Method for supercritical ethanol catalytic depolymerization and high-value disposal of waste wind power blades

Abstract

The application discloses a kind of waste wind power blade supercritical ethanol catalytic depolymerization high-value disposal method.The method comprises the following steps: using co-impregnation method is loaded on γ-Al2O3 Ni and Ru active component, γ-Al2O3, nickel nitrate hexahydrate and ruthenium chloride are dissolved in water and stirred sufficiently, precursor is calcined and activated to obtain Ru-Fe-Ni / γ-Al2O3 Catalyst;Waste wind power blade, catalyst and ethanol are put into batch reactor, sealed, purged with nitrogen, heated to ethanol reaches supercritical state;After reaction, solid phase and liquid phase are separated by suction filtration;Washing, suction filtration solid phase obtains glass fiber and recovered catalyst, glass fiber is combined with fly ash and slag to prepare fiber reinforced concrete brick, realize waste and waste joint resource utilization;Rotary evaporation is carried out on liquid phase to obtain recovered ethanol and high-quality oil, and recovered ethanol and catalyst can continue to be used in reaction kettle.The application can realize high-value and harmless disposal of waste wind power blade, and has good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization technology, specifically relating to a method for the high-value disposal of waste wind turbine blades through supercritical ethanol catalytic depolymerization. Background Technology

[0002] To effectively address global climate change and energy shortages, renewable energy sources such as wind power are developing rapidly. According to the Global Wind Energy Report, global wind power installed capacity has increased from 130GW in 2008 to 906GW in 2022, and is projected to reach 2127GW by 2030. The design lifespan of wind turbine blades is typically 20 to 25 years. With the rapid growth in installed wind turbine capacity, a large number of wind turbine blades will be decommissioned in the future, becoming solid waste. Forecasts indicate that the global decommissioning volume of wind turbine blades will reach 8.89 million tons in the next 20 years, of which 3.65 million tons will be decommissioned in China. Wind turbine blades are thin-shell structures made of composite materials, primarily glass fiber reinforced composite materials (resin matrix + glass fiber), fillers, and auxiliary materials. Fiber-reinforced composite materials account for more than 60% of the total blade mass. After decommissioning, wind turbine blades will generate a large amount of glass fiber reinforced epoxy resin composite material waste. This thermosetting composite material has extremely strong three-dimensional cross-linking properties, making it difficult to degrade, dispose of, and utilize as a resource. The disposal of decommissioned wind turbine blades has received high attention and has been listed as one of the "Nine Major Engineering and Technical Challenges" by the China Association for Science and Technology.

[0003] Currently, the main methods for recycling waste wind turbine blades include mechanical recycling, thermal recycling, and chemical recycling. Mechanical recycling primarily uses physical methods to crush, grind, or mill the composite material into powder, but this results in significant loss of the mechanical properties of the recovered glass fiber, leading to low value. Thermal recycling promotes the thermal decomposition of organic components in an oxygen-free environment, separating the glass fiber from the blade. However, the reaction temperature is high, significantly impacting the glass fiber and causing carbon deposits. Chemical recycling refers to the method of degrading and separating clean glass fiber from the polymers in waste blades through chemical reactions. Supercritical fluids have attracted much attention due to their advantages of low dielectric constant, low viscosity, high reactivity, excellent solubility, efficient mass transfer, and mild reaction conditions. Water is commonly used as a solvent due to its harmlessness; however, supercritical water has high pressure and temperature, and it reacts with metal cations on the glass fiber surface to form strong alkalis, causing significant damage to the glass fiber. Chemical recycling of waste wind turbine blades often involves the use of catalysts, but most are homogeneous liquid catalysts, which are difficult to recover and generally have limited effectiveness. Therefore, this invention proposes a method for the high-value disposal of waste wind turbine blades through supercritical ethanol catalytic depolymerization. This method utilizes a solid catalyst to catalytically depolymerize waste wind turbine blades in supercritical ethanol to recover glass fiber. Simultaneously, the catalyst's hydrodeoxygenation capability is used to obtain high-calorific-value oil, increasing the product's value. Both ethanol and the catalyst can be recycled and reused. Furthermore, considering the current problem of ash and slag disposal from waste incineration, the recovered glass fiber is used in combination with fly ash and slag to produce concrete bricks, achieving synergistic resource utilization of waste materials. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of low utilization rate and low value of existing waste wind turbine blades by providing a method for the high-value disposal of waste wind turbine blades through supercritical ethanol catalytic depolymerization. This method utilizes a bimetallic solid catalyst to catalytically depolymerize waste wind turbine blades in supercritical ethanol, recovering high-strength glass fibers while generating high-calorific-value oil, thus forming a green, pollution-free, and high-value utilization system.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a method for the high-value disposal of waste wind turbine blades through supercritical ethanol catalytic depolymerization, comprising the following steps:

