FIELD OF THE INVENTION

The present invention relates to a method for producing purified fractions of a liquid crude pyrolysis oil from a hydrocarbon based waste plastic comprising polyolefins and heteroatom -based contaminants, in particular polyethylene terephthalate (PET). The present invention further relates to the products obtained by this method and their use for manufacturing high-value chemical products.

BACKGROUND OF THE INVENTION

Crude oil is a primary source of energy, and oil refining is an important aspect of the global energy system. Despite the fact that crude oil is an extremely complex and dirty material with a multitude of molecular families and contaminants, its value resides in the direct conversion of crude oil to fuels and high-value chemical products. This conversion can be realized by first subjecting the crude oil to some primary steps using different technologies such as distillation, extraction, cracking, and combinations thereof. This results in first line materials such as naphtha, fuel, lubes, and waxes. Afterwards, a further upgrading to chemicals is possible by “classical” petrochemical processes. It should be mentioned that for a lot of these primary steps tight specifications are set. For example, the feedstock for naphtha cracking should only contain very small amount of polar substances including oxygenates, such as ethers, ketones, and aldehydes, in order to avoid destruction of the process catalysts. To solve this problem, deheterogenation, e.g. deoxygenation and denitrogenation on crude oil and/or fractions thereof, in particular on naphtha, is conventionally done by hydrotreatment. However, this hydrotreatment involves the use of hydrogen (H2) at high temperatures and pressures, thus the need of an expensive installation and related equipment. In other words, such hydrotreatment is complex and very specialized.

Another way to successfully arrive at fuels and chemicals is starting from primary chemical building blocks. For example, in the syngas based Fischer-Tropsch and related processes, CO and Fte, which can be obtained from the gasification of coal or the reforming of natural gas, are combined to produce a mixture of hydrocarbons. When such hydrocarbon streams are used as input for crackers or for other petrochemical processes, the amount of oxygenates present should also be low.

For example, WO 2004/080927 discloses a process for extracting oxygenates, such as alcohols, esters, aldehydes, and ketones from a hydrocarbon stream, which is a lighter fraction of the condensation product of a Fischer-Tropsch reaction, in particular a low temperature Fischer-Tropsch reaction. This fraction, typically containing paraffins in the C4 to C26 range, oxygenates in an amount varying from 5 - 15 wt. % and having a low olefin content, is ideal for the production of alkylbenzene. Flowever, oxygenates, having a negative effect on alkylation reactions, have to be removed by extraction, in particular by a liquid-liquid extraction. Prior to this extraction, the lighter fraction is first fractionated into a C10 -C13 cut. The aim of this extraction process is to preserve the olefin content in order to be useful in the production of linear alkylbenzene.

In addition to the above, waste plastic pyrolysis oils and/or fractions thereof, especially pyrolysis oils originating from polyolefin-rich feedstock, also have a lot of potential in order to be upgraded to valuable products: e.g. chemical raw materials such as naphtha, oil/lubricants, wax. Additionally, precious chemicals can be obtained due to the presence of a lot of unsaturated compounds having double bonds, in particular terminal double bonds (i.e. terminal alkenes). Especially, the terminal double bonds are interesting active sites for functionalization chemistry. Flowever, the drawback of the presence of terminal alkenes is that the pyrolysis oil and/or fractions thereof tends to gel over time due to (addition) polymerization reactions, radical reactions, and the like, said reactions being catalyzed by various impurities of different nature present in the pyrolysis oil. Industrial waste plastic material is also known to be very heterogeneous, contaminated, out of specification, and comprises different materials. Hence, the resulting pyrolysis oil, in particular of waste polyolefins, and/or fractions thereof are very different in nature than the crude oil and/or fractions thereof. The oxygen and nitrogen compounds in such waste plastic pyrolysis oils are very specific and completely different from those as present in crude oil. Major sources of them are food contaminants (e.g. sugars, fats, cellulose), other type of plastics (e.g. polyamides, polyesters such as PET, halogenated polymers such as PVC and the like), additives (e.g. colorants, softeners, release agents), and decomposition side reaction products resulting notably from Maillard reactions. Therefore, the heterogenates are not only low boiling compounds but a significant amount of the oxygenates and nitrogenates are high boiling compounds such as benzoic acid (boiling point = 250 °C), caprolactam (boiling point = 270 °C), etc. The methods for deoxygenation and denitrogenation known in the art and applied in the case of crude oil are not efficient nor working. Hydrotreatment of waste plastic pyrolysis oils and/or fractions thereof will result in major disadvantages. Namely, the need of a much higher amount of hydrogen (H2) due to large amounts of double bond unsaturations that consume the added hydrogen via the saturation side reactions at the used temperature and pressure. As a consequence, the chemically interesting terminal double bonds will disappear under the conditions of hydrotreatment. Thus, functionalization afterwards will be much more complex in the absence of these double bond active sites. In other words, hydrotreatment of waste plastic pyrolysis oils and/or fractions thereof, in particular originating from polyolefin waste plastics, is a very uneconomical and illogical approach.

Therefore, there is thus a need for a new method for producing purified fractions of a liquid crude pyrolysis oil from a hydrocarbon waste plastic, whereby said purified fractions are stable upon standing without any fouling, whereby said fractions are substantially free from low boiling heterogenates and high boiling heterogenates in order to avoid poisoning of catalysts for instance during naphtha cracking or influencing the polarities of resulting hydrophobic waxes, and whereby these deheterogenated fractions maintain high amounts of unsaturated compounds having double bonds, in particular terminal double bonds (i.e. terminal alkenes) thereby enabling further valorization of these deheterogenated fractions into valuable chemicals via the use of functionalization chemistry.

SUMMARY OF THE INVENTION

The inventors have now surprisingly found that it is possible to provide a new method fulfilling the above-mentioned needs.

Thus, there is now provided a method for producing at least one purified pyrolysis oil fraction from a hydrocarbon based waste plastic comprising polyolefins and heteroatom-based contaminants, which method comprises the steps of:

Step 1 : pyrolyzing the hydrocarbon based waste plastic to produce a gaseous pyrolysis product comprising at least saturated hydrocarbons, unsaturated hydrocarbons, and contaminants including heterogenates; Step 2: at least partially condensing the gaseous pyrolysis product to produce at least one liquid pyrolysis oil fraction;

Step 3: purifying the at least one liquid pyrolysis oil fraction by removing at least a portion of the heterogenates contained therein by a liquid extraction process and/or a liquid-solid adsorption process and/or a precipitation process to produce at least one purified pyrolysis oil fraction. DETAILED DESCRIPTION

The term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It needs to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a method comprising the steps A and B” should not be limited to the method consisting only of steps A and B. It means that with respect to the present invention, the only relevant steps of the method are A and B. Accordingly, the terms “comprising” and “including” encompass the more restrictive terms “consisting essentially of” and “consisting of”.

As used herein, the terms "optional" or "optionally" means that a subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

Within the context of the present invention, a hydrocarbon based waste plastic is intended to refer to a mixture of plastic waste in general as obtained by collection and handling, an industrial waste plastic material such as plastic materials out of specification, plastic materials related to pre- and post runs, plastic materials related to cleaning runs, and the like, a post-consumer waste plastic material such as a private household waste plastic material, and mixtures of the above. Preferably, the hydrocarbon based waste plastic is a household waste plastic material.

As said, according to the present invention, the hydrocarbon based waste plastic comprises polyolefins and heteroatom-based contaminants.

In general, polyolefins are known to the skilled person in the art. A polyolefin is a polymer produced from an olefin or alkene as a monomer. Non limiting examples of such polyolefins notably include polypropylene (PP), polyethylene (PE) such as HDPE and LDPE, polymethylpentene (PMP), polybutene (PB), ethylene-octene copolymers, ethylene propylene rubber (EPR), ethylene propylene diene monomer rubber (EPDM rubber), poly(buta- 1, 3-diene), and copolymers thereof.

As used herein, heteroatoms comprised in the heteroatom-based contaminants notably refer to oxygen, nitrogen, and/or sulphur atoms. Non limiting examples of heteroatom -based contaminants notably include food contaminants (e.g. sugars, fats, cellulose), additives typically used in polymeric materials and/or present in finished products, e.g. labelled packaging material (e.g. inorganic and/or organic fillers, flame retardants, pigments, plasticizers, colorants, softeners, inks, papers, glues, release agents), and the like.

According to the method of the present invention, the hydrocarbon based waste plastic may further comprise other polymers, such as notably polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamides (PA), polyoxymethylene (POM), polyepoxides (epoxy resins), acrylonitrile butadiene styrene (ABS), poly(methyl methacrylate) (PMMA), polyurethane (PUR), and the like. In particular, the hydrocarbon based waste plastic originating from drinking (water) bottles, food packaging and construction materials often comprises PET.

As to the amount of polyolefins comprised in the hydrocarbon based waste plastic, polyolefins are preferably present in an amount equal to or greater than 80 wt. %, more preferably equal to or greater than 90 wt. %, even more preferably equal to or greater than 95 wt. %, relative to the total dry weight of the hydrocarbon based waste plastic.

As to the amount of PET comprised in the hydrocarbon based waste plastic, PET is preferably present in an amount equal to or less than 15.0 weight percentage [wt. %, herein after], more preferably equal to or less than 10.0 wt. %, even more preferably equal to or less than 5.0 wt. %, relative to the total dry weight of the hydrocarbon based waste plastic.

According to the method of the present invention, the hydrocarbon based waste plastic may further comprise other polymers, such as notably chlorinated polymers (i.e. chlorinated polyethylene, polyvinylchloride (PVC), polyvinylidene chloride (PVDC)), polytetrafluoroethylene (PTFE), and the like, and metals such as aluminium as for instance in beverage cartons comprising polyal and the like.

As said, according to Step 1 of the method of the present invention, the hydrocarbon based waste plastic, as detailed above, is first pyrolyzed thereby producing a gaseous pyrolysis product, said gaseous pyrolysis product comprising at least saturated hydrocarbons, unsaturated hydrocarbons, and contaminants including heterogenates.

In chemical recycling, pyrolysis refers to a thermal or catalytic pyrolysis in an oxygen free or limited oxygen environment, whereby the catalytic pyrolysis means a pyrolysis in the presence of one or more catalysts such as metal oxide and metal carbonate catalysts (e.g. calcium oxide, barium oxide, potassium oxide, magnesium carbonate, calcium carbonate, etc.). In general, during pyrolysis, the chemical structure of the polymers comprised in the hydrocarbon based waste plastic, as detailed above, is altered and these polymers may undergo depolymerization reactions, cracking reactions, decomposition reactions, or a combination thereof. Apart from these reactions, also numerous side reactions of reactive species can occur during pyrolysis of the hydrocarbon based waste plastic in a pyrolysis reactor, whereby said reactive species originate or are derived from the polyolefins and/or the heteroatom -based contaminants as comprised in the hydrocarbon based waste plastic.

In general, known pyrolysis reactors in the art can be used for pyrolyzing the hydrocarbon based waste plastic thereby producing the gaseous pyrolysis product. Non-limiting examples of such pyrolysis reactors notably include a fixed bed flow reactor, a fluidized bed reactor, an entrained bed reactor, an Auger/screw pyrolysis reactor, a continuous stirred-tank pyrolysis reactor, and the like. Preferably, the pyrolysis reactor is a continuous stirred- tank pyrolysis reactor. ln Step 1 of the method of the present invention, the hydrocarbon based waste plastic can be pyrolyzed under optimal temperature and pressure conditions with the aim to maximize the yield and nature of the condensable fraction of the gaseous pyrolysis product. In particular, the temperature and pressure for pyrolyzing the hydrocarbon based waste plastic in Step 1 may be selected in such a way to produce gaseous pyrolysis products comprising heterogenates, saturated and unsaturated hydrocarbons having a chain length, which can vary as from Ci to C40 or even higher, in which either a middle, i.e. an intermediate molecular weight, fraction of saturated and unsaturated hydrocarbons having a chain length from C6 to C28 (i.e. liquid fraction at room temperature) or a higher fraction of saturated hydrocarbons and unsaturated hydrocarbons having a chain length from C28 to C40 (i.e. a (semi-)solid fraction at room temperature) can be present.

