Method for removing contaminants from waste plastic oil

Abstract

A process for removing contaminants from a contaminated liquid waste plastic oil, the process comprising: (i) contacting the contaminated liquid waste plastic oil having an initial contaminant content with a wash stream having a pH greater than a pH, the wash stream comprising a wash solvent, a phase transfer catalyst, and optionally a reducing agent; (ii) mixing the contaminated liquid waste plastic oil with the wash stream to produce a reaction mixture; (iii) settling the reaction mixture into at least one hydrocarbon phase having a final contaminant content less than the initial contaminant content and an aqueous phase containing the contaminant and at least one reaction product of the wash stream; and (iv) separating the hydrocarbon phase from the aqueous phase.

Description

Technical Field

[0001] The present invention relates to a method for removing contaminants from waste plastic oil streams. Background Art

[0002] Waste plastic oil is an oil produced from waste plastic material. In addition to containing desirable hydrocarbons, which typically have a high content of paraffins (>30%), waste plastic oil may also contain undesirable contaminants such as heteroatom-containing compounds, for example organic halides and siloxanes.

[0003] Waste plastic oil is useful raw material, and can be fed in steam cracker or catalytic cracker to produce useful and high-value chemicals, such as olefins, comprise ethene and propylene, and they are monomers that can be used for making new plastics.Yet, before standing cracking process, the pollutant existing in the waste plastic oil must be processed, to prevent the problem that causes by the fouling and corrosion of process equipment or the poisoning (for example, by catalyst deactivation) of downstream unit.The example of the pollutant that may need to be removed from the waste plastic oil before being fed to cracker comprises heteroatoms and heteroatomic compound, such as metal, organic acid, organohalide, phenol and substituted phenol, caprolactam and siloxane.

[0004] Hydrotreating is considered as the standard solution for removing heteroatomic organic compounds (such as organochlorides) from waste plastic oil streams. An alternative method utilizes the following: first washing, then extracting, to remove pollutants from oil. However, there are problems associated with these known methods for removing pollutants from waste plastic oil streams. Hydrotreating requires an expensive hydrogen supply. In addition, a reactor containing a catalyst and / or an adsorbent is required, and this catalyst and / or this adsorbent is prone to deactivation or saturation depending on the pollutant level, thereby causing high operating costs. These reactors operate at high temperature and high pressure, thereby also causing high investment costs. In addition, extraction methods generally relate to washing steps and the extraction step using toxic extraction solvents, usually require energy-intensive purification steps, and may produce a large amount of waste oil effluent streams rich in pollutants.

[0005] Organic chlorides (such as tetrachloromethane, trichloromethane (chloroform) and dichloromethane) are particularly problematic pollutants in chemical processing plants because their presence during chemical processing leads to the production of hydrochloric acid. Hydrochloric acid attacks metals, leading to equipment corrosion and the associated risks of leaks and other safety incidents. If contamination levels are significantly higher than desired or permitted limits, further processing of the contaminated waste plastic oil can be inefficient and challenging in terms of logistics and storage.

[0006] Silicon-containing compounds, such as siloxanes, are also particularly problematic when present as contaminants in waste plastic oils, especially when not removed prior to subjecting the waste plastic oils to the cracking process. Siloxanes can cause fouling of process equipment and poisoning of catalysts downstream in steam crackers.

[0007] Oxygenates such as organic acids, phenol / substituted phenols, and caprolactam can cause fouling or corrosion of process equipment and poisoning of catalysts downstream of the steam cracker.

