Method for producing a hydrocarbon product from mixed polymer waste

Abstract

The present invention relates to a method for producing a hydrocarbon product from mixed polymer waste, preferably plastic waste and / or post consumer plastic waste, wherein said mixed polymer waste comprises 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, based on the total weight of the mixed polymer waste, comprising: (i) feeding said mixed polymer waste into an extruder; (ii) adding chemicals, preferably alkali metal salt and / or alkali earth metal salt, to said mixed polymer waste to degrade said compounds, preferably polymer, comprising heteroatoms; (iii) removing degradation products derived from said compounds, preferably polymer, comprising heteroatoms from said hydrocarbon product; and (iv) pyrolysing the hydrocarbon product in a fluidised bed reactor to obtain pyrolysis product.

Description

[0001] Method

[0002] INTRODUCTION

[0003] The present invention relates to a method for producing a pyrolysis product from mixed polymer waste comprising 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, including polymers, comprising heteroatoms, as well as to a system for producing a pyrolysis product from such mixed polymer waste. The present invention also relates to a method and system for recycling mixed polymer waste comprising a pre-treatment to remove compounds, including polymers, comprising heteroatoms, followed by pyrolysis in a fluidised bed reactor. The mixed polymer waste used as feedstock in the present invention is, e.g. plastic waste and / or post consumer plastic waste (PCW).

[0004] BACKGROUND

[0005] Polyethylene and polypropylene constitute almost 50% of the overall plastics production in the European Union, and of this 40% is used for packaging. European waste directives state that by 2040, the recycled content of packaging will need to be 50- 65%, depending on the packaging type. However, there are no recycling solutions commercially available for multi-layer flexible packaging film, which inherently comprises a variety of different polymer types.

[0006] Chemical recycling transforms polymer waste back to virgin materials. For example, pure polyethylene and polypropylene can be recycled by pyrolysis. The recycling process produces a range of different hydrocarbon products, e.g. waxes, hydrocarbon oils, naphtha, and other light gases. Some of these products are suitable for entry into the refinery and / or petrochemical value chain to ultimately become ethylene or propylene for production of further polyethylene or polypropylene respectively.

[0007] Multilayer flexible film used for food packaging, a common type of post consumer plastic waste, is much more challenging to recycle than monomaterial polyethylene or polypropylene because it contains a mixture of different polymers including heteroatomcontaining polymers such as polyethylene terephthalate (PET) and polyamide (PA). Polymers like PET and PA cause significant problems during pyrolysis due to the formation of hazardous or corrosive degradation products, which decrease the product quality and damage equipment in the recycling plant. This problem is exacerbated with multilayer flexible films because they also tend to comprise heteroatom-containing additives, e.g. plasticisers, dyes, UV or light stabilisers etc. Like PET and PA, these additives tend to form problematic degradation products during pyrolysis. Moreover, given the huge variety of different additives used in multilayer flexible film packaging it is difficult to predict, and control, the degradation reactions and degradation products that will be produced. This problem is only likely to grow in the future as more and more plastic waste is mechanically recycled, and new combinations of additives accumulate in the recycled materials.

[0008] As a result, the majority of commercial plastic recycling plants only accept postconsumer plastic waste (PCW) which contains low levels of PET and PA. For PA, this is often as low as <1 wt%, and for PET it is typically < 2 wt%. These requirements mean that multi-layer flexible packaging film usually cannot be recycled in such plants or it can only be accepted after mechanical sorting, which takes considerable time and energy, and achieves only modest levels of separation.

[0009] The prior art in the area of plastic recycling has focussed on handling PVC, rather than heteroatom-containing polymers. US5608136, for example, discloses a method for thermal pyrolysis of waste plastic to produce high quality fuel oil, wherein a pre-treatment step is optionally carried out in an extruder. US5608136 recognises that in the conditions of the extruder, which are typically 200 to 400 °C, elimination of HCI from PVC occurs, and needs to be handled. It is suggested that this can be done by introducing an alkaline agent to react with the HCI.

[0010] Similarly, US2023 / 0159834 discloses systems and methods for pyrolysis of plastic waste, wherein the focus is on the removal of chlorine. In US2023 / 0159834 plastic waste is introduced into a pyrolysis environment, such as a fluidised bed, with a melt extruder. The resulting pyrolysis effluent may undergo further processing, including a second thermal cracking step. US2023 / 0159834 discloses that hydrochloric acid that is produced in the process as a result of the presence of polyvinyl chloride or polyvinylidene chloride in the plastic feedstock can be removed using guard beds prior to the second thermal cracking step and / or by adding calcium oxide to the heat transfer particles in the fluidised bed reactor

[0011] SUMMARY OF INVENTION

[0012] Viewed from a first aspect, the present invention provides a method for producing a pyrolysis product from mixed polymer waste, preferably plastic waste and / or post consumer plastic waste, wherein said mixed polymer waste comprises 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, based on the total weight of the mixed polymer waste, comprising: (i) feeding said mixed polymer waste into an extruder; (ii) adding chemicals, preferably alkali metal salt and / or alkali earth metal salt, to said mixed polymer waste to degrade said compounds, preferably polymer, comprising heteroatoms;

[0013] (iii) removing degradation products derived from said compounds, preferably polymer, comprising heteroatoms from said hydrocarbon product; and

[0014] (iv) pyrolysing the hydrocarbon product in a fluidised bed reactor to obtain pyrolysis product.

[0015] Viewed from a further aspect the present invention provides a system for producing a pyrolysis product from mixed polymer waste, preferably according to a method as hereinbefore described, comprising: an extruder for conversion of mixed polymer waste comprising 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, and chemicals, preferably alkali metal salt and / or alkali earth metal salt, into a mixture of hydrocarbon product and degradation products derived from the compounds, preferably polymer, comprising heteroatoms; optionally a melt filter for receiving the mixture of hydrocarbon product and degradation products from the extruder and removing solid degradation products from said hydrocarbon product; a degassing unit for receiving the hydrocarbon product from the extruder, or if present melt filter, and removing volatile degradation products from said hydrocarbon product; and a fluidised bed pyrolysis unit for receiving the hydrocarbon product from the extruder, or if present degassing unit, and pyrolysing said hydrocarbon product to obtain a pyrolysis product.

[0016] Viewed from a further aspect the present invention provides a system for producing a pyrolysis product from mixed polymer waste, comprising: an extruder for conversion of mixed polymer waste comprising 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, and chemicals, preferably alkali metal salt and / or alkali earth metal salt, into a mixture of hydrocarbon product and degradation products derived from the compounds, preferably polymer, comprising heteroatoms, wherein said extruder has a barrel comprising a devolatilization outlet for removing volatile degradation products; optionally a melt filter for receiving the mixture of hydrocarbon product and degradation products from the extruder and removing solid degradation products from said hydrocarbon product; and a fluidised bed pyrolysis unit for receiving the hydrocarbon product from the extruder, or if present degassing unit, and pyrolysing said hydrocarbon product to obtain a pyrolysis product.

[0017] Viewed from a further aspect the present invention provides a method for recycling mixed polymer waste comprising:

[0018] (i) feeding said mixed polymer waste into an extruder, preferably a single screw extruder;

[0019] (ii) adding chemicals, preferably alkali metal salt and / or alkali earth metal salt, to said mixed polymer waste to degrade said compounds, preferably polymer, comprising heteroatoms;

[0020] (iii) removing degradation products derived from said compounds, preferably polymer, comprising heteroatoms from said hydrocarbon product; and

[0021] (iv) pyrolysing the hydrocarbon product in a fluidised bed reactor to obtain pyrolysis product.

[0022] Viewed from a further aspect the present invention provides a system for recycling mixed polymer waste, comprising: an extruder for conversion of mixed polymer waste comprising 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, and chemicals, preferably alkali metal salt and / or alkali earth metal salt, into a mixture of hydrocarbon product and degradation products derived from the compounds, preferably polymer, comprising heteroatoms; optionally a melt filter for receiving the mixture of hydrocarbon product and degradation products from the extruder and removing solid degradation products from said hydrocarbon product; a degassing unit for receiving the hydrocarbon product from the extruder, or if present melt filter, and removing volatile degradation products from said hydrocarbon product; and a fluidised bed pyrolysis unit for receiving the hydrocarbon product from the extruder, or if present degassing unit, and pyrolysing said hydrocarbon product to obtain a pyrolysis product.

[0023] Viewed from a further aspect the present invention provides a system for recycling mixed polymer waste, comprises: an extruder for conversion of mixed polymer waste comprising 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, and chemicals, preferably alkali metal salt and / or alkali earth metal salt, into a mixture of hydrocarbon product and degradation products derived from the compounds, preferably polymer, comprising heteroatoms, wherein said extruder has a barrel comprising a devolatilization outlet for removing volatile degradation products; optionally a melt filter for receiving the mixture of hydrocarbon product and degradation products from the extruder and removing solid degradation products from said hydrocarbon product; and a fluidised bed pyrolysis unit for receiving the hydrocarbon product from the extruder, or if present degassing unit, and pyrolysing said hydrocarbon product to obtain a pyrolysis product.

[0024] DEFINITIONS

[0025] As used herein the term “hydrocarbon product” refers to a blend or mixture of hydrocarbons. The hydrocarbons solely comprise C and H atoms.

[0026] As used herein the term “mixed polymer waste” refers to waste material that comprises a mixture of different types or classes of polymer. For example, mixed polymer waste might comprise a mixture of polyethylene, and polyethylene terephthalate or a mixture of polyethylene, polyethylene terephthalate and polyamide.

[0027] As used herein the term “post consumer plastic waste” refers to mixed polymer waste produced by an end consumer. A typical example of post consumer plastic waste is packaging.

[0028] As used herein the term “plastic waste” refers to waste comprising one or more polymers and additives.

[0029] As used herein the term “polyolefin” refers to polymers with a saturated C-C backbone and which consist of C and H atoms.

[0030] As used herein the term “ polymer” refers to one or more polymers.

[0031] As used herein the term “compounds comprising heteroatoms” refers to non- polymeric compounds and polymers which contain N, O, P and / or S atoms.

[0032] As used herein the term “polymer comprising heteroatoms” refers to one or more polymers which contain N, O, and / or S atoms. Polyvinyl chloride is not a polymer comprising such heteroatoms.

[0033] As used herein the term “non-oligomeric compounds comprising heteroatoms” refers to compounds such as additives which contain N, O, P and / or S atoms.

[0034] As used herein the term “polyethylene” refers to a polymer having the repeat unit -(CH2CH2)-. Preferably at least 80 %wt, more preferably at least 95 %wt, still more preferably at least 99 %wt of the repeat units in polyethylene are -(CH2CH2)-. Other repeat units that may be present include -(CH2CHR)- wherein R is C1-6 alkyl. The term encompasses low density polyethylene (LDPE), high density (HDPE), cross-linked polyethylene and linear low density polyethylene (LLDPE).

[0035] As used herein the term “polypropylene” refers to a polymer having the repeat unit -(CH(CH3)CH2)-. Preferably at least 85 %wt, more preferably at least 95 %wt and still more preferably at least 99 %wt of the repeat units in polypropylene are - (CH(CH3)CH2)-. The term encompasses all different forms of polypropylene, e.g. homopolymers, propylene heterophasic copolymer and propylene random copolymer. All kinds of tacticity is also covered.

[0036] As used herein the term “polyethylene terephthalate” refers to a polymer having an ethylene terephthalate repeating unit (C10H8O4). This is typically formed from monoethylene glycol and terephthalic acid. Preferably at least 95 %wt, more preferably at least 99 %wt of the repeat units in polyethylene terephthalate are ethylene terephthalate (C10H8O4). Optionally repeat units derived from other diols (e.g. 2-methyl- 1 ,2-propanediol, diethyleneglycol, cyclohexane dimethanol, 1 ,3-propanediol, 1 ,4- propanediol) and / or iso-terephthalic acid may also be present.

[0037] As used herein the term “polyamide” refers to a polymer having repeating units linked by amide bonds. The term encompasses aliphatic polyamides such as Nylon PA- 6 and PA-66, aromatic amides (sometimes referred to as aramids) as well as polyphthalamides Preferably at least 95 %, and more preferably at least 99 % of the bonds linking repeat units in polyamides are amides.

[0038] As used herein, the term “pyrolysis product” refers to the hydrocarbon mixture obtained from the fluidised bed reactor where pyrolysis takes place.

[0039] As used herein, the temperature referred to in the phrase “pyrolysis is carried out at a temperature” is the temperature of the fluidised bed.

[0040] As used herein, the pressure referred to in the phrase “pyrolysis is carried out at a pressure” refers to the pressure in the fluidised bed reactor, as measured by a transducer.

[0041] As used herein, the terms “degassing unit” and “devolatization unit” are used interchangeably.

[0042] DETAILED DESCRIPTION OF THE INVENTION

[0043] The present invention relates to a method for producing a pyrolysis product from mixed polymer waste, wherein said mixed polymer waste comprises 50-99.5 wt% polyolefins and 0.5-50 wt% polymer comprising heteroatoms, based on the total weight of the mixed polymer waste, comprising: (i) feeding said mixed polymer waste into an extruder, preferably a single screw extruder;

[0044] (ii) adding chemicals, preferably alkali metal salt and / or alkali earth metal salt, to said mixed polymer waste to degrade said compounds, preferably polymer, comprising heteroatoms;

[0045] (iii) removing degradation products derived from said compounds, preferably polymer, comprising heteroatoms from said hydrocarbon product; and

[0046] (iv) pyrolysing the hydrocarbon product in a fluidised bed reactor to obtain pyrolysis product.

