A method and system for catalytic cracking of waste plastics

Abstract

The present invention relates to the technical field of waste plastic recycling, and particularly relates to a method and a system for catalytic cracking of waste plastics. The system for catalytic cracking of waste plastics includes: a reactor; a raw material feed port is arranged at the bottom of the reactor; a catalyst feed port and a gas-solid separation device are arranged at the top of the reactor; a preheating furnace connected to the raw material feed port of the reactor; a vaporization furnace connected to the inlet of the preheating furnace through a first pipeline; a raw material tank connected to the first pipeline at the inlet of the preheating furnace through a second pipeline; an air supply device; the air supply device is connected to the preheating furnace; a primary condensation device connected to the gas outlet of the gas-solid separation device; a liquid collection device connected to the outlet of the primary condensation device. The system for catalytic cracking of waste plastics of the present invention does not need to use a decontamination unit, a plurality of catalyst coolers and a deactivated catalyst regenerator, and does not need to add a dechlorinating agent, and obtains a relatively high light fuel oil yield.

Description

Technical Field

[0001] The present invention relates to the technical field of waste plastic recycling, and particularly relates to a method and a system for catalytic cracking of waste plastics. Background Art

[0002] With the increasing consumption of global fossil energy, the problem of carbon energy recycling has gradually attracted wide attention. In recent years, a large amount of plastic products are produced globally every year. The produced plastic products cause serious environmental pollution due to their short use cycle and long lifespan. In the past half century, the global plastic production has increased by 20 times, and it is expected that the growth trend will continue, and the annual plastic production will exceed 500 million tons by 2050. Currently, there are more than 30 primary plastics, which can form different varieties of plastic materials after being combined with different additives. The main plastic-producing country in the world is China, accounting for 27.8% of the global plastic production, followed by the European Union and North America, accounting for 18.5% of the global plastic production.

[0003] To solve the "white pollution" problem caused by plastic waste, the current main treatment methods are landfill and incineration. Since plastics are light in weight, large in volume and difficult to degrade, the landfill method will occupy a large amount of land resources and harm the ecological environment; while the incineration method will produce a large amount of toxic and harmful gases and there are serious carbon emission problems. Thus, it can be seen that the current main waste plastic treatment methods will all cause serious secondary pollution and result in the waste of waste plastic resources.

[0004] To achieve the high-value utilization of waste plastics, the use of catalytic cracking technology to convert waste plastics into fuel oil and high-value-added products has broad application prospects. The patent with the publication number CN113862018A discloses a method and a system for producing vehicle fuel oil from waste plastics. The waste plastics first enter a decontamination unit for decontamination treatment to obtain a solution with low chlorine content and low silicon content; the solution with low impurity content is sent to a catalytic cracking unit for catalytic cracking reaction to prepare vehicle fuel oil. The patent with the publication number CN114106864A discloses a method and a system for producing low-chlorine fuel oil from waste plastics. In this method, the waste plastics are first mixed and contacted with a deactivated catalyst at 150 - 300°C in a pipeline, and then further react in the upper and middle reaches of a fluidized reactor; the regenerated catalyst at 600 - 680°C and a dechlorinating agent enter the reactor from the middle and lower reaches of the reactor, contact and react with the existing logistics in the reactor; the reacted logistics finally enter a separation system. It can be seen that the above technical solutions need to adopt a decontamination unit, multiple catalyst coolers and a deactivated catalyst regenerator, and also need to add a dechlorinating agent. The reaction process is cumbersome and the investment cost is relatively high, which is not conducive to improving economic benefits.

[0005] Due to the high viscosity of waste plastics, when waste plastics come into contact with the catalyst, they are likely to cover the surface of the catalyst to form carbon deposits, making it difficult for reaction intermediates to diffuse into the active sites inside the catalyst for reaction. In addition, the poor thermal conductivity of waste plastics causes uneven heating of waste plastics during the reaction, resulting in deteriorated properties of the cracking products. The high chlorine content in waste plastics leads to a high content of organic chlorides in the cracked product fuel oil. These characteristics of waste plastics all have a serious negative impact on the cracking conversion of waste plastics and the quality of the cracking products. Therefore, it is necessary to develop an economical and efficient catalytic cracking method for waste plastics to improve the cracking conversion rate of waste plastics and the quality of the cracking products, so as to realize the high-value utilization of waste plastics. Summary of the Invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a catalytic cracking method and system for waste plastics, which is conducive to the conversion of urban waste plastics into light fuel oil and the system has simple operation.

[0007] The present invention provides a system for catalytic cracking of waste plastics, including:

[0008] A reactor; a raw material feed port is arranged at the bottom of the reactor; a catalyst feed port and a gas-solid separation device are arranged at the top of the reactor;

[0009] A preheating furnace connected to the raw material feed port of the reactor;

[0010] A vaporization furnace connected to the inlet of the preheating furnace through a first pipeline;

[0011] A raw material tank connected to the first pipeline at the inlet of the preheating furnace through a second pipeline;

[0012] An air supply device; the air supply device is connected to the preheating furnace;

[0013] A primary condensation device connected to the gas outlet of the gas-solid separation device;

[0014] A liquid collection device connected to the outlet of the primary condensation device.

[0015] Preferably, it further includes: a high-temperature heating furnace;

[0016] The reactor is placed in the high-temperature heating furnace;

[0017] The reactor includes one or more of a conical jet bed reactor, a particulate fluidized bed reactor, a dispersed fluidized bed reactor, a boiling bed reactor, a turbulent bed reactor, and a riser reactor.

[0018] Preferably, it further includes: a water storage tank and a water inlet pump;

[0019] The inlet of the water inlet pump is connected to the outlet of the water storage tank;

[0020] The outlet of the feed water pump is connected to the inlet of the vaporizer furnace.

[0021] Preferably, it further includes: a constant temperature heating device;

[0022] The raw material tank is placed in the constant temperature heating device;

[0023] and / or

[0024] It further includes: a raw material pump;

[0025] The raw material pump is used to transport the liquefied waste plastic liquid in the raw material tank to the preheating furnace and the reactor.

[0026] Preferably, it further includes: an oxygen supply device;

[0027] The air supply device is connected to the preheating furnace through a first gas flowmeter;

[0028] The oxygen supply device is connected to the preheating furnace through a second gas flowmeter.

[0029] Preferably, it further includes:

[0030] A secondary condensation device connected to the gas outlet of the liquid collection device;

[0031] A tertiary condensation device connected to the gas outlet of the secondary condensation device;

[0032] The secondary condensation device is a serpentine condenser;

[0033] The tertiary condensation device is a serpentine condenser, and the tertiary condensation device is refrigerated by a refrigeration circulation pump;

[0034] The primary condensation device is a straight condenser.

