A process for pretreating liquefied waste plastic

Abstract

Herein is described method for purifying liquefied waste plastic, LWP, the method comprising the steps of i) providing a liquefied waste plastic feed (a); ii) pretreating the liquefied waste plastic feed (a) to obtain a pretreated feed (b), wherein the pretreating comprises mixing the liquefied waste plastic feed (a) with an aqueous solution to obtain an admixture, and heat-treating said admixture to obtain the pretreated feed (b); iii) phase separating the pretreated feed (b) to obtain a pretreated oil (c); iv) contacting an adsorbent with the pretreated oil (c) by dispersing the adsorbent with the pretreated oil (c) to obtain an oil-adsorbent admixture (d); and v) subjecting the oil-adsorbent admixture (d) to a solid-liquid separation to obtain purified oil (e). Herein is further described use of the purified oil in at least one catalytic hydrotreating step to obtain LWP hydrocarbons. Herein is yet further described use of high temperature pretreatment and adsorption sequentially for purifying liquefied waste plastic.

Description

[0001] A PROCESS FOR PRETREATING LIQUEFIED WASTE PLASTIC

[0002] TECHNICAL FIELD

[0003] The present disclosure generally relates to pretreating liquefied waste plastic (LWP). The disclosure relates particularly, though not exclusively, to removal of impurities from liquefied waste plastic using adsorption.

[0004] BACKGROUND

[0005] This section illustrates useful background information without admission of any technique described herein representative of the state of the art.

[0006] There is an ongoing need to reduce greenhouse gas emissions and / or carbon footprint and / or the amount of waste. Plastic waste is a global issue due to its non-biodegradability, accumulation and leakage into nature and oceans. There is a significant need to recycle and reuse plastic waste.

[0007] Oils bearing a certain degree of similarity to crude oils can be produced from plastic waste by thermally decomposing them in a thermochemical liquefaction process. These oils, which will be referred to as liquefied waste plastic (LWP) in this document, can be used as a raw material in the refineries.

[0008] However, plastic waste, especially post-consumer collected plastic waste, comprises a large variety of (also non-plastic derived) impurities that interfere with the processes in the refineries. In order to successfully recycle and reuse plastic waste, these impurities need to be removed before further processing of the recycled raw material in the refineries.

[0009] LWPs are purified by exposing them to high temperature and alkaline conditions, followed by a phase separation. In many cases, the phase separation is not satisfactory, and the resultant oils still contain high amounts of water and metallic impurities. Further processing of such impure oils poses a significant threat to refinery assets and operations as they cause e.g., corrosion, fouling, and catalyst deactivation. SUMMARY

[0010] It is an aim to solve or alleviate at least some of the problems related to prior art. The aim is to provide an ingenious method for removing impurities and residual water from liquefied waste plastic oils. The present inventors have found the use of adsorption to improve removal of impurities.

[0011] The appended claims define the scope of protection. Any examples and technical descriptions of apparatuses, systems, products and / or processes in the description and / or drawings not covered by the claims are presented as examples useful for understanding the invention.

[0012] The present inventors have found that after the typically used LWP pretreatment purification process of high temperature and alkaline conditions, the pretreated LWPs still contain relatively high amounts of impurities, such as nitrogen N, sodium Na, and residual water H2O. The present inventors have found that said impurities and residual water can be removed from the LWP feeds via adsorption.

[0013] According to a first example aspect there is provided a method for purifying liquefied waste plastic, LWP, the method comprising the steps of i) providing a liquefied waste plastic feed (a); ii) pretreating the liquefied waste plastic feed (a) to obtain a pretreated feed (b), wherein the pretreating comprises mixing the liquefied waste plastic feed (a) with an aqueous solution to obtain an admixture, and heat-treating said admixture to obtain the pretreated feed (b); iii) phase separating the pretreated feed (b) to obtain a pretreated oil (c); iv) contacting an adsorbent with the pretreated oil (c) by dispersing the adsorbent with the pretreated oil (c) to obtain an oil-adsorbent admixture (d); and v) subjecting the oil-adsorbent admixture (d) to a solid-liquid separation to obtain purified oil (e).

[0014] According to a second example aspect, there is provided a use of the purified oil obtained from the method according to the first aspect in at least one catalytic hydrotreating step to obtain recycled hydrocarbons.

[0015] According to a third example aspect, there is provided a use of high temperature pretreatment and adsorption sequentially for purifying liquefied waste plastic.

[0016] Different non-binding example aspects and embodiments have been illustrated in the foregoing paragraphs. The embodiments in the foregoing are used merely to explain selected aspects or steps that may be utilized in different implementations. Some embodiments may be presented only with reference to certain example aspects. It should be appreciated that corresponding embodiments may apply to other example aspects as well.

[0017] BRIEF DESCRIPTION OF THE FIGURES

[0018] Some example embodiments will be described with reference to the accompanying figures, in which:

[0019] Fig. 1 shows a flow chart of a method according to an example embodiment;

[0020] Fig. 2 schematically shows a LWP treatment block chart according to an example embodiment;

[0021] Fig. 3a schematically shows the first step of an adsorption according to an example embodiment; and

[0022] Fig. 3b schematically shows the second step of the adsorption according to an example embodiment.

[0023] DETAILED DESCRIPTION

[0024] In the following description, like reference signs denote like elements or steps.

[0025] All standards referred to herein are the latest revisions available at the filing date, unless otherwise mentioned.

[0026] All embodiments (such as all preferred values and / or ranges within the embodiments) of the present invention may be combined with each other to give new (preferred) embodiments, unless explicitly specified otherwise or unless such a combination would result in a contradiction.

[0027] As used herein, liquefied waste plastic (LWP) means a product effluent from liquefaction process comprising at least thermally depolymerizing waste plastic. LWP is thus a material which is obtainable by depolymerizing waste plastic (and / or other polymers). LWP may also be referred to as polymer waste-based oils, or LWP oils.

[0028] The waste plastic which forms the basis for the LWP may be separately collected and sorted waste plastic. On the other hand, it may be more favorable to utilize waste plastic from commingled collection, such as waste plastic sorted out from municipal waste and still containing other (non-plastic) components, preferably containing less than 15 wt.-% nonplastic components, or less than 10 wt.-% non-plastic components of the total waste weight. The LWP is preferably formed from polyolefin-rich waste plastic, such as waste plastic having a polyolefins content of 50 wt.-% to 100 wt.-%, preferably at least 60 wt.-%, at least 70 wt.-%, at least 80 wt.-%, or at least 90 wt.-% of the total plastic weight. The content of polyolefins may be determined using any commonly known method, such as DSC, melting enthalpy, FT-IR, or NMR, in particular solid-state NMR, which are usual in laboratories.

[0029] An LWP feed is a feed which is based on LWP, i.e. , it contains at least LWP, preferably at least 50 wt.-% LWP, such as at least 60 wt.-% LWP, at least 70 wt.-% LWP, at least 80 wt.- % LWP, or at least 90 wt.-% LWP of the total feed weight. The LWP feed may consist of LWP. The larger the content of LWP in the LWP feed, the larger the amount of waste plastic to be re-used.