[0047] The method of the present invention can advantageously be used in a recycling process to convert the mixed polymer waste into a form that can re-enter the refinery value chain. Typically, the mixed polymer waste is plastic waste. The mixed polymer waste is preferably post consumer plastic waste (PCW).

[0048] One of the main advantages of the method of the present invention is that the mixed polymer waste may contain relatively high levels of heteroatom-containing polymers and / or non-polymeric heteroatom-containing compounds, such as additives, e.g. up to 50 wt%. This is ten times more than commercial recycling plants currently in operation, and avoids the need to mechanically separate different classes of polymer. This is because the first step of the method of the invention degrades the heteroatomcontaining compounds, e.g. polymer and / or non-oligomeric compounds such as additives, and many of the degradation products can be removed from the reaction mixture before pyrolysis is carried out. Further heteroatom-containing compounds are removed during the pyrolysis.

[0049] Optionally the degradation products can be recovered. Optionally the degradation products are useful chemicals, e.g. monomers and / or monomer derivatives. Recovery of the degradation products is particularly advantageous in such cases. At the same time, the first step of the method of the invention advantageously causes initial cracking of the polyolefins and produces a more homogeneous, and less viscous, melt thereby facilitating its processing to the pyrolysis reactor and the pyrolysis reaction itself.

[0050] The pyrolysis reaction is carried out in a fluidised bed reactor in relatively mild conditions. In particular, the pyrolysis reaction is conducted at relatively low temperatures and for a relatively short residence time. This is possible due to the quality of the hydrocarbon product obtained from the extrusion step, and is highly advantageous as it reduces the extent of secondary reactions that occurs during pyrolysis. The pyrolysis reaction also reduces the amount of heteroatom-containing compounds present to even lower levels so the pyrolysis product obtained may require less upgrading before entering the refinery value chain.

[0051] The extrusion in the method of the present invention is predominantly based on a chemical degradation reaction, e.g. hydrolysis, of the heteroatom-containing compounds e.g. polymer and / or non-polymeric compounds such as additives. This is preferable over thermal degradation of these compounds because it is controlled, and gives rise to known degradation compounds, which can be removed from the polymer melt before the melt enters the pyrolysis reactor. This avoids the formation of corrosive or harmful substances such as acids and cyanides. Optionally, degradation products, e.g. inorganics, can additionally be removed in the pyrolysis step.

[0052] As mentioned above, the quality of the hydrocarbon product obtained from the extrusion allows for the pyrolysis reaction to be carried out at temperatures of about 400- 650 °C, and for short residence times of 4-120 seconds. The resulting pyrolysis product is significantly improved in terms of purity and homogeneity, i.e. it is more consistent in terms of hydrocarbon composition than the mixed polymer waste. Moreover, the method of the present invention may achieve a very high total recovery of mass, e.g. greater than 90 %wt based on the weight (solids) of the mixed polymer waste feedstock.

[0053] Finally, the method of the present invention reduces or avoids the need for complicated, and expensive, purification steps that are not normally, or currently, available at hydrotreatment facilities to clean up the post-pyrolysis hydrocarbon product, and allows for improved pyrolysis control. Moreover, the method of the invention additionally minimises the presence of inorganic contaminants in the post-pyrolysis hydrocarbon product.

[0054] Mixed polymer waste

[0055] The mixed polymer waste processed in the method of the present invention is preferably plastic waste, and more preferably post consumer plastic waste.

[0056] The mixed polymer waste that is processed in the method of the present invention is predominantly polyolefin. Thus the major component of the mixed polymer waste should be polyolefin. In preferred methods of the present invention, the mixed polymer waste comprises 50-99 wt% polyolefins, more preferably 65-98 wt% polyolefins, and yet more preferably 70-95 wt% polyolefins, based on the total weight of the mixed polymer waste composition.

[0057] In a preferred method of the invention, the polyolefins present in the mixed polymer waste are selected from polyethylene (e.g. LDPE, HDPE, LLDPE), polypropylene, polystyrene and mixtures thereof. In some preferred methods of the invention the polyolefins present in the mixed polymer waste comprise, or consist of, polyethylenes. In other preferred methods of the invention the polyolefins present in the mixed polymer waste comprise, or consist of, polypropylenes. Preferably the mixed polymer waste comprises less than 10 wt%, more preferably 0-10 wt%, still more preferably 0-5 wt% and yet more preferably 0-2 wt% polyvinyl chloride.

[0058] In preferred methods of the invention the mixed polymer waste comprises 1-50 wt%, more preferably 2-35 wt% and yet more preferably 5-30 wt% compounds, e.g. polymer, comprising heteroatoms, based on the total weight of the mixed polymer waste composition. This is highly advantageous as it avoids the need to try to mechanically separate different polymer classes prior to carrying out the method of the invention. Mechanical separation is commonplace in recycling operations currently in use but achieves only modest levels of separation.

[0059] The heteroatoms present in the heteroatom-containing compounds, e.g. polymer, are preferably selected from N, O, S, and P, and more preferably N, O and S. More preferably the compounds, e.g. polymer, comprising heteroatoms comprise N and / or O atoms.

[0060] In preferred methods of the present invention the compounds comprising heteroatoms in the mixed polymer waste are selected from non-polymeric compounds, polymers, and mixtures thereof. Whilst the method of the present invention advantageously removes non-polymeric heteroatom-containing compounds, it is particularly beneficial for removal of heteroatom-containing polymers. This is because the polymers tend to contain higher amounts of heteroatoms than the non-polymeric compounds, and also because the polymers tend to be present in mixed polymer waste in higher amounts. This is because such polymers are a key component of, e.g. multilayered packaging film.

[0061] When the mixed polymer waste comprises non-polymeric compounds comprising heteroatoms, the non-polymeric compounds are preferably additives, and more preferably additives selected from antioxidants, acid scavengers, slip agents, anti-block agents, processing aids, fillers, extenders, pigments, nucleation agents, lubricants, antistatic agents, UV stabilisers, anti-fogging agents, flame retardants, and mixtures thereof. Representative examples of heteroatom-containing additives that may be present in mixed polymer waste include tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4- di-tert-butylphenyl)pentaerythritol diphosphate, octadecyl 3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate), 1 ,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4- hydroxybenzyl)benzene, tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, a- tocopherol (Vitamin E), calcium stearate, zinc stearate, hydrotalcite, synthetic, cis-13- docosenoamide, oleamide, LUDOX® CL colloidal silica, magnesium silicate monohydrate, titanium(IV) oxide, limestone, magnesium silicate monohydrate, 1 , 3:2,4- bis(3,4-dimethylobenzylideno) sorbitol, 1 ,2,3-trideoxy-4,6:5,7-bis-O-((4- propylphenyl)methylene)-nonitol, glyceryl monostearate, 2,2'-iminobis-, N-C12-18-alkyl derivatives, and mixtures thereof.

[0062] In preferred methods of the present invention, the compounds comprising heteroatoms are polymers. Preferably the heteroatom containing polymers comprise repeating units, derived from monomers, which contain heteroatoms. Preferred heteroatom-containing polymers are those having repeating units joined by amide bonds, ester bonds, carbamate bonds, carbonate bonds, or mixtures thereof. In the conditions of the present invention, specifically the extrusion step, these bonds are preferably hydrolytically degraded and the heteroatom-containing polymer is degraded to degradation products that can be removed from the polymer melt.

[0063] In preferred methods of the present invention, the compounds comprising heteroatoms are polymers selected from polyethylene terephthalate (PET), polyamide (PA), polyurethane (PU), biopolymers (e.g. polylactic acid, polyhydroxyalkanoates), cellulose, poly(ethylene-co-vinyl acetate) (EVA), poly( vinyl alcohol-co-ethylene) (EVOH), polycarbonate, poly(acrylonitrile-co-butadiene-co-styrene) (ABS), poly(styrene- co-acrylonitrile) (SAN), polymethylmethacrylate (PMMA) and mixtures thereof. Preferably the compounds comprising heteroatoms are polymers selected from polyethylene terephthalate (PET), polyamide (PA), polyurethane (PU), biopolymers (e.g. polylactic acid, polyhydroxyalkanoates and mixtures thereof). Another possible biopolymer comprising heteroatoms is polyethylene furanoate (PEF). Still more preferably the compounds comprising heteroatoms are polymers selected from polyethylene terephthalate (PET), polyamide (PA), and mixtures thereof. In some preferred methods of the invention mixtures of PET and PA are preferred.

[0064] In the method of the present invention the polymers may be virgin material or may be, e.g. plastic waste or post consumer plastic waste (PCW). The polymers may also be a mixture of virgin material and plastic waste or PCW.

[0065] In preferred methods of the present invention, the mixed polymer waste is washed (e.g. with water) prior to step (i) of the method herein described. Conventional methods may be used. For example, the mixed polymer waste may be washed with hot (e.g. 80-90 °C) or cold (e.g. 20-25 °C) water, optionally using detergents and / or caustic soda, particularly if the waste contains fatty residues, e.g. deriving from food contact applications. The skilled person is well aware of suitable washing conditions.

[0066] In the methods of the present invention the mixed polymer waste is optionally treated prior to step (i) of the method described herein to remove any aluminium present. Such aluminium can be present if the mixed polymer waste includes, e.g. films with a barrier layer.

[0067] Preferably the mixed polymer waste is also treated to remove materials that might damage the processing equipment (e.g. metal, stones, glass etc) prior to step (i) of the method herein described. Washing and separation to remove bulk contaminants may be carried out using conventional equipment. Advantageously, the mixed polymer waste does not need to undergo mechanical separation into different polymer types prior to step (i) of the method described herein.

[0068] Optionally the mixed polymer waste is dried prior to step (i) of the method described herein. Advantageously, the mixed polymer waste does not need to undergo extensive drying to remove water prior to step (i). The mixed polymer waste may, for example, comprise 0-20 wt% water, more preferably 2-18 wt% water and still more preferably 5 to 12 wt% water prior to step (i).

[0069] The mixed polymer waste is preferably in the form of pellets, agglomerates or flakes. Pellets and agglomerates are preferred. The conversion of mixed polymer waste into pellets and / or agglomerates may be carried out using any type of physical processing such as chopping, crushing, grinding, shredding, etc. It may also be advantageous, in some circumstances, to carry out processing to reduce the average particle size of pellets and / or agglomerates.

[0070] In preferred methods of the present invention, the mixed polymer waste is shredded or cut prior to entry into the method of the present invention. Conventional equipment may be used. In preferred methods of the invention the bulk density of the mixed polymer waste is increased prior to step (i) of the method herein described. This may be achieved by, e.g. compacting or agglomeration of flakes, cut or shredded mixed polymer waste. Preferably the bulk density of the mixed polymer waste fed into step (i) of the method described herein is 50-850 kg / m3and more preferably 300-820 kg / m3. This ensures that a more consistent amount of material can be fed through the process.

[0071] In preferred methods of the present invention, the mixed polymer waste is HDPE monomaterial, artificial turf (PE), flexible intermediate bulk containers (FIBC, PE / PP), or multi-layered film. The mixed polymer waste may also be end-of-life recycled material, unsuitable for further mechanical recycling. The mixed polymer waste may come from a range of industries, e.g. fishing, farming, marine, building and construction, food and drink, packaging, energy, battery manufacture and so on, In particularly preferred methods of the invention, the mixed polymer waste is multi-layered packaging film. Preferably the multi-layered film is shredded or cut into granules or flakes, and then compacted or agglomerated for entry into the method of the present invention. Thus a preferred method of the invention comprises a prior step of shredding or cutting the mixed polymer waste into flakes. Preferably the flakes have an average dimension of 3- 8 mm, more preferably 3-5 mm. In a further preferred method of the invention the flakes are compacted or agglomerated to a bulk density of 300-850 kg / m3prior to step (i) of the method described herein.

[0072] Process conditions

[0073] In step (i) of the method of the present invention the mixed polymer waste is fed into an extruder. During its time in the extruder, two key processes occur. First the polyolefin present in the mixed polymer waste undergoes cracking to produce a hydrocarbon product in the form of a melt. Second the heteroatom-containing compounds, i.e. polymer and / or non-polymeric compounds such as additives, present in the mixed polymer waste undergo degradation to produce degradation products that can be removed from the hydrocarbon melt.

[0074] In some preferred methods of the present invention, the mixed polymer waste is mixed with water prior to feeding said mixed polymer waste to the extruder. The water may be in the form of a liquid or gas (i.e. steam). The water is a chemical in the method of the invention and may be beneficial for the hydrolysis reaction that degrades the heteroatom-containing polymer and / or non-polymeric compounds containing heteroatoms such as additives. Preferably the water is provided as an alkaline or acidic solution, and more preferably an alkaline solution. Mixing of the mixed polymer waste with an acid oralkali promotes the degradation of the heteroatom-containing compounds, i.e. polymer and / or non-polymeric compounds such as additives, by chemical degradation, rather than thermal degradation. As mentioned above, this gives rise to stable degradation products that can then be removed from the hydrocarbon product.