[0008] It is highly desirable to provide an alternative effective method for removing chemical contaminants (particularly oxygenates, nitrogen compounds, organic halides and siloxanes) from waste plastic oils. It would be even more preferred if such a method could be carried out without increasing complex equipment and infrastructure. It is also preferred to provide a method for removing contaminants that does not involve the hydrogen required for hydrotreating. It is also preferred to provide a method that does not involve toxic extraction solvents and is simpler than a method that includes a washing step and a subsequent extraction step. It is also preferred to provide a method that is less energy intensive than hydrotreating and extraction methods. In addition, it is preferred to provide a method with a high hydrocarbon recovery rate. Summary of the Invention

[0009] According to the present invention, there is provided a method for removing pollutants from contaminated liquid plastic waste oil, the method comprising:

[0010] (i) contacting the contaminated liquid plastic waste oil having an initial contaminant content with a wash stream having a pH greater than 10, the wash stream comprising a wash solvent, a phase transfer catalyst and optionally a reducing agent;

[0011] (ii) mixing the contaminated liquid plastic waste oil with the wash stream to produce a reaction mixture;

[0012] (iii) settling the reaction mixture into at least one hydrocarbon phase and an aqueous phase, the hydrocarbon phase having a final contaminant content that is less than the initial contaminant content, the aqueous phase containing the contaminant and at least one reaction product of the wash stream, and

[0013] (iv) separating the hydrocarbon phase from the aqueous phase.

[0014] It has been discovered that the method of the present invention provides an effective and efficient way to remove undesirable contaminants (such as organic acids, phenols, substituted phenols, caprolactams, organic halides, and siloxanes) from contaminated liquid plastic waste oils without the problems associated with the known methods mentioned above. Once such contaminants are removed, the resulting purified liquid plastic waste oil can be more easily subjected to processes such as steam cracking and catalytic cracking without the negative side effects associated with the contaminants. DETAILED DESCRIPTION

[0015] Although the methods of the present invention and the streams used in the methods are described as "comprising," "containing," or "including" one or more of the various described steps and components, respectively, they may also "consist essentially of" or "consist of" the one or more various described steps and components, respectively.

[0016] In the context of the present invention, where a stream or phase comprises two or more components, these components are selected in such a total amount that does not exceed 100%.

[0017] Furthermore, when upper and lower limits are cited for a property, a range of values ​​defined by the combination of any upper limit and any lower limit is also implied.

[0018] Surprisingly, have found that, can remove pollutant (such as organic acid, organohalide, phenol, substituted phenol, caprolactam and siloxane) from polluted waste plastic oil, wherein this washing stream comprises washing solvent, phase-transfer catalyst and optional reducing agent by making contaminated waste plastic oil contact with the washing stream with the pH greater than 10.Contaminated waste plastic oil is mixed to produce reaction mixture with washing stream.Then reaction mixture is settled to hydrocarbon phase and water.Hydrocarbon phase has the ultimate density of pollutant (such as organic acid, phenol, substituted phenol, caprolactam, organohalide or siloxane), and this ultimate density is less than the initial contaminant content of contaminated waste plastic oil.Aqueous phase comprises at least a reaction product of pollutant and washing stream.Separable hydrocarbon phase and water then.

[0019] The hydrocarbon phase may then be subjected to further processing such as catalytic cracking, steam cracking, and gasification, etc. Alternatively, the hydrocarbon phase may be subjected to further processing such as solvent extraction, hydrotreating, and adsorption, etc., before being fed to a catalytic cracker, steam cracker, or gasifier.

[0020] The present invention also relates to a process for steam cracking a hydrocarbon feed, wherein the hydrocarbon feed comprises a hydrocarbon phase produced by the process of the present invention. Furthermore, the present invention relates to a process for catalytic cracking a hydrocarbon feed, wherein the hydrocarbon feed comprises a hydrocarbon phase produced by the process of the present invention.

[0021] Furthermore, the present invention relates to a method for steam cracking a hydrocarbon feed, comprising the steps of: (a) producing a hydrocarbon phase by the method of the present invention, and (b) steam cracking a hydrocarbon feed comprising at least a portion of the hydrocarbon phase produced in step (a). Still further, the present invention relates to a method for catalytically cracking a hydrocarbon feed, comprising the steps of: (a) producing a hydrocarbon phase by the method of the present invention, and (b) catalytically cracking a hydrocarbon feed comprising at least a portion of the hydrocarbon phase produced in step (a).