[0030] The waste plastic may be derived from any source, such as (recycled or collected) postconsumer or post-industrial plastic, or sorting residue from mechanical recycling processes. In particular, the term waste plastic refers to an organic polymer material which is no longer fit for its original use or which has been disposed of for any reason. Waste plastic may more specifically refer to end-life-tires, collected post-consumer plastic (post-consumer plastic referring to any used organic polymer material in consumer goods, even if not having “plastic” properties as such), collected industrial polymer waste. The waste plastic may be solid waste plastic.

[0031] The liquefaction process is typically carried out at elevated temperatures, and under non- oxidative conditions. The liquefaction process may be carried out at elevated pressure. The liquefaction process may be carried out in the presence of a catalyst. The effluent from the liquefaction process may be employed as the liquefied waste plastic feed as such or may be subjected to fractionation (or separation) to provide a fraction (or separated liquid) of the effluent as the liquefied waste plastic feed. For example, the LWP feed may be a hydrothermal liquefaction oil or a fraction thereof. Similarly, multiple fractionations may be conducted in sequence. In addition, two or more liquefaction process effluents and / or fractions thereof may be combined to give the LWP feed. These effluents and / or fraction may have the same or similar boiling range or may have different boiling ranges. In this context, fractionation refers to fractional distillation and / or fractional evaporation.

[0032] In addition to liquid (NTP) hydrocarbons, i.e. hydrocarbons being liquid at normal temperature and pressure (NTP; 20°C, 101.325 kPa absolute), typical product effluents from liquefaction processes comprise gaseous (NTP) hydrocarbons, and hydrocarbons that are waxy or solid at NTP but become liquids upon heating, for example upon heating to 80°C. In the context of the present disclosure, liquefying or depolymerizing waste plastic means decomposing or degrading the polymer backbones of the waste plastic, typically at least thermally, to the extent yielding polymer and / or oligomer species of smaller molecular weight compared to the start, but still comprising at least liquid (NTP) hydrocarbons. In other words, as used herein, the liquefied waste plastic does not cover plastic in liquid form obtained merely by melting or by dissolving into a solvent, as these do not involve sufficient cleavage of the polymer backbones, nor waste plastic depolymerized completely to the monomer-level and thus being of gaseous (NTP) form. Liquefying or depolymerizing waste plastic may also involve cleavage of covalently bound heteroatoms such as O, S, and N from optionally present heteroatom-containing compounds.

[0033] Initially the waste plastic, or each waste plastic species in mixed waste plastic, to be subjected to liquefaction, is usually in solid state, typically having a melting point of about 100°C or more as measured by DSC as described by Larsen et al. (“Determining the PE fraction in recycled PP”, Polymer testing, vol. 96, April 2021 , 107058). However, the waste plastic, or each waste plastic species, may be melted before and / or during the liquefaction or depolymerization.

[0034] Waste plastic may contain various further components such as additives, reinforcing materials, etc., including fillers, pigments, printing inks, flame retardants, stabilizers, antioxidants, plasticizers, lubricants, labels, metals, paper, cardboard, cellulosic fibres, fiberglass, even sand or other dirt. Some of the further components may be removed, if so desired, from the waste plastic, from melted waste plastic, and / or from liquefied waste plastic using commonly known methods.

[0035] Preferably, the waste plastic to be subjected to the liquefaction process (depolymerization), and thus being the base material of the LWP feed, has an oxygen content of 15 wt.-% or less, preferably 10 wt.-% or less, more preferably 5 wt.-% or less, of the total weight of the waste plastic. The oxygen content may be 0 wt.-% and may preferably be in the range of 0 wt.-% to 15 wt.-% or 0 wt.-% to 10 wt.% of the total weight of the waste plastic. Oxygen content in wt.-% can be determined by difference using the formula 100 wt.-% - (CHN content + ash content), wherein CHN content refers to combined content of carbon, hydrogen, and nitrogen, as determined in accordance with ASTM D5291 , and ash content refers to ash content as determined in accordance with ASTM D482 / EN15403. In the present disclosure, when reference is made to a standard, the revision of January 31 , 2022 shall be meant, unless stated to the contrary. The LWP preferably comprises hydrocarbons, typically more than 5 wt.-% based on the total weight of the LWP. Typically, the LWP comprises two or more hydrocarbon species selected from paraffins, olefins, naphthenes and aromatics. The composition of the LWP may vary depending e.g. on the composition of the waste plastic, liquefaction process type and conditions, and any additional treatments. Further, the assortment of various species of waste plastic and impurities associated with collected waste may result in a presence of impurities including silicon, sulphur, nitrogen, halogens and oxygen related substances in various quantities in the LWP.

[0036] The liquefied waste plastic feed of the present invention is derived from (crude) LWP and may, for example, be crude LWP (i.e. the liquid fraction directly emerging from the liquefaction process), pre-purified LWP, or a fraction of one of the afore-mentioned.

[0037] Preferably, the liquefied waste plastic feed specifically refers to an oil or an oil-like product obtainable from liquefaction using non-oxidative thermal or thermocatalytic depolymerization of waste plastic (followed by optional subsequent fractionation and / or purification). In other words, the liquefied waste plastic feed may also be referred to as “depolymerized polymer waste” or “liquefied polymer waste”.

[0038] The method of liquefaction is not particularly limited as long as it is a depolymerization process. Typical examples are thermal depolymerization processes, such as pyrolysis (e.g. fast pyrolysis, slow pyrolysis) of waste plastic, or hydrothermal liquefaction of waste plastic.

[0039] The term “hydrothermal liquefaction” (HTL) refers to a thermal depolymerization process to convert a carbon-containing feedstock into crude-like oil under moderate temperature and high pressure using subcritical or supercritical water. The term “pyrolysis” refers to thermal decomposition of materials at elevated temperatures in a non-oxidative atmosphere.

[0040] According to a first aspect, herein is provided a method for purifying liquefied waste plastic, LWP, the method comprising the steps of i) providing a liquefied waste plastic feed (a); ii) pretreating the liquefied waste plastic feed (a) to obtain a pretreated feed (b), wherein the pretreating comprises mixing the liquefied waste plastic feed (a) with an aqueous solution to obtain an admixture, and heat-treating said admixture to obtain the pretreated feed (b); iii) phase separating the pretreated feed (b) to obtain a pretreated oil (c); iv) contacting an adsorbent with the pretreated oil (c) by dispersing the adsorbent with the pretreated oil (c) to obtain an oil-adsorbent admixture (d); and v) subjecting the oil-adsorbent admixture (d) to a solid-liquid separation to obtain purified oil (e).

[0041] The present method according to the first aspect provides higher quality purified oils, due to improved and efficient impurity removal, as well as improved residual water removal. The impurity and residual water removal is performed via adsorption using an adsorbent after a pretreatment. The present method produces high quality purified LWP oils, here referred to as purified oil(s). The purification of these oils reduces catalyst deactivation in the following process steps in the refinery. Furthermore, the harmful precipitation of the impurities in the purified oil is minimal. Also, better pumpability and filterability are enabled in the following process steps in the refinery. This reduces the need for process interruptions dedicated to cleaning fouled equipment.