[0075] In other preferred methods of the invention, the mixed polymer waste is not mixed with water prior to feeding said mixed polymer waste to the extruder. These methods are preferred, for example, when the mixed polymer waste already contains sufficient water for the hydrolysis reaction. In such methods, the mixed polymer waste and solid chemicals, preferably alkali metal salt and / or alkali earth metal salt, are mixed prior to feeding the resulting mixture to the extruder.

[0076] In other preferred methods of the invention, water is optionally added to the mixed polymer waste in the extruder. The water may be in the form of a liquid or gas (i.e. steam). In these methods, the mixed polymer waste is fed into the extruder, and water is added separately. Preferably the water is an alkaline solution. Optionally, the alkaline solution is injected into the extruder (e.g. using a high pressure dosing pump). The alkaline solution may be injected at one or multiple locations.

[0077] In more preferred methods of the invention, the chemicals added to the mixed polymer waste are an alkali metal salt and / or an alkaline earth metal salt. Examples of preferred salts are alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal oxides, alkaline earth metal oxides, alkali metal carbonates, alkaline earth metal carbonates or mixtures thereof. Alkali metal carbonates, alkaline earth metal carbonates or mixtures thereof are particularly preferred. These may be added in the form of an alkaline solution. Alternatively, e.g. when there is sufficient water in the mixed polymer waste, they may be added as solids.

[0078] In some preferred methods of the present invention the chemicals added to the mixed polymer waste are an alkaline solution. Preferably the alkaline solution is selected from ammonia solutions, and solutions of alkali metal or alkaline earth metal hydroxides, alkali metal or alkaline earth metal oxides, alkali metal or alkaline earth metal carbonates or mixtures thereof.

[0079] In other preferred methods of the present invention, the chemicals added to the mixed polymer waste are solid alkali metal salts and / or alkaline earth metal salts.

[0080] In some preferred methods of the present invention, the mixture of water and mixed polymer waste comprises 0.5-15 wt% water, more preferably 0.5-12 wt% water and still more preferably 8-12 wt% or 8-10 wt% water, based on the total weight of the mixture. The amount of water present depends on the amount of water present in the mixed polymer waste itself and, the amount of water (if any) added. It will also be appreciated that the amount of water in the mixture may vary slightly at the inlet of the extruder and in the extruder itself. These values preferably represent the amount of water present in the mixture of water and mixed polymer waste in the extruder, where degradation occurs. The presence of higher amounts of water (e.g. > 5wt%) has been found to be particularly useful when the heteroatom-containing compound is PET.

[0081] In preferred methods of the present invention, the mixture of water, alkali metal salt and / or alkaline earth metal salt, and mixed polymer waste is thoroughly mixed prior to feeding it into the extruder. This helps to ensure efficient removal of the heteroatomcontaining compounds therein, particularly heteroatom-containing polymers and / or compounds such as additives. In preferred methods of the invention, the mixture of water, alkali metal salt and / or alkaline earth metal salt, and mixed polymer waste is all fed into the extruder, i.e. no water is removed prior to entry into the extruder.

[0082] In preferred methods of the present invention, the extruder is operated at unconventionally high temperatures. It has been found this yields the highest quality hydrocarbon products (e.g. lowest wt% heteroatom-containing compounds in the product). Preferably the extruder is at a temperature of at least 300 °C, preferably 300- 400 °C, still more preferably 350-395 °C and yet more preferably 370-395 °C. A further advantage of operating the extruder at such a high temperature is that the temperature of the hydrocarbon product that exits the extruder is also high, and the amount of further heating it needs to enter the pyrolysis reactor is significantly reduced. Advantageously, the difference in temperature between the hydrocarbon product exiting the extruder and the temperature of the fluidised bed reactor is 50-200 °C, more preferably 60-160 °C and still more preferably 70-130 °C.

[0083] In the methods of the present invention, the extruder may be operated at a pressure of up to 400 bar, and more preferably 0 to 200 bar. Whilst in some preferred methods of the invention, no pressure is applied in the extruder, in other preferred methods, a pressure of 50-200 bar is used.

[0084] In preferred methods of the invention (e.g. using a single screw extruder) the residence time of the mixed polymer waste in said extruder is 0.1 to 20 minutes, preferably 0.5-15 minutes, more preferably 0.5 to 10 minutes, still more preferably 1 to 7 minutes and yet more preferably 1.5 to 5 minutes. In further preferred methods of the invention (e.g. if a twin extruder is used) the residence time of the mixed polymer waste in said extruder is 0.1-20 minutes, preferably 0.5-15 minutes, more preferably 0.5 to 10 minutes, still more preferably 0.5 to 7 minutes and yet more preferably 0.5 to 5 minutes. The short residence time in the extruder is beneficial since it means large volumes of mixed polymer waste can be pre-treated in any given time period. At the same time, the polyolefin present in the mixed polymer waste is at least partially cracked. Preferably the average molecular weight and viscosity of the hydrocarbon product is reduced, and the MFR2 of the hydrocarbon product is increased compared to the polyolefin present in the mixed waste starting material. The first step of the method of the invention represents a fast, and efficient, mechanism for preparing ideal feedstock for pyrolysis from mixed polymer waste, that otherwise could not undergo pyrolysis. The residence time in the extruder is dependent on the scale (e.g. length and diameter) and screw design of the extruder as well as the RPM at which it is operated. In preferred methods of the invention, the RPM is set to ensure the afore-mentioned residence times are satisfied for the particular extruder in use. For a single screw extruder, with a diameter of 25 mm, a length / diameter ratio of 25, the RPM is preferably 10-200, more preferably 10-100 and still more preferably 12-60 RPM, e.g. about 20 RPM. For a twin screw extruder, with a screw diameter of 18 mm, a length / diameter ratio of 60, the RPM is preferably 60-200 RPM, more preferably 80-160 RPM and still more preferably 100-140 RPM. The skilled person can readily identify equivalent RPMs for extruders of different scale and / or screw design to ensure the feed rate requirements and residence time requirements are satisfied.

[0085] In preferred methods of the present invention, different compounds, e.g. polymers and non-polymeric compounds, comprising heteroatoms are simultaneously degraded in the extruder. Preferably non-polymeric compounds such as additives are also simultaneously degraded in the extruder. Thus preferably the polymers and / or non- polymeric compounds such as additives, both comprising heteroatoms, are all degraded in a single pass through the extruder. This is highly advantageous as it means that a single pass through the extruder simultaneously deals with the majority of the different heteroatom-containing compounds, i.e. polymer and non-polymeric, present in mixed plastic waste. It is clearly much more time, energy and cost efficient compared to processes wherein each contaminant type is dealt with separately. In a particularly preferred method of the invention, a mixture of heteroatom-containing polymers is simultaneously degraded in the extruder. Still more preferably a mixed polymer waste comprising PET and PA as heteroatom-containing polymers is simultaneously degraded in the extruder.

[0086] In the methods of the invention the extruder may be a commercially available extruder. The extruder may have a twin screw or a single screw. In some conditions, single screw extruders are preferred. In other conditions, twin screw extruders are preferred.

[0087] Preferably the screw diameter is in the range 14 mm-125 mm. Preferably the length / diameter ratio is 15-60, and is configured with single-stage or two-stage screws. The screw(s) may be a standard screw, a barrier screw, or a screw equipped with elements such as metering zones, mixing elements, kneading zones and back flow elements. The screw(s) and barrel may be conically shaped or standard cylinder-shaped with equal diameter. Optionally the barrel may be equipped with inlets for additional of chemicals (e.g. alkali metal salt and / or alkaline earth metal salt) and / or steam, such as in a mixing zone or feeding zone.

[0088] In some preferred methods of the invention, the barrel comprises a devolatilization outlet. This allows degradation products in the form of volatiles to escape from the extruder. Alternatively, degradation products in the form of volatiles may escape through the extruder die. Optionally the extruder may be operated with a vacuum at its exit, in order to encourage volatile degradation products to escape through the extruder die. Thus in some preferred methods of the invention, the degradation products derived from the compounds comprising heteroatoms (e.g. polymer and / or non-polymeric compounds) are removed in the form of volatiles and via a devolatization outlet of the extruder or through the extruder die.

[0089] In other preferred methods of the invention, the extruder is connected to a downstream devolatilization unit. In such methods, the volatiles produced by degradation of heteroatom-containing compounds, e.g. polymer and / or non-polymeric compounds such as additives, remain in the hydrocarbon product that exits the extruder, and is fed to a devolatilization unit (e.g. a degasser unit). Thus in other preferred methods of the invention, the degradation products derived from the polymer and / or non- polymeric compounds comprising heteroatoms are removed in the form of volatiles and via a devolatization unit, e.g. a degassing unit. Preferably the devolatization unit or degassing unit is connected to the extruder exit, or if present, a melt filter.

[0090] In some preferred methods of the invention, a stripping agent is used. Examples of stripping agents include nitrogen, steam and carbon dioxide. Preferably, the stripping agent diffuses through the polymer melt in the extruder, increasing the polymer-vapour interface, and thereby increasing the removal of degradation products in the form of volatiles. The stripping agent may be introduced into the extruder using any conventional means.

[0091] In further preferred methods of the invention, the hydrocarbon product collected or exited from the extruder is passed through a melt filter. When a melt filter is present, the extruder is preferably operated under pressure, as discussed above. Preferably the melt filter is directly connected to the outlet of the extruder. Preferably the melt filter removes the solid degradation products (e.g. salts) produced in the extruder from the heteroatom-containing compounds as well as any non-dissolvable residues deriving from the mixed polymer waste (e.g. Al foil, etc). Thus in some preferred methods of the invention, the degradation products derived from the polymer and / or non-polymeric compounds comprising heteroatoms are removed in the form of solids and via a melt filter. Preferably the melt filter is directly connected to the extruder exit.

[0092] In preferred methods of the present invention, the solid degradation products produced in the extruder from the heteroatom-containing compounds are collected. Optionally these products are separately recycled.

[0093] Preferably the melt filter also removes other solid contaminants present in the mixed polymer waste, e.g. metal, wood, fibres etc. Small amounts of solid contaminants sometimes remain in the mixed polymer waste due to deficiencies in the clean-up processes carried out prior to the method of the present invention. Preferably these solid contaminants are removed in the melt filter, and do not enter the pyrolysis reactor.

[0094] In particularly preferred methods of the invention, the hydrocarbon product collected or exited from the extruder is passed through a melt filter and then to a devolatilization unit (e.g. a degasser unit). In the devolatilization unit, volatile products produced in the extruder from the heteroatom-containing compounds are preferably collected. These include heteroatom-containing gases as well as low molecular weight hydrocarbons. Preferably these gases are collected and condensed to liquid or solid form. Optionally, these products are separately recycled.

[0095] Advantageously the devolatilization unit can also function as a buffer tank for polymer melt to overcome fluctuations in feed rate to the fluidised bed reactor. Feed rate fluctuations can sometimes arise due to variation in the bulk density of the polymer waste feedstock and / or the extent of devolatilization achieved.

[0096] Thus in some preferred methods of the invention, the degradation products derived from the polymer and / or non-polymeric compounds comprising heteroatoms are removed via a melt filter and / or a devolatilization or degassing unit. Preferably the melt filter is directly connected to the extruder exit. Preferably the devolatilization unit is directly connected to the extruder exit, or if present, the melt filter.

[0097] In particularly preferred methods of the invention, the degradation products are recovered and optionally recycled. Preferably the degradation products comprise monomers derived from heteroatom-containing polymers.

[0098] In some preferred methods of the invention, the hydrocarbon product is collected from the extruder, or if present, the melt filter or devolatilization unit. Optionally, the hydrocarbon product is processed, e.g. to form granulates or pellets.

[0099] Product In the method of the present invention the hydrocarbon product produced is suitable for pyrolysis.

[0100] In preferred methods of the present invention the hydrocarbon product comprises 0-5 wt%, more preferably 0-3 wt%, still more preferably 0-2 wt% and yet more preferably 0-1 wt% polyethylene terephthalate (PET), based on the total weight of the hydrocarbon product. Still more preferably the hydrocarbon product comprises 0-5 wt%, more preferably 0-3 wt%, still more preferably 0-2 wt% and yet more preferably 0-1 wt% PET degradation products, based on the total weight of the hydrocarbon product. Preferably the amount of PET and PET degradation products present in the hydrocarbon product is assessed as described in the examples herein.

[0101] In a further preferred methods of the invention, the hydrocarbon product comprises 0-5 wt%, more preferably 0-3 wt%, still more preferably 0-2 wt% and yet more preferably 0-1 wt% polyamide (PA), based on the total weight of the hydrocarbon product. Still more preferably the hydrocarbon product comprises 0-5 wt%, more preferably 0-3 wt%, still more preferably 0-2 wt% and yet more preferably 0-1 wt% polyamide (PA) and PA degradation products, based on the total weight of the hydrocarbon product. Preferably the amount of PA and PA degradation products present in the hydrocarbon product is assessed as described in the examples herein.

[0102] In a further preferred method of the invention the hydrocarbon product comprises 0-10 wt%, more preferably 0-8 wt%, still more preferably 0-4 wt% and yet more preferably 0-2 wt% compounds comprising heteroatoms, based on the total weight of the hydrocarbon product. Preferably the total amount of compounds comprising heteroatoms present in the hydrocarbon product is assessed by HCNSO ultimate analysis for elemental composition.

