous silica.

[0028] During the reaction, methacryloyloxypropyltrimethoxysilane first undergoes hydrolysis in the presence of ethanol and acetic acid aqueous solution, and its trimethoxysilane group is gradually converted into silanol. Then, the silanol reacts with the silanol on the acid-activated porous silicon surface to form a stable Si-O-Si covalent bond, thereby grafting the unsaturated group containing methacryloyloxy onto the porous silicon surface and the inner wall of the pores, introducing double bond anchoring sites that can participate in free radical polymerization on the inorganic porous silicon framework.

[0029] Step 3: Preparation of non-halogen hydrogen bond acceptor complex materials N-vinylpyrrolidone, N,N-dimethylacrylamide, ethylene glycol dimethacrylate, azobisisobutyronitrile and toluene were mixed and stirred until dissolved in a ratio of 70g:50g:7g:0.6g:400mL to obtain a polymerization solution. Weigh 500g of unsaturated modified porous silica and place it in a vacuum impregnation vessel. Evacuate the vessel to -0.08MPa and maintain the pressure for 10min to remove air from the pores. Then add 400mL of polymerization solution to the vacuum impregnation vessel and mix thoroughly. Heat the vacuum impregnation vessel to 80℃ and maintain the temperature for 2h. Cool the vacuum impregnation vessel to room temperature, wash it 5 times with toluene at 60℃, and then filter it. Transfer the filter cake to a drying oven at 70℃ and dry it to constant weight to obtain a non-halogen hydrogen bond acceptor complex material.

[0030] During the reaction, N-vinylpyrrolidone, N,N-dimethylacrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile (AIB) jointly form a polymerization system. AIB decomposes to generate free radicals, which initiate free radical polymerization of the unsaturated double bonds in N-vinylpyrrolidone, N,N-dimethylacrylamide, and ethylene glycol dimethacrylate. Simultaneously, the methacryloyloxy groups grafted onto the porous silica surface in the previous step also participate in the polymerization reaction, fixing the polymer network to the inner walls of the porous silica channels. Ethylene glycol dimethacrylate acts as a crosslinking agent, forming a crosslinked structure between the polymer chains, preventing excessive swelling or solvent washing of the polymer layer. Vacuum impregnation removes air from the porous silica channels, allowing the polymerization liquid to fully enter the pores, thus ensuring that hydrogen bond acceptor sites are distributed not only on the outer surface of the particles but also within the internal pores, improving utilization efficiency.

[0031] N-vinylpyrrolidone contains a pyrrolidone carbonyl group, and N,N-dimethylacrylamide contains a tertiary amide carbonyl group. Both carbonyl groups can act as hydrogen bond acceptors, forming reversible hydrogen bonds with the hydroxyl hydrogen in propylene glycol methyl ether and water molecules. However, propylene glycol methyl ether acetate mainly contains ester groups and lacks hydroxyl hydrogen, making it difficult to form hydrogen bond complexes of equal strength with the aforementioned carbonyl sites. Therefore, it experiences weaker retention in the fixed bed and is more likely to preferentially elute. This utilizes the difference in hydrogen bond strength between PM, PGMEA, and water to achieve selective retention of PM and water, and preferential enrichment of PGMEA. Effective retention of PM and water at the front end reduces the subsequent distillation load of PGMEA, increasing the purity of the PGMEA product. If PM can be released in a concentrated manner during the second decomplexing stage, the impurity entrainment in the PM purification route is reduced, and the PM product mass fraction also increases.

[0032] Example 2 This embodiment provides a method for preparing a non-halogen hydrogen bond acceptor complex material, which specifically includes the following steps: Step 1: Preparation of acid-activated porous silicon Mix 2.5 mol / L nitric acid and 10 wt% hydrogen peroxide at a volume ratio of 7.5:1 to obtain a nitric acid solution. Porous silica and nitric acid solution were added to a reaction flask at a solid-liquid ratio of 1:10 and stirred. The reaction flask was heated to 65°C and stirred for 4 hours. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed with purified water until neutral and then dried. The filter cake was transferred to a drying oven at 75°C and dried to constant weight to obtain acid-activated porous silica.

