Method for recycling textiles

Abstract

According to the method for recycling the textiles, waste polyester-cotton mixed textiles and polyester or pure cotton textiles serve as raw materials, the upgrading and conversion process of the textiles is achieved through the catalytic conversion process, and the polyester-cotton mixed textiles and the polyester or pure cotton textiles can be converted into two high-value chemicals including terephthalic acid and / or ethylene glycol. The method is green and environment-friendly, the reaction steps are simple, the degradation rate of the textiles is high, the yield of high-value chemicals terephthalic acid and ethylene glycol is high, and efficient recovery of polyester cotton mixed textiles and polyester or pure cotton textiles is achieved.

Description

Technical Field

[0001] This application relates to the field of chemical recycling and degradation technology, and in particular to a method for recycling textiles. Background Technology

[0002] Polyester (polyethylene terephthalate, PET) fiber is widely used in apparel and home textiles due to its good stability, adaptability, and excellent physicochemical properties. As the largest product in the chemical fiber industry, PET fiber has a huge annual output. Polyester-cotton blended textiles, which combine the advantages of both polyester and cotton fibers, account for the largest proportion of PET fiber textiles. Due to the large consumption of polyester-cotton blended textiles, the amount recycled and reused is still relatively small. The vast majority is incinerated or landfilled after use, causing serious environmental pollution, consuming large amounts of land resources, causing secondary soil pollution, and hindering sustainable environmental development.

[0003] Currently, there are research reports on the recovery of polyester-cotton blended textiles using alcoholysis and acid hydrolysis. However, this method can only recover the relevant monomers of PET in polyester-cotton blended textiles. The cotton portion degrades into glucose and oligosaccharides, etc., and is not converted into high-value chemicals, which is not conducive to effective recycling and reuse. Therefore, the efficient recycling of polyester-cotton blended textiles, polyester, or pure cotton textiles to achieve high-value transformation of textiles remains a significant challenge. Summary of the Invention

[0004] The purpose of this application is to provide a method for recycling textiles, enabling the degradation and recycling of polyester-cotton blends, polyester, or pure cotton textiles into high-value chemicals. The specific technical solution is as follows:

[0005] A first aspect of this application provides a method for recycling textiles selected from polyester-cotton blends, the method comprising the following steps:

[0006] (1) In an inert atmosphere, the textile is subjected to a degradation reaction by heating with water as the reaction solvent and hydrolysis reagent under the action of the first catalyst terephthalic acid to generate terephthalic acid, ethylene glycol and cellulose (i.e., cellulose). The temperature of the degradation reaction is 180°C to 240°C and the time of the degradation reaction is 4h to 8h.

[0007] (2) Separate the pure cotton textiles. In a hydrogen atmosphere, the pure cotton textiles are heated to 200°C to 240°C for 4 to 8 hours with water as the reaction solvent and hydrolysis reagent under the action of the second catalyst to obtain ethylene glycol and by-products. The second catalyst is a nickel and tungsten carbide catalyst supported on activated carbon.

[0008] The second aspect of this application provides a method for recycling textiles selected from polyester. The method includes the following steps: in an inert atmosphere, the textiles undergo a degradation reaction under the action of a first catalyst, terephthalic acid, with water as the reaction solvent and hydrolysis reagent, and are heated to generate terephthalic acid and ethylene glycol. The temperature of the degradation reaction is 180°C to 240°C, and the time of the degradation reaction is 4 hours to 8 hours.

[0009] A third aspect of this application provides a method for recycling textiles, the textiles being selected from pure cotton textiles, the method comprising the following steps: in a hydrogen atmosphere, the textiles, under the action of a second catalyst, react with water as a reaction solvent and hydrolysis reagent, heated to 200°C to 240°C for 4 to 8 hours to obtain ethylene glycol and byproducts; the second catalyst is activated carbon supported on nickel and tungsten carbide.

[0010] In some embodiments of this application, the mass ratio of the textile to the first catalyst is 1:1 to 4:1.

[0011] In some embodiments of this application, the mass ratio of polyester to pure cotton textile in the polyester-cotton blended textile is 25:75 to 75:25.

[0012] In some embodiments of this application, the degradation reaction is carried out at a temperature of 200°C to 240°C.

[0013] In some embodiments of this application, the mass ratio of water to the polyester-cotton blend or the polyester is from 10:1 to 100:1.

[0014] In some embodiments of this application, the mass ratio of water to the pure cotton textile is from 10:1 to 160:1.

[0015] In some embodiments of this application, the mass ratio of the pure cotton textile to the second catalyst is 2:1 to 10:1.