[0022] The aqueous phase can be disposed of in effluent treatment processes known to those skilled in the art.

[0023] Method of the present invention is applicable to removing multiple pollutants, comprise heteroatoms or compounds containing heteroatoms.As used herein, term " heteroatom " refers to any atom that is not carbon or hydrogen.The example of pollutant present in waste plastic oil stream comprises organic halide (such as organic chloride, bromide and fluoride), nitrogen, oxygen, sulphur, metal (such as aluminium, calcium, chromium, copper, iron, potassium, magnesium, sodium, nickel, phosphorus, silicon and zinc), organic acid, phenol, substituted phenol, caprolactam and siloxane and their mixture.

[0024] The method of the present invention is particularly advantageous for removing organic halides, organic acids, phenols, substituted phenols, caprolactams and siloxanes from liquid waste plastic oils.

[0025] Organic chlorides include, but are not limited to, chloroform, carbon tetrachloride, tetrachloroethylene, vinyl chloride, chlorobenzene, chloroprene, propylene dichloride, methylene chloride, and trichloroethylene. In chemical processes, organic chlorides are not tolerated at very high levels.

[0026] Examples of siloxane contaminants include cyclic siloxanes such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, tetradecamethylcycloheptasiloxane, hexadecamethylcyclooctasiloxane, octadecamethylcyclononasiloxane, cyclodecasiloxane, and icosylsiloxane, and mixtures thereof.

[0027] When the contaminant is an organic chloride, the initial organic chloride content expressed as ppmw Cl in the contaminated waste plastic oil prior to the method of the present invention may be greater than 0 ppmw or greater than 10 ppmw, or at least 20 ppmw, or at least 50 ppmw, or at least 100 ppmw, and may be at most 5000 ppmw, or at most 3000 ppmw, based on the total weight of the contaminated waste plastic oil. The final organic chloride content expressed as ppmw Cl in the hydrocarbon phase, based on the total weight of the hydrocarbon phase, is preferably no more than 200 ppmw, or no more than 100 ppmw, or no more than 25 ppmw, or no more than 10 ppmw, preferably no more than 5 ppmw. In a preferred embodiment herein, the final organic chloride expressed as ppmw Cl content is 30% less, more preferably 50% less, or even more preferably 70% less than the initial organic chloride content expressed as ppmw Cl.

[0028] When the contaminant is siloxane, the initial siloxane content, expressed as ppmw Si, in the contaminated waste plastic oil prior to the process of the present invention may be greater than 0 ppmw, or greater than 10 ppmw, or at least 20 ppmw, or at least 50 ppmw, or at least 100 ppmw, and may be up to 5000 ppmw, or up to 3000 ppmw, based on the total weight of the contaminated waste plastic oil. The final siloxane content, expressed as ppmw Si in the hydrocarbon phase, based on the total weight of the hydrocarbon phase, is preferably no more than 200 ppmw, or no more than 100 ppmw, or no more than 25 ppmw, or no more than 10 ppmw, preferably no more than 5 ppmw. In a preferred embodiment herein, the final siloxane content, expressed as ppmw Si, is 30% less, more preferably 50% less, and even more preferably 70% less than the initial siloxane content, expressed as ppmw Si.

[0029] Contaminated waste plastic oil can be any waste plastic oil that has not yet been subjected to further processing.Contaminated waste plastic oil is produced by liquefaction, pyrolysis, thermal cracking, hydrothermal treatment or catalytic cracking of waste plastic material usually. The preferred method of producing contaminated waste plastic oil is via the pyrolysis or liquefaction of waste plastic material, preferably in a waste plastic liquid plant (WPLP), carry out. In liquefaction, product remains in liquid form (under elevated pressure), and in pyrolysis, forms gas and steam, which form liquid plastic pyrolysis oil when condensed. The waste plastics used in the waste plastic liquid plant are polyolefins and polystyrene normally. PET and PVC also can be used in WPLP, but these include high levels of pollutants, such as chlorides and oxygenates usually. Contaminated waste plastic oil has a boiling range (final boiling point of approximately 450 ℃ to 650 ℃) from light naphtha to heavy diesel usually.