[0035] The present invention also provides a method for catalytic cracking of waste plastics by the system described above, including the following steps:

[0036] A) After loading the catalyst in the reactor, turn on the temperature increase programs of the vaporizer furnace, the preheating furnace and the high-temperature heating furnace;

[0037] B) Introduce preheated air into the reactor to fluidize the catalyst in the reactor;

[0038] C) When the temperature in the vaporizer furnace reaches 150 - 350 °C, introduce preheated steam into the reactor to fluidize the catalyst in the reactor;

[0039] D) When the temperature in the reactor reaches 400 - 600 °C, the waste plastic liquefied liquid and steam converge in the pipeline at the inlet of the preheating furnace, enter the reactor after being heated by the preheating furnace for catalytic cracking reaction, and the products after the reaction are subjected to gas-solid separation. The cracking products and steam obtained from the gas-solid separation are condensed to obtain cracked oil and condensed water.

[0040] Preferably, in step A), the set temperature of the vaporization furnace is 150 - 350 °C, the set temperature of the preheating furnace is 200 - 350 °C, and the set temperature of the reactor is 400 - 600 °C;

[0041] The flow rate of the air is 2 - 10 L / min, and the pressure of the air at the inlet of the reactor is 0.20 - 1 MPa.

[0042] Preferably, in step C), during the process of introducing preheated steam into the reactor, the rate of conveying water to the vaporization furnace is 1 - 10 g / min;

[0043] In step D), the flow rate of the waste plastic liquefied liquid conveyed from the raw material tank is 0.33 - 0.56 g / s;

[0044] The time of the catalytic cracking reaction is 80 - 120 s.

[0045] Preferably, the mass ratio of the catalyst to the waste plastic liquefied liquid is 1 - 10:1.

[0046] The present invention provides a system for catalytic cracking of waste plastics, including: a reactor; a raw material feed port is arranged at the bottom of the reactor; a catalyst feed port and a gas-solid separation device are arranged at the top of the reactor; a preheating furnace connected to the raw material feed port of the reactor; a vaporization furnace connected to the inlet of the preheating furnace through a first pipeline; a raw material tank connected to the first pipeline at the inlet of the preheating furnace through a second pipeline; an air supply device; the air supply device is connected to the preheating furnace; a primary condensation device connected to the gas outlet of the gas-solid separation device; a liquid collection device connected to the outlet of the primary condensation device. The system for catalytic cracking of waste plastics provided by the present invention does not need to use a decontamination unit, multiple catalyst coolers and a deactivated catalyst regenerator, and does not need to add a dechlorinating agent, and obtains a high light fuel oil yield. At the same time, the present invention greatly simplifies the reaction process, reduces the investment cost and improves the economic benefit.

[0047] Experimental results show that the system and method provided by the present invention are beneficial to the conversion of urban waste plastics into light fuel oil, can obtain a high light fuel oil yield, and the chlorine content in the cracked oil is greatly reduced, greatly reducing the recycling cost of urban waste plastics, and realizing the high-value utilization of inferior waste plastics. Description of the Drawings

[0048] Figure 1 System diagram of catalytic cracking of waste plastics provided for an embodiment of the present invention. Detailed implementation manners

[0049] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0050] The present invention provides a system for catalytic cracking of waste plastics, comprising:

[0051] A reactor; a raw material feed port is arranged at the bottom of the reactor; a catalyst feed port and a gas-solid separation device are arranged at the top of the reactor;

[0052] A preheating furnace connected to the raw material feed port of the reactor;

[0053] A vaporization furnace connected to the inlet of the preheating furnace through a first pipeline;

[0054] A raw material tank connected to the first pipeline at the inlet of the preheating furnace through a second pipeline;

[0055] An air supply device; the air supply device is connected to the preheating furnace;

[0056] A primary condensation device connected to the gas outlet of the gas-solid separation device;

[0057] A liquid collection device connected to the outlet of the primary condensation device.

[0058] Figure 1 System diagram of catalytic cracking of waste plastics provided for an embodiment of the present invention. Among them, 1 is an air supply device, 2 is an oxygen supply device, 3-1 is a first gas flowmeter, 3-2 is a second gas flowmeter, 4 is a water storage tank, 5 is a water inlet pump, 6 is a vaporization furnace, 7 is a preheating furnace, 8 is a raw material tank, 9 is a raw material pump, 10 is a constant temperature heating device, 11 is a high temperature heating furnace, 12 is a reactor, 13 is a catalyst feed port, 14 is a gas-solid separation device, 15 is the gas outlet of the gas-solid separation device, 16 is a primary condensation device, 17 is a liquid collection device, 18 is a secondary condensation device, 19 is a refrigeration circulation pump, 20 is a tertiary condensation device, 21 is a gas collection device, 22 is a cracked gas outlet, and 23 is a flue gas outlet.

[0059] The system for catalytic cracking of waste plastics provided by the present invention includes a feeding system, a stripping / atomization system, a gas supply system, a reaction / regeneration system, and a product separation system.

[0060] The feeding system includes: a constant-temperature heating device 10, a raw material pump 9, a raw material tank 8, and a preheating furnace 7.

[0061] The stripping water / atomization system includes: a water storage tank 4, a water inlet pump 5, and a vaporization furnace 6.

[0062] The gas supply system includes: an air supply device 1, an oxygen supply device 2, a first gas flowmeter 3-1, and a second gas flowmeter 3-2.

[0063] The reaction / regeneration system includes: a high-temperature heating furnace 11, a reactor 12, and a gas-solid separation device 14.

[0064] The product separation system includes: a primary condensation device 16, a secondary condensation device 18, a tertiary condensation device 20, a refrigeration circulation pump 19, a liquid collection device 17, and a gas collection device 21.

[0065] The waste plastic catalytic cracking system provided by the present invention includes a reactor 12. A catalyst is loaded in the reactor 12; a raw material inlet is provided at the bottom of the reactor; a catalyst inlet and a gas-solid separation device 14 are provided at the top of the reactor.

[0066] In certain embodiments of the present invention, the reactor includes one or more of a conical jet bed reactor, a bubbling fluidized bed reactor, a particulate fluidized bed reactor, a boiling bed reactor, a turbulent bed reactor, and a riser reactor. The conical jet bed reactor is a conical stainless steel tube.

[0067] In certain embodiments of the present invention, the waste plastic catalytic cracking system further includes: a high-temperature heating furnace 11; the reactor is placed in the high-temperature heating furnace to facilitate heating the reactor. The high-temperature heating furnace can be a generally commercially available jacket heating device.

[0068] In certain embodiments of the present invention, the gas-solid separation device can be a gas-solid separator. The gas-solid separation device is used to separate the cracking products and the solid catalyst in the reactor.

[0069] The waste plastic catalytic cracking system provided by the present invention further includes a preheating furnace 7 connected to the raw material inlet of the reactor. The preheating furnace can be a generally commercially available jacket heating device.

[0070] The waste plastic catalytic cracking system provided by the present invention further includes a vaporization furnace 6. The vaporization furnace is connected to the inlet of the preheating furnace 7 through a first pipeline for preheating steam. The vaporization furnace can be a generally commercially available jacket heating device. The material of the first pipeline is stainless steel.