[0042] Fig. 1 shows a flow chart of the method according to the first aspect. According to step i), a liquefied waste plastic feed (LWP feed) (a) is provided. According to step ii), the liquefied waste plastic feed is processed in a pretreatment step to obtain a pretreated feed (b). Said pretreatment comprises mixing the liquefied waste plastic feed (a) with an aqueous solution to obtain an admixture, and heat-treating said admixture to obtain the pretreated feed (b). The pretreatment enables removing inorganic and organic derivatives of impurities from the LWP feed by converting the impurities into water-soluble forms which enables them to be extracted into the aqueous phase. The hydrocarbons contained in the pretreated feed (b) are essentially unchanged in regard to its hydrocarbon distribution thus there is no cracking taking place. However, the impurities profile of the pretreated feed (b) is said to be improved compared to the LWP feed before step (ii).

[0043] According to step iii), the pretreated feed (b) is subjected to phase separating to obtain a pretreated oil (c). According to step iv), the adsorbent is contacted with the pretreated oil (c) by dispersing the adsorbent with the pretreated oil (c) to obtain an oil-adsorbent admixture (d). According to step v) of Fig. 1 , the oil-adsorbent admixture (d) is subjected to a solid-liquid separation to obtain purified oil (e).

[0044] According to an embodiment, said aqueous solution is alkaline. Preferably, the aqueous solution comprises alkali metal hydroxide and / or alkaline earth metal hydroxide. The alkaline pretreatment provides the necessary alkaline conditions so that organic acids can be neutralized, and impurities such as silicon, nitrogen, phosphorus, halogens, and metals can be removed from the LWP feed. Preferably, the aqueous solution comprises sodium hydroxide NaOH. The alkaline pretreatment comprising NaOH enables efficient removal of organic acids from the LWP feed.

[0045] The pretreatment step comprises preferably an alkaline substance, more preferably an alkaline substance selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides in the aqueous solution. These hydroxides are strong bases and thus allow simple adjustment of the quantity and good control of target pH level. Specifically, the substance is preferably selected from the group consisting of KOH, NaOH, LiOH, Ca(OH)2, Mg(OH)2, RbOH, Sr(OH)2 and Ba(OH)2 or any combination(s) thereof. The substance may in particular be NaOH, since this is a strong base which is readily available. However, when excess alkaline substance is used, there is a need to address the situation where the alkaline substance used in pretreatment step remains present in the pretreated oil as this can be detrimental to the catalysts used in downstream processing of the pretreated oil.

[0046] The aqueous solution preferably comprises at least 50 wt.-% water, preferably at least 70 wt.-% water, more preferably at least 85 wt.-% water or at least 90 wt.-% water of the total weight of the aqueous solution. Containing mainly water makes the pretreatment process easier to implement.

[0047] The aqueous solution preferably comprises at least 0.3 wt.-% of the alkali, more preferably at least 0.5 wt.-%, at least 1.0 wt.-%, or at least 1.5 wt.-% of the alkali, such as a metal hydroxide or of an alkali metal hydroxide as the alkali, of the total weight of the aqueous solution. Although not particularly limited, the content of the alkali, a metal hydroxide or of an alkali metal hydroxide as the alkali, is preferably 10.0 wt.-% or less, such as 6.0 wt.-% or less or 4.0 wt.-% or less of the total weight of the aqueous solution. As used herein, the percentages refer to alkali quantity calculated as 100% alkali. The present inventors have experimentally found that a high content of alkali, such as a metal hydroxide or of an alkali metal hydroxide, in the aqueous solution is beneficial from the product quality perspective.

[0048] In the pretreatment step, the pH level of aqueous alkaline solution in the admixture of LWP and aqueous alkaline solution is preferably 10.0 or more. With this pH level, high impurities removal efficiency can be ensured, in particular, silicon removal from the oil phase. Although the pretreatment efficiency is high as long as the pH level (and more preferably the actual pH of the aqueous phase) is 10.0 or more, it is favorable to use stoichiometrically excessive amount of alkali, taking into account the neutralization effect from the acidic nature of the LWP, in order to ensure that the pH after heat treatment remains sufficiently high. In view thereof, the pH level of aqueous alkaline solution in the admixture of LWP and aqueous alkaline solution is preferably in the range of 10.0 to 14.0, such as 10.2 to 13.9, 10.3 to 13.8, 10.4 to 13.6, 10.5 to 13.5, 10.6 to 13.4, 10.7 to 13.3, 10.8 to 13.2, 10.9 to 13.1 , or 11.0 to 13.0. Without limiting to any particular means of measuring the pH of the admixture, in order to determine the effectiveness of the impurity removal during the process, the pH value of the aqueous solution after the heat treatment typically needs to be sufficiently high, i.e. pH of 10 or above since the pH may fluctuate during the heat treatment.

[0049] The pretreatment is preferably carried out at a temperature of 150 °C or more, preferably 190 °C or more, such as 200 °C or more, 220 °C or more, 240 °C or more or 260 °C or more. The pretreatment is preferably carried out at a temperature of 450 °C or less, preferably 400 °C or less, 350 °C or less, or 300 °C or less. For example, the pretreatment is carried out at a temperature in the range of 200 °C to 350°C, preferably 220 °C to 330 °C, 240 °C to 320 °C, or 260 °C to 300 °C. Higher temperature accelerates the pretreatment process, improves mixing of phases, and improves solubility of impurities to the aqueous phase.

[0050] As shown in Fig. 1 step iii), the pretreated feed is subjected to phase separating the pretreated feed to obtain a pretreated oil. Preferably, the phase separating comprises separating an aqueous phase from the pretreated feed to obtain the pretreated oil.

[0051] The step of phase separation enables separating the pretreated feed to an oil phase and to an aqueous phase. The aqueous phase comprises at least part of the impurities to be removed from the pretreated feed. These impurities are removed as an effect of the pretreatment. By phase separating the pretreated feed, at least part of the impurities is conveniently removed with the aqueous phase, to obtain the pretreated oil. In certain embodiments, the pretreated oil comprises less impurities (such as Cl, Si, P, N, and carboxylic acids) than the pretreated feed. In certain embodiments, the pretreated oil comprises hydrocarbons originated from the LWP. However, the present inventors have found that the pretreated oil obtained from the phase separation may still comprise certain impurities and / or residual water and / or residual alkali.

[0052] As shown in Fig. 1 step iv), the adsorbent is contacted with the pretreated oil by dispersing the adsorbent with the pretreated oil to obtain an oil-adsorbent admixture. This enables initiating the process of efficiently removing residual impurities and water from the pretreated oil. When the adsorption occurs after the pretreatment of the liquefied waste plastic feed and the phase separation to obtain a pretreated oil, the adsorbent needs to remove a relatively limited amount of Na from the pretreated oil. If the adsorbent were added directly into the pretreatment process, the overall amount of Na would be significantly higher compared to the situation of the present solution and the adsorbent could not remove Na efficiently.

[0053] As used herein, the term “adsorption” encompasses also “absorption”. Generally, in absorption molecules are dissolved by a liquid or a solid substance (absorbent), meaning that the molecules ‘soak’ into the bulk of another phase. Generally, in adsorption atoms, ions, or molecules adhere to a surface of another phase (adsorbent). In order to avoid confusion and repetition, in the context of the present disclosure the term adsorption is used, and it is intended to encompass both processes of adsorption and absorption. Similarly, as used herein, the verb “to adsorb” encompasses also “to absorb”.

