A polylactic acid-based waste plastic catalytic hydrogenolysis system and catalytic hydrogenolysis method

Abstract

The application discloses a kind of polylactic acid-based waste plastic catalytic hydrogenolysis system and method, belong to waste plastic processing technical field, the hydrogenolysis system includes pulverizer, hydrogenolysis reaction kettle, pressure reducer, hydrogen separation system and rectifying column.The hydrogenolysis method first polylactic acid-based waste plastic is heated melt liquefaction in hydrogenolysis reaction kettle, and the polylactic acid macromolecule after liquefaction occurs cracking reaction under the action of hydrogenolysis catalyst, and a large number of unsaturated lactic acid and active C3 intermediate are generated, then by catalytic hydrogenation and reconstitution reaction generate butyl propionate, hexyl propionate and other chemical products.The problems of low product yield and complex components existing in the existing pyrolysis process are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of waste plastic treatment, and particularly relates to a polylactic acid-based waste plastic catalytic hydrogenolysis system and method. BACKGROUND

[0002] Polylactic acid (PLA) is a renewable bioplastic, but the overall recovery rate of PLA-based waste plastics is still low, and a large amount of PLA-based waste plastics cannot be recycled and utilized, causing serious environmental pollution and great resource waste.

[0003] At present, waste plastics are mainly recycled by physical or chemical methods, mainly including landfill technology, incineration technology and recycling technology. However, both incineration technology and landfill technology can cause serious damage to the environment. Although recycling technology has environmental potential, due to the large number of plastic types, different types of plastics often need to go through complex classification and processing procedures, resulting in low efficiency. In addition, problems such as molecular chain breakage, degradation and impurity residue are prone to occur during the recycling process, which significantly reduces the mechanical properties and durability of the recycled plastics, resulting in poor performance of the products after recycling. Therefore, the above-mentioned recycling technologies cannot realize the efficient utilization of waste plastics.

[0004] PLA-based waste plastics can also be treated by biodegradation, that is, using degradable microorganisms and enzymes in the environment to degrade PLA, but PLA products are difficult to be completely degraded by microorganisms in a short period of time under natural conditions. Therefore, it is increasingly urgent to find a green PLA-based waste plastic recycling technology.

[0005] Pyrolysis process is a chemical conversion process of waste plastics. Pyrolysis process converts waste plastics into pyrolysis gas and pyrolysis oil under high-temperature anaerobic conditions, and the pyrolysis oil is cooled into liquid oil by a cooling system. Pyrolysis treats waste plastics by anaerobic thermal cracking, providing a harmless and efficient plastic resource utilization method with good cost performance and conversion rate. However, although pyrolysis process has significant advantages, it still faces the problems of low pyrolysis oil yield and poor oil quality in actual application. These shortcomings are mainly due to the limitation of the adaptability of the existing process to raw materials, the uneven control of temperature and residence time in the pyrolysis process, and the difficulty in completely inhibiting secondary cracking and other side reactions, thereby reducing the yield of liquid products, complicating the components and reducing the stability. For PLA-based waste plastics, pyrolysis process is still the main way to degrade PLA-based waste plastics. Pyrolysis process can convert PLA into value-added products with low energy input, realizing the efficient upgrading of PLA-based waste plastics, but a pyrolysis process with high selectivity for resource utilization has not been developed. SUMMARY

[0006] The application provides a polylactic acid-based waste plastic catalytic hydrogenolysis system and method to solve the problems of low product yield and complex components in the existing pyrolysis process.

[0007] In order to achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0008] In the first aspect, the application provides a polylactic acid-based waste plastic catalytic hydrogenolysis system, which comprises a pulverizer, a hydrogenolysis reactor, a pressure reducer, a liquid-phase delivery pump, a hydrogen separation system and a rectifying column.

[0009] The outlet of the pulverizer is connected with the solid-phase feeding port of the hydrogenolysis reactor.

[0010] The hydrogenolysis reactor comprises a reactor body, a stirring device, a catalyst fixed bed, a temperature and pressure control device and a heating jacket, the stirring blades of the stirring device and the catalyst fixed bed are located in the reactor body, the heating jacket is wrapped outside the reactor body, and the temperature and pressure control device is electrically connected with the heating jacket.

[0011] The reactor body is provided with a solid-phase feeding port, a gas-phase feeding port, a gas-phase discharging port and a liquid-phase discharging port.