[0071] In certain embodiments of the present invention, the system for catalytic cracking of waste plastics further includes a water storage tank 4 and a water inlet pump 5. The inlet of the water inlet pump is connected to the outlet of the water storage tank; the outlet of the water inlet pump is connected to the inlet of the vaporization furnace. The water in the water storage tank enters the vaporization furnace under the action of the water inlet pump for vaporization. The water storage tank can be self-made or commercially available. The water inlet pump is a commercially available water pump.

[0072] The system for catalytic cracking of waste plastics provided by the present invention further includes a raw material tank 8. The raw material tank stores waste plastic liquefied liquid. The raw material tank is connected to the first pipeline at the inlet of the preheating furnace through a second pipeline. So that the waste plastic liquefied liquid transported from the raw material tank and the water vapor transported from the vaporization furnace converge in the pipeline at the inlet of the preheating furnace and enter the preheating furnace for preheating together. The material of the second pipeline is stainless steel.

[0073] In certain embodiments of the present invention, the system for catalytic cracking of waste plastics further includes a constant temperature heating device 10. The raw material tank is placed in the constant temperature heating device 10 for heating the waste plastic liquefied liquid in the raw material tank to improve the fluidity of the waste plastic liquefied liquid. The constant temperature heating device can be a constant temperature heating furnace or a constant temperature heating box and is commercially available.

[0074] In certain embodiments of the present invention, the system for catalytic cracking of waste plastics further includes a raw material pump 9. The raw material pump is used to transport the waste plastic liquefied liquid in the raw material tank to the preheating furnace and the reactor. The raw material pump is a commercially available raw material pump.

[0075] The system for catalytic cracking of waste plastics provided by the present invention further includes an air supply device 1. The air supply device is connected to the preheating furnace for preheating air. The air supply device is an air compressor or an air generator. Specifically, the air supply device is connected to the preheating furnace through a first gas flowmeter.

[0076] In certain embodiments of the present invention, the system for catalytic cracking of waste plastics further includes an oxygen supply device 2. Specifically, it can be a high-pressure oxygen cylinder and is commercially available. The oxygen supply device is connected to the preheating furnace through a second gas flowmeter.

[0077] The system for catalytic cracking of waste plastics provided by the present invention further includes a primary condensation device 16. The primary condensation device is connected to the gas outlet of the gas-solid separation device for condensing the cracking products and water vapor obtained by gas-solid separation. In certain embodiments of the present invention, the primary condensation device is a straight condenser.

[0078] The waste plastic catalytic cracking system provided by the present invention further includes a liquid collection device 17. The liquid collection device is connected to the outlet of the primary condensation device. Specifically, the outlet of the primary condensation device is connected to the side end of the liquid collection device. The liquids collected in the liquid collection device are pyrolysis oil and condensed water, and the gasoline and diesel in the pyrolysis oil are light fuel oils.

[0079] In certain embodiments of the present invention, the waste plastic catalytic cracking system further includes a secondary condensation device 18. The secondary condensation device is connected to the gas outlet of the liquid collection device. Specifically, the gas outlet at the top of the liquid collection device is connected to the inlet of the secondary condensation device. In certain embodiments of the present invention, the secondary condensation device is a serpentine condenser.

[0080] In certain embodiments of the present invention, the waste plastic catalytic cracking system further includes a tertiary condensation device 20. The tertiary condensation device is connected to the gas outlet of the secondary condensation device. The tertiary condensation device is refrigerated by a refrigeration circulation pump; specifically, the side end of the tertiary condensation device is connected to the refrigeration circulation pump. In certain embodiments of the present invention, the tertiary condensation device is a serpentine condenser, and the refrigeration circulation pump is a low-temperature refrigerating liquid circulation pump.

[0081] In certain embodiments of the present invention, the waste plastic catalytic cracking system further includes a gas collection device 21. The gas collection device is connected to the outlet of the tertiary condensation device. The gas collection device is used for storing gas products and analyzing the product composition.

[0082] In certain embodiments of the present invention, a three-way valve is provided on the pipeline connecting the primary condensation device 16 and the liquid collection device 17. The primary condensation device 16 is connected to the inlet of the three-way valve, the secondary condensation device is connected to the first outlet of the three-way valve, and the second outlet of the three-way valve is connected to the flue gas outlet pipeline, which is the flue gas outlet 23.

[0083] In certain embodiments of the present invention, a cracked gas outlet pipeline is provided on the pipeline connecting the tertiary condensation device 20 and the gas collection device 21. A spherical valve is installed on the cracked gas outlet pipeline, and the outlet of the cracked gas outlet pipeline is the cracked gas outlet 22. The material of the cracked gas outlet pipeline is stainless steel.

[0084] In certain embodiments of the present invention, the primary condensation device, the secondary condensation device, the tertiary condensation device, the liquid collection device and their connecting pipelines are all made of corrosion-resistant materials, such as quartz and / or stainless steel.

[0085] The present invention also provides a method for catalytic cracking of waste plastics using the system described above, including the following steps:

[0086] A) After loading the catalyst into the reactor, start the temperature increase programs of the vaporizer, preheater, and high-temperature heater;

[0087] B) Introduce preheated air into the reactor to fluidize the catalyst in the reactor;

[0088] C) When the temperature in the vaporizer reaches 150 - 350 °C, introduce preheated steam into the reactor to fluidize the catalyst in the reactor;

[0089] D) When the temperature in the reactor reaches 400 - 600 °C, the waste plastic liquefied liquid and steam converge in the pipeline at the inlet of the preheater, and after being heated by the preheater, enter the reactor for catalytic cracking reaction. The products after the reaction are subjected to gas-solid separation, and the gas obtained from the gas-solid separation is condensed to obtain cracked oil and condensed water.

[0090] In step A):

[0091] After loading the catalyst into the reactor, start the temperature increase programs of the vaporizer, preheater, and high-temperature heater.

[0092] In some embodiments of the present invention, loading the catalyst into the reactor includes: loading the catalyst into the reactor from the catalyst feed port of the reactor.

[0093] In some embodiments of the present invention, the catalyst is the FCC waste catalyst after activation treatment. Specifically, the preparation method of the catalyst includes the following steps:

[0094] A1) Roast and screen the FCC waste catalyst;

[0095] A2) Mix the FCC waste catalyst treated in step A1) with an acid solution and carry out a reaction;

[0096] A3) Carry out pore expansion modification on the FCC waste catalyst treated in step A2);

[0097] A4) Load metal oxides on the FCC waste catalyst treated in step A3), and after roasting, obtain the catalyst for catalytic cracking of waste plastics.

[0098] In step A1):

[0099] Roast and screen the FCC waste catalyst.

[0100] In some embodiments of the present invention, the FCC waste catalyst (fluid catalytic cracking catalyst) is from the FCC waste catalyst of the catalytic cracking unit.

