Catalyst for photodegradation of polyurethane, degradation method, preparation method and recovery method

Abstract

The invention discloses a catalyst for photodegradation of polyurethane, a degradation method, a preparation method and a recovery method. The invention provides a degradation method of polyurethane. The degradation method comprises the following step: irradiating a mixture of a catalyst, a solvent and polyurethane with light. According to the degradation method disclosed by the invention, the polyurethane material can be rapidly degraded in a heterogeneous phase, the time required for degrading the polyurethane material is greatly shortened, the treatment requirement of the polyurethane material is reduced, a bulk material can be directly degraded without disassembling, crushing and dissolving processes, and the material does not need to be crushed into powder and then degraded; and moreover, the conversion rate of waste polyurethane is high, and degradation products only comprise polyhydric alcohols and corresponding organic amines, and are high in purity and easy to separate.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of degradation and recycling of waste polyurethane products, in particular to a catalyst for photodegradation of polyurethane, a degradation method, a preparation method and a recycling method. BACKGROUND

[0002] Polyurethane (PU) is a widely used polymer material, whose structure is composed of flexible and rigid segments. This unique structure endows it with diverse properties. By adjusting key factors such as chemical composition, function, and molecular weight of monomers, polyurethane materials with significantly different characteristics can be developed. As a result, polyurethane has become one of the fastest growing polymers in the past nearly 80 years. In addition, with the regulation of processing conditions and apparent density, polyurethane has been successfully made into foam materials and widely used in many fields. Currently, polyurethane accounts for more than half of the total production of polymer foam materials.

[0003] So far, the production of polyurethane materials mainly relies on petrochemical-based raw materials. However, with increasing concerns about environmental sustainability, people are actively seeking alternatives to reduce the potential harm of waste polyurethane to the environment. Currently, natural raw materials are gradually gaining attention in the synthesis of polyurethane, but only polyols can achieve 100% biobased replacement. In contrast, biobased alternatives for isocyanates have not yet been fully commercialized. Covestro, a German company, has developed an isocyanate called Desmodur eco N7300, which has 70% carbon content from renewable resources, mainly extracted from starch of non-food plants. However, this material is only suitable for the production of hexamethylene diisocyanate (HDI) trimer. Therefore, for the current polyurethane materials mainly relying on limited and non-renewable resources, recycling and recycling have become one of the key issues to protect the environment, promote economic sustainability and innovation.

[0004] Several mature methods have been developed for the degradation and recycling of polyurethane, including physical, thermal treatment, chemical recycling, and some cutting-edge technologies still under exploration, such as biodegradation. Physical recycling (also known as mechanical recycling) mainly involves processing waste polyurethane materials into particles, flakes, or powders, which are then used in the automotive industry (e.g., as fillers), floor mats, or soundproofing materials. This method is relatively low-cost and easy to operate, but it is mainly suitable for thermoplastic polymers and has limited effectiveness for thermosetting polymers. Thermal-chemical recycling and energy recovery involve incinerating waste polyurethane materials to recover energy, such as for power generation or heating. However, the dust and emissions generated during the incineration process can pose serious environmental and health hazards. In addition to physical recycling, chemical recycling is one of the most widely used methods for polyurethane recycling. It includes hydrolysis, methanolysis, ammonolysis, acidolysis, glycolysis, and combinations of these methods. These chemical recycling processes are of great interest due to their technical feasibility, economic efficiency, and environmental friendliness.

[0005] Gu et al. proposed a highly efficient catalytic method for recycling and reusing waste polyurethane foam (Polymers 2023, 15, 2337). This method uses ethylene glycol (EG) and propylene glycol (PPG) as two-component alcoholysis agents, and through the synergistic action of double-metal catalyst (DMC) and alkali metal catalyst, the waste polyurethane foam is alcoholized. The reaction time is 2.5 h, and the reaction temperature is 160 ℃, at which the waste polyurethane foam can be completely alcoholized. Rafael Miguel-Fernández et al. developed a solvent depolymerization process that breaks the polymer chains of polyurethane under controlled process conditions (Polymers 2022, 14, 2936). This process requires grinding the waste polyurethane foam to a particle size of 5 mm, and under an alcoholysis time of 1.5 h, the best degradation effect can be achieved.