[0012] The gas-phase discharging port is connected with the inlet of the pressure reducer, the outlet of the pressure reducer is connected with the inlet of the hydrogen separation system, and the outlet of the hydrogen separation system is connected with the gas-phase feeding port.

[0013] The liquid-phase discharging port is connected with the inlet of the rectifying column.

[0014] Further, the hydrogen separation system comprises a drying tank, a cold box, a hydrogen storage tank and a compressor, the inlet of the drying tank is connected with the outlet of the pressure reducer, the outlet of the drying tank is connected with the inlet of the cold box, the outlet of the cold box is connected with the inlet of the hydrogen storage tank, the outlet of the hydrogen storage tank is connected with the inlet of the compressor, and the outlet of the compressor is connected with the gas-phase feeding port.

[0015] Further, the rotating track of the stirring blades of the stirring device is tangent to the inner surface of the catalyst fixed bed.

[0016] In the second aspect, the application provides a polylactic acid-based waste plastic catalytic hydrogenolysis method based on the polylactic acid-based waste plastic catalytic hydrogenolysis system, which comprises the following steps:

[0017] Step 1: The polylactic acid-based waste plastics are sent into a hydrogenolysis reactor after being crushed and sieved by a crusher, and H2 is introduced into the hydrogenolysis reactor; the polylactic acid-based waste plastics are heated and liquefied in the hydrogenolysis reactor, and the ester bond of the unsaturated polylactic acid macromolecule is broken under the action of the hydrogenolysis catalyst and H2 to generate saturated small molecule lactic acid and active C3 intermediates, and then the saturated small molecule lactic acid and the active C3 intermediates are generated by catalytic hydrogenation and reconfiguration to generate hydrogenolysis oil, hydrogenolysis gas and H2O; the hydrogenolysis catalyst is a Pt supported catalyst, and the carrier is Nb2O5;

[0018] Step 2: The hydrogenolysis gas and the residual H2 in the hydrogenolysis reaction are sent into a cold box after being depressurized and dried, and the hydrogenolysis gas and H2 are separated by a cryogenic separation method.

[0019] The mixture of the hydrogenolysis oil and water is separated into water, hexyl propionate and butyl propionate.

[0020] Further, in step 1, the mass ratio of the polylactic acid-based waste plastics to the hydrogenolysis catalyst is 1.

[0021] Further, in step 1, the mass percentage of Pt in the hydrogenolysis catalyst is 1% to 10%.

[0022] Further, in step 1, the hydrogenolysis reaction conditions include that the hydrogenolysis reaction temperature is 250 DEG C to 300 DEG C, the hydrogenolysis reaction pressure is 1 MPa to 6 MPa, and the hydrogenolysis reaction time is 2 hours to 12 hours.

[0023] Further, in step 1, during the hydrogenolysis reaction, the stirring rate of the stirring device is 1000 r / min to 3000 r / min.

[0024] Further, in step 2, after the hydrogenolysis gas and H2 are separated, the separated H2 is sent into a hydrogen storage tank for storage, and the stored H2 is compressed by a compressor and used as the reaction gas for the hydrogenolysis reaction.

[0025] Further, in step 2, the mixture of the hydrogenolysis oil and water is separated into components by rectification, and during the rectification, the boiling point of the light component is ≤75 DEG C, and the boiling point of the heavy component is > 140 DEG C.

[0026] Compared with the prior art, the present application has at least the following beneficial technical effects:

[0027] The present invention provides a polylactic acid-based waste plastic catalytic hydrogenolysis system, which, through reasonable unit integration, achieves efficient resource regeneration while also possessing several practical advantages: relying on the fixed catalyst bed built into the distillation column and reactor, it significantly reduces equipment investment; operation and maintenance are convenient, the temperature and pressure control device can monitor and adjust process parameters in real time, the hydrogenolysis catalyst is easy to fill and replace, and the gas-liquid phase outlet layout is reasonable, reducing manual intervention and daily maintenance workload.

[0028] Meanwhile, by fixing the hydrogenolysis catalyst in the hydrogenolysis reactor through a catalyst fixed bed, it is easy to fill and separate, and can be recycled. This avoids energy-consuming operations such as traditional centrifugal separation. Combined with the hydrogenation reaction being carried out under relatively mild conditions, the overall energy consumption is low.