[0101] In certain embodiments of the present invention, the calcination temperature is 400 - 700 °C, specifically, it can be 550 °C or 500 °C; the time is 3 - 7 h, specifically, it can be 5 h. The calcination is carried out in a muffle furnace.

[0102] In certain embodiments of the present invention, the particle size of the sieved particles is 50 - 350 mesh; preferably 100 - 300 mesh.

[0103] In step A2):

[0104] Mix the FCC spent catalyst treated in step A1) with an acid solution and carry out a reaction.

[0105] In certain embodiments of the present invention, mixing the FCC spent catalyst treated in step A1) with an acid solution includes: impregnating the FCC spent catalyst treated in step A1) in the acid solution.

[0106] In certain embodiments of the present invention, the acid solution includes at least one of nitric acid solution, sulfuric acid solution, hydrochloric acid solution, oxalic acid solution, acetic acid solution, citric acid solution and tartaric acid solution. The mass concentration of the acid solution is 1% - 50%, specifically, it can be 13%.

[0107] In certain embodiments of the present invention, the mass ratio of the FCC spent catalyst treated in step A1) to the acid solution is 5 - 50:25 - 250; specifically, it can be 20:100.

[0108] In certain embodiments of the present invention, the temperature of the reaction is 30 - 80 °C, specifically, it can be 50 °C; the time is 0.5 - 2 h, specifically, it can be 1 h. The reaction is carried out under stirring conditions, and the stirring speed is 300 - 500 rpm; specifically, it can be 400 rpm. In the present invention, after mixing the FCC spent catalyst treated in step A1) with the acid solution and carrying out the reaction, the partial pore structure of the catalyst can be restored.

[0109] In certain embodiments of the present invention, after the reaction, it further includes: filtration, washing and drying;

[0110] The washing is until neutral.

[0111] The drying temperature is 80 - 150 °C, specifically, it can be 110 °C; the time is 5 - 24 h, specifically, it can be 12 h.

[0112] In step A3):

[0113] Carry out pore expansion modification on the FCC spent catalyst treated in step A2).

[0114] In certain embodiments of the present invention, the method for reaming and modifying includes at least one of an ammonium hexafluorosilicate liquid-phase treatment method, a sodium hydroxide liquid-phase treatment method, and a silicon tetrachloride gas-phase treatment method.

[0115] In certain embodiments of the present invention, the ammonium hexafluorosilicate liquid-phase treatment method includes:

[0116] Mix the FCC waste catalyst treated in step A2), a buffer solution, and an ammonium hexafluorosilicate solution, and carry out a reaction.

[0117] Specifically, it includes:

[0118] Mix the FCC waste catalyst treated in step A2) with the buffer solution, add an aqueous solution of oxalic acid to adjust the pH value, and then dropwise add the ammonium hexafluorosilicate solution under stirring conditions to carry out the reaction.

[0119] The buffer solution includes at least one of an ammonium acetate solution and an ammonium oxalate solution; the concentration of the buffer solution is 0.1 - 1 mol / L; specifically, it can be 0.5 mol / L. The solvent of the buffer solution is water. The mass concentration of the aqueous solution of oxalic acid is 0.1 - 1 mol / L; specifically, it can be 0.5 mol / L.

[0120] The mass concentration of the ammonium hexafluorosilicate solution is 1% - 60%, specifically, it can be 15% or 5%; the solvent is water.

[0121] The dosage ratio of the FCC waste catalyst treated in step A2), the buffer solution, and the ammonium hexafluorosilicate solution is 5 - 50 g : 20 - 100 mL : 30 - 100 mL; specifically, it can be 20 g : 50 mL : 50 mL.

[0122] Add an aqueous solution of oxalic acid to adjust the pH value to 4 - 6, specifically, it can be 5.

[0123] The rotation speed of the stirring is 100 - 600 rpm; specifically, it can be 400 rpm.

[0124] The temperature of the reaction is 20 - 120 °C, specifically, it can be 60 °C or 50 °C; the time is 0.5 - 4 h, specifically, it can be 1 h. The reaction is carried out under stirring conditions, and the rotation speed of the stirring is 100 - 600 rpm; specifically, it can be 400 rpm.

[0125] In certain embodiments of the present invention, after the reaction, it further includes: filtration, washing with distilled water at 50 - 70 °C, and drying. The temperature of the drying is 80 - 150 °C, and the time is 5 - 24 h.

[0126] In certain embodiments of the present invention, after the drying, it further includes:

[0127] Mix the dried FCC spent catalyst and sodium hydroxide solution and carry out a reaction;

[0128] The concentration of the sodium hydroxide solution is 0.1 - 1 mol / L. Specifically, it can be 0.5 mol / L. The solvent of the sodium hydroxide solution is water;

[0129] The dosage ratio of the dried FCC spent catalyst to the sodium hydroxide solution is 5 - 50 g : 10 - 100 mL. Specifically, it can be 50 g : 100 mL;

[0130] The temperature of the reaction is 70 - 100°C. Specifically, it can be 90°C. The time is 0.5 - 2 h. Specifically, it can be 1 h. The reaction is carried out under stirring conditions, and the rotation speed of the stirring is 100 - 600 rpm. Specifically, it can be 400 rpm.

[0131] After the reaction, it further includes: filtration, washing until neutral, and drying. The temperature of the drying is 80 - 150°C. Specifically, it can be 110°C. The time is 5 - 24 h. Specifically, it can be 12 h.

[0132] In some embodiments of the present invention, the sodium hydroxide liquid-phase treatment method includes:

[0133] Mix the FCC spent catalyst after being treated in step A2) and the sodium hydroxide solution and carry out a reaction;

[0134] The concentration of the sodium hydroxide solution is 0.01 - 2 mol / L, preferably 0.1 - 1 mol / L. Specifically, it can be 0.5 mol / L. The solvent of the sodium hydroxide solution is water;

[0135] The dosage ratio of the FCC spent catalyst after being treated in step B) to the sodium hydroxide solution is 5 - 50 g : 10 - 100 mL. Specifically, it can be 50 g : 100 mL;

[0136] The temperature of the reaction is 50 - 150°C, preferably 70 - 100°C. Specifically, it can be 90°C. The time is 0.5 - 4 h, preferably 0.5 - 2 h. Specifically, it can be 1 h;

[0137] The reaction is carried out under stirring conditions, and the rotation speed of the stirring is 100 - 600 rpm. Specifically, it can be 400 rpm.

[0138] In some embodiments of the present invention, after the reaction, it further includes: filtration, washing until neutral, and drying. The temperature of the drying is 80 - 150°C. Specifically, it can be 110°C. The time is 5 - 24 h. Specifically, it can be 12 h.

[0139] In some embodiments of the present invention, the gas-phase treatment method of silicon tetrachloride includes:

[0140] Using N2 as a carrier gas to carry saturated silicon tetrachloride vapor, mixing it with the FCC waste catalyst after being treated in step A2), and carrying out a reaction.

