Method for catalytically cracking plastic, cracking solution and application of cracking solution

Abstract

The invention relates to the technical field of plastic cracking and recycling, and discloses a method for catalytically cracking plastic, a cracking solution and application of the cracking solution. The method comprises the following steps: S1, mixing polyolefin plastic with water to obtain a dispersion liquid; s2, the dispersion liquid is subjected to a reaction in an oxygen environment; the reaction conditions are as follows: the pressure is 1.5 to 2 MPa, and the temperature is 130 to 180 DEG C. The method has high cracking efficiency, does not need an additional catalyst, is mild in reaction conditions, and can reduce the cost while ensuring the safety.

Description

Technical Field

[0001] This invention relates to the field of plastic pyrolysis and recycling technology, specifically to a method for catalytically pyrolyzing plastics. Furthermore, this invention also relates to a pyrolysis solution obtained by the method for catalytically pyrolyzing plastics and its applications. Background Technology

[0002] Plastics are widely used in modern society, becoming an indispensable material in daily life due to their lightweight, durability, economy, and versatility. However, plastics have also brought a series of environmental and ecological problems. Due to their slow degradation, waste plastics cause serious pollution to the environment. The emergence of microplastics, in particular, has further raised concerns about ecosystems and human health. Faced with these problems, the global community is actively seeking sustainable alternatives and promoting the development of plastic recycling and reuse technologies to mitigate the negative impacts of plastics on the planet. The widespread use of polyolefin plastics poses a serious threat to the environment and ecosystems due to waste polyolefin plastics. These plastic products have long degradation cycles, leading to the accumulation of large amounts of waste in soil and water bodies, which in turn affects the ecological environment and biological health. Strengthening plastic recycling and reuse, and reducing carbon emissions in the plastic production and processing chain, are urgent measures that need to be taken.

[0003] Currently, waste polyolefin plastics are mainly treated through mechanical recycling followed by landfilling, incineration as fuel, and chemical degradation and reuse. Landfilling not only wastes land resources but also pollutes the land and water systems, while incineration produces toxic and harmful gases and greenhouse gases. Chemical methods convert waste polyolefin plastics into virgin chemical substances or basic raw materials that can be reused to produce new plastics. However, most current chemical methods require high temperature and high pressure conditions, have poor safety, and consume a lot of energy. In particular, they require expensive catalysts, resulting in high economic costs. Often, the added value of the product is not much different from the economic cost required for the reaction. Furthermore, selective reactions or separation are not possible in mixed plastics, making large-scale application unlikely. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of poor safety or high cost of existing plastic pyrolysis methods, and to provide a method for catalytic pyrolysis of plastics, a pyrolysis liquid and its application. This method has high pyrolysis efficiency, does not require the use of additional catalysts, has mild reaction conditions, and can reduce costs while ensuring safety.

[0005] To achieve the above objectives, a first aspect of the present invention provides a method for catalytically pyrolyzing plastics, the method comprising:

[0006] S1. Mix polyolefin plastic and water to obtain a dispersion;

[0007] S2. The dispersion is reacted in an oxygen environment;

[0008] The reaction conditions include: oxygen pressure of 1.5-2 MPa and temperature of 130-180℃.

[0009] Preferably, the reaction conditions include: a temperature of 160-180℃, a stirring rate of 100-500 r / min, preferably 200-400 r / min, and a time of 1-6 h, preferably 3-6 h.

[0010] Preferably, the method further includes: crushing the polyolefin plastic into granules or flakes before mixing the polyolefin plastic and water.

[0011] Preferably, the method further includes: mixing plastic waste with water and collecting the plastic waste floating on the water surface, which is polyolefin plastic.

[0012] Preferably, the polyolefin plastic is polyethylene plastic and / or polypropylene plastic.

[0013] More preferably, the polyolefin plastic is polyethylene plastic.

[0014] Preferably, the method further includes: collecting the reaction solution obtained in step S2.

[0015] More preferably, the method further includes: separating the reaction solution and collecting the oily liquid.

[0016] A second aspect of the present invention provides a pyrolysis solution, which is prepared by the method provided in the first method described above.

[0017] Preferably, the lysis solution contains C4-C 30 Aliphatic dicarboxylic acids, aldehydes, and ketones.

[0018] A third aspect of the present invention provides the application of the pyrolysis solution provided in the second aspect above in the preparation of lubricating additives.

[0019] The fourth aspect of the present invention provides the application of the lysis solution provided in the second aspect above in the preparation of skin care products and / or hair conditioners.

[0020] The fifth aspect of the present invention provides the use of the pyrolysis solution provided in the second aspect above in the preparation of detergents and / or coatings.

[0021] The sixth aspect of the present invention provides the use of the lysis buffer provided in the second aspect above in the preparation of drug carriers and / or drug intermediates.