[0016] In some embodiments of this application, the nickel content is 0.5% to 5% by mass, and the tungsten carbide content is 10% to 50% by mass, based on the mass of the second catalyst.

[0017] In some embodiments of this application, the byproduct is selected from at least one of 1,2-propanediol, glycerol, 1,2-butanediol, erythrose, sorbitol, or mannitol, and the yield of the byproduct is from 4% to 17%.

[0018] In some embodiments of this application, the pressure of the hydrogen atmosphere is 4 MPa to 8 MPa.

[0019] The beneficial effects of this application are:

[0020] This application provides a method for recycling textiles. Using waste polyester-cotton blended textiles, polyester, or pure cotton textiles as raw materials, a catalytic conversion process is employed to upgrade and transform these textiles into two high-value chemicals: terephthalic acid and / or ethylene glycol. This method is environmentally friendly, has simple reaction steps, achieves a high degradation rate of textiles, and yields high amounts of the high-value chemicals terephthalic acid and ethylene glycol, thus realizing the efficient recycling of polyester-cotton blended textiles, polyester, or pure cotton textiles.

[0021] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.

[0023] Figure 1 The 1H NMR spectrum of terephthalic acid isolated from the product of step (1) in Example 1;

[0024] Figure 2 The 1H NMR spectrum of ethylene glycol separated from the product of step (2) in Example 1. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0026] To recycle waste polyester-cotton blended textiles, existing technologies describe the degradation and recycling of these textiles using water as a solvent and p-benzenesulfonic acid as a catalyst. In this method, the degradation product of the polyester portion is terephthalic acid, with a low polyester degradation rate and a terephthalic acid yield of less than 5%. Although the cotton portion can achieve 100% degradation, its products are glucose and 5-hydroxymethylfurfural, which have low application value, and the yields of these two products are also too low, less than 20%. As an improvement, replacing the solvent with a mixed solvent composed of water and a polar aprotic solvent can improve the degradation rate of polyester and the yield of terephthalic acid, but the cotton portion will still degrade into microcrystalline cellulose, oligosaccharides, glucose, and 5-hydroxymethylfurfural, with a yield still low, not exceeding 50%. Therefore, efficient recycling and high-value conversion of polyester-cotton blended textiles have not yet been achieved.

[0027] In view of this, a first aspect of this application provides a method for recycling textiles selected from polyester-cotton blends, the method comprising the following steps:

[0028] (1) In an inert atmosphere, textiles undergo a degradation reaction under the action of the first catalyst terephthalic acid, with water as the reaction solvent and hydrolysis reagent, and are heated to produce terephthalic acid, ethylene glycol and pure cotton textiles (i.e. cellulose).

[0029] (2) Separate pure cotton textiles. Under a hydrogen atmosphere, the pure cotton textiles are reacted with water as a reaction solvent and hydrolysis reagent under the action of the second catalyst. The reaction is heated to 200°C to 240°C for 4 to 8 hours to obtain ethylene glycol and by-products. The second catalyst is a nickel and tungsten carbide catalyst (Ni-W2C / AC, where AC represents activated carbon) supported on activated carbon.

[0030] In step (1) above, the degradation reaction temperature is 180℃ to 240℃, and the degradation reaction time is 4h to 8h. Preferably, the degradation reaction temperature is 200℃ to 240℃. For example, the degradation reaction temperature can be 180℃, 195℃, 200℃, 210℃, 220℃, 235℃, 240℃, or any two of these values, and the degradation reaction time can be 4h, 5h, 6h, 7h, 8h, or any two of these values. When the degradation reaction temperature is too low or the time is too short, for example, the temperature is below 180℃ or the time is less than 4h, it is not conducive to the degradation reaction, the degradation rate of polyester-cotton blended textiles is low, and the yield of terephthalic acid and ethylene glycol is too low. When the degradation reaction temperature is too high or the time is too long, for example, the temperature is above 240℃ or the time is greater than 8h, the degradation rate of polyester-cotton blended textiles will decrease slightly and cannot be further improved. Moreover, excessively high temperature or excessively long reaction time will increase energy consumption, which is not in line with the concept of green environmental protection. In step (2) above, the reaction temperature is 200℃ to 240℃, and the reaction time is 4h to 8h. For example, the reaction temperature can be 200℃, 210℃, 220℃, 235℃, 240℃, or any two of these values, and the reaction time can be 4h, 5h, 6h, 7h, 8h, or any two of these values. When the reaction temperature is too low or the time is too short, for example, below 200℃ or less than 4h, it is not conducive to the reaction in step (2), resulting in a low degradation rate of pure cotton textiles and a low yield of ethylene glycol. When the reaction temperature is too high or the time is too long, for example, above 240℃ or more than 8h, the degradation rate of pure cotton textiles will decrease slightly and cannot be further improved. Moreover, excessively high temperatures or long reaction times will increase energy consumption, which is not in line with the concept of green environmental protection. Therefore, adjusting the reaction temperature and time within the above range is beneficial to the upgrading and transformation of polyester-cotton blended textiles.

