Method for dechlorinating waste plastic pyrolysis oil

Abstract

The invention discloses a waste plastic pyrolysis oil dechlorination method, which comprises: S1, removing mechanical impurities in waste plastic pyrolysis oil, washing to remove inorganic chloride, carrying out oil-water separation, and drying the obtained oil phase to obtain primary dechlorinated waste plastic pyrolysis oil; s2, the primary dechlorinated waste plastic pyrolysis oil and hydrogen are mixed and then subjected to pre-hydrogenation in a pre-hydrogenation catalytic distillation tower, dialkene is converted into monoolefine, chlorine-rich light pyrolysis oil is obtained at the tower top, chlorine-poor heavy pyrolysis oil is obtained at the tower bottom, and the chlorine-poor heavy pyrolysis oil is rich in sulfur, nitrogen and metal impurities; s3, the chlorine-rich light pyrolysis oil reacts with hydrogen under the action of a hydrodechlorination catalyst to remove organic chlorides, and a reaction product is subjected to gas-liquid separation to obtain hydrodechlorinated pyrolysis oil; and S4, contacting the chlorine-poor heavy pyrolysis oil with an adsorbent to obtain adsorption dechlorinated pyrolysis oil. According to the method, the chlorine removal rate of the waste plastic pyrolysis oil is high, coke is not easy to generate, and the catalyst deactivation is slow.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical recycling of waste plastics, and particularly relates to a method for dechlorinating waste plastic pyrolysis oil. Background Art

[0002] Since the birth of plastics, they have brought about great changes to human production and life and have become an indispensable part of modern society. However, plastics generally have a short lifespan, and the generation of a large amount of waste plastics and their improper disposal have caused serious harm to human health and the ecological environment. To address plastic pollution, countries around the world have successively introduced a series of policies and regulations to encourage and support the recycling and reuse of plastics. Currently, the recycling method of waste plastics mainly relies on physical methods, which mainly deal with waste plastics with relatively single and relatively clean materials. For low-value mixed waste plastics that cannot be disposed of by physical recycling, chemical recycling is not only one of the effective ways to realize the resource utilization of plastic waste but also an important means to solve plastic pollution, and it has a significant carbon emission reduction effect compared with incineration. Among many waste plastic chemical recycling technologies, the technical route of "waste plastic pyrolysis + refining enterprises processing pyrolysis oil" is commonly adopted by domestic and foreign enterprises at present. However, due to the complexity of the composition of waste plastics and the deficiencies of existing sorting technologies in terms of accuracy and efficiency, the properties of plastic pyrolysis oil are generally poor, and the impurity content is much higher than that of crude oil and its fraction oils. It cannot be directly used as the raw material of existing refining units, and the pretreatment of waste plastic pyrolysis oil has become an essential link to realize the industrialization of this technical route. Among them, the removal of chlorine elements in waste plastic pyrolysis oil is the most critical. These chlorine elements mainly come from chlorine-containing plastics such as PVC and halogen-containing plastic additives, and mainly exist in the form of organic chlorine in the pyrolysis oil, with the content generally ranging from several hundred to several thousand ppm, much higher than the design limit of existing refining units. If this untreated pyrolysis oil directly enters the refinery, it is extremely easy to cause equipment corrosion and catalyst poisoning, posing a huge hidden danger to the safe and stable operation of existing refining units. In existing oil dechlorination technologies, the adsorption method has a simple process, but due to the extremely high chlorine content in pyrolysis oil, the adsorbent is easily saturated and difficult to regenerate, and frequent replacement will increase the dechlorination cost; the hydrodechlorination method has a relatively high dechlorination efficiency, but there are competitive reactions between impurities such as metals, sulfur, and nitrogen and chlorides on the catalyst surface, which is not conducive to the removal of chlorides; the large amount of sulfides contained in the pyrolysis products restricts the use of precious metal catalysts with relatively high dechlorination efficiency. In addition, the degree of unsaturation of waste plastic pyrolysis oil is relatively high, and a large amount of dienes in the pyrolysis oil are prone to cause serious coking of equipment such as heating furnaces and heat exchangers, and greatly affect the use activity and lifespan of catalysts. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for dechlorinating waste plastic pyrolysis oil. The method of the present invention has a high chlorine removal rate for waste plastic pyrolysis oil, low investment and operating costs, and effectively avoids the deficiencies of easy coking, fast catalyst deactivation, and high dechlorination cost during the direct hydrodechlorination reaction of waste plastic pyrolysis oil.