[0033] Step 2: Preparation of unsaturated modified porous silicon Weigh out 100g of acid-activated porous silica, 10g of methacryloyloxypropyltrimethoxysilane, and 1000mL of anhydrous ethanol and add them to a reaction flask. Disperse the mixture by sonication for 40min. Fix the reaction flask on an iron stand with a mechanical stirrer. Heat the reaction flask to 55℃ and add 100mL of 1.5mol / L acetic acid solution. Keep the reaction at this temperature for 70min. Cool the reaction flask to room temperature and filter. Wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 75℃ and dry it to constant weight to obtain unsaturated modified porous silica.

[0034] Step 3: Preparation of non-halogen hydrogen bond acceptor complex materials N-vinylpyrrolidone, N,N-dimethylacrylamide, ethylene glycol dimethacrylate, azobisisobutyronitrile and toluene were mixed and stirred until dissolved in a ratio of 75g:55g:7.5g:0.7g:400mL to obtain a polymerization solution. Weigh 500g of unsaturated modified porous silica and place it in a vacuum impregnation vessel. Evacuate the vessel to -0.09MPa and maintain the pressure for 20min to remove air from the pores. Then add 450mL of polymerization solution to the vacuum impregnation vessel and mix thoroughly. Heat the vacuum impregnation vessel to 85℃ and maintain the temperature for 2.5h. Cool the vacuum impregnation vessel to room temperature, wash five times with toluene at 65℃, and then filter. Transfer the filter cake to a drying oven at 75℃ and dry it to constant weight to obtain a non-halogen hydrogen bond acceptor complex material.

[0035] Example 3 This embodiment provides a method for preparing a non-halogen hydrogen bond acceptor complex material, which specifically includes the following steps: Step 1: Preparation of acid-activated porous silicon Mix 3 mol / L nitric acid and 10 wt% hydrogen peroxide at a volume ratio of 8:1 to obtain a nitric acid solution; Porous silica and nitric acid solution were added to a reaction flask at a solid-liquid ratio of 1:10 and stirred. The reaction flask was heated to 70°C and stirred for 5 hours. The reaction flask was then cooled to room temperature and filtered. The filter cake was washed with purified water until neutral and then dried. The filter cake was transferred to a drying oven at 80°C and dried to constant weight to obtain acid-activated porous silica.

[0036] Step 2: Preparation of unsaturated modified porous silicon Weigh out 100g of acid-activated porous silica, 11g of methacryloyloxypropyltrimethoxysilane, and 1000mL of anhydrous ethanol and add them to a reaction flask. Disperse the mixture by sonication for 50min. Fix the reaction flask on an iron stand with a mechanical stirrer. Heat the reaction flask to 60℃ and add 100mL of 2mol / L acetic acid solution. Keep the reaction at this temperature for 80min. Cool the reaction flask to room temperature and filter. Wash the filter cake with purified water until neutral and then dry it. Transfer the filter cake to a drying oven at 80℃ and dry it to constant weight to obtain unsaturated modified porous silica.

[0037] Step 3: Preparation of non-halogen hydrogen bond acceptor complex materials N-vinylpyrrolidone, N,N-dimethylacrylamide, ethylene glycol dimethacrylate, azobisisobutyronitrile and toluene were mixed and stirred until dissolved in a ratio of 80g:60g:8g:0.8g:400mL to obtain a polymerization solution; Weigh 500g of unsaturated modified porous silica and place it in a vacuum impregnation vessel. Evacuate the vessel to -0.095MPa and maintain the pressure for 30min to remove air from the pores. Then add 500mL of polymerization solution to the vacuum impregnation vessel and mix thoroughly. Heat the vacuum impregnation vessel to 90℃ and maintain the temperature for 3h. Cool the vacuum impregnation vessel to room temperature, wash it 5 times with toluene at 70℃, and then filter it. Transfer the filter cake to a drying oven at 80℃ and dry it to constant weight to obtain a non-halogen hydrogen bond acceptor complex material.