[0103] In a further preferred method of the invention the hydrocarbon product comprises: 0-5 wt%, more preferably 0-3 wt%, still more preferably 0-2 wt% and yet more preferably 0-1 wt% polyethylene terephthalate (PET) and / or PET degradation products;

[0104] 0-5 wt%, more preferably 0-3 wt%, still more preferably 0-2 wt% and yet more preferably 0-1 wt% polyamide (PA) and / or PA degradation products; and optionally 0-10 wt%, more preferably 0-8 wt%, still more preferably 0-4 wt% and yet more preferably 0-2 wt% compounds comprising heteroatoms, based on the total weight of the hydrocarbon product.

[0105] As described above, in the first step of the method of the present invention, the polyolefins present in the mixed polymer waste undergo cracking in the extruder. This is advantageous for a variety of reasons, including that the hydrocarbon product is easier to feed to a pyrolysis unit, and is an improved feedstock for a pyrolysis unit. Aside from containing fewer compounds comprising heteroatoms, the hydrocarbon product is much more homogeneous than the mixed polymer waste, which leads to better thermal conduction and heat transfer in the pyrolysis unit.

[0106] Preferably the hydrocarbon product has a lower weight average molecular weight than the mixed polymer waste. Preferably the weight average molecular weight of the hydrocarbon product is 1-95 %, more preferably 1-85 % and still more preferably 1-50 % of the weight average molecular weight of the mixed polymer waste. The decreased weight average molecular weight of the hydrocarbon product is evidence that cracking occurs in the extruder.

[0107] When the mixed polymer waste predominantly comprises LLDPE, the hydrocarbon product has a weight average molecular weight of 5000-100000 g / mol, more preferably 5000-50000 g / mol and still more preferably 5000-32000 g / mol.

[0108] When the mixed polymer waste predominantly comprises LDPE, the hydrocarbon product has a weight average molecular weight of 5000-65000 g / mol, more preferably 5000-58000 g / mol and still more preferably 5000-35000 g / mol.

[0109] When the mixed polymer waste predominantly comprises HDPE, the hydrocarbon product has a weight average molecular weight of 5000-190000 g / mol, more preferably 5000-135000 g / mol and still more preferably 5000-60000 g / mol.

[0110] When the mixed polymer waste predominantly comprises PP, the hydrocarbon product has a weight average molecular weight of 5000-130000 g / mol, more preferably 5000-90000 g / mol and still more preferably 5000-50000 g / mol.

[0111] Another advantage of the method of the invention is that the viscosity of the hydrocarbon product is lower than that of the mixed polymer waste. This is beneficial as it makes it much easier to feed the hydrocarbon product into the pyrolysis unit, i.e. the processing of the hydrocarbon product is facilitated. Preferably the hydrocarbon product has a lower complex viscosity, Eta (0.5) than the mixed polymer waste. Preferably the hydrocarbon product has a lower complex viscosity, Eta (200) than the mixed polymer waste.

[0112] Preferably the hydrocarbon product has a complex viscosity r , Eta (0.5) of 0. OSS %, more preferably 0.05-10 % and still more preferably 0.05-1 % of the complex viscosity, Eta (0.5) of the mixed polymer waste.

[0113] Preferably the hydrocarbon product has a complex viscosity q*, Eta (200) of 0.01- 60 %, more preferably 0.05-10 % and still more preferably 0.05-1 % of the complex viscosity, Eta (200) of the mixed polymer waste. When the mixed polymer waste predominantly comprises LLDPE, preferably the hydrocarbon product has a complex viscosity, Eta (0.5) of 2-1500 Pa*s, more preferably 2-200 Pa*s and still more preferably 2-20 Pa*s.

[0114] When the mixed polymer waste predominantly comprises LLDPE, preferably the hydrocarbon product has a complex viscosity, Eta (200) of 1-330 Pa*s, more preferably 1-50 Pa*s and still more preferably 1-5 Pa*s.

[0115] Preferably the hydrocarbon product has a higher MFR2 than said mixed polymer waste. Preferably the hydrocarbon product has a MFR2 which is at least 150 %, more preferably 150-100,000 % and still more preferably 500-30,000 % of the MFR2 of the mixed polymer waste.

[0116] When the mixed polymer waste predominantly comprises LLDPE, preferably the hydrocarbon product has a MFR2 of at least 0.2 g / 10 min More preferably when the mixed polymer waste predominantly comprises LLDPE, the hydrocarbon product has a MFR2 of at least 1 g / 10 min, more preferably 1-800 g / 10 min, still more preferably 100- 800 g / 10 min and yet more preferably 200-800 g / 10 min.

[0117] When the mixed polymer waste predominantly comprises LDPE, preferably the hydrocarbon product has a MFR2 of at least 0.2 g / 10 min. More preferably when the mixed polymer waste predominantly comprises LDPE, the hydrocarbon product has a MFR2 of at least 1 g / 10 min, more preferably 1-800 g / 10 min, still more preferably 100- 800 g / 10 min and yet more preferably 200-800 g / 10 min.

[0118] When the mixed polymer waste predominantly comprises HDPE, preferably the hydrocarbon product has a MFR2 of at least 0.2 g / 10 min. More preferably when the mixed polymer waste predominantly comprises HDPE, the hydrocarbon product has a MFR2 of at least 1 g / 10 min, more preferably 1-800 g / 10 min, still more preferably 100- 800 g / 10 min and yet more preferably 200-800 g / 10 min.

[0119] When the mixed polymer waste predominantly comprises PP, preferably the hydrocarbon product has a MFR2 of at least 1 g / 10 min, more preferably 3-800 g / 10 min, still more preferably 150-800 g / 10 min and yet more preferably 200-800 g / 10 min.

[0120] Preferably the hydrocarbon product is substantially free of cross linking.

[0121] Pyrolysis

[0122] In the method of the present invention, the hydrocarbon product obtained from the above-described extrusion is fed to a pyrolysis unit. The hydrocarbon product may be transferred to the pyrolysis unit by a transfer conduit. Optionally the transfer conduit may be heated to assist with maintaining the hydrocarbon product at a high temperature and in the liquid state. Optionally the transfer conduit may include an extruder. Such an extruder may, for example, feed the hydrocarbon product into the pyrolysis unit.

[0123] The method of the invention is advantageous because the quality of this hydrocarbon product as a pyrolysis feedstock is significantly improved compared to the mixed polymer waste. For example, it is much more homogeneous in terms of composition, and it contains far fewer heteroatom-containing compounds that cause damage to pyrolysis equipment and lead to production of hazardous and corrosive substances. As a result, the pyrolysis reaction carried out after the process of the present invention is also much improved.

[0124] The pyrolysis is carried out in a fluidised bed reactor. Any conventional fluidised bed reactor may be used. For example, a bubbling fluidised bed reactor may be used.

[0125] The hydrocarbon product from step (iii) of the method of the invention may be collected and then fed to a fluidised bed reactor for pyrolysis. In this case, the hydrocarbon product from step (iii) may be fed to the fluidised bed reactor by, e.g. an extruder or by spraying.

[0126] Alternatively and preferably the hydrocarbon product from step (iii) of the method of the invention is fed directly to a fluidised bed reactor for pyrolysis. The product may be fed to the fluidised bed reactor by any conventional means. However, spraying is preferred. As mentioned above, preferably the temperature difference between the hydrocarbon product and the fluidised bed reactor is minimised, e.g. the difference is 50- 200 °C, more preferably 60-160 °C and still more preferably 70-130 °C to avoid temperature cycling.

[0127] The hydrocarbon product may be fed into the fluidised bed reactor in any orientation. For example, the hydrocarbon product may be fed into the reactor substantially horizontally relative to the vertical orientation of the fluidised bed. The feed position of the hydrocarbon product relative to the height of fluidised bed may be, for example, within the height of the fluidised bed, or below the height of the fluidised bed. Any conventional arrangement may be used.

[0128] Preferably the pyrolysis is carried out at a temperature of 400-650 °C, preferably 420-600 °C and more preferably 450-550 °C. As mentioned above, an advantage of the method of the present invention is that pyrolysis is carried out at relatively low temperatures. This is beneficial because it minimises the amount of secondary reactions such as isomerisation and aromatisation that occur. As a result, the pyrolysis product is obtained in high mass yield (relative to the mixed polymer waste feedstock) and in high quality, e.g. as assessed by PIONA. Preferably the pyrolysis is carried out at a pressure of 0.2-3.0 Barg and preferably 0.5-2.2 Barg. Pressure in the fluidised bed reactor is created by the flow of inert gas into the reactor, which keeps the hydrocarbon product being fed into the reactor fluidised, and by gases present in the hydrocarbon product and in the pyrolysis product generated in the reactor. Preferably the flow rate of nitrogen, and the feed rate of hydrocarbon product is maintained at levels to enable the above-mentioned pressures to be maintained. Any plugging in the inlet lines into the reactor, or in the outlet lines out of the reactor, due to high viscosity product causes pressure to increase. For example if there is too much PA present in the hydrocarbon product undesirable side reactions, e.g. cross linking, can occur in the elevated temperatures of the fluidised bed reactor, and produce high viscosity product that plugs the outlet lines. This increases pressure. Such problems are avoided in the method of the invention because the first step of extrusion decreases the level of compounds, including polymers, comprising heteroatoms in the hydrocarbon product fed to the fluidised bed reactor where pyrolysis takes place.

[0129] In a preferred method of the invention, pyrolysis of the hydrocarbon product is in a fluidised bed reactor wherein the fluidised bed comprises heat carrier particles. The heat carrier particles may be inert, active or a mixture thereof. The pyrolysis of the hydrocarbon product is preferably in a fluidised bed reactor wherein the fluidised bed comprises heat carrier particles comprising, or consisting, of zirconia, silica, alumina, or mixtures thereof. Optionally the heat carrier particles are regenerated heat carrier particles.

[0130] The heat carrier particles may be porous or non-porous. Preferred heat carrier particles have an average particle diameter size of 100-200 .m. Particle sizes are preferably measured by laser diffraction.

[0131] In preferred methods of the invention the weight ratio of heat carrier particles in the fluidised bed to hydrocarbon product feedstock is 40:1 to 3:1 , more preferably 30:1 to 5: 1 and still more preferably 20: 1 to 5: 1 . These ratios ensure that the pyrolysis reaction occurs quickly, and the residence time in the fluidised bed reactor can be minimised. Preferably the residence time of the hydrocarbon product in the fluidised bed reactor is 4-120 seconds, more preferably 5-30 seconds and still more preferably 5-10 seconds. The residence time in the fluidised bed reactor may be calculated by conventional techniques, e.g. as described by A. E. Ghaly and K. N. MacDonald, American Journal of Engineering and Applied Sciences, 2012, 5 (2), 170-183 based on the volume of the reactor and the gas flow rate. In preferred methods of the invention, the fluidised bed is continuously flushed with pre-heated inert gas, recycled gas, steam or mixtures thereof. Examples of suitable inert gas include nitrogen and CO2. Example of suitable recycled gas include noncondensables that are separated from the pyrolysis product. Preferably the inert gas has a temperature of 400-650 °C, more preferably 420-600 °C and still more preferably 450- 550 °C. Preferably the inert gas has a flow rate which enables the above-mentioned residence times to be achieved. The value of the flow rate is dependent on the volume of the reactor. However, the skilled person will readily be able to determine suitable flow rates.

[0132] In a preferred method of the present invention, pyrolysis to obtain pyrolysis product is carried out in a single step. Thus the overall method of the invention is fast and efficient. The total time from mixed polymer waste to pyrolysis product is preferably 1-20 minutes, preferably 2-12 minutes and more preferably 3-8 minutes.

[0133] The pyrolysis product is generally in the gas phase at the temperature of the fluidised bed. Generally the pyrolysis product is withdrawn from the top of the reactor. Optionally heat carrier particles or cooled heat carrier particles are withdrawn from the reactor, where they can be passed to a regenerator. Preferred methods of the invention comprise regenerating heat carrier particles. Regeneration can be carried out by conventional methodology. The regeneration step removes char, as well as inorganic contaminants (e.g. fillers, pigments) deriving from the polymer waste and / or degradation products thereof. In some methods and systems, it may be preferable to remove at least some of the inorganic material from the bed after pyrolysis. This may, for example, avoid the need for a melt filter after extrusion.

[0134] After pyrolysis, the pyrolysis product is preferably cooled. Thus a preferred method of the invention further comprises cooling to obtain pyrolysis product. Cooling may be carried out by any conventional means known in the art, e.g. in a heat exchanger, quencher etc.

[0135] Preferably the pyrolysis product is separated into non-condensable and condensable products. The non-condensable product may be, as mentioned above, fed into the fluidised bed reactor as part of the gas flow. Alternatively the non-condensable (gas) fraction is collected.

[0136] An advantage of the method of the present invention is that the yield of condensable products is at least 70 wt%, more preferably at least 80 wt% and yet more preferably at least 90 wt%, based on the total weight of pyrolysis product obtained. In other words, the vast majority of the pyrolysis product obtained may be potentially fed to a refinery unit.

[0137] In preferred methods of the invention the condensable products comprise at least 75 wt% C, more preferably at least 80 wt% C and still more preferably at least 84 wt% C, based on the total weight of the condensable products. The maximum may be 94 wt% C.

[0138] In further preferred methods of the invention the condensable products comprise at least 8 wt% H, more preferably at least 10 wt% H and still more preferably at least 12 wt% H, based on the total weight of the condensable products. The maximum may be 15.5 wt% H.