[0006] γ-Al2O3 was stabilized in air at 600℃ for 6 hours; ferric nitrate nonahydrate (Fe(NO3)3·9H2O), nickel nitrate hexahydrate (Ni(NO3)2·6H2O), ruthenium chloride (RuCl3·xH2O) and γ-Al2O3 were mixed and then water (deionized water) was added, and the mixture was stirred at 45℃ until the impregnation was uniform; the mixture was then evaporated at 80℃ to a water content of 5% to 10% to obtain the precursor; wherein, the amount of ferric nitrate nonahydrate, nickel nitrate hexahydrate, ruthenium chloride and γ-Al2O3 added was such that the Ni and Fe loading on the γ-Al2O3 support after the reaction was 8wt% and 5wt%, respectively, and the Ru loading was 0.5wt% to 3wt%;

[0007] The precursor was dried at 105℃ for more than 6 hours to ensure it was fully dried, and then activated by calcination in a muffle furnace to obtain the Ru-Fe-Ni / γ-Al2O3 catalyst.

[0008] Take discarded wind turbine blades, add Ru-Fe-Ni / γ-Al2O3 catalyst and ethanol to an intermittent reactor, seal the reactor, and purge with nitrogen until the air in the sealed space (reactor) is removed to create an oxygen-free environment; the mass ratio of the discarded wind turbine blades, Ru-Fe-Ni / γ-Al2O3 catalyst and ethanol is 1:0.05:(4~10).

[0009] Raise the temperature in the reactor until the ethanol reaches a supercritical state, and maintain this temperature for 30-120 minutes; remove the reactor from the heating hood and cool it to room temperature.

[0010] The solid and liquid products were separated by vacuum filtration; the solid product was washed with dichloromethane to obtain glass fiber and washing liquid, and the washing liquid was filtered to obtain the recovered catalyst; the liquid product was rotary evaporated to obtain the recovered ethanol and oil product.

[0011] Furthermore, the precursor is activated by calcination at a temperature of 500°C, a heating rate of 10°C / min, and a calcination time of 5 hours.

[0012] Furthermore, it also includes cutting the waste wind turbine blades into strips, washing them, and air-drying them before adding the Ru-Fe-Ni / γ-Al2O3 catalyst and ethanol.

[0013] Preferably, the mass ratio of the waste wind turbine blades to ethanol is 1:4.

[0014] Furthermore, the temperature is increased until the ethanol reaches a supercritical state at a rate of 5-10℃ / min. Considering that stirring would damage the glass fiber, no stirring is performed. The reaction temperature is 260-280℃ and the reaction pressure is 7.5-9 MPa.

[0015] Preferably, the reaction temperature is 260°C and maintained for 60 minutes.

[0016] Furthermore, the cooling to room temperature specifically involves: firstly, accelerating the cooling process to below 150°C but above room temperature within 5 minutes (the reaction will not continue below 150°C), and then allowing it to cool naturally to room temperature.

[0017] Furthermore, the rotary evaporation temperature is 70°C (at this temperature, the main product obtained by rotary evaporation is ethanol).