[0006] Patent CN116102783A discloses a polyurethane degradation technology that degrades polyurethane under the action of organic acid anhydride, and then treats the degradation products with alkali to recover polyols. However, this method still takes several hours to complete the degradation process, and further hydrolysis treatment is required after the initial degradation. In addition, although polyols can be recovered, amine degradation products are not effectively recovered.

[0007] Patent CN118271702A proposes a method of using metal-organic framework materials (MOFs) as a heterogeneous catalyst to degrade waste polyurethane and recover polyols. This method requires cutting or crushing large pieces of polyurethane before degradation, followed by an alcoholysis reaction at high temperature, which usually takes several hours.

[0008] Patent CN113354863A introduces a degradation technology for waste polyurethane. By mixing waste polyurethane with alcoholysis agent and alcoholysis aid, a polyol is obtained through a degradation reaction. This method requires the polyurethane material to be crushed first, and then stirred for several hours at high temperature to complete the degradation process.

[0009] Patent CN113828353A provides a recyclable catalyst for waste polyurethane recycling and a preparation method. The catalyst, alcoholysis agent and crushed waste polyurethane are mixed and heated, and then irradiated with 400-750 nm monochromatic light to obtain a polyol product. The polyurethane material needs to be crushed to a particle size of about 1 mm.

[0010] In addition, with the increasing emphasis on animal protection and other issues, synthetic leather has gradually become a popular consumer product. However, the large amount of water resources consumed and the pollution problems generated during its manufacture and use have placed a heavy burden on human health and the environment. In the context of circular economy, our pursuit of sustainability and environmental protection is becoming increasingly urgent, and we must start from the whole chain of "manufacturing, use, and recycling" to explore optimization solutions for each link. For a long time, the recycling of synthetic leather has been a challenge, mainly because it is composed of polyurethane (PU), polyethylene terephthalate (PET) and other materials, and the high peel strength between the layers makes it difficult to separate and recycle.

[0011] Since most of the chemical degradation of polyurethane is a heterogeneous reaction, it usually needs to be crushed into powder before degradation. This pretreatment step not only increases the demand for additional equipment and energy consumption, but also may produce dust pollution, and even has the risk of dust explosion. In addition, the chemical degradation of polyurethane usually needs to be carried out under high temperature or high pressure conditions, which makes the degradation rate slow and the product composition complex. Especially the separation of polyol and amine products is difficult, which further increases the energy consumption. At the same time, the severe reaction conditions may also cause equipment corrosion or produce toxic gases. Therefore, the current chemical degradation method is rarely effective for industrial production.

[0012] In summary, it is of great significance to develop a general, green, efficient, environmentally friendly and low-energy polyurethane degradation method that is suitable for polyurethane foam, polyurethane fiber (spandex), and synthetic leather, and the products of which are easy to separate, for promoting the sustainable development of polyurethane materials. SUMMARY

[0013] The main purpose of the present application is to provide a catalyst for photocatalytic degradation of polyurethane, a degradation method, a preparation method and a recovery method. The method can realize the degradation of waste polyurethane under the conditions of normal temperature, normal pressure and mild light, without the need to crush the blocky polyurethane material into powder in advance, without the need for stirring and additional heating, and can effectively recover high-purity polyols and amine products through simple post-processing. The method promotes the decomposition of isocyanate groups in polyurethane by exciting the catalyst with a light source, thereby generating recyclable chemical products. The photocatalytic degradation and recovery method provided by the present application only needs to attach a small amount of catalyst and solvent to the surface of the polyurethane (PU) material, and then irradiate the material surface with a light source for a short time, which can continuously degrade and recover the material, and is suitable for polyurethane materials of various shapes and sizes. The method not only has a wide application prospect, but also can provide an effective solution for the resource utilization of waste polyurethane, and meets the current requirements of green chemistry and sustainable development.

