A method of treating a chlorinated plastic oil

Abstract

The present application relates to the field of waste plastic oil recycling, and discloses a method for treating plastic oil containing chlorine. The method comprises the following steps: contacting the plastic oil containing chlorine with sodium methoxide and H2O2 to perform a first reaction, then contacting the obtained reaction product with water and a demulsifier to perform mixing, and then performing first oil-water separation on the obtained mixture to obtain an oil phase; in the presence of a palladium-carbon catalyst, contacting the oil phase with a hydrogen donor and lye, and blowing in H2 to perform a second reaction, and then performing second oil-water separation on the obtained reaction product. The method for treating plastic oil containing chlorine can ensure the dechlorination effect, solve the problem of high cost of catalytic hydrogenation dechlorination, improve the safety of operation, and does not require additional high-temperature and high-pressure hydrogenation devices and dechlorination devices, and in the preferred case, low-temperature and low-pressure operation is adopted, and the reaction conditions are more moderate.

Description

Technical Field

[0001] This invention relates to the field of waste plastic oil recycling, and specifically to a method for treating chlorine-containing plastic oil. Background Technology

[0002] Common waste plastics include: polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), polymethyl methacrylate (PMMA), polycarbonate (PC), polylactic acid (PA), nylon, fiberglass (FRP), and polylactic acid film (BOPLA).

[0003] Waste plastics can be converted into recycled oil, known as plastic oil or waste plastic oil, under high temperatures or with a catalyst. Plastic oil can be used as fuel or a chemical feedstock, or, under appropriate processing conditions, it can be converted into high-value-added products such as diesel, low-carbon olefins, and high-octane gasoline. Preparing plastic oil from waste plastics and then using it as a raw material to manufacture high-value-added products represents a promising technology for the chemical recycling of waste plastics, attracting widespread attention both domestically and internationally.

[0004] Methods for pyrolysis and oilification of waste plastics include thermal pyrolysis, catalytic pyrolysis, thermal pyrolysis-catalytic reforming, and catalytic pyrolysis-catalytic reforming. The catalysts used include solid acid catalysts, alkali metal catalysts (such as CaO, BaO, Al2O3), and molecular sieves (ZSM-5).

[0005] Because there are many types of waste plastics and they contain a variety of additives, the impurity content in plastic oil is generally high, with the main impurities including chlorine and metals.

[0006] Chlorine in plastic oils has a significant impact on subsequent processing. The chlorine in plastic oils mainly comes from HCl released during the decomposition of PVC. Literature reports that PVC begins dechlorination at 200℃ and completes dechlorination before 350℃. HCl can add to other olefins or alkynes produced during cracking to form chlorinated alkanes or chlorinated olefins. HCl can also react with PET decomposition products to form chlorinated esters. These chlorinated hydrocarbons and esters release HCl again during plastic oil processing, causing equipment corrosion and salt formation. Therefore, many plastic oil companies have strict requirements on the PVC and PET content of waste plastic raw materials. However, due to the wide availability of waste plastics and the difficulty of sorting them, the actual plastic oils produced still have excessive chlorine content. For example, some companies produce plastic oils with a chlorine content of 0.25%-0.48%, which has a significant impact on subsequent processing, leading to equipment corrosion and catalyst poisoning.

[0007] Currently, the main methods for removing organochlorines include catalytic hydrogenation, advanced oxidation, metal reduction, nucleophilic substitution, electrochemical dechlorination, and biological dechlorination. Among these methods, catalytic hydrogenation has the highest dechlorination efficiency (greater than 90%), while other methods have relatively low chlorine removal rates (less than 40%).

[0008] Catalytic hydrogenation involves the reaction of hydrogen with organic chlorides on the surface of a catalyst to produce HCl and the corresponding hydrocarbons. CN104492480A and CN111171865A disclose methods for catalytic hydrodechlorination, but these methods require reaction temperatures exceeding 300℃ and reaction pressures exceeding 2.5 MPa, necessitating high-temperature, high-pressure equipment, resulting in high equipment investment and operating costs. Furthermore, the HCl produced during catalytic hydrodechlorination can cause equipment corrosion, seriously affecting operational safety.

[0009] Although CN1800310A and CN1095388A disclose a dechlorinating agent for catalytic reforming regenerated gas and its preparation method, the dechlorinating agent contains the following chemical raw materials in the following mass percentages: Ca(OH)2 or CaO 30%-60%, MgCO3 or MgO 20%-30%, K2CO3 or KOH 10%-15%, porous zeolite or silica-alumina clay 5%-15%, and alumina powder or silica sol 5%-15%, with the total amount of raw materials being 100%. However, even with the addition of the dechlorinating agent during catalytic hydrodechlorination, 100% removal of the generated HCl cannot be guaranteed, thus compromising operational safety.