[0018] Furthermore, it also includes: mixing cement, slag and washed fly ash in a mass ratio of 2:1:2, adding water at a water-to-solid ratio of 2:5 to form a slurry, adding glass fiber, wherein the mass ratio of glass fiber to slurry is 1:100-120, stirring evenly, pouring into a mold, sealing with a sealing film, and curing indoors for 2-3 days after molding to obtain fiber-reinforced concrete bricks.

[0019] Further preferably, the sealing molding time for glass fiber reinforced concrete bricks is 3 days, and the room temperature curing time is also 3 days.

[0020] Furthermore, the recovered catalyst (which can be recycled 8-10 times) and the recovered ethanol are recycled and added back to the waste wind turbine blades for reaction.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. It can efficiently depolymerize and recover glass fibers from waste wind turbine blades and convert them into high-calorific-value, high-quality oil without generating secondary pollution or waste. At the same time, the recovered glass fibers can be used in conjunction with fly ash and slag to make concrete bricks, which has significant economic and environmental benefits.

[0023] 2. Compared with water, ethanol has a lower critical point temperature and pressure when used as a solvent. The recovered glass fiber is clean and has little mechanical loss. At the same time, ethanol can undergo dehydrogenation reaction in the supercritical state, and the generated H free radicals can effectively collide with the macromolecular chain segments of the polymer. In addition, ethanol is non-toxic.

[0024] 3. Introducing Ni metal into the catalyst can promote bond breaking during the depolymerization process, making the reaction conditions milder. Ru metal's ability to hydrodeoxidize can effectively improve the quality of the oil, while Fe metal gives the catalyst high-temperature resistance and resistance to carbon deposits.

[0025] 4. The ethanol solvent and catalyst used in depolymerization can be recycled, which greatly reduces the cost of materials and makes it more economical. Attached Figure Description

[0026] Figure 1This is a flowchart illustrating the process of a method for the high-value utilization of waste wind turbine blades through supercritical ethanol depolymerization according to the present invention. Detailed Implementation

[0027] To illustrate in detail the technical solutions adopted by the present invention to achieve the intended technical objectives, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the embodiments of the present invention are not limited thereto.

[0028] The present invention provides a method for the high-value disposal of waste wind turbine blades via supercritical ethanol catalytic depolymerization, comprising the following steps:

[0029] 1) Stabilize γ-Al2O3 in air at 600℃ for 6h.

[0030] 2) A certain amount of ferric nitrate nonahydrate, nickel nitrate hexahydrate, ruthenium chloride, and γ-Al₂O₃ were placed in a beaker, deionized water was added, and the mixture was magnetically stirred at 45°C for 12 hours to ensure uniform impregnation. Then, most of the water was evaporated at 80°C (to a water content of 5%–10%) to obtain the precursor. Specifically, using a co-impregnation method to load Ni and Fe active components onto the support, the theoretically guaranteed metal loading ratio of γ-Al₂O₃ to Ni and Fe is 8 wt% and 5 wt%, respectively. Using a co-impregnation method to load Ru active components onto the support, the theoretically guaranteed metal loading ratio of γ-Al₂O₃ to Ru is 0.5 wt%–3 wt%.

[0031] 3) The precursor was dried in a drying oven at 105℃ for more than 6 hours to ensure that it was fully dried, and then activated by calcination in a muffle furnace to obtain the Ru-Fe-Ni / γ-Al2O3 catalyst.

[0032] 4) Cut the waste wind turbine blades into strips of 4-6cm in length, wash and air dry them for later use.

[0033] 5) Place the waste wind turbine blade sample and ethanol into an intermittent reaction vessel, seal the reaction vessel, and purge the air inside the reaction vessel with nitrogen to create an oxygen-free environment; wherein, the mass ratio of waste wind turbine blade, Ru-Fe-Ni / γ-Al2O3 catalyst and ethanol is 1:0.05:(4~10).

[0034] 6) Increase the temperature in the reactor to 260-280℃ and the pressure to 7.5-9MPa at a certain heating rate. After reaching the aforementioned reaction temperature and pressure, maintain this state for 30-120 minutes.