[0031] The method for recycling textiles provided in the first aspect of this application uses waste polyester-cotton blended textiles as raw materials and achieves the upgrading and transformation of these textiles through a stepwise catalytic process, converting them into two high-value chemicals: terephthalic acid and ethylene glycol. The stepwise catalytic transformation process of polyester-cotton blended textiles is as follows:

[0032]

[0033] Among them, the polyester-cotton blended textiles are a mixture of polyester and pure cotton textiles (cellulose), the degree of polymerization of cellulose is 2m, and the by-products are selected from at least one of 1,2-propanediol, glycerol, 1,2-butanediol, erythrose, sorbitol or mannitol.

[0034] This method uses water as both the reaction solvent and the hydrolysis reagent, enabling efficient catalytic hydrolysis of polyester-cotton blended textiles. It is environmentally friendly, with simple reaction steps, high degradation rates of polyester-cotton blended textiles, high yields of the high-value chemicals terephthalic acid and ethylene glycol, and high selectivity for ethylene glycol, thus achieving efficient recycling of polyester-cotton blended textiles.

[0035] In this application, there are no particular limitations on the method for separating pure cotton textiles, as long as the purpose of this application can be achieved. In step (1) above, the terephthalic acid, ethylene glycol, and pure cotton textiles generated by the degradation reaction after heating can be separated into a solid mixture of terephthalic acid and pure cotton textiles by centrifugation after the reaction is completed. The clear liquid is an aqueous solution of ethylene glycol. Then, the solid mixture is washed with dichloromethane solution, and the dichloromethane solution of terephthalic acid and pure cotton textiles are separated by centrifugation. Finally, the aqueous solution of ethylene glycol, the dichloromethane solution of terephthalic acid, and the pure cotton textiles are dried by rotary evaporation to obtain terephthalic acid, ethylene glycol, and pure cotton textiles. Thus, the terephthalic acid, ethylene glycol, and pure cotton textiles generated by the degradation reaction can be separated.

[0036] In step (2) above, after the reaction is complete, a mixture of ethylene glycol and byproducts is obtained. The products after the reaction can be directly analyzed by gas chromatography and liquid chromatography. Alternatively, the mixture can be separated. This application does not impose any particular restrictions on the separation process; commonly used separation methods in the field can be used, as long as they achieve the purpose of this application. For example, separation can be performed by silica gel column chromatography.

[0037] The second aspect of this application provides a method for recycling textiles selected from polyester. The method includes the following steps: in an inert atmosphere, the textiles undergo a degradation reaction by heating with water as a reaction solvent and hydrolysis reagent, under the action of a first catalyst, terephthalic acid, to generate terephthalic acid and ethylene glycol.

[0038] In this method, the degradation reaction temperature is between 180℃ and 240℃, and the degradation reaction time is between 4h and 8h. Preferably, the degradation reaction temperature is between 200℃ and 240℃. For example, the degradation reaction temperature can be 180℃, 195℃, 200℃, 210℃, 220℃, 235℃, 240℃, or any range of two of these values, and the degradation reaction time can be 4h, 5h, 6h, 7h, 8h, or any range of two of these values.

[0039] The method for recycling textiles provided in the second aspect of this application uses waste polyester as raw material and achieves the upgrading and transformation of polyester through a one-step catalytic process, converting polyester into two high-value chemicals: terephthalic acid and ethylene glycol. The polyester catalytic transformation process is as follows:

[0040]

[0041] Where n is the degree of polymerization of polyester.

[0042] This method uses water as the reaction solvent, enabling efficient catalytic hydrolysis of polyester. It is environmentally friendly, with simple reaction steps, high polyester degradation rate, and high yields of the valuable chemicals terephthalic acid and ethylene glycol, achieving efficient polyester recovery.

[0043] In this application, there are no particular limitations on the separation method of the above-mentioned terephthalic acid and ethylene glycol, as long as it can achieve the purpose of this application. For example, after the catalytic reaction of the above-mentioned polyester is completed and cooled to room temperature, terephthalic acid can be precipitated from the reaction solution. The aqueous solutions of terephthalic acid and ethylene glycol can be separated by means of filtration, centrifugation, etc., and then the aqueous solution of ethylene glycol can be dried by rotary evaporation to obtain ethylene glycol.