[0139] In further preferred methods of the invention the condensable products comprise less than 700 ppm N. In yet further preferred methods of the invention the condensable products comprise less than 600 ppm N, more preferably less than 300 ppm N and still more preferably less than 157 ppm N, based on the total weight of the condensable products.

[0140] In further preferred methods of the invention the condensable products comprise less than 3000 wt ppm O, more preferably less than 1000 ppm O and still more preferably less than 500 ppm O, based on the total weight of the condensable products.

[0141] In further preferred methods of the invention the condensable products comprise less than 100 ppm S, more preferably less than 20 ppm S and still more preferably less than 10 ppm S, based on the total weight of the condensable products.

[0142] In particularly preferred methods of the invention the condensable products comprise: at least 75 wt% C, more preferably at least 80 wt% C and still more preferably at least 83 wt% C; at least 8 wt% H, more preferably at least 10 wt% H and still more preferably at least 12 wt% H; less than 600 ppm N, more preferably less than 300 ppm N and still more preferably less than 157 ppm N; and less than 3000 wt ppm O, more preferably less than 1000 ppm O and still more preferably less than 500 ppm O, based on the total weight of the condensable products

[0143] In further preferred methods of the invention the condensable products have a bromine index of less than 50, more preferably less than 40 and still more preferably 0- 36. In further preferred methods of the invention, at least 90 wt% of the condensable products have a final boiling point of 40-700 °C, more preferably 70-680 °C and still more preferably 100-650 °C.

[0144] In further preferred methods of the invention, the condensable products comprise less than 10 wt%, more preferably less than 7 wt% and still more preferably less than 5 wt% aromatics. In yet further preferred methods of the invention, the condensable products comprise at least 20 wt% of paraffins, 40-70 wt% linear olefins and less than 10 wt% aromatics.

[0145] In preferred methods of the present invention the pyrolysis product, preferably the condensable pyrolysis products, is suitable for entry into the refinery value chain, e.g. waxes, oils and / or naphthas.

[0146] System

[0147] The present invention also relates to a system for producing a pyrolysis product from mixed polymer waste, preferably according to a method as hereinbefore described, comprising: an extruder for conversion of mixed polymer waste comprising 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, and chemicals, preferably alkali metal salt and / or alkali earth metal salt, into a mixture of hydrocarbon product and degradation products derived from the compounds, preferably polymer, comprising heteroatoms; optionally a melt filter for receiving the mixture of hydrocarbon product and degradation products from the extruder and removing solid degradation products from said hydrocarbon product; a degassing unit for receiving the hydrocarbon product from the extruder, or if present melt filter, and removing volatile degradation products from said hydrocarbon product; and a fluidised bed pyrolysis unit for receiving the hydrocarbon product from the extruder, or if present degassing unit, and pyrolysing said hydrocarbon product to obtain a pyrolysis product.

[0148] Another preferred system for producing a pyrolysis product from mixed polymer waste, preferably according to a method as hereinbefore described, comprises: an extruder for conversion of mixed polymer waste comprising 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, and chemicals, preferably alkali metal salt and / or alkali earth metal salt, into a mixture of hydrocarbon product and degradation products derived from the compounds, preferably polymer, comprising heteroatoms, wherein said extruder has a barrel comprising a devolatilization outlet for removing volatile degradation products; optionally a melt filter for receiving the mixture of hydrocarbon product and degradation products from the extruder and removing solid degradation products from said hydrocarbon product; and a fluidised bed pyrolysis unit for receiving the hydrocarbon product from the extruder, or if present degassing unit, and pyrolysing said hydrocarbon product to obtain a pyrolysis product.

[0149] Optionally, the above system also comprises a degassing unit for receiving the hydrocarbon product from the extruder, or if present melt filter, and removing volatile degradation products from said hydrocarbon product

[0150] A preferred system of the present invention comprises a melt filter. In preferred systems of the present invention comprising a melt filter, the outlet of the extruder from which the mixture of hydrocarbon product and degradation products is extruded is directly connected to the inlet of the melt filter. In further preferred systems of the present invention, the outlet of the melt filter unit is directly connected to the inlet of the degassing unit.

[0151] In another preferred system of the invention a melt filter is not required. In such systems, the outlet of the extruder from which the mixture of hydrocarbon product and degradation products is extruded is preferably directly connected to the inlet of the degassing unit.

[0152] Optionally the system comprises a mixing tank for mixing the mixed polymer waste and chemicals, preferably alkali metal salt and / or alkaline earth metal salt. Preferably the mixing tank is connected to the inlet of the extruder so the resulting mixture can be fed to the extruder. Alternatively, the mixing tank may be connected to an inlet of the extruder barrel so the chemicals may be added separately to the mixed polymer waste in the extruder. At least when an alkali metal salt and / or alkaline earth metal salt is employed, it is believed that some degradation of polymer comprising heteroatoms and / or non-polymeric compounds comprising heteroatoms may occur during this mixing. However, to achieve high levels of removal of polymer comprising heteroatoms and non- polymeric compounds comprising heteroatoms, it was found to be necessary to extrude the mixture according to the process hereinbefore described.

[0153] Optionally the system further comprises one or more holding tanks for storage of mixed polymer waste and chemicals. Optionally the system further comprises a pump and delivery device. The pump repressurizes and transports the hydrocarbon product, in the form of a melt, to a delivery device. Preferably the delivery device delivers or transports the hydrocarbon product into a fluidised bed pyrolysis unit.

[0154] Optionally the system further comprises a heating unit in between the degassing unit and the pump. This heating unit preferably heats the hydrocarbon product to 450- 500 °C, more preferably 350-420 °C prior to entry to the pyrolysis unit.

[0155] Optionally the system further comprises regenerator in fluid communication with the fluidised bed reactor. This enables heat carrier particles to be regenerated and returned to the reactor.

[0156] Preferably the system further comprises a first separator for receiving the pyrolysis product. Preferably the first separator has a temperature of 350-50 °C, more preferably 280-50 °C and still more preferably 150-80 °C. This first separator preferably collects the highest boiling point condensables.

[0157] Preferably the system further comprises a second separator for receiving pyrolysis product which is not separated out in said first separator. Preferably the second separator has a temperature of 200-50 °C, more preferably 150-50 °C and still more preferably 100-50 °C. The second separator preferably collects the condensables that are not collected in the first separator, e.g. middle boiling point condensables.

[0158] Preferably the system further comprises a third separator for receiving pyrolysis product which is not separated out in said first or second separators. Preferably the third separator has a temperature of +5 to -20 °C, more preferably 0 to -10 °C and still more preferably -5 to -10 °C. The third separator preferably collects the non-condensables.

[0159] Recycling mixed polymer waste

[0160] The present invention also relates to a method for recycling mixed polymer waste comprising a pre-treatment to remove compounds, e.g. polymer, comprising heteroatoms, comprising:

[0161] (i) feeding said mixed polymer waste into an extruder, preferably a single screw extruder;

[0162] (ii) adding chemicals, preferably alkali metal salt and / or alkali earth metal salt, to said mixed polymer waste to degrade said compounds, preferably polymer, comprising heteroatoms;

[0163] (iii) removing degradation products derived from said compounds, preferably polymer, comprising heteroatoms from said hydrocarbon product; and (iv) pyrolysing the hydrocarbon product in a fluidised bed reactor to obtain pyrolysis product.

[0164] Preferred features of the method hereinbefore described are also preferred features of the method for recycling mixed polymer waste.

[0165] The present invention also relates to a system for recycling mixed polymer waste, comprising: an extruder for conversion of mixed polymer waste comprising 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, and chemicals, preferably alkali metal salt and / or alkali earth metal salt, into a mixture of hydrocarbon product and degradation products derived from the compounds, preferably polymer, comprising heteroatoms; optionally a melt filter for receiving the mixture of hydrocarbon product and degradation products from the extruder and removing solid degradation products from said hydrocarbon product; a degassing unit for receiving the hydrocarbon product from the extruder, or if present melt filter, and removing volatile degradation products from said hydrocarbon product; and a fluidised bed pyrolysis unit for receiving the hydrocarbon product from the extruder, or if present the degassing unit, and pyrolysing said hydrocarbon product to obtain a pyrolysis product.

[0166] Another system for recycling mixed polymer waste, comprises: an extruder for conversion of mixed polymer waste comprising 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, and chemicals, preferably alkali metal salt and / or alkali earth metal salt, into a mixture of hydrocarbon product and degradation products derived from the compounds, preferably polymer, comprising heteroatoms, wherein said extruder has a barrel comprising a devolatilization outlet for removing volatile degradation products; optionally a melt filter for receiving the mixture of hydrocarbon product and degradation products from the extruder and removing solid degradation products from said hydrocarbon product; and a fluidised bed pyrolysis unit for receiving the hydrocarbon product from the extruder, or if present degassing unit, and pyrolysing said hydrocarbon product to obtain a pyrolysis product.

[0167] The invention will now be described using the following non-limiting examples and Figures, wherein: Figure 1 is a block diagram of a preferred system of the present invention, wherein an extruder, a melt filter, and a degassing unit are each connected in series. The mixed polymer waste and chemicals, preferably alkali metal salt and / or alkaline earth metal salt, are fed into the extruder, and solid degradation products from heteroatom-containing polymer and / or non-polymeric heteroatom-containing compounds are removed from the hydrocarbon product in the melt filter and volatile degradation products are removed in the degassing unit. The resulting hydrocarbon product, which is cracked polyolefin, has a lower molecular weight, lower viscosity and higher MFR2 than the mixed polymer waste starting material. It is much more suitable as a feedstock for a pyrolysis unit because it has a much lower content of heteroatom containing compounds. The hydrocarbon product is pumped to a delivery device from which it is added into a pyrolysis unit.

[0168] Figure 2 shows the MFR2 of virgin LLDPE, LDPE and PP after extrusion. Virgin grade non-extruded references are close to MFR2 ~1 for PE, and MFR2 - 3 for PP;

[0169] Figure 3 shows the average MW (GPC) of virgin LLDPE, LDPE and PP after extrusion as well as virgin grade non-extruded references;

[0170] Figure 4 shows the complex viscosity (Pa*s) at 0.5 and 200 rad / sec for LLDPE and PP after extrusion in the range 300-380 °C and 20-60 RPM, as well as non-extruded virgin references;

[0171] Figure 5 shows the remaining PET and PA-6 (wt%) in samples deriving from feedstock containing 10-30 wt% PET and PA-6, extruded at 370 °C and 20 RPM, in alkaline conditons;

[0172] Figure 6 shows the MFR2 of PET and PA-6 in 10-30 wt% PA / PET / PE samples extruded at 370 °C and 20 RPM in alkaline conditions;

[0173] Figure 7 shows the remaining PET and PA-6 (wt%) in samples deriving from feedstock containing 5 wt% PET and PA-6, extruded at 350 and 370 °C and 20-200 RPM, in alkaline conditions;

[0174] Figure 8 shows the MFR2 in 5 wt% PET / PE or PA-6 / PE extruded in the temperature range 350-380°C and 20-200 RPM in alkaline conditions;

[0175] Figure 9 shows the remaining PET and PA-6 (wt%) in samples derving from feedstock containing 10 wt% PET and PA-6, extruded at temperatures in the range 350- 380 °C and at 20-60 RPM, in alkaline conditions;

[0176] Figure 10 shows the MFR2 in 5 wt% PA-6 / 5 wt% PET in LLDPE blends extruded in the range 350-380 °C and 20-60 RPM, in alkaline conditions; Figure 11 shows the remaining PA-6 left (wt%) in samples deriving from PA-6 / PE feedstock extruded in the temperature range 350-380 °C and 20-60 RPM in alkaline conditions;

[0177] Figure 12 shows the MFR2 of PA-6 / PE extruded in the temperature range 350- 380 °C and 20-60 RPM in alkaline conditions;

[0178] Figure 13 shows the PA-6 left (wt%) in PE / PA-6 samples deriving from multilayer films extruded in the temperature range 350-370 °C and 20-100 RPM in alkaline conditions;

[0179] Figure 14 shows MFR2 of PE / PA-6 deriving from multilayer films extruded in the temperature range 350-370 °C and 20-100 RPM in alkaline conditions;

[0180] Figure 15 shows complex viscosity (Pa*s) for extruded PET / PE, PA-6 / PE and PA-6 / PET / PE in alkaline conditions against a baseline 5 wt% PET / PE extruded and virgin LLDPE included as a reference;

[0181] Figure 16 shows the remaining PET (wt%) in samples deriving from 5 wt% PET / PE model waste after extrusion in a twin screw extruder under different conditions.