[0035] 7) After the residence time is up, remove the reactor from the heating hood and cool it to room temperature. Then filter to separate the solid phase (glass fiber) from the liquid phase.

[0036] 8) The solid phase is washed with dichloromethane to obtain clean glass fibers. The washing liquid is then filtered to obtain the recovered catalyst, which can be recycled. The liquid phase is rotary evaporated to obtain recovered ethanol and oil phase products. The recovered ethanol is then fed back into the reactor to participate in the depolymerization reaction.

[0037] 9) After washing, the glass fiber is trimmed and mixed with cement, slag and washed fly ash in proportion. The mixture is then poured into a mold, sealed with sealing film, and allowed to set. It is then cured indoors for 2-3 days.

[0038] This invention utilizes supercritical ethanol in conjunction with a Ru-Fe-Ni / γ-Al2O3 catalyst to catalyze the depolymerization of waste wind turbine blades, recovering high-strength glass fibers and high-calorific-value oil, achieving high-value utilization. Ethanol undergoes dehydrogenation in the supercritical state, generating H radicals that effectively collide with the macromolecular segments of polymers to form monomers such as bisphenol A and oligomers, while the glass fibers do not react. The Ni in the added trimetallic catalyst plays an excellent role in breaking carbon-nitrogen and ether bonds, promoting the depolymerization of amine-cured epoxy resins; the introduction of Ru enables the catalyst to perform hydrodeoxygenation, reducing phenols and increasing alkanes in the generated oil, resulting in quality comparable to diesel fuel; while the introduction of Fe improves the selectivity of light hydrocarbons and gives the catalyst high-temperature resistance and anti-carbon deposit properties, allowing for multiple recycling. The glass fibers recovered in step 8 have comparable thermal and sound insulation properties to virgin glass fibers, and due to the mild reaction conditions, their tensile strength is well preserved, making them valuable.

[0039] Example 1

[0040] 1. Place γ-Al2O3 in a muffle furnace and stabilize it in air at 600℃ for 6 hours.

[0041] 2. Weigh 5g γ-Al2O3, 8.046g ferric nitrate nonahydrate, 8.803g nickel nitrate hexahydrate and 0.455g ruthenium chloride, dissolve them in 60ml deionized water, and stir magnetically at 45℃ for 12h to ensure uniform impregnation. Then evaporate most of the water at 80℃ (to a water content of 5% to 10%) to obtain the precursor.

[0042] 3. The obtained precursor was dried in a drying oven at 105℃ for more than 6 hours to ensure that it was fully dried. Then it was placed in a muffle furnace and calcined at 500℃ for 5 hours to obtain a catalyst with a Ni loading of 8wt%, a Fe loading of 5wt%, and a Ru loading of 1wt%. The catalyst is represented as Ru-5Fe-8Ni / γ-Al2O3.

[0043] 4. Cut the discarded wind turbine blades into strips of 1×1×4cm, wash them with deionized water, and air dry them for 24 hours.

[0044] 5. Place 13g of waste wind turbine blade sample, 0.65g of Ru-5Fe-8Ni / γ-Al2O3 catalyst, and 52g of anhydrous ethanol into a batch reactor. Seal the reactor tightly and purge it with nitrogen to remove air. Increase the temperature in the reactor to 260℃ and the pressure to 7.8MPa at a heating rate of 8℃ / min. After reaching the desired temperature and pressure, maintain this state for 60min.

[0045] 6. After the residence time is up, remove the reactor from the heating jacket and cool it to room temperature in air with a fan. Then, separate the solid and liquid phases using vacuum filtration. Wash the solid product with dichloromethane and filter to obtain clean glass fiber and recovered catalyst. Rotary distillation of the liquid product yields recovered ethanol and high-calorific-value oil.

[0046] 7. Under these conditions, the resin degradation rate can reach 97.43%, and the recovered glass fiber has a tensile strength of 1859.87 MPa. GC-MS analysis shows that the main components of the oil phase product are alkanes, alkenes, and a small amount of phenols, with a calorific value of 39.64 MJ / kg, indicating extremely high value.