[0014] The present application provides a catalyst for degrading polyurethane; The catalyst comprises a loading component and a loading material; wherein the loading component is used to initiate and help complete the degradation of polyurethane; the loading material is used to improve the photocatalytic activity, improve the light source utilization rate, fix the catalyst, and the loading component is adsorbed on the loading material; the loading component and the loading material are added to the reaction system respectively, which can also produce the same catalytic effect, and the loading component is easy to absorb moisture and deliquesce or volatilize, so that the loading component is loaded on the loading material to prevent the loss of the loading component, which is more conducive to the storage and recovery of the catalyst, improves the specific surface area of the photocatalyst as a whole, and improves the photocatalytic activity and light source utilization rate; The loading component is one or more of an alkaline metal compound, an amine compound, an alcohol amine compound and an organic Lewis acid; The alkaline metal compound comprises a metal hydroxide, a metal alkoxide and a metal weak acid salt; The metal hydroxide is preferably one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide and cesium hydroxide.

[0015] The metal alkoxide is preferably sodium methoxide, potassium tert-butoxide, sodium tert-butoxide or sodium ethoxide.

[0016] The metal weak acid salt is preferably one or more of potassium acetate, sodium acetate, potassium carbonate, sodium carbonate and cesium carbonate.

[0017] The amine compound can be a tertiary amine compound, such as one or more of triethylamine, triethylene diamine and N,N-diisopropyl ethylamine.

[0018] The alcohol amine compound can be one or more of monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, diisopropanolamine, triisopropanolamine and methyldiethanolamine.

[0019] The organic Lewis acid can be zinc acetate, bismuth neodecanoate and / or stannous octoate.

[0020] The loading material is selected from a material with large specific surface area and adsorption effect, such as one or more of porous materials or multi-layer materials, such as graphite, carbon black, carbon fiber (CF), carbon nanotube (CNT), graphene, carbon molecular sieve, activated carbon, aerogel.

[0021] In a certain aspect, the loading material is a carbon-based material with high absorbance in the ultraviolet-infrared light band.

[0022] The particle size of the carbon black is 30-200 nm. The specific surface area of the carbon black is 45-1400 m 2 / g.

[0023] The specific surface area of the carbon fiber is preferably 12-16 m 2 / g, preferably nanometer carbon fiber.

[0024] The average diameter of the carbon nanotube is preferably 5-8 nm, the average length is preferably 8-20 μm, and the specific surface area is preferably 220-280 m 2 / g. The carbon nanotube (CNT) can be a multi-walled carbon nanotube.

[0025] The particle size of the graphene is preferably 7-12 μm, and the specific surface area is preferably 50-200 m 2 / g.

[0026] The graphene can be single-layer graphene.

[0027] The particle size of the carbon molecular sieve is preferably 0.8-1.4 mm, and the specific surface area is preferably 500-1800 m 2 / g.

[0028] The particle size of the activated carbon is preferably 5-10 μm, and the specific surface area is preferably 1800-3000 m 2 / g. The activated carbon can be activated carbon for supercapacitors.

[0029] The mass ratio of the loading component to the loading material can be 1:20-2:1.

[0030] The catalyst is composed of the loading component and the loading material, and the loading component is adsorbed on the loading material.

[0031] The application also provides a method for degrading polyurethane using a catalyst, comprising the following steps: The catalyst is dissolved in a solvent and mixed with the polyurethane. The mixture is irradiated with light to degrade.

[0032] The solvent is a mixture of water and polyhydric alcohol or polyhydric alcohol, the polyhydric alcohol is one or more of ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol, preferably ethylene glycol or / and diethylene glycol.

[0033] The light is one or more of ultraviolet light, visible light, and infrared light, preferably infrared light, more preferably infrared light of 780 nm-5 μm.

[0034] The irradiance of the light irradiation is greater than 0.05 W / cm 2 .

[0035] The solvent equivalent is less than 10:1 and greater than or equal to 1:10.

[0036] In a certain aspect, the degradation method can be carried out under the protection of an inert gas, such as nitrogen or argon. In a certain aspect, the degradation method can also be carried out under the protection of an oxidizing agent, such as oxygen. Under the protection of an inert gas, the degradation product will obtain more amine products.

[0037] The degradation method further comprises the following post-treatment steps after the reaction of the light irradiation is completed: after the reaction is completed, the reaction solution is filtered to remove the catalyst, and the degradation product polyhydric alcohol and organic amine are obtained.