[0054] As used herein, adsorption may occur due to physisorption (van der Waals forces), chemisorption (covalent bonding), or electrostatic attraction.

[0055] In certain preferable embodiments, the adsorbent comprises a porous adsorbent. The porosity of the adsorbent enables impurities and residual water to attach to the pores of the adsorbent. Preferably, the adsorbent comprises a dry adsorbent. The dryness of the adsorbent enhances the residual water removal capability of the adsorbent.

[0056] In certain embodiments, the adsorbent is in particulate form. In certain embodiments, the adsorbent has average particle size d50 of the particulate about 25000 pm or less, preferably about 6500 pm or less, more preferably about 2000 pm or less, most preferably about 500 pm or less, such as about 50 pm or less. As used herein, the average particle size is measured by optical methods or by an air sieve.

[0057] In certain embodiments, the adsorbent comprises an elemental metal, oxide, alkoxide or solid sorption agent. Preferably, the adsorbent comprises silica. In certain embodiments, the adsorbent comprises a metal oxide, or a combination of metal oxides. This enhances the impurity and residual water removal.

[0058] In certain embodiments, the adsorbent comprises a solid sorption agent selected from the list comprising activated carbon, alumina, silica, clay materials, zeolites, ion exchange resins, absorbent organic polymers or a combination thereof. In certain preferred embodiments, the adsorbent comprises a solid sorption agent selected from the list comprising silica gel, clay, crushed clay, apatite, hydroxyapatite and combinations thereof, an alumina, such as an alumina obtained by precipitation of boehmite, a calcined alumina such as Ceralox ®, boehmite, bayerite, hydrotalcite, a spinel such as Pural ® or Puralox ®, a promoted alumina, for example Selexsorb ®, an acid promoted alumina, an alumina promoted by a zeolite and / or by a metal such as N I , Co, Mo or a combination of at least two of them, a clay treated with an acid such as Tonsil ®, a molecular sieve in the form of an aluminosilicate containing an alkaline or alkaline-earth cation, such as the 3A, 4A, 5A, 13X sieves, or a molecular sieve such as Siliporite ®, a zeolite, an activated carbon, or the combination thereof.

[0059] In certain embodiments, the adsorbent comprises an elemental metal of group 1 , 2, 6, 7, 8, 9, 10, 11 , 12, 13 of the lUPAC periodic table of elements or a mixture thereof or an alloy thereof, and / or an oxide of metals of group 1 , 2, 6, 7, 8, 9, 10, 11 , 12, 13 of the IIIPAC periodic table of elements or a mixture thereof, and / or an alkoxide of metals of group 1 , 2 of the IIIPAC periodic table of elements, or a mixture thereof.

[0060] In certain embodiments, the adsorbent comprises a combination of at least two adsorbents.

[0061] According to certain embodiments, the step iv) is carried out at a temperature between 25 °C and 150 °C. In said temperature range efficient adsorption is enabled to occur, whilst simultaneously any unfavorable chemical reactions are prevented from occurring in between the adsorbent and the pretreated oil. In an event of elevating the temperature excessively during the adsorption, there may occur harmful chemical reactions in between the adsorbent and the pretreated oil.

[0062] According to certain preferable embodiments, the step iv) has a residence time of 2 minutes to 72 hours. In certain embodiments, the step iv) further comprises subjecting the oiladsorbent admixture to agitation in a mixing vessel. This enables efficient contact between the pretreated oil and the adsorbent, which results in efficient impurity and residual water removal.

[0063] According to certain embodiments, the step iv) comprises reducing the amount of (the adsorbent adsorbs) at least one impurity selected from F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg, Hg, and / or derivatives, ions or salts thereof, and / or the H2O content of the pretreated oil by contacting the adsorbent with the pretreated oil. According to certain preferred embodiments, the step iv) comprises reducing the amount of (the adsorbent adsorbs) at least one impurity selected from N, Na, and / or derivatives, ions or salts thereof, and / or the H2O content of the pretreated oil by contacting the adsorbent with the pretreated oil. The purified oil comprises a reduced amount of impurities and residual water in comparison to the pretreated oil.

[0064] According to certain embodiments, the adsorbent adsorbs at least 20 wt.-% of the total weight of the impurities, preferably at least 50 wt.-% of the total weight of the impurities of at least one impurity selected from F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg, Hg, and / or derivatives, ions or salts thereof, and / or the H2O, preferably of at least one impurity selected from N, Na, and / or derivatives, ions or salts thereof and / or the H2O.

[0065] As shown in Fig. 1 step v), the oil-adsorbent admixture is subjected to a solid-liquid separation to obtain purified oil. In certain embodiments, in step v) the purified oil is recovered. In certain embodiments, the instant method comprises separating the adsorbent from the oil-adsorbent admixture to obtain the purified oil. In certain embodiments, the separating comprises filtration, centrifugation, settling or a combination thereof.

[0066] According to certain embodiments, the step v) comprises subjecting the oil-adsorbent admixture to a solid-liquid separation to separate the adsorbent from the oil-adsorbent admixture to obtain the purified oil having a reduced amount of at least one impurity selected from F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg, Hg, and / or derivatives, ions or salts thereof, and / or the H2O content in relation to the pretreated oil. According to certain preferred embodiments, the step v) comprises subjecting the oil-adsorbent admixture to a solid-liquid separation to separate the adsorbent from the oil-adsorbent admixture to obtain the purified oil having a reduced amount of at least one impurity selected from N, Na, and / or derivatives, ions, or salts thereof, and / or the H2O content in relation to the pretreated oil. The used adsorbent preferably comprises the impurities and residual water removed from the pretreated oil.

[0067] In certain embodiments, the method comprises removing positively and negatively charged ions from the pretreated oil. In certain embodiments, the method comprises removing positively charged ions from the pretreated oil.

[0068] In certain embodiments, the pretreated oil comprises N, Na, and / or derivatives, ions or salts thereof, and H2O. In certain preferred embodiments, the method comprises reducing the amount of N, Na, and / or derivatives, ions or salts thereof, and reducing H2O content in the pretreated oil to obtain the purified oil. In certain preferred embodiments, the method comprises reducing the amount of Na, and / or derivatives, ions or salts thereof, and reducing H2O content in the pretreated oil to obtain the purified oil.

[0069] In certain preferred embodiments, the purified oil has a reduced amount, in relation to the pretreated oil, of N, Na, and / or derivatives, ions or salts thereof, and reduced H2O content. In certain preferred embodiments, the purified oil has a reduced amount, in relation to the pretreated oil, of Na, and / or derivatives, ions or salts thereof, and reduced H2O content. This enables the use of the purified oil as further raw material in the following processes in the refinery, such as in catalytic hydrotreating step(s). The use of adsorbents as a means of removing impurities mitigates the side effect of the pretreatment step. In certain embodiments, the pretreatment step comprising alkaline aqueous conditions, increases the amount of alkali metal ions, such as Na+, in the pretreated feed. By combining the pretreatment step and adsorption step, the impurities are being effectively removed, reducing the demand on downstream processing such, as hydrotreating, which involves the use of catalysts.