[0044] The third aspect of this application provides a method for recycling textiles, the textiles being selected from pure cotton textiles. The method includes the following steps: in a hydrogen atmosphere, the textiles are reacted with water as a reaction solvent and hydrolysis reagent under the action of a second catalyst, heated to 200°C to 240°C for 4 to 8 hours to obtain ethylene glycol and byproducts. The second catalyst is a nickel and tungsten carbide catalyst supported on activated carbon.

[0045] In this method, the reaction temperature is between 200℃ and 240℃, and the reaction time is between 4h and 8h. For example, the reaction temperature can be 200℃, 210℃, 220℃, 235℃, 240℃, or any range of two of these values, and the reaction time can be 4h, 5h, 6h, 7h, 8h, or any range of two of these values.

[0046] The method for recycling textiles provided in the third aspect of this application uses waste pure cotton textiles as raw materials and achieves the upgrading and transformation of pure cotton textiles through a one-step catalytic process under the action of a second catalyst, converting pure cotton textiles into the high-value chemical ethylene glycol. The catalytic transformation process of pure cotton textiles is as follows:

[0047]

[0048] Pure cotton textiles are also known as cellulose, in which the degree of polymerization of cellulose is 2m, and the by-products are selected from at least one of 1,2-propanediol, glycerol, 1,2-butanediol, erythrose, sorbitol or mannitol.

[0049] This method uses water as a reaction solvent, enabling efficient catalytic hydrolysis of pure cotton textiles. It is environmentally friendly, has simple reaction steps, achieves a high degradation rate of pure cotton textiles, and exhibits high selectivity for the high-value chemical ethylene glycol, thus realizing the efficient recycling of pure cotton textiles.

[0050] After the above catalytic conversion process is completed, a mixture of ethylene glycol and byproducts is obtained. The products can be directly analyzed by gas chromatography and liquid chromatography. Alternatively, the mixture can be separated. This application does not impose any particular restrictions on the separation process, as long as it achieves the purpose of this application. For example, the method used in the method for recycling textiles provided in the first aspect of this application can be used for separation.

[0051] In this application, there is no particular limitation on the weight-average molecular weight of polyester, as long as the purpose of this application is achieved. For example, the weight-average molecular weight of polyester can be between 50,000 and 5,000,000. Similarly, in this application, there is no particular limitation on the weight-average molecular weight of pure cotton textiles, as long as the purpose of this application is achieved. For example, the weight-average molecular weight of pure cotton textiles can be between 50,000 and 5,000,000. In this application, the weight-average molecular weights of both polyester and pure cotton textiles in polyester-cotton blended textiles can be selected within the above ranges.

[0052] In this application, an inert atmosphere is used as a protective atmosphere during the reaction process. This application does not impose any particular limitation on the inert atmosphere; those skilled in the art can select one according to the actual situation, as long as the purpose of this application is achieved. For example, it can be at least one of nitrogen (N2), helium (He), or argon (Ar). This application does not impose any particular limitation on the gas pressure of the inert atmosphere, as long as the purpose of this application is achieved; for example, it can be from 1 MPa to 2 MPa.

[0053] In some embodiments of this application, the mass ratio of textiles to the first catalyst is from 1:1 to 4:1. For example, the mass ratio of textiles to the first catalyst can be 1:1, 2:1, 3:1, 4:1, or a range consisting of any two of these values. Adjusting the mass ratio of textiles to the first catalyst within the above range is beneficial for maximizing the effect of the first catalyst, resulting in a high degradation rate of textiles and a high yield of high-value chemicals, thereby better achieving the efficient recycling of polyester-cotton blended textiles or polyester.

[0054] In some embodiments of this application, the mass ratio (polyester-cotton mass ratio) of polyester to pure cotton textiles in polyester-cotton blended textiles is between 25:75 and 75:25. For example, the mass ratio of polyester to pure cotton textiles in polyester-cotton blended textiles can be 25:75, 30:70, 40:60, 50:50, 60:40, 75:25, or a range consisting of any two of these values. When the mass ratio of polyester to pure cotton textiles in polyester-cotton blended textiles is within the above range, the method provided in this application can better achieve the recycling of polyester-cotton blended textiles.

[0055] In some embodiments of this application, the mass ratio of water to the polyester-cotton blend or polyester fiber is from 10:1 to 100:1. For example, the mass ratio of water to the polyester-cotton blend or polyester fiber can be 10:1, 20:1, 40:1, 60:1, 80:1, 100:1, or a range of any two of these values. Controlling the mass ratio of water to the polyester-cotton blend or polyester fiber within the above range is beneficial for efficiently achieving the catalytic hydrolysis of both the polyester-cotton blend and the polyester fiber.