[0004] To achieve the above object, the present invention provides a method for dechlorinating waste plastic pyrolysis oil, which is characterized by comprising the following steps:

[0005] S1, after removing mechanical impurities from the waste plastic pyrolysis oil, washing with water to remove inorganic chlorides, and then performing oil-water separation, the obtained oil phase is dried to obtain primary dechlorinated waste plastic pyrolysis oil;

[0006] S2, mixing the primary dechlorinated waste plastic pyrolysis oil with hydrogen and performing pre-hydrogenation in a pre-hydrogenation catalytic distillation column to convert dienes into monoolefins. The chlorine-rich light pyrolysis oil is obtained at the top of the column, and the chlorine-poor heavy pyrolysis oil is obtained at the bottom of the column. The chlorine-poor heavy pyrolysis oil is rich in sulfur, nitrogen, and metal impurities;

[0007] S3, reacting the chlorine-rich light pyrolysis oil with hydrogen under the action of a hydrodechlorination catalyst to remove organic chlorides, and the reaction product is subjected to gas-liquid separation to obtain hydrodechlorinated pyrolysis oil;

[0008] S4, contacting the chlorine-poor heavy pyrolysis oil with an adsorbent to obtain adsorption dechlorinated pyrolysis oil.

[0009] In the method for dechlorinating waste plastic pyrolysis oil of the present invention, the total chlorine content of the waste plastic pyrolysis oil is not less than 100 ppm.

[0010] In the method for dechlorinating waste plastic pyrolysis oil of the present invention, the inorganic chlorine content in the primary dechlorinated waste plastic pyrolysis oil is not more than 5 ppm, and the water content is not more than 500 ppm.

[0011] In the method for dechlorinating waste plastic pyrolysis oil of the present invention, pre-hydrogenation catalysts with gradually decreasing reaction activity are filled from top to bottom in the pre-hydrogenation catalytic distillation column to match the temperature gradient in the distillation column.

[0012] In the method for dechlorinating waste plastic pyrolysis oil of the present invention, the pre-hydrogenation catalyst is composed of alumina and one or more oxides of Co, Mo, Ni, and W.

[0013] In the method for dechlorinating waste plastic pyrolysis oil of the present invention, the mass content of alumina in the pre-hydrogenation catalyst is 70% - 90%, and the content of one or more oxides of Co, Mo, Ni, and W is 10% - 30%.

[0014] In the method for dechlorinating waste plastic pyrolysis oil of the present invention, the pre-hydrogenation catalyst is a structured catalyst.

[0015] In the method for dechlorinating waste plastic pyrolysis oil of the present invention, the reaction temperature of the pre-hydrogenation catalytic distillation column is 90 - 230 °C, the pressure is 0.5 - 5 MPa, the volume space velocity is 2 - 5 h -1 , and the hydrogen-oil volume ratio is 5 - 100:1.

[0016] The method for dechlorination of waste plastic pyrolysis oil according to the present invention, wherein the hydrodechlorination catalyst comprises alumina, magnesium or phosphorus modified alumina, molecular sieve, nickel oxide or cobalt oxide, molybdenum oxide or tungsten oxide, zinc oxide or calcium oxide.

[0017] The method for dechlorination of waste plastic pyrolysis oil according to the present invention, wherein the molecular sieve is one or more of modified Y molecular sieve, modified ZSM-5 molecular sieve and modified 13X molecular sieve. The modification in the present invention is acid modification or hydrothermal modification, etc., which are all common modification methods in the technical field of hydrodechlorination catalysts. The present invention does not make specific limitations, and those skilled in the art can choose according to the actual situation.

[0018] The method for dechlorination of waste plastic pyrolysis oil according to the present invention, wherein the mass composition of the hydrodechlorination catalyst is: 20-30% alumina, 10-30% magnesium or phosphorus modified alumina, 0.5-8% molecular sieve, 2-5% nickel oxide or cobalt oxide, 5-20% molybdenum oxide or tungsten oxide, 7-65% zinc oxide or calcium oxide.

[0019] The method for dechlorination of waste plastic pyrolysis oil according to the present invention, wherein the Na2O content in the molecular sieve is less than 0.5%.

[0020] The method for dechlorination of waste plastic pyrolysis oil according to the present invention, wherein the reaction conditions for hydrodechlorination in step S3 are: reaction temperature 200-360 °C, hydrogen partial pressure 3.5-9 MPa, volume space velocity 0.5-2.5 h -1 , and hydrogen-oil volume ratio 300-700:1.