[0070] In certain embodiments, the purified oil is essentially free from at least one impurity selected from N, Na, and / or derivatives, ions or salts thereof, and / or residual H2O.

[0071] According to certain embodiments, the purified oil has a moisture content of 0.05 wt.-% or less of the total weight of the purified oil.

[0072] According to certain embodiments, the purified oil has a Na content of less than 5 mg / kg, preferably less than 2 mg / kg, more preferably less than 1 mg / kg.

[0073] In certain embodiments, the purified oil recovered from the instant method is an intermediate product to be used further. In certain embodiments, the purified oil is used as a raw material. In certain embodiments, the purified oil is used as a raw material feed in a refinery. In certain embodiments, the purified oil is used in at least one catalytic hydrotreating step to obtain recycled hydrocarbons. The purified oil recovered from the instant method provided experimentally high-quality LWP oil with minimal amount of impurities and residual water.

[0074] In certain further embodiments, the method comprises using the purified oil in at least one catalytic hydrotreating step to obtain recycled hydrocarbons. According to an embodiment of the present method, the hydrotreating refers to hydrodeoxygenation, hydrodesulfurisation, hydrodenitrogenation, hydrodehalogenation (such as hydrodechlorination), hydrogenation of double bonds, hydrocracking, hydroisomerisation, any combination thereof, and it also removes some metals. According to an embodiment of the present method, the catalytic hydrotreating comprises one or more of hydrodeoxygenation, hydroisomerisation, hydrocracking, hydrodenitrogenation, hydrodesulfurisation, hydrodehalogenation or hydrogenation of double bonds. According to an embodiment of the present method, the catalytic hydrotreating comprises one or more of the preceding simultaneously or in sequence. According to an embodiment of the present method, the catalytic hydrotreating occurs in the presence of a supported catalyst. Preferably, the supported catalyst comprises at least one component selected from IIIPAC group 6, 8 or 10 of the Periodic Table of Elements. More preferably, the supported catalyst comprises Mo and at least one further transition metal on a support, such as a supported NiMo catalyst or a supported CoMo catalyst, wherein the support preferably comprises alumina and / or silica. Even more preferably, the supported catalyst comprises a supported CoMo catalyst, wherein the support comprises alumina (CoMo / AhOa) and / or the supported catalyst comprises NiMo catalyst, wherein the support comprises alumina (NiMo / AI2O3).

[0075] Said catalysts can lose their activity if impurity compounds form and precipitate thereon. Therefore, removal of impurity compounds, such as metals, Si, and N can contribute to enhancing the lifetime of the catalysts used in hydrotreating.

[0076] Fig. 2 shows a LWP pretreatment block chart according to an example embodiment. First, a liquefied waste plastic feed (a) is provided. The pretreatment occurs in a first reactor 110. In certain embodiments, said pretreatment comprises mixing the liquefied waste plastic feed with an alkaline aqueous solution to obtain an admixture, and heat-treating said admixture to obtain the pretreated feed (b). In other words, in certain embodiments, the pretreatment is a high-temperature alkaline pretreatment. In certain embodiments, the alkaline is sodium hydroxide, NaOH.

[0077] Following the pretreatment, the pretreated feed (b) is transferred to a phase separation unit 120, wherein a phase separating occurs. Preferably, said phase separating comprises separating an aqueous phase 121 from the pretreated feed (b) to obtain the pretreated oil (c). The aqueous phase 121 comprises the used alkaline.

[0078] In certain embodiments, the pretreated oil (c) is further washed using water to remove alkali residues.

[0079] Following the step of phase separation, the pretreated oil (c) is transferred to a second reactor 130. The adsorbent and the pretreated oil (c) are contacted with each other in the second reactor 130 by dispersing the adsorbent with the pretreated oil (c) to obtain an oiladsorbent admixture. The adsorbent adsorbs the impurities present in the pretreated oil (c).

[0080] Then, the oil-adsorbent admixture (d) is subjected to a solid-liquid separation in a solidliquid separation unit 140 to obtain purified oil (e). The purified oil (e) is recovered.

[0081] The used adsorbent (f) is recovered from the solid-liquid separation unit 140. The used adsorbent preferably comprises impurities and residuals removed from the pretreated oil (c). The used adsorbent (f) is discarded as waste or recycled in any suitable manner or regenerated for any suitable further use.

[0082] In certain embodiments, the aqueous phase 121 separated during the phase separating 120 comprises used alkaline. In certain optional embodiments, at least part of the aqueous phase comprising used alkaline 121 is purified in a purification step 150. In certain optional embodiments, at least a part of the aqueous phase 121 is recycled back to the pretreatment step 110 via stream 123.

[0083] In certain optional embodiments, the purification step 150 comprises a multistep filtration of the aqueous solution comprising the used alkaline. In certain optional embodiments, purification 150 comprises separating the alkaline from non-reusable material, such as dissolved organics. The non-reusable material from the purification step 150, such as the dissolved organics, proceeds to a wastewater treatment 122. In certain embodiments, the wastewater treatment 122 comprises evaporation, followed by separate treatments for distillate and the residue.

[0084] Figs. 3a and 3b show embodiments of the adsorption. Herein is referred to the Fig. 1 , which shows contacting step iv) and solid-liquid separation step v). In certain embodiments, the contacting step iv) followed by a solid-liquid separation step v) comprises a batchwise step. In certain alternative embodiments, the contacting step iv) followed by a solid-liquid separation step v) comprises a continuous step.

[0085] Fig. 3a shows the first step of this embodiment, and Fig. 3b shows the second step of the same embodiment. Referring also to Fig. 2, the contacting step occurs in the second reactor 130 and the solid-liquid separation step occurs in the solid-liquid separation unit 140.

[0086] As shown in Fig. 3a, the pretreated oil (c) is provided into the second reactor 130. The adsorbent 301 is added into the second reactor 130. The adsorbent 301 is contacted with the pretreated oil (c) by dispersing the adsorbent 301 with the pretreated oil (c) to obtain an oil-adsorbent admixture (d).

[0087] The adsorbent 301 is added to the pretreated oil (c) in amount of 0.1 - 20 wt.-% of the total weight of the pretreated oil. In certain embodiments, the step iv) comprises a batchwise step and the adsorbent 301 is added to the pretreated oil (c) in amount of 0.1 - 20 wt.-% of the total weight of the pretreated oil. Optionally, the step iv) comprises heating. Optionally, the step iv) comprises mixing.

[0088] As shown in Fig. 3b, the oil-adsorbent admixture is provided into the solid-liquid separation unit 140. The step v) comprises subjecting the oil-adsorbent admixture (d) to a solid-liquid separation to obtain purified oil (e). In certain embodiments, the step v) comprises separating the adsorbent 301 from the oil-adsorbent admixture (d) to obtain the purified oil (e). In certain preferred embodiments, said separating comprises filtration 302. In certain embodiments, the filtration 302 occurs when removing the purified oil (e) from the solidliquid separation unit 140. In certain embodiments, the used adsorbent 301 remains in the solid-liquid separation unit 140, and the purified oil (e) is recovered using filtration 302.