[0010] Although catalytic hydrogenation can efficiently remove organochlorine compounds, it has two main drawbacks: high equipment investment and operating costs, and the inability to address the safety issues caused by HCl corrosion under high temperature and pressure. Summary of the Invention

[0011] The purpose of this invention is to overcome the problems of existing organochlorine removal methods, such as the need for improved dechlorination efficiency, the requirement for additional hydrogenation and dechlorination devices, high cost, and poor safety.

[0012] To achieve the above objectives, the present invention provides a method for treating chlorinated plastic oil, the method comprising the following steps:

[0013] (1) Chlorinated plastic oil is contacted with sodium methoxide and H2O2 to carry out a first reaction, and then the resulting reaction product is contacted with water and demulsifier to mix. The resulting mixture is then subjected to a first oil-water separation to obtain the oil phase.

[0014] (2) In the presence of a palladium-carbon catalyst, the oil phase is contacted with a hydrogen donor and an alkaline solution, and H2 is bubbled in to carry out a second reaction. The resulting reaction product is then subjected to a second oil-water separation.

[0015] Through the above technical solution, the method provided by the present invention for treating chlorinated plastic oil can solve the problem of high cost of catalytic hydrodechlorination while ensuring the dechlorination effect, and improve the safety of operation. It does not require additional hydrogenation and dechlorination devices, and in preferred cases, it adopts low temperature and low pressure operation, making the reaction conditions more mild. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] In this invention, unless otherwise stated, room temperature means 25±2°C.

[0018] In this invention, unless otherwise stated, all pressures are gauge pressures.

[0019] In this invention, unless otherwise stated, the atmospheric pressure is expressed as 0.1013 MPa.

[0020] As mentioned above, the present invention provides a method for treating chlorinated plastic oil, the method comprising the following steps:

[0021] (1) Chlorinated plastic oil is contacted with sodium methoxide and H2O2 to carry out a first reaction, and then the resulting reaction product is contacted with water and demulsifier to mix. The resulting mixture is then subjected to a first oil-water separation to obtain the oil phase.

[0022] (2) In the presence of a palladium-carbon catalyst, the oil phase is contacted with a hydrogen donor and an alkaline solution, and H2 is bubbled in to carry out a second reaction. The resulting reaction product is then subjected to a second oil-water separation.

[0023] According to some embodiments of the present invention, preferably, in step (1), the sodium methoxide is provided in the form of a sodium methoxide methanol solution. Preferably, in the sodium methoxide methanol solution, the mass ratio of sodium methoxide to methanol is 0.5-1.5:1, more preferably 0.8-1.2:1.

[0024] According to some embodiments of the present invention, preferably, in step (1), the mass ratio of sodium methoxide to H2O2 is 1-10:1, more preferably 2.5-5:1.

[0025] According to some embodiments of the present invention, preferably, in step (1), the mass ratio of the chlorinated plastic oil to the sodium methoxide is 100:0.1-15, more preferably 100:2.5-10.

[0026] According to some embodiments of the present invention, preferably, in step (1), the conditions of the first reaction include: a reaction temperature of 70-120°C, preferably 80-110°C; and a reaction time of 1-5 h, preferably 1-3 h.

[0027] According to some embodiments of the present invention, preferably, in step (1), after the first reaction, the obtained reaction product is cooled down and then mixed with water and demulsifier.

[0028] According to some embodiments of the present invention, preferably, in step (1), the mass ratio of the water to the chlorinated plastic oil is 1-2:1, more preferably 1-1.5:1.

[0029] According to some embodiments of the present invention, preferably, in step (1), the demulsifier is at least one of fatty alcohol polyoxypropylene polyoxyethylene ether, polyol polyoxypropylene polyoxyethylene ether, polyethylene polyamine polyoxypropylene polyoxyethylene ether, alkylphenol polyoxypropylene polyoxyethylene ether, and alkylphenol amine polyoxypropylene polyoxyethylene ether.

[0030] According to some embodiments of the present invention, preferably, in step (1), the amount of the demulsifier used is 50-200 μg, more preferably 100-150 μg, relative to 1g of the chlorine-containing plastic oil.