[0021] The method for dechlorination of waste plastic pyrolysis oil according to the present invention, wherein the adsorbent comprises a carrier composed of one or more of modified 13X molecular sieve, NaY molecular sieve, alumina and activated carbon, and a metal oxide supported on the carrier. The modification in the present invention is acid modification or hydrothermal modification, etc., which are all common modification methods in the technical field of adsorption dechlorination catalysts. The present invention does not make specific limitations, and those skilled in the art can choose according to the actual situation.

[0022] The method for dechlorination of waste plastic pyrolysis oil according to the present invention, wherein the metal oxide in the adsorbent comprises one or more of copper oxide, iron(III) oxide, magnesium oxide, nickel oxide, cobalt oxide, zinc oxide and calcium oxide

[0023] The method for dechlorination of waste plastic pyrolysis oil according to the present invention, wherein the mass content of the carrier in the adsorbent is 75-90%, and the mass content of the metal oxide is 10-25%.

[0024] The method for dechlorination of waste plastic pyrolysis oil according to the present invention, wherein the reaction temperature in step S4 is 50-200 °C, and the volume space velocity is 0.5-1.0 h -1, the reaction pressure is 0.1 to 0.8 MPa.

[0025] In the method for dechlorinating waste plastic pyrolysis oil of the present invention, the hydrodechlorinated pyrolysis oil obtained is used as a raw material for steam cracking or catalytic reforming after deep hydrorefining; the adsorption dechlorinated pyrolysis oil obtained is used as a raw material for atmospheric and vacuum distillation, hydrocracking, fluid catalytic cracking or delayed coking in a refinery.

[0026] Advantages of the present invention:

[0027] Since the organic chlorine in waste plastic pyrolysis oil is mainly concentrated in the light fractions, and the content of organic chlorine in the heavy fractions is very low, while metal impurities such as iron and calcium are mainly enriched in the heavy fractions. In addition, the contents of impurities such as sulfur and nitrogen in the heavy fractions are also higher than those in the light fractions. If the whole fraction of waste plastic pyrolysis oil is directly subjected to hydrodechlorination, the macromolecular hydrocarbons and sulfur and nitrogen compounds in the middle and heavy fractions will compete with small molecule chlorides for adsorption, affecting the removal effect of organic chlorine. At the same time, the polycyclic aromatic hydrocarbons and metal impurities in the heavy fractions are likely to cover or poison the active sites of the hydrodechlorination catalyst, reducing the catalyst activity. Before removing organic chlorine, the waste plastic pyrolysis oil is cut into light and heavy fractions according to the distribution of chlorine elements in the pyrolysis oil. For the light fractions with high organic chlorine content, the hydrodechlorination method is adopted, and for the heavy fractions with low organic chlorine content, the adsorption dechlorination method is adopted. Therefore, the application of the technical solution of the present invention can, on the one hand, avoid the influence of heavy fraction oil molecules on the catalyst activity and service life during the hydrodechlorination of the whole fraction, and on the other hand, only hydrodechlorinate the light fractions and adopt the adsorption dechlorination method for the heavy fraction oil with relatively low organic chlorine content, which can improve the overall removal efficiency of organic chlorine and reduce the operation cost.

[0028] While fractionating, the pre-hydrogenation catalytic distillation column can match pre-hydrogenation catalysts with different activities according to the temperature gradient in the catalytic distillation column, selectively remove diolefins in the light components, reduce the diolefin content in the chlorine-rich light pyrolysis oil, effectively avoid the condensation of diolefins, reduce the generation of coke, which is beneficial to reducing the coverage of the active sites of the catalyst by coke during hydrodechlorination and prolonging the service life of the hydrodechlorination catalyst. At the same time, it is also beneficial to reduce the coking rate of the heating furnace and heat exchanger. In addition, integrating the pre-hydrogenation reactor and the fractionation column into a pre-hydrogenation catalytic distillation column can effectively save equipment investment. Specific embodiments

[0029] The present invention will be specifically described below through examples. It is necessary to point out here that the following examples are only used to further illustrate the present invention and should not be construed as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention according to the above content of the present invention.

[0030] In the embodiments of the present invention, the properties of the waste plastic pyrolysis oil raw material are shown in Table 1.