[0022] The method provided by this invention, through the above technical solution, first mixes polyolefin plastic with water to obtain a dispersion, and then reacts the dispersion in an oxygen environment. Controlling the oxygen pressure at 1.5-2 MPa and the temperature at 130-180℃ effectively improves the pyrolysis efficiency and conversion rate of the plastic, and can quickly and safely remove pollutants from polyolefin plastics. This solves the problem of difficult recycling of waste polyolefin plastics and provides an effective strategy for the economical recycling of polyethylene and polypropylene, with broad application prospects. Furthermore, this reaction can pyrolyze polyolefin plastics under mild conditions and convert them into high-value chemicals such as diacids, aldehydes, and ketones, with high safety and no need for additional catalysts, thus reducing pyrolysis costs. Attached Figure Description

[0023] Figure 1 This is an infrared image of the pyrolysis products of Example 1;

[0024] Figure 2 This is the proton spectrum of the pyrolysis product of Example 1;

[0025] Figure 3 This is the carbon spectrum of the pyrolysis product of Example 1;

[0026] Figure 4 This is a heteronuclear single quantum correlation (HSQC) diagram of the pyrolysis products of Example 1;

[0027] Figure 5 This is a high-resolution mass spectrum of the pyrolysis products of Example 1;

[0028] Figure 6 This is a test graph of the lubrication performance of the pyrolysis products of Example 1. The upper line represents the friction coefficient of 0.3-0.5 when no product is added, and the lower line represents the friction coefficient that is significantly reduced after the product is added, remaining at about 0.09. Detailed Implementation

[0029] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0030] As described above, the first aspect of the present invention provides a method for catalytically pyrolyzing plastics, the method comprising the following steps:

[0031] S1. Mix polyolefin plastic and water to obtain a dispersion;

[0032] S2. The dispersion is reacted in an oxygen environment;

[0033] The reaction conditions include: oxygen pressure of 1.5-2 MPa and temperature of 130-180℃.

[0034] According to the present invention, in step S1, the mixing can be carried out in any feasible manner, as long as a dispersion containing polyolefin plastic is obtained. Specifically, it can be carried out by shaking, ultrasound, etc. Preferably, the mixing is ultrasonic mixing. More preferably, the mixing conditions include: ultrasonic power of 150-250W and time of 12-18min. As a specific embodiment of the present invention, the plastic and water are mixed in a beaker and ultrasonically treated with a 200W ultrasonic machine at 100% power for 15 minutes.

[0035] In step S2, reacting the dispersion in an oxygen environment can be achieved by: injecting the dispersion into a sealed container, and then filling the sealed container with oxygen to form an oxygen environment, the amount of oxygen filling being such that the pressure in the sealed container is 1.5-2 MPa. The reaction temperature can be controlled by a reactor or oven. For example, the reaction container can be placed in a reactor or oven first, and then the reaction temperature can be set. There are two stirring methods in the reactor: (1) magnetic stirring, where a magnetic stir bar is placed in the reactor, and after the reaction instrument is turned on, the built-in magnetic stirring device drives the magnetic stir bar to rotate, thereby achieving stirring; (2) mechanical stirring, where the reactor lid is equipped with an integrated stirring paddle, and stirring is achieved by high-torque magnetic coupling mechanical stirring. Stirring with a stirring paddle is preferred.

[0036] The oxygen pressure can be 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2.0 MPa, or any value between any two of the aforementioned values. The temperature can be 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, or any value between any two of the aforementioned values.

[0037] While existing technologies disclose the use of oxygen pressure for plastic degradation, this degradation occurs in an anhydrous environment and has very low degradation efficiency. However, the inventors unexpectedly discovered during their research that first mixing polyolefin plastics with water to prepare a dispersion, and then reacting the dispersion in an oxygen environment at a controlled pressure of 1.5-2 MPa and a temperature of 130-180℃, can effectively improve the degradation efficiency and conversion rate of plastics. This allows for the rapid and safe removal of polyolefin plastic contaminants, solving the problem of difficult recycling of waste polyolefin plastics and providing an effective strategy for the economical recycling of polyethylene and polypropylene, with broad application prospects. Furthermore, this reaction can degrade polyolefin plastics under mild conditions, converting them into valuable chemicals such as diacids, aldehydes, and ketones, with high safety, and does not require additional catalysts, thus reducing degradation costs.

[0038] The method provided by this invention can also be used with different types of polyolefin products, and has good reactant versatility. It not only solves the problem of difficult pyrolysis and recycling of waste polyolefin plastics, but also solves the problem of mixed pyrolysis and recycling of waste polyolefin plastics from different sources and with different molecular weights.

[0039] The reaction time can be 1-20 hours. Preferably, the reaction conditions include: a temperature of 160-180°C, a stirring rate of 100-500 r / min, specifically 100 r / min, 200 r / min, 300 r / min, 400 r / min, 500 r / min, or any value between the two aforementioned values, preferably 200-400 r / min, more preferably 300 r / min; and a reaction time of 1-6 hours, specifically 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or any value between the two aforementioned values, preferably 3-6 hours, more preferably 5-6 hours.