[0141] Specifically, it includes:

[0142] Placing the FCC waste catalyst after being treated in step A2) in a quartz tube, using N2 as a carrier gas, drying it at a constant temperature in a tube furnace, and then using N2 to carry saturated silicon tetrachloride vapor, mixing it with the FCC waste catalyst in the quartz tube, and carrying out a reaction.

[0143] The temperature of the constant-temperature drying is 200 - 400 °C, specifically, it can be 300 °C; the time is 1 - 3 h, specifically, it can be 2 h.

[0144] The flow rate of the carrier gas is 40 - 100 mL / min, specifically, it can be 60 mL / min;

[0145] The temperature of the reaction is 200 - 600 °C, specifically, it can be 400 °C; the time is 1 - 4 h, specifically, it can be 2 h;

[0146] The mass ratio of the silicon tetrachloride to the FCC waste catalyst after being treated in step B) is 1 - 50:1 - 15; specifically, it can be 1:10.

[0147] In some embodiments of the present invention, after the reaction, it further includes: filtering, washing until neutral, and drying. The temperature of the drying is 80 - 150 °C, specifically, it can be 110 °C, and the time is 5 - 24 h, specifically, it can be 12 h.

[0148] In step A4):

[0149] Loading the FCC waste catalyst after being treated in step A3) with metal oxides, and after calcination, obtaining a catalyst for catalytic cracking of waste plastics.

[0150] In some embodiments of the present invention, loading the FCC waste catalyst after being treated in step A3) with metal oxides includes:

[0151] Mixing the FCC waste catalyst after being treated in step A3) with a metal salt solution, and then carrying out a reaction.

[0152] The metal salt includes at least one of lanthanum nitrate, cerium nitrate, iron nitrate, nickel nitrate, copper nitrate and aluminum nitrate. The mass concentration of the metal salt solution is 1% to 8%; specifically, it can be 4.75%. In some embodiments, the metal salt includes lanthanum nitrate and cerium nitrate, and the mass ratio is 1 to 2:1 to 8; specifically, it can be 1.75:3.

[0153] The dosage ratio of the FCC waste catalyst after the treatment in step A3) to the metal salt solution is 20 to 60 g: 30 to 150 mL; specifically, it can be 50 g: 97.5 mL.

[0154] The temperature of the reaction is 50 to 120 °C; specifically, it can be 95 °C; the time is 0.5 to 3 h; specifically, it can be 2 h. The reaction is carried out under stirring, and the rotation speed of the stirring is 300 to 500 rpm; specifically, it can be 400 rpm.

[0155] After the reaction, it further includes: filtration and drying. The temperature of the drying is 80 to 150 °C; specifically, it can be 110 °C; the time is 5 to 24 h; specifically, it can be 12 h.

[0156] In some embodiments of the present invention, the metal oxide includes at least one of lanthanum oxide, cerium oxide, iron oxide, nickel oxide, copper oxide and aluminum oxide.

[0157] In some embodiments of the present invention, the temperature of the roasting is 400 to 700 °C; specifically, it can be 500 °C; the time is 3 to 7 h; specifically, it can be 5 h.

[0158] After obtaining the catalyst for catalytic cracking of waste plastics, after loading the catalyst into the reactor, start the heating-up procedures of the vaporization furnace, preheating furnace and high-temperature heating furnace.

[0159] In some embodiments of the present invention, before starting the heating-up procedures of the vaporization furnace, preheating furnace and high-temperature heating furnace, it further includes: heating the raw material tank. Specifically, it includes: starting the heating-up procedure of the constant-temperature heating device to heat the raw material tank. The temperature of the heating is 50 to 150 °C; specifically, it can be 100 °C.

[0160] In some embodiments of the present invention, the set temperature of the vaporization furnace is 150 to 350 °C; specifically, it can be 200 °C to 300 °C, more specifically, it can be 200 °C; the set temperature of the preheating furnace is 200 to 350 °C; specifically, it can be 300 °C; the set temperature of the reactor is 400 to 600 °C; specifically, it can be 500 °C.

[0161] In step B):

[0162] Preheated air is introduced into the reactor to fluidize the catalyst in the reactor.

[0163] Specifically, before the temperature in the vaporizer reaches the set temperature, preheated air is introduced into the reactor to fluidize the catalyst in the reactor.

[0164] In some embodiments of the present invention, the flow rate of the air is 2 - 10 L / min, specifically, it can be 2.5 - 3.5 L / min; the pressure (gauge pressure) of the air at the inlet of the reactor is 0.20 - 1 MPa; specifically, it can be 0.3 - 0.4 MPa; more specifically, it is 0.35 MPa.

[0165] In step C):

[0166] When the temperature in the vaporizer reaches the set temperature of 150 - 350 °C, preheated steam is introduced into the reactor to fluidize the catalyst in the reactor.

[0167] Specifically, it includes:

[0168] When the temperature in the vaporizer reaches the set temperature of 150 - 350 °C, the feed water pump is started to deliver water to the vaporizer for vaporization. The vaporized steam enters the preheating furnace for preheating and then enters the reactor to fluidize the catalyst in the reactor.

[0169] In some embodiments of the present invention, the rate of delivering water to the vaporizer is 1 - 10 g / min; specifically, it can be 1 - 5 g / min, more specifically, it is 3 g / min.

[0170] In step D):

[0171] When the temperature in the reactor reaches the catalytic cracking reaction temperature of 400 - 600 °C, the waste plastic liquefied liquid and steam converge in the pipeline at the inlet of the preheating furnace, are heated by the preheating furnace and then enter the reactor for catalytic cracking reaction. The products after the reaction are subjected to gas-solid separation. The cracking products and steam obtained from the gas-solid separation are condensed to obtain cracked oil and condensed water.

[0172] In some embodiments of the present invention, the flow rate of the waste plastic liquefied liquid transported from the raw material tank is 0.33 - 0.56 g / s; specifically, it can be 0.5 g / s.

[0173] In some embodiments of the present invention, the viscosity of the waste plastic liquefied liquid at 100 °C is 50 - 5000 mm 2 / s. In the waste plastic liquefied liquid, the total chlorine content is 500 - 3000 μg·g -1 and the total calcium content is 1000 - 6000 μg·g -1, the total iron content is 100 - 3000 μg·g -1 , the total magnesium content is 100 - 1000 μg·g -1 .

[0174] In certain embodiments of the present invention, the method for preparing the waste plastic liquefied liquid includes:

[0175] Mixing waste plastic and component a at 100 - 300 °C to obtain the waste plastic liquefied liquid; component a includes at least one of heavy oil and light diesel oil;

[0176] The waste plastic can be waste plastic that is difficult to recycle, process, and utilize in municipal waste treatment plants, and can also be one or several of polyethylene waste plastic, polyvinyl chloride waste plastic, polypropylene waste plastic, polystyrene waste plastic, and polyethylene terephthalate waste plastic.