[0038] Example 4 This embodiment provides a method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent, specifically including the following steps: Step I: Preparation of pretreatment solution Boiling liquid containing propylene glycol methyl ether, propylene glycol methyl ether acetate, water, and organic impurities from the photoresist source is used as waste diluent generated from photoresist dilution, edge washing, substrate back cleaning, coating equipment cleaning, or pipeline replacement processes. Waste diluent, by mass percentage, includes: 1-80% propylene glycol methyl ether, 10-98% propylene glycol methyl ether acetate, 0.01-15% water, 0.001-20% organic impurities from photoresist sources, and 0-40% other organic solvents; Waste diluent and diatomaceous earth were mixed at a liquid-to-solid ratio of 10:1, stirred at room temperature for 20 minutes, filtered, and heavy components with boiling points higher than propylene glycol methyl ether acetate were removed to obtain a pretreated solution.

[0039] Step II: Separate and collect the propylene glycol methyl ether acetate enrichment solution. The pretreatment solution was fed into an immobilized complexation bed containing the non-halogenated hydrogen bond acceptor complexing material prepared in Example 1. The space velocity of the pretreatment solution entering the immobilized complexation bed was set to 1 h⁻¹. -1The operating pressure of the immobilized complexation separation bed was set to 0.3 MPa and the temperature to 35 °C, so that propylene glycol methyl ether and water could complex with the non-halogen hydrogen bond acceptor complexing material and be retained, so that propylene glycol methyl ether acetate would preferentially flow out relative to propylene glycol methyl ether, and the propylene glycol methyl ether acetate enriched solution was collected.

[0040] Step III: Separate and collect the replacement washing solution When the mass ratio of propylene glycol methyl ether to propylene glycol methyl ether acetate in the outlet liquid of the immobilized complexing separation bed reaches 20% of the mass ratio of propylene glycol methyl ether to propylene glycol methyl ether acetate in the inlet liquid of the immobilized complexing separation bed, the pretreatment liquid is stopped, and a portion of the propylene glycol methyl ether acetate enriched liquid is used as a replacement washing liquid and introduced into the immobilized complexing separation bed to replace the uncomplexed propylene glycol methyl ether acetate entrained in the immobilized complexing separation bed. The replacement washing liquid is then collected.

[0041] Step IV: Three-stage decompression pyrolysis complexation First stage of decomposition: The temperature of the immobilized complex separation bed was increased to 70℃, the operating pressure was set to 25kPa, the nitrogen purging rate was 80NL / (kg packing material·h), and the purging time was 2h. Propylene glycol methyl ether acetate enriched solution was collected. Second stage of decomplexation: The temperature of the immobilized complex separation bed was raised to 100℃, the operating pressure was set to 1kPa, the nitrogen purging rate was 80NL / (kg packing material·h), and the purging time was 3h. The desorbed liquid containing propylene glycol methyl ether was collected. Third Cooling Reuse Stage The temperature of the immobilized complex separation bed was reduced to 30℃, the operating pressure was set to atmospheric pressure, the nitrogen purging rate was 80NL / (kg packing·h), and the purging time was 3h. The immobilized bed was then switched back to the complex separation state.

[0042] Step V: Refining and preparing recovered propylene glycol methyl ether acetate The propylene glycol methyl ether acetate enrichment solution collected from the immobilized complex separation bed was combined with the displacement washing effluent, filtered through a 1 μm filter, and then fed into a light component removal and dehydration tower with 35 theoretical plates. The feed position was the 20th theoretical plate from the top of the tower. The operating pressure was set at 40 kPa, the top temperature at 80 °C, the bottom temperature at 100 °C, and the reflux ratio at 3. The light component containing propylene glycol methyl ether, water, and low-boiling substances was collected from the top of the tower, and crude propylene glycol methyl ether acetate was obtained from the bottom of the tower. Crude propylene glycol methyl ether acetate enters a propylene glycol methyl ether acetate product column with 60 theoretical plates. The feed position is at the 50th theoretical plate from the top of the column. The operating pressure is set at 20 kPa, the top temperature is 80℃, the bottom temperature is 115℃, and the reflux ratio is 5. Propylene glycol methyl ether acetate product is collected from the side stream near the 40th theoretical plate from the top of the column, and high-boiling residual liquid is discharged from the bottom of the column.