[0029] Furthermore, the combined use of cryogenic separation and compressors enables efficient recovery and recycling of hydrogen, significantly reducing the consumption of external energy and raw materials. During the reaction process, the hydrogen can be purified and compressed and then returned to the catalytic hydrogenolysis system for reuse, demonstrating strong resource recycling capabilities, effectively improving economic efficiency, and highlighting the environmental benefits and sustainable operation capabilities of the catalytic hydrogenolysis system.

[0030] This invention provides a method for the catalytic hydrogenolysis of polylactic acid (PLA)-based waste plastics. First, the PLA-based waste plastics are melted and liquefied. The liquefied PLA macromolecules undergo a cracking reaction under the action of a hydrogenolysis catalyst, generating a large amount of unsaturated lactic acid and active C3 intermediates. Subsequently, catalytic hydrogenation and reconstruction reactions produce butyl propionate, hexyl propionate, hydrogenolysis gas, and water. During the reaction, a cryogenic separation method is used to separate and store the hydrogenolysis gas and H2. The stored H2 can be recycled as a reaction gas for the hydrogenolysis reaction, saving H2 resources and achieving both economic and environmental benefits.

[0031] Furthermore, the mass ratio of polylactic acid-based waste plastics to hydrogenolysis catalyst is (1~10):1 to ensure highly efficient catalytic hydrogenolysis activity.

[0032] Furthermore, the Pt mass percentage in the hydrogenolysis catalyst is 1%~10%, which effectively controls costs while ensuring catalytic performance and meets the economic requirements of industrial applications.

[0033] Furthermore, by coordinating and controlling the hydrogenolysis catalyst, hydrogenolysis temperature, pressure, and reaction time, this invention effectively guides the reaction pathway and product distribution under relatively mild reaction conditions. This not only significantly improves the selectivity and yield of high-value-added products such as butyl propionate, but also suppresses side reactions such as excessive cracking and coking, thereby ensuring product quality while improving the economic efficiency of the entire process.

[0034] Furthermore, during the hydrogenolysis reaction, the stirring rate of the stirring device is 1000 r / min ~ 3000 r / min, which helps to fully mix the reactants, improves the contact efficiency between hydrogen and the substrate, and thus accelerates the reaction process.

[0035] Furthermore, after separating the hydrogen decomposition gas and H2, the separated H2 is sent to a hydrogen storage tank for storage. The stored H2 is compressed by a compressor and used as the reaction gas for the hydrogen decomposition reaction, thereby realizing the recycling of H2 and improving the utilization rate of H2.

[0036] Furthermore, the mixture of hydrogenated oil and water is separated by distillation. During distillation, the boiling point of the light component is ≤75 ℃, and the boiling point of the heavy component is >140 ℃. This efficient and thorough separation of the light component, water, and heavy component ensures the purity and quality of the products at the top and bottom of the column. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a polylactic acid-based waste plastic hydrogenolysis system provided by the present invention.

[0038] In the attached diagram: 1-Pulverizer; 21-Solid inlet; 22-Gas inlet; 23-Gas outlet; 24-Stirring device; 25-Catalyst fixed bed; 26-Temperature and pressure control device; 27-Heating jacket; 28-Liquid outlet; 3-Pressure reducer; 4-Drying tank; 5-Cold box; 6-Hydrogen storage tank; 7-Compressor; 8-Liquid phase transfer pump; 9-Distillation column; 10-Exhaust valve; 11-Inlet valve. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the invention.

[0040] Reference Figure 1 A polylactic acid-based waste plastic catalytic hydrogenolysis system includes a crusher 1, a hydrogenolysis reactor, a pressure reducer 3, a drying tank 4, a cold box 5, a hydrogen storage tank 6, a compressor 7, a liquid phase transfer pump 8, and a distillation column 9.

[0041] The hydrogenolysis reactor includes a reactor body, a stirring device 24, a catalyst fixed bed 25, a temperature and pressure control device 26, and a heating jacket 27. A solid phase inlet 21 is located at the top of the reactor body, a gas phase inlet 22 and a gas phase outlet 23 are located at the upper part of the reactor body, and a liquid phase outlet 28 is located at the bottom of the reactor body. Positioning the liquid phase outlet 28 at the bottom of the reactor body facilitates the discharge of liquid products. The stirring motor in the stirring device 24 is located outside the reactor body, while the stirring blades are located in the lower middle part of the reactor body. This stirs the substances within the reactor body, ensuring the uniformity of the liquefied plastic during the reaction. The rotation trajectory of the stirring blades is tangential to the inner surface of the catalyst fixed bed 25, which is conducive to the full occurrence of the hydrogenolysis reaction. The catalyst fixed bed 25 is fixed to the inner wall of the reactor body and is used to fill the hydrogenolysis catalyst, facilitating catalyst replacement and the separation of liquid products.