[0182] Figure 17 shows the yield of condensed and non-condensed products for pyrolysis of LLDPE in a fluidized bed reactor, at temperatures of 440 °C and 500 °C, nitrogen flow rates 50 NL / min and 110 L / min and bed material 4 kg and 7 kg;

[0183] Figure 18 shows the pyrolysis product yield for LLDPE, LDPE and LDPE:PP at 450°C and 50 NL / min nitrogen flow rate;

[0184] Figure 19 shows the boiling point distribution of the pyrolysis product obtained from examples 11 and 13;

[0185] Figure 20 shows the PIONA analysis (wt% of paraffins, iso-paraffins, olefins, naphthenes and aromatics) of the pyrolysis product obtained from examples 11 and 13;

[0186] Figure 21 shows the analyses results on PA-6 / LDPE after extrusion with NaOH (pretreated) and without NaOH (untreated);

[0187] Figure 22 shows the shows the product yield of condensables and noncondensables for the pyrolysis of LDPE, pretreated (5% and 10 %) PA-6 / LDPE and untreated 5% PA-6 / LDPE;

[0188] Figure 23 shows the boiling point distribution of the pyrolysis product obtained from LDPE, and pretreated 5% PA-6 / LDPE;

[0189] Figure 24 shows the PIONA analysis (wt% of paraffins, iso-paraffins, olefins, naphthenes and aromatics) of the pyrolysis product obtained from LDPE, untreated 5% PA-6 / LDPE and pretreated 5% PA-6 / LDPE and 10 % PA-6 / LDPE; Figure 25 shows the nitrogen content of treated PA-6 / PE (5% and 10 % PA-6), after the extruder process and after pyrolysis;

[0190] Figure 26 shows the gas composition (hydrocarbons and non-hydrocarbons) for the pyrolysis of untreated 5% PET / LLDPE and pretreated 5% PET / LLDPE;

[0191] Figure 27 shows the FTIR spectrum of the solid collected from condensed liquid product from Example 23, compared to a reference spectrum of benzoic acid;

[0192] Figure 28 shows the product distribution in terms of carbon numbers above C6 and below C5 obtained from treatment of real waste samples, MPW-1C, MPW-2C and MPW-3C in Examples 27, 30 and 31 ;

[0193] Figure 29 shows the boiling point distribution of the product produced by combining vessels 2 and 3 of the pyrolysis product obtained from MPW-1C and MPW- 2C in Examples 27 and 30 respectively; and

[0194] Figure 30 shows the PIONA analysis (wt% of paraffins, iso-paraffins, olefins, napthenes and aromatics) of the pyrolysis product obtained from MPW-2C and MPW- 3C in Examples 30 and 31.

[0195] EXAMPLES

[0196] Materials

[0197] The following materials listed in Table 1 were prepared and mixed to simulate post-consumer waste (PCW) comprising PET and PA-6 from multilayer film packaging.

[0198] As a reference, a PA-6 / PE multilayer film with 34 wt% PA-6 was included in some experiments, marked “MF”. The film was shredded and diluted with LLDPE to reach 5% PA-6 in the feed.

[0199] Table 1

[0200] Analysis methods

[0201] FTIR analysis

[0202] Sample preparation for FTIR analysis:

[0203] The samples were prepared for analysis by cutting and milling the samples to granulates approximately 5-10 mm size. They were dried in a vacuum oven at 80 °C for 8 hours at 0.8 Bar. The sample granulates were hot pressed to films of 0.1 mm thickness with a hot press (M-4411 Collin 200P hydraulic press) using a copper mould with Teflon sheets. At least 2 parallels were pressed of each sample.

[0204] Hot press program:

[0205] - 30 sec. at 15 bar

[0206] - 10 sec. at 30 bar

[0207] - 10 sec. at 70 bar

[0208] - 40 sec. at 250 bar

[0209] - 300 sec. at 250 bar (cooling)

[0210] Data acquisition'.

[0211] - FTIR spectra were recorded in transmission mode with film holder using a Perkin-Elmer Spectrum TWO equipped with a LiTaOs detector and Spectrum 10 software.

[0212] - The spectral range was 450-4700 cm-1and 12-16 scans were recorded per spectrum with a scan resolution 4 cm-1.

[0213] - For quantification of PA-6 or PET in the PE samples, the software Perkin- Elmer SpectrumQuant, version 10.6.0.893 was used.

[0214] - PLS method with Principal Component Analysis (PCA) was used for quantification. Standard error of estimate (SEE) for each component; 0.4 wt% for PE, 0.2-0.4 wt% for PA-6 and 0.3 wt% for PET.

[0215] - Parallels with more than 0.5% deviation were investigated further using up to 5 parallels.

[0216] - The calibration model was established using relevant compounded PE / PA- 6. PE / PET and PE / PA-6 / PET reference blends. The calibration samples were milled and compounded using the same polymer grades as in the model waste feedstock to ensure homogeneity.

[0217] Melt Flow Rate (MFR)

[0218] The MFR2 of the extruded granulated melt was measured according to NS-EN ISO1133-1 :2011 using a Davenport Melt Flow Indexer, Model 3. The conditions used were: 2.16 kg load; die diameter 0.5 mm; die length 8 mm. The MFR unit is g / 10 min at 2.16 kg. The measurement is conducted at 190 °C (PE) and 230 °C (PP) and the pre-heating was 5 minutes. Two parallels were used.

[0219] Maximum measurable value is 600-700 g / 10 min at 2.16 kg load (ca. 20 in standard deviation).

[0220] GPC

[0221] Gel Permeation Chromatography was carried out according to ISO16014-1 , -2, -4, 2012 using a GPC-IR5 MCT from Polymer Char equipped with an IR5 MCT Infrared detector. The polymer samples were dissolved in trichlorobenzene (TCB) at 160 °C for 1-4 hours (0.25-1.8 mg / mL). The columns 1 PL gel Guard and 4 PL gel 20 pm MIXED-A were heated to 150 °C. Two parallels were used.

[0222] GPC was used for determination of:

[0223] Mw- Mass average molecular mass

[0224] Mn- Number average molecular mass

[0225] Mw / Mn- Polydispersity of the sample Complex viscosity measurements

[0226] Complex viscosity, q*, is a measure of the total resistance to flow as a function of angular frequency, q* was measured according to 1506721-10:2015 using an RDA II W-4408 instrument. The samples were compression moulded into plates with dimensions 1.5 mm thickness and 30 mm diameter. The preheat time was 200 s to reach 300 °C. The test conditions were 300 °C; frequency range 0.1-300 rad / sec; scraping off gap 1.25 mm; measuring gap 1.20 mm; plate geometry Plate-Plate; plate diameter 25 mm.

[0227] The method is used to determine values of the following dynamic rheological properties:

[0228] W: Angular velocity, rad / sec

[0229] G’: Storage modulus

[0230] G”: Loss modulus

[0231] Complex modulus G*=(G’2+ G”2)1

[0232] Complex Viscosity Eta=G* / w

[0233] Where eta(0. 5): Complex viscosity at frequency 0. 5 rad / sec and eta(200): Complex viscosity at frequency 200 rad / sec are reported herein.

[0234] Liquid chromatography, HPLC-UV

[0235] Method Liquid chromatography according to according to Norner internal method M730533

[0236] Definitions HPLC is a chromatographic technique that separates components in a mixture by use of liquid. The technique is used for both qualitative and quantitative analyses.

[0237] Instrument Agilent 1200

[0238] Specimen type Polymer sample milled to powder before extraction

[0239] Test conditions 1. Sample preparation: Extraction

[0240] 2. Chromatographic conditions:

[0241] Column: C-18

[0242] Mobile phase: Water / AcN / IPA-gradient

[0243] Detector: UV, 276 nm

[0244] Gas chromatography with Mass Spectrometric detector, GC- MS

[0245] Method Gas Chromatography with MS detector according to Norner internal method M730544 Definitions The GC separates the chemical mixture, and the MS identifies and quantifies the chemicals based on their structure

[0246] Instrument Agilent 6890

[0247] Specimen type Polymer sample milled to powder before extraction

[0248] Test conditions Sample preparation: Extraction

[0249] Chromatographic conditions:

[0250] Column: HP-5

[0251] Carrier gas: Helium

[0252] Detector: Mass Spectrometric, MS

[0253] Inline Gas Chromatography

[0254] Refinery Gas Chromatography (RGA)

[0255] Method Gas Chromatography ASTM D1946

[0256] Definitions The Refinery gas Analyser is a multi-channel analyzer equipped with two Flame Ionization Detectors (FID) and one Thermal Conductivity Detector (TCD) and a valvebox option.

[0257] Instrument Agilent 7890

[0258] Specimen type Hydrocarbon and non-hydrocarbon gas sample

[0259] Test conditions Sample preparation: Inline sample analysis

[0260] Chromatographic conditions:

[0261] Column: Proprietary capillary and Micropacked columns Carrier gas: Helium

[0262] Detector: Flame Ionisation Detector (FID) and Thermal Conductivity Detector (TCD).

[0263] Analysis time was 20 minutes. Three parallels were used, averaged and normalized.

[0264] Detailed hydrocarbon analyzer (DHA)

[0265] Method Gas Chromatography ASTM D6729

[0266] Definitions The Detailed Hydrocarbon Analyser consists of a split injection system with a long capillary column. Detection of the components is performed with a Flame Ionization Detector (FID).

[0267] Instrument Agilent 7890

[0268] Specimen type Hydrocarbon liquid sample

[0269] Test conditions Sample preparation: Filtered to remove any solid particles Chromatographic conditions: Column: 100 meter 0,32 ID

[0270] Carrier gas: Helium and hydrogen

[0271] Detector: Flame Ionization Detector (FID).

[0272] DHA analysis was conducted in offline mode. The samples were injected using an auto sampler and the analysis time was 180 minutes.

[0273] Bromine index

[0274] Bromine index was measured by using the standard test method ASTMD2710-20. This test method provides a measure of trace amounts of unsaturated hydrocarbons in petroleum distillates boiling up to 288 °C (550 °F).

[0275] Ash content and elemental composition by Energy Dispersive Spectroscopy

[0276] The sample material was weighed, and placed in a crucible for ashing. The ashing was conducted in a Nabertherm furnace oven at 650 °C for 1 hour according to ISO 3451-1 . The ash residue of the sample was weighed and the ash content was calculated. The ash was analysed using SEM-EDS (Hitachi Sil-5000 with Bruker Quantax 800 EDS). The acceleration potential was 15 kV, using a low vacuum mode. The inorganic elements were identified and quantified using a Back-scattered electron detector. The identified inorganic elements were calculated as a concentration of elements in the polymer material.

[0277] Extrusion testing

[0278] Sample preparation

[0279] Virgin LLDPE (Q1018N, Total) was mixed with pure extrusion grade PA-6 (B40LN, BASF, 5-15 wt%) and / or PET (RAMA-PET N180, 5-15 wt%) to simulate typical and extreme PCW compositions. Sodium hydroxide (NaOH, Sigma-Aldrich) and / or calcium hydroxide (Ca(OH)2, Sigma-Aldrich) was dissolved in distilled water (5-12 wt%) and stirred into the polymer blends in various concentrations (0.5-2 wt%). The homogeneous blends were extruded immediately after preparation.

[0280] Samples comprising LDPE and / or PP were prepared in an analogous manner. Extrusion

[0281] Unless otherwise stated, the materials were extruded in a GA25-25D single screw extruder in the temperature range 350 to 380 °C. The RPM range was 20 to 200 revolutions per minute (RPM), corresponding to a residence time of 4.0-4.7 minutes to 0.5-0.8 minutes, respectively (see Table 2 below). The conversion of RPM to residence time was measured by determining the amount of time it takes for a sample to pass through the extruder at different RPM levels. The extrudate samples were collected at stable operating conditions and were cooled to room temperature for analysis.

[0282] Table 2: Conversion of RPM to minutes

[0283] A number of experiments were also conducted to compare the performance of the above-mentioned GA25-25D extruder, with a screw designed for optimal venting out of the extruder die, to screw designed for optimal mixing. Both arrangements employed the same extruder, but with different screws. The second arrangement, herein referred to as “screw 2” is the GA-25D extruder with a mixing screw in place. It has a D of 25 mm and several mixing elements.

[0284] During extrusion, the degradation products that are volatiles (e.g. CO2, H2O, ethylene glycol, low MW hydrocarbons) are removed through the extruder (there is a slight vacuum at the end of the extruder). The salts formed (e.g. sodium / calcium benzoate, sodium / calcium terephthalate, sodium / calcium carbonate) were extruded with the homogeneous blend and subsequently removed from the blend in a melt filter.

[0285] Results

[0286] Example 1a: Degradation of virgin PE and PP

[0287] Selected pure virgin grades, LLDPE, LDPE and PP, were extruded in a GA25- 25D single screw extruder at 300, 350, 370 and 380 °C using 20 or 60 revolutions per minute (RPM), corresponding to a residence time of approximately 1.4-1.8 and 4.0-4.7 minutes. The extrudate samples were collected after obtaining steady state conditions and cooled in room temperature. (800 g / 10 min at 2.16 kg is set as value whenever the melt flow rate is too high for correct measurement (normally over 700). MFR2 was used to measure the viscosity of the melt after extrusion. Each of LLDPE and PP was investigated more closely with dynamic rheology to measure complex viscosity at different shear rates at 300 °C. The polymer molecular weight and distribution were analysed by GPC. The results are shown in Table 3 and in Figures 2-4.

[0288] *800 is given as the value for MFR2 when the MFR is too high for accurate measurement under standard conditions.

[0289] Table 3

[0290] Figure 2 shows the MFR2 for LDPE, LLDPE and PP before and after extrusion. The melt flow rate increases abruptly between 370 and 380 °C and from 60 RPM to 20 RPM. PP is more easily degraded compared to PE.

[0291] Figure 3 shows the average molecular weight from GPC for PP, LDPE and LLDPE. The degree of cracking is significant at 350, 370 and 380 °C. 20 RPM results in more pre-cracking.

[0292] Figure 4 shows the complex viscosity measured for LLDPE and PP before and after extrusion. Corresponding to MFR2 and MW, the PP and LLDPE grades exhibit significantly lower viscosity at higher temperatures and lower RPM.