[0040] Preferably, the method further includes: crushing the polyolefin plastic into granules or flakes before mixing the polyolefin plastic with water. By crushing the polyolefin plastic into granules or flakes, the polyolefin plastic can be more evenly dispersed in water, thereby improving the subsequent pyrolysis effect.

[0041] There is no particular limitation on the size of the broken particles or flakes, as long as they can be mixed with water to form a uniform dispersion. Preferably, the particle size of the particles or flakes is less than or equal to 2 cm.

[0042] Preferably, the method further includes: mixing plastic waste with water and collecting the plastic waste floating on the water surface, which is polyolefin plastic. This method can separate polyolefin plastic from plastic waste, and different pyrolysis methods can be used for different plastics to further improve the pyrolysis effect.

[0043] Preferably, the polyolefin plastic is polyethylene plastic and / or polypropylene plastic. The above method has a better pyrolysis effect on polyethylene plastic and / or polypropylene plastic.

[0044] Preferably, the polyolefin plastic is polyethylene plastic. Studies have found that the above method has a better pyrolysis effect on polyethylene plastic and a higher conversion rate.

[0045] Preferably, the method further includes collecting the reaction solution obtained in step S2. The above method can break down polyolefin plastics into valuable chemicals such as diacids, aldehydes, and ketones. The collected reaction solution has good application value and can be recycled.

[0046] The reaction solution obtained in step S2 can be collected by methods such as filtration or vacuum filtration.

[0047] According to the present invention, before mixing, the polyolefin plastic can be washed with water or ethanol to remove impurities adhering to the surface of the polyolefin plastic, thereby increasing the purity of the subsequent reaction solution.

[0048] Preferably, the method further includes concentrating the reaction solution. This results in a higher content of dicarboxylic acid in the obtained reactants, facilitating subsequent applications.

[0049] According to the present invention, the concentration process is vacuum distillation, and the conditions for vacuum distillation include a temperature of 60-80°C. This concentration process removes the solvent from the reaction solution without causing other side reactions, ensuring the purity of the resulting concentrate.

[0050] Secondly, the present invention provides a pyrolysis buffer prepared by the method described in the first aspect above. This pyrolysis buffer contains a high content of C4-C. 30 Aliphatic dicarboxylic acids have wide applications in the preparation of surfactants, skin care products, hair conditioners, lubricants, coatings, drug carriers, and pharmaceutical intermediates.

[0051] Preferably, the lysis solution contains C4-C 30 Aliphatic dicarboxylic acids, aldehydes, and ketones. Specifically, the lysis solution contains dicarboxylic acids and small amounts of aldehydes and ketones. The dicarboxylic acids include, but are not limited to, succinic acid, glutaric acid, adipic acid, pimelic acid, and octanoic acid.

[0052] Thirdly, this invention provides an application of the above-mentioned pyrolysis solution in the preparation of lubricants. Long-chain aliphatic dicarboxylic acids and their salts are used as components of lubricants, which can improve frictional properties, significantly reduce the coefficient of friction under certain conditions, and extend the service life of mechanical parts.

[0053] Fourthly, this invention provides an application of the above-mentioned lysis solution in the preparation of surfactants. Long-chain aliphatic dicarboxylic acids are commonly used in the manufacture of cosmetics and personal care products such as skin care products, shampoos, and conditioners due to their biocompatibility with skin and hair and their ability to emulsify and stabilize emulsions.

[0054] Fifthly, the present invention provides the use of the above-mentioned pyrolysis solution in the preparation of detergents and / or coatings. C4-C 30 Aliphatic diacids are the main raw materials for soap making. Their carbon chain structure gives soap good surface activity, enabling it to effectively disperse grease and dirt in water. Long-chain aliphatic diacids can also impart good adhesion and durability to soap, and can be used as ingredients in coatings and paints.

[0055] Sixthly, the present invention provides the use of the above-mentioned lysis buffer in the preparation of drug carriers and / or drug intermediates. Long-chain fatty acids have good applications in drug carriers and intermediates.

[0056] According to a particularly preferred embodiment of the present invention, a method for catalytically pyrolyzing plastics is provided, comprising the following steps:

[0057] S1. Crush the polyolefin plastic into granules or flakes, then mix it with water to obtain a dispersion;

[0058] S2. The dispersion is reacted in an oxygen environment. After the reaction is completed, the reaction liquid is collected and separated to collect the oily liquid.

[0059] The reaction conditions include: oxygen pressure of 1.5-2 MPa, temperature of 130-180℃, stirring rate of 100-500 r / min, and time of 1-6 h.