[0031] Table 1 Properties of the pyrolysis oil raw material

[0032]

[0033]

[0034] After filtering the waste plastic pyrolysis oil raw material to remove mechanical impurities, washing with water to remove inorganic chlorides in the oil product, then performing oil-water separation in a separation tank, and subjecting the separated oil product to adsorption drying treatment in a drying tower, a first-stage dechlorinated waste plastic pyrolysis oil is obtained; after mixing the obtained first-stage dechlorinated waste plastic pyrolysis oil with hydrogen and entering a pre-hydrogenation catalytic distillation column, reacting with hydrogen under the action of a pre-hydrogenation catalyst, determining the cutting temperature according to the chlorine element distribution of the waste plastic pyrolysis oil raw material, and obtaining a chlorine-rich light pyrolysis oil and a chlorine-poor heavy pyrolysis oil; further reacting the chlorine-rich light pyrolysis oil with hydrogen under the action of a hydrodechlorination catalyst to remove organic chlorides, obtaining a hydrodechlorinated pyrolysis oil; and further contacting the chlorine-poor heavy pyrolysis oil with an adsorbent to obtain an adsorption dechlorinated pyrolysis oil.

[0035] Example 1:

[0036] The pre-hydrogenation catalyst A is installed in the upper part of the catalytic distillation column, with a volume ratio of 45%, and the catalyst composition is: 80% alumina, 14% nickel oxide, 6% molybdenum oxide; the pre-hydrogenation catalyst B is installed in the lower part of the catalytic distillation column, with a volume ratio of 45%, and the catalyst composition is: 88% alumina, 8% nickel oxide, 4% molybdenum oxide. Both the pre-hydrogenation catalyst A and the pre-hydrogenation catalyst B are honeycomb-shaped regular catalysts.

[0037] Pre-hydrogenation reaction process conditions: reaction temperature 180 - 195 °C, pressure 2.5 MPa, volume space velocity 2.0 h -1 , hydrogen-oil ratio 100:1 (V:V).

[0038] The cutting point of the light and heavy pyrolysis oils is 160 °C.

[0039] The mass composition of the hydrodechlorination catalyst is: 28% alumina, 30% phosphorus-modified alumina, 4% hydrothermally modified ZSM-5 molecular sieve (containing 0.4% Na2O), 4.5% cobalt oxide, 15.5% molybdenum oxide, 18% zinc oxide.

[0040] Hydrodechlorination reaction process conditions: reaction temperature 290 °C, hydrogen partial pressure 7 MPa, volume space velocity 1 h -1 , hydrogen-oil ratio 500:1 (V:V).

[0041] The mass composition of the adsorption dechlorination catalyst is: 75% acid-modified 13X molecular sieve, 15% alumina, 5% magnesium oxide, 5% iron oxide.

[0042] The process conditions for the adsorption dechlorination reaction are as follows: the reaction temperature is 60 °C, and the space velocity is 0.6 h -1 , and the reaction pressure is 0.8 MPa.

[0043] Example 2:

[0044] The composition of the pre-hydrogenation catalyst is: 80% alumina, 16% nickel oxide, 4% cobalt oxide, and it is a honeycomb-shaped regular catalyst.

[0045] The process conditions for the pre-hydrogenation reaction are: the reaction temperature is 145 - 155 °C, the pressure is 0.8 MPa, and the space velocity is 5.0 h -1 , and the hydrogen-oil ratio is 10:1 (V:V).

[0046] The cut-off point between light and heavy pyrolysis oil is 117 °C.

[0047] The mass composition of the hydrodechlorination catalyst is: 20% alumina, 10% phosphorus-modified alumina, 0.5% acid-modified Y zeolite, 3% cobalt oxide, 5% molybdenum oxide, and 61.5% zinc oxide.

[0048] The process conditions for the hydrodechlorination reaction are: the reaction temperature is 210 °C, the hydrogen partial pressure is 4 MPa, and the space velocity is 2.5 h -1 , and the hydrogen-oil ratio is 350:1 (V:V).

[0049] The mass composition of the adsorption dechlorination catalyst is: 88% activated carbon, 2% copper oxide, and 10% calcium oxide.

[0050] The process conditions for the adsorption dechlorination reaction are: the reaction temperature is 150 °C, and the space velocity is 0.8 h -1 , and the reaction pressure is 0.5 MPa.

[0051] Example 3:

[0052] The composition of the pre-hydrogenation catalyst is: 70% alumina, 16% nickel oxide, and 14% molybdenum oxide.