[0038] The degradation method further comprises the following post-treatment steps after the reaction of the light irradiation is completed: after the reaction is completed, an organic solvent (such as a halogenated alkane organic solvent, or DCM) is added to the mixture to dilute; the reaction solution is filtered to remove the catalyst; the filtrate is extracted with water, and the obtained first organic phase product is added to an acid (such as hydrochloric acid, and further such as 0.5-2 N hydrochloric acid) to be acidified and then separated to obtain the second organic phase product and the second aqueous phase product, respectively; wherein the second organic phase product contains the degradation product polyhydric alcohol; an alkali (such as 1-5 M KOH) is added to the second aqueous phase product to adjust the pH to alkaline (such as 10-12), and then an organic solvent (such as a halogenated alkane organic solvent, and further such as DCM) is extracted; after the solvent of the extracted third organic phase product is removed, the degradation product organic amine is obtained, and the organic amine can be treated with phosgene to obtain isocyanate.

[0039] The present application also provides a preparation method of a catalyst for degrading polyurethane, which comprises the following steps: The support material is dissolved in solvent A to form a sol in solvent A, The support component is dissolved in solvent B and mixed with the sol to disperse the support component in the sol. Drying to obtain the catalyst.

[0040] The solvent A is conventionally selected according to the specific composition of the support material to dissolve the support material in the solvent A and form the sol. In some embodiments, the solvent A is an organic solvent, preferably an alcohol solvent, such as ethanol. In some embodiments, the mass ratio of the support material to the organic solvent A is less than 2:1, such as 1:5.

[0041] The solvent B is conventionally selected according to the support component. For example, when the support component is an inorganic base, the solvent B is water; when the support component is an alkaline metal compound, an amine compound, an alcohol amine compound, or an organic Lewis acid, the solvent B is methanol or ethanol. The support component is dissolved in the solvent B and then added (e.g., dropwise) to the sol. In some embodiments, the mass ratio of the support component to the solvent B is less than 2:1, such as 1:2.

[0042] The mixing operation can be a conventional mixing operation in the art, such as stirring; the dispersing operation can be a conventional dispersing operation in the art, such as ultrasonic treatment, stirring at room temperature, or stirring with heating; the operation should not destroy the structure of the support component. The stirring speed is 100-1000 rpm, preferably 300 rpm; the stirring time is 1-5 hours, such as 3 hours; the stirring temperature is 10-40℃, such as 25±1℃; the ultrasonic treatment time is 1-5 hours, such as 2 hours; the stirring time is 1-48 hours, such as 24 hours; and the drying is performed at 100-130℃, preferably 120℃±2℃.

[0043] The application also provides a method for recycling the catalyst for degrading polyurethane: After the degradation reaction is completed, the reaction solution is filtered, the obtained filter cake is washed, regenerated, and the recycled catalyst is obtained.

[0044] The regeneration operation is to dry, grind, and sieve the recycled catalyst, and then disperse the catalyst in solvent A again, mix, disperse, and dry the catalyst again with the solution of the support component.

[0045] The positive progress effect of the application is that the catalyst of the application has one or more of the following advantages: (1) The degradation of waste polyurethane materials is realized under mild light, normal temperature and normal pressure, which greatly reduces the time required for the degradation of waste polyurethane materials, shortens the time required for traditional high-temperature degradation from several hours to tens of minutes, and does not require additional heating or stirring during the reaction process, thereby reducing energy consumption and the reaction conditions are mild. (2) The bulk material can be directly degraded without the need to crush the material into powder for degradation, thereby reducing dust pollution and eliminating the risk of dust explosion.

[0046] (3) The conversion rate of waste polyurethane is high. (4) The degradation products are mainly polyols and MDA / TDA, which have high purity and are easy to separate.

[0047] (5) The catalyst used can be recycled: after being used for several cycles, the degradation rate of waste polyurethane can still reach more than 95%.

[0048] The amine compound degradation product described in the present application includes a mixture of diamino diphenyl methane (MDA) and polyphenyl polymethylene polyamine (polymerized MDA) or toluene diamine (TDA).

[0049] The "polyol" described in the present application can refer to a single polyol or a mixture of polyols. The polyol is, for example, a polyether polyol based on propylene oxide and ethylene oxide, a polyester polyol, a polycarbonate polyol, a polytetrahydrofuran, an acrylic polyol.