[0042] The gas phase outlet 23 at the top of the hydrogenolysis reactor is connected to the inlet of the pressure reducer 3 via a gas phase outlet pipe, which is used to send the gas phase product into the hydrogen separation system. An exhaust valve 10 is installed on the gas phase outlet pipe. The hydrogen separation system includes a drying tank 4, a cold box 5, a hydrogen storage tank 6, and a compressor 7. The outlet of the pressure reducer 3 is connected to the inlet of the drying tank 4, the outlet of the drying tank 4 is connected to the inlet of the cold box 5, the outlet of the cold box 5 is connected to the inlet of the hydrogen storage tank 6, the outlet of the hydrogen storage tank 6 is connected to the inlet of the compressor 7, and the outlet of the compressor 7 is connected to the gas phase inlet 22 via a gas phase feed pipe. An inlet valve 11 is installed on the gas phase feed pipe.

[0043] A heating jacket 27 covers the outside of the reactor body and is electrically connected to the temperature and pressure control device 26, together forming a control unit for the reaction conditions. The control unit dynamically adjusts the opening of the inlet valve 11 or the exhaust valve 10 by acquiring real-time signals from the pressure sensor installed inside the reactor and combining this with the temperature, pressure, and time of the hydrogenolysis reaction. This controls the outflow of H2 feed or gaseous products, achieving stable and precise control of the reaction system pressure. Simultaneously, the heating jacket 27 adjusts its heating power under the command of the temperature and pressure control device 26 to accurately maintain the reaction temperature.

[0044] The discharge port of the pulverizer 1 is connected to the solid feed port 21 of the hydrogenolysis reactor via a pipeline. The liquid discharge port 28 is connected to the inlet of the liquid transfer pump 8, and the outlet of the liquid transfer pump 8 is connected to the feed port of the distillation column 9 via a pipeline, so that the liquid product is sent into the distillation column 9 to separate the liquid components.

[0045] The workflow of this polylactic acid (PLA)-based waste plastic catalytic hydrogenolysis system is as follows: PLA-based plastic raw materials from the waste plastic dump are fed to a crusher 1 for crushing and screening. The crushed and screened PLA-based waste plastics are used as raw materials for the hydrogenolysis reaction and enter the hydrogenolysis reactor through the solid inlet 21 at the top of the reactor for catalytic hydrogenolysis, yielding a gaseous mixture and a liquid product—hydrogenolysis oil. The gaseous mixture includes the gaseous product hydrogenolysis gas and the residual H2 from the catalytic hydrogenolysis. The catalyst fixed bed 25 is filled with hydrogenolysis catalyst and can achieve the separation of the hydrogenolysis catalyst from the liquid product. During the catalytic hydrogenolysis process, a temperature and pressure control device 26 controls the heating jacket 27 to control the temperature of the hydrogenolysis reactor by electric heating, while simultaneously detecting and controlling the internal pressure of the hydrogenolysis reactor. The gaseous mixture contains a large amount of H2 and is discharged from the gaseous outlet 23 at the top of the reactor through a pressure reducer 3 and then sent to a drying tank 4 for drying. The dried gaseous mixture enters a cold box 5 for cryogenic separation to obtain hydrogenolysis gas and H2. The separated H2 can be stored in hydrogen storage tank 6. When hydrogenolysis reaction is required, H2 is compressed by compressor 7 and enters hydrogenolysis reactor through gas inlet 22 and is used as hydrogenolysis reaction gas. Hydrogenolysis oil is discharged from liquid outlet 28 at the bottom of hydrogenolysis reactor and liquid product is sent to distillation column 9 by liquid transfer pump 8 for distillation to separate liquid components, and finally obtain light components, heavy components and water.

[0046] This invention also provides a method for catalytic hydrogenolysis of polylactic acid-based waste plastics, comprising the following steps:

[0047] Step 1: After PLA-based waste plastics are crushed and screened by crusher 1, they are fed into the hydrogenolysis reactor through solid feed port 21, and reaction gas H2 is introduced into the reverse hydrogenolysis reactor through gas feed port 22. The heating jacket 27 is heated by electric heating using temperature and pressure control device 26, and the stirring device 24 is turned on at the same time. The PLA-based waste plastics are melted and liquefied in the hydrogenolysis reactor. The molten and liquefied PLA-based waste plastics undergo hydrogenolysis under the action of hydrogenolysis catalyst and H2, which breaks the ester bonds of the unsaturated PLA-based waste plastic macromolecules to generate saturated small molecule lactic acid and lactic acid-like active C3 intermediates. Subsequently, the saturated small molecule lactic acid and active C3 intermediates undergo catalytic hydrogenation and reconstruction reactions to generate hydrogenolysis oils such as butyl propionate and hexyl propionate, hydrogenolysis gas such as CO, and H2O. The hydrogenolysis gas and the remaining H2 from the hydrogenolysis reaction form a gas mixture.

[0048] The hydrogenolysis reaction temperature is 250℃~300℃, the hydrogenolysis reaction pressure is 1 MPa~6 MPa, and the hydrogenolysis reaction time is 2 hours~12 hours; the stirring rate during the hydrogenolysis reaction is 1000 r / min~5000 r / min.

[0049] To improve the yield and quality of the hydrogenolysis reaction, a hydrogenolysis catalyst was selected for the reaction. The catalyst was a metal-supported catalyst with Nb₂O₅ as the support and Pt as the loaded metal, with a Pt loading of 1-10%. The hydrogenolysis catalyst was pre-loaded into a catalyst fixed bed 25.

[0050] In this step, there are no special restrictions on the source of PLA-based waste plastics; they can come from industrial production or from daily life.

[0051] Step 2: The gas mixture is transported to the pressure reducer 3 through the gas phase outlet 23 and pipeline for depressurization, reducing the pressure to 1~3 MPa to prevent excessive pressure from damaging the device; the depressurized gas mixture is sent to the drying tank 4 for drying to prevent it from affecting subsequent separation; the dried gas mixture is sent to the cold box 5, where hydrogen decomposition gas and H2 are separated by cryogenic separation method, and the separated H2 is stored in the hydrogen storage tank 6. The stored H2 can continue to participate in the hydrogen decomposition reaction as a reactant after being compressed by the compressor 7; the separated hydrogen decomposition gas can be used as fuel.

[0052] Step 3: Hydrogenated oil and H2O are pumped into distillation column 9 through liquid phase outlet 28 and liquid phase transfer pump 8. By controlling the distillation temperature, the light component and the heavy component are separated based on the boiling point difference to obtain water, other unknown carbon-containing compounds, light component hexyl propionate and heavy component butyl propionate.

[0053] The boiling point of the light component is ≤75 ℃, and the boiling point of the heavy component is >140 ℃. This invention does not impose special limitations on the distillation conditions; conventional distillation operations can be followed.

[0054] In one possible implementation, the mass percentage of PLA in the PLA-based waste plastic raw material in step 1 is 90%.

[0055] In one possible implementation, in step 1, the PLA-based waste plastic is crushed, and the particle size of the crushed PLA-based waste plastic is less than 50 mm, so as to ensure continuous and stable conveying of the crushed PLA-based waste plastic.

[0056] In one possible implementation, in step 1, the mass percentage of Pt in the hydrogenolysis catalyst is 1% to 10%.

[0057] In one possible implementation, in step 1, the mass ratio of PLA-based waste plastic to hydrogenolysis catalyst is (1~10):1.

[0058] This method not only enhances the economic efficiency of PLA-based waste plastic resource utilization, but also ensures the uniformity and reliability of the final product quality due to its simple system operation and stable operating conditions.

[0059] Example 1

[0060] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0061] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0062] The aforementioned pulverized PLA-based waste plastic is transported from the outlet of pulverizer 1 to the hydrogenolysis reactor via pipeline and solid feed inlet 21 at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 3% by mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0063] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reactor was reacted for 6 hours at 275 °C, 3 MPa H2 pressure, and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0064] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0065] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0066] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0067] Example 2

[0068] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0069] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0070] The PLA-based waste plastic, after being pulverized, is fed from the outlet of the pulverizer 1 through a pipeline and a solid feed inlet 21 to the hydrogenolysis reactor at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 3% of the total mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0071] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reactor was reacted for 6 hours at 300 °C, 3 MPa H2 pressure, and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0072] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0073] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0074] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0075] Example 3

[0076] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0077] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0078] The PLA-based waste plastic, after being pulverized, is transported from the outlet of the pulverizer 1 to the hydrogenolysis reactor via a pipeline and a solid feed inlet 21 at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 3% of the total mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0079] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reactor was reacted for 6 hours at 250 °C, 3 MPa H2 pressure, and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0080] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0081] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0082] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0083] Example 4

[0084] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0085] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0086] The PLA-based waste plastic, after being pulverized, is transported from the outlet of the pulverizer 1 to the hydrogenolysis reactor via a pipeline and a solid feed inlet 21 at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 3% of the total mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0087] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reaction was carried out for 6 hours at 275 °C, 1 MPa H2 pressure, and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0088] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0089] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0090] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0091] Example 5

[0092] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0093] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0094] The PLA-based waste plastic, after being pulverized, is transported from the outlet of the pulverizer 1 to the hydrogenolysis reactor via a pipeline and a solid feed inlet 21 at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 3% of the total mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0095] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reactor was reacted for 6 hours at 275°C, 6 MPa H2 pressure, and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0096] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0097] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0098] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0099] Example 6

[0100] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0101] Step 1: The PLA-based waste plastic from a landfill was crushed. The particle size of the crushed PLA-based waste plastic was less than 50 mm, and the mass percentage of PLA was 90%.

[0102] The PLA-based waste plastic, after being pulverized, is transported from the outlet of the pulverizer 1 to the hydrogenolysis reactor via a pipeline and a solid feed inlet 21 at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 3% of the total mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0103] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside the reverse hydrogenolysis reactor. Then, reaction gas H2 was introduced into the reverse hydrogenolysis reactor, and the temperature and pressure control device 26 was turned on. The reaction was carried out for 2 hours at 275℃, 3 MPa H2 pressure, and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0104] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0105] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0106] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0107] Example 7

[0108] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0109] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0110] The PLA-based waste plastic, after being pulverized, is transported from the outlet of the pulverizer 1 to the hydrogenolysis reactor via a pipeline and a solid feed inlet 21 at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 3% of the total mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0111] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reactor was reacted for 4 hours at 275°C, 3 MPa H2 pressure, and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0112] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0113] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0114] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0115] Example 8

[0116] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0117] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0118] The PLA-based waste plastic, after being pulverized, is transported from the outlet of the pulverizer 1 to the hydrogenolysis reactor via a pipeline and a solid feed inlet 21 at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 3% of the total mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0119] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reactor was reacted for 12 hours at 275°C, 6 MPa H2 pressure and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0120] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0121] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0122] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0123] Example 9

[0124] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0125] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0126] The pulverized PLA-based waste plastics are transported from the outlet of the pulverizer 1 to the hydrogenolysis reactor via a pipeline and a solid feed inlet 21 at a mass ratio of 5:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb2O5 catalyst, with Pt accounting for 3% of the mass, and is pre-filled in the catalyst fixed bed 25 inside the hydrogenolysis reactor.

[0127] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reactor was reacted for 6 hours at 275°C, 3 MPa H2 pressure, and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0128] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0129] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0130] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0131] Example 10

[0132] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0133] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0134] The pulverized PLA-based waste plastic is transported from the outlet of the pulverizer 1 to the hydrogenolysis reactor via a pipeline and a solid feed inlet 21 at a mass ratio of 1:1 with the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 3% of the total mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0135] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reactor was reacted for 6 hours at 275°C, 6 MPa H2 pressure, and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0136] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0137] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0138] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0139] Example 11

[0140] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0141] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0142] The aforementioned pulverized PLA-based waste plastic is transported from the outlet of the pulverizer 1 to the hydrogenolysis reactor via a pipeline and a solid feed inlet 21 at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 1% of the total mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0143] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reactor was reacted for 6 hours at 275°C, 6 MPa H2 pressure, and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0144] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0145] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0146] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0147] Example 12

[0148] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0149] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0150] The aforementioned pulverized PLA-based waste plastic is transported from the outlet of the pulverizer 1 to the hydrogenolysis reactor via a pipeline and a solid feed inlet 21 at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 10% of the total mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0151] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reactor was reacted for 6 hours at 275°C, 6 MPa H2 pressure, and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0152] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0153] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0154] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0155] Example 13

[0156] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0157] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0158] The aforementioned pulverized PLA-based waste plastic is transported from the outlet of pulverizer 1 to the hydrogenolysis reactor via pipeline and solid feed inlet 21 at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 3% by mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0159] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reactor was reacted for 6 hours at 275°C, 6 MPa H2 pressure, and 1000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0160] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0161] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0162] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0163] Example 14

[0164] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0165] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0166] The aforementioned pulverized PLA-based waste plastic is transported from the outlet of pulverizer 1 to the hydrogenolysis reactor via pipeline and solid feed inlet 21 at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 3% by mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0167] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside the reverse hydrogenolysis reactor. Then, reaction gas H2 was introduced into the reverse hydrogenolysis reactor, and the temperature and pressure control device 26 was turned on. The reaction was carried out for 6 hours at 275°C, 6 MPa H2 pressure, and 5000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0168] Step 2: The above gas mixture is first depressurized to 2 MPa by pressure reducer 3, and then the gas mixture at 2 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0169] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0170] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0171] Example 15

[0172] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0173] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0174] The PLA-based waste plastic, after being pulverized, is transported from the outlet of the pulverizer 1 to the hydrogenolysis reactor via a pipeline and a solid feed inlet 21 at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 5% by mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0175] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reactor was reacted for 6 hours at 275°C, 6 MPa H2 pressure, and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0176] Step 2: The above gas mixture is first depressurized to 1 MPa by pressure reducer 3, and then the gas mixture at 1 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0177] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0178] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0179] Example 16

[0180] exist Figure 1 The PLA-based waste plastic hydrogenolysis system shown in the figure undergoes a hydrogenolysis reaction on PLA-based waste plastics. The specific process is as follows:

[0181] Step 1: The PLA-based waste plastics from a landfill were crushed. The particle size of the crushed PLA-based waste plastics was less than 50 mm, and the mass percentage of PLA was 90%.

[0182] The PLA-based waste plastic, after being pulverized, is transported from the outlet of the pulverizer 1 to the hydrogenolysis reactor via a pipeline and a solid feed inlet 21 at a mass ratio of 10:1 to the hydrogenolysis catalyst. The hydrogenolysis catalyst is a Pt / Nb₂O₅ catalyst, with Pt accounting for 3% of the total mass, and is pre-filled in the catalyst fixed bed 25 within the hydrogenolysis reactor.

[0183] Ar gas was introduced into the hydrogenolysis reactor to purge the reactor and remove the air inside. Then, H2 was introduced into the reactor and the temperature and pressure control device 26 was turned on. The reactor was reacted for 6 hours at 275°C, 6 MPa H2 pressure, and 3000 r / min stirring speed of the stirring device 24. Finally, a gas mixture, hydrogenolysis oil and water were obtained.

[0184] Step 2: The above gas mixture is first depressurized to 3 MPa by pressure reducer 3, and then the gas mixture at 3 MPa is dried by drying tank 4 and sent to cold box 5 at -100 ℃ for cryogenic separation to separate H2 and hydrogen decomposition gas. The separated H2 is sent to hydrogen storage tank 6 for storage for subsequent use.

[0185] Step 3: The above-mentioned hydrolyzed oil is sent to the distillation column 9 by liquid phase transfer pump 8 for distillation to obtain water, hexyl propionate, butyl propionate and other unknown carbon-containing compounds, wherein hexyl propionate is a light component and butyl propionate is a heavy component with a high boiling point.

[0186] The mass of the liquid was obtained by weighing, and the mass of the gaseous product was obtained by subtraction. The product yield was calculated based on the mass of each product. The yields of hydrogenolysis gas, hexyl propionate, butyl propionate, and water obtained in this example are shown in Table 1.

[0187] Table 1

[0188]

[0189] The formula for calculating the conversion rate in Table 1 is as follows:

[0190] ;

[0191] After treatment by the catalytic hydrogenolysis method provided by this invention, the conversion rate of PLA-based waste plastics is as high as 100%, the yield of butyl propionate is 56.8%, and the yield of hexyl propionate is 10.5%. Moreover, the boiling points of the above products are quite different, making them easy to separate by distillation.

[0192] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polylactic acid-based waste plastic catalytic hydrogenolysis system, characterized in that, It includes a crusher (1), a hydrogenolysis reactor, a pressure reducer (3), a liquid phase transfer pump (8), a hydrogen separation system, and a distillation column (9); The outlet of the pulverizer (1) is connected to the solid feed inlet (21) of the hydrogenolysis reactor; The hydrogenolysis reactor includes a reactor body, a stirring device (24), a catalyst fixed bed (25), a temperature and pressure control device (26), and a heating jacket (27). The stirring blades of the catalyst fixed bed (25) and the stirring device (24) are located inside the reactor body, and the heating jacket (27) covers the reactor body. The temperature and pressure control device (26) and the heating jacket (27) are electrically connected. The catalyst fixed bed (25) is filled with a hydrogenolysis catalyst, which is a Pt supported catalyst with Nb2O5 as the support. The vessel body is provided with a solid phase inlet (21), a gas phase inlet (22), a gas phase outlet (23) and a liquid phase outlet (28). The gas phase outlet (23) is connected to the inlet of the pressure reducer (3), the outlet of the pressure reducer (3) is connected to the inlet of the hydrogen separation system, and the outlet of the hydrogen separation system is connected to the gas phase inlet (22). The liquid outlet (28) is connected to the inlet of the distillation column (9).

2. The polylactic acid-based waste plastic catalytic hydrogenolysis system according to claim 1, characterized in that, The hydrogen separation system includes a drying tank (4), a cold box (5), a hydrogen storage tank (6), and a compressor (7). The inlet of the drying tank (4) is connected to the outlet of the pressure reducer (3), and the outlet of the drying tank (4) is connected to the inlet of the cold box (5). The outlet of the cold box (5) is connected to the inlet of the hydrogen storage tank (6), and the outlet of the hydrogen storage tank (6) is connected to the inlet of the compressor (7). The outlet of the compressor (7) is connected to the gas phase feed port (22).

3. The polylactic acid-based waste plastic catalytic hydrogenolysis system according to claim 1, characterized in that, The rotation trajectory of the stirring blades of the stirring device (24) is tangent to the inner surface of the catalyst fixed bed (25).

4. A method for catalytic hydrogenolysis of polylactic acid-based waste plastics, based on the polylactic acid-based waste plastics catalytic hydrogenolysis system according to any one of claims 1 to 3, characterized in that, Includes the following steps: Step 1: After the polylactic acid-based waste plastic is crushed and screened by a crusher (1), it is fed into a hydrogenolysis reactor. H2 is introduced into the hydrogenolysis reactor. The polylactic acid-based waste plastic is heated and melted in the hydrogenolysis reactor. The molten polylactic acid macromolecules undergo hydrogenolysis under the action of hydrogenolysis catalyst and H2, which breaks the ester bonds of unsaturated polylactic acid macromolecules and generates saturated small molecule lactic acid and active C3 intermediate. Subsequently, the saturated small molecule lactic acid and active C3 intermediate generate hydrogenolysis oil, hydrogenolysis gas and H2O through catalytic hydrogenation and reconstruction reaction. The hydrogenolysis catalyst is a Pt supported catalyst and the support is Nb2O5. Step 2: After depressurizing and drying the hydrogenolysis gas and the remaining H2 from the hydrogenolysis reaction, send them into a cold box (5) to separate the hydrogenolysis gas and H2 by cryogenic separation method; The mixture of hydrogenated oil and water was subjected to component separation to obtain water, hexyl propionate and butyl propionate; In step 1, the conditions for the hydrogenolysis reaction include: a hydrogenolysis reaction temperature of 250℃~300℃, a hydrogenolysis reaction pressure of 1MPa~6MPa, and a hydrogenolysis reaction time of 2 hours~12 hours. In step 2, the mixture of hydrogenated oil and water is separated by distillation. During distillation, the boiling point of the light component is ≤75 ℃, and the boiling point of the heavy component is >140 ℃.

5. The method for catalytic hydrogenolysis of polylactic acid-based waste plastics according to claim 4, characterized in that, In step 1, the mass ratio of polylactic acid-based waste plastic to hydrogenolysis catalyst is (1~10):

1.

6. The method for catalytic hydrogenolysis of polylactic acid-based waste plastics according to claim 4, characterized in that, In step 1, the mass percentage of Pt in the hydrogenolysis catalyst is 1% to 10%.

7. The method for catalytic hydrogenolysis of polylactic acid-based waste plastics according to claim 4, characterized in that, In step 1, during the hydrogenolysis reaction, the stirring rate of the stirring device (24) is 1000 r / min ~ 3000 r / min.

8. The method for catalytic hydrogenolysis of polylactic acid-based waste plastics according to claim 4, characterized in that, In step 2, after separating the hydrogen decomposition gas and H2, the separated H2 is sent to the hydrogen storage tank (6) for storage. The stored H2 is compressed by the compressor (7) and used as the reaction gas for the hydrogen decomposition reaction.

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