[0043] Step VI: Refining and preparing recovered propylene glycol methyl ether The propylene glycol methyl ether desorbate obtained in the second decomplexing stage was fed into a propylene glycol methyl ether dehydration and light ether removal column with 40 theoretical plates. The feed position was the 20th theoretical plate from the top of the column. The operating pressure was set to 60 kPa, the top temperature to 80℃, the bottom temperature to 100℃, and the reflux ratio to 3. The water-containing pre-distillate was collected from the top of the column, and the crude low-water propylene glycol methyl ether was obtained from the bottom of the column. Crude low-water propylene glycol methyl ether is fed into a propylene glycol methyl ether product column with 70 theoretical plates. The feed position is at the 20th theoretical plate from the top of the column. The operating pressure is set at 40 kPa, the top temperature at 95°C, the bottom temperature at 120°C, and the reflux ratio at 5. The product is collected from the top of the column. The fore-fraction is first cut off from the top of the column. After the water content of the current fraction is lower than 500 ppm, the propylene glycol methyl ether product fraction is collected. The propylene glycol methyl ether acetate enriched solution obtained from the bottom of the column is returned to the propylene glycol methyl ether acetate product column for purification treatment.

[0044] Example 5 This embodiment provides a method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent, specifically including the following steps: Step I: Preparation of pretreatment solution Boiling liquid containing propylene glycol methyl ether, propylene glycol methyl ether acetate, water, and organic impurities from the photoresist source is used as waste diluent generated from photoresist dilution, edge washing, substrate back cleaning, coating equipment cleaning, or pipeline replacement processes. Waste diluent, by mass percentage, includes: 1-80% propylene glycol methyl ether, 10-98% propylene glycol methyl ether acetate, 0.01-15% water, 0.001-20% organic impurities from photoresist sources, and 0-40% other organic solvents; Waste diluent and diatomaceous earth were mixed at a liquid-to-solid ratio of 10:1, stirred at room temperature for 25 minutes, filtered, and heavy components with boiling points higher than propylene glycol methyl ether acetate were removed to obtain a pretreated solution.

[0045] Step II: Separate and collect the propylene glycol methyl ether acetate enrichment solution. The pretreatment solution was fed into an immobilized complexation bed containing the non-halogenated hydrogen bond acceptor complexing material prepared in Example 2. The space velocity of the pretreatment solution entering the immobilized complexation bed was set to 1.5 h⁻¹. -1 The operating pressure of the immobilized complexation separation bed was set to 0.4 MPa and the temperature to 40 °C, so that propylene glycol methyl ether and water could complex with the non-halogen hydrogen bond acceptor complexing material and be retained, so that propylene glycol methyl ether acetate would preferentially flow out relative to propylene glycol methyl ether, and the propylene glycol methyl ether acetate enriched solution was collected.

[0046] Step III: Separate and collect the replacement washing solution When the mass ratio of propylene glycol methyl ether to propylene glycol methyl ether acetate in the outlet liquid of the immobilized complexing separation bed reaches 25% of the mass ratio of propylene glycol methyl ether to propylene glycol methyl ether acetate in the inlet liquid of the immobilized complexing separation bed, the pretreatment liquid is stopped, and a portion of the propylene glycol methyl ether acetate enriched liquid is used as a replacement washing liquid and introduced into the immobilized complexing separation bed to replace the uncomplexed propylene glycol methyl ether acetate entrained in the immobilized complexing separation bed. The replacement washing liquid is then collected.

[0047] Step IV: Three-stage decompression pyrolysis complexation First stage of decomposition: The temperature of the immobilized complex separation bed was increased to 75℃, the operating pressure was set to 27kPa, the nitrogen purging rate was 90NL / (kg packing material·h), and the purging time was 2.5h. Propylene glycol methyl ether acetate enriched solution was collected. Second stage of decomplexation: The temperature of the immobilized complex separation bed was increased to 110℃, the operating pressure was set to 5kPa, the nitrogen purging rate was 90NL / (kg packing material·h), and the purging time was 4h. The desorbed liquid containing propylene glycol methyl ether was collected. Third Cooling Reuse Stage The temperature of the immobilized complexation separation bed was reduced to 38℃, the operating pressure was set to atmospheric pressure, the nitrogen purging rate was 90NL / (kg packing material·h), and the purging time was 4h. The immobilized bed was then switched back to the complexation separation state.