[0293] Comparison of the results for LLDPE with the standard screw and screw 2 show that employing a screw designed for mixing reduces the molecular weight and viscosity to higher levels. The MFR2 was, in fact, too high to measure.

[0294] HDPE was also degraded similarly to LLDPE and LDPE.

[0295] This experiment demonstrates the baseline degradation, referred to as precracking, of virgin LDPE, LLDPE and PP upon extrusion in the range 300-380 °C and 20-60 RPM. Example 1 b: Analysis of Additives in extruded PP, LLDPE, and HDPE

[0296] Table 4 below lists common additives present in PE and PP typically used for packaging. These additives, and their degradation products, are well known and can be identified by HPLC, GC-MS and GC-FID.

[0297] Table 4

[0298] Table 5 below lists the additives that were identified in the PP, LLDPE and HDPE grades employed before and after extrusion (LDPE was not included because it did not contain any additives). Extrusion was carried out at 380 °C and 20 RPM, with or without alkaline solution. The effect of pre-mixing the polymer with an alkaline solution (1 wt% NaOH, 1 wt% Ca(OH)2, 5 wt% H2O) was studied. The additives and their degradation products were detected by HPLC and GC-MS as described above. ND means not detected.

[0299] Table 5 - Total AO-168 is AO-168 + oxidised AO-'

[0300] The results show that the process of the invention effectively degrades the heteroatom containing additives commonly present in PP, LLDPE and HDPE. Specifically, in PP and HDPE Arvin 2 and Arvin 4, which are the hydrolysis products of AO-168 were detected. Residual AO-168, A-1010 and A-1076 were not detected in polymers, which underwent extrusion in the presence of alkaline solution.

[0301] Example 2: Removal of 10-30 % PET / PA-6 from PE blends

[0302] Virgin LLDPE (Q1018N, Total) was mixed with pure extrusion grade PA-6 (B40LN, BASF, 5-15 wt%) and PET (RAMA-PET N180, 5-15 wt%) to simulate PCW compositions. Three sample compositions were prepared: 1) 5% PA-6 and 5% PET in PE; 2) 10% of PET and 10 % PA-6 in PE, and; 3) 15% PA-6 and 15% PET in PE. Sodium hydroxide (NaOH, Sigma-Aldrich) and calcium hydroxide (Ca(OH)2, Sigma-Aldrich) was added to the 3 samples: 1) 1.5 % NaOH and 1% Ca(OH)2; 2) 3 wt% NaOH + 2% Ca(OH)2, and 3) 4.5% NaOH + 3% Ca(OH)2. Distilled water was added to the mixture and kept constant at 12 wt%. The homogeneous blends were extruded immediately after preparation in a GA25-25D single screw extruder at 370 °C and 20 revolutions per minute (RPM), corresponding to a residence time of approximately 4.0-4.7 minutes. The extrudate samples were collected after obtaining steady state conditions and cooled in room temperature. The volatised side products exiting the extruder with the polymer melt were vented out, and hence separated from the polymer. The samples were prepared for analysis as described above. FTIR spectra were recorded using the acquisition method, and then analysed, as described above. MFR2 was measured at standard conditions (190 °C) using 0.5 mm die as described above. Selected samples were investigated more closely with dynamic rheology to measure complex viscosity at different shear rates at 300 °C. The results are shown in Table 6 below and in Figures 5 and 6.

[0303] Table 6

[0304] The results demonstrate the efficient, concurrent, removal of PA-6 and PET from feedstock comprising 5%, 10% and 15 wt% of both PET and PA-6 in LLDPE (i.e. up to 30 %wt compounds containing heteroatoms). Specifically, the results show 68-87 % concurrent removal of PA-6 and PET from feed containing up to 30 wt% heteroatomcontaining polymer after extrusion at 370 °C and 20 RPM in aqueous alkaline conditions. This test feedstock contains significantly more heteroatom-containing polymers that conventional PCW feedstock. It is surprising that the process is able to remove so much PET and PA-6, even from feedstock containing a total of 30 wt% PET and PA-6. The result for the feedstock comprising 15 wt% PET and PA-6 shows that the hydrocarbon product emerging from the extruder contains 1.9 wt% PET and 2.4 wt% PA-6, which is less than the amount of PET and PA-6 typically present in PCW that can be recycled. Thus the process provides a highly efficient method to remove heteroatom-containing polymers from highly contaminated PCW prior to further processing to achieve recycling.

[0305] The MFR2 results indicate that the viscosities of the hydrocarbon product produced in the process is higher than, or comparable to baseline degradation of LLDPE (-111 vs. 100) at these conditions.

[0306] Example 3: Effect of RPM

[0307] The sample preparation and analysis procedure were as described above and in Experiment 1 . The experiments were carried out at temperatures in the range 350 - 370 °C, and at 20 -200 RPM, using the recipes and conditions set out in Table 6. The results are shown in Table 7, and Figures 7 and 8.

[0308] Table 7

[0309] The results show that the PET and PA-6 are degraded and removed during extrusion wherein the mixed polymer waste has a residence time in the extruder between 0.5-4.7 min. The removal of PET and PA-6 in PE is significantly more efficient at 20 RPM (residence time 4.0-4.7 min) than at 200 RPM (residence time 0.5 - 0.8 min) and 100 RPM (residence time 1.0-1.2 min). This is consistently the case regardless of the PET / PA-6 content, the alkaline mix and the water content. Whilst alkaline hydrolysis of PA-6 appears to be slower than for PET, both PA-6 and PET can be concurrently removed from PCW. MFR2 increases with decreasing RPM, but is affected by the wt% PET and PA-6 present when compared to baseline LLDPE degradation.

[0310] This experiment also included some multilayer film (MF) to compare the results for a real film versus the feedstock specifically prepared for development purposes. The results appear to be comparable.

[0311] Example 4: Process window for efficient concurrent removal of PET and PA-6

[0312] The sample preparation and analysis procedure were as described above and in Experiment 1. The experiments were carried out at temperatures of 350, 370 and 380 °C using 60 and 20 revolutions per minute (RPM), corresponding to a residence time of 1.4-1 .8 minutes and 4.0-4.7 minutes respectively, using the recipes and conditions set out in Table 8. The results are shown in Table 8 and in Figures 9 and 10.

[0313] Table 8

[0314] The results show that concurrent removal of mixed PA-6 and PET is efficient at

[0315] 20 RPM in the temperature 350-380 °C range. MFR2 is significantly lower at 60 RPM vs. 20 RPM.

[0316] Example 5: Process window for PA-6 removal

[0317] The sample preparation and analysis procedure were as described above and in Experiment 1. The experiments were carried out using the recipes and conditions set out in Table 9. In this experiment model waste is represented both as blended PA-6 and LLDPE pellets and multilayer film (MF) flakes for comparison with a more realistic feed. The results are shown in Table 9 and in Figures 11 and 12 for the PA-6 / PE blends and in Table 10 and Figures 13 and 14 for the multilayer film.

[0318] Table 9

[0319] Table 10

[0320] Corresponding to examples 2 and 3, the results indicate that PA-6 is removed more efficiently at 20 RPM vs. 60 RPM in the range 350-380 °C. Small variations are observed across the chemical recipes and temperature range. The results suggest that residence time (RPM) is the most significant factor in determining the efficiency of PA-6 removal. Example 6: Effect of water

[0321] The sample preparation and analysis procedure were as described above and in Experiment 1. The experiments were carried out using the recipes and conditions set out in Tables 11.1 and 11.2. Tables 11.1 and 11.2 also show the results achieved.

[0322] Table 11.1

[0323] Table 11.2

[0324] The results in these tables show that, under the conditions used in this example,

[0325] PET is more efficiently removed using a higher amount of (e.g. 8 %) water as opposed to a lower amount (e.g. 5 %) water. This suggests that in this example aqueous hydrolysis is generally preferable.

[0326] Without wishing to be bound by theory, it is thought that using higher %wts of water promotes hydrolytic degradation over thermal degradation. The water may be added or may be present in the mixed polymer waste fed to the extruder. Hydrolytic degradation is desirable because it gives rise to degradation products that can be removed from the extrudate. Moreover, at least some of the degradation products are in the form of monomers that can be recovered and recycled.

[0327] Example 7: Complex viscosity for purified PET / PE, PA-6 / PE and PA-6 / PET / PE blends

[0328] Some purified extrudates were selected for complex viscosity measurements. The following data provide further insight in viscosity of a relevant product stream vs. the reference degradation.

[0329] Table 12 lists complex viscosities measured at 0.5 and 200 rad / s of selected samples from experiment 1-5; PET / PE, PA-6 / PE and one PET / PA-6 / PE. Figure 15 shows a complex viscosity crossplot at 0.5 and 200 rad / s, compared to virgin LLDPE and baseline extruded PET / PE.

[0330] Table 12 The results demonstrate that the complex viscosity of the extruded hydrocarbon product is in the range of the reference degradation of LLDPE in the process window 350-380 °C and 20-60 RPM.

[0331] Example 8 - Analysis of Volatile Degradation products

[0332] The sample preparation was conducted as described in Experiment 1 and is summarised in Table 13 below. The homogeneous blends were extruded immediately after preparation in a GA25-25D single screw extruder at 380°C and 20 revolutions per minute (RPM), corresponding to a residence time of approximately 3.5-4 minutes. The polymer melt samples was collected after obtaining steady state conditions and cooled in room temperature.

[0333] Two extrusion trials with a duration of 4-5-hours were conducted with 2 different water compositions to collect enough of the condensable side product for analyses. The degradation product was separated from the polymer stream in a buffer tank (“hopper tank”) as a volatile product in, immediately after being collected from the extruder using a slight vacuum. The volatile product exiting the extruder die and polymer melt was condensed and collected during extrusion. Some of the product was condensed in the condenser, rather than in the round flask further downstream, indicating higher boiling point. This was also collected and analysed separately (sample PA-6 / 26). The condensable products were analysed by HPLC, which was calibrated for specific substances expected from PA-6, PA-6.6 and PET. The results are summarised in Table 13 below.

[0334] Table 13

[0335] Example 9 - Analysis of salts produced by degradation

[0336] The sample preparation was conducted as described in Experiment 1 as summarised in Table 14 below. Two extrusion trials were conducted with different compositions of the chemical package. The homogeneous blends were extruded immediately after preparation in a GA25-25D single screw extruder at 350°C and 20 and 60 revolutions per minute (RPM). The extrudate samples were collected after obtaining steady state conditions and cooled at room temperature.

[0337] HPLC measurements were carried out to identify compounds in the polymer melt after extrusion of 5% PET in LLDPE model waste with NaOH and NaOH / Ca(OH)2 / H2O. The method identifies sodium or calcium benzoate or terephthalate. (The method cannot distinguish between terephthalate and benzoate, or whether the associated cation is sodium or calcium).

[0338] Table 14

[0339] Sodium and / or calcium benzoate / terephthalate side products were identified by HPLC analysis in the extruded PE / PET material. These are the expected products from alkaline hydrolysis of PET. PET-4 contained 60 ppm sodium benzoate / terephthalate. PET-7 contained 40 ppm of sodium and / or calcium benzoate / terephthalate. (Due to overlapping peaks in the chromatogram, the contribution from the individual substances could not be determined).

[0340] Example 10: Use of a twin screw extruder

[0341] This example demonstrates that the method can be carried out in a twin screw extruder. It is beneficial due to its mixing abilities for incompatible elements in the feed.

[0342] The sample preparation of 5% PET / PE and chemicals was carried out by the method explained for example 1. The feed rate of the model waste to the extruder was 1 kg / h using a hopper with a screw feeder. The twin screw extruder was set to its minimum 120 RPM which corresponds to 50 sec residence time. This is the lowest RPM possible. The feedstock was extruded at 370 °C and 380 °C.

[0343] The twin screw extruder has screw diameter of 18 mm and l / d = 60 and operates in co-rotating configuration.

[0344] Table 15 and Figure 16 show the PET remaining in the polymer melt after extrusion with pre-mixed dry alkali hydroxides or NaOH and Ca(OH)2 or as an aqueous solution, using various amounts of water. One reference trial with extrusion of the 5% PET / PE feedstock without the chemicals show that thermal degradation is significant under these conditions. The optimal point according to this data set and conditions is when NaOH, Ca(OH)2 and water was added in stoichiometric amounts (0.5% water).

[0345] Table 15

[0346] Extrusion and Pyrolysis testing

[0347] Sample preparation

[0348] Compounding: Virgin LDPE (FT5230, Borealis) was mixed with 5-10 wt% pure extrusion grade PA-6 (B40LN, BASF) to simulate typical PCW compositions. The mixture was compounded in a Coperion ZSK26 twin screw extruder to yield pellets or granulates. Conditions for the compounding are given in Table 16 below.

[0349] Extrusion: Compositions comprising PA were extruded in a ZSK18 twin screw extruder at 380 °C. The RPM was 120 revolutions per minute (RPM). The extrudate samples were collected at stable operating conditions, the melt string was cooled in a water bath, pelletized and dried at 100 °C for analysis and subsequent feeding to the pyrolysis process. During extrusion, volatile degradation products (e.g. CO2, H2O, low molecular weight hydrocarbons, nitrogen and oxygen containing compounds) were removed through the extruder via a slight vacuum at its end.