[0089] According to a second aspect, herein is provided a use of the purified oil obtained from the method according to the first aspect in at least one catalytic hydrotreating step to obtain recycled hydrocarbons.

[0090] The typical way of handling undesirable impurities in feeds is to pretreat the feed prior to hydrotreating. In the context of the present disclosure, hydrotreating is considered as the “main process” for the conversion of the feed into products. Therefore, the treatment(s) with the intention to lower the impurity, such as Na and N content and residual water content in LWP, are beneficial prior to the hydrotreating.

[0091] According to an embodiment of the present use, hydrotreating refers to hydrodeoxygenation, hydrodesulfurisation, hydrodenitrogenation, hydrodehalogenation (such as hydrodechlorination), hydrogenation of double bonds, hydrocracking, hydroisomerisation, any combination thereof, and it also removes some metals. According to an embodiment of the present use, the catalytic hydrotreating comprises one or more of hydrodeoxygenation, hydroisomerisation, hydrocracking, hydrodenitrogenation, hydrodesulfurisation, hydrodehalogenation or hydrogenation of double bonds. According to an embodiment of the present use, the catalytic hydrotreating comprises one or more of the preceding simultaneously or in sequence.

[0092] According to an embodiment of the present use, the catalytic hydrotreating occurs in the presence of a supported catalyst. Preferably, the supported catalyst comprises at least one component selected from IIIPAC group 6, 8 or 10 of the Periodic Table of Elements. More preferably, the supported catalyst comprises Mo and at least one further transition metal on a support, such as a supported NiMo catalyst or a supported CoMo catalyst, wherein the support preferably comprises alumina and / or silica. Even more preferably, the supported catalyst comprises a supported CoMo catalyst, wherein the support comprises alumina (CoMo / AhOa) and / or the supported catalyst comprises NiMo catalyst, wherein the support comprises alumina (NiMo / AI2O3). Said catalysts can lose their activity if impurity compounds form and precipitate thereon. Therefore, removal of impurity compounds, such as metals, Si, and N from the feed to hydrotreating can contribute to enhancing the lifetime of the catalysts used therein .

[0093] Avoiding catalyst deactivation, i.e. the loss over time of catalytic activity and / or selectivity, is a continuing aim in industrial catalytic processes. Costs to industry for catalyst replacement and process shutdown add up into considerable economic losses per year. Time scales for catalyst deactivation may vary considerably depending on the process and the catalyst types used. Some catalysts last for a few seconds whereas some may last for tens of years.

[0094] Typically, the loss of activity and / or selectivity in a well-controlled process occurs slowly. However, process upsets or poorly designed hardware can bring about unexpected and early failures. While catalyst deactivation is inevitable for most processes, some of its drastic consequences may be avoided and at least postponed by the present process and use.

[0095] By deactivation of a catalyst is meant herein the gradual deterioration of the performance of the catalyst, which eventually reaches a level wherein it is no longer reasonable to continue the use of the catalyst. In this context reasonableness is best depicted by the ability to produce the product that fulfills the predefined quality and quantity criteria. In practice this means that each catalyst will confront a point of time when it is deactivated to an extent requiring a change of the spent catalyst to a fresh one. Thus, the deactivation can be described as the catalyst lifetime length per shutdown frequency. This ratio provides a measure for the ability to produce the final product in view of the needed shutdowns for a catalyst change due to deactivation. In other words, less production is lost in a given time frame if there are fewer shutdowns due to catalyst changes originating from catalyst deactivation.

[0096] Deactivation of the catalyst is typically defined as impurities residing on a catalyst surface, thus blocking the active sites of the catalyst from the feedstock molecules. Deactivation of the catalyst may be caused by fouling or poisoning of the catalyst. Fouling is generally considered to be related to deposition of insoluble components present in the feed or formed by degradation of the feed or reaction intermediates, whereas poisoning is related to the deposition of electropositive contaminants, such as alkali and alkaline earth metals, on acid sites or electronegative contaminants at hydrogenation sites.

[0097] Using the method according to the first aspect the catalyst deactivation is minimized in the following process steps due to the enhanced impurity and residual removal. The impurities and residuals that remain present in the pretreated oil are removed in the adsorption to obtain a purified oil. This results in a high-quality purified oil to be used as a raw material in the following processes in the refinery. Accordingly, in the use according to the second aspect catalyst deactivation is minimized due to utilization of the purified oil from the method according to the first aspect as a raw material in the following processes in the refinery.

[0098] According to a third aspect, herein is provided a use of high temperature pretreatment and adsorption sequentially for purifying liquefied waste plastic. Preferably, the high temperature pretreatment comprises high temperature alkaline pretreatment. Preferably, the high temperature pretreatment comprises mixing the liquefied waste plastic feed with an aqueous solution to obtain an admixture, and heat-treating said admixture to obtain the pretreated feed. Preferably, the high temperature pretreatment is followed by a phase separating the pretreated feed to obtain a pretreated oil. Preferably, the adsorption comprises contacting an adsorbent with the pretreated oil by dispersing the adsorbent with the pretreated oil to obtain an oil-adsorbent admixture. Preferably, the adsorption is followed by subjecting the oil-adsorbent admixture to a solid-liquid separation to obtain a purified liquefied plastic oil. According to an embodiment, the adsorption comprises adsorption via porous adsorbent. According to an embodiment, the adsorption comprises adsorption via dry adsorbent.

[0099] The use according to the third aspect enables providing high-quality purified LWP oils. The use according to the third aspect enhances the impurity- and residual removal in liquefied waste plastic purifying processes.

[0100] In accordance with certain embodiments, embodiments of the first, second and third aspect are provided, the embodiments comprising subject matter of any single embodiment presented in connection with the first, second or third aspect, or the embodiments comprising subject matter of any of the embodiments presented in connection with the first, second or third aspect combined with subject matter presented in any other embodiment or embodiments. Any embodiment presented in connection to the first aspect is combinable / applicable to any of the embodiments presented in connection to the second or the third aspect as well. The same applies to the second aspect and to the third aspect as well.

[0101] EXAMPLES

[0102] The following examples are provided to better illustrate the claimed invention and are not to be interpreted as limiting the scope of the invention. To the extent that specific materials are mentioned, it is merely for purposes of illustration and is not intended to limit the invention.

[0103] Example 1

[0104] The purification via adsorption of LWPs according to the present method was experimented. When referring to a certain specific impurity, it should be understood in the context of the present example to comprise also any derivatives, ions, or salts thereof possibly also present in the samples.

[0105] First, the liquefied waste plastic feed (LWP feed) was pretreated via high-temperature alkaline pretreatment in a continuous tubular reactor to obtain a pretreated feed. Said high- temperature alkaline pretreatment was conducted in an analogous manner with the Example 4 of W02020016400A1 .

[0106] The alkaline compound used in the pretreatment was sodium hydroxide (NaOH). The pretreating comprised providing separate streams of the LWP feed and the aqueous NaOH solution, and mixing them via in-line mixing before the heat treatment reactor to form an admixture. The feeding rate of each stream was controlled to obtain a specific water-to-oil ratio on a weight basis. Then, said admixture was heat-treated in the heat treatment reactor at a specific temperature for a specific residence time. The liquefied waste plastic feed was pretreated under the process conditions of:

[0107] - temperature T = 280 °C residence time = 60 min water-to-oil ratio = 0.3 (weight of aqueous NaOH solution I weight of oil) alkaline concentration (NaOH) = 3 wt.-% of the aqueous solution.