[0056] In some embodiments of this application, the mass ratio of water to pure cotton textiles is from 10:1 to 160:1. The mass ratio of water to pure cotton textiles can be 10:1, 20:1, 40:1, 60:1, 80:1, 100:1, 120:1, 140:1, 160:1, or a range of any two of these values. Regulating the mass ratio of water to pure cotton textiles within the above range is beneficial for efficiently achieving the catalytic hydrolysis of polyester-cotton blends and pure cotton textiles.

[0057] In some embodiments of this application, the mass ratio of pure cotton textiles to the second catalyst is from 2:1 to 10:1. For example, the mass ratio of pure cotton textiles to the second catalyst can be 2:1, 3:1, 4:1, 5:1, 6:1, 8:1, 10:1, or any range of two of these values. Regulating the mass ratio of pure cotton textiles to the second catalyst within the above range is beneficial for maximizing the effect of the second catalyst, resulting in a higher degradation rate of the textiles, a higher yield of high-value chemicals, and higher selectivity for ethylene glycol, thereby better achieving the recycling of polyester-cotton blended textiles or pure cotton textiles.

[0058] In some embodiments of this application, the mass percentage of nickel is 0.5% to 5%, and the mass percentage of tungsten carbide is 10% to 50%, based on the mass of the second catalyst. For example, the mass percentage of nickel can be 0.5%, 1.5%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.5%, 4%, 4.5%, 5%, or a range of any two of these values, and the mass percentage of tungsten carbide can be 10%, 20%, 25%, 28%, 30%, 35%, 40%, 50%, or a range of any two of these values. The second catalyst can be 0.5% Ni-10% W₂C / AC, 2% Ni-10% W₂C / AC, 2% Ni-30% W₂C / AC, 2% Ni-50% W₂C / AC, or 5% Ni-50% W₂C / AC, preferably 2% Ni-30% W₂C / AC. For example, when the second catalyst is 2% Ni-30% W2C / AC, in this composition, based on the mass of the second catalyst, the mass percentage of nickel is 2%, the mass percentage of tungsten carbide is 30%, and the balance is activated carbon. The composition of the second catalyst within the above range can result in a high degradation rate of textiles, a high yield of high-value chemicals, and high selectivity for ethylene glycol, thereby better enabling the recycling of polyester-cotton blended textiles or pure cotton textiles.

[0059] This application does not impose any particular limitation on the preparation method of the second catalyst, as long as it achieves the purpose of this application. For example, it can be prepared by impregnating activated carbon with a solution containing Ni(NO3)2 hydrate and NH4)6H2W. 12 O 40 The solid powder obtained by drying in an aqueous solution at 200°C to 250°C for 8 to 15 hours, followed by reduction activation in a pure hydrogen atmosphere, yields the second catalyst described above. The second catalyst needs to be transferred under the protection of an inert gas, avoiding contact with air during the transfer process. This application relates to the activated carbon, Ni(NO3)2 hydrate, and NH4)6H2W... 12 O 40 There are no particular limitations on the mass ratio; those skilled in the art can design it based on the composition of the second catalyst, as long as it achieves the purpose of this application. The inert gas used to protect the second catalyst can be at least one of nitrogen (N2), helium (He), or argon (Ar).

[0060] In some embodiments of this application, the byproducts are selected from at least one of 1,2-propanediol, glycerol, 1,2-butanediol, erythrose, sorbitol, or mannitol, and the yield of the byproducts is from 4% to 17%. For example, the yield of the byproducts can be 4%, 5%, 6%, 8%, 9%, 10%, 11%, 12%, 15%, 17%, or a range of any two of these values. In this application, each substance in the byproducts is only qualitatively analyzed, and the total amount of the above-mentioned byproducts is quantitatively analyzed. The yield of the byproducts refers to the total yield of the above-mentioned substances. The above-mentioned byproducts are easily separated from the high-value chemical ethylene glycol. The low yield of the above-mentioned byproducts indicates a high yield of the high-value chemical ethylene glycol and high selectivity for ethylene glycol, thereby better realizing the recycling of polyester-cotton blended textiles or pure cotton textiles.

[0061] In some embodiments of this application, the pressure of the hydrogen atmosphere is between 4 MPa and 8 MPa, for example, the pressure of the hydrogen atmosphere can be 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, or a range of any two of these values. Adjusting the pressure of the hydrogen atmosphere within the above range is more conducive to the catalytic conversion of pure cotton textiles, thereby improving the yield and selectivity of the high-value chemical ethylene glycol.