[0048] Step V: Refining and preparing recovered propylene glycol methyl ether acetate The propylene glycol methyl ether acetate enrichment solution collected from the immobilized complex separation bed was combined with the displacement washing effluent, filtered through a 1μm filter, and then fed into a light component removal and dehydration tower with 45 theoretical plates. The feed position was the 20th theoretical plate from the top of the tower. The operating pressure was set at 50 kPa, the top temperature at 85℃, the bottom temperature at 110℃, and the reflux ratio at 4. The light component containing propylene glycol methyl ether, water, and low-boiling substances was collected from the top of the tower, and crude propylene glycol methyl ether acetate was obtained from the bottom of the tower. Crude propylene glycol methyl ether acetate enters a propylene glycol methyl ether acetate product column with 65 theoretical plates. The feed position is at the 50th theoretical plate from the top of the column. The operating pressure is set at 30 kPa, the top temperature is 90℃, the bottom temperature is 125℃, and the reflux ratio is 6. Propylene glycol methyl ether acetate product is collected from the side stream near the 40th theoretical plate from the top of the column, and high-boiling residual liquid is discharged from the bottom of the column.

[0049] Step VI: Refining and preparing recovered propylene glycol methyl ether The propylene glycol methyl ether desorbate obtained in the second decomplexing stage was fed into a propylene glycol methyl ether dehydration and light ether removal column with 45 theoretical plates. The feed position was the 20th theoretical plate from the top of the column. The operating pressure was set to 70 kPa, the top temperature to 85℃, the bottom temperature to 105℃, and the reflux ratio to 4. The water-containing pre-distillate was collected from the top of the column, and the crude low-water propylene glycol methyl ether was obtained from the bottom of the column. Crude low-water propylene glycol methyl ether is fed into a propylene glycol methyl ether product column with 75 theoretical plates. The feed position is the 20th theoretical plate from the top of the column. The operating pressure is set at 50 kPa, the top temperature at 100℃, the bottom temperature at 125℃, and the reflux ratio at 5.5. The product is collected from the top of the column. The fore-fraction is first removed from the top of the column. After the water content in the current fraction is lower than 500 ppm, the propylene glycol methyl ether product fraction is collected. The propylene glycol methyl ether acetate enriched solution obtained from the bottom of the column is returned to the propylene glycol methyl ether acetate product column for purification treatment.

[0050] Example 6 This embodiment provides a method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent, specifically including the following steps: Step I: Preparation of pretreatment solution Boiling liquid containing propylene glycol methyl ether, propylene glycol methyl ether acetate, water, and organic impurities from the photoresist source is used as waste diluent generated from photoresist dilution, edge washing, substrate back cleaning, coating equipment cleaning, or pipeline replacement processes. Waste diluent, by mass percentage, includes: 1-80% propylene glycol methyl ether, 10-98% propylene glycol methyl ether acetate, 0.01-15% water, 0.001-20% organic impurities from photoresist sources, and 0-40% other organic solvents; Waste diluent and diatomaceous earth were mixed at a liquid-to-solid ratio of 10:1, stirred at room temperature for 30 minutes, filtered, and heavy components with boiling points higher than propylene glycol methyl ether acetate were removed to obtain a pretreated solution.

[0051] Step II: Separate and collect the propylene glycol methyl ether acetate enrichment solution. The pretreatment solution was fed into an immobilized complexation bed containing the non-halogenated hydrogen bond acceptor complexing material prepared in Example 3. The space velocity of the pretreatment solution entering the immobilized complexation bed was set to 2 h⁻¹. -1 The operating pressure of the immobilized complexation separation bed was set to 0.5 MPa and the temperature to 45 °C, so that propylene glycol methyl ether and water could undergo complexation with the non-halogen hydrogen bond acceptor complexing material and be retained, so that propylene glycol methyl ether acetate would preferentially flow out relative to propylene glycol methyl ether, and the propylene glycol methyl ether acetate enriched solution was collected.

[0052] Step III: Separate and collect the replacement washing solution When the mass ratio of propylene glycol methyl ether to propylene glycol methyl ether acetate in the outlet liquid of the immobilized complexing separation bed reaches 30% of the mass ratio of propylene glycol methyl ether to propylene glycol methyl ether acetate in the inlet liquid of the immobilized complexing separation bed, the pretreatment liquid is stopped, and a portion of the propylene glycol methyl ether acetate enriched liquid is used as a replacement washing liquid and introduced into the immobilized complexing separation bed to replace the uncomplexed propylene glycol methyl ether acetate entrained in the immobilized complexing separation bed. The replacement washing liquid is then collected.