[0031] According to some embodiments of the present invention, preferably, in step (1), the first oil-water separation method is centrifugal separation, and the conditions for centrifugal separation include: centrifugal speed of 1500-2000 rpm and centrifugal time of 5-20 min.

[0032] According to some embodiments of the present invention, preferably, in step (2), the content of Pd in ​​the palladium-on-carbon catalyst is 5-20 wt%, more preferably 7-15 wt%.

[0033] According to some embodiments of the present invention, preferably, in step (2), the method for preparing the palladium-carbon catalyst includes: impregnating activated carbon with an aqueous solution of palladium chloride salt, and then reducing the obtained impregnated product by contacting it with KBH4.

[0034] Preferably, before the impregnation, the activated carbon is further subjected to an acidification treatment. The acidification treatment includes mixing the activated carbon with an aqueous solution of HNO3.

[0035] Preferably, the method further includes: washing the product obtained from the acidification treatment with deionized water until neutral, and drying the washed product to remove residual moisture. The washing and drying operations and conditions can be performed with reference to existing technology, and there are no particular limitations thereto.

[0036] According to some embodiments of the present invention, preferably, the acidification treatment conditions include: a temperature of 30-50°C and a time of 1-5 hours.

[0037] According to some embodiments of the present invention, preferably, the impregnation conditions include: a temperature of 40-60°C and a time of 1-2 hours.

[0038] According to some embodiments of the present invention, preferably, the obtained impregnation product is first cooled to room temperature before being contacted with KBH4. Preferably, the contact method includes: placing the cooled impregnation product in an ice-water bath, adding an aqueous solution of KBH4 dropwise while stirring, controlling the dropping rate to maintain the system temperature at the reduction temperature, and adding until no more bubbles are generated.

[0039] According to some embodiments of the present invention, preferably, the reduction temperature is 0℃±1℃.

[0040] According to some embodiments of the present invention, preferably, after the reduction is completed, the obtained reduction product is further subjected to filtration, washing, and drying in sequence. The filtration, washing, and drying operations and conditions can be performed with reference to the prior art, and there are no particular limitations thereto.

[0041] According to some embodiments of the present invention, preferably, in step (2), the mass ratio of the oil phase to the palladium-carbon catalyst is 120:1-2.

[0042] According to some embodiments of the present invention, preferably, in step (2), the hydrogen donor is at least one of formate, phosphite, hydrazine, alcohol and metal hydride.

[0043] According to some embodiments of the present invention, preferably, in step (2), the mass ratio of the oil phase to the hydrogen donor is 120:0.1-5, more preferably 120:0.2-2.

[0044] According to some embodiments of the present invention, preferably, in step (2), the alkaline solution is an aqueous solution of NaOH, and the concentration of the alkaline solution is 0.1-2 wt%, preferably 0.2-1 wt%.

[0045] According to some embodiments of the present invention, preferably, in step (2), the mass ratio of the oil phase to the alkaline solution is 1:0.5-1.5.

[0046] According to some embodiments of the present invention, in step (2), H2 is bubbled in during the reaction process, preferably at a flow rate of 5-15 mL / min.

[0047] According to some embodiments of the present invention, preferably, in step (2), the conditions of the second reaction include: a reaction temperature of 70-150°C, preferably 70-130°C; a reaction time of 0.5-5h, preferably 1-3h; and a reaction pressure of less than 1MPa, preferably atmospheric pressure to 0.8MPa.

[0048] According to some embodiments of the present invention, preferably, the chlorine content of the chlorine-containing plastic oil is 200-4000 μg / g.

[0049] The present invention will be described in detail below through embodiments.

[0050] In the following examples and comparative examples, unless otherwise specified, all raw materials used are commercially available products. Among them:

[0051] Activated carbon was purchased from Sinopharm Group, 80-100 mesh;

[0052] The PdCl2 solution was purchased from Suzhou Jinwo Chemical Co., Ltd., with Pd ≥ 59.5 wt%.

[0053] Demulsifier, purchased from Beijing Linhua Water Stabilizer Factory, model RP-2;

[0054] 98wt% hydrazine hydrate, Inokai reagent;

[0055] The properties of chlorinated plastic oils are shown in Table 1, and the composition of their chlorinated compounds is shown in Table 2.

[0056] Table 1

[0057] <![CDATA[Density (20°C) / (kg / m 3 )]]> 863.4 811.2 Oxygen mass fraction / % 3.4 3.68 Fe / (μg / g) 9.3 20 Ca / (μg / g) 0.2 ＜0.1 Na / (μg / g) ＜0.1 1 <![CDATA[Total chlorine (as Cl - calculated) / wt%]]> 0.17 0.37 Total acid value (mgKOH / g) 20.11 11

[0058] Table 2

[0059]

[0060] The following preparation examples illustrate the palladium-on-carbon catalyst and its preparation method provided by the present invention.