[0060] The above method can pyrolyze waste polyethylene and polypropylene plastics into low-molecular-weight, high-value chemicals under mild conditions, solving the problem of difficult recycling of waste polyolefin plastics and providing an effective strategy for the economical recycling of polyethylene and polypropylene. Furthermore, the method requires no catalysts or other additives, uses water as a dispersant, and is carried out at 130-180°C and an oxygen pressure of 1.5-2.0 MPa, directly converting PE and PP components into high-value-added chemicals. The conditions are mild, the steps are simple and efficient, and the economic cost is low. Moreover, the method has a high conversion rate and high oil product yield; for waste polyethylene plastic products, the oil product yield can reach 95% or more, and for waste polypropylene plastic products, the oil product yield can reach 60% or more. It is applicable to different types of polyethylene and polypropylene products and has good reactant universality. This invention not only solves the problem of difficult pyrolysis and recycling of waste polyolefin plastics, but also solves the problem of mixed pyrolysis and recycling of waste polyolefin plastics from different sources and with different molecular weights.

[0061] The present invention will be described in detail below through examples. In the following examples, all other reagents were commercially available.

[0062] Preparation of Pt / Al2O3: 0.25 g of Al2O3 powder was weighed and added to 25 mL of H2O and 332 μL of H2PtCl6·6H2O solution. The mixture was magnetically stirred for 1 h. After stirring, it was sonicated for 1 h. After sonication, the solid was filtered and dried at 60 °C overnight. After complete drying, it was reduced with 4% H2 at 300 °C for 2 h to obtain Pt / Al2O3 with a loading of 0.5 wt%.

[0063] Example 1

[0064] (1) The PE express packaging bag (weight average molecular weight is 2.5×10) 4 The powder was crushed to a size no larger than 2 cm. 300 mg of the powder was added to 15 mL of H2O and sonicated at 200 W for 15 minutes to obtain a dispersion.

[0065] (2) Transfer the dispersion to a high-pressure reactor, fill it with 1.5 MPa of high-purity oxygen, stir at 300 r / min, and raise the temperature to 160℃ at a rate of 5℃ / min and keep it at 5h.

[0066] (3) After the reaction reaches the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is then concentrated by vacuum distillation at 60°C to -0.1 MPa, and the brownish-yellow liquid product is collected.

[0067] The structure of the recovered brownish-yellow liquid product was characterized by NMR and IR spectrometry, see [reference]. Figures 1 to 4 . Figure 1 The middle can be 1712cm -1 A strong peak was observed at the point, which is attributed to the -COOH band in the carboxylic acid. 1 H-NMR showed a distinct peak at 11-13 ppm, corresponding to the active protons of carboxylic acids, while a weak peak at 9-10 ppm corresponded to the protons of aldehydes and ketones. 13 In C-NMR, a distinct characteristic peak corresponding to the carbonyl group (C) can be observed in the 170-210 ppm range, and the concentrated peak in the 170-180 ppm range indicates that the product is mainly a carboxylic acid or ester. However, 1 No obvious characteristic peaks for the ester-terminal methyl and methylene groups were found in the ¹H NMR, indicating that the product is mainly a carboxylic acid. The carbonyl C peak at 205-210 ppm is attributed to the carbonyl C groups of aldehydes and ketones, and small amounts of aldehydes and ketones are present in the product. Figure 4 Heteronuclear single quantum correlation (HSQC) indicates that the fatty chain -(CH2) n - In the range of 1.1-1.3 ppm ( 1 H-NMR) and 25-30ppm ( 13 α-carbonyl CH2 is visible in the range of 2.3-2.5 ppm (C-NMR). 1 H-NMR) and 30-40ppm ( 13 β-carbonyl CH2 is visible in the range of 1.4-1.6 ppm (C-NMR). 1 H-NMR) and 20-25ppm ( 13 Visible within the range of C-NMR. Figure 5High-resolution mass spectrometry showed that the peak positions were consistent with the characteristic peaks of diacids, for example, m / z = 117, 131, 145, 159, which correspond to succinic acid, glutaric acid, adipic acid, pimelic acid, and octanoic acid, respectively.

[0068] In this embodiment, the plastic conversion (mass loss) percentage after 5 hours of reaction was 88.5%, and the mass ratio of the liquid product to the converted PE express packaging bag was 0.97:1.

[0069] in,

[0070] m (imput) The mass of plastic added; m residue This represents the remaining mass of the plastic.

[0071] Example 2

[0072] (1) Take PE shopping bags (weight average molecular weight 3.9×10) 5 The powder was crushed to a size of no more than 2 cm (g / mol). 300 mg of the powder was added to 15 mL of H2O and sonicated at 200 W for 15 minutes to obtain a dispersion.

[0073] (2) Transfer the dispersion to a high-pressure reactor, fill it with 1.5 MPa of high-purity oxygen, stir at 300 r / min, and raise the temperature to 160°C at a rate of 5°C / min and maintain it for 4 h.

[0074] (3) After the reaction reaches the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is then vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60°C. The brownish-yellow liquid product is collected.

[0075] In this embodiment, the percentage of plastic conversion (mass loss) after 4 hours of reaction was 94.2%, and the mass ratio of liquid product to converted PE shopping bag was 0.99:1.

[0076] Example 3

[0077] (1) The PP dessert cup (weight-average molecular weight is 4.5×10) 5 The fragments were crushed (g / mol) to a size no larger than 2 cm. 300 mg of the fragments were added to 15 mL of H2O and sonicated at 200 W for 15 minutes to obtain a dispersion.