According to certain embodiments in Step 1 of the method of the present invention, the hydrocarbon based waste plastic is pyrolyzed at a temperature from 300 °C to 650 °C, preferably from 400 °C to 600 °C, preferably from 450 °C to 550 °C.

According to certain embodiments in Step 1 of the method of the present invention, the hydrocarbon based waste plastic is pyrolyzed at a pressure from 0.1 bara to 10.0 bara, preferably from 0.3 bara to 5.0 bara, more preferably from 0.5 bara to 2.0 bara.

In general, in Step 1 of the method of the present invention, as detailed above, a solid residue, i.e. a residue which is solid, is left in the pyrolysis reactor. This solid residue may comprise non-pyrolyzable solids contained in the hydrocarbon based waste plastic, and carbon (char) produced by the pyrolysis of the hydrocarbons contained in the hydrocarbon based waste plastic. The non-pyrolyzable solids may particularly include (1) inorganic substances such as fillers, pigments, and impurities such as sands and salts; and also (2) aluminium as for instance comprised in polyal. An advantage of producing only a gaseous pyrolysis product is that said product is immediately free of (1) the non-pyrolyzable solids which were already present in the hydrocarbon based waste plastic, as detailed above; and (2) carbon (char) produced by the pyrolysis of the hydrocarbons contained in the hydrocarbon based waste plastic. Moreover, the gaseous pyrolysis product is also free of hydrocarbon based waste plastic and/or polymers contained therein which have not yet been pyrolyzed sufficiently. The production of the gaseous pyrolysis product also enables the preferable use of continuous stirred-tank pyrolysis reactors wherein the hydrocarbon based waste plastic is continuously fed and from which said gaseous pyrolysis product is continuously removed.

As said, according to Step 2 of the method of the present invention, the gaseous pyrolysis product comprising at least saturated hydrocarbons, unsaturated hydrocarbons, and contaminants including heterogenates, as detailed above, is at least partially condensed thereby producing at least one liquid pyrolysis oil fraction.

Within the context of the present invention, the term “liquid pyrolysis oil fraction” is intended to denote any condensed pyrolysis oil fraction as obtained after at least partially condensing the gaseous pyrolysis product, as detailed above, said condensed pyrolysis oil fraction comprising heterogenates, saturated and unsaturated hydrocarbons having a chain length, which can vary as from C6 to C40 or even higher, or any intermediate fraction thereof. It is further understood that the liquid pyrolysis oil fraction can be liquid or (semi- )solid at room temperature.

Within the context of the present invention, the term “room temperature” is intended to denote a temperature of 20 °C.

Within the context of the present invention, a liquid pyrolysis oil fraction being liquid at room temperature is characterized by having a viscosity equal to or lower than 200 mPa.s, as measured by using a HAAKE, RheoStress RS1 using a parallel plate geometry with PP60 plates, a gap of 0.5 mm, the measurement being performed at room temperature in oscillatory mode at a frequency 1 Hz and with an amplitude of 0.05 rad. Non-limiting examples of a liquid pyrolysis oil fraction being liquid at room temperature notably include naphtha fraction, and gasoline fraction.

Within the context of the present invention, a liquid pyrolysis oil fraction being (semi-)solid at room temperature is characterized by having a viscosity greater than 200 mPa.s, as measured by using a HAAKE, RheoStress RS1 using a parallel plate geometry with PP60 plates, a gap of 0.5 mm, the measurement being performed at room temperature in oscillatory mode at a frequency 1 Hz and with an amplitude of 0.05 rad. Non-limiting examples of a liquid pyrolysis oil fraction being (semi-)solid at room temperature notably include drilling grease, lubricating soft wax, floor wax, and slack wax.

It is furthermore understood that the state of matter of the liquid pyrolysis oil fraction is temperature dependent.

Within the context of the present invention, the expression “at least one liquid pyrolysis oil fraction” is intended to denote one or more than one liquid pyrolysis oil fraction.

The at least partial condensation of the gaseous pyrolysis product can be carried out by known methods in the art such as by using a quencher to which said gaseous pyrolysis product can be fed via a pipe. For example, the gaseous pyrolysis product of Step 1 can be cooled down in one step thereby producing one liquid pyrolysis oil fraction or successively cooled in several steps at different temperatures thereby producing more than one liquid pyrolysis oil fraction. In general, the at least partial condensation of the gaseous pyrolysis product can be performed at different temperatures and pressures.

The expression “at least partially” is used here since the gaseous pyrolysis product as obtained in Step 1 will normally contain non-condensable products, i.e. gases, such as for instance one or more Ci to Cs gases, which will not be condensed when the gaseous pyrolysis product is cooled down, at atmospheric pressure, to a temperature of about 40 °C. It goes without saying that if the condensing is carried out at other pressures than atmospheric pressure, the corresponding temperatures need to be determined accordingly in order to ensure that the non-condensable products, i.e. gases, for instance having a boiling point at atmospheric pressure of lower than 50 °C, remain in the gaseous phase (i.e. Ci to Cs gases).

According to a preferred embodiment in Step 2 of the method of the present invention, the gaseous pyrolysis product, as detailed above, is cooled down, at atmospheric pressure, to a temperature ranging from 10 °C to 60 °C, preferably from 20 °C to 40 °C thereby producing a liquid pyrolysis oil fraction containing heterogenates, saturated and unsaturated hydrocarbons having a chain length, which can vary as from C6 to C40 or even higher (depending on the desired end product).

The non-condensable gases, such as for instance one or more Ci to Cs gases, can then be removed for instance via a pipe as connected to a storage tank of an incinerator device.

If desired, the gaseous pyrolysis product, as detailed above, can be cooled down, at atmospheric pressure, to temperatures far below 40 °C with the aim to condense as well Ci to Cs gases. However, this is less preferred since this would lower the flash point of the liquid fraction thereby requiring additional security measures.

According to another embodiment in Step 2 of the method of the present invention, the gaseous pyrolysis product, as detailed above, is subjected to a fractional partial condensation. In particular, the gaseous pyrolysis product, as produced in Step 1, can first be cooled down, at atmospheric pressure, to a temperature ranging from 0 °C to 200 °C, preferably from 20 °C to 150 °C thereby producing a first liquid pyrolysis oil fraction containing high boiling heterogenates, saturated and unsaturated hydrocarbons having a chain length which can vary as from C28 to C40 or even higher (depending on the desired end product) and a second gaseous fraction containing low boiling heterogenates, saturated and unsaturated hydrocarbons having a chain length, which can vary as from Ci to C28. Said second gaseous fraction can then be cooled down, at atmospheric pressure, to a temperature ranging from 10 °C to 60 °C, preferably from 20 °C to 40 °C thereby producing a second liquid pyrolysis oil fraction containing low boiling heterogenates, saturated and unsaturated hydrocarbons having a chain length, which can vary as from OQ to C28 or even higher (depending on the desired end product).

The one or more liquid pyrolysis oil fractions as produced in Step 2 of the method of the present invention may suffer some problems of instability which notably may occur through the filming and gelling of said liquid pyrolysis oil fractions upon standing in time in combination with fouling thereby forming a so called tar fraction.

Within the context of the present invention, the term “fouling” refers to depositions of dark coloured and tacky particles of tar products, filming and gelling material, and heterogenates on the surfaces of vessels and/or distillation columns upon further processing of the at least one liquid pyrolysis oil fraction. This fouling can be due to substances already present in the condensed fractions and/or by ongoing chemical polymerization reactions as unsaturated molecules are present.

As to the amount of the tar fraction, said tar fraction is in general present in an amount less than 10.0 wt. %, or less than 5.0 wt. %, or less than 2.0 wt. %, relative to the total weight of the at least one liquid pyrolysis oil fraction.

Suitable processes for removing such tar fraction, notably include filtration, bottom flash distillation in order to separate a single gaseous phase from the tar fraction for instance at a temperature higher than 500 °C when expressed at atmospheric pressure or at a lower corresponding temperature when applying underpressure, or by using a thin film evaporator, optionally by applying underpressure. Preferably, the tar fraction is removed from the at least one liquid pyrolysis oil fraction, as produced in Step 2, by using a thin film evaporator applying underpressure. Within the context of the present invention, the heterogenates comprised in the at least one liquid pyrolysis oil fraction, as produced in Step 2, may include a wide variety of oxygenates, and/or nitrogenates, and optionally halogenates depending on the nature of the hydrocarbon based waste plastic, the pyrolysis conditions (i.e. temperature and pressure used), condensation conditions, fractionations that are performed, etc.

Non-limiting examples of such heterogenates are organic compounds, including aliphatic and aromatic ketones, aliphatic and aromatic alcohols, aliphatic and aromatic ethers, aliphatic and aromatic aldehydes, aliphatic and aromatic carboxylic acids, aliphatic and aromatic amides, aliphatic and aromatic nitriles and the like, in particular mention may be made of n- hexadecanoic acid, benzoic acid, 4-methylbenzoic acid, 4-ethylbenzoic acid, phthalic acids, caprolactam, phenol, 4-phenylbutanenitrile, 2- phenylpropanenitrile, 1 ,2-dimethoxybenzene 2,4-xylenol, acetophenone, 2- methylfuran, methyltetrahydrofuran, 2-hexanone anisole, cresol, 4- propylanisole, 2-phenylethanol, 4-methylacetophenone, 4-propylphenol, 4- ethylguaiacol, 2,6-dimethoxyphenol, 4-methyl-2,6-dimethoxyphenol, 4-propyl- 2,6-dimethoxy phenol and the like.

It goes without saying that the chemical nature of the heterogenates comprised in the at least one liquid pyrolysis oil fraction, as detailed above, are different from the typical heterogenates as comprised in conventional crude oil and/or fractions thereof and Fischer-Tropsch oils.

In Step 3 of the method of the present invention, at least a portion of the heterogenates contained in the at least one liquid pyrolysis oil fraction, as detailed above, can then be further removed by subjecting said at least one liquid pyrolysis oil fraction to a liquid extraction process and/or a liquid-solid adsorption process and/or a precipitation process to produce at least one purified pyrolysis oil fraction.

Within the context of the present invention, the expression “at least one purified pyrolysis oil fraction” is intended to denote one or more than one purified pyrolysis oil fraction and which is substantially free of heterogenates, in particular substantially free of oxygenates and nitrogenates.

Within the context of the present invention, the term “substantially free of heterogenates” is intended to denote less than 5000 parts per million (ppm), in particular less than 2000 ppm, more in particular less than 1000 ppm is present in the at least one purified pyrolysis oil fraction, said concentration being expressed as weight percentage of the sum of the heteroatoms present in the heterogenates present in the at least one purified pyrolysis oil fraction.

Within the context of the present invention, the term “substantially free of oxygenates and nitrogenates” is intended to denote less than 3000 parts per million (ppm), in particular less than 1500 ppm, more in particular less than 750 ppm, and even more in particular less than 300 ppm, is present in the at least one purified pyrolysis oil fraction, said concentration being expressed as weight percentage of the sum of the oxygen atoms and the nitrogen atoms present in the oxygenates and nitrogenates, respectively, present in the at least one purified pyrolysis oil fraction.