[0062] In this application, there are no particular restrictions on the container in which the above reaction takes place, as long as it can achieve the purpose of this application. For example, a high-pressure reactor can be used for the reaction conversion.

[0063] Example

[0064] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0065] Test methods and equipment:

[0066] MRI test:

[0067] The product's 1H NMR spectrum was determined using a 400MHz Bruker Avance III nuclear magnetic resonance spectrometer to confirm its structural formula, and terephthalic acid and ethylene glycol were quantitatively analyzed. Dimethyl sulfoxide (DMSO) was used as the solvent for terephthalic acid analysis, and heavy water (D₂O) was used as the solvent for ethylene glycol analysis, with methanol as an internal standard.

[0068] Yield testing and calculation:

[0069] The products of each reaction step were analyzed using a gas chromatography system (Agilent 7820A) and a liquid chromatography system (Agilent 1200) to obtain the molar amounts of ethylene glycol (EG) and byproducts. The yields of each reaction product were calculated using the following formula:

[0070] The yield (%) of TPA in step (1) = (mass of TPA obtained after reaction in step (1) - mass of the first catalyst) / theoretical mass of TPA for polyester degradation in polyester-cotton blended textiles;

[0071] The yield (%) of EG in step (1) = the mass of EG obtained after the reaction in step (1) / the theoretical mass of EG from polyester degradation in the polyester-cotton blended textile;

[0072] The mass (mg) of pure cotton textiles (cellulose) obtained in step (1) = the mass of the remaining solids after the recovery of TPA and EG in step (1);

[0073] The yield (%) of EG in step (2) = the amount of EG in the liquid product × 3 / the molar amount of monomer in cellulose;

[0074] By-product yield (%) = molar amount of by-product / molar amount of monomer in cellulose.

[0075] A higher yield of ethylene glycol indicates a higher selectivity for ethylene glycol.

[0076] Example 1-1

[0077] Preparation of the second catalyst: 2g of activated carbon was impregnated in 3mL of a solution containing 0.315g of Ni(NO3)2 hydrate and 1.177g of (NH4)6H2W. 12 O 40 The solid powder obtained by heating the aqueous solution at 220°C for 12 hours was then reduced and activated in a pure hydrogen atmosphere to obtain the second catalyst 2%Ni-30%W2C / AC.

[0078] Step (1): Add 2g of polyester-cotton blended textile (polyester-cotton mass ratio of 50:50, where the weight average molecular weight of polyester is 50,000 and the weight average molecular weight of cotton is 5,000,000) to 20mL (i.e., 20g) of water, add 500mg of the first catalyst terephthalic acid, stir evenly, and then add to the reaction vessel. Fill the reaction vessel with N2 and pressurize it to 1MPa. Then heat to T1=200℃ and react for t1=4h to carry out the degradation reaction. After the reaction is completed, cool to room temperature to allow terephthalic acid to precipitate from the reaction solution. Then centrifuge to obtain a solid mixture of terephthalic acid and pure cotton textile and an aqueous solution of ethylene glycol. Then wash with dichloromethane, centrifuge the solid mixture to separate the solid pure cotton textile and the dichloromethane solution of terephthalic acid. Finally, dry the above aqueous solution of ethylene glycol at 80℃ by rotary evaporation to obtain ethylene glycol. Terephthalic acid is obtained by rotary evaporation and drying of a dichloromethane solution at 30°C. Cellulose is obtained by rotary evaporation and drying of pure cotton textiles at 80°C.

[0079] Step (2): Take 1g of the cellulose obtained in the above step and add it to 20mL of water. After stirring evenly, add it to the reaction vessel. Under nitrogen protection, add 200mg of the second catalyst 2%Ni-30%W2C / AC to the reaction vessel. Then, purge the reaction vessel with hydrogen gas at a pressure of 6MPa, and heat it to T2 = 220℃ for t2 = 4h. After the reaction is completed, separate the reaction products by silica gel column chromatography to separate ethylene glycol and by-products.

[0080] Examples 1-2 to 1-22

[0081] Except for adjusting the parameters according to Table 1, everything else is the same as in Example 1-1.

[0082] Examples 2-1 to 2-2

[0083] In addition to adjusting the Ni(NO3)2 hydrate and (NH4)6H2W in the preparation of the second catalyst 12 O 40 The quality of the second catalyst is such that, except for the composition shown in Table 2, it is the same as in Examples 1-1.