[0050] The "polyurethane" described in the present application refers to a material or article composed of or containing polyurethane as generally described in the art. The polyurethane includes one or more of diphenyl methane diisocyanate (MDI), polyphenyl polymethylene polyisocyanate (polymerized MDI), and toluene diisocyanate (TDI). For example, polyurethane foam, polyurethane leather, or polyurethane fiber, for example, polyurethane rigid foam or Haptex 4.0 polyurethane synthetic leather.

[0051] The term PU: polyurethane; EG: ethylene glycol; MDI: a mixture of diphenyl methane diisocyanate and polyphenyl polymethylene polyisocyanate; TDI: toluene diisocyanate; MDA: a mixture of diamino diphenyl methane and polyphenyl polymethylene polyamine; TDA: toluene diamine; DCM: dichloroalkane The particle size value described in the present application refers to the particle size of D50.

[0052] The catalyst equivalent described in the present application refers to the mass ratio of catalyst to polyurethane. Solvent equivalent as used herein refers to the mass ratio of polyurethane: solvent. Load component equivalent as used herein refers to the mass ratio of load component: polyurethane. Load material equivalent as used herein refers to the mass ratio of load material: polyurethane. Unless otherwise indicated, experimental methods in the present application are carried out according to conventional methods and conditions, or according to the instructions of the commercial suppliers.

[0053] Unless otherwise indicated, all percentages, parts, ratios, etc., are by weight. Those skilled in the art will appreciate that the actual sum of the components of a composition can suitably be 100%. When a range is given, it is intended to specifically disclose all ranges falling within the range, whether or not the ranges are expressly disclosed. When numerical ranges are given, the range is intended to specifically disclose all integers within the range, whether or not the integers are expressly disclosed. When a value is given as a range, it is intended to specifically disclose all values falling within the range, whether or not the values are expressly disclosed.

[0054] The terms "about," "approximately" when used in connection with a numerical value, generally mean the numerical value and all numerical values within experimental error (e.g., within a 95% confidence interval for a mean value) or within ±10% of the stated numerical value, or a broader range.

[0055] The terms "comprising," "including," "containing," and other similar terms are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. Those skilled in the art will appreciate that the terms "comprising" and "including" encompass the meaning of "consisting of." The expression "consisting of" excludes any element, step, or ingredient not specified.

[0056] The term "one or more" as used herein means one, two, three, four, five, six, seven, eight, nine, or more.

[0057] The term "and / or" as used herein encompasses both "and" and "or." The use of "and / or" in the context of a list of elements or components means that the elements or components are either all present or one or more of them are present. For example, A and / or B encompasses A, B, and A+B; A, B, and / or C encompasses A, B, C, A+B, A+C, B+C, and A+B+C.

[0058] In the present application, the term "plurality" means two or more, unless otherwise explicitly specified. Unless the context clearly indicates otherwise, "a" can encompass both singular and plural referents.

[0059] The above-mentioned preferred conditions can be combined arbitrarily without departing from the common knowledge in the art, thereby obtaining various preferred embodiments of the present application.

[0060] The catalyst and the method for degrading polyurethane provided by the present application are suitable for polyurethane of isocyanate system, especially for polyurethane of TDI and MDI system. The catalyst provided by the present application can degrade polyurethane into products including organic amine and / or polyhydric alcohol, which is the mark of the effect. DETAILED DESCRIPTION

[0061] The present application will be further illustrated by the following examples, but the present application is not limited to the scope of the examples.

[0062] Test method description: Recovery rate of MDA / TDA = mass of recovered MDA / TDA mixture / mass of MDA / TDA component in polyurethane x 100% Recovery rate of polyhydric alcohol = mass of recovered polyhydric alcohol mixture / mass of polyhydric alcohol component in polyurethane x 100% Conversion rate = (mass of polyurethane + mass of catalyst - mass of solid residue) / mass of polyurethane x 100% Purity of MDA / TDA = integral area of benzene ring characteristic peak at 6.5 ppm in HNMR of 20 mg standard MDA / TDA dissolved in 0.5 mL deuterated DMSO / integral area of benzene ring characteristic peak at 6.5 ppm in HNMR of 20 mg standard MDA / TDA dissolved in 0.5 mL deuterated DMSO x 100% 1 HNMR at 6.5 ppm Benzene ring characteristic peak integral area / 20 mg standard MDA / TDA dissolved in 0.5 mL deuterated DMSO 1 Integral area at 6.5 ppm in HNMR x 100% Purity of polyhydric alcohol = integral area of polyhydric alcohol characteristic peak at 1.0 ppm in HNMR of 20 mg recovered polyhydric alcohol dissolved in 0.5 mL deuterated DMSO / integral area of polyhydric alcohol characteristic peak at 1.0 ppm in HNMR of 20 mg polyhydric alcohol standard dissolved in 0.5 mL deuterated DMSO x 100% 1 HNMR at 1.0 ppm Polyhydric alcohol characteristic peak integral area / 20 mg polyhydric alcohol standard dissolved in 0.5 mL deuterated DMSO 1 Integral area at 1.0 ppm in HNMR x 100%.