[0030] The wash stream comprises a wash solvent, a phase transfer catalyst and optionally a reducing agent.Importantly, the wash stream has a pH greater than 10, preferably greater than 11, more preferably greater than 12, even more preferably greater than 13, or greater than 14.

[0031] In a preferred embodiment, the washing solvent is an aqueous solution of an alkali metal salt or an alkaline earth metal salt. Examples of suitable alkali metal or alkaline earth metal salts are lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide and mixtures thereof. In a preferred embodiment, the washing solvent is a caustic solution, i.e., based on NaOH.

[0032] Phase transfer catalyst (PTC) is a catalyst that promotes the migration of reactants from one phase to another phase in which the reaction occurs. Suitable phase transfer agents include quaternary ammonium salt compounds, quaternary phosphonium salt compounds, crown ethers, cryptands, polyethylene glycols, and mixtures thereof. Preferably, the phase transfer agent is selected from quaternary ammonium salts, quaternary phosphonium salts, and mixtures thereof. Examples of suitable quaternary ammonium salts and quaternary phosphonium ammonium salts include methyltributyl-ammonium chloride, benzyltriethylammonium hydroxide, tetrabutylammonium hydroxide, tetrabutylammonium sulfate hydroxide, tetrapentylammonium hydroxide, tetrahexylammonium hydroxide, trioctylpropylammonium hydroxide, decyltripropylammonium hydroxide, decyltributylammonium hydroxide, dodecyltrimethylammonium hydroxide, tetradecyltrimethylammonium hydroxide, pentadecyltrimethylammonium hydroxide, hexadecyltrimethylammonium hydroxide, hexaalkylphosphonium bromide, ethyltriphenylphosphonium bromide, and mixtures thereof. Examples of suitable crown ethers include 15-crown-5-ether, 18-crown-6 ether, dibenzo-18-crown-6 ether, and mixtures thereof.

[0033] In a preferred embodiment herein, the phase transfer agent is methyltributyl-ammonium chloride or methyltributyl-ammonium hydroxide.

[0034] The phase transfer agent is preferably present in an amount of 0.01 wt% to 1 wt%, more preferably 0.1 wt% to 0.5 wt% based on the weight of the wash stream.

[0035] When present, suitable reducing agents include metals such as potassium, calcium, barium, sodium, and magnesium, and compounds containing hydride ions such as alkali metal hydrides (such as NaH, LiH), alkaline earth metal hydrides (such as CaH2), and salts of boron hydrides (such as sodium borohydride, lithium borohydride, or the sodium or lithium salts of aluminum hydride, gallium hydride, indium hydride, thallium hydride).

[0036] Preferably, the boron hydride is boron hydride or aluminum hydride, more preferably boron hydride. Preferably, the salt of the boron hydride is an alkali metal salt, wherein the alkali metal can be any of lithium, sodium, potassium, rubidium, and cesium, more preferably any of lithium, sodium, and potassium, and most preferably sodium. Examples of suitable salts of boron hydrides include sodium borohydride, lithium aluminum hydride, and diisobutylaluminum hydride. Most preferably, the salt is sodium borohydride (NaBH4).

[0037] When the contaminant to be removed is an organic halide, it is preferred to select a reducing agent that is capable of reacting with the organic halide contaminant to form hydrohalic acid and hydrocarbons, such as sodium borohydride.