[0061] Preparation Example 1

[0062] (1) 2g of activated carbon was contacted with 1wt% HNO3 aqueous solution for acidification treatment, and then the acidified product was washed with deionized water until neutral. The washed product was then dried to obtain activated carbon carrier. The acidification conditions were: temperature 40℃, time 4h; drying temperature 100℃.

[0063] (2) 2g of the above activated carbon support was mixed with 14mL of PdCl2 solution (Pd mass concentration 25mg / mL) for impregnation. The resulting impregnated product was then allowed to stand and cool to room temperature before being contacted with KBH4 (provided as an aqueous solution of KBH4 with a concentration of 2mol / L) for reduction.

[0064] The immersion conditions were: temperature 50℃, time 2 hours;

[0065] The contact method is as follows: place the cooled impregnation product in an ice-water bath, add KBH4 aqueous solution dropwise while stirring, control the dropping rate, keep the system temperature at about 0℃, and add until no bubbles are generated;

[0066] After the reduction was completed, the reduction product was filtered, and then washed once with distilled water and once with anhydrous ethanol. The washed product was then dried under vacuum for 24 hours to obtain a Pd / C catalyst with a Pd content of 15 wt%.

[0067] Preparation Example 2

[0068] The method of preparation example 1 is the same, except that in step (2), the Pd mass concentration of the PdCl2 solution is 12.5 mg / mL, and a Pd / C catalyst with a Pd content of 7 wt% is obtained.

[0069] The following examples illustrate the method for treating chlorinated plastic oil provided by the present invention.

[0070] Example 1

[0071] (1) 100g of chlorinated plastic oil was reacted with 2.5g of sodium methoxide (the mass ratio of chlorinated plastic oil to sodium methoxide was 100:2.5) (provided as a 50wt% sodium methoxide methanol solution) and 0.5g of H2O2 (provided as a 30wt% aqueous solution) to carry out a first reaction (the mass ratio of sodium methoxide to H2O2 was 5:1). The resulting reaction product was then reacted with water and a demulsifier and mixed. The mixture was then subjected to a first oil-water separation to obtain the oil phase.

[0072] The chlorinated plastic oil is raw material oil A; the water is deionized water; the demulsifier is RP-2 demulsifier;

[0073] The conditions for the first reaction are: reaction temperature of 100℃ and reaction time of 3h;

[0074] After the first reaction, the resulting reaction product is cooled to 90°C and then mixed with water and demulsifier.

[0075] The mass ratio of water to chlorinated plastic oil is 1:1;

[0076] The amount of demulsifier used is 150 μg relative to 1g of chlorinated plastic oil;

[0077] The mixing time was 0.5 h; the first oil-water separation method was centrifugal separation, and the centrifugal separation conditions were: centrifugal speed of 1700 rpm and centrifugation time of 10 min;

[0078] (2) In the presence of a palladium-on-carbon catalyst, 12g of the above oil phase was contacted with a hydrogen donor and an alkaline solution to carry out a second reaction. The resulting reaction product was then subjected to a second oil-water separation to obtain the treated plastic oil; wherein:

[0079] The palladium-on-carbon catalyst is the Pd / C catalyst obtained in Preparation Example 1;

[0080] The mass ratio of the oil phase to the palladium-on-carbon catalyst is 120:1;

[0081] The hydrogen donor is N2H4 (which is provided in the form of 98wt% hydrazine hydrate);

[0082] The mass ratio of the oil phase to the hydrogen donor is 120:1;

[0083] The alkaline solution is an aqueous solution of NaOH (concentration of 0.24 wt%).

[0084] The mass ratio of the oil phase to the alkaline solution is 1:1.

[0085] The conditions for the second reaction are: reaction temperature 70℃, reaction time 1h, reaction pressure atmospheric pressure; H2 bubbles are continuously bubbled in during the reaction at a flow rate of 10mL / min.

[0086] The total chlorine content of the obtained oil phase and the treated plastic oil were analyzed, and the results are shown in Table 3.

[0087] Example 2

[0088] The method is the same as in Example 1, except that:

[0089] In step (1), the mass ratio of sodium methoxide to H2O2 is 2.5:1, and the ratio of chlorinated plastic oil to sodium methoxide is 100:2.5; all other parameters are the same, resulting in an oil phase.