[0047] 8. Mix cement, slag, and fly ash in a ratio of 2:1:2, and water to solids in a ratio of 2:5 to form a slurry. Trim clean glass fiber and mix it with the slurry at a ratio of 1:120, stirring thoroughly. Pour the slurry into molds and seal with sealing film. Cure for 3 days until the aerated concrete bricks are formed, then cure indoors for another 3 days to obtain brick specimens.

[0048] Example 2

[0049] 1. Place γ-Al2O3 in a muffle furnace and stabilize it in air at 600℃ for 6 hours.

[0050] 2. Weigh 5g γ-Al2O3, 8.852g ferric nitrate nonahydrate, 9.685g nickel nitrate hexahydrate and 1.002g ruthenium chloride, dissolve them in 60ml deionized water, and stir magnetically at 45℃ for 12h to ensure uniform impregnation. Then evaporate most of the water at 80℃ (to a water content of 5% to 10%) to obtain the precursor.

[0051] 3. The obtained precursor was dried in a drying oven at 105℃ for more than 6 hours to ensure that it was fully dried. Then it was placed in a muffle furnace and calcined at 500℃ for 5 hours to obtain a catalyst with a Ni loading of 8wt%, a Fe loading of 5wt%, and a Ru loading of 2wt%. The catalyst was denoted as 2Ru-5Fe-8Ni / γ-Al2O3.

[0052] 4. Cut the discarded wind turbine blades into strips of 1×1×4cm, wash them with deionized water, and air dry them for 24 hours.

[0053] 5. Place 13g of waste wind turbine blade sample, 0.65g of 2Ru-5Fe-8Ni / γ-Al2O3 catalyst, and 52g of anhydrous ethanol into a batch reactor. Seal the reactor tightly and purge with nitrogen to remove air. Increase the temperature in the reactor to 270℃ and the pressure to 8.1MPa at a heating rate of 8℃ / min. After reaching the desired temperature and pressure, maintain this state for 60min.

[0054] 6. After the residence time is up, remove the reactor from the heating jacket and cool it to room temperature in air with a fan. Then, separate the solid and liquid phases using vacuum filtration. Wash the solid product with dichloromethane and filter to obtain clean glass fiber and recovered catalyst. Rotary distillation of the liquid product yields recovered ethanol and high-calorific-value oil.

[0055] 7. Under these conditions, the resin degradation rate can reach 98.43%, and the recovered glass fiber, measured by tensile strength, can reach 1789.46 MPa. GC-MS analysis of the oil phase product shows that the main components are alkanes, alkenes, and a small amount of phenols, with a calorific value of 39.94 MJ / kg, indicating extremely high value.

[0056] 8. Mix cement, slag, and fly ash in a ratio of 2:1:2, and water to solids in a ratio of 2:5 to form a slurry. Trim clean glass fibers and mix them with the slurry at a ratio of 1:100, stirring thoroughly. Pour the slurry into molds and seal with sealing film. Cure for 3 days until the aerated concrete bricks are formed, then cure indoors for another 3 days to obtain brick specimens.

[0057] As can be seen from the above examples, due to the mild reaction conditions, the glass fiber recovered from waste wind turbine blades retains good mechanical properties and can be used in building materials. Therefore, by combining it with fly ash and slag to produce aerated concrete bricks, the synergistic resource utilization of waste can be achieved. Simultaneously, the introduction of Ni, Ru, and Fe promotes depolymerization, improving the quality of biofuel and increasing the number of catalyst cycles. The recovered ethanol and catalyst can be further used in organic hydrothermal liquefaction reactions, reducing costs. This invention enables the harmless and high-value utilization of waste wind turbine blades.