[0177] The mass ratio of waste plastic to component a is 1:3 - 10; specifically, it can be 1:7.

[0178] In certain embodiments, component a includes heavy oil and light diesel oil, and the mass ratio of waste plastic, heavy oil, and light diesel oil is 1:2.5 - 3.5:3.5 - 4.5; specifically, it can be 1:3:4. The heavy oil is a fraction with a boiling point higher than 350 °C produced by an atmospheric distillation unit and / or a vacuum distillation unit, specifically, it can be a fraction with a boiling point higher than 350 °C produced by the atmospheric distillation unit and / or the vacuum distillation unit of Yanshan Petrochemical. The light diesel oil is unrefined diesel oil obtained from at least one of an atmospheric distillation unit, a vacuum distillation unit, and a cracking unit, specifically, it can be unrefined diesel oil obtained from at least one of the atmospheric distillation unit, the vacuum distillation unit, and the cracking unit of Yanshan Petrochemical.

[0179] In certain embodiments, the temperature at which the waste plastic and component a are mixed is 120 °C; the mixing is stirring mixing, and the stirring rate is 100 - 500 rpm; specifically, it can be 300 rpm.

[0180] In certain embodiments of the present invention, the mass ratio of the catalyst to the waste plastic liquefied liquid is 1 - 10:1; specifically, it can be 2 - 8:1; more specifically, it is 4:1.

[0181] In certain embodiments of the present invention, the temperature of the catalytic cracking reaction is 500 °C; the time is 80 - 120 s; specifically, it can be 90 - 100 s; more specifically, it is 90 s.

[0182] In certain embodiments of the present invention, after the catalytic cracking reaction, it further includes:

[0183] Using steam to strip the residual oil and gas in the reactor.

[0184] The stripping time is 30 to 60 minutes, specifically, 30 to 40 minutes, and more specifically, 30 minutes. During the stripping process, the rate of delivering water to the vaporizer is 1 to 10 g / min, specifically, 1 to 5 g / min, and more specifically, 3 g / min.

[0185] The cracking products, water vapor and deactivated catalyst obtained by the catalytic cracking reaction are separated by a gas-solid separation device at the top of the reactor, and the cracking products and water vapor are discharged from the gas outlet of the gas-solid separation device.

[0186] In the present invention, the pyrolysis products and water vapor obtained by the gas-solid separation are condensed to obtain pyrolysis oil and condensed water.

[0187] Specifically, they include:

[0188] The cracking products and water vapor obtained by the gas-solid separation are sequentially passed through a primary condensing device, a secondary condensing device and a tertiary condensing device for gas-liquid separation to obtain cracking oil and condensed water, which are collected in a liquid collecting device; the gas product enters a gas collecting device.

[0189] In certain embodiments of the present invention, the condensation temperature of the first-stage condensation device is 20-45°C, specifically, 35°C; the condensation temperature of the second-stage condensation device is -20-0°C, specifically, -10°C; the condensation temperature of the third-stage condensation device is -20-0°C, specifically, -10°C.

[0190] In the present invention, the pyrolysis oil and water vapor obtained by the gas-solid separation are sequentially passed through a primary condensation device, a secondary condensation device and a tertiary condensation device. During the condensation process, the water vapor absorbs hydrogen chloride in the gas and enters a liquid collecting device together with the condensed liquid product. The pyrolysis oil and the acidic aqueous solution containing hydrogen chloride can be separated by liquid-liquid separation.

[0191] In certain embodiments of the present invention, after the stripping is completed, the temperature of the high-temperature heating furnace is increased, and when the temperature in the reactor reaches the regeneration temperature, the oxygen supply system is switched to burn and regenerate the deactivated catalyst in the reactor.

[0192] The regeneration temperature is 580-680° C., specifically, 620° C.; the regeneration time is 30-60 min, specifically, the regeneration time is 40 min.

[0193] After switching to the oxygen supply system, the oxygen supply device is used for supplying oxygen, and the flow rate of oxygen is 0.5-10 L / min. Specifically, it can be 0.8-1.4 L / min. More specifically, it is 1.2 L / min; the pressure (gauge pressure) of oxygen at the inlet of the reactor is 0.20-1 MPa; specifically, it can be 0.20-0.45 MPa; more specifically, it is 0.2 MPa.

[0194] To further illustrate the present invention, the following describes in detail a method and system for catalytic cracking of waste plastics provided by the present invention in conjunction with embodiments, but it should not be construed as a limitation to the protection scope of the present invention.

[0195] Example 1

[0196] Preparation method of catalyst for catalytic cracking of waste plastics:

[0197] 1) Place the FCC waste catalyst in a muffle furnace and calcine it at 550 °C for 5 h, and then sieve to obtain particles with a mesh size of 100-300;

[0198] 2) Weigh 20 g of the FCC waste catalyst obtained in step 1) and immerse it in 100 g of a nitric acid solution with a mass concentration of 13%, and react at 50 °C for 1 h under stirring conditions (rotation speed of 400 rpm); after the reaction, filter and wash until neutral, and dry at 110 °C for 12 h;

[0199] 3) Use the ammonium hexafluorosilicate liquid-phase treatment method to perform pore-expanding modification on the FCC waste catalyst obtained in step 2):

[0200] Mix 20 g of the FCC waste catalyst obtained in step 2) with 50 mL of an aqueous solution of ammonium acetate with a concentration of 0.5 mol / L, then add an aqueous solution of oxalic acid with a concentration of 0.5 mol / L to adjust the pH value to 5, and then dropwise add 50 mL of an aqueous solution of ammonium hexafluorosilicate with a mass concentration of 15% under stirring conditions (rotation speed of 400 rpm), react at 60 °C for 1 h under stirring (rotation speed of 400 rpm), filter after the reaction, wash with distilled water at 60 °C, and dry at 110 °C for 12 h;

[0201] 4) Mix 50 g of the catalyst obtained in step 3) with 97.5 mL of a metal salt solution including lanthanum nitrate and cerium nitrate (mass concentration of 4.75%, mass ratio of lanthanum nitrate to cerium nitrate is 1.75:3), and react at 95 °C for 2 h under stirring conditions (rotation speed of 400 rpm); filter after the reaction and dry at 110 °C for 12 h;

[0202] 5) Place the supported catalyst obtained in step 4) in a muffle furnace and calcine it at 500 °C for 5 h to obtain catalyst A for catalytic cracking of waste plastics.