[0053] Step IV: Three-stage decompression pyrolysis complexation First stage of decomposition: The temperature of the immobilized complex separation bed was raised to 80℃, the operating pressure was set to 30kPa, the nitrogen purging rate was 100NL / (kg packing·h), and the purging time was 3h. Propylene glycol methyl ether acetate enriched solution was collected. Second stage of decomplexation: The temperature of the immobilized complex separation bed was increased to 120℃, the operating pressure was set to 10kPa, the nitrogen purging rate was 100NL / (kg packing material·h), and the purging time was 5h. The desorbed liquid containing propylene glycol methyl ether was collected. Third Cooling Reuse Stage The temperature of the immobilized complexation separation bed was reduced to 45℃, the operating pressure was set to atmospheric pressure, the nitrogen purging rate was 100NL / (kg packing·h), the purging time was 5h, and the fixed bed was switched back to the complexation separation state.

[0054] Step V: Refining and preparing recovered propylene glycol methyl ether acetate The propylene glycol methyl ether acetate enrichment solution collected from the immobilized complex separation bed was combined with the displacement washing effluent, filtered through a 1 μm filter, and then fed into a light component removal and dehydration tower with 50 theoretical plates. The feed position was the 20th theoretical plate from the top of the tower. The operating pressure was set at 60 kPa, the top temperature at 90 °C, the bottom temperature at 120 °C, and the reflux ratio at 5. The light component containing propylene glycol methyl ether, water, and low-boiling-point substances was collected from the top of the tower, and crude propylene glycol methyl ether acetate was obtained from the bottom of the tower. Crude propylene glycol methyl ether acetate enters a propylene glycol methyl ether acetate product column with 70 theoretical plates. The feed position is at the 50th theoretical plate from the top of the column. The operating pressure is set at 40 kPa, the top temperature is 100℃, the bottom temperature is 135℃, and the reflux ratio is 7. The propylene glycol methyl ether acetate product is collected from the side stream near the 40th theoretical plate from the top of the column, and the high-boiling residual liquid is discharged from the bottom of the column.

[0055] Step VI: Refining and preparing recovered propylene glycol methyl ether The propylene glycol methyl ether desorbate obtained in the second decomplexing stage was fed into a propylene glycol methyl ether dehydration and light ether removal column with 50 theoretical plates. The feed position was the 20th theoretical plate from the top of the column. The operating pressure was set to 80 kPa, the top temperature to 90℃, the bottom temperature to 110℃, and the reflux ratio to 5. The water-containing pre-distillate was collected from the top of the column, and the crude low-water propylene glycol methyl ether was obtained from the bottom of the column. Crude low-water propylene glycol methyl ether is fed into a propylene glycol methyl ether product column with 80 theoretical plates. The feed position is at the 20th theoretical plate from the top of the column. The operating pressure is set at 60 kPa, the top temperature at 105℃, the bottom temperature at 130℃, and the reflux ratio at 6. The product is collected from the top of the column. The fore-fraction is first cut off from the top of the column. After the water content of the current fraction is lower than 500 ppm, the propylene glycol methyl ether product fraction is collected. The propylene glycol methyl ether acetate enriched solution obtained from the bottom of the column is returned to the propylene glycol methyl ether acetate product column for purification treatment.

[0056] Comparative Example 1 The difference between this comparative example and Example 6 is that N-vinylpyrrolidone was not added to the polymerization solution in step 3 during the preparation of the non-halogenated hydrogen bond acceptor complex material.

[0057] Comparative Example 2 The difference between this comparative example and Example 6 is that N,N-dimethylacrylamide was not added to the polymerization solution in step 3 during the preparation of the non-halogen hydrogen bond acceptor complex material.

[0058] Comparative Example 3 The difference between this comparative example and Example 6 is that, in the three-stage decompression pyrolysis complexation process of step IV, the operating pressure is set to 10 kPa in the first decomposition stage.