[0058] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for the high-value disposal of waste wind turbine blades through supercritical ethanol catalytic depolymerization, characterized in that... Includes the following steps: γ-Al₂O₃ was stabilized in air at 600 °C for 6 h; ferric nitrate nonahydrate, nickel nitrate hexahydrate, ruthenium chloride, and γ-Al₂O₃ were mixed and then added to water, and stirred at 45 °C until uniform impregnation was achieved; the mixture was then evaporated at 80 °C to a water content of 5%–10% to obtain the precursor; wherein the amounts of ferric nitrate nonahydrate, nickel nitrate hexahydrate, ruthenium chloride, and γ-Al₂O₃ added were such that the Ni and Fe loadings on the γ-Al₂O₃ support after the reaction were 8 wt% and 5 wt%, respectively, and the Ru loading was 0.5 wt%–3 wt%; The precursor was dried at 105 °C for more than 6 hours and then activated by calcination to obtain the Ru-Fe-Ni / γ-Al2O3 catalyst. Take a discarded wind turbine blade, add Ru-Fe-Ni / γ-Al2O3 catalyst and ethanol, seal it, and purge it with nitrogen until the air in the sealed space is removed; the mass ratio of the discarded wind turbine blade, Ru-Fe-Ni / γ-Al2O3 catalyst and ethanol is 1:0.05:(4~10). Increase the temperature until the ethanol reaches a supercritical state, and maintain this state for 30-120 minutes; then cool to room temperature. The solid and liquid products were separated by vacuum filtration; the solid product was washed with dichloromethane to obtain glass fiber and washing liquid, and the washing liquid was filtered to obtain the recovered catalyst; the liquid product was rotary evaporated to obtain the recovered ethanol and oil product.

2. The method for high-value disposal of waste wind turbine blades via supercritical ethanol catalytic depolymerization according to claim 1, characterized in that, The precursor was activated by calcination at a temperature of 500 °C, a heating rate of 10 °C / min, and a calcination time of 5 h.

3. The method for high-value disposal of waste wind turbine blades via supercritical ethanol catalytic depolymerization according to claim 1, characterized in that, It also includes cutting the waste wind turbine blades into strips, washing and air-drying them before adding Ru-Fe-Ni / γ-Al2O3 catalyst and ethanol.

4. The method for high-value disposal of waste wind turbine blades via supercritical ethanol catalytic depolymerization according to claim 1, characterized in that, The mass ratio of the discarded wind turbine blades to ethanol is 1:

4.

5. The method for high-value disposal of waste wind turbine blades via supercritical ethanol catalytic depolymerization according to claim 1, characterized in that, The temperature is increased until the ethanol reaches a supercritical state at a rate of 5-10 °C / min without stirring. The reaction temperature is 260-280 °C and the reaction pressure is 7.5-9 MPa.

6. The method for high-value disposal of waste wind turbine blades via supercritical ethanol catalytic depolymerization according to claim 5, characterized in that, The reaction temperature was 260 °C, and the reaction was maintained for 60 min.

7. The method for high-value disposal of waste wind turbine blades via supercritical ethanol catalytic depolymerization according to claim 1, characterized in that, The cooling to room temperature process specifically involves: firstly, accelerating the cooling process to below 150°C and above room temperature within 5 minutes, and then allowing it to cool naturally to room temperature.

8. The method for high-value disposal of waste wind turbine blades via supercritical ethanol catalytic depolymerization according to claim 1, characterized in that, The rotary evaporation temperature is 70 ℃.

9. The method for high-value disposal of waste wind turbine blades via supercritical ethanol catalytic depolymerization according to claim 1, characterized in that, Also includes: Cement, slag, and washed fly ash are mixed in a mass ratio of 2:1:2, and water is added at a water-to-solid ratio of 2:5 to form a slurry. Glass fiber is then added, with a mass ratio of glass fiber to slurry of 1:100~120. The mixture is stirred evenly, poured into a mold, sealed, and cured indoors for 2-3 days to obtain fiber-reinforced concrete bricks.

10. The method for high-value disposal of waste wind turbine blades via supercritical ethanol catalytic depolymerization according to claim 1, characterized in that, The recovered catalyst and recovered ethanol are recycled and added back to the waste wind turbine blades for reaction.

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