[0203] Example 2

[0204] Preparation method of catalyst for catalytic cracking of waste plastics:

[0205] 1) Place the FCC waste catalyst in a muffle furnace and calcine it at 550 °C for 5 h. Then, sieve to obtain particles with a mesh size of 100 - 300;

[0206] 2) Weigh 20 g of the FCC waste catalyst obtained in step 1) and immerse it in 100 g of a nitric acid solution with a mass concentration of 13%. React at 50 °C for 1 h under stirring conditions (rotation speed of 400 rpm); After the reaction, filter and wash until neutral, and dry at 110 °C for 12 h;

[0207] 3) Use the ammonium hexafluorosilicate liquid-phase treatment method to expand the pores and modify the FCC waste catalyst obtained in step 2):

[0208] Mix 20 g of the FCC waste catalyst obtained in step 2) with 50 mL of an aqueous solution of ammonium acetate with a concentration of 0.5 mol / L, then add an aqueous solution of oxalic acid with a concentration of 0.5 mol / L to adjust the pH value to 5. Then, under stirring conditions (rotation speed of 400 rpm), dropwise add 50 mL of an aqueous solution of ammonium hexafluorosilicate with a mass concentration of 5%. React at 50 °C for 1 h under stirring (rotation speed of 400 rpm). After the reaction, filter, wash with distilled water at 60 °C, and dry at 110 °C for 12 h;

[0209] Mix 50 g of the dried FCC waste catalyst with 100 mL of an aqueous solution of sodium hydroxide with a concentration of 0.5 mol / L, and react at 90 °C for 1 h under stirring conditions (rotation speed of 400 rpm). After the reaction, filter and wash until neutral, and dry at 110 °C for 12 h;

[0210] 4) Mix 50 g of the FCC waste catalyst obtained in step 3) with 97.5 mL of a metal salt solution containing lanthanum nitrate and cerium nitrate (mass concentration of 4.75%, mass ratio of lanthanum nitrate to cerium nitrate is 1.75:3). React at 95 °C for 2 h under stirring (rotation speed of 400 rpm); After the reaction, filter and dry at 110 °C for 12 h;

[0211] 5) Place the supported FCC waste catalyst obtained in step 4) in a muffle furnace and calcine it at 500 °C for 5 h to obtain catalyst B for catalytic cracking of waste plastics.

[0212] Example 3

[0213] Preparation method of catalyst for catalytic cracking of waste plastics:

[0214] 1) Place the FCC waste catalyst in a muffle furnace and calcine it at 550 °C for 5 h. Then, sieve to obtain particles with a mesh size of 100 - 300;

[0215] 2) Weigh 20 g of the FCC spent catalyst obtained in step 1) and immerse it in 100 g of a nitric acid solution with a mass concentration of 13%. React at 50 °C for 1 h under stirring conditions (rotation speed of 400 rpm); after the reaction, filter and wash until neutral, and dry at 110 °C for 12 h;

[0216] 3) Use the sodium hydroxide liquid-phase treatment method to perform pore-expanding modification on the FCC spent catalyst obtained in step 2):

[0217] Mix 50 g of the FCC spent catalyst obtained in step 2) with 100 mL of an aqueous sodium hydroxide solution with a concentration of 0.5 mol / L. React at 90 °C for 1 h under stirring conditions (rotation speed of 400 rpm). After the reaction, filter and wash until neutral, and dry at 110 °C for 12 h;

[0218] 4) Mix 50 g of the FCC spent catalyst obtained in step 3) with 97.5 mL of a metal salt solution containing lanthanum nitrate and cerium nitrate (mass concentration of 4.75%, mass ratio of lanthanum nitrate to cerium nitrate is 1.75:3), and react at 95 °C for 2 h under stirring (rotation speed of 400 rpm); after the reaction, filter and dry at 110 °C for 12 h;

[0219] 5) Place the supported FCC spent catalyst obtained in step 4) in a muffle furnace and calcine at 500 °C for 5 h to obtain the catalyst C for catalytic cracking of waste plastics.

[0220] Example 4

[0221] Preparation method of the catalyst for catalytic cracking of waste plastics:

[0222] 1) Place the FCC spent catalyst in a muffle furnace and calcine at 500 °C for 5 h, and then sieve to obtain particles with a size of 100 - 300 mesh;

[0223] 2) Weigh 20 g of the FCC spent catalyst obtained in step 1) and immerse it in 100 g of a nitric acid solution with a mass concentration of 13%. React at 50 °C for 1 h under stirring conditions (rotation speed of 400 rpm); after the reaction, filter and wash until neutral, and dry at 110 °C for 12 h;

[0224] 3) Use the silicon tetrachloride gas-phase treatment method to perform pore-expanding modification on the FCC spent catalyst obtained in step 2):

[0225] Place 20 g of the FCC spent catalyst obtained in step 2) in a quartz tube. Using N2 as the carrier gas (flow rate: 60 mL / min), dry it at a constant temperature of 300 °C in a tube furnace for 2 h. Then, use N2 to carry saturated silicon tetrachloride vapor (the mass ratio of silicon tetrachloride to the FCC spent catalyst obtained in step 2) is 1:10), mix it with the FCC spent catalyst in the quartz tube, and react at 400 °C for 2 h; after the reaction, filter and wash until neutral, and dry at 110 °C for 12 h;

[0226] 4) Mix 50 g of the FCC spent catalyst obtained in step 3) with 97.5 mL of a metal salt solution containing lanthanum nitrate and cerium nitrate (mass concentration: 4.75%, and the mass ratio of lanthanum nitrate to cerium nitrate is 1.75:3). Then, react at 95 °C for 2 h under stirring (rotation speed: 400 rpm); after the reaction, filter and dry at 110 °C for 12 h;

[0227] 5) Place the supported FCC spent catalyst obtained in step 4) in a muffle furnace and calcine it at 500 °C for 5 h to obtain catalyst D for catalytic cracking of waste plastics.

[0228] Apply the catalysts for catalytic cracking of waste plastics prepared in Examples 1 to 4 to the catalytic cracking of waste plastics. The preparation method of the waste plastic liquefied liquid includes:

[0229] Stir and mix waste plastics, heavy oil, and light diesel at 120 °C (stirring rate: 300 rpm) to obtain a waste plastic liquefied liquid; the mass ratio of the waste plastics, heavy oil, and light diesel is 1:3:4; the waste plastics are waste plastics that are difficult to recycle, process, and utilize in municipal waste treatment plants.

[0230] The viscosity of the waste plastic liquefied liquid at 100 °C is 280 mm 2 / s. In the waste plastic liquefied liquid, the total chlorine content is 849 μg·g -1 , the total calcium content is 1138 μg·g -1 , the total iron content is 430 μg·g -1 , and the total magnesium content is 130 μg·g -1 .