[0063] Irradiance The energy distribution diagram of the light source used in the wavelength range of 400-2500 nm was measured by a fiber spectrometer, and the wavelength integral was measured in the wavelength range (unit W / cm 2 ). 1 H NMR was tested by 400M NMR Bruker Avance NEO 400.

[0064] PU(MDI) polyurethane material can be derived from waste refrigerator insulation material, waste car seat cushion, self-made polyurethane rigid foam; PU(TDI) polyurethane material is derived from waste mattress material, etc. The polyol content of waste refrigerator insulation material and waste car seat cushion is about 40%, and the MDI content is about 60%; the polyol content of waste mattress material is about 60%, and the TDI content is about 36%; PU(MDI) leather is derived from waste artificial leather bag, wherein PU accounts for about 70%, and the base material is cotton thread, accounting for about 30%, the polyol content in PU is about 40%, and the MDI content is about 60%; spandex fiber is derived from commercially available spandex fiber material, and the polytetramethylene ether glycol (PTMEG) content is about 78%, and the MDI content is about 19%.

[0065] The self-made polyurethane rigid foam material is derived from commercially available MDI and polyether polyol polymerized by the following formula (the parts are mass ratio): (1) Polyether polyol 4110 100 parts (source manufacturer: Shandong Jiaying Chemical Co., Ltd.); (2) Water 2.1 parts; (3) MDI Desmodur-44V20L 140 parts (source manufacturer: Shanghai Daiwei New Material Co., Ltd.); (4) LBA foaming agent 20 parts (source manufacturer: Honeywell (China) Co., Ltd.); (5) Catalyst BDMA (N,N-dimethylbenzylamine) 1 part; According to the proportion of the materials in the above formula, the proportion of each material in the polyurethane foam is calculated, and the yield of each recycled and degraded component is calculated: The mass of MDI and polyol condensation does not change, the mass of polyol in the foam accounts for 100 / (100+140+20+1+2.1)=38.0%, and the mass of MDI accounts for 140 / (100+140+20+1+2.1)=53.2%.

[0066] Preparation method of catalyst in example 1 The 10.0 g support material was dispersed in 50 mL absolute ethanol (solvent A) to form a homogeneous sol by ultrasonic dispersion technique. Subsequently, the support component dissolved in 10 mL solvent B was precisely added into the sol by micro-droplet pump, about 15-20 min for drop completion, and the solution was kept at 25±1 °C in a double-cylindrical jacketed reactor equipped with a temperature control system under nitrogen protection with stirring at 300 rpm for 3 hours, keeping the solution temperature at 25±1 °C. Then, the sol was transferred to an ultrasonic treatment device and ultrasonically treated for 2 hours in a nitrogen atmosphere to promote uniform adsorption. After continuous stirring at 25±1 °C for 24 hours, it was transferred to an oven at 120 °C±2 °C for drying for 6 hours, and finally ground to obtain the catalyst.

[0067] The catalysts in Table 1 below were prepared according to the above preparation method: Table 1

[0068] The support material can be selected: Table 2

[0069] Example 2 Polyurethane photocatalytic degradation Under normal temperature and pressure air environment, 0.1 g cat. A1 catalyst and 0.5 g ethylene glycol solvent were added into a container and mixed uniformly. 1.0 g PU (MDI) rigid foam (from waste refrigerator insulation material) was put in. The reaction container was placed under a light source (780 nm-5 μm near-infrared light source) for irradiation. The reaction system was irradiated with the light source for a certain time (more than 60 s). After the reaction was completed, 5 mL DCM was added for dilution and suction filtration, and the filter cake mainly consisted of catalyst. The filtrate was washed with 3x3 mL water to remove ethylene glycol, and the liquid was separated to obtain the first organic phase product and the first aqueous phase product. 2 mL 1 mol / L HCl was added to the first organic phase, stirred for 10 min, and then separated to obtain the second organic phase product and the second aqueous phase product. The second organic phase product was concentrated to obtain recovered polyol; the second aqueous phase product was added to 1 mL 5 mol / L KOH aqueous solution to adjust the pH to 10-12, and then 10 mL DCM was added for extraction. The third organic phase product obtained was concentrated to obtain recovered MDA.