[0059] Performance testing: The mass fractions of recovered propylene glycol methyl ether (PM) and propylene glycol methyl ether acetate (PGMEA) in Examples 4-6 and Comparative Examples 1-3 were determined in accordance with the standards HG / T 3939-2007 "Industrial Propylene Glycol Methyl Ether" and HG / T 3940-2007 "Industrial Propylene Glycol Methyl Ether Acetate". Reference formula The methods for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluents provided in Examples 4-6 and Comparative Examples 1-3 were used to determine the recovery rates of propylene glycol methyl ether and propylene glycol methyl ether acetate from the waste diluents at 1 h and 100 h of operation. The formula is as follows: m1 is the weight of the recovered propylene glycol methyl ether or propylene glycol methyl ether acetate, w1 is the mass fraction of the recovered propylene glycol methyl ether or propylene glycol methyl ether acetate, m0 is the weight of the waste diluent, and w... x The content of propylene glycol methyl ether or propylene glycol methyl ether acetate in the waste diluent is shown in Table 1 below.

[0060] Table 1 - Performance Test Data of Samples Data Analysis: This invention recovers propylene glycol methyl ether (PM) from waste diluent at a mass fraction of 99.78-99.81%, and recovers propylene glycol methyl ether acetate at a mass fraction of 99.53-99.85%. After 1 hour of operation, the recovery rate of PM from the waste diluent reaches 96.7-97.1%, and the recovery rate of propylene glycol methyl ether acetate (PGMEA) reaches 97.1-97.6%. After 100 hours of operation, the recovery rate of PM from the waste diluent reaches 94.1-94.7%, and the recovery rate of PGMEA reaches 99.53-99.85%. The yield reached 96.4-96.7%, and all performance test data were superior to the comparative example. This indicates that the present invention, through acid activation, silane modification, and in-situ polymerization within the pores, constructs a non-halogen hydrogen bond acceptor complex material. Stable hydrogen bond acceptor sites are formed within the porous silica channels, which form reversible hydrogen bond interactions with propylene glycol methyl ether and water, allowing propylene glycol methyl ether acetate to flow out preferentially. By utilizing the differences in the binding strength of different components, segmented release and material regeneration are achieved through three-stage depressurized pyrolysis complexation. This can maintain a high recovery rate and long-term operational stability while ensuring high-purity recovery of propylene glycol methyl ether or propylene glycol methyl ether acetate.

[0061] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent, characterized in that, Includes the following steps: S1. Pre-treat the waste diluent to remove solid particles, colloidal resins, and heavy components with boiling points higher than propylene glycol methyl ether acetate, to obtain a pre-treated solution. S2. The pretreatment solution enters the immobilized complexation separation bed filled with non-halogen hydrogen bond acceptor complexing material, so that propylene glycol methyl ether and water undergo complexation with the non-halogen hydrogen bond acceptor complexing material and are retained, so that propylene glycol methyl ether acetate flows out preferentially relative to propylene glycol methyl ether, and propylene glycol methyl ether acetate enriched solution is collected. S3. When the mass ratio of propylene glycol methyl ether to propylene glycol methyl ether acetate in the outlet liquid of the immobilized complexing separation bed reaches 20-30% of the mass ratio of propylene glycol methyl ether to propylene glycol methyl ether acetate in the inlet liquid of the immobilized complexing separation bed, stop the flow of pretreatment liquid, and use part of the propylene glycol methyl ether acetate enrichment liquid as replacement washing liquid to pass through the immobilized complexing separation bed to replace the uncomplexed propylene glycol methyl ether acetate entrained in the immobilized complexing separation bed, and collect the replacement washing liquid. S4. The immobilized complex separation bed after replacement washing is subjected to three stages of decomposition and pyrolysis in a first decomposition stage, a second decomposition stage, and a third cooling and reuse stage. In the first decomposition stage, propylene glycol methyl ether acetate enriched solution is collected. In the second decomposition stage, propylene glycol methyl ether desorbate is collected. In the third cooling and reuse stage, the fixed bed is switched back to the complex separation state. S5. The propylene glycol methyl ether acetate enrichment solution and the displacement washing solution are subjected to a first purification treatment to obtain the propylene glycol methyl ether acetate product. S6. The propylene glycol methyl ether desorption solution is subjected to a second purification treatment to obtain the propylene glycol methyl ether product.