[0231] The method for catalytic cracking of waste plastics using the waste plastic catalytic cracking system as shown in Figure 1 includes the following steps:

[0232] 1) Load 200 g of the catalyst into a conical spouted bed reactor, and turn on the heating program of the constant temperature heating box to heat the raw material tank; the heating temperature is 100 °C;

[0233] Start the temperature increase program for the vaporization furnace, preheating furnace, and high-temperature heating furnace to increase the temperature; the set temperature of the vaporization furnace is 200°C, the set temperature of the preheating furnace is 300°C, and the set temperature of the reactor is 500°C;

[0234] 2) Before the temperature in the vaporization furnace reaches 200°C, introduce preheated air into the reactor to fluidize the catalyst in the reactor; the air flow rate is 2.5 - 3.5 L / min, and the pressure (gauge pressure) of the air at the reactor inlet is 0.35 MPa;

[0235] 3) After the temperature in the vaporization furnace reaches 200°C, start the atomization system, start the feed water pump to transport water to the vaporization furnace for vaporization. After the vaporized water vapor enters the preheating furnace for preheating, it enters the reactor to fluidize the catalyst in the reactor; the rate of transporting water to the vaporization furnace is 3 g / min;

[0236] 4) When the temperature in the reactor reaches the catalytic cracking reaction temperature of 500°C, start the feeding system. The waste plastic liquefied liquid (the flow rate of the waste plastic liquefied liquid transported from the raw material tank is 0.5 g / s.) is mixed with water vapor in the inlet pipeline of the preheating furnace, and after being heated by the preheating furnace, it enters the reactor for catalytic cracking reaction. The catalytic cracking reaction time is 90 s;

[0237] The mass ratio of the catalyst to the waste plastic liquefied liquid is 4:1;

[0238] The cracked products, water vapor, and deactivated catalyst obtained from the catalytic cracking reaction are separated by the gas-solid separation device at the top of the reactor. The cracked products and water vapor are discharged from the gas outlet of the gas-solid separation device;

[0239] After the catalytic cracking reaction ends, start the stripping system, use water vapor to strip the residual oil and gas in the reactor, the stripping time is 30 min, and the rate of transporting water to the vaporization furnace is 3 g / min;

[0240] The obtained cracked products and water vapor are successively passed through a first-stage condensation device (temperature 35°C), a second-stage condensation device (temperature -10°C), and a third-stage condensation device (temperature -10°C) for gas-liquid separation to obtain cracked oil and condensed water, which are collected in the liquid collection device. Through liquid-liquid separation, cracked oil is obtained; the gasoline and diesel in the cracked oil are light fuel oils; the gas products enter the gas collection device;

[0241] 5) Shut down the stripping system, switch the oxygen supply system, supply gas using the oxygen supply device, and carry out coke burning regeneration on the deactivated catalyst in the reactor. The regeneration temperature is 620°C, the regeneration time is 40 min, the oxygen flow rate is 1.2 L / min, and the pressure (gauge pressure) of the oxygen at the reactor inlet is 0.2 MPa.

[0242] The catalysts for catalytic cracking of waste plastics prepared in Examples 1 to 4 were respectively applied to the catalytic cracking of waste plastics, and the effects are shown in Table 1.

[0243] Table 1 Effects of the catalysts for catalytic cracking of waste plastics prepared in Examples 1 to 4 when applied to the catalytic cracking of waste plastics

[0244]

[0245] As can be seen from Table 1, the system and method provided by the present invention are conducive to the conversion of municipal solid waste plastics into light fuel oil, and the chlorine content in the cracked oil is greatly reduced, significantly reducing the recycling cost of municipal solid waste plastics and enabling the high-value utilization of inferior waste plastics.

[0246] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A system for catalytic cracking of waste plastics, comprising: A reactor; a raw material feed inlet is provided at the bottom of the reactor; a catalyst feed inlet and a gas-solid separation device are provided at the top of the reactor; The gas-solid separation device is used to separate the cracking products and the solid catalyst in the reactor; the reactor is selected from one or more of a conical jet bed reactor, a bubbling fluidized bed reactor, a particulate fluidized bed reactor, a boiling bed reactor, a turbulent bed reactor, and a riser reactor; A high-temperature heating furnace; the reactor is placed in the high-temperature heating furnace; A preheating furnace connected to the raw material feed inlet of the reactor; A vaporizer connected to the inlet of the preheating furnace through a first pipeline; A raw material tank connected to the first pipeline at the inlet of the preheating furnace through a second pipeline; waste plastic liquefied liquid is stored in the raw material tank; A constant-temperature heating device; The raw material tank is placed in the constant-temperature heating device; An air supply device; the air supply device is connected to the preheating furnace through a first gas flow meter; An oxygen supply device; the oxygen supply device is connected to the preheating furnace through a second gas flow meter; A primary condensation device connected to the gas outlet of the gas-solid separation device; A liquid collection device connected to the outlet of the primary condensation device; The liquid collected in the liquid collection device is cracked oil and condensed water; A secondary condensation device connected to the gas outlet of the liquid collection device; A tertiary condensation device connected to the gas outlet of the secondary condensation device; A gas collection device connected to the outlet of the tertiary condensation device.

2. The system according to claim 1, wherein, It further includes: A water storage tank and a water inlet pump; The inlet of the water inlet pump is connected to the outlet of the water storage tank; The outlet of the water inlet pump is connected to the inlet of the vaporizer.

3. The system according to claim 1, wherein, It further includes: a raw material pump; The raw material pump is used to transport the waste plastic liquefied liquid in the raw material tank to the preheating furnace and the reactor.

4. The system according to claim 1, The secondary condensation device is a serpentine condenser; The tertiary condensation device is a serpentine condenser, and the tertiary condensation device is refrigerated by a refrigeration circulation pump; The primary condensation device is a straight condenser.

5. A method for catalytic cracking of waste plastics using the system according to any one of claims 1 to 4, comprising the following steps: A) After loading the catalyst in the reactor, turn on the heating programs of the vaporizer, the preheating furnace, and the high-temperature heating furnace; B) Introduce preheated air into the reactor to fluidize the catalyst in the reactor; C) When the temperature in the vaporizer reaches 150 - 350 °C, introduce preheated steam into the reactor to fluidize the catalyst in the reactor; D) When the temperature in the reactor reaches 400 - 600 °C, the waste plastic liquefied liquid and steam converge in the pipeline at the inlet of the preheating furnace, are heated by the preheating furnace, and then enter the reactor for catalytic cracking reaction. The reaction products are subjected to gas-solid separation, and the cracked products and steam obtained from the gas-solid separation are condensed to obtain cracked oil and condensed water.

6. The method according to claim 5, wherein In step A), the set temperature of the vaporizer is 150 - 350 °C, the set temperature of the preheater is 200 - 350 °C, and the set temperature of the reactor is 400 - 600 °C; The flow rate of the air is 2 - 10 L / min, and the pressure of the air at the inlet of the reactor is 0.20 - 1 MPa.

7. The method according to claim 5, characterized in that In step C), during the process of introducing preheated steam into the reactor, the rate of water delivery to the vaporizer is 1 - 10 g / min; In step D), the flow rate of the waste plastic liquefied liquid transported from the raw material tank is 0.33 - 0.56 g / s; The time of the catalytic cracking reaction is 80 - 120 s.

8. The method according to claim 5, characterized in that The mass ratio of the catalyst to the waste plastic liquefied liquid is 1 - 10:1.

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