Method for increasing naphtha yield by blending waste plastics and hydrocracking

Abstract

The invention discloses a method for increasing naphtha yield by blending and hydrocracking waste plastics, which comprises the following steps: adding the waste plastics into a batch reactor with a stirring function, adding a composite solvent and a potassium-based catalyst, liquefying the waste plastics, and separating a liquid-solid mixture generated by liquefying to obtain liquefied waste plastics; the method comprises the following steps: by taking liquefied waste plastics as a material flow I and a wax oil raw material with a dry point of not greater than 500 DEG C as a material flow II, mixing, passing through a fixed bed reactor filled with a hydrocracking catalyst, and carrying out a hydrocracking reaction to obtain a base oil product; wherein the composite solvent is obtained by mixing a solvent I, a solvent II and a solvent III according to the mass ratio of (2.5-6): (0.5-2): 1. According to the invention, the waste plastics are liquefied and blended with the hydrocracking device to produce more naphtha, so that the waste plastics are recycled to a certain extent, the landfill amount is reduced, the influence of the waste plastics on air, soil, aquatic and marine organisms is reduced, and the problem of environmental pollution is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrocracking, and discloses a method for producing more naphtha by blending waste plastics, and mainly relates to a method for producing more naphtha by blending waste plastics with wax oil and hydrocracking. Background Art

[0002] The production of plastic materials such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET) and polyvinyl chloride (PVC) is increasing every year. These plastics are widely used in packaging, construction, agriculture, electrical and electronic appliances, and healthcare applications. Plastics have some unique properties such as outstanding versatility, light weight, strong, water-resistant, low cost, etc., which make them indispensable to modern civilization. However, most plastic items have a very short lifespan. Due to poor biodegradation rate, plastic waste occupies land for a longer time. Only 1-3wt% of the hydrocarbon content in plastic is degraded in 100 years. Therefore, reducing the overall amount of plastic waste landfill has become a huge environmental issue. Today, landfill space is decreasing, while the cost of landfill is soaring. Some countries are introducing new legislation to reduce the amount of waste plastic sent to landfills. In landfills, plastic materials are a burden on the environment, a waste of resources, a source of pollutants, and a source of greenhouse gases such as methane. Incineration of this plastic waste for energy generation results in the emission of particulate matter and harmful gases, including unburned hydrocarbons, nitrogen oxides and sulfur oxides, which is highly unacceptable from an environmental point of view. Therefore, incineration and landfill are not the preferred routes for plastic waste management, and plastic waste needs to be handled in a more sustainable and environmentally friendly way. Recycling is an alternative to landfill or incineration. It not only protects the environment but also helps to convert potential resources into useful products. Among various recycling methods, tertiary recycling, which converts waste plastic materials into petrochemical products and fuels, has received increasing attention worldwide. Tertiary recycling is an economical and environmentally friendly way to recycle plastics and is recognized as the most promising method among various waste plastic management methods. Tertiary recycling can be carried out through chemical or thermal recovery technologies. For condensation polymers, solvent degradation, glycolysis, methanolysis and hydrolysis can be carried out, while addition polymers (PE, PP, PS and PVC) are subjected to thermal recovery technologies such as gasification, thermal cracking or pyrolysis, catalytic cracking and hydrocracking.

[0003] Chinese patent CN202111595049.2 discloses a method for preparing base oil, comprising the following steps: (1) passing waste plastics through a fixed bed reactor A filled with a catalytic cracking catalyst to perform catalytic cracking treatment to obtain material stream I; (2) mixing material stream I with hydrogen, and then cracking it through a fixed bed hydrogenation reactor B filled with a hydrocracking catalyst to obtain material stream II; (3) passing material stream II through a fixed bed reactor C filled with an isomerization dewaxing catalyst to isomerize, and separating to obtain a base oil product. However, this method has high energy consumption, and the conversion of waste plastics into base oil products requires a catalytic cracking-hydrocracking-hydroisomerization process, and the catalytic cracking reaction temperature is 380-650°C.

[0004] Chinese patent CN202111276209.7 discloses a method and system for pyrolysis recovery of waste plastics, which includes allowing chlorine-containing waste plastics to enter a waste plastic preliminary melting and liquefaction dechlorination unit for hot melt dechlorination treatment to obtain a gaseous material containing hydrogen chloride and a dechlorinated waste plastic liquid material; allowing the dechlorinated waste plastic liquid material and a high-temperature pyrolysis raw material to enter a material mixing unit for mixing, respectively, to obtain a mixed pyrolysis raw material; allowing the mixed pyrolysis raw material to enter a pyrolysis reaction unit for pyrolysis to obtain pyrolysis gaseous products and coke; allowing the pyrolysis gaseous products to enter a separation unit for separation to obtain dry gas and liquefied gas, gasoline fractions, diesel fractions, and wax oil fractions. Realizing the resource utilization of waste plastics can also avoid the coking phenomenon of furnace tubes during the heating process of liquefied waste plastic oil. However, this method uses a high-temperature hot melt method of 400-500°C to liquefy waste plastics. The high-temperature hot melt method will cause the waste plastics to form a high-viscosity polymer melt during the melting process, and the polymer melt mixed fluid may cause problems such as device blockage and coking. In addition, when the pyrolysis reaction is carried out in the pyrolysis reaction unit, the reaction temperature is 480-650° C. This method requires a relatively high reaction temperature and the reaction conditions are difficult to control.

[0005] Chinese patent CN116064071A discloses a method for treating chlorine-containing waste plastics using a delayed coking device, comprising the following steps: S1, heating, mixing and melting the chlorine-containing waste plastic raw materials to be treated in a raw material mixing and melting device (2) to obtain a waste plastic mixture material; mixing the waste plastic mixture material with a high-temperature solvent and entering a liquefaction dechlorination reactor (3) to perform dechlorination treatment under stripping conditions to obtain a gas phase material containing hydrogen chloride and a dechlorinated waste plastic liquid phase material. However, the waste plastic liquefaction process requires the dechlorinated waste plastic phase material to enter a high-temperature liquefaction unit for heating treatment, and the high-temperature liquefaction unit includes a screw pump. In this process, the plastic liquefaction is subjected to uneven heating, which is prone to coking and fouling. Summary of the invention

[0006] The technical problem to be solved by the present invention is to efficiently transform and utilize waste plastics to realize the resource utilization of waste plastics. The method of the present invention optimizes the anti-poisoning ability of the hydrocracking catalyst, liquefies the waste plastics and then mixes them into the hydrocracking reaction, thereby achieving the goal of producing more naphtha and avoiding the pollution problem caused by waste plastics.

[0007] In order to solve the above problems, the present invention provides a method for producing more naphtha by mixing and hydrocracking waste plastics, which method comprises the following steps:

[0008] (1) adding waste plastics into an intermittent reactor with a stirring function, adding a composite solvent and a potassium-based catalyst, liquefying the waste plastics, and separating a liquid-solid mixture produced by liquefaction to obtain liquefied waste plastics;

[0009] (2) liquefied waste plastics as material stream I and wax oil raw materials with a dry point of ≯500°C as material stream II are mixed and passed through a fixed bed reactor filled with a hydrocracking catalyst to perform a hydrocracking reaction to obtain a base oil product;

[0010] Wherein, the composite solvent in step (1) is obtained by mixing solvent I, solvent II and solvent III in a mass ratio of (2.5-6): (0.5-2): 1.

[0011] In the method for producing more naphtha by mixing and hydrocracking waste plastics of the present invention, the solvent I is at least one of ethylene glycol, n-propanol, isobutanol, isopentanol and 2-phenylethanol; the solvent II is at least one of flavonoids, lignans and acetone; and the solvent III is at least one of cyclohexane and petroleum ether.

[0012] The method for producing more naphtha by refining and hydrocracking waste plastics of the present invention comprises the following steps: in step (1), the composite solvent is obtained by mixing solvent I, solvent II and solvent III in a mass ratio of (4-6): (1.5-2):.

[0013] The method for producing more naphtha by mixing and hydrocracking waste plastics of the present invention comprises the following steps: in step (1), the mass ratio of the composite solvent to the waste plastics is (3-8):1, preferably 3-5:1.

[0014] In the method for producing naphtha by refining and hydrocracking waste plastics of the present invention, in step (1), the mass ratio of the potassium-based catalyst to the waste plastics is 0.3 to 0.5:1; it should be noted that the present invention does not particularly limit the type and preparation method of the potassium-based catalyst, and the potassium-based catalyst can be a commercially available potassium-based catalyst or prepared by conventional methods.

[0015] The method for producing more naphtha by blending and hydrocracking waste plastics of the present invention comprises the following steps: in step (1), the waste plastics include at least one of polyethylene (PE), polypropylene (PP) and polystyrene (PS).

[0016] In the method for producing more naphtha by refining and hydrocracking waste plastics of the present invention, in step (2), the mixing ratio of the material flow I and the material flow II is (15wt%-35wt%): (85wt%-65wt%), preferably 15-20wt%: 70-80wt%.

[0017] The method for producing more naphtha by refining and hydrocracking waste plastics of the present invention, in step (2), the hydrocracking catalyst comprises the following components: (a) at least one of zirconium oxide, titanium oxide, iron oxide, and potassium oxide; (b) at least one of USY molecular sieve, ZSM-5 molecular sieve, and SBA-16 molecular sieve; (c) amorphous silica-alumina; (d) at least one of nickel oxide, tungsten oxide, and phosphoric acid; It should be noted that the present invention does not particularly limit the source of the hydrocracking catalyst, which can be a commercially available hydrocracking catalyst or prepared by conventional methods.

[0018] The method for producing more naphtha by blending and hydrocracking waste plastics of the present invention comprises the following steps: in step (1), the pressure of the reactor is 4-10 MPa, the temperature is 250-500° C., and the residence time of the waste plastics in the reactor is 0.5-6 h; preferably, the pressure of the reactor is 6-8 MPa, the temperature is 280-400° C., and the residence time of the waste plastics in the reactor is 0.5-3 h.

[0019] The method for producing more naphtha by mixing and hydrocracking waste plastics of the present invention comprises the following steps: in step (2), the temperature of the hydrocracking reaction is 365-380°C, the reaction pressure is 14-17Mpa, and the air velocity is 0.5-1.2h -1 , hydrogen-to-oil ratio 700-1500:1; preferably, the air velocity is 0.8-1.0h -1 , hydrogen-oil ratio 1000-1500:1.

[0020] The method of the present invention uses a composite solvent and a potassium-based catalyst to liquefy waste plastics. Compared with the thermal treatment method of high-temperature hot melt in the prior art, the liquefaction treatment method of the present invention is more environmentally friendly, simple to operate, and reduces production costs. In the process of liquefying waste plastics, the present invention uses a composite solvent and a potassium-based catalyst to cooperate, and can liquefy waste plastics well at a certain temperature and pressure, providing a basis for subsequent reactions. Among them, the potassium-based catalyst can promote the decomposition reaction of waste plastics to tilt towards non-wax oil products, through the breakage and recombination of molecules, and the similar compatibility principle of composite solvents, so as to obtain more other valuable liquid products. The present invention liquefies waste plastics and mixes them with a hydrocracking device to produce more naphtha, which realizes the recycling and reuse of waste plastics to a certain extent, reduces the amount of landfill, reduces the impact of waste plastic garbage on air, soil, and aquatic and marine life, and reduces environmental pollution problems. At the same time, the waste plastic blending and hydrocracking can be used for reuse, without the need to build or transform the device, saving costs. The method of the present invention improves the yield of naphtha. DETAILED DESCRIPTION

[0021] The specific implementation methods of the present invention are further described below to make the technical solutions of the present invention easier to understand and grasp, but the present invention is not limited thereto. The experimental methods in the following examples are conventional methods unless otherwise specified; the reagents and materials can be obtained from commercial sources unless otherwise specified.

[0022] Source of raw materials: Ethylene glycol, n-propanol, isobutanol, isopentanol, 2-phenylethanol, cyclohexane, acetone and other raw materials are from the brand Innochem, which are commercially available reagents; flavonoid raw materials are from the brand Aladdin, which are commercially available reagents; lignans are purchased from Hengyuan Biotechnology, which are commercially available reagents; potassium carbonate and others are all commercially available reagents, industrial grade.

[0023] Preparation of potassium-based catalyst 1:

[0024] 50g of alumina catalyst carrier was dispersed in water, 8g of potassium carbonate was added under vigorous stirring, and stirred at room temperature for 24h. The suspension was evaporated to dryness and calcined at 550°C for 4h to obtain potassium-based catalyst A1.

[0025] Preparation of potassium-based catalyst 2:

[0026] 50g of the catalyst magnesium oxide carrier was dispersed in water, 8g of potassium carbonate was added under vigorous stirring conditions, and stirred at room temperature for 24h. The suspension was evaporated to dryness and calcined at 550°C for 4h to obtain potassium-based catalyst A2.

[0027] Preparation of potassium-based catalyst 3:

[0028] 50g of the zirconium oxide carrier catalyst was dispersed in water, 8g of potassium carbonate was added under vigorous stirring conditions, and stirred at room temperature for 24h. The suspension was evaporated to dryness and calcined at 550°C for 4h to obtain potassium-based catalyst A3.

[0029] Preparation of hydrocracking catalyst 1:

[0030] (1) Weigh 36.7 g of titanium oxide (68 wt% on a dry basis), 62.8 g of amorphous silica alumina (71.6 wt% on a dry basis), and 32.6 g of USY molecular sieve (92 wt% on a dry basis), mix the three solid powders thoroughly, add a pre-prepared dilute nitric acid solution, knead for 15 minutes, extrude through a 2.6 mm orifice plate, dry at 120°C for 2 h, and then calcine at 540°C in an air atmosphere for 4 h to obtain a catalyst carrier.

[0031] (2) 100 g of the catalyst carrier was first impregnated with 80 mL of a 20 wt% potassium carbonate aqueous solution for 3 h, then vacuum dried at 100° C. for 12 h, then impregnated with an equal volume of an impregnation solution of 51.6 g of nickel nitrate and 70.01 g of ammonium metatungstate dissolved in 100 mL of water for 2 h, dried at 120° C. for 4 h, and calcined at 500° C. in an air atmosphere for 4 h to obtain a hydrocracking catalyst B1.

[0032] Preparation of Hydrocracking Catalyst 2:

[0033] (1) Weigh 25.5 g of zirconium oxide (98 wt% on a dry basis), 62.8 g of amorphous silica alumina (71.6 wt% on a dry basis), and 32.6 g of USY molecular sieve (92 wt% on a dry basis), mix the three solid powders thoroughly, add a pre-prepared dilute nitric acid solution, knead for 15 minutes, extrude through a 2.6 mm orifice plate, dry at 120°C for 2 h, and then calcine at 540°C in air for 4 h to obtain a catalyst carrier.

[0034] (2) 100 g of the catalyst carrier was first impregnated with 80 mL of a 20 wt% potassium carbonate aqueous solution for 3 h, then vacuum dried at 100° C. for 12 h, then impregnated with an equal volume of an impregnation solution of 51.6 g of nickel nitrate and 70.01 g of ammonium metatungstate dissolved in 100 mL of water for 2 h, dried at 120° C. for 4 h, and calcined at 500° C. in an air atmosphere for 4 h to obtain a hydrocracking catalyst B2.

[0035] Preparation of Hydrocracking Catalyst 3:

[0036] (1) Weigh 25 g of iron oxide, 62.8 g of amorphous silica-alumina (71.6 wt% on a dry basis), and 32.6 g of USY molecular sieve (92 wt% on a dry basis), mix the three solid powders thoroughly, add a pre-prepared dilute nitric acid solution, knead for 15 minutes, extrude through a 2.6 mm orifice plate, dry at 120°C for 2 h, and then calcine at 540°C in an air atmosphere for 4 h to obtain a catalyst carrier.

[0037] (2) 100 g of the catalyst carrier was first impregnated with 80 mL of a 20 wt% potassium carbonate aqueous solution for 3 h, then vacuum dried at 100° C. for 12 h, then impregnated with an equal volume of an impregnation solution of 51.6 g of nickel nitrate and 70.01 g of ammonium metatungstate dissolved in 100 mL of water for 2 h, dried at 120° C. for 4 h, and calcined at 500° C. in an air atmosphere for 4 h to obtain a hydrocracking catalyst B3.

[0038] Preparation of Hydrocracking Catalyst 4:

[0039] (1) Weigh 36.7 g of titanium oxide (68 wt% on a dry basis), 62.8 g of amorphous silica alumina (71.6 wt% on a dry basis), and 32.6 g of USY molecular sieve (92 wt% on a dry basis), mix the three solid powders thoroughly, add a pre-prepared dilute nitric acid solution, knead for 15 minutes, extrude through a 2.6 mm orifice plate, dry at 120°C for 2 h, and then calcine at 540°C in an air atmosphere for 4 h to obtain a catalyst carrier.

[0040] (2) 100 g of the catalyst carrier was impregnated with an impregnation solution of 51.6 g of nickel nitrate and 70.01 g of ammonium metatungstate dissolved in 100 mL of water in equal volumes for 2 h, dried at 120° C. for 4 h, and calcined at 500° C. in air atmosphere for 4 h to obtain a hydrocracking catalyst B4.

[0041] Example 1

[0042] (1) Add polyethylene (PE) block waste plastics into an intermittent reactor with a stirring function, add ethylene glycol, flavonoids, and cyclohexane in a mass ratio of 6:2:1 as a composite solvent, and the mass ratio of the composite solvent added to the waste plastics is 8.0. The mass ratio of potassium-based catalyst A1 to the waste plastics is 0.3:1. The reaction pressure is 4.0 MPa, the reaction temperature is 500°C, the reaction time is 0.5 h, the stirring speed is 2000 rpm, and the obtained solid-liquid mixture is solid-liquid separated to obtain liquefied waste plastics.

[0043] (2) Liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 15wt%:85wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B1, the catalyst filling volume is 200mL, the cracking reaction temperature is 380°C, the reaction pressure is 15.5Mpa, and the space velocity is 1.0h -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0044] Example results: C5 + liquid yield is 95.5wt%, the product is cut by actual boiling point, heavy naphtha yield is 59.3wt%, light diesel yield is 16.5wt%, heavy diesel yield is 12.4wt%, and tail oil yield is 7.3wt%.

[0045] Example 2

[0046] (1) Add polyethylene (PE) block waste plastics into an intermittent reactor with a stirring function, add ethylene glycol, flavonoids, and cyclohexane in a mass ratio of 6:2:1 as a composite solvent, and the mass ratio of the composite solvent added to the waste plastics is 8.0. The mass ratio of potassium-based catalyst A1 to the waste plastics is 0.3:1. The reaction pressure is 4.0 MPa, the reaction temperature is 500°C, the reaction time is 0.5 h, the stirring speed is 2000 rpm, and the obtained solid-liquid mixture is solid-liquid separated to obtain liquefied waste plastics.

[0047] (2) Liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 15wt%:85wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B2, the catalyst filling volume is 200mL, the cracking reaction temperature is 380°C, the reaction pressure is 15.5Mpa, and the space velocity is 1.0h -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0048] Example results: C5 + liquid yield is 94.5wt%, the product is cut by actual boiling point, heavy naphtha yield is 55.1wt%, light diesel yield is 18.2wt%, heavy diesel yield is 13.4wt%, and tail oil yield is 7.8wt%.

[0049] Example 3

[0050] (1) Add polyethylene (PE) block waste plastics into an intermittent reactor with a stirring function, add ethylene glycol, flavonoids, and cyclohexane in a mass ratio of 6:2:1 as a composite solvent, and the mass ratio of the composite solvent added to the waste plastics is 8.0. The mass ratio of potassium-based catalyst A1 to the waste plastics is 0.3:1. The reaction pressure is 4.0 MPa, the reaction temperature is 500°C, the reaction time is 0.5 h, the stirring speed is 2000 rpm, and the obtained solid-liquid mixture is solid-liquid separated to obtain liquefied waste plastics.

[0051] (2) Liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 15wt%:85wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B3, the catalyst filling volume is 200mL, the cracking reaction temperature is 380°C, the reaction pressure is 15.5Mpa, and the space velocity is 1.0h -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0052] Example results: C5 + liquid yield is 94.3wt%, the product is cut by actual boiling point, heavy naphtha yield is 57.3wt%, light diesel yield is 17.5wt%, heavy diesel yield is 14.4wt%, and tail oil yield is 5.1wt%.

[0053] Example 4

[0054] (1) Add polyethylene (PE) block waste plastics into an intermittent reactor with a stirring function, add ethylene glycol, flavonoids, and cyclohexane in a mass ratio of 6:2:1 as a composite solvent, and the mass ratio of the composite solvent added to the waste plastics is 8.0. The mass ratio of potassium-based catalyst A1 to the waste plastics is 0.3:1. The reaction pressure is 4.0 MPa, the reaction temperature is 500°C, the reaction time is 0.5 h, the stirring speed is 2000 rpm, and the obtained solid-liquid mixture is solid-liquid separated to obtain liquefied waste plastics.

[0055] (2) Liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 15wt%:85wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B4, with a catalyst filling volume of 200mL, a cracking reaction temperature of 380°C, a reaction pressure of 15.5Mpa, and a space velocity of 1.2h. -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0056] Example results: C5 + liquid yield is 95.1wt%, the product is cut by actual boiling point, heavy naphtha yield is 55.8wt%, light diesel yield is 19.2wt%, heavy diesel yield is 11.4wt%, and tail oil yield is 8.7wt%.

[0057] Example 5

[0058] (1) Add polyethylene (PE) block waste plastics into an intermittent reactor with a stirring function, add n-propanol, acetone, and cyclohexane in a mass ratio of 4.5:2:1 as a composite solvent, and the mass ratio of the composite solvent added to the waste plastics is 8.0. The mass ratio of potassium-based catalyst A2 to the waste plastics is 0.5:1. The reaction pressure is 6.0 MPa, the reaction temperature is 300°C, the reaction time is 2 h, the stirring speed is 2000 rpm, and the obtained solid-liquid mixture is solid-liquid separated to obtain liquefied waste plastics.

[0059] (2) Liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 25wt%:75wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B1, the catalyst filling volume is 200mL, the cracking reaction temperature is 380°C, the reaction pressure is 15.5Mpa, and the space velocity is 0.7h -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0060] Example results: C5 + liquid yield is 95.1wt%, the product is cut by actual boiling point, heavy naphtha yield is 57.3wt%, light diesel yield is 14.5wt%, heavy diesel yield is 16.4wt%, and tail oil yield is 6.9wt%.

[0061] Example 6

[0062] (1) Add polyethylene (PE) block waste plastics into an intermittent reactor with a stirring function, add isoamyl alcohol, acetone, and cyclohexane in a mass ratio of 2.5:1:1 as a composite solvent, and the mass ratio of the composite solvent added to the waste plastics is 5.0. The mass ratio of potassium-based catalyst A3 to the waste plastics is 0.5:1. The reaction pressure is 10.0 MPa, the reaction temperature is 250°C, the reaction time is 6 h, the stirring speed is 2000 rpm, and the obtained solid-liquid mixture is solid-liquid separated to obtain liquefied waste plastics.

[0063] (2) Liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 35wt%:65wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B1, the catalyst filling volume is 200mL, the cracking reaction temperature is 380°C, the reaction pressure is 15.5Mpa, and the space velocity is 0.5h -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0064] Example results: C5 + liquid yield is 93.8wt%, the product is cut by actual boiling point, heavy naphtha yield is 58.8wt%, light diesel yield is 15.5wt%, heavy diesel yield is 11.4wt%, and tail oil yield is 8.1wt%.

[0065] Example 7

[0066] (1) Add polyethylene (PE) block waste plastics into an intermittent reactor with a stirring function, add isoamyl alcohol, acetone, and cyclohexane in a mass ratio of 4:2:1 as a composite solvent, and the mass ratio of the composite solvent added to the waste plastics is 3.0. The mass ratio of potassium-based catalyst A1 to the waste plastics is 0.5:1. The reaction pressure is 10.0 MPa, the reaction temperature is 400°C, the reaction time is 3 h, the stirring speed is 2000 rpm, and the obtained solid-liquid mixture is solid-liquid separated to obtain liquefied waste plastics.

[0067] (2) Liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 35wt%:65wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B1, the catalyst filling volume is 200mL, the cracking reaction temperature is 380°C, the reaction pressure is 15.5Mpa, and the space velocity is 0.5h -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0068] Example results: C5 + liquid yield is 95.7wt%, the product is cut by actual boiling point, heavy naphtha yield is 53.3wt%, light diesel yield is 19.3wt%, heavy diesel yield is 16.1wt%, and tail oil yield is 7.0wt%.

[0069] Example 8

[0070] (1) Add polyethylene (PE) block waste plastics into an intermittent reactor with a stirring function, add isoamyl alcohol, acetone, and cyclohexane in a mass ratio of 4:2:1 as a composite solvent, and the mass ratio of the composite solvent added to the waste plastics is 3.0. The mass ratio of potassium-based catalyst A1 to the waste plastics is 0.3:1. The reaction pressure is 10.0 MPa, the reaction temperature is 400°C, the reaction time is 3 h, the stirring speed is 2000 rpm, and the obtained solid-liquid mixture is solid-liquid separated to obtain liquefied waste plastics.

[0071] (2) Liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 35wt%:65wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B1, the catalyst filling volume is 200mL, the cracking reaction temperature is 380°C, the reaction pressure is 15.5Mpa, and the space velocity is 0.5h -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0072] Example results: C5 + liquid yield is 96.1wt%, the product is cut by actual boiling point, heavy naphtha yield is 53.4wt%, light diesel yield is 20.1wt%, heavy diesel yield is 14.5wt%, and tail oil yield is 8.1wt%.

[0073] Example 9

[0074] (1) Adding polypropylene (PP) block waste plastic into an intermittent reactor with a stirring function, adding ethylene glycol, flavonoids, and cyclohexane in a mass ratio of 6:2:1 as a composite solvent, and the mass ratio of the composite solvent added to the waste plastic is 8.0. The mass ratio of potassium-based catalyst A1 to the waste plastic is 0.3:1. The reaction pressure is 4.0 MPa, the reaction temperature is 500°C, the reaction time is 0.5 h, the stirring speed is 2000 rpm, and the obtained solid-liquid mixture is solid-liquid separated to obtain liquefied waste plastic.

[0075] (2) Liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 15wt%:85wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B1, the catalyst filling volume is 200mL, the cracking reaction temperature is 380°C, the reaction pressure is 15.5Mpa, and the space velocity is 1.0h -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0076] Example results: C5 + liquid yield is 95.5wt%, the product is cut by actual boiling point, heavy naphtha yield is 59.3wt%, light diesel yield is 16.5wt%, heavy diesel yield is 12.4wt%, and tail oil yield is 7.3wt%.

[0077] Example 10

[0078] (1) Add polystyrene (PS) block waste plastic into a batch reactor with a stirring function, add ethylene glycol, flavonoids, and cyclohexane in a mass ratio of 6:2:1 as a composite solvent, and the mass ratio of the composite solvent added to the waste plastic is 8.0. The mass ratio of potassium-based catalyst A1 to the waste plastic is 0.3:1. The reaction pressure is 4.0 MPa, the reaction temperature is 500°C, the reaction time is 0.5 h, the stirring speed is 2000 rpm, and the obtained solid-liquid mixture is solid-liquid separated to obtain liquefied waste plastic.

[0079] (2) Liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 15wt%:85wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B1, the catalyst filling volume is 200mL, the cracking reaction temperature is 380°C, the reaction pressure is 15.5Mpa, and the space velocity is 1.0h -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0080] Example results: C5 + liquid yield is 95.5wt%, the product is cut by actual boiling point, heavy naphtha yield is 59.3wt%, light diesel yield is 16.5wt%, heavy diesel yield is 12.4wt%, and tail oil yield is 7.3wt%.

[0081] Embodiment 11

[0082] (1) Adding polypropylene (PP) block waste plastic into an intermittent reactor with a stirring function, adding ethylene glycol, flavonoids, and cyclohexane in a mass ratio of 6:2:1 as a composite solvent, and the mass ratio of the composite solvent added to the waste plastic is 8.0. The mass ratio of potassium-based catalyst A1 to the waste plastic is 0.3:1. The reaction pressure is 4.0 MPa, the reaction temperature is 500°C, the reaction time is 0.5 h, the stirring speed is 2000 rpm, and the obtained solid-liquid mixture is solid-liquid separated to obtain liquefied waste plastic.

[0083] (2) Liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 15wt%:85wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B2, the catalyst filling volume is 200mL, the cracking reaction temperature is 380°C, the reaction pressure is 15.5Mpa, and the space velocity is 1.0h -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0084] Example results: C5 + liquid yield is 94.5wt%, the product is cut by actual boiling point, heavy naphtha yield is 55.1wt%, light diesel yield is 18.2wt%, heavy diesel yield is 13.4wt%, and tail oil yield is 7.8wt%.

[0085] Example 12

[0086] (1) Adding polypropylene (PP) block waste plastics into an intermittent reactor with a stirring function, adding isobutanol, flavonoids, and cyclohexane in a mass ratio of 6:1.5:1 as a composite solvent, and the mass ratio of the composite solvent added to the waste plastics is 8.0. The mass ratio of potassium-based catalyst A1 to the waste plastics is 0.4:1. The reaction pressure is 4.0 MPa, the reaction temperature is 500°C, the reaction time is 0.5 h, the stirring speed is 2000 rpm, and the obtained solid-liquid mixture is solid-liquid separated to obtain liquefied waste plastics.

[0087] (2) Liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 15wt%:85wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B4, with a catalyst filling volume of 200mL, a cracking reaction temperature of 380°C, a reaction pressure of 15.5Mpa, and a space velocity of 1.2h. -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0088] Example results: C5 + liquid yield is 95.1wt%, the product is cut by actual boiling point, heavy naphtha yield is 55.8wt%, light diesel yield is 19.2wt%, heavy diesel yield is 11.4wt%, and tail oil yield is 8.7wt%.

[0089] Embodiment 13

[0090] (1) Adding polypropylene (PP) block waste plastic into a batch reactor with a stirring function, adding 2-phenylethanol, lignan, and petroleum ether in a mass ratio of 6:0.5:1 as a composite solvent, and the mass ratio of the composite solvent added to the waste plastic is 8.0. The mass ratio of potassium-based catalyst A1 to the waste plastic is 0.4:1. The reaction pressure is 4.0 MPa, the reaction temperature is 500°C, the reaction time is 0.5 h, the stirring speed is 2000 rpm, and the obtained solid-liquid mixture is solid-liquid separated to obtain liquefied waste plastic.

[0091] (2) Liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 15wt%:85wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B4, with a catalyst filling volume of 200mL, a cracking reaction temperature of 380°C, a reaction pressure of 15.5Mpa, and a space velocity of 1.2h. -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0092] Example results: C5 + liquid yield is 95.8wt%, the product is cut by actual boiling point, heavy naphtha yield is 53.1wt%, light diesel yield is 19.2wt%, heavy diesel yield is 11.4wt%, and tail oil yield is 12.1wt%.

[0093] Comparative Example 1

[0094] Wax oil with dry point ≯500℃ as material flow I passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B1. The catalyst filling volume is 200mL, the cracking reaction temperature is 380℃, the reaction pressure is 15.5Mpa, and the space velocity is 1.2h -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0095] Comparative example results: C5+ liquid yield is 96.5wt%, the product is cut by actual boiling point, naphtha yield is 52.4wt%, light diesel yield is 18.2wt%, heavy diesel yield is 7.4wt%, and tail oil yield is 18.5wt%.

[0096] Comparative Example 2

[0097] The difference from Example 1 is that step (1) uses a high-temperature hot melt method to liquefy the waste plastics, specifically:

[0098] (1) Adding polyethylene (PE) block waste plastic into a high-temperature liquefaction reactor, the reaction pressure is 0.3 MPa, the reaction temperature is 600°C, and the reaction time is 1 hour to obtain high-temperature liquefied waste plastic.

[0099] (2) High-temperature liquefied waste plastics are used as material flow I, and wax oil raw materials with a dry point of ≯500°C are used as material flow II. The mixing ratio of material flow I and material flow II is 15wt%:85wt%. The mixed material flow passes through a hydrocracking fixed bed reactor filled with hydrocracking catalyst B1, the catalyst filling volume is 200mL, the cracking reaction temperature is 380°C, the reaction pressure is 15.5Mpa, and the space velocity is 1.0h -1 , hydrogen-to-oil ratio is 1500:1, and a hydrocracking reaction is carried out to obtain a reaction product.

[0100] Comparative example results: C5+ liquid yield is 98.1wt%, the product is cut by actual boiling point, naphtha yield is 50.3wt%, light diesel yield is 20.1wt%, heavy diesel yield is 13.5wt%, and tail oil yield is 14.2wt%.

[0101] It can be seen from the results of the embodiments and comparative examples that, compared with the thermal treatment method of high-temperature hot melting, the method of the present invention improves the yield of naphtha by liquefying waste plastics using a composite solvent and a potassium-based catalyst.

[0102] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for producing more naphtha by mixing and hydrocracking waste plastics, characterized in that: The following steps are involved: (1) adding waste plastics into an intermittent reactor with a stirring function, adding a composite solvent and a potassium-based catalyst, liquefying the waste plastics, and separating a liquid-solid mixture produced by liquefaction to obtain liquefied waste plastics; (2) liquefied waste plastics as material stream I and wax oil raw materials with a dry point of ≯500°C as material stream II are mixed and passed through a fixed bed reactor filled with a hydrocracking catalyst to perform a hydrocracking reaction to obtain a base oil product; Wherein, the composite solvent in step (1) is obtained by mixing solvent I, solvent II and solvent III in a mass ratio of (2.5-6): (0.5-2):

1.

2. The method according to claim 1, characterized in that The solvent I is at least one of ethylene glycol, n-propanol, isobutanol, isopentanol and 2-phenylethanol; the solvent II is at least one of flavonoids, lignans and acetone; and the solvent III is at least one of cyclohexane and petroleum ether.

3. The method according to claim 1, characterized in that In step (1), the composite solvent is obtained by mixing solvent I, solvent II and solvent III in a mass ratio of (4-6): (1.5-2):

1.

4. The method according to claim 1, characterized in that In step (1), the mass ratio of the composite solvent to the waste plastic is (3-8):

1.

5. The method according to claim 1, characterized in that In step (1), the mass ratio of the potassium-based catalyst to the waste plastic is 0.3-0.5:

1.

6. The method according to claim 1, characterized in that In step (1), the waste plastics include at least one of polyethylene (PE), polypropylene (PP), and polystyrene (PS).

7. The method according to claim 1, characterized in that In step (2), the mixing ratio of the material flow I and the material flow II is (15wt%-35wt%): (85wt%-65wt%).

8. The method according to claim 1, characterized in that In step (2), the hydrocracking catalyst comprises the following components: (a) at least one of zirconium oxide, titanium oxide, iron oxide, and potassium oxide; (b) at least one of USY molecular sieve, ZSM-5 molecular sieve, and SBA-16 molecular sieve; (c) amorphous silicon aluminum; and (d) at least one of nickel oxide, tungsten oxide, and phosphoric acid.

9. The method according to claim 1, characterized in that: In step (1), the pressure of the reactor is 4-10 MPa, the temperature is 250-500° C., and the residence time of the waste plastic in the reactor is 0.5-6 h.

10. The method according to claim 1, characterized in that In step (2), the temperature of the hydrocracking reaction is 365-380°C, the reaction pressure is 14-17Mpa, and the space velocity is 0.5-1.2h -1 , hydrogen-oil ratio 700-1500:1.