[0070] The following examples, except for the parameters specifically noted, use the same experimental conditions as in Example 2. Light source screening, irradiation time screening, irradiance screening, solvent screening, catalyst screening, catalyst equivalent screening, solvent equivalent screening are carried out according to the above procedures, and the light irradiation conditions are compared with the conventional heating conditions (KOH is 3% of the mass of the polyurethane material), and the results are as follows: Example 3: Light source screening Table 3

[0071] Example 4: Irradiation time screening Table 4

[0072] Example 5: Irradiance screening Table 5

[0073] Example 6: Solvent screening The same polyurethane raw material and catalyst as in Example 2 are used, the catalyst equivalent is 1:10, the solvent equivalent is 1:1, the light source is a near-infrared light source with a wavelength of 780 nm-5 μm, the irradiance is 1.2 W / cm 2 , and the reaction time is 10 min. Table 6

[0074] Example 7: Catalyst screening The catalyst equivalent is 1:10, the solvent equivalent is 1:1, the light source is a near-infrared light source with a wavelength of 780 nm-5 μm, the irradiance is 1.2 W / cm 2 , and the reaction time is 10 min. Table 7

[0075] Example 8: Catalyst loading material content screening Table 8, in this example, KOH is used as the loading component, carbon black 1 is used as the loading material, the light source is a near-infrared light source with a wavelength of 780 nm-5 μm, the irradiance is 1.2 W / cm 2 , and the reaction time is 10 min.

[0076] Example 9: Catalyst equivalent and solvent equivalent screening Table 9

[0077] Example 10 Light and heating conditions From this example, it can be found that using the method of the present application, high-efficiency polyurethane degradation can still be achieved at room temperature.

[0078] Table 10

[0079] Example 11 Application of different polyurethane photocatalytic degradation In a container, 1.0 g of cat. A1 and 8.0 g of ethylene glycol were added and mixed uniformly. 10.0 g of different polyurethane materials shown in Table 11 below were put in. The reaction container was placed under an infrared lamp with a wavelength range of 780 nm-2.5 μm and an irradiance of 1.2 W / cm 2 After 10 min of irradiation, 50 mL of DCM was added for dilution and suction filtration, and the filter cake was mainly composed of carbon black catalyst. The filtrate was washed with 3 × 30 mL of water to remove ethylene glycol, and the liquid was separated. The first organic phase product and the first aqueous phase product were obtained. 20 mL of 1 mol / L HCl was added to the first organic phase, and after stirring for 10 min, the liquid was separated to obtain the second organic phase product and the second aqueous phase product. The second organic phase product was concentrated to obtain the recovered polyol; the second aqueous phase product was adjusted to pH=10~12 by adding 10 mL of 5 mol / L KOH aqueous solution, and then 50 mL of DCM was added for extraction. The obtained third organic phase product was concentrated to obtain the recovered MDA, and the product purity was measured. The treatment results are shown in Table 10.

[0080] According to Table 11, it can be found that using the method of the present application, high-efficiency degradation can be achieved for various types of polyurethane.

[0081] Table 11

[0082] Example 12 Study on the reaction efficiency of recovered catalyst The material ratio and operation were the same as in Example 11, and the polyurethane was derived from waste refrigerator insulation materials. The catalyst used was cat. A1 recovered for different times, and the treatment results are shown in Table 12.

[0083] According to Table 12, it can be found that using the method of the present application, the recovered catalyst can be repeatedly used.