[0078] (2) Transfer the dispersion to a high-pressure reactor, fill it with 1.5 MPa of high-purity oxygen, stir at 300 r / min, and raise the temperature to 160℃ at a rate of 5℃ / min and keep it at 5h.

[0079] (3) After the reaction reaches the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is then vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60°C. The brownish-yellow liquid product is collected.

[0080] In this embodiment, the percentage of plastic conversion (mass loss) after 5 hours of reaction was 96.2%, and the mass ratio of liquid product to converted PP dessert cup was 0.54:1.

[0081] Example 4

[0082] (1) The PP drinking cup (weight-average molecular weight is 4.9×10) 5 The powder was crushed to a size of no more than 2 cm (g / mol). 300 mg of the powder was added to 15 mL of H2O and sonicated at 200 W for 15 minutes to obtain a dispersion.

[0083] (2) Transfer the dispersion to a high-pressure reactor, fill it with 1.5 MPa of high-purity oxygen, stir at 300 r / min, and raise the temperature to 160°C at a rate of 5°C / min and maintain it for 4 h.

[0084] (3) After the reaction reaches the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is then vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60°C. The brownish-yellow liquid product is collected.

[0085] In this embodiment, the percentage of plastic conversion (mass loss) after 4 hours of reaction was 89.8%, and the mass ratio of liquid product to the converted PP drinking cup was 0.55:1.

[0086] Example 5

[0087] (1) The PE express packaging bag (weight average molecular weight is 2.5×10) 4 g / mol), PE shopping bags (weight average molecular weight 3.9×10 5 g / mol), PP dessert cup (weight average molecular weight of 4.5×10⁻⁶ g / mol), 5 g / mol), PP drinking cup (weight average molecular weight of 4.9×10⁻⁶ g / mol), 5 The four types of fragments (g / mol) were crushed separately to ensure that the fragment size was no greater than 2 cm. The four types of fragments were mixed in equal proportions, and a total of 300 mg was added to 15 mL of H2O. The mixture was ultrasonically treated at 200 W for 15 minutes to obtain a dispersion.

[0088] (2) Transfer the dispersion to a high-pressure reactor, fill it with 1.5 MPa of high-purity oxygen, stir at 300 r / min, and raise the temperature to 160℃ at a rate of 5℃ / min and keep it at 5h.

[0089] (3) After the reaction reaches the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is then vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60°C. The brownish-yellow liquid product is collected.

[0090] The percentage of conversion (mass loss) of the mixed plastic after 5 hours of reaction was 91.8%, and the mass ratio of liquid product to converted plastic was 0.86:1.

[0091] Example 6

[0092] (1) The PE express packaging bag (weight average molecular weight is 2.5×10) 4 g / mol), PE shopping bags (weight average molecular weight 3.9×10 5 g / mol), PP dessert cup (weight average molecular weight of 4.5×10⁻⁶ g / mol), 5 g / mol), PP drinking cup (weight average molecular weight of 4.9×10⁻⁶ g / mol), 5 The four types of fragments (g / mol) were crushed separately to ensure that the fragment size was no greater than 2 cm. The four types of fragments were mixed in equal proportions, and a total of 300 mg was added to 15 mL of H2O. The mixture was ultrasonically treated at 200 W for 15 minutes to obtain a dispersion.

[0093] (2) Transfer the dispersion to a high-pressure reactor, fill it with 1.5 MPa of high-purity oxygen, stir at 300 r / min, and raise the temperature to 160°C at a rate of 5°C / min and maintain it for 3 h.

[0094] (3) After the reaction reaches the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is then vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60°C. The brownish-yellow liquid product is collected.

[0095] In this embodiment, the percentage of plastic conversion (mass loss) after 6 hours of reaction was 68.7%, and the ratio of the mass of liquid product to the mass of converted plastic was 0.92:1.

[0096] Example 7

[0097] (1) The PE express packaging bag (weight average molecular weight is 2.5×10) 4 g / mol), PE shopping bags (weight average molecular weight 3.9×10 5 g / mol), PP dessert cup (weight average molecular weight of 4.5×10⁻⁶ g / mol), 5 g / mol), PP drinking cup (weight average molecular weight of 4.9×10⁻⁶ g / mol), 5 The four types of fragments (g / mol) were crushed separately to ensure that the fragment size was no greater than 2 cm. The four types of fragments were mixed in equal proportions, and a total of 300 mg was added to 15 mL of H2O. The mixture was ultrasonically treated at 200 W for 15 minutes to obtain a dispersion.

[0098] (2) Transfer the dispersion to a high-pressure reactor, fill it with 1.8 MPa of high-purity oxygen, stir at 300 r / min, and raise the temperature to 160°C at a rate of 5°C / min and maintain it for 4 h.

[0099] (3) After the reaction reaches the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is then vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60°C. The brownish-yellow liquid product is collected.