2. The method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent according to claim 1, characterized in that, The waste diluent originates from photoresist dilution, edge washing, substrate back cleaning, coating equipment cleaning, or pipeline replacement processes, and contains propylene glycol methyl ether, propylene glycol methyl ether acetate, water, and organic impurities from photoresist sources. The waste diluent comprises, by mass percentage: 1-80% propylene glycol methyl ether, 10-98% propylene glycol methyl ether acetate, 0.01-15% water, 0.001-20% organic impurities from photoresist sources, and 0-40% other organic solvents.

3. The method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent according to claim 1, characterized in that, The pretreatment operation includes: mixing waste diluent and diatomaceous earth at a liquid-to-solid ratio of 10:1, stirring at room temperature for 20-30 minutes, filtering, and obtaining a pretreated solution.

4. The method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent according to claim 1, characterized in that, Non-halogen hydrogen bond acceptor complex materials are obtained by the following steps: A1. Mix N-vinylpyrrolidone, N,N-dimethylacrylamide, ethylene glycol dimethacrylate, azobisisobutyronitrile and toluene and stir until the system is dissolved to obtain a polymerization solution; A2. Place the unsaturated modified porous silicon in a vacuum impregnation vessel, evacuate to -0.08 to -0.095 MPa, and maintain for 10-30 minutes to remove air from the pores. Then, add the polymerization liquid to the vacuum impregnation vessel, stir, heat the reaction system to 80-90℃, and maintain the temperature for 2-3 hours. After post-treatment, a non-halogenated hydrogen bond acceptor complex material is obtained, wherein the unsaturated modified porous silicon is porous silicon modified with olefin siloxane.

5. The method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent according to claim 4, characterized in that, In step A1, the ratio of N-vinylpyrrolidone, N,N-dimethylacrylamide, ethylene glycol dimethacrylate, azobisisobutyronitrile, and toluene is 70-80g:50-60g:7-8g:0.6-0.8g:400mL; in step A2, the ratio of unsaturated modified porous silica to polymerization liquid is 10g:8-10mL.

6. The method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent according to claim 1, characterized in that, In step S3, the feed temperature of the immobilized complex separation bed is 35-45℃, the space velocity of the pretreatment solution entering the immobilized complex separation bed is 1-2h-1, and the operating pressure is 0.3-0.5MPa.

7. The method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent according to claim 1, characterized in that, In step S4, the temperature of the first decomplexing stage is 70-80℃, the operating pressure is 25-30kPa, the nitrogen purging rate is 80-100NL / (kg packing·h), and the purging time is 2-3h; the temperature of the second decomplexing stage is 100-120℃, the operating pressure is 1-10kPa, the nitrogen purging rate is 80-100NL / (kg packing·h), and the purging time is 3-5h; the temperature of the third cooling and reuse stage is 30-45℃, the operating pressure is atmospheric pressure, the nitrogen purging rate is 80-100NL / (kg packing·h), and the purging time is 3-5h.

8. The method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent according to claim 1, characterized in that, The first refining process includes: combining the propylene glycol methyl ether acetate enriched solution collected from the immobilized complex separation bed with the displacement washing effluent, filtering it through a 1μm filter, and sending it to a light component removal and dehydration tower; collecting the light component containing propylene glycol methyl ether, water, and low-boiling substances from the top of the tower, obtaining crude propylene glycol methyl ether acetate from the bottom of the tower, and sending the crude propylene glycol methyl ether acetate into the propylene glycol methyl ether acetate product tower, collecting the propylene glycol methyl ether acetate product from the side stream, and discharging the high-boiling residual liquid from the bottom of the tower.

9. The method for recovering propylene glycol methyl ether and propylene glycol methyl ether acetate from waste diluent according to claim 1, characterized in that, The second refining process includes: sending the propylene glycol methyl ether-containing desorbate obtained from the second decomplexing stage into a propylene glycol methyl ether dehydration and light removal column; collecting the water-containing pre-distillate from the top of the column; obtaining a low-water crude propylene glycol methyl ether from the bottom of the column; the low-water crude propylene glycol methyl ether entering the propylene glycol methyl ether product column; collecting the top of the column; first, cutting off the pre-distillate from the top of the column; collecting the propylene glycol methyl ether product distillate after the water content in the current distillate is below 500 ppm; and returning the propylene glycol methyl ether acetate enriched solution obtained from the bottom of the column to the propylene glycol methyl ether acetate refining process.

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