[0350] Table 16

[0351] General procedure for Pyrolysis

[0352] The selected feedstock, prepared as described above, was added to a Coperion K-tron gravimetric feeder and was therefrom fed, via a screw, to a GA-25-25D single screw extruder at 380 C. The feeder adjusts the feed rate using a balance. The extruder process conditions are described in Table 17 below.

[0353] The extruded polymer melt was fed to a fluidised bed reactor with a set point of 450-600 °C. The temperature in the reactor (i.e. the fluidised bed temperature) was monitored. The pressure in the fluidised bed was not set, but was typically in the range 0.5-0.7 bar. The pressure inside the reactor was monitored.

[0354] The reactor contained a fluidized bed of heat carrier particles and was continuously flushed with pre-heated nitrogen to maintain fluidization. A cyclone and a hot particle filter were mounted after the outlet of the fluidised bed reactor.

[0355] After reaching steady state, evidenced by stable temperature and pressure, the gaseous pyrolysis product exiting the fluidised bed reactor was cooled and collected in three different gas / liquid separators, each maintained at different temperatures. Noncondensable gases were monitored in a gas totalizer and analysed by in-line GC-RGA for chemical composition analysis. The condensed products from the Gas / Liquid separators were transferred to product storage vessels. The yield of collected pyrolysis products was gravimetrically determined.

[0356] Table 17

[0357] Results Examples 11-13

[0358] Example 11 :

[0359] LLDPE virgin polymer was added to a Coperion K-tron gravimetric feeder to feed 1 kg / h to a GA25-25D single screw extruder. The extruder operated at 380 °C using 12.7 RPM, corresponding to an approximate residence time of 2-4 minutes. The extruded polymer melt was continuously fed to the fluidised bed reactor via a conduit from the extruder die at 370 °C. The reactor temperature was 440 and 500 °C, the amount of heat transfer particles was 4 kg, 5.5 kg and 7 kg, respectively, and the nitrogen flow rate was varied at 25, 50 and 110 NL / min. The residence times in the fluidised bed reactor were 31 , 15 and 7 seconds, respectively. These residence times were calculated, according to conventional methodology, based on the extruder volume and flow rate. After reaching steady state the samples were collected in three gas / liquid separators maintained at the temperatures as shown in Table 17 above. Example 12:

[0360] For the LDPE virgin polymer, the experiment was carried out as described in Example 11, using 5.5 kg zirconia as bed material and a nitrogen flow of 50 NL / min and a temperature of 450°C in the fluidized bed reactor.

[0361] Example 13:

[0362] For the LDPE / PP virgin polymer blend, the experiment was carried out as described in Example 11 , using 5.5 kg zirconia and a nitrogen flow of 50 NL / min and a temperature of 450°C in the fluidized bed reactors. The results are shown in Table 18 and in Figures 17-18. The extruder pressure remained at 0-1 Barg in all experiments. The fluidized bed reactor pressure varied from 0.7 Bar (25-50 NL / min) to 1.7 Bar (110 NL / min). The results showed that the preferred conditions were 5.5 kg and a nitrogen flow of 50 NL / min. The results show that a high flow rate of 110 NL / min resulted in an undesired pressure increase in the reactor.

[0363] 1 ) Calculated residence time based on reactor length and gas velocity, 2) The transfer line after the reactor before the hot filter, 3) The transfer line after g / l separator 1 , before g / l separator 2.

[0364] Table 18 Figure 19 shows the boiling point distribution of the pyrolysis product obtained from vessel 1 for examples 11 and 13. The results show that the boiling point distribution is almost identical for both samples, irrespective of the presence of PA in one feedstock.

[0365] Figure 20 shows the PIONA analysis (wt% of paraffins, iso-paraffins, olefins, naphthenes and aromatics) of the pyrolysis product obtained from examples 11 and 13. The results show that the chemical composition is very similar for both samples, irrespective of the presence of PA in one feedstock.

[0366] These results show the effectiveness of the combined extrusion and pyrolysis process in removing PA from the feedstock.

[0367] Examples 14-17

[0368] Example 14:

[0369] A PA-6 / LDPE blend containing 5 wt % PA-6 was prepared by compounding PA- 6 (Ultramid B40LN, BASF) and LDPE (FT5230, Borealis) in a Coperion ZSK26 twin screw extruder at 230 °C and 500 RPM. The blend was collected as pellets and dried.

[0370] Example 15:

[0371] A PA-6 / LDPE blend containing 5 wt % PA-6 was prepared as described in Example 14. The compounded material was premixed with dry sodium hydroxide pellets (NaOH, Sigma-Aldrich) in a molar ratio PA-6:NaOH = 2, and subsequently added to a Coperion K-tron gravimetric feeder connected to a Coperion ZSK18 twin screw extruder operated at 380 °C and 120 RPM, corresponding to a residence time of approximately 50 seconds. The feed rate into the extruder was gradually increased from 3.5 kg / h to 4 kg / h to ensure stable operation. The extruder barrel was equipped with a devolatilization outlet close to the extruder die. A slight vacuum was used to encourage the volatiles to be removed from the polymer melt and vented. The extruder was connected to a watercooling bath and a pelletiser. Steady state operation was obtained after 20 minutes, and the experiment was carried out for 4 hours The granulate was collected and dried as described previously. The granulate contained voids caused by gas evolution in the extrusion process, resulting in low bulk density.

[0372] Example 16:

[0373] A PA-6 / LDPE blend containing 10 wt % PA-6 was prepared as described in Example 14. Example 17:

[0374] A PA-6 / LDPE blend containing 10 wt % PA-6 was prepared as described in Example 15. As in example 15, the granulate contained voids caused by gas evolution in the extrusion process, resulting in low bulk density.

[0375] The results are shown in Table 19 and Figure 21.

[0376] ‘Calculated using the conversion of PA-6.**g / 10 minutes at 2.16 kg load

[0377] Table 19

[0378] The results from examples 15 and 17 demonstrate that:

[0379] • 92-93 % PA-6 can be removed in a twin-screw extruder using (dry) base (NaOH) in continuous operation using a short residence time (50 seconds). This shows that it is not essential to add water prior to extrusion.

[0380] • The resulting content of PA-6, and / or non-removed degradation products, after pre-treatment is 0 % ±0.4 (SE) and 0.3 ±0.4 (SE) of 5% PA-6 / LDPE and 10 % PA-6 / LDPE, respectively.

[0381] • The treatment resulted in a minimum of 92 % and 93 % conversion of PA-6 for 5% PA-6 / LDPE and 10 % PA-6 / LDPE, respectively, considering that the reported Standard Error of Estimate (SEE) for PA-6% measurements using FTIR is 0.4.

[0382] • The bulk densities of the pre-treated granules are 588 and 314 kg / cm3for pretreated 5% PA-6 / LDPE and 10 % PA-6 / LDPE, respectively. The lower bulk density for the 10 %PA-6 / LDPE sample is thought to be due to voids forming as a consequence of gas evolution.

[0383] This example demonstrates that 92-93 % PA-6 can be removed continuously in a twin- screw extruder using base (NaOH) with a short residence time (50 seconds).

[0384] Examples 18-21

[0385] Example 18: Pyrolysis with Example 14 extruded material as feedstock

[0386] The extruded and dried PA-6 / LDPE pellets from Example 14 were fed to the Coperion K-tron gravimetric feeder connected to, and fed in a controlled manner to, a GA-25-25D single screw extruder at 380°C operated at 12.7 RPM, corresponding to 1 Kg / h. The polymer melt exiting the extruder die was continuously fed to the fluidised bed reactor via a conduit connected to an inlet point on the bottom in the fluidised bed reactor. The temperature of the fluidized bed reactor was 450°C and fluidization was maintained by feeding preheated nitrogen at flow rates of 50 NL / min.

[0387] The experiment was carried out at a constant temperature, while the pressure continuously increased in the fluidised bed reactor and in the downstream section. A plug formation was observed in the outlet lines from the fluidised bed reactor, causing challenges in product sampling. This demonstrated operational challenges and instability when using PE / PA-6 blend, without any chemical pre-treatment, as feedstock. The quantity of non-condensable gases was monitored in the gas totalizer and analysed by in-line GC-RGA for composition analysis and the condensed products from the gas / liquid separators were collected in the product storage vessels and weighed.

[0388] Example 19: Pyrolysis with Example 15 extruded material as feedstock

[0389] The experiment was carried out as described in Example 12, at constant pressure and temperature.

[0390] Example 20: Pyrolysis with Example 16 extruded material as feedstock

[0391] This experiment was abandoned due to the plug formation reported in Example 18.

[0392] Example 21 : Pyrolysis with Example 17 extruded material as feedstock

[0393] This experiment was carried out as described in Example 19.

[0394] The results are shown in Table 20 below.

[0395] 1) Calculated. 2) 5.5 kg bed material was used in both example 1 and 2. 3) Transfer line after the reactor before the hot filter.4) The pressure is measured in the line between g / i separator 1 and 2.

[0396] Table 20

[0397] The most significant difference between pretreated PA-6 / LDPE and untreated PA-6 / LDPE is the pressure build-up in the fluidized bed. The pressure in the fluidized bed reactor and downstream increased steadily for untreated 5% PA-6 / LDPE until the experiment ended. The pressure build-up was due to plugging of the reactor outlet lines. This was in stark contrast to LDPE and pretreated PA-6 / LDPE feedstock, which both maintained steady pressure at 0.7-0.8 Bar during the experiments. As a result of the untreated 5% PA / LDPE outcome, 10 % PA-6 in LDPE was therefore not tested in the pilot.

[0398] The fluidized bed reactor temperature increased from 450°C to 470°C during pyrolysis of pretreated (10 %) PA-6 / LDPE. This may be due to the lower feed rate (0.3 kg / h). The reduced feed rate of pretreated PA-6 / LDPE feedstock compared to LDPE, LLDPE and untreated PA-6 / LDPE is believed to be due to its lower bulk density, e.g. voids in granulates caused by the gas formation during extrusion with NaOH, thus reducing the bulk density significantly. It is thought that this will not occur in a continuous operation of the pyrolysis process because the polymer melt will likely undergo compaction after degassing and before feeding to the fluidised bed reactor so the voids will be eliminated. In the present example, the melt was cooled after degassing, therefore the voids were retained.

[0399] Table 21 and Figure 22 shows product yield after pyrolysis of LDPE, pretreated PA-6 / LDPE and untreated 5% PA-6 / LDPE in the product collection vessels.

[0400] Table 21

[0401] The results shows that for the feedstocks, less than 10 wt% gas products was formed. The exception was the pretreated 10 % PA-6 / LDPE, where 22 wt% gas products was formed. This is ascribed to the very low bulk density of this feedstock, causing low feed rate and subsequently higher degree of cracking i.e. more formation of gaseous products.

[0402] Table 22 shows the ultimate analysis by wt % of carbon, hydrogen, and nitrogen, of the resulting product (PA-6 / LDPE, pretreated and untreated) after pyrolysis.

[0403] Table 22 The results show that for 5 % PA-6 / PE and 10 % PA-6 / PE, the remaining content of nitrogen in the pyrolysis products were 181 ppm and 526 ppm, respectively. This is a further reduction compared to the nitrogen content in the melt that was fed to the pyrolysis reactor (Table 17 and Figure 25). This demonstrates that the chemical treatment efficiently reduces the content of nitrogen-containing chemical substances in the resulting pyrolysis product to below 530 wt ppm.

[0404] Table 23 shows bromine Index for LDPE, untreated 5% PA-6 / LDPE and pretreated 5% PA-6 / LDPE for samples collected from vessel 3.

[0405] Table 23

[0406] The results show that the content of unsaturated substances is roughly the same for the three samples irrespective of the feedstock used.

[0407] Figure 23 shows the boiling point distribution of the pyrolysis products obtained from vessels 1 and 3 for LDPE, and pretreated 5% PA-6 / LDPE. The results show that the boiling point distribution is roughly the same for all samples, irrespective of the feedstock used and the different feed rates. For all samples, about 75 % of the collected material had a boiling point below 220 °C corresponding to the naphtha cut.

[0408] Figure 24 shows the PIONA analysis (wt% of paraffins, iso-paraffins, olefins, naphthenes and aromatics) of the pyrolysis product obtained from LDPE, untreated 5% PA / LDPE and pretreated 5% PA-6 / LDPE and 10 % PA-6 / LDPE. The results show that the chemical composition is roughly the same for the four samples irrespective of the feedstock used and the different feed rates. The results also show that highly unsaturated products, typically formed in secondary reactions and at elevated reaction temperatures, are formed in low amount.

[0409] Figure 25 shows the nitrogen content of the PA-6 / PE feedstock (5% and 10 % PA-6), after chemical pretreatment and after pyrolysis. The results show that the nitrogen content is strongly reduced after pretreatment and even further reduced after pyrolysis process, resulting in more than 95% removal of nitrogen for both samples.

[0410] Example 22: Compounding of model waste 5% PET in LLDPE

[0411] A PET / LDPE blend containing 5 wt % PET was prepared by compounding PET (RAMA-PET N180, Indorama Ventures) and LLDPE (Q1018N, Total) in a Coperion ZSK26 twin screw extruder at 230 °C and 500 RPM. The blend was collected as pellets and dried. The sample preparation for compounding is shown in Table 24.

[0412] Table 24

[0413] Examples 23-24

[0414] Example 23: Pyrolysis of model waste 5% PET / PE without pre-treatment

[0415] The extruded and dried PET / LLDPE pellