Microwave-driven pyrolysis system and method for preparing high-octane gasoline from waste polypropylene plastic

Abstract

The invention provides a microwave-driven pyrolysis system and a microwave-driven pyrolysis method for preparing high-octane gasoline from waste polypropylene plastics, and belongs to the technical field of recycling of polymer wastes. The invention aims to solve the problems of complex product components and low resource utilization rate in traditional cracking. The left side of a microwave pyrolyzing furnace is connected with a nitrogen cylinder, the right side of the microwave pyrolyzing furnace is connected with a gas collecting cylinder through a condenser, and silicon carbide is placed in the microwave pyrolyzing furnace; the top of the microwave pyrolyzing furnace is provided with a feeder, the bottom is provided with a stirrer, and the side wall is provided with a magnetron and a thermocouple. According to the invention, silicon carbide (used as a wave absorbing agent) and waste polypropylene are uniformly mixed, so that microwave-driven overall heating is realized, microwave energy can be efficiently utilized, side reactions are inhibited, polypropylene cracking products are concentrated in a gasoline hydrocarbon range, high-octane gasoline can be directly generated, low-value components and coke are reduced, and the production cost is reduced. High-value products can be obtained without deep refining, and the accuracy and economical efficiency of resource conversion are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer waste resource utilization, and in particular relates to a microwave-driven pyrolysis system and method for preparing high-octane gasoline from waste polypropylene plastics. Background Art

[0002] Under the "dual carbon" strategy, achieving high-value resource utilization for waste polypropylene is crucial for reducing primary resource consumption and lowering carbon emissions. my country produces over 10 million tons of waste polypropylene annually, and its disposal faces severe challenges: traditional landfilling occupies land and pollutes the environment, while incineration produces large amounts of carbon dioxide.

[0003] While thermal cracking technology can convert waste polypropylene into fuel oil, its core limitation lies in the extremely complex product composition and significantly insufficient added value. Conventional thermal cracking processes produce numerous side reactions, resulting in a complex composition of the pyrolysis oil. This composition includes a large amount of low-value waxes, heavy tars, and harmful aromatics, while high-octane components (such as isoparaffins and olefins) are low in proportion, with octane numbers (RON) generally below 80. Furthermore, non-selective cracking is associated with high coke yields, further reducing resource utilization and generating solid waste.

[0004] Therefore, it is urgent to design a method that can solve the problems of complex product composition and low resource utilization in traditional cracking, realize the targeted regulation of product composition, directly generate a high proportion of high-octane gasoline components (RON>90) without deep refining, improve resource utilization and environmental protection, and further meet the "dual carbon" strategy and industry needs. Summary of the Invention

[0005] A brief overview of the present invention is provided below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify key or important aspects of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is simply to present certain concepts in a simplified form as a prelude to the more detailed description discussed later.

[0006] In view of this, in order to solve the problems of complex product composition and low resource utilization in traditional cracking, the present invention provides a microwave-driven pyrolysis system and method for preparing high-octane gasoline from waste polypropylene plastics.

[0007] Solution 1: A microwave-driven pyrolysis system for producing high-octane gasoline from waste polypropylene plastics, including a nitrogen bottle, a magnetron, a feeder, an agitator, a microwave pyrolysis furnace, silicon carbide, a thermocouple, a condenser, and a gas collecting bottle;

[0008] The left side of the microwave pyrolysis furnace is connected to a nitrogen bottle, and the right side is connected to a gas collecting bottle through a condenser. The silicon carbide is placed in the microwave pyrolysis furnace;

[0009] The microwave pyrolysis furnace is provided with a feeder on the top, a stirrer on the bottom, and a magnetron and a thermocouple on the side wall.

[0010] Furthermore, the silicon carbide is black silicon carbide with a purity of more than 98% and a particle size of 1-5 mm.

[0011] Furthermore, the magnetron is provided with a microwave generating module with a frequency of 2.45 GHz, which can output microwaves of 2.45 GHz with variable power.

[0012] Solution 2: A microwave-driven pyrolysis method for producing high-octane gasoline from waste polypropylene plastics, which is implemented based on the microwave-driven pyrolysis system for producing high-octane gasoline from waste polypropylene plastics described in Solution 1, and specifically includes the following steps:

[0013] S1. Mechanically cut the waste polypropylene products into pieces with an area of ​​3*3-12*12mm 2 The fragments are fed into the microwave pyrolysis furnace through a feeder;

[0014] S2. After the feeding is completed, the feed port is closed and the stirrer is turned on to mix the polypropylene fragments and silicon carbide in a mass ratio of 1:2-1:5;

[0015] S3. Open the nitrogen cylinder to exhaust the air in the system, then close the nitrogen cylinder;

[0016] S4. Turn on the magnetron to transmit microwaves and set the microwave power according to the standard of 5-10W / g silicon carbide;

[0017] S5. The pyrolysis temperature was set within a range of 350-420°C. After the microwave pyrolysis system was turned on, the polypropylene temperature was rapidly raised to the pyrolysis temperature. The temperature was maintained within ±10°C of the pyrolysis temperature by switching the magnetron on and off. The temperature was measured using a thermocouple.

[0018] S6. The pyrolysis oil and pyrolysis gas produced by the microwave pyrolysis system are collected in a condenser and a gas collecting bottle, respectively. The pyrolysis oil is distilled and separated to obtain high-octane gasoline.

[0019] Furthermore, the waste polypropylene products are any polypropylene products, including plastic bottles, packaging bags and disposable tableware.

[0020] Furthermore, the pyrolysis oil yield is 72-85wt%, the olefin content in the pyrolysis oil is 30%-50%, the cycloalkane content is 40%-60%, the alkane content is 2%-10%, the cycloolefin content is 1%-6%, the aromatic hydrocarbon content is <2%, and the gasoline hydrocarbon content is 92%-97%. The octane number of the gasoline obtained by distillation separation is 90-94.

[0021] The present invention has the following beneficial effects compared to the prior art:

[0022] 1. This invention achieves microwave-driven overall heating by uniformly mixing silicon carbide (as a microwave absorber) and waste polypropylene. This efficiently utilizes microwave energy and suppresses side reactions, concentrating the polypropylene cracking products within the gasoline hydrocarbon range. This allows for the direct production of high-octane gasoline, while reducing the production of low-value components (such as linear alkanes and heavy tar) and coke. High-value products can be obtained without extensive refining, significantly improving the accuracy and cost-effectiveness of resource conversion.

[0023] 2. This invention converts waste plastics into high-octane gasoline, which not only solves the problem of waste plastic disposal, but also provides a supplementary path for energy supply, helping to optimize the energy structure. At the same time, this technical model promotes the closed-loop cycle of "waste-resource-energy", providing practical support for the development of the circular economy and energy transformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0025] Figure 1 Schematic diagram of the structure of a microwave-driven pyrolysis system for producing high-octane gasoline from waste polypropylene plastic.

[0026] In the figure: 1-nitrogen bottle, 2-magnetron, 3-feeder, 4-stirrer, 5-microwave pyrolysis furnace, 6-silicon carbide, 7-thermocouple, 8-condenser, 9-gas collecting bottle. DETAILED DESCRIPTION

[0027] To make the technical solutions and advantages of the embodiments of the present invention more clearly understood, exemplary embodiments of the present invention are further described in detail below with reference to the accompanying drawings. It should be noted that the embodiments described are only a portion of the embodiments of the present invention, and are not an exhaustive list of all embodiments. It should be noted that the embodiments of the present invention and the features thereof may be combined with each other unless they conflict.

[0028] Example 1, reference Figure 1 To illustrate this embodiment, a microwave-driven pyrolysis system for preparing high-octane gasoline from waste polypropylene plastics includes a nitrogen cylinder 1, a magnetron 2, a feeder 3, an agitator 4, a microwave pyrolysis furnace 5, silicon carbide 6, a thermocouple 7, a condenser 8, and a gas collecting bottle 9;

[0029] The left side of the microwave pyrolysis furnace 5 is connected to the nitrogen bottle 1, and the right side is connected to the gas collecting bottle 9 through the condenser 8. The silicon carbide 6 is placed in the microwave pyrolysis furnace 5;

[0030] The microwave pyrolysis furnace 5 is provided with a feeder 3 on the top, a stirrer 4 on the bottom, and a magnetron 2 and a thermocouple 7 on the side wall.

[0031] Furthermore, the silicon carbide 6 is black silicon carbide with a purity of more than 98% and a particle size of 1-5 mm.

[0032] Furthermore, the magnetron 2 is provided with a microwave generating module with a frequency of 2.45 GHz, which can output microwaves of 2.45 GHz with variable power.

[0033] Example 2, reference Figure 1 This embodiment describes a microwave-driven pyrolysis method for producing high-octane gasoline from waste polypropylene plastics. The method is implemented based on the microwave-driven pyrolysis system for producing high-octane gasoline from waste polypropylene plastics described in Example 1, and specifically includes the following steps:

[0034] S1. Mechanically cut the waste polypropylene products into pieces with an area of ​​3*3-12*12mm 2 The fragments are fed into the microwave pyrolysis furnace 5 via the feeder 3;

[0035] S2. After the feeding is completed, the feed port is closed and the stirrer 4 is turned on so that the polypropylene fragments and the silicon carbide 6 are mixed uniformly in a mass ratio of 1:2-1:5;

[0036] S3. Open the nitrogen cylinder 1 to exhaust the air in the system, and then close the nitrogen cylinder 1;

[0037] S4. Turn on the magnetron 2 to transmit microwaves and set the microwave power according to the standard of 5-10W / g silicon carbide 6;

[0038] S5. The pyrolysis temperature setting range is 350-420 ° C. After the microwave pyrolysis system is turned on, the polypropylene is rapidly heated to the pyrolysis temperature. The temperature is maintained within ± 10 ° C of the pyrolysis temperature by "on-off" the magnetron 2. The temperature is measured by the thermocouple 7;

[0039] S6. The pyrolysis oil and pyrolysis gas generated by the microwave pyrolysis system are collected in the condenser 8 and the gas collecting bottle 9 respectively, and the pyrolysis oil is separated by distillation to obtain high-octane gasoline.

[0040] Furthermore, the waste polypropylene products are any polypropylene products, including plastic bottles, packaging bags and disposable tableware.

[0041] Furthermore, the pyrolysis oil yield is 72-85wt%, the olefin content in the pyrolysis oil is 30%-50%, the cycloalkane content is 40%-60%, the alkane content is 2%-10%, the cycloolefin content is 1%-6%, the aromatic hydrocarbon content is <2%, and the gasoline hydrocarbon content is 92%-97%. The octane number of the gasoline obtained by distillation separation is 90-94.

[0042] Example 3, reference Figure 1 To illustrate this embodiment, a microwave-driven pyrolysis system for producing high-octane gasoline using waste polypropylene plastic was used for experiments;

[0043] First, 20 g of waste polypropylene fragments were evenly mixed with 50 g of silicon carbide 6, the microwave power was set to 450 W, and the pyrolysis temperature was set to 360 ° C;

[0044] Secondly, microwave is turned on and polypropylene is rapidly heated to 360℃. The temperature of polypropylene is controlled to be maintained within 360±10℃ by switching magnetron 2.

[0045] Finally, 16.71 g of pyrolysis oil was collected in the condenser 8. The olefin content, cycloalkane content, alkane content, and cycloalkene content of the pyrolysis oil were 44.22%, 49.44%, 5.19%, and 1.16%, respectively. The pyrolysis oil contained no aromatic hydrocarbons and had a gasoline hydrocarbon content of 95.37%. The octane number of the gasoline obtained by distillation separation was 93.07.

[0046] Example 4, reference Figure 1 To illustrate this embodiment, a microwave-driven pyrolysis system for producing high-octane gasoline using waste polypropylene plastic was used for experiments;

[0047] First, 10 g of waste polypropylene fragments were evenly mixed with 50 g of silicon carbide 6, the microwave power was set to 450 W, and the pyrolysis temperature was set to 390 °C;

[0048] Secondly, microwave is turned on and polypropylene is rapidly heated to 390℃. The temperature of polypropylene is controlled to be maintained within 390±10℃ by switching magnetron 2.

[0049] Finally, 7.873 g of pyrolysis oil was collected in condenser 8. The pyrolysis oil contained 47.82% olefins, 46.44% cycloalkanes, 3.11% alkanes, 2.63% cycloalkenes, no aromatics, and a gasoline hydrocarbon content of 96.74%. The gasoline octane number obtained by distillation was 93.58.

[0050] Example 5, reference Figure 1 To illustrate this embodiment, a microwave-driven pyrolysis system for producing high-octane gasoline using waste polypropylene plastic was used for experiments;

[0051] First, 20 g of waste polypropylene fragments were evenly mixed with 70 g of silicon carbide 6, the microwave power was set to 450 W, and the pyrolysis temperature was set to 360 ° C;

[0052] Then the microwave is turned on and the polypropylene is quickly heated to 360°C. The temperature of the polypropylene is controlled to be maintained within 360±10°C by switching the magnetron 2;

[0053] Finally, 16.46 g of pyrolysis oil was collected in the condenser 8. The olefin content of the pyrolysis oil was 36.57%, the cycloalkane content was 55.44%, the alkane content was 6.1%, the cycloolefin content was 1.89%, there was no aromatic hydrocarbon, and the gasoline hydrocarbon content was 95.5%. The octane number of the gasoline obtained by distillation separation was 91.37.

[0054] Example 6, reference Figure 1 To illustrate this embodiment, a microwave-driven pyrolysis system for producing high-octane gasoline using waste polypropylene plastic was used for experiments;

[0055] First, 100 g of waste polypropylene fragments were evenly mixed with 400 g of silicon carbide 6, the microwave power was set to 2000 W, and the pyrolysis temperature was set to 360 ° C;

[0056] Then the microwave is turned on and the polypropylene is quickly heated to 360°C. The temperature of the polypropylene is controlled to be maintained within 360±10°C by switching the magnetron 2;

[0057] Finally, 81.83 g of pyrolysis oil was collected in the condenser 8. The pyrolysis oil contained 33% olefins, 59.73% cycloalkanes, 5.93% alkanes, 1.33% cycloalkenes, 0.01% aromatics, and 94.42% gasoline hydrocarbons. The octane number of the gasoline obtained by distillation separation was 91.37.

[0058] By uniformly mixing silicon carbide (as an absorber) and waste polypropylene in the present invention, microwave-driven overall heating is achieved, which can efficiently utilize microwave energy and suppress side reactions, so that the polypropylene cracking products are concentrated within the gasoline hydrocarbon range, and high-octane gasoline can be directly generated, while the production of low-value components (such as straight-chain alkanes and heavy tar) and coke is reduced. High-value products can be obtained without deep refining, which significantly improves the accuracy and economy of resource conversion.

[0059] The present invention converts waste plastics into high-octane gasoline, which not only solves the problem of waste plastic disposal, but also provides a supplementary path for energy supply, which helps to optimize the energy structure; at the same time, this technical model promotes the closed-loop cycle of "waste-resources-energy", and provides practical support for the development of circular economy and energy transformation.

[0060] Although the present invention has been described with respect to a limited number of embodiments, it will be apparent to those skilled in the art, having benefit of the foregoing description, that other embodiments are contemplated within the scope of the invention thus described. Furthermore, it should be noted that the language used in this specification has been selected primarily for readability and didactic purposes, rather than for the purpose of explaining or limiting the subject matter of the present invention. Consequently, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is intended to be illustrative rather than restrictive of the scope of the invention, which is defined by the appended claims.

Claims

1. A microwave-driven pyrolysis system for producing high-octane gasoline from waste polypropylene plastics, characterized in that: It includes a nitrogen bottle (1), a magnetron (2), a feeder (3), a stirrer (4), a microwave pyrolysis furnace (5), silicon carbide (6), a thermocouple (7), a condenser (8) and a gas collecting bottle (9); The left side of the microwave pyrolysis furnace (5) is connected to the nitrogen bottle (1), and the right side is connected to the gas collecting bottle (9) through the condenser (8). The silicon carbide (6) is placed in the microwave pyrolysis furnace (5); The microwave pyrolysis furnace (5) is provided with a feeder (3) on the top, a stirrer (4) on the bottom, and a magnetron (2) and a thermocouple (7) on the side wall.

2. The microwave-driven pyrolysis system for preparing high-octane gasoline from waste polypropylene plastics according to claim 1, characterized in that: The silicon carbide (6) is black silicon carbide with a purity of more than 98% and a particle size of 1-5 mm.

3. The microwave-driven pyrolysis system for preparing high-octane gasoline from waste polypropylene plastics according to claim 1, characterized in that: The magnetron (2) is provided with a microwave generating module with a frequency of 2.45 GHz, which can output microwaves of 2.45 GHz with variable power.

4. A microwave-driven pyrolysis method for producing high-octane gasoline from waste polypropylene plastics, which is implemented by using the microwave-driven pyrolysis system for producing high-octane gasoline from waste polypropylene plastics according to claim 1, characterized in that: The specific steps include: S1. Mechanically cut the waste polypropylene products into pieces with an area of ​​3*3-12*12mm 2 The fragments are fed into the microwave pyrolysis furnace (5) via the feeder (3); S2. After the feeding is completed, the feed port is closed and the stirrer (4) is turned on to mix the polypropylene fragments and the silicon carbide (6) in a mass ratio of 1:2-1:5; S3. Open the nitrogen bottle (1) to exhaust the air in the system, and then close the nitrogen bottle (1); S4. Turn on the magnetron (2) to emit microwaves and set the microwave power according to the standard of 5-10 W / g silicon carbide (6); S5. The pyrolysis temperature setting range is 350-420°C. After the microwave pyrolysis system is turned on, the temperature of polypropylene is rapidly raised to the pyrolysis temperature. The temperature is maintained within ±10°C of the pyrolysis temperature by "on-off" the magnetron (2). The temperature is measured by a thermocouple (7); S6. The pyrolysis oil and pyrolysis gas generated by the microwave pyrolysis system are collected in a condenser (8) and a gas collecting bottle (9) respectively, and the pyrolysis oil is separated by distillation to obtain high-octane gasoline.

5. The microwave-driven pyrolysis method for preparing high-octane gasoline from waste polypropylene plastics according to claim 4, characterized in that: The pyrolysis oil yield is 72-85wt%, the olefin content in the pyrolysis oil is 30%-50%, the cycloalkane content is 40%-60%, the alkane content is 2%-10%, the cycloalkene content is 1%-6%, the aromatic hydrocarbon content is less than 2%, and the gasoline hydrocarbon content is 92%-97%. The octane number of the gasoline obtained by distillation separation is 90-94.

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