[0108] The pretreatment enables removing inorganic and organic impurities or derivatives thereof from LWP feed by converting them into water-soluble forms which enables them to be extracted into the aqueous phase.

[0109] After the high-temperature alkaline pretreatment, the phase separation was performed to obtain a pretreated oil (SampleO). The aqueous phase was separated from the pretreated feed via settling.

[0110] The results of the pretreatment (and phase separation) are shown in Table 1. Table 1. The pretreatment (and phase separation) results.

[0111] The methods in the far-left column are described in more detail herein. The ASTME203 refers to an international standard ASTM E203: Standard Test Method for Water Using Volumetric Karl Fischer Titration. The ASTMD5762 refers to an international standard ASTM D5762: Standard Test Method for Nitrogen in Liquid Hydrocarbons, Petroleum and Petroleum Products by Boat-Inlet Chemiluminescence.

[0112] The method IPC-MS / MS refers to a measurement of Na, Si and P content by tandem inductively coupled plasma-mass spectrometry (ICP-MS / MS). It is digested with acids in a microwave oven to a clear water / acid matrix, diluted to a known amount and analysed against the acid-based calibration using ICP-MS / MS.

[0113] The method IC refers to the measurement of chlorine content using ion chromatography. In this method, the sample is combusted in a combustion vessel and the anions are absorbed into the water. The anions of the sample are separated in an ion chromatographic column and detection is carried out using a conductivity detector.

[0114] As shown in Table 1 , the Na content of LWP feed increased remarkably during the pretreatment of the liquefied waste plastic feed. The Na content before the pretreatment in the original liquefied waste plastic feed was 0.68 mg / kg and the Na content after the pretreatment in the pretreated oil was 31 mg / kg. The increase of Na content of the pretreated oil has been observed when the aqueous alkaline condition of the pretreatment has been used to pretreat the LWP feed. This observation is applicable also to other metal hydroxides such as Li, and K, when they have been used to provide the necessary alkaline aqueous condition. The increase of Na content of the pretreated oil was considered to be an unsatisfactory result from the phase separation between the oil and aqueous phases in the phase separating step, where it is unfavorable to have any metal ions present in the pretreated oil as the pretreated oil is intended to be used for downstream processing such as hydrotreating. However, as shown in Table 1 , this negative change in the LWP quality (the increase of NA content) occurred in parallel to several improvements. Even though the Na content increased during pretreatment, the chlorine, Cl, content of the pretreated oil decreased from 420 mg / kg to 23 mg / kg and the nitrogen, N, content of the pretreated oil from 1800 mg / kg to 1100 mg / kg as shown in Table 1.

[0115] Pretreatment and phase separation are the primary ways of decreasing the Cl content of the pretreated oil since the adsorption does not essentially decrease the Cl content further. On the other hand, the N content is further decreased during the adsorption, which will be shown later in this example.

[0116] Then, the pretreated oil (SampleO) was placed at room temperature overnight before adsorption experiments. In this example, the selected adsorbent was a porous adsorbent, specifically silica, more specifically synthetic amorphous silica. Prior to adsorption experiments, silica was pre-dried at 120 °C overnight. Two samples using non-dried silica were taken as a reference group. The dried silica lost approximately 40 % of its original weight during the drying process.

[0117] 100 g pretreated oil (SampleO) with either 0.6 g or 6 g dried silica (meaning 0.6 or 6 wt.-%) were introduced into glass bottles and placed on a tube shaker at low speed (30 rpm) for times spanning from 1 h up to 168 h at room temperature. In the reference group, two samples used 6 g non-dried silica (meaning 6 wt.-%) for 24 and 72 h and other processing parameters remained constant.

[0118] For the separation after the adsorption test, 0.45 pm filtration paper was used to filter off the used silica. For 0.6 wt.-% silica, the mere filtration was sufficient, but to filter off 6 wt.-% silica the combination of centrifugation at room temperature and said filtration was used.

[0119] Table 2 shows the adsorption test results for 0.6 wt.-% dried silica (Samples 1-4), in which the residence time varied from 1 h up to 168h. Table 3 shows the adsorption test results for 6 wt.-% dried silica (Samples 5-6) and 6 wt.-% non-dried silica (Ref 1-2), in which the residence time varied from 24h up to 72h. Table 2. The adsorption test results for 0.6 wt.-% dried silica.

[0120] Table 3. The adsorption test results for 6 wt.-% dried silica and 6 wt.-% non-dried silica.

[0121] Tables 2 and 3 show that Na and water (H2O) are effectively removed from all samples in the adsorption tests. The removal efficiency of Na and water persists even when using 0.6 wt.-% of silica (Samples 1-4), as well as even when using shortest residence time (1 h, Sample 1 ). Longer adsorption time did not improve the removal rates of Na or water. The water removal efficiency in the reference group with 6 wt.-% non-dried silica (Refs 1-2) is also remarkable. This indicates the strong water adsorption of silica, either dried or nondried in the pretreated oil.

[0122] Interestingly, substantial amounts of N are reduced from the pretreated oil when utilizing 6 wt.-% dried silica (Samples 5-6) as shown in Table 3.

[0123] Table 3 shows that 6 wt.-% dried silica (Samples 5-6) is able to reduce a substantial amount of Si from the pretreated oil. Table 2 shows that 0.6 wt.-% dried silica (Samples 1-4) is able to remove a fair amount of Si from the pretreated oil, but slightly less than 6 wt.-% dried silica (Samples 5-6). Table 3 shows that 6 wt.-% non-dried silica (Refs 1-2) is also able to remove a fair amount of Si from the pretreated oil, but slightly less than 6 wt.-% dried silica (Samples 5-6). The extended adsorption time did not enhance the efficiency of Si removal.

[0124] The adsorption results shown in Tables 2 and 3 demonstrate that Na is readily captured by silica pores. Further, water (H2O) has a strong affinity to silica. Yet further, Si and N interact with the hydroxyl groups of silica and / or diffuse in the appropriate pores of which efficiencies are significantly influenced by the water content in silica as well as the silica amount in LWPs. The dried silica appears to remove the impurities tested in this Example better in comparison to the non-dried silica.

[0125] Accordingly, silica can be used in Na, N and H2O removal in the pretreated LWPs after the pretreatment, such as after the high-temperature alkaline pretreatment. The best results are achieved with a relatively high amount of dried silica.

[0126] Accordingly, the present method according to the first aspect provides high quality pretreated oils, due to improved impurity removal, preferably Na and N removal, as well as improved residual water H2O removal. The impurity and residual water removal is performed via adsorption using an adsorbent after pretreatment. The present method produces high quality purified LWP oils, which may be used as further raw materials in the following processes in the refinery. The purification of these oils reduces catalyst deactivation in the following process steps in the refinery. Furthermore, the harmful precipitation of the impurities in the purified oil is minimal. Also, better pumpability and filterability are enabled in the following process steps in the refinery. This reduces the need for process interruptions dedicated to cleaning fouled equipment.