[0084] Example 3-1

[0085] 2g of polyester (weight-average molecular weight of polyester is 50,000) was added to 20mL of water, along with 500mg of the first catalyst, terephthalic acid. After stirring thoroughly, the mixture was added to a reaction vessel, which was then purged with N2 at a pressure of 1MPa. The reaction was then heated to T1 = 200℃ and the reaction proceeded for t1 = 4h. After the reaction was completed, the mixture was cooled to room temperature to allow the terephthalic acid to precipitate from the reaction solution. The terephthalic acid solid and an aqueous solution of ethylene glycol were then separated by centrifugation. Finally, the terephthalic acid solid was dried at 80℃, and the aqueous solution of ethylene glycol was dried by rotary evaporation at 80℃ to obtain ethylene glycol. The mass ratios of water to textiles, textiles to the first catalyst, and polyester to cotton were the same as in Examples 1-1.

[0086] Example 3-2

[0087] 1g of pure cotton textile (weight average molecular weight 50,000) was added to 20mL of water, stirred thoroughly, and then added to a reaction vessel. Under nitrogen protection, 200mg of the second catalyst (2% Ni-30% W₂C / AC) was added to the reaction vessel, and then hydrogen gas was introduced into the reaction vessel at a pressure of 6MPa. The reaction was then heated to T₂ = 220℃ and the reaction time was t₂ = 4h. After the reaction was completed, the product was separated by silica gel column chromatography to separate ethylene glycol and byproducts.

[0088] The preparation of the second catalyst was the same as in Example 1-1; the mass ratio of water to pure cotton textiles was 20:1, and the mass ratio of pure cotton textiles to the second catalyst was 5:1.

[0089] Comparative Examples 1 to 2

[0090] Except for adjusting the parameters according to Table 1, everything else is the same as in Example 1-1.

[0091] The reaction parameters and test results of each embodiment and comparative example are shown in Tables 1 to 3.

[0092] Table 1

[0093]

[0094] Note: In Table 1, " / " indicates that the corresponding parameter does not exist.

[0095] As can be seen from Examples 1-1 to 1-5, when the temperature T1 and time t1 of the degradation reaction are within the range of this application, not only can high-value conversion of polyester-cotton blended textiles be achieved, but also high yield can be obtained.

[0096] As can be seen from Examples 1-1, 1-6 to 1-9, when the mass ratio of water to textiles is within the range of this application, not only can high-value conversion of polyester-cotton blended textiles be achieved, but also a high yield can be obtained.

[0097] As can be seen from Examples 1-1, 1-10 to 1-12, when the reaction temperature T2 and time t1 in step (2) are within the range of this application, not only can the high-value conversion of polyester-cotton blended textiles be achieved, but the high-value chemicals have high yields of phthalic acid and ethylene glycol, and high selectivity for ethylene glycol.

[0098] As can be seen from Examples 1-1, 1-3 to 1-16, when the mass ratio of water to pure cotton textiles is within the scope of this application, not only can high-value conversion of polyester-cotton blended textiles be achieved, but also the high yield of high-value chemicals for phthalic acid and ethylene glycol, and the high selectivity for ethylene glycol.

[0099] As can be seen from Examples 1-1, 1-17 to 1-18, when the mass ratio of textiles to the first catalyst is within the range of this application, not only can high-value conversion of polyester-cotton blended textiles be achieved, but also high yield can be obtained.

[0100] As can be seen from Examples 1-1, 1-19 to 1-20, when the polyester-cotton mass ratio in the polyester-cotton blended textile is within the range of this application, not only can the high-value conversion of the polyester-cotton blended textile be achieved, but it also has a high yield.

[0101] As can be seen from Examples 1-1, 1-21 to 1-22, when the mass ratio of pure cotton textiles and the second catalyst is within the range of this application, not only can high-value conversion of polyester-cotton blended textiles be achieved, but also the high-value chemicals have high yields of phthalic acid and ethylene glycol, and high selectivity for ethylene glycol.

[0102] Figure 1 The 1H NMR spectrum of terephthalic acid obtained in step (1) of Example 1 is shown. Peak a at 8.0 ppm and peak b at 13.4 ppm are signals of terephthalic acid, and the peak at 2.5 ppm corresponds to the solvent DMSO.

[0103] Figure 2 The 1H NMR spectrum of ethylene glycol obtained in step (2) of Example 1 is shown. Peak c at a chemical shift of 3.6 ppm is the signal of ethylene glycol, and the peak at a chemical shift of 4.8 ppm corresponds to the solvent D2O.