[0053] The process conditions for the pre-hydrogenation reaction are: the reaction temperature is 215 - 228 °C, the pressure is 4.8 MPa, and the space velocity is 3.0 h -1 , and the hydrogen-oil ratio is 50:1 (V:V).

[0054] The cut-off point between light and heavy pyrolysis oil is 210 °C.

[0055] The mass composition of the hydrodechlorination catalyst is: 30% alumina, 15% magnesium-modified alumina, 8% hydrothermally modified 13X zeolite, 5% nickel oxide, 20% tungsten oxide, and 22% calcium oxide.

[0056] The process conditions for the hydrodechlorination reaction are: the reaction temperature is 360 °C, the hydrogen partial pressure is 9 MPa, and the space velocity is 0.5 h-1 , the hydrogen-oil ratio is 700:1 (V:V).

[0057] The mass composition of the adsorption dechlorination catalyst is: 90% alumina, 5% nickel oxide, and 5% cobalt oxide.

[0058] The process conditions for the adsorption dechlorination reaction are: reaction temperature 200 °C, volume space velocity 1 h -1 , and the reaction pressure is 0.3 MPa.

[0059] The properties of the light chlorine-rich pyrolysis oil, heavy chlorine-poor pyrolysis oil, and dechlorinated pyrolysis oil are shown in Table 2.

[0060] Table 2 Properties of the primary dechlorinated waste plastic pyrolysis oil, light chlorine-rich pyrolysis oil, heavy chlorine-poor pyrolysis oil, and dechlorinated pyrolysis oil

[0061]

[0062]

[0063] Comparative Example 1:

[0064] The waste plastic pyrolysis oil raw material 1 was subjected to the same water washing, separation, and drying processes as in the examples to obtain the waste plastic pyrolysis oil with inorganic chlorine removed; the obtained waste plastic pyrolysis oil was directly subjected to hydrodechlorination without pre-hydrogenation reaction and fractionation, and the hydrodechlorination conditions were the same as in Example 1 to obtain the waste plastic pyrolysis oil with organic chlorine removed, and the properties are shown in Table 3.

[0065] Comparative Example 2:

[0066] The waste plastic pyrolysis oil raw material 2 was subjected to the same water washing, separation, and drying processes as in the examples to obtain the waste plastic pyrolysis oil with inorganic chlorine removed; the obtained waste plastic pyrolysis oil was directly subjected to adsorption dechlorination without pre-hydrogenation reaction and fractionation, and the adsorption dechlorination conditions were the same as in Example 2 to obtain the waste plastic pyrolysis oil with organic chlorine removed, and the properties are shown in Table 3.

[0067] Comparative Example 3:

[0068] The waste plastic pyrolysis oil raw material 3 was subjected to the same water washing, separation, and drying processes as in the examples to obtain the waste plastic pyrolysis oil with inorganic chlorine removed; the obtained waste plastic pyrolysis oil was not subjected to pre-hydrogenation reaction, but only cut into light and heavy components according to the same ratio as in Example 3, and the light and heavy components were respectively subjected to hydrodechlorination and adsorption dechlorination processes, and the hydrodechlorination and adsorption dechlorination conditions were the same as in Example 3 to obtain the light and heavy waste plastic pyrolysis oils with organic chlorine removed, and the properties are shown in Table 3.

[0069] Table 3 Properties of the dechlorinated pyrolysis oil of the comparative examples of the present invention

[0070] Project Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 3 Full fraction Full fraction Light fraction Heavy fraction Total chlorine, mg / kg 128 97 23 9

[0071] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention. However, these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for dechlorination of waste plastic pyrolysis oil, characterized in that, it comprises the following steps: S1, after removing mechanical impurities from the waste plastic pyrolysis oil, washing with water to remove inorganic chlorides, and then performing oil-water separation, the obtained oil phase is dried to obtain primary dechlorinated waste plastic pyrolysis oil; S2, mixing the primary dechlorinated waste plastic pyrolysis oil with hydrogen and performing pre-hydrogenation in a pre-hydrogenation catalytic distillation column to convert dienes into monoolefins. Rich-chlorine light pyrolysis oil is obtained at the top of the column, and poor-chlorine heavy pyrolysis oil is obtained at the bottom of the column. The poor-chlorine heavy pyrolysis oil is rich in sulfur, nitrogen, and metal impurities; S3, reacting the rich-chlorine light pyrolysis oil with hydrogen under the action of a hydrodechlorination catalyst to remove organic chlorides, and the reaction product is subjected to gas-liquid separation to obtain hydrodechlorinated pyrolysis oil; S4, contacting the poor-chlorine heavy pyrolysis oil with an adsorbent to obtain adsorption dechlorinated pyrolysis oil.