[0127] The same above-mentioned benefits apply also to use according to the second aspect, as well as to the use according to the third aspect. The present method of purifying LWPs may be incorporated to the existing LWP refining facilities. Thus, the present method may find use in existing processes, but also in newly established processes.

[0128] Various embodiments have been presented. It should be appreciated that in this document, words comprise, include, and contain are each used as open-ended expressions with no intended exclusivity. The foregoing description has provided by way of non-limiting examples of particular implementations and embodiments a full and informative description of the best mode presently contemplated by the inventors for carrying out the invention. It is however clear to a person skilled in the art that the invention is not restricted to details of the embodiments presented in the foregoing, but that it can be implemented in other embodiments using equivalent means or in different combinations of embodiments without deviating from the characteristics of the invention. Furthermore, some of the features of the afore-disclosed example embodiments may be used to advantage without the corresponding use of other features. As such, the foregoing description shall be considered as merely illustrative of the principles of the present invention, and not in limitation thereof. Hence, the scope of the invention is only restricted by the appended patent claims.

Claims

CLAIMS1 . A method for purifying liquefied waste plastic, LWP, the method comprising the steps of i) providing a liquefied waste plastic feed (a); ii) pretreating the liquefied waste plastic feed (a) to obtain a pretreated feed (b), wherein the pretreating comprises mixing the liquefied waste plastic feed (a) with an aqueous solution to obtain an admixture, and heat-treating said admixture to obtain the pretreated feed (b); iii) phase separating the pretreated feed (b) to obtain a pretreated oil (c); iv) contacting an adsorbent with the pretreated oil (c) by dispersing the adsorbent with the pretreated oil (c) to obtain an oil-adsorbent admixture (d); and v) subjecting the oil-adsorbent admixture (d) to a solid-liquid separation to obtain purified oil (e).

2. The method according to claim 1 , wherein the aqueous solution is alkaline.

3. The method according to claim 1 or 2, wherein the step iii) of phase separating comprises separating an aqueous phase from the pretreated feed (b) to obtain the pretreated oil (c).

4. The method according to any one of the preceding claims, wherein the adsorbent comprises a porous adsorbent.

5. The method according to any one of the preceding claims, wherein the adsorbent comprises a dry adsorbent.

6. The method according to any one of the preceding claims, wherein the adsorbent is in particulate form.

7. The method according to claim 6, wherein adsorbent has average particle size d50 of the particulate about 25000 pm or less, preferably about 6500 pm or less, more preferably about 2000 pm or less, most preferably about 500 pm or less, such as about 50 pm or less.

8. The method according to any one of the preceding claims, wherein the adsorbent comprises a solid sorption agent selected from the list comprising activated carbon, alumina, silica, clay materials, zeolites, ion exchange resins, absorbent organic polymers or a combination thereof, preferably the adsorbent comprises a solid sorption agent selected from the list comprising silica gel, clay, crushed clay, apatite, hydroxyapatite and combinations thereof, an alumina, such as an alumina obtainedby precipitation of boehmite, a calcined alumina, boehmite, bayerite, hydrotalcite, a spinel, a promoted alumina, an acid promoted alumina, an alumina promoted by a zeolite and / or by a metal such as Ni, Co, Mo or a combination of at least two of them, a clay treated with an acid, a molecular sieve in the form of an aluminosilicate containing an alkaline or alkaline-earth cation, such as the 3A, 4A, 5A, 13X sieves, or a molecular sieve, a zeolite, an activated carbon, or the combination thereof.

9. The method according to any one of the preceding claims, wherein the step iv) comprises a batchwise step and the adsorbent is added to the pretreated oil (c) in amount of 0.1 - 20 wt.-% of the total weight of the pretreated oil.

10. The method according to any one of the preceding claims, wherein the step iv) is carried out at a temperature between 25 °C and 150 °C.11 . The method according to any one of the preceding claims, wherein the step iv) further comprises subjecting the oil-adsorbent admixture to agitation in a mixing vessel.

12. The method according to any of the preceding claims, wherein the step iv) comprises reducing the amount of at least one impurity selected from F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg, Hg, and / or derivatives, ions or salts thereof, and / or the H2O content of the pretreated oil (c) by contacting the adsorbent with the pretreated oil (c) by dispersing the adsorbent with the pretreated oil (c), preferably reducing the amount of at least one impurity selected from N, Na, and / or derivatives, ions or salts thereof, and / or the H2O content of the pretreated oil (c) by contacting the adsorbent with the pretreated oil (c) by dispersing the adsorbent with the pretreated oil (c).

13. The method according to any of the preceding claims, wherein in the step iv) the adsorbent adsorbs at least 20 wt.-% of the total weight of the impurities, preferably at least 50 wt.-% of the total weight of the impurities of at least one impurity selected from F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg, Hg, and / or derivatives, ions or salts thereof, and / or the H2O, preferably of at least one impurity selected from N, Na, and / or derivatives, ions or salts thereof and / or the H2O.

14. The method according to any one of the preceding claims, wherein the step v) of solidliquid separation comprises filtration, centrifugation, settling or a combination thereof.

15. The method according to any of the preceding claims, wherein the step v) comprises subjecting the oil-adsorbent admixture (d) to the solid-liquid separation to separate the adsorbent from the oil-adsorbent admixture (d) to obtain the purified oil (e)having a reduced amount of at least one impurity selected from F, Cl, Br, I, O, N, S, Se, Si, P, As, Fe, Ca, Na, K, Mg, Hg, and / or derivatives, ions or salts thereof, and / or the H2O content in relation to the pretreated oil (c), preferably having a reduced amount of at least one impurity selected from N, Na, and / or derivatives, ions or salts thereof, and / or the H2O content in relation to the pretreated oil (c).

16. The method according to any one of the preceding claims, wherein the purified oil (e) has a moisture content of 0.05 wt.-% or less of the total weight of the purified oil.

17. Use of the purified oil (e) obtained from the method according to any of the claims 1-16 in at least one catalytic hydrotreating step to obtain recycled hydrocarbons.

18. The use according to claim 17, wherein the catalytic hydrotreating comprises one or more of hydrodeoxygenation, hydroisomerisation, hydrocracking, hydrodenitrogenation, hydrodesulfurisation, hydrodehalogenation or hydrogenation of double bonds.

19. The use according to claim 17 or 18, wherein the catalytic hydrotreating occurs in the presence of a supported catalyst, the supported catalyst preferably comprising at least one component selected from IUPAC group 6, 8 or 10 of the Periodic Table of Elements, the supported catalyst more preferably comprising Mo and at least one further transition metal on a support, such as a supported NiMo catalyst or a supported C0M0 catalyst, wherein the support preferably comprises alumina and / or silica, even more preferably the supported catalyst comprising a supported C0M0 catalyst, wherein the support comprises alumina (CoMo / AhOa) and / or the supported catalyst comprising NiMo catalyst, wherein the support comprises alumina (NiMo / AI2O3).

20. Use of high temperature pretreatment and adsorption sequentially for purifying liquefied waste plastic.21 . The use according to claim 20, wherein the high temperature pretreatment comprises high temperature alkaline pretreatment.

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