[0100] In this embodiment, the percentage of plastic conversion (mass loss) after 4 hours of reaction was 95.9%, and the mass ratio of liquid product to converted plastic was 0.86:1.

[0101] Example 8

[0102] (1) The PE express packaging bag (weight average molecular weight is 2.5×10) 4 The powder was crushed to a size no larger than 2 cm. 300 mg of the powder was added to 15 mL of H2O and sonicated at 200 W for 15 minutes to obtain a dispersion.

[0103] (2) Transfer the dispersion to a high-pressure reactor, fill it with 1.5 MPa of high-purity oxygen, stir at 300 r / min, and raise the temperature to 180°C at a rate of 5°C / min and keep it at 5 h.

[0104] (3) After the reaction reaches the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is then vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60°C. The brownish-yellow liquid product is collected.

[0105] In this embodiment, the percentage of plastic conversion (mass loss) after 5 hours of reaction was 92.5%, and the mass ratio of liquid product to converted PE express packaging bag was 0.83:1.

[0106] Example 9

[0107] (1) The PE express packaging bag (weight average molecular weight is 2.5×10) 4 The powder was crushed to a size no larger than 2 cm. 300 mg of the powder was added to 15 mL of H2O and sonicated at 200 W for 15 minutes to obtain a dispersion.

[0108] (2) Transfer the dispersion to a high-pressure reactor, fill it with 2.0 MPa of high-purity oxygen, stir at 300 r / min, and raise the temperature to 160℃ at a rate of 5℃ / min and keep it at 5h.

[0109] (3) After the reaction reaches the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is then vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60°C. The brownish-yellow liquid product is collected.

[0110] In this embodiment, the percentage of plastic conversion (mass loss) after 5 hours of reaction was 96.4%, and the mass ratio of liquid product to converted PE express packaging bag was 0.95:1.

[0111] Example 10

[0112] (1) The PE express packaging bag (weight average molecular weight is 2.5×10) 4 The powder was crushed to a size no larger than 2 cm. 300 mg of the powder was added to 15 mL of H2O and sonicated at 200 W for 15 minutes to obtain a dispersion.

[0113] (2) Transfer the dispersion to a high-pressure reactor, fill it with 1.5 MPa of high-purity oxygen, stir at 300 r / min, and raise the temperature to 130℃ at a rate of 5℃ / min and maintain it for 16 h.

[0114] (3) After the reaction reaches the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is then vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60°C. The brownish-yellow liquid product is collected.

[0115] In this embodiment, the percentage of plastic conversion (mass loss) after 16 hours of reaction was 99.9%, and the mass ratio of liquid product to converted PE express packaging bag was 0.78:1.

[0116] Example 11

[0117] (1) PE plastic granules (weight average molecular weight of 9.7 × 10⁻⁶) 3 Take 300 mg of the fragments (g / mol) and add them to 15 mL of H2O. Sonicate the mixture at 200 W for 15 minutes to obtain a dispersion.

[0118] (2) Transfer the dispersion to a high-pressure reactor, fill it with 1.5 MPa of high-purity oxygen, stir at 400 r / min, and raise the temperature to 130℃ at a rate of 5℃ / min and maintain it for 16 h.

[0119] (3) After the reaction has reached the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is concentrated by vacuum distillation and the brownish-yellow liquid product is collected.

[0120] In this embodiment, the percentage of plastic conversion (mass loss) after 16 hours of reaction was 93.8%, and the mass ratio of liquid product to converted PE plastic particles was 0.91:1.

[0121] Comparative Example 1

[0122] PE express packaging bags (weight average molecular weight of 2.5×10) 4The PE express packaging bag fragments were crushed to a size no larger than 2 cm. 300 mg of the fragments were added to 15 mL of H2O to prepare a dispersion. The dispersion was transferred to a high-pressure reactor, which was filled with 1.5 MPa of high-purity oxygen. The mixture was stirred at 300 r / min and heated to 100 °C at a rate of 5 °C / min. The temperature was maintained for 5 h and allowed to cool naturally to room temperature. The reaction solution was collected and filtered. The filtrate was evacuated to -0.1 MPa and concentrated by vacuum distillation at 60 °C. No brownish-yellow liquid was observed, and the quality of the plastic did not change significantly.

[0123] Comparative Example 2

[0124] (1) The PE express packaging bag (weight average molecular weight is 2.5×10) 4 The PE express packaging bag fragments were crushed to a size no larger than 2 cm. 300 mg of the fragments were added to 15 mL of H2O to prepare a dispersion.

[0125] (2) The dispersion was transferred to a high-pressure reactor, filled with 0.5 MPa of high-purity oxygen, stirred at 300 r / min, and heated to 160 °C at a rate of 5 °C / min and held for 5 h. The temperature was then allowed to drop naturally to room temperature. The reaction solution was collected and filtered. The filtrate was evacuated to -0.1 MPa and concentrated by vacuum distillation at 60 °C. The percentage of plastic conversion (mass loss) after the reaction was 33.4%, and the mass ratio of the liquid product to the converted PE express packaging bag was 0.84:1.