In certain embodiments of the method of the present invention, the one or more liquid pyrolysis oil fractions, as detailed above, are further subjected to a fractional distillation prior to be subjected to a liquid extraction process and/or a liquid-solid adsorption process and/or a precipitation process in Step 3 of the method of the present invention.

This being said, this means that the one or more liquid pyrolysis oil fractions, as detailed above, can be obtained through a fractional condensation of the gaseous pyrolysis product, as detailed above, or, through a combination of a partial and/or fractional condensation of the gaseous pyrolysis product, as detailed above, followed by a fractional distillation.

In general, fractional distillation is a fractionating and separation technique known to the skilled in the art where cuts are made on boiling point ranges. Preferably, the fractional distillation of the one or more liquid pyrolysis oil fractions, as detailed above, is carried out in a distillation column or distillation tower. Herein, the terms distillation column and distillation tower are used interchangeably.

As used herein, distillation columns are made up of several components, each of which is used either to transfer heat energy or enhance material transfer. The distillation column consists of several major parts such as a (1) vertical shell where separation of the one or more fractions is carried out, (2) column internals, such as trays or plates, or packings, that are used to enhance fraction separation, (3) a reboiler to provide the necessary vaporization for the fractional distillation, (4) a condenser to cool and condense the gaseous products leaving the top of the distillation column, and (5) a reflux drum to hold the condensed gaseous products from the top of the distillation column so that liquid can be recycled back to said column.

In general, the distillation column for use in the method of the present invention can be a tray or a plate distillation column, or a packed distillation column. Preferably, the distillation column is a tray or a plate distillation column.

Advantageously, the one or more liquid pyrolysis oil fractions, as detailed above, are fed near the middle of a tray distillation column to a feed tray. This feed tray divides the distillation column into a top section, i.e. a rectifying section, and a bottom section, i.e. a stripping section. The rectifying section refers to the trays between the feed tray and the top of the distillation column. In the rectifying section the aim is to concentrate a lighter fraction of said pyrolysis oil fraction (i.e. a first sub-fraction) in the vapor phase. The stripping section refers to the trays between the bottom of the distillation column and the feed tray. In the stripping section the aim is to concentrate a heavier fraction of said pyrolysis oil fraction in the liquid phase (i.e. second sub-fraction). The feed flows down the distillation column where it is collected at the bottom of the reboiler. Heat is supplied to the reboiler to generate vapour. The source of heat can be any suitable medium. Preferably, the source of heat is pressurized steam. The vapour raised in the reboiler is reintroduced into the unit at the bottom of the distillation column.

Furthermore, the distillation column for use in the method of the present invention can be operated in batch mode or in continuous mode. According to the method of the present invention, the fractional distillation of the one or more liquid pyrolysis oil fractions, as obtained by the at least partial condensation of the gaseous pyrolysis product, as detailed above, may comprise one fractional distillation over one distillation column or, alternatively, multiple fractional distillations in series over multiple distillations columns. By interception of the one or more distillation columns at certain heights, distillate fractions with a required boiling point can be tapped off at different positions on the one or more distillation columns.

The inventors have now surprisingly found that when the one or more liquid pyrolysis oil fractions, as detailed above, are purified by subjecting said one or more liquid pyrolysis oil fraction to a liquid extraction process and/or a liquid-solid adsorption process and/or a precipitation process in Step 3 of the method according to the present invention, at least one purified pyrolysis oil fraction can now be successfully recovered. Moreover, said at least one purified pyrolysis oil fraction is characterized by a markedly improved stability to filming and gelling upon standing and to tar induced problems in distillations and other treatments. Furthermore, said at least one purified pyrolysis oil fraction demonstrates a decreased tendency to fouling. The latter is convincingly evidenced by an improved clarity of said at least one purified pyrolysis oil fraction when compared to the liquid pyrolysis oil fraction as obtained from Step 2. Furthermore, the at least one purified pyrolysis oil fraction contains high amounts of unsaturated compounds having double bonds, in particular terminal double bonds (i.e. terminal alkenes), thereby enabling further valorization of said at least one purified pyrolysis oil fraction, for instance via the use of functionalization chemistry. According to one embodiment of the method of the present invention, in Step 3, at least one liquid pyrolysis oil fraction, as detailed above, is purified by removing at least a portion of the heterogenates contained therein by a liquid extraction process thereby producing at least one purified pyrolysis oil fraction [purified fraction (E), herein after].

In general, liquid extraction processes are known to the skilled person in the art of process chemistry and purification techniques applied therein. In general, a liquid extraction process is a process that uses substantially immiscible solvents to partition components, as present in the material to be extracted, based on their relative solubility and affinity. It is understood that the term liquid extraction processes refers to the contacting of the at least one liquid pyrolysis oil fraction, as detailed above, with an extracting agent, said extracting agent being a liquid extracting agent. At least two phases are formed after the addition of the liquid extracting agent due to the differences in compatibility with each other, i.e. due to the differences in density said phases can separate by gravity. The liquid extracting agent is chosen in such a way that at least a portion, in particular substantially all heterogenates as comprised in the at least one liquid pyrolysis oil fraction have a higher affinity towards the added liquid extracting agent. Therefore, at least a partial mass transfer of the heterogenates from the at least one liquid pyrolysis oil fraction to the liquid extracting agent may occur.

In general, the liquid extraction process can be carried out in a liquid-liquid extraction column, which can be (1) an agitated liquid-liquid extraction column such as a pulsed column or a rotating disc contactor (RDC) column, or (2) a static liquid-liquid extraction column such as a sieve tray column or a packed column.

In Step 3 of the method of the present invention, the at least one liquid pyrolysis oil fraction, as detailed above, can be fed to the liquid-liquid extraction column at, or near, the bottom thereof. The liquid extraction process may be performed in batch mode or in continuous mode.

In Step 3 of the method of the present invention, before feeding the at least one liquid pyrolysis oil fraction to the liquid-liquid extraction column, as detailed above, and depending on the chemical nature in terms of the molecular weight (i.e. the boiling point) of said at least one liquid pyrolysis oil fraction, as detailed above, said at least one liquid pyrolysis oil fraction may be first diluted with an apolar organic solvent to lower the viscosity of said at least one liquid pyrolysis oil fraction. Any apolar organic solvent or mixture thereof can be used to lower the viscosity thereof. Furthermore, it is understood that the apolar organic solvent or mixture thereof is easy to be removed by evaporation without altering the molecular weight distribution of the recovered pyrolysis oil fraction. Non-limiting examples of suitable apolar organic solvents notably include n-pentane, n-hexane, cyclohexane, n-heptane, and mixtures thereof.

As to the amount of the apolar organic solvent, it is understood that the skilled person in the art will practise said apolar organic solvent in a suitable amount according to standard and general practice known by said skilled person in the art.

According to certain embodiments of the method of the present invention, prior to the liquid extraction process of Step 3, the weight ratio the apolar organic solvent, as detailed above, to the at least one liquid pyrolysis oil fraction, as detailed above, is equal to or at least 1 to 5, or equal to or at least 1 to 2, or equal to or at least 1 to 1 , or equal to or at least 2 to 1 , or equal to or at least 5 to 1.

According to certain embodiments in Step 3 of the method of the present invention, the liquid extraction process is carried out at a temperature from 10 °C to 50 °C, preferably from 10 °C to 40 °C, more preferably from 10 °C to 30 °C.

According to certain embodiments in Step 3 of the method of the present invention, the liquid extraction process is carried out at a pressure equal to or less than 5.0 bara, preferably equal to or less than 3.0 bara, more preferably equal to ambient pressure.

In Step 3 of the method of the present invention, the liquid extracting agent advantageously comprises equal to or more than 50 wt. % of at least one polar organic solvent, preferably equal to or more than 70 wt. %, preferably equal to or more than 85 wt. %, preferably equal to or more than 90 wt. %, preferably equal to or more than 95 wt. %, relative to the total weight of the liquid extracting agent.

If desired, depending on the chemical nature in terms of the molecular weight (i.e. the boiling point) of the at least one liquid pyrolysis oil fraction, as detailed above, the liquid extracting agent may consist essentially of at least one polar organic solvent.

For the purpose of the present invention, the expression “consists essentially of” is intended to denote that any additional component different from the at least one polar organic solvent is present in minor amounts in the liquid extracting agent, being understood that these latter do not substantially modify the properties, in particular the liquid extracting properties, of said liquid extracting agent. In particular, within the context of the present invention, the term “consist essentially of” is intended to denote that the liquid extracting agent comprises less than 3.0 wt. % of other components than the at least one polar organic solvent, preferably less than 2.0 wt. %, more preferably less than 1.0 wt. %, most preferably less than 0.5 wt. %, relative to the total weight of the liquid extracting agent.

In general, the at least one polar organic solvent can be any polar organic solvent that has low miscibility with the at least one liquid pyrolysis oil fraction.

Within the context of the present invention, the expression “at least one polar organic solvent” is intended to denote one or more than one polar organic solvent. Mixtures of polar organic solvents can also be used for the purpose of the present invention. ln the rest of the text, the expression “polar organic solvent” is understood, for the purposes of the present invention, both in the plural and the singular form, that is to say that the liquid extracting agent of the present invention may comprise one or more than one polar organic solvent. It goes without saying that the expression such as “equal to or more than 50 wt. % of at least one polar organic solvent” refers either to the amount of polar organic solvent when the liquid extracting agent comprises only one polar organic solvent, or to the sum of the amounts of polar organic solvent when the liquid extracting agent comprises more than one polar organic solvent. This being said, it means that it is necessary that, when more than one polar organic solvent is present, then it is the sum of the amounts of each polar organic solvent that must be equal to or more than 50 wt. %, relative to the total weight of the liquid extracting agent.

Non-limiting examples of suitable polar organic solvents as used in Step 3 of the method of the present invention notably include tri-ethanolamine, triethylene glycol, acetonitrile, hydroxyacetone (acetol), methanol, ethanol, isopropanol, and mixtures of two or more thereof. Preferably, the polar organic solvent is selected from methanol, ethanol, isopropanol, or mixtures of two or more thereof. According to certain embodiments in Step 3 of the method of the present invention, if desired, the liquid extracting agent further comprises water, in addition to the presence of the at least one polar organic solvent, as detailed above.

According to certain embodiments in Step 3 of the method of the present invention, the liquid extracting agent further comprises water in an amount equal to or less than 50 wt. % of water, preferably equal to or less than 30 wt. %, preferably equal to or less than 15 wt. %, preferably equal to or less than 10 wt. %, preferably equal to or more less 5 wt. %, relative to the total weight of the liquid extracting agent. The inventors have found that for certain fractions of the at least one liquid pyrolysis oil fraction, as detailed above, in particular when the at least one liquid pyrolysis oil fraction is liquid at room temperature, the liquid extracting agent can be tuned with water in order to increase the yield of the purified fraction (E) while maintaining a good purification of the at least one liquid pyrolysis oil fraction into said recovered purified fraction (E) whereby significant amounts of heterogenates can be successfully removed, as demonstrated in the working examples.

According to certain embodiments in Step 3 of the method of the present invention, the weight ratio of the liquid extracting agent, as detailed above, to the at least one liquid pyrolysis oil fraction, as detailed above, can be from 10:1 to 1:10, preferably from 5:1 to 1:5, preferably from 2:1 to 1:2, more preferably from 1.3:1 to 1:1.5.

In general, the liquid extracting agent may be added on top of the liquid-liquid extraction column. When the liquid extracting agent is a mixture comprising a polar organic solvent and water, the polar organic solvent and water may be added separately or directly as a premixed mixture to the liquid- liquid extraction column.

It is furthermore understood that in Step 3 of the method of the present invention, after the liquid extraction process, the purified fraction (E) may be repeatedly resubjected to the liquid extraction process in order to increase the extraction efficiency in terms of the efficient removal of heterogenates.

Alternatively, according to another embodiment of the method of the present invention, in Step 3, at least one liquid pyrolysis oil fraction, as detailed above, is purified by removing at least a portion of the heterogenates contained therein by a liquid-solid adsorption process thereby producing at least one purified pyrolysis oil fraction [purified fraction (A), herein after].

In general, liquid-solid adsorption processes are known to the skilled person in the art of process chemistry and purification techniques applied therein. As used herein, the term adsorption encompasses the use of at least one solid support, i.e. at least one adsorbent, to remove heterogenates from the at least one liquid pyrolysis oil fraction, as detailed above. The adsorption may occur by “physisorption” in which the adsorption involves surface attractions, or by “chemisorption” where there are actual chemical changes in the heterogenates that are being removed.

In Step 3 of the method of the present invention, the liquid-solid adsorption process is carried out by contacting the at least one liquid pyrolysis oil fraction, as detailed above, with at least one adsorbent.

In Step 3 of the method of the present invention, before carrying out the liquid-solid adsorption process, the at least one liquid pyrolysis oil fraction, as detailed above, may be first diluted with an apolar organic solvent to lower the viscosity thereof. Any apolar organic solvent can be used to lower the viscosity of the at least one liquid pyrolysis oil fraction, as detailed above. Furthermore, it is understood that the apolar organic solvent or mixture thereof is easy to be removed by evaporation without altering the molecular weight distribution of the recovered pyrolysis oil fraction. Non-limiting examples of suitable apolar organic solvents notably include n-pentane, n-hexane, cyclohexane, n-heptane, and mixtures thereof. Preferably, the apolar organic solvent is n-hexane.

As to the amount of the apolar organic solvent, it is understood that the skilled person in the art will practise said apolar organic solvent in a suitable amount according to standard and general practice known by said skilled person in the art.

According to certain embodiments of the method of the present invention, prior to the liquid-solid adsorption process of Step 3, the weight ratio the apolar organic solvent, as detailed above, to the at least one liquid pyrolysis oil fraction, as detailed above, is equal to or at least 1 to 5, or equal to or at least 1 to 2, or equal to or at least 1 to 1 , or equal to or at least 2 to 1 , or equal to or at least 5 to 1. ln Step 3 of the method of the present invention, the at least one adsorbent may be any porous material or fine material, both characterized by a large active surface, known to have an application as an adsorbent. Non-limiting examples of suitable adsorbents notably include (1) activated carbon, (2) clays such as bentonite which may be activated, (3) molecular sieves such as faujasites (13X, CaX, NaY, CaY, and ZnX), chabazites, clinoptilolites, and LTA (4A, 5A) zeolites, and metal organic frameworks (MOFs), (4) oxides such as silica, silica gel including functionalized silica gel such as amino-functionalized silica gel, alumina such as promoted alumina or activated alumina, and mixtures of two or more thereof, as well as other porous materials that can be used to remove or separate heterogenates.

According to a preferred embodiment in Step 3 of the method of the present invention, the at least one adsorbent is chosen among silica, silica gel, bentonite, or mixtures of two or more thereof.

According to certain embodiments in Step 3 of the method of the present invention, the liquid-solid adsorption process is carried out at a temperature from 10 °C to 100 °C, preferably from 20 °C to 50 °C.

According to certain embodiments in Step 3 of the method of the present invention, the liquid-solid adsorption process is carried out at a pressure from 0.0 bara to 15.0 bara, preferably from 0.0 bara to 4.0 bara, preferably from 0.0 bara to 1.0 bara, more preferably from 0.0 bara to 0.1 bara, most preferably from 0.0 bara to 0.01 bara.

According to certain embodiments in Step 3 of the method of the present invention, the weight ratio of the at least one adsorbent, as detailed above, to the at least one liquid pyrolysis oil fraction, as detailed above, is from 1:1 to 1:20, preferably from 1:2 to 1:10, more preferably from 1:3 to 1:5.

In Step 3 of the method of the present invention, the at least one adsorbent, after carrying out the liquid-solid adsorption process, may be regenerated according to standard and general practice known by the skilled person in the art. Non-limiting examples of such adsorbent regeneration processes notably include temperature swing adsorption (TSA) and displacement. Temperature swing adsorption refers to an adsorbent regeneration process whereby the regeneration of the adsorbent is achieved by an increase in temperature such as by sending a heated gas through a fixed bed of adsorbent to remove or desorb most of the contaminants. The adsorbent is then often cooled before resumption of the liquid-solid adsorption process. Displacement refers to an adsorbent regeneration process whereby the regeneration of the adsorbent is achieved by desorbing the contaminant with another solvent that takes its place on the adsorbent. Non-limiting examples of such solvents notably include carbon disulphide, alcohols such as methanol, ethanol, isopropanol, aromatic solvents, acetone, ethyl acetate, and mixtures thereof. Preferably, when the adsorbent is regenerated via displacement, the solvent is methanol, said methanol which can then afterwards be removed and reused.

According to another embodiment of the method of the present invention, in Step 3, the purified fraction (E), as detailed above, is further subjected to a liquid-solid adsorption process, as detailed above, thereby producing at least one purified pyrolysis oil fraction [purified fraction (EA), herein after].

The inventors have surprisingly found that when the liquid extracting agent is a mixture comprising equal to or more than 50 wt. % of methanol in the presence of water, relative to the total weight of the liquid extracting agent, and the resulting purified fraction (E) is then submitted to a liquid-solid adsorption process with silica gel as the adsorbent, a purified fraction (EA) is recovered from the at least one liquid pyrolysis oil fraction, as detailed above, whereby a further portion of heterogenates can be successfully removed, while simultaneously leading to a good yield of the purified fraction (EA).

According to another embodiment of the method of the present invention, in Step 3, the purified fraction (A), as detailed above, is further subjected to a liquid extraction process, as detailed above, thereby producing at least one purified pyrolysis oil fraction [purified fraction (AE), herein after].

It is further understood that all definitions and preferences as described above equally apply for this embodiment and all further embodiments, as described below.

According to a preferred embodiment of the method of the present invention, in Step 3, the at least one liquid pyrolysis oil fraction, as detailed above, is liquid at room temperature and is first contacted with a liquid extracting agent thereby producing a purified fraction (E), wherein said liquid extracting agent comprises equal to or more than 50 wt. % of at least one polar organic solvent, as detailed above, preferably equal to or more than 70 wt. %, preferably equal to or more than 85 wt. %, preferably equal to or more than 90 wt. %, preferably equal to or more than 95 wt. %, and wherein said liquid extracting agent further comprises water in an amount equal to or less than 50 wt. %, preferably equal to or less than 30 wt. %, preferably equal to or less than 15 wt. %, preferably equal to or less than 10 wt. %, preferably equal to or more less 5 wt. %, relative to the total weight of the liquid extracting agent. The at least one polar organic solvent is preferably selected from the group consisting of methanol, ethanol, isopropanol, and mixtures of two or more thereof.

The inventors have found that when the at least one liquid pyrolysis oil fraction, as detailed above, is (semi-)solid at room temperature, it is preferable that in the liquid extraction process, the liquid extracting agent consists essentially of the at least one polar organic solvent, as detailed above, preferably wherein the at least one polar organic solvent is chosen among methanol, ethanol, isopropanol, and mixtures of two or more thereof, more preferably isopropanol, and that the liquid pyrolysis oil fraction is first diluted with an apolar organic solvent, as detailed above. Instead of diluting the liquid pyrolysis oil fraction, said fraction can alternatively be heated to a temperature from 30 °C to 90 °C, preferably from 50 °C to 75 °C, in order to soften said fraction and decreasing the viscosity of said fraction to values preferably equal to or lower than 200 mPa.s. It has to be mentioned that also a combination of dilution with an apolar solvent, as detailed above, and heating can be applied in order to realize said preferred viscosity being equal to or lower than 200 mPa.s.

Alternatively, in Step 3 of the method of the present invention, the at least one liquid pyrolysis oil fraction being (semi-)solid at room temperature can be subjected to a precipitation process wherein the at least one liquid pyrolysis oil fraction is contacted with an appropriate precipitating agent, thereby producing at least one purified pyrolysis oil fraction [purified fraction (P), herein after].

The precipitation process can be carried out according to standard and general practice known by a person skilled in the art. In general, the temperature at which the precipitation process is performed will depend on the solubility of the at least one liquid pyrolysis oil fraction being (semi-)solid at room temperature in the precipitating agent, and moreover on the chemical nature in terms of the molecular weight (i.e. the boiling point) of said fraction. The temperature should be selected in such a way that part of the at least one liquid pyrolysis oil fraction being (semi-)solid is dissolved in the precipitating agent. With part it is understood that at least 10 % is dissolved but that the solubility is lower than 50 %. In case of a low solubility, the at least one liquid pyrolysis oil fraction being (semi-)solid at room temperature can be first heated to a temperature whereby said fraction experiences a (substantial) solubility in the precipitating agent, followed by a subsequent cooling of said mixture to induce the precipitation process. Preferably, the precipitating agent is tuned in such a way that the precipitation process can be realized in a temperature range from 90 °C to 0 °C, more preferably from 50 °C to 10 °C, even more preferably at ambient conditions.

Preferably, the precipitating agent can be chosen among ethyl acetate, isopropanol, methyl ethyl ketone, tetrahydrofuran, or mixtures thereof.

Other advantages and particularities of the present invention will become apparent from the following description of some particular embodiments of the method according to the present invention. This description is only given by way of example and is not intended to limit the scope of the invention. The reference numerals used in the description relate to the annexed drawings wherein:

Figure 1. is a schematic flow diagram illustrating an embodiment of Step 1 and Step 2 of the method according to the present invention; and

Figure 2. and Figure 3. are schematic flow diagrams illustrating embodiments of Step 3 of the method according to the present invention.

The invention generally relates to a method for producing one purified pyrolysis oil fraction from a hydrocarbon based waste plastic, whereby said hydrocarbon based waste plastic comprises polyolefins and heteroatom- based contaminants, in particular polyethylene terephthalate (PET).

Unless otherwise mentioned or indicated, the boiling points of the various pyrolysis oil fractions are to be understood as the boiling points at atmospheric pressure.

A particular embodiment of Step 1 and Step 2 of the method according to the invention is illustrated in Figure 1. In particular the different pipes, reactors, distillation columns, and other components are indicated schematically in this diagram but the necessary valves and pumps have not been indicated and described in detail as a skilled person knows how and where to provide such pumps and valves.

In a first phase of the process as illustrated in Figure 1, the hydrocarbon based waste plastic comprising polyolefins and heteroatom-based contaminants is stored and sorted in different silos 1. Via a hopper 2 and a conveyor belt 3 the hydrocarbon based waste plastic is fed into an extruder 4 wherein said hydrocarbon based waste plastic is molten. The solid hydrocarbon based waste plastic is fed into an inlet 5 of the extruder 4 and leaves the extruder 4 through its outlet 6. When moving from the inlet 5 to the outlet 6 the hydrocarbon based waste plastic is gradually heated to a temperature of for example 350 °C so that said hydrocarbon based waste plastic is in a molten state at the outlet 6. During the heating, any moisture will evaporate and halogenated polymers, such as PVC and the like, are dehydrohalogenated. Moreover, VOC’s (volatile organic compounds) may be formed in the extruder 4. All of these gases/vapours are removed from the extruder 4 via an evacuation pipe 7 to a scrubber 8. In the scrubber 8, the VOC’s are separated from the moisture containing for example hydrochloric acid, which is collected via pipe 9 whilst the VOC’s are fed into an incinerator device 10 to recover the energy contained in those gases. The incinerator device 10 preferably comprises a combined heat and power generator.

The molten hydrocarbon based waste plastic produced in the extruder 4 is supplied via a pipe 11 to a pyrolysis reactor 12. This pyrolysis reactor 12 contains a liquid phase 13 which is pyrolyzed. The liquid phase 13 is preferably stirred by means of a stirring device 14 to achieve a uniform temperature in the liquid phase 13. Also any solid particles as comprised in the molten hydrocarbon based waste plastic, in particular non-pyrolyzable solids such as inorganic substances, are kept in suspension by means of the stirring device 14. The stirring device 14 preferably comprises a scraper which scrapes along the inner wall of the pyrolysis reactor 12 to scrape off any char that may be formed on the inner wall of the pyrolysis reactor 12.

The temperatures indicated in the present specification are the average temperature, more particularly the average temperature of the whole liquid phase 13. When the liquid phase 13 is sufficiently stirred so that it has a substantially uniform temperature, the temperature can be measured on one location in the liquid phase 13, in particular at a distance from the wall of the pyrolysis reactor 12.

The temperature for pyrolyzing can be selected to maximize the yield of condensable saturated and unsaturated hydrocarbons, in particular alkanes/alkenes in the gaseous pyrolysis product, i.e. to minimize the production of a fraction comprising non-condensable gases, such as for instance one or more Ci to Cs gases, and further to minimize the production of char as well. The temperature for pyrolysis of the liquid phase 13 is maintained at a predetermined temperature from 300 °C to 650 °C, or from 400 °C to 600 °C, or from 450 °C to 550 °C. The temperature is selected to achieve a pyrolysis of the polyolefins comprised in the molten hydrocarbon based waste plastic.

In addition to the hydrocarbon based waste plastic one or more additives may be fed into the pyrolysis reactor 12. Such additives may comprise one or more catalysts such as metal oxide and metal carbonate catalysts. Some of these additives may also function as acid scavengers for capturing hydrochloric acid as a by-product.

The gas pressure in the pyrolysis reactor 12 is selected so that part of the pyrolysis products can evaporate from the liquid phase 13 and produce a gaseous phase forming a gaseous pyrolysis product 15 above the liquid phase 13 in the pyrolysis reactor 12. The gas pressure in the pyrolysis reaction 12 is from 0.1 bara to 10.0 bara, or from 0.3 bara to 5.0 bara, or from 0.5 bara to 2.0 bara.

The gaseous pyrolysis product 15 is continuously removed from the pyrolysis reactor 12 via a pipe 16. The gaseous pyrolysis product 15 is fed via the pipe 16 to a quencher 17. In the quencher 17 the gaseous pyrolysis product 15 is partially condensed at 30 °C and is separated in a non condensable gas fraction, such as for instance a fraction comprising one or more Ci to Cs gases, and in a first liquid pyrolysis oil fraction comprising a C6 to C40 fraction or even higher alkanes/alkenes. At the top of the quencher 17, the non-condensable gases are removed via a pipe 18 to the storage tank of the incinerator device 10. The liquid pyrolysis oil fraction is fed via a pipe 19 to a buffer tank 20.

From the buffer tank 20 this first liquid pyrolysis oil fraction is fed via a pipe 21 to a first distillation column 22, which is provided with a condenser 23 and a reboiler 24. Preferably, prior to feeding the first liquid pyrolysis oil fraction to the first distillation column 22, a major part of the tar fraction is first removed. Said tar fraction contains a predetermined amount of high boiling materials having for example a boiling point higher than 500 °C, or higher than 525 °C, or higher than 550 °C. These high boiling materials can either be formed during the pyrolysis of the hydrocarbon based waste plastic thereby producing the gaseous pyrolysis product 15, and/or in the gaseous pyrolysis product 15 itself, and/or during at least partially condensing said gaseous pyrolysis product 15 thereby producing the liquid pyrolysis oil fraction, and/or in the resulting liquid pyrolysis oil fraction itself upon standing in function of time, for instance in the buffer tank 20. These high boiling materials can comprise tar products, (additive) polymerization products, filming and gelling material, and heterogenates. Suitable processes for removing the tar fraction from the first liquid pyrolysis oil fraction, as detailed above, notably include filtration, or bottom flash distillation in order to separate a single gaseous phase from the tar fraction for instance at a temperature higher than 500 °C when expressed at atmospheric pressure or at a lower corresponding temperature when applying underpressure, or by using a thin film evaporator, optionally by applying underpressure. Preferably, the tar fraction is removed from the first liquid pyrolysis oil fraction by using a thin film evaporator applying underpressure.

The first distillation column 22 is operated under a partial vacuum of 60 mbara to enable a more efficient separation of the first liquid pyrolysis oil fraction into two sub-fractions of said first liquid pyrolysis oil fraction. At the top, a first sub-fraction containing hydrocarbons having a boiling point of for example lower than 400 °C, and containing thus mainly the lighter C6 to C25 hydrocarbons, is removed from the first distillation column 22 and is at least partly fed via a pipe 25 to a reservoir 26.

The range of carbon chain lengths contained in this first sub fraction of the first liquid pyrolysis oil fraction can be modified, in particular the final boiling point thereof, based on the desired specifications of this first sub fraction. The bottom fraction of the first liquid pyrolysis oil fraction (i.e. a second sub-fraction), which is removed at the bottom of the first distillation column 22, contains higher hydrocarbons having a boiling point higher than 400 °C. This bottom fraction is fed via a pipe 27 to a second distillation column 28 which is provided with a condenser 29 and a reboiler 30.

At the bottom of the second distillation column 28 a heavier first fraction of the second sub-fraction of the first liquid pyrolysis oil fraction is removed with a too high boiling point which is fed via a pipe 31 to a reservoir 32. This heavier first fraction of the second sub-fraction of the first liquid pyrolysis oil fraction comprises for example hydrocarbons having a boiling point higher than 500 °C. A lighter second fraction of the second sub-fraction of the first liquid pyrolysis oil fraction containing hydrocarbons having a boiling point of from example from 400 to 450 °C, and containing thus mainly C26 to C30 hydrocarbons, is removed from near the top of the second distillation column 28 and is fed via a pipe 33 to a reservoir 34. Furthermore, a third fraction of the second sub-fraction of the first liquid pyrolysis oil fraction containing hydrocarbons having a boiling point of from example from 450 to 500 °C, and containing thus mainly C31 to C36 hydrocarbons, is removed from near the middle of the second distillation column 28 and is fed via a pipe 35 to a reservoir 36.

It is clear that the operation of the first distillation column 22 and the second distillation column 28 can be adjusted as a function of the desired composition, i.e. the carbon chain length or the boiling point range, of the various fractions of the first liquid pyrolysis oil fraction. In other words, the first liquid pyrolysis oil fraction can be fractionated in more sub-fractions, as detailed above. The pyrolysis reactor 12 is preferably a continuous stirred-tank pyrolysis reactor. In this reactor, the polyolefins comprised in the molten hydrocarbon based waste plastic are continuously pyrolyzed. Feeding of the molten hydrocarbon based waste plastic is, on average, in equilibrium with the production of the gaseous pyrolysis product 15. In other words, there will always be an amount of liquid phase 13 present in the pyrolysis reactor 12 although the amount/level thereof may vary to some extent.

Next, with reference to a liquid extraction process 37 according to Step 3 of the method of the present invention, the first sub-fraction of said first liquid pyrolysis oil fraction present in the reservoir 26 is fed from the reservoir 26 via a pipe 38 to a liquid-liquid extraction column 39, preferably at, or near, the bottom of said liquid-liquid extraction column 39, in order to remove a first portion of the heterogenates contained in said first sub-fraction. This particular embodiment according to Step 3 of the method of the present invention is illustrated in Figure 2.

The liquid extracting agent for the liquid-liquid extraction column 39 is a mixture of 50 wt. % of methanol and 50 wt. % of water, relative to the total weight of the liquid extracting agent. The liquid extracting agent to feed ratio in the liquid-liquid extraction column 39 can be low, for instance less than 1.5.

The liquid extracting agent is added to the liquid-liquid extraction column 39 via a pipe 40. After liquid extraction, a purified fraction (E) exits the top of the liquid-liquid extraction column 39 via a pipe 41. The purified fraction (E) comprises less than 750 ppm of heterogenates.

An extract 42 is drawn from the bottom of the liquid-liquid extraction column 39 and is fed via a pipe 43 to a solvent recovery column 44. A top product 45 from the solvent recovery column 44 comprises more than 90 wt. % of methanol and a low amount of heterogenates, depending on the liquid extracting agent to feed ratio in the liquid-liquid extraction column 39. A bottom product 46 from the solvent recovery column 44 comprises mainly water, and is enriched in heterogenates. The bottom product 46 can be further purified, for instance by decanting processes known in the art, and the water comprised therein can be further recycled.

The top product 45 is fed to a mixing unit 47 wherein it can be further mixed with a methanol stream 48 and a water stream 49 in order to give the liquid extracting agent for the liquid-liquid extraction column 39 via the pipe 40.

The presence of water in the liquid-liquid extraction column 39 improves the recovery of the purified fraction (E) whereby significant amounts of heterogenates can (still) be successfully removed, while simultaneously leading to a good yield of said purified fraction (E). It was further found that the purified fraction (E) is stable upon standing without any fouling, and whereby said purified fraction (E) maintains high amounts of unsaturated compounds having double bonds, in particular terminal double bonds (i.e. terminal alkenes). The presence of such unsaturated compounds as comprised in the purified fraction (E) enables further valorization of said purified fraction (E) into valuable chemicals via the use of functionalization chemistry.

Alternatively, with reference to the liquid extraction process 37 according to Step 3 of the method of the present invention, the lighter second fraction of the second sub-fraction of the first liquid pyrolysis oil fraction as present in the reservoir 34 is fed from the reservoir 34 via the pipe 38 to the liquid-liquid extraction column 39, preferably at, or near, the bottom of said liquid-liquid extraction column 39, in order to remove a first portion of the heterogenates contained therein. This particular embodiment of the present invention is illustrated in Figure 2. The above descriptions for purifying the first sub-fraction of said first liquid pyrolysis oil fraction via the liquid extraction process of Figure 2 apply mutatis mutandis to the lighter second fraction of the second sub-fraction of the first liquid pyrolysis oil fraction as present in the reservoir 34.

With reference to a liquid-solid adsorption process 50 according to Step 3 of the method of the present invention, the third fraction of the second sub-fraction of the first liquid pyrolysis oil, as present in the reservoir 36 is fed from the reservoir 36 via a pipe 51 to a mixing unit 52 wherein said third fraction is mixed and diluted with n-hexane in order to lower its viscosity upon further purification. n-Flexane is fed to the mixing unit 52 via a pipe 53. After dilution, this third fraction is mixed with an adsorbent, preferably silica gel or bentonite, in a mixing unit 54 in order to remove a first portion of the heterogenates contained in said third fraction. The adsorbent is added to the mixing unit 54 via a pipe 55. This particular embodiment according to Step 3 of the method of the present invention is illustrated in Figure 3.

The weight ratio of the adsorbent to this third fraction, as detailed above, is from 1:1 to 1:20, preferably from 1:2 to 1:10, more preferably from 1:3 to 1:5.

After mixing, the mixture exits the mixing unit 54 and is fed to a filtration unit 56, wherein a purified fraction (A), diluted in n-hexane, is separated from the adsorbent with adsorbed heterogenates. The adsorbent with adsorbed heterogenates leaving the filtration unit 56 is fed to a displacement unit 57 in order to regenerate the adsorbent.

Next, the purified fraction (A) is mixed with a second part of the adsorbent in a mixing unit 59 in order to remove a second portion of the heterogenates contained in said purified fraction (A). The adsorbent is added to the mixing unit 59 via a pipe 58. After mixing, the mixture exits the mixing unit 59 and is fed to a filtration unit 60, wherein the purified fraction (A), still diluted in n-hexane, is separated from the adsorbent with adsorbed heterogenates. The adsorbent with adsorbed heterogenates leaving the filtration unit 60 is fed to the mixing unit 54 via the pipe 55.

Further, the purified fraction (A) is mixed with a third part of the adsorbent in a mixing unit 61 in order to remove a third portion of the heterogenates contained in said purified fraction (A). The adsorbent is added to the mixing unit 61 via a pipe 62. After mixing, the mixture exits the mixing unit 61 and is fed to a filtration unit 63, wherein the purified fraction (A), still diluted in n-hexane, is separated from the adsorbent with adsorbed heterogenates. The adsorbent with adsorbed heterogenates leaving the filtration unit 63 is fed to the mixing unit 59 via the pipe 58. The purified fraction (A) is then transferred via a pipe 64 to a solvent recovery column 65. The purified fraction (A) is drawn from the bottom of the solvent recovery column 65 via a pipe 66. The purified fraction (A) comprises less than 300 ppm of heterogenates. n-Hexane is recuperated as the top product from the solvent recovery column 65. The recuperated n-hexane can then be reused and fed to the mixing unit 52 via the pipe 53.

In order to regenerate the adsorbent used in the liquid-solid adsorption process 50 above, as said, the adsorbent with adsorbed heterogenates, leaving the filtration unit 56, is fed to the displacement unit 57 in order to regenerate the adsorbent. Especially, the adsorbent is fed via a pipe 67 to a mixing unit 68 where the adsorbent is mixed with a solvent, preferably methanol. Upon mixing, the heterogenates are at least partially desorbed (i.e. displaced) from the adsorbent and readily solubilized in the solvent.

After mixing, the mixture exits the mixing unit 68 and is fed to a filtration unit 69, wherein the adsorbent is separated from the solvent with the solubilized heterogenates. Then, the separated adsorbent leaving the filtration unit 69 is fed to a mixing unit 71 via a pipe 70 wherein the adsorbent is subsequently mixed with another part of the solvent. Upon mixing, the heterogenates are now further desorbed from the adsorbent and readily solubilized in the other part of the solvent. After mixing, the mixture exits the mixing unit 71 and is fed to a filtration unit 72, wherein the adsorbent is separated from the other part of the solvent with the solubilized heterogenates. Then, the separated adsorbent leaving the filtration unit 72 is fed to a mixing unit 74 via a pipe 73. The other part of the solvent leaving the filtration unit 72 is fed to the mixing unit 68. In the mixing unit 74, the separated adsorbent is mixed with yet another part of the solvent. Upon mixing, the heterogenates are now even further desorbed from the adsorbent and readily solubilized in the yet another part of the solvent. After mixing, the mixture exits the mixing unit 74 and is fed to a filtration unit 75, wherein the adsorbent is separated from the yet another part of the solvent with the solubilized heterogenates. Then, the separated adsorbent leaving the filtration unit 75 is fed to the mixing unit 61 via the pipe 62. The yet another part of the solvent leaving the filtration unit 75 is fed to the mixing unit 71.

The solvent with the solubilized heterogenates leaving the filtration unit 69 is fed to a solvent recovery column 77 via a pipe 76. The heterogenates are drawn from the bottom of the solvent recovery column 77 via a pipe 78, while the solvent is recuperated as the top product from the solvent recovery column 77. The solvent can then be reused and fed to the mixing unit 74 via a pipe 79. Alternatively, with reference to a liquid-solid adsorption process 50 according to Step 3 of the method of the present invention, the purified fraction (E), as obtained by subjecting the lighter second fraction of the second sub fraction of the first liquid pyrolysis oil fraction as present in the reservoir 34, as detailed above, to the liquid extraction process, as detailed above, is fed via the pipe 51 to the mixing unit 52 wherein said purified fraction (E) is mixed and diluted with n-hexane in order to lower its viscosity upon further purification. After dilution, this purified fraction (E) is mixed with an adsorbent, preferably silica gel or bentonite, in a mixing unit 54 in order to remove a further portion of the heterogenates contained in said purified fraction (E). The above descriptions for purifying the third fraction of the second sub-fraction of the first liquid pyrolysis oil, as present in the reservoir 36 via the liquid-solid adsorption process of Figure 3 apply mutatis mutandis to this purified fraction (E).

When this purified fraction (E), after being extracted in particular with a liquid extracting agent being a mixture of 50 wt. % of methanol and 50 wt. % of water, relative to the total weight of the liquid extracting agent, is further subjected to the liquid-solid adsorption process of Figure 3, wherein the adsorbent is silica gel, a purified fraction (EA) is recovered whereby a further portion of heterogenates can be successfully removed, while simultaneously leading to a good yield of the purified fraction (EA). Figure 4. is a schematic elution profile as used in the determination of the polar content in a (crude) pyrolysis oil fraction and purified pyrolysis oil fractions thereof (see test methods).

Figure 5. is a GC-MS analysis of a “medium polar” fraction of a polyal pyrolysis oil fraction distilled between 200 °C - 370 °C, said “medium polar” fraction as obtained after separation by flash chromatography of said polyal pyrolysis oil fraction distilled between 200 °C - 370 °C, the chromatographic separation being done over a silica gel column using the elution profile as described in Table 4.

Figure 6. is a GC-MS analysis of a “high polar” fraction of a polyal pyrolysis oil fraction distilled between 200 °C - 370 °C, said “high polar” fraction as obtained after separation by flash chromatography of said polyal pyrolysis oil fraction distilled between 200 °C - 370 °C, the chromatographic separation being done over a silica gel column using the elution profile as described in Table 4.

Figure 7. is a flash chromatogram with UV-VIS response, using the elution profile as described in Table 4, illustrating the polar content of a polyal pyrolysis oil fraction distilled between 180 °C - 270 °C before and after a liquid-solid adsorption process using silica gel as the adsorbent.

Figure 8. is a flash chromatogram with UV-VIS response, using the elution profile as described in Table 4, illustrating the polar content of a polyal pyrolysis oil fraction distilled between 425 °C - 500 °C before and after a precipitation process using isopropanol as the precipitating agent.

Figure 9. is a flash chromatogram with UV-VIS response, using the elution profile as described in Table 4, illustrating the polar content of a 180 °C - 350 °C fraction, said fraction originating from a mixed plastic film-based crude pyrolysis oil, before and after a liquid-solid adsorption process using silica gel as the adsorbent.

Figure 10. is a flash chromatogram with UV-VIS response, using the elution profile as described in Table 4, illustrating the polar content of a 180 °C - 350 °C fraction, said fraction originating from a mixed plastic film-based crude pyrolysis oil, before and after a liquid-solid adsorption process using bentonite as the adsorbent.

EXAMPLES

The invention will be now described in more details with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the invention.

Test methods

Initial and final boiling point:

ASTM D2887 is limited to fractions having a boiling point of 538 °C or lower at atmospheric pressure, and therefore was extended to 575 °C.

Olefin content:

The olefin content was determined using PIONA analysis according to ASTM D8071.

Atomic O content:

Atomic oxygen content was determined using a micro-pyrolysis unit followed by elemental analysis according to ASTM D5291. The atomic O content was then determined according to the difference between 100% and the summarized atomic contents for C, H, and atomic N. It is to be noted that for this test method any halogen atoms present are included in the atomic O content.

Atomic N content:

Atomic nitrogen content was determined using sample combustion followed by ultraviolet fluorescence detection according to ASTM D5762. Long term stability:

A 200 g sample of a liquid pyrolysis oil fraction was placed in a stoppered glass flask, said glass flask having a diameter of 5 cm. The temperature was then raised to 150 °C and the sample was shaken vigorously for 2 minutes. Afterwards, the sample was allowed to cool to room temperature, or to a temperature circa 5 °C above the softening point in case the sample originated from a wax fraction, and stored without agitation. After two weeks, the respective stoppered glass flask was observed for any deposition and filming. In particular, deposition/filming was decided to be present when a clear deposit/film was observed respectively on the bottom and on the side walls of the respective stoppered glass flask.

Acid value:

The acid value of the liquid pyrolysis oil fractions was measured according to the standard ASTM D664-04.

Tar/gel/film forming content, expressed as a tar-value:

A specific tar test was designed to quantify any quality improvement upon removal of tar/gel/film forming compounds from pyrolysis oil fractions. Moreover, 10 - 11 g (± 14 mL) samples were prepared and conditioned at a temperature just above the melting point. In case melting did not occur at 60 °C, said samples were diluted with xylene (1:5 w/w). After equilibration, the respective samples were centrifuged at 4500 rpm for 3 minutes. The liquid was subsequently removed by decantation and wiping of the walls of the tube. The mass of the semi-wet deposited gel-like material was determined and the tar fraction was expressed in wt. % for each of said corresponding pyrolysis oil fractions, relative to the total weight of each of said corresponding pyrolysis oil fractions. Polar content:

A specific test using column flash chromatography was designed in order to monitor the removal of polar contaminants from the pyrolysis oil fractions, including high molecular weight (i.e. high boiling) heterogenates, in particular oxygenates and nitrogenates, since the use of the classical petrochemical test methods (atomic oxygen content and/or LOWOX according to the standard ASTM D7423 as for the low molecular weight oxygen comprising molecule content) did not allow to obtain reproducible results as a consequence of the completely different nature of the crude pyrolysis oil originating from a hydrocarbon based waste plastic in comparison to classical crude oils in terms of the nature of the various contaminants comprised therein and/or the amounts of said contaminants.

In particular, the various heterogenates including oxygenates, nitrogenates, and/or halogenates were separated by flash chromatography over a silica gel column, i.e. a silica gel stationary phase (Buchi Flashpure cartridges). Elution is performed by a three solvent system (n-hexane, tetrahydrofuran, and methanol) whereby the polarity of the solvent, i.e. the mobile phase, is gradually increased from n-hexane via tetrahydrofuran to methanol. Moreover, about 1.3 g sample was analyzed by eluting said sample over two silica gel flash columns which were connected in series. Two flash pure silica columns of Buchi were used, each with a capacity of 24 ml_ (12 grams), particle size 35 - 45 A, pore size 53 - 80 A and specific area 500 - 600 m ² /g. An elution profile was set with a gradually increasing polarity (n-hexane tetrahydrofuran (BHT stabilized) anhydrous methanol). The flow rate was set at 30 mL/min. The elution profile is illustrated in Figure 4 and in Table 4 of the present invention. Specifically, the heterogenates were detected simultaneously by UV-VIS spectroscopy, in particular by a UV-VIS scanning detector (254 - 400 nm).

In general, five different chromatographic fractions were distinguished in the chromatograms depending on the respective polarities of the heterogenates contained therein. Molecular entities with a retention time lower than 3 minutes were considered apolar, i.e. non-polar (saturated and unsaturated hydrocarbons and aromatic hydrocarbons). At retention times equal to or higher than 3 minutes, polar entities appeared, their respective polarities thereby increasing with increasing retention times. Reference is hereby made to Figures 7 - 10, as observed in the flash chromatographic analysis, said Figures 7 - 10 thereby illustrating the five different chromatographic fractions depending on the respective polarities of the heterogenates contained therein, ranging from apolar to most polar.

Hydrocarbon based waste plastic

Two different types of hydrocarbon based waste plastics comprising polyolefins and heteroatom-based contaminants were used, i.e. (1) polyal material and (2) mixed plastic film material.

The (1) polyal material constitutes a waste stream which was obtained during a treatment of beverage cartons, said beverage cartons originating from a sorting process of mixed post-consumer waste plastic material. These beverage cartons are typically made up of organic fibers originating from e.g. cardboard and LDPE film materials, whereby these beverage cartons further comprise laminated polymeric layers, barrier polymers, and aluminium metal. The polyal material as such constitutes the residue which is left after removing the paperboard/cardboard component from the beverage cartons (i.e. typically 75 wt. %, relative to the total weight of the beverage carton). The polyal material as used herein mainly comprises low-density polyethylene (LDPE) as polyolefin, aluminium metal, and heteroatom -based polymers such as polyethylene terephthalate (PET), polyamide 6 (PA6), and polyvinylidene chloride (PVDC). Additionally, since the sorting process of the beverage cartons is not entirely faultless, a small amount of non-beverage packaging related contaminations such as polyurethane (PU), polystyrene (PS), polyvinylchloride (PVC), acrylonitrile butadiene styrene (ABS), and other organic residues, may be present in the polyal material as used herein. The various and specific components of the typical polyal material are further summarized in Table 1 below.

All contents in Table 1 are given in wt. %, relative to the total weight of the polyal material, unless stated otherwise.

Table 1: Typical polyal material as the hydrocarbon based waste plastic

* including PS, PU, ABS, PVC, and biomass The (2) mixed plastic film material constitutes a waste stream which was obtained as a result from a mechanical sorting of waste plastics in a film/foil polymeric fraction, a hard 3D material comprising polymer fraction, biomass residues and a non-polymeric fraction comprising mainly metals and inorganic materials. The mixed plastic film material is rich in polyolefins. However, a specific treatment using general methods known in the art such as shredding/cutting, washing and sinking/floating, is necessary in order to further increase the level of polyolefins as comprised within the mixed plastic film material. Since this treatment is not entirely faultless, a small amount of contaminations such as PET, PVC, PS, and other organic residues may be present in the mixed plastic film material as used herein. The various and specific components of the typical mixed plastic film material are further summarized in Table 2 below. All contents in Table 2 are given in wt. %, relative to the total weight of the mixed plastic film material, unless stated otherwise.

Table 2: Typical mixed plastic film material as the hydrocarbon based waste plastic

* including PU, ABS, PVC, biomass, and inorganic materials.

Pyrolysis oil fractions

A specific sample of both the polyal material and the mixed plastic film material, as described above, were obtained from a plastic waste provider and were separately pyrolyzed using distinct pyrolysis reactors at elevated temperatures for a certain period of time in an essentially oxygen free atmosphere, thereby causing cleavage of the chemical bonds in both the polyal material and the mixed plastic film material. Consequently, the molecular weight of the polymers as comprised within said materials was reduced to a level whereby said materials could be evacuated from the pyrolysis reactor so that a gaseous pyrolysis product was produced for each of said polyal and mixed plastic film materials. Then, each of said gaseous pyrolysis product was partially condensed in order to give liquid to waxy pyrolysis oil fractions. The state of matter of said pyrolysis oil fractions was highly dependent of the chemical nature of the hydrocarbon based waste plastic which was fed to the pyrolysis reactor, the pyrolysis conditions, and the condensation conditions for condensing the gaseous pyrolysis products. ln particular, the polyal sample was first molten and continuously fed in said molten state to a stirred pyrolysis reactor, operated at atmospheric pressure, wherein said material was pyrolyzed at 450 °C under inert conditions. The gaseous pyrolysis products were continuously removed from the pyrolysis reactor and partially condensed. The gaseous pyrolysis products contained 15 wt. % of non-condensable products and 85 wt. % of condensable products. The condensable products were then decanted in order to remove any entrained water, thereby resulting in a final pyrolysis oil fraction, i.e. a crude polyal pyrolysis oil. This crude polyal pyrolysis oil was then further processed according to the methods of the present invention. The chemical nature of the crude polyal pyrolysis oil is further specified in Table 3 below.

In particular, the mixed plastic film sample was pyrolyzed in a similar way as in case of the polyal material as described in the paragraph above. The resulting mixed plastic film-based crude pyrolysis oil was then further processed according to the methods of the present invention. The chemical nature of the mixed plastic film-based crude pyrolysis oil is further specified in Table 3 below.

Table 3: Crude polyal pyrolysis oil and mixed plastic film-based crude pyrolysis oil

The specifications of Table 3 indicate that, given the olefin contents of both the crude pyrolysis oils, further valorization of these unsaturated moieties as contained within said crude pyrolysis oils is hereby enabled, for instance via the use of functionalization chemistry into valuable chemical building blocks. However, the specifications of Table 3 also indicate that this valorization potential of the crude pyrolysis oils is impeded by the long- term instability of these crude pyrolysis oils via the activation of the unsaturated bonds contained therein, the presence of low boiling and high boiling heterogenates and tar/gel/film forming materials leading to fouling, and whereby these crude pyrolysis oils are further characterized by a dark colour and an irritating smell. Example 1:

The crude polyal pyrolysis oil was first distilled at atmospheric pressure, thereby removing a distillate polyal pyrolysis oil fraction having a boiling point between 200 °C and 370 °C, i.e. corresponding to a Cn - C23 carbon range. As said, before distillation, the crude polyal pyrolysis oil was largely unstable. Upon standing, gelling/filming and fouling occurred, i.e. dark coloured and tacky particles of tar products, filming and gelling material, and heterogenates were deposited on the surfaces of vessels and/or distillation columns upon further processing of the crude polyal pyrolysis oil.

With regards to the liquid distillate polyal fraction 200 °C - 370 °C the fouling was largely reduced. However, upon standing, this liquid distillate polyal fraction 200 °C - 370 °C still demonstrated some degree of fouling. Furthermore, this liquid distillate polyal fraction 200 °C - 370 °C was still containing too high amounts of heterogenates, in particular heterogenates containing oxygen-containing acidic functionalities, and therefore a further purification was envisaged. As described above, heterogenates could induce adverse properties as instability through various side reactions, hydrophilicity, and the poisoning of catalytic systems used in subsequent chemical reactions upon valorization of this liquid distillate polyal fraction 200 °C - 370 °C.

The liquid distillate polyal fraction 200 °C - 370 °C was subjected to a liquid-solid adsorption process using silica gel as the adsorbent. Moreover, 8.0 g of this particular distillate fraction was admixed with varying amounts, i.e. 0.25 g, 0.50 g, and 1.00 g, of silica gel powder (silica gel 60 Macherey-Nagel, particle size 63 - 200 pm). Optionally, this distillate fraction may first be diluted with an apolar organic solvent, such as n-hexane, to lower the viscosity thereof. The mixture was mixed for 5 minutes at room temperature. Afterwards, the mixture was centrifuged, decanted, and optionally the apolar organic solvent was removed.

It was observed that the distillate polyal pyrolysis oil fraction 200 C - 370 °C demonstrated a decreased tendency to fouling after the above- described liquid-solid adsorption process using silica gel as the adsorbent. Moreover, the clarity of said distillate polyal pyrolysis oil fraction markedly improved with increasing amounts of the silica gel powder as the adsorbent in the liquid-solid adsorption process. In order to demonstrate the complex and atypical chemical nature of the crude polyal pyrolysis oil, a 8.15 g sample of the liquid distillate polyal fraction 200 °C - 370 °C was separated by flash chromatography over a silica gel column, i.e. a silica gel stationary phase (Buchi Flashpure cartridges) using a elution profile as described in Table 4. Moreover, 8.15 g sample was analyzed by eluting said sample over two silica gel flash columns which were connected in series. Two flash pure silica columns of Buchi were used, each with a capacity of 24 mL (12 grams), particle size 35 - 45 A, pore size 53 - 80 A and specific area 500 - 600 m ² /g. The flow rate was set at 30 mL/min. Specifically, the heterogenates were detected simultaneously by UV-VIS spectroscopy, in particular by a UV-VIS scanning detector (254 - 400 nm).

Table 4: Elution profile flash chromatography of distillate polyal pyrolysis oil fraction 200 °C - 370 °C, starting from the crude polyal pyrolysis oil

Three fractions were respectively collected, each fraction being characterized by a particular retention time depending on the polarity of the heterogenates as contained within said fraction. The first fraction was considered non-polar (i.e. saturated and unsaturated hydrocarbons and aromatic hydrocarbons). However, the second fraction and third fraction, whereby the polarity of said third fraction was higher when compared to the polarity of said second fraction, were further analyzed via gas chromatography- mass spectrometry (GC-MS) upon the presence of the various heterogenates as contained therein.

Figure 5 shows the GC-MS analysis of the second fraction. 11 heteroatom -based contaminants were identified and characterized in terms of their molecular weights, as further described in Table 5 below.

Table 5

Figure 6 shows the GC-MS analysis of the third fraction. Three heteroatom -based contaminants were identified and characterized in terms of their molecular weights, as further described in Table 6 below. Table 6

Example 2:

The crude polyal pyrolysis oil was first distilled at atmospheric pressure, thereby removing a distillate polyal pyrolysis oil fraction having a boiling point between 200 °C and 370 °C. As said, before distillation, the crude polyal pyrolysis oil was largely unstable. Upon standing, gelling/filming and fouling occurred, i.e. dark coloured and tacky particles of tar products, filming and gelling material, and heterogenates were deposited on the surfaces of vessels and/or distillation columns upon further processing of the crude polyal pyrolysis oil.

With regards to the liquid distillate polyal fraction 200 °C - 370 °C the fouling was largely reduced. However, upon standing, this liquid distillate polyal fraction 200 °C - 370 °C still demonstrated some degree of fouling. Furthermore, this liquid distillate polyal fraction 200 °C - 370 °C was still containing too high amounts of heterogenates, in particular heterogenates containing oxygen-containing acidic functionalities, and therefore a further purification was envisaged. As described above, heterogenates could induce adverse properties as instability through various side reactions, hydrophilicity, and the poisoning of catalytic systems used in subsequent chemical reactions upon valorization of this liquid distillate polyal fraction 200 °C - 370 °C.

The liquid distillate polyal fraction 200 °C - 370 °C was subjected to a liquid-solid adsorption process using silica gel as the adsorbent. Moreover, 5 g of this particular distillate fraction was admixed with 15 g of n-hexane and 5 g of silica gel powder (silica gel 60 Macherey-Nagel, particle size 63 - 200 pm). As already stated above, a distillate fraction might optionally first be diluted with an apolar organic solvent, such as n-hexane, to lower the viscosity thereof. The mixture was mixed for 5 minutes at room temperature. Afterwards, the mixture was centrifuged, decanted, and the apolar organic solvent, i.e. n-hexane, was removed.

In order to assess the removal of a portion of the heterogenates contained in the liquid distillate polyal fraction 200 °C - 370 °C, in particular heterogenates containing oxygen-containing acidic functionalities, thereby leading to an improved purity of said polyal fraction, the acid value was measured before and after purification as a first robust and reliable indicative test method.

The acid value of the liquid distillate polyal fraction 200 °C - 370 °C after liquid-solid adsorption process using silica gel as the adsorbent was equal to 0.0, while the acid value of the liquid distillate polyal fraction 200 °C - 370 °C before liquid-solid adsorption process using silica gel as the adsorbent was equal to 11.5. This clearly indicates that the liquid-solid adsorption process is very efficient in removing the acidic heterogenates.

Alternatively, the liquid distillate polyal fraction 200 °C - 370 °C was subjected to a liquid extraction process using methanol and/or water as the liquid extracting agent. Moreover, the liquid distillate polyal fraction 200 °C - 370 °C was extracted three times with the liquid extracting agent, whereby the weight ratio of the liquid extracting agent to the liquid distillate polyal fraction 200 °C - 370 °C was equal to 1:1. The results were summarized in Table 7 below. Table 7: Liquid extraction process of the liquid distillate polyal fraction 200 °C - 370 °C; acid values

* The acid value of the crude liquid distillate polyal fraction 200 °C - 370 °C was equal to 11.5. ** The acid value of the liquid distillate polyal fraction 200 °C - 370 °C after liquid-solid adsorption process using silica gel as the adsorbent was equal to 0.0.

*** Acid values of the liquid distillate polyal fraction 200 °C - 370 °C after a 3 ^rd extraction. It is to be noted that this 3 ^rd extraction was performed with 20 wt. % H2O in methanol.

The results in Table 7 show that a liquid extraction process is effective in purifying a liquid pyrolysis oil fraction, i.e. the liquid distillate polyal fraction 200 °C - 370 °C, by removing a significant portion of the heterogenates contained therein. The results in Table 7 further demonstrate that good results are obtained with the liquid extracting agent comprising equal to or more than 50 wt. % of methanol as the polar organic solvent in the presence of water. In case the liquid distillate polyal fraction 200 °C - 370 °C is purified via the use of a liquid extracting agent comprising more than 50 wt. % of water, or a liquid extracting agent consisting essentially of water, a significantly lower portion of the heterogenates is effectively removed. Example 3:

The same crude polyal pyrolysis oil of Example 2 was first distilled at atmospheric pressure, thereby removing and fractionating the low boiling compounds having a boiling point equal to or lower than 350 °C. Here, the lower limit temperature was set at 180 °C instead of the lower limit temperature of 200 °C as in case of Example 2. The resulting bottom fraction from this first distillation was further distilled in a still put under vacuum in order to obtain a high boiling fraction and a final bottom residue, whereby a cutoff was made at 500 °C (equivalent atmospheric boiling point). Less dark-coloured distillates were obtained, while said distillates demonstrated a markedly higher stability towards sedimentation, gelling and film formation.

The various distillate pyrolysis oil fractions, starting from the crude polyal pyrolysis oil, are described and listed in Table 8 below.

Table 8: Distillate polyal pyrolysis oil fractions, starting from the crude polyal pyrolysis oil The results in Table 8 show that quality improvements are realized for the various distillate polyal pyrolysis oil fractions in terms of contaminants and tar-values. First of all, these fractions were less coloured. Secondly, these various fractions were observed to be more stable in the long-term, and said fractions were more easily processed in any further steps. However, the various distillate polyal pyrolysis oil fractions were still containing too high amounts of heterogenates, in particular heterogenates containing inter alia oxygen- containing acidic functionalities, and therefore a further purification was envisaged. As described above, heterogenates could induce adverse properties as instability through various side reactions, hydrophilicity, and the poisoning of catalytic systems used in subsequent chemical reactions upon valorization of these distillate polyal pyrolysis oil fractions.

In order to remove at least a portion of the heterogenates contained in these distillate polyal pyrolysis oil fractions, said fractions were subjected to further purification steps without altering the olefin content (i.e. the double bonds) contained therein.

Whereas in Example 2, a 200 °C - 370 °C fraction was treated, now a different fraction, being the liquid distillate polyal fraction 180 °C - 270 °C, as described in Table 8, was treated. Said fraction was subjected to a liquid- solid adsorption process using silica gel as the adsorbent. Moreover, 40 g of this particular distillate fraction was admixed with 10 g of silica gel powder (silica gel 60 Macherey-Nagel, particle size 63 - 200 pm). Optionally, this distillate fraction may first be diluted with an apolar organic solvent, such as n-hexane, to lower the viscosity thereof. The mixture was mixed for 5 minutes at room temperature. Afterwards, the mixture was centrifuged, decanted, and the apolar organic solvent was removed, and a slight pale liquid was obtained.

Figure 7 shows the polar content of the distillate polyal pyrolysis oil fraction 180 °C - 270 °C as illustrated in the flash chromatogram with UV-VIS response, using the elution profile as described in Table 4, before and after the above-described liquid-solid adsorption process using silica gel as the adsorbent. Based on the information as disclosed in this Figure 7, it was evidenced that a significant portion of the heterogenates as originally contained in the distillate polyal pyrolysis oil fraction 180 °C - 270 °C was now effectively removed via the liquid-solid adsorption process. At the same time, the silica gel adsorbent adsorbed the colouring material and the materials causing the irritating smell which were initially present in the distillate polyal pyrolysis oil fraction 180 °C -270 °C.

The resulting purified polyal pyrolysis oil fraction 180 °C - 270 °C is suitable to be subjected to further valorization steps, either by further fractionation/separation and/or by chemical functionalization. Furthermore, the resulting purified polyal pyrolysis oil fraction can also serve as a suitable raw material towards other petrochemical processes, such as naphtha cracking, thereby demonstrating a significantly reduced risk of catalyst poisoning.

Example 4:

The wax distillate polyal fraction 425 °C - 500 °C, as described in Table 8, was subjected to a precipitation process using isopropanol as the precipitating agent. Moreover, 800 g of isopropanol was added to 200 g of the distillate polyal fraction 425 °C - 500 °C. The mixture was admixed at room temperature for 4 hours. The resulting dispersion was then filtered through a coarse paper filter thereby applying a moderate underpressure. After precipitation and filtration, the purified polyal pyrolysis oil fraction 425 °C - 500 °C was then rinsed with 400 g of isopropanol. The rinsed material was further dried in an oven at 70 °C under vacuum (< 10 mbar). The overall recovery of purified polyal pyrolysis oil fraction 425 °C - 500 °C was equal to 45 wt. %. The dark colour and irritating smell were largely removed.

Figure 8 shows the polar content of the distillate polyal pyrolysis oil fraction 425 °C - 500 °C as illustrated in the flash chromatogram with UV-VIS response, using the elution profile as described in Table 4, before and after the above-described precipitation process using isopropanol as the precipitating agent. Based on the information as disclosed in this Figure 8, it was evidenced that a significant portion of the heterogenates as originally contained in the distillate polyal pyrolysis oil fraction 425 °C - 500 °C was now effectively removed via the precipitation process. At the same time, coloured impurities were effectively removed in order to give an almost white/crystalline material having no irritating smell.

The resulting purified polyal pyrolysis oil fraction 425 °C - 500 °C is suitable to be subjected to further valorization steps, either by further fractionation/separation and/or by chemical functionalization. Furthermore, the resulting purified polyal pyrolysis oil fraction can also serve as lubricant and/or wax in industrial applications.

Example 5:

Whereas Examples 1 to 4 describe processes applied to a polyal based crude pyrolysis oil, the following examples describe processes applied to a mixed plastic film-based crude pyrolysis oil. The mixed plastic film-based crude pyrolysis oil was first filtered in order to remove a major part of the tar/gel/film forming material which was present in said mixed plastic film-based crude pyrolysis oil. In particular, a silica gel bed filtration was performed in order to remove a major part of the tar/gel/film forming material by using a composite filter, whereby said composite filter was made by putting 0.5 g of silica gel (silica gel 60 Macherey-Nagel, particle size 63 - 200 pm) between two paper filters (Ederol nr. 15, 0 5.5 cm) on top of a glass frit of a Millipore® vacuum filtration system. A moderate underpressure was applied to enhance filtration. Before starting the filtration process, the mixed plastic film-based crude pyrolysis oil and the filtration equipment were preheated at 80 °C. After filtration, 89 wt. % of the mixed plastic film-based crude pyrolysis oil was recovered. In particular, Table 9 describes the respective tar-values of the mixed plastic film-based crude pyrolysis oil before and after the filtration process. Table 9: Tar-values of the mixed plastic film-based crude pyrolysis oil, before and after silica gel bed filtration

The results in Table 9 show that as a consequence of the performed filtration process the tar-value of the respective mixed plastic film- based crude pyrolysis oil decreased from 1.3 wt. % to 0.2 wt. %. After filtration, a clearly less dark filtrate was obtained which demonstrated an improved stability towards sedimentation, gelling, and film formation. However, the crude pyrolysis oil was still characterized by a too high tar-value and furthermore containing too high amounts of heterogenates.

Therefore, after the filtration process, the mixed plastic film-based crude pyrolysis oil was split in two fractions, on the one hand a fraction having a boiling point lower than 350 °C with a lower limit of 180 °C (i.e. 180 °C - 350 °C fraction) and on the other hand a fraction having a boiling point higher than 350 °C.

The fraction having a boiling point between 180 °C - 350 °C was subjected to a liquid-solid adsorption process using silica gel as the adsorbent. Moreover, 40 g of this 180 °C - 350 °C fraction was admixed with 10 g of silica gel powder (silica gel 60 Macherey-Nagel, particle size 63 - 200 pm). Optionally, this fraction may be first diluted with an apolar organic solvent, such as n-hexane, to lower the viscosity thereof. The mixture was mixed for 5 minutes at room temperature. Afterwards, the mixture was centrifuged, decanted, and optionally the apolar organic solvent was removed and a colour change was observed initially starting from dark orange to red to light yellow- green while changing the smell to a typical naphtha smell. The overall recovery of the purified 180 °C - 350 °C fraction was equal to 68 wt. %. Figure 9 shows the polar content of this 180 °C - 350 °C fraction, originating from mixed plastic film-based crude pyrolysis oil, as illustrated in the flash chromatogram with UV-VIS response, using the elution profile as described in Table 4, before and after the above-described liquid-solid adsorption process using silica gel as the adsorbent. Based on the information as disclosed in this Figure 9, it was evidenced that a significant portion of the heterogenates as originally contained in this 180 °C - 350 °C fraction was effectively removed via the liquid-solid adsorption process. At the same time, the silica gel adsorbent adsorbed the colouring material and the materials causing the irritating smell which were initially present in this 180 °C - 350 °C fraction.

Alternatively, the 180 °C - 350 °C fraction was subjected to a liquid-solid adsorption process using bentonite as the adsorbent. Moreover, 40 g of this fraction was admixed with 10 g of bentonite (neutral bentonite originating from a vegetable oil refinery). Optionally, this fraction may be first diluted with an apolar organic solvent, such as n-hexane, to lower the viscosity thereof. The mixture was mixed for 5 minutes at room temperature. Afterwards, the mixture was centrifuged, decanted, and optionally the apolar organic solvent was removed. The overall recovery of the purified 180 °C - 350 °C fraction was equal to 80 wt. %.

Figure 10 shows the polar content of this 180 °C - 350 °C fraction, originating from mixed plastic film-based crude pyrolysis oil, as illustrated in the flash chromatogram with UV-VIS response, using the elution profile as described in Table 4, before and after the above-described liquid-solid adsorption process using bentonite as the adsorbent. Based on the information as disclosed in this Figure 10, it was evidenced that a portion of the heterogenates as originally contained in this 180 °C - 350 °C fraction was effectively removed via the liquid-solid adsorption process. At the same time, the bentonite adsorbent adsorbed colouring material and material causing the irritating smell which were initially present in this 180 °C - 350 °C fraction, thereby reducing in this way said irritating smell.