[0038] Preferably, an excess reducing agent is used in the present invention. Preferably, the amount of reducing agent is in the range of 1 to 5 times, more preferably 1.1 to 3 times, the stoichiometric amount required to react with the pollutant compounds (e.g., organic halides) in the liquid waste plastic oil.

[0039] In a preferred embodiment herein, a wash stream is prepared using an aqueous solution of a caustic, a phase transfer agent, and optionally an alkali metal salt of a boron hydride. Additional water may also be added to the wash stream, the contaminated waste plastic oil, and / or additional water may also be added when the wash stream is in contact with and / or mixed with the contaminated waste plastic oil.

[0040] The wash stream may be contacted with the contaminated waste plastic oil in several ways, including adding the wash stream to a tank or container of the contaminated waste plastic oil.

[0041] In one embodiment of the present invention, the contaminated waste plastic oil and the wash stream are contacted at a temperature of 25 to 100° C., preferably 30 to 70° C., more preferably 40 to 60° C. This can be achieved by using a cold wash stream having a temperature in the range of 25 to 100° C., preferably 30 to 70° C., more preferably 40 to 60° C.

[0042] In another embodiment of the present invention, the contaminated waste plastic oil and the wash stream are contacted at a hot temperature of greater than 100° C. to 250° C., preferably 150° C. to 250° C., more preferably 150° C. to 200° C. This can be achieved by using a hot wash stream having a temperature in the range of greater than 100° C. to 250° C., preferably 150° C. to 250° C., more preferably 150° C. to 200° C. The hot wash stream is particularly useful for removing organic chlorides from the waste plastic oil and also further improves the removal of siloxanes.

[0043] Advantageously, the contaminated waste plastic oil can be contacted with the wash stream by injecting the wash stream during tank-to-tank transfer or by injecting the wash stream into the contaminated waste plastic oil when loading into the container. In this way, the contaminated waste plastic oil and the wash stream mix during the contacting step.

[0044] The reaction mixture can be processed in different types of process units, such as a column type with random or structured packing, trays or other contacting internals; a staged mixer / settler type with a regular arrangement or in a column; an arrangement with multiple mixer stages (in separate vessels, a single divided vessel or in a column); a static mixer followed by a settler; or a combination of process units. During the mixing step, it is important to provide sufficient power input to maintain sufficient kLa, where kLa is expressed in seconds. -1The mass transfer coefficient given. Suitable mechanical stirring devices include static mixers, stirred vessels, high shear rotary mixers or other mixing devices with rotating parts, continuous stirred tank reactors (CSTR) and plug flow reactors (PFR) etc. For mixing and sedimentation steps, a mixer / settler arrangement can be used. For the mixer / settler arrangement, it is important to achieve efficient and stable emulsions in the mixer and to achieve relatively rapid demulsification in the settler. The PFR or countercurrent (piston) flow of the washing stream and the waste plastic oil may be better than the CSTR type flow pattern to ensure that the washing stream and the waste plastic oil reach maximum removal efficiency. Alternatively, mixing can be carried out by removing a portion of the contents of the container at one point of the container or tank; circulating the portion via an external pipeline; and returning the portion to the container or tank at different points. Alternatively, mixing can be carried out by a contact tower or a fiber membrane contactor.

[0045] The residence time that the waste plastic oil is in contact with the wash stream is on the order of a few minutes to a few hours. It is important that the waste plastic oil and the wash stream are well dispersed and this will determine the time for mixing.

[0046] After mixing, the reaction mixture comprising the contaminated waste plastic oil, the wash stream, and any reaction products of the wash stream and the contaminated waste plastic oil is allowed to settle. The reaction of the contaminants with the wash stream can continue until the aqueous phase and the hydrocarbon phase settle into two substantially distinct phases. However, the reaction rate will decrease over time during the settling period.

[0047] After settling, the hydrocarbon phase is separated from the aqueous phase. This can be done in a variety of ways known to those skilled in the art, such as, but not limited to, by draining the aqueous phase from the bottom of the tank or container and / or removing the hydrocarbon phase from the top of the tank or container. Decanters, centrifuges, and the like can be used in this separation step.