[0126] Comparative Example 3

[0127] (1) The PE express packaging bag (weight average molecular weight is 2.5×10) 4 The PE express packaging bag fragments were crushed to a size no larger than 2 cm. 300 mg of the fragments were added to 15 mL of H2O to prepare a dispersion.

[0128] (2) The dispersion was transferred to a high-pressure reactor, air was introduced at 1.5 MPa, and the mixture was stirred at 300 r / min. The temperature was increased to 160℃ at a rate of 5℃ / min and maintained for 5 h. The temperature was then allowed to drop naturally to room temperature. The reaction solution was collected and filtered. The filtrate was vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60℃. The percentage of plastic conversion (mass loss) after the reaction was 10.4%, and the mass ratio of the liquid product to the converted PE express packaging bag was 0.87:1.

[0129] Comparative Example 4

[0130] (1) The PE express packaging bag (weight average molecular weight is 2.5×10) 4 The PE express packaging bag fragments were crushed to a size no larger than 2 cm. 300 mg of the fragments were added to 15 mL of H2O to prepare a dispersion.

[0131] (2) The dispersion was transferred to a high-pressure reactor, air was introduced at 1.5 MPa, and the mixture was stirred at 300 r / min. The temperature was increased to 160℃ at a rate of 5℃ / min and maintained for 16 h. The temperature was then allowed to drop naturally to room temperature. The reaction solution was collected and filtered. The filtrate was vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60℃. The percentage of plastic conversion (mass loss) after the reaction was 34.2%, and the mass ratio of the liquid product to the converted PE express packaging bag was 0.77:1.

[0132] Comparative Example 5

[0133] PE express packaging bags (weight-average molecular weight 2.5×10⁻⁶) 4 The sample was crushed (g / mol) to a size no larger than 2 cm. 300 mg of PE express packaging bag fragments were added to a high-pressure reactor, which was then filled with 1.5 MPa of high-purity nitrogen. The temperature was increased to 160 °C at a rate of 5 °C / min and maintained for 5 h. The temperature was then allowed to drop naturally to room temperature. The reaction solution was collected and filtered. The filtrate was then evacuated to -0.1 MPa and concentrated by vacuum distillation at 60 °C. No brownish-yellow liquid was observed, and the quality of the plastic did not change significantly.

[0134] Comparative Example 6

[0135] The PS cup cap was crushed to a size no larger than 2 cm. 300 mg of PS cup cap fragments were added to 15 mL of H2O to obtain a dispersion. The dispersion was transferred to a high-pressure reactor, and 1.5 MPa of high-purity oxygen was introduced. The reactor was stirred at 300 r / min and the temperature was increased to 160 °C at a rate of 5 °C / min and maintained for 5 h. The temperature was then allowed to drop naturally to room temperature. The reaction solution was collected and filtered. The filtrate was evacuated to -0.1 MPa and concentrated by vacuum distillation at 60 °C. No brownish-yellow liquid was observed, and the quality of the plastic did not change significantly.

[0136] Comparative Example 7

[0137] The PET water bottle was crushed to a size no larger than 2 cm. 300 mg of PET water bottle fragments were added to 15 mL of H2O to prepare a dispersion. The dispersion was transferred to a high-pressure reactor, and 1.5 MPa of high-purity oxygen was introduced. The mixture was stirred at 300 r / min and heated to 160 °C at a rate of 5 °C / min, and maintained at that temperature for 5 h. The mixture was then allowed to cool naturally to room temperature. The reaction solution was collected and filtered. The filtrate was then vacuum-distilled to -0.1 MPa and concentrated under reduced pressure at 60 °C. No brownish-yellow liquid was observed, and the quality of the plastic did not change significantly.

[0138] Comparative Example 8

[0139] (1) The PE express packaging bag (weight average molecular weight is 2.5×10) 4The powder (g / mol) was pulverized to a size no larger than 2 cm. 0.1 g of Al2O3 powder and 200 mg of fragments were added to 15 mL of H2O and sonicated at 200 W for 15 minutes to obtain a dispersion.

[0140] (2) Transfer the dispersion to a high-pressure reactor, fill it with 1.5 MPa of high-purity oxygen, stir at 300 r / min, and raise the temperature to 130℃ at a rate of 5℃ / min and maintain it for 16 h.

[0141] (3) After the reaction reaches the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is then vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60°C. The brownish-yellow liquid product is collected.

[0142] The percentage of plastic conversion (mass loss) after 16 hours of reaction in this comparative example was 80.1%, and the mass ratio of liquid product to converted PE express packaging bag was 0.77:1.

[0143] Comparative Example 9

[0144] (1) The PE express packaging bag (weight average molecular weight is 2.5×10) 4 The powder (g / mol) was pulverized to a size no larger than 2 cm. 0.1 g of Pt / Al2O3 powder and 200 mg of fragments were added to 15 mL of H2O and sonicated at 200 W for 15 minutes to obtain a dispersion.