[0104] Table 2

[0105] Second catalyst Yield (%) of EG in step (2) By-product yield (%) Example 1-1 <![CDATA[2%Ni-30%W2C / AC]]> 75 10 Example 2-1 <![CDATA[0.5%Ni-10%W2C / AC]]> 40 36 Example 2-2 <![CDATA[5%Ni-50%W2C / AC]]> 60 10

[0106] As can be seen from Examples 1-1, 2-1 to 2-2, when the mass percentage of nickel and tungsten carbide in the second catalyst is within the range of this application, not only can high-value conversion of polyester-cotton blended textiles be achieved, but also the high yield of high-value chemicals for phthalic acid and ethylene glycol, and the high selectivity for ethylene glycol.

[0107] Table 3

[0108] textile TPA yield (%) EG yield (%) By-product yield (%) Example 3-1 Polyester 98 99 / Example 3-2 pure cotton textiles / 76 10

[0109] Note: In Table 3, " / " indicates that the corresponding parameter does not exist.

[0110] As can be seen from Examples 3-1, the method provided in this application can not only achieve high-value conversion of polyester, but also has a high yield.

[0111] As can be seen from Examples 3-2, the method provided in this application can not only achieve high-value conversion of pure cotton textiles, but also achieve a high yield of the high-value chemical ethylene glycol, with high selectivity for ethylene glycol and a low yield of by-products.

[0112] In summary, the textile recycling method provided in this application enables the upgrading and transformation of waste polyester-cotton blended textiles, polyester, or pure cotton textiles through a catalytic conversion process. This process converts these textiles into two high-value chemicals: terephthalic acid and / or ethylene glycol. This method is environmentally friendly, has simple reaction steps, achieves a high degradation rate of textiles, and yields high amounts of the high-value chemicals terephthalic acid and ethylene glycol, thus enabling efficient recycling of polyester-cotton blended textiles, polyester, or pure cotton textiles.

[0113] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, or article that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, or article.

[0114] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0115] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for recycling textiles, wherein, The textile is selected from polyester-cotton blend textiles, and the method includes the following steps: (1) In an inert atmosphere, the textile is subjected to a degradation reaction by heating with water as the reaction solvent and hydrolysis reagent under the action of the first catalyst terephthalic acid to generate terephthalic acid, ethylene glycol and pure cotton textile. The temperature of the degradation reaction is 180°C to 240°C and the time of the degradation reaction is 4h to 8h. (2) Separate the pure cotton textiles. In a hydrogen atmosphere, the pure cotton textiles are heated to 200°C to 240°C for 4 to 8 hours with water as the reaction solvent and hydrolysis reagent under the action of the second catalyst to obtain ethylene glycol and by-products. The second catalyst is a nickel and tungsten carbide catalyst supported on activated carbon.

2. A method for recycling textiles, wherein, The textile is selected from polyester, and the method includes the following steps: In an inert atmosphere, the textile is subjected to a degradation reaction in the presence of a first catalyst, terephthalic acid, with water as the reaction solvent and hydrolysis reagent, and heated to produce terephthalic acid and ethylene glycol. The degradation reaction is carried out at a temperature of 180°C to 240°C for a duration of 4 to 8 hours.

3. A method for recycling textiles, wherein, The textile is selected from pure cotton textiles, and the method includes the following steps: In a hydrogen atmosphere, the textile is reacted with water as a reaction solvent and hydrolysis reagent under the action of a second catalyst, heated to 200°C to 240°C for 4 to 8 hours to obtain ethylene glycol and byproducts; the second catalyst is a nickel and tungsten carbide catalyst supported on activated carbon.

4. The method according to claim 1 or 2, wherein, The mass ratio of the textile to the first catalyst is from 1:1 to 4:

1.

5. The method according to claim 1, wherein, The mass ratio of polyester to pure cotton textiles in the polyester-cotton blended textile is 25:75 to 75:

25.

6. The method according to claim 1 or 2, wherein, The degradation reaction is carried out at a temperature of 200°C to 240°C.

7. The method according to claim 1 or 2, wherein, The mass ratio of water to the polyester-cotton blend or the polyester is from 10:1 to 100:

1.

8. The method according to claim 1 or 3, wherein, The mass ratio of water to the pure cotton textile is from 10:1 to 160:

1.

9. The method according to claim 1 or 3, wherein, The mass ratio of the pure cotton textile to the second catalyst is 2:1 to 10:

1.

10. The method according to claim 1 or 3, wherein, Based on the mass of the second catalyst, the nickel content is 0.5% to 5% by mass, and the tungsten carbide content is 10% to 50% by mass.

11. The method according to claim 1 or 3, wherein, The byproduct is selected from at least one of 1,2-propanediol, glycerol, 1,2-butanediol, erythrose, sorbitol, or mannitol, and the yield of the byproduct is from 4% to 17%.

12. The method according to claim 1 or 3, wherein, The pressure of the hydrogen atmosphere is 4 MPa to 8 MPa.

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