[0048] The aqueous phase (eg containing the spent wash stream) may be recycled back upstream of the mixing step (ii).

[0049] Optionally, after separating the hydrocarbon phase from the aqueous phase, the hydrocarbon phase can be subjected to a further washing step with water and / or a further extraction step using an extraction solvent to remove any remaining contaminants. An example of a suitable extraction solvent for this purpose is N-methyl-2-pyrrolidone (NMP), but other solvents including glycols, triols, diketones, glycol ethers, amides, DMSO, NFM, and furfuryl may also be used. Further details on such extraction steps, including suitable extraction solvents, can be found in WO2018 / 104443, the entire contents of which are incorporated herein by reference.

[0050] The hydrocarbon phase may be flushed with water or an aqueous solution to remove traces of wash streams that may carry contaminants.

[0051] Example

[0052] Example 1 (cold caustic soda experiment)

[0053] Oscillating tube in laboratory testing: influence of PTC addition (PTC = phase transfer catalyst)

[0054] Tests were conducted in an oscillating tube at different residence times (mixing times) to evaluate the effects of temperature, residence time, and the addition of PTC and methyltributylammonium chloride (MTBAC) on the removal efficiency of Si compounds. The results for two different residence times (i.e., 2 minutes and 5 minutes) are shown in Tables 1 and 2. These tests were conducted at a 2:1 oil to solvent (water) volume ratio and atmospheric pressure. Commercial plastic pyrolysis oil samples were used for the tests. The pH of the (washing) solvent (water) was 14.

[0055] Table 1: Laboratory data in an oscillating tube used to evaluate the effects of temperature, residence time, and PTC addition on Si removal. Test (stay time is 2 minutes) :

[0056]

[0057] Table 2: Laboratory data in an oscillating tube used to evaluate the effects of temperature, residence time, and PTC addition on Si removal. Test (stay time is 5 minutes) :

[0058]

[0059]

[0060] From the results in Tables 1 and 2, it can be seen that PTC addition enhances the removal of Si from plastic oils in the low temperature range tested (ie, at 26°C and 40°C).

[0061] Example 2 (Hot Caustic Soda Experiment)

[0062] The tests were carried out at elevated temperatures using caustic in a dedicated unit consisting of four high-temperature oscillating autoclaves made of Hastelloy. The reactor temperature was set to 140°C, using a heated oil bath as the heat exchange medium. The pressure was set high enough (typically below 30 bar) to prevent evaporation of hydrocarbons, and the residence time was set to 4 hours. All tests were carried out with commercial pyrolyzed plastic raw material samples. After exposure to caustic at elevated temperatures, the oil fraction was separated and washed three times with water (2 volumes of water and 1 volume of oil) at room temperature. The pH of the (washing) solvent (water) was 14.

[0063] The results are summarized in Table 3 below.

[0064] Table 3: Effect of PTC and / or reducing agent addition on the removal of Cl and Si compounds contained in plastic oil at 140°C ring

[0065] Test 1 Test 2 Test 3 Test 4 Oil volume (ml) 50 50 50 50 Solvent volume [water] (ml) 50 50 4 3.2 NaOH% in solvent (weight) 10 10 50 18.75 Reaction temperature (℃) 140 140 140 140 Reaction pressure (bar-absolute) 14 14 14 14 Stay time (hours) 4 4 4 4 PTC: Name, Quantity (g) none MTBAC 0.5g none MTBAC 1.0g Reducing agent: name and amount in g none none NaBH4, 0.3g NaBH4, 0.5g Cl in crude oil feed (ppmw) 102 102 102 102 Cl in treated oil (ppmw) 23 26 37 22 Si in crude oil feed (ppmw) 25 25 25 25 Si in treated oil (ppmw) 9 1 2 0