[0090] In step (2), the reaction temperature of the second reaction is 80°C, and the mass ratio of the oil phase to the palladium-carbon catalyst is 120:1; all other conditions are the same, and the treated plastic oil is obtained.

[0091] The total chlorine content of the obtained oil phase and the treated plastic oil were analyzed, and the results are shown in Table 3.

[0092] Example 3

[0093] The method is the same as in Example 1, except that:

[0094] In step (1), the mass ratio of sodium methoxide to H2O2 is 5:1, the mass ratio of chlorinated plastic oil to sodium methoxide is 100:5, and all other parameters are the same, resulting in an oil phase.

[0095] In step (2), the reaction temperature of the second reaction is 90°C, and the mass ratio of the oil phase to the palladium-carbon catalyst is 120:1; all other conditions are the same, and the treated plastic oil is obtained.

[0096] The total chlorine content of the obtained oil phase and the treated plastic oil were analyzed, and the results are shown in Table 3.

[0097] Example 4

[0098] The method is the same as in Example 1, except that:

[0099] In step (1), the mass ratio of sodium methoxide to H2O2 is 2.5:1; the mass ratio of chlorinated plastic oil to sodium methoxide is 100:5; all other parameters are the same, resulting in an oil phase.

[0100] In step (2), the reaction temperature of the second reaction is 70°C, and the mass ratio of the oil phase to the palladium-carbon catalyst is 120:2; all other parameters are the same, resulting in the treated plastic oil.

[0101] The total chlorine content of the obtained oil phase and the treated plastic oil were analyzed, and the results are shown in Table 3.

[0102] Example 5

[0103] The method is the same as in Example 1, except that:

[0104] In step (1), the mass ratio of sodium methoxide to H2O2 is 5:1; the mass ratio of chlorinated plastic oil to sodium methoxide is 100:10; all other parameters are the same, resulting in an oil phase.

[0105] In step (2), the reaction temperature of the second reaction is 80°C, and the mass ratio of the oil phase to the palladium-carbon catalyst is 120:2; all other parameters are the same, resulting in the processed plastic oil.

[0106] The total chlorine content of the obtained oil phase and the treated plastic oil were analyzed, and the results are shown in Table 3.

[0107] Example 6

[0108] The method is the same as in Example 1, except that:

[0109] In step (1), the mass ratio of sodium methoxide to H2O2 is 2.5:1; the mass ratio of chlorinated plastic oil to sodium methoxide is 100:10; all other parameters are the same, resulting in an oil phase.

[0110] In step (2), the reaction temperature of the second reaction is 90°C, and the mass ratio of the oil phase to the palladium-carbon catalyst is 120:2; all other parameters are the same, resulting in the treated plastic oil.

[0111] The total chlorine content of the obtained oil phase and the treated plastic oil were analyzed, and the results are shown in Table 3.

[0112] Example 7

[0113] The method is the same as in Example 1, except that in step (2), the palladium on carbon catalyst is the Pd / C catalyst obtained in Preparation Example 2, and the rest are the same.

[0114] The total chlorine content of the obtained oil phase and the treated plastic oil were analyzed, and the results are shown in Table 3.

[0115] Example 8

[0116] The method of Example 1 was followed, except that the chlorine-containing plastic oil was raw material oil B, and all other aspects were the same. The total chlorine content of the obtained oil phase and the treated plastic oil were analyzed, and the results are shown in Table 3.

[0117] Comparative Example 1

[0118] The method of Example 1 was followed, except that sodium methoxide was replaced with NaOH, and all other steps were the same. The total chlorine content of the obtained oil phase and the treated plastic oil were analyzed, and the results are shown in Table 3.

[0119] Table 3

[0120]

[0121]

[0122] The results above show that the method provided by this invention has a good dechlorination effect when treating chlorinated plastic oil, and it does not require additional hydrogenation or dechlorination equipment, resulting in low cost.

[0123] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for treating chlorinated plastic oil, characterized in that, The method includes the following steps: (1) Chlorinated plastic oil is contacted with sodium methoxide and H2O2 to carry out a first reaction, and then the resulting reaction product is contacted with water and a demulsifier for mixing. The resulting mixture is then subjected to a first oil-water separation to obtain an oil phase; the mass ratio of sodium methoxide to H2O2 is 1-10:1; the reaction temperature of the first reaction is 70-120℃. (2) In the presence of a palladium-on-carbon catalyst, the oil phase is contacted with a hydrogen donor and an alkaline solution, and H2 is bubbled in to carry out a second reaction. The resulting reaction product is then subjected to a second oil-water separation. The reaction temperature of the second reaction is 70-150°C. The Pd content in the palladium on carbon catalyst is 15-20 wt%.