[0084] Table 12

Claims

1. A catalyst for degrading polyurethane, characterized in that: The catalyst is a supported catalyst, comprising a supported component and a supported material; The supported component is used to catalyze the degradation of polyurethane; The supporting material is used to adsorb the supported components; Under light irradiation, the catalyst can catalyze the degradation of the polyurethane, and the degradation products include polyols and organic amines. The organic amines can be treated with phosgene to obtain isocyanates. The light includes one or more of the following: ultraviolet light with a wavelength of 200-400 nm, visible light with a wavelength of 400-780 nm, or infrared light with a wavelength greater than 780 nm.

2. The catalyst for degrading polyurethane as described in claim 1, characterized in that: The loading component is one or more of the following: alkali metal compounds, amine compounds, alkanolamine compounds, and organic Lewis acids; The loading material is a porous material or a multilayer material with adsorption properties.

3. The catalyst for degrading polyurethane as described in claim 2, characterized in that: The loading material includes one or more of graphite, carbon black, carbon fiber (CF), carbon nanotubes (CNT), graphene, carbon molecular sieve, activated carbon, and aerogel.

4. The catalyst for degrading polyurethane as described in claim 1, characterized in that: The mass ratio of the load component to the load material is 1:20-2:

1.

5. The catalyst for degrading polyurethane as described in claim 2, characterized in that: The alkaline metal compound includes one or more of metal hydroxides, metal alkoxides, and weak metal acid salts; The metal hydroxide includes one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, and cesium hydroxide; The metal alkoxide is one or more of sodium methoxide, potassium tert-butoxide, sodium tert-butoxide, or sodium ethoxide. The metal weak acid salt is one or more of potassium acetate, sodium acetate, potassium carbonate, sodium carbonate, and cesium carbonate; The amine compound is a tertiary amine compound; The alkanolamine compound is one or more selected from monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, and methyldiethanolamine; The organic Lewis acid is one or more of zinc acetate, bismuth neodecanoate, or stannous octoate.

6. The catalyst for degrading polyurethane as described in claim 1, characterized in that: The light includes infrared light in the range of 780 nm to 5 μm.

7. The catalyst for degrading polyurethane as described in claim 6, characterized in that: The irradiance of the light is greater than 0.05 W / cm². 2 .

8. A method for preparing a catalyst for degrading polyurethane as described in any one of claims 1 to 7, comprising the steps of: The loaded material is dissolved in solvent A, and then dispersed in solvent A to form a sol. The loaded component is dissolved in solvent B and mixed with the sol to disperse the loaded component in the sol. After drying, the catalyst is obtained.

9. A method for preparing a catalyst for degrading polyurethane as described in claim 8, characterized in that: Solvent A is an organic solvent.

10. A method for preparing a catalyst for degrading polyurethane as described in claim 8, characterized in that: The mass ratio of the loading material to solvent A is less than 2:1; The mass ratio of the loaded component to solvent B is less than 2:

1.

11. A method for degrading polyurethane using a catalyst, characterized in that, The catalyst is as described in any one of claims 1 to 7, and the degradation method comprises the following steps: The catalyst is dissolved in a solvent and then mixed with the polyurethane. The aforementioned mixture was degraded by irradiating it with light.

12. The degradation method as described in claim 10, characterized in that: The solvent is a mixture of water and a polyol or a polyol, wherein the polyol is one or more selected from ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, neopentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol.

13. The degradation method as described in claim 11 or 12, characterized in that: The degradation reaction is carried out under conditions of inert gas protection.

14. A method for recovering a catalyst for degrading polyurethane according to any one of claims 1 to 7, characterized in that: The catalyst is dissolved in a solvent and then mixed with the polyurethane. The aforementioned mixture was degraded by irradiation with light. After degradation is complete, dilute the mixture. The diluted mixture was filtered to obtain a filter cake and a filtrate; The obtained filter cake is washed and regenerated to obtain the recovered catalyst.

15. The recycling method as described in claim 14, characterized in that: The filtrate obtained by filtration was extracted with water to obtain the first organic phase product and the first aqueous phase product. Acid is added to the first organic phase product for acidification; After acidification, the product was separated to obtain the second organic phase product and the second aqueous phase product. The second organic phase product contains degradation product polyols; The pH of the second aqueous phase product is adjusted to alkaline, and then extracted with an organic solvent. The extracted third organic phase product, after removing the solvent, yields the degradation product organic amine. This organic amine can be treated with phosgene to obtain isocyanate.

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