[0145] (2) Transfer the dispersion to a high-pressure reactor, fill it with 1.5 MPa of high-purity oxygen, stir at 300 r / min, and raise the temperature to 130℃ at a rate of 5℃ / min and maintain it for 16 h.

[0146] (3) After the reaction reaches the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is then vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60°C. The brownish-yellow liquid product is collected.

[0147] The percentage of plastic conversion (mass loss) after 16 hours of reaction in this comparative example was 54.4%, and the mass ratio of liquid product to converted PE express packaging bag was 0.73:1.

[0148] Comparative Example 10

[0149] (1) The PE express packaging bag (weight average molecular weight is 2.5×10) 4 The powder (g / mol) was pulverized to a size no larger than 2 cm. 0.2 g of Pt / Al2O3 powder and 200 mg of fragments were added to 15 mL of H2O and sonicated at 200 W for 15 minutes to obtain a dispersion.

[0150] (2) Transfer the dispersion to a high-pressure reactor, fill it with 1.5 MPa of high-purity oxygen, stir at 300 r / min, and raise the temperature to 130℃ at a rate of 5℃ / min and maintain it for 16 h.

[0151] (3) After the reaction reaches the set time, the mixture is allowed to cool to room temperature naturally. The reaction solution is collected and filtered. The filtrate is then vacuumed to -0.1 MPa and concentrated by vacuum distillation at 60°C. The brownish-yellow liquid product is collected.

[0152] The percentage of plastic conversion (mass loss) after 16 hours of reaction in this comparative example was 46.9%, and the mass ratio of liquid product to converted PE express packaging bag was 0.90:1.

[0153] The main reaction parameters of the above embodiments and comparative examples are shown in Table 1.

[0154] Table 1

[0155]

[0156]

[0157]

[0158] According to literature reports, Weckhuysen et al. heated PE to 130°C under 3MPa pressure for 16 hours, but the conversion rate was low. Carbonization occurred at 150°C, which was not conducive to the reaction. In addition, the reaction conditions were demanding and the operation was difficult.

[0159] As shown in Table 1, the conversion rate and yield of the examples are superior to those of Comparative Examples 1-5, indicating that the method provided by the present invention, which first mixes polyolefin plastics with water to obtain a dispersion, and then reacts the dispersion in an oxygen environment, controlling the reaction pressure at 1.5-2 MPa and the temperature at 130-180°C, has a high pyrolysis efficiency. It can pyrolyze polyolefin plastics under mild conditions and convert them into high-value chemicals such as diacids, aldehydes, and ketones, with high safety and no need for additional catalysts, thus reducing pyrolysis costs. The conversion rate and yield of the examples are superior to those of Comparative Examples 6 and 7, indicating that the method provided by the present invention has good selectivity for polyolefin plastics. The inventors unexpectedly discovered during their research that adding a catalyst to the method provided by the present invention actually affects the pyrolysis effect (see Example 10 and Comparative Examples 8-10). This indicates that the method provided by the present invention does not require additional catalysts and has a higher pyrolysis effect compared to using catalysts. This may be because when a catalyst is added under pure oxygen conditions, the catalyst reacts with oxygen first, which is not conducive to the direct oxidation of the plastic.

[0160] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for catalytically pyrolyzing plastics, characterized in that, The method includes the following steps: S1. Mix polyolefin plastic and water to obtain a dispersion; S2. The dispersion is reacted in an oxygen environment; The reaction conditions include: oxygen pressure of 1.5-2 MPa and temperature of 130-180℃.

2. The method according to claim 1, characterized in that, The reaction conditions include: a temperature of 160-180℃, a stirring rate of 100-500 r / min, and a time of 1-6 h.

3. The method according to claim 1, characterized in that, The method further includes: crushing the polyolefin plastic into granules or flakes before mixing the polyolefin plastic with water; Preferably, the method further includes: mixing plastic waste with water and collecting the plastic waste floating on the water surface, which is polyolefin plastic.

4. The method according to claim 1, characterized in that, The polyolefin plastic is polyethylene plastic and / or polypropylene plastic, preferably polyethylene plastic.

5. The method according to any one of claims 1 to 4, characterized in that, The method further includes: collecting the reaction solution obtained in step S2; Preferably, the method further includes: separating the reaction solution and collecting the oily liquid.

6. A lysis buffer, characterized in that, The lysis buffer is prepared by the method according to any one of claims 1 to 5; Preferably, the lysis solution contains C4-C 30 Aliphatic dicarboxylic acids, aldehydes, and ketones.

7. The use of the pyrolysis solution according to claim 6 in the preparation of lubricating additives.

8. The use of the lysis buffer according to claim 6 in the preparation of skin care products and / or hair conditioners.

9. The use of the pyrolysis solution according to claim 6 in the preparation of detergents and / or coatings.

10. The use of the lysis buffer according to claim 6 in the preparation of drug carriers and / or drug intermediates.

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