[0066] Test 1 can be considered a baseline because no PTC was added (Phase Transfer Catalyst) No reducing agent was added. The results show that at high temperatures (such as 140°C) and under the tested reaction conditions, the effect of adding a reducing agent (Test 3) or PTC (Test 2) is substantially reflected in Si removal, as shown in Tests 2 and 3. Furthermore, in Test 4, where both a reducing agent and PTC were added, all silicon-containing compounds were removed from the pyrolysis oil. Furthermore, when compared to Test 1, the additives (reducing agent and PTC) had little or no effect on Cl- compound removal (all Tests 2, 3, and 4).

[0067] In summary, the results show that high reactor temperature combined with the addition of PTC and / or reducing agent can significantly improve the removal of silicon-containing compounds contained in pyrolysis oil.

[0068] The addition of PTC has been observed to increase oil recovery by several percentage points. In our tests, oil recovery was found to increase from 90% to 93%. PTC addition also improves settling behavior, which may increase separation efficiency in the settler.

Claims

1. A method for removing pollutants from contaminated liquid waste plastic oil, the method comprising: (i) contacting the contaminated liquid waste plastic oil having an initial contaminant content with a wash stream having a pH greater than 10, the wash stream comprising a wash solvent, a phase transfer catalyst and optionally a reducing agent; (ii) mixing the contaminated liquid waste plastic oil with the wash stream to produce a reaction mixture; (iii) settling the reaction mixture into at least one hydrocarbon phase and an aqueous phase, the hydrocarbon phase having a final contaminant content that is less than the initial contaminant content, the aqueous phase containing the contaminant and at least one reaction product of the wash stream, and (iv) separating the hydrocarbon phase from the aqueous phase.

2. The process according to claim 1, wherein the temperature of the wash stream is from 25°C to 100°C.

3. The method of claim 1, wherein the temperature of the wash stream is greater than 100°C to 250°C.

4. The process according to any one of claims 1 to 3, wherein the wash stream has a pH above 13.

5. The method according to any one of claims 1 to 4, wherein the contaminant is a heteroatom or a compound containing a heteroatom.

6. The method according to any one of claims 1 to 5, wherein the contaminant is selected from the group consisting of organic acids, organic halides, phenols, substituted phenols, caprolactams, siloxanes and mixtures thereof.

7. The method according to any one of claims 1 to 6, wherein the washing solvent is an aqueous solution of an alkali metal salt or an alkaline earth metal salt.

8. The process according to any one of claims 1 to 7, wherein the washing solvent is an aqueous caustic solution.

9. The method according to any one of claims 1 to 8, wherein the phase transfer catalyst is selected from the group consisting of quaternary ammonium salt compounds, quaternary phosphonium salt compounds, crown ethers, cryptands, polyethylene glycols, and mixtures thereof.

10. The process according to any one of claims 1 to 9, wherein the phase transfer catalyst is a quaternary ammonium salt.

11. The method according to any one of claims 1 to 10, wherein the reducing agent is selected from the group consisting of alkali metals, alkaline earth metals, salts of alkali metal hydrides, alkaline earth metal hydrides and boron hydrides, and mixtures thereof.

12. The method according to any one of claims 1 to 11, wherein the liquid waste plastic oil is produced by liquefaction, pyrolysis, thermal cracking, hydrothermal treatment or catalytic cracking of waste plastic materials.

13. A method for steam cracking a hydrocarbon feed, the method comprising the steps of: (a) producing a hydrocarbon phase by a process according to any one of claims 1 to 12, and (b) steam cracking a hydrocarbon feed comprising at least a portion of the hydrocarbon phase produced in step (a).

14. A method for catalytic cracking a hydrocarbon feed, the method comprising the steps of: (a) producing a hydrocarbon phase by a process according to any one of claims 1 to 12, and (b) catalytically cracking a hydrocarbon feed comprising at least a portion of the hydrocarbon phase produced in step (a).

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