2. The method for dechlorination of waste plastic pyrolysis oil according to claim 1, characterized in that, the total chlorine content of the waste plastic pyrolysis oil is not less than 100 ppm.

3. The method for dechlorination of waste plastic pyrolysis oil according to claim 1, characterized in that, the inorganic chlorine content in the primary dechlorinated waste plastic pyrolysis oil is not more than 5 ppm, and the water content is not more than 500 ppm.

4. The method for dechlorination of waste plastic pyrolysis oil according to claim 1, characterized in that, pre-hydrogenation catalysts with gradually decreasing reaction activity are filled from top to bottom in the pre-hydrogenation catalytic distillation column to match the temperature gradient in the distillation column.

5. The method for dechlorination of waste plastic pyrolysis oil according to claim 4, characterized in that, the pre-hydrogenation catalyst is composed of alumina and one or more oxides of Co, Mo, Ni, and W.

6. The method for dechlorination of waste plastic pyrolysis oil according to claim 4, characterized in that, the mass content of alumina in the pre-hydrogenation catalyst is 70% - 90%, and the content of one or more oxides of Co, Mo, Ni, and W is 10% - 30%.

7. The method for dechlorination of waste plastic pyrolysis oil according to claim 4, characterized in that, the pre-hydrogenation catalyst is a structured catalyst.

8. The method for dechlorination of waste plastic pyrolysis oil according to claim 1, characterized in that, The reaction temperature of the pre-hydrogenation catalytic distillation column is 90 to 230 °C, the pressure is 0.5 to 5 MPa, the volume space velocity is 2 to 5 h -1 , and the hydrogen-oil volume ratio is 5 to 100:

1.

9. The method for dechlorination of waste plastic pyrolysis oil according to claim 1, characterized in that, the hydrodechlorination catalyst includes alumina, magnesium or phosphorus modified alumina, molecular sieve, nickel oxide or cobalt oxide, molybdenum oxide or tungsten oxide, zinc oxide or calcium oxide.

10. The method for dechlorination of waste plastic pyrolysis oil according to claim 9, characterized in that, the molecular sieve is one or more of modified Y molecular sieve, modified ZSM-5 molecular sieve, and modified 13X molecular sieve.

11. The method for dechlorination of waste plastic pyrolysis oil according to claim 9, characterized in that, the mass composition of the hydrodechlorination catalyst is: 20 - 30% alumina, 10 - 30% magnesium or phosphorus modified alumina, 0.5 - 8% molecular sieve, 2 - 5% nickel oxide or cobalt oxide, 5 - 20% molybdenum oxide or tungsten oxide, 7 - 65% zinc oxide or calcium oxide.

12. The method for dechlorination of waste plastic pyrolysis oil according to claim 9, characterized in that, The Na2O content in the molecular sieve is less than 0.5%.

13. The method for dechlorination of waste plastic pyrolysis oil according to claim 9, characterized in that, The hydrodechlorination reaction conditions in step S3 are as follows: reaction temperature is 200 - 360 °C, hydrogen partial pressure is 3.5 - 9 MPa, volumetric space velocity is 0.5 - 2.5 h -1 , and hydrogen - to - oil volume ratio is 300 - 700:

1.

14. The method for dechlorination of waste plastic pyrolysis oil according to claim 1, characterized in that, the adsorbent comprises a carrier composed of one or more of modified 13X molecular sieve, NaY molecular sieve, alumina and activated carbon, and a metal oxide supported on the carrier.

15. The method for dechlorination of waste plastic pyrolysis oil according to claim 14, characterized in that, the metal oxide in the adsorbent comprises one or more of copper oxide, ferric oxide, magnesium oxide, nickel oxide, cobalt oxide, zinc oxide and calcium oxide.

16. The method for dechlorination of waste plastic pyrolysis oil according to claim 14, characterized in that, the mass content of the carrier in the adsorbent is 75-90%, and the mass content of the metal oxide is 10-25%.

17. The method for dechlorination of waste plastic pyrolysis oil according to claim 1, characterized in that, The reaction temperature in step S4 is 50 to 200 °C, the volume space velocity is 0.5 to 1.0 h -1 , and the reaction pressure is 0.1 to 0.8 MPa.

Images