2. The method according to claim 1, wherein, In step (1), the sodium methoxide is provided in the form of a sodium methoxide methanol solution; in the sodium methoxide methanol solution, the mass ratio of sodium methoxide to methanol is 0.5-1.5:

1.

3. The method according to claim 2, wherein, In the sodium methoxide methanol solution, the mass ratio of sodium methoxide to methanol is 0.8-1.2:

1.

4. The method according to claim 1, wherein, In step (1), the mass ratio of sodium methoxide to H2O2 is 2.5-5:

1.

5. The method according to claim 1, wherein, In step (1), the mass ratio of the chlorinated plastic oil to the sodium methoxide is 100:0.1-15.

6. The method according to claim 5, wherein, In step (1), the mass ratio of the chlorinated plastic oil to the sodium methoxide is 100:2.5-10.

7. The method according to any one of claims 1-6, wherein, In step (1), the reaction time of the first reaction is 1-5 hours.

8. The method according to claim 7, wherein, The conditions for the first reaction include: a reaction temperature of 80-110℃ and a reaction time of 1-3h.

9. The method according to any one of claims 1-6, wherein, In step (1), the mass ratio of the water to the chlorinated plastic oil is 1-2:

1.

10. The method according to claim 9, wherein, The mass ratio of water to chlorinated plastic oil is 1-1.5:

1.

11. The method according to any one of claims 1-6, wherein, In step (1), the demulsifier is at least one of fatty alcohol polyoxypropylene polyoxyethylene ether, polyol polyoxypropylene polyoxyethylene ether, polyethylene polyamine polyoxypropylene polyoxyethylene ether, alkylphenol polyoxypropylene polyoxyethylene ether and alkylphenol amine polyoxypropylene polyoxyethylene ether.

12. The method according to any one of claims 1-6, wherein, In step (1), the amount of the demulsifier is 50-200 μg relative to 1g of the chlorinated plastic oil.

13. The method according to claim 12, wherein, The amount of the demulsifier is 100-150 μg relative to 1g of the chlorine-containing plastic oil.

14. The method according to any one of claims 1-6, wherein, In step (2), the preparation method of the palladium-carbon catalyst includes: impregnating activated carbon with an aqueous solution of palladium chloride salt, and then reducing the obtained impregnated product with KBH4.

15. The method according to claim 14, wherein, Prior to the impregnation process, the activated carbon is first subjected to an acidification treatment.

16. The method according to claim 15, wherein, The acidification treatment conditions include: a temperature of 30-50℃ and a time of 1-5h.

17. The method of claim 14, wherein, The impregnation conditions include a temperature of 40-60℃ and a time of 1-2 hours.

18. The method according to claim 14, wherein, The reduction temperature is 0℃±1℃.

19. The method according to any one of claims 1-6, wherein, In step (2), the mass ratio of the oil phase to the palladium-carbon catalyst is 120:1-2.

20. The method according to any one of claims 1-6, wherein, In step (2), the hydrogen donor is at least one of formate, phosphite, hydrazine, alcohol and metal hydride.

21. The method according to any one of claims 1-6, wherein, In step (2), the mass ratio of the oil phase to the hydrogen donor is 120:0.1-5.

22. The method according to claim 21, wherein, The mass ratio of the oil phase to the hydrogen donor is 120:0.2-2.

23. The method according to any one of claims 1-6, wherein, In step (2), the alkaline solution is an aqueous solution of NaOH, and the concentration of the alkaline solution is 0.1-2 wt%.

24. The method according to claim 23, wherein, The concentration of the alkaline solution is 0.2-1 wt%.

25. The method according to any one of claims 1-6, wherein, In step (2), the mass ratio of the oil phase to the alkaline solution is 1:0.5-1.

5.

26. The method according to any one of claims 1-6, wherein, In step (2), the conditions for the second reaction include: a reaction time of 0.5-5 h and a reaction pressure of less than 1 MPa.

27. The method according to claim 26, wherein, The conditions for the second reaction include: a reaction temperature of 70-130℃, a reaction time of 1-3h, and a reaction pressure of atmospheric pressure to 0.8MPa.

28. The method according to any one of claims 1-6, wherein, The chlorine content of the chlorine-containing plastic oil is 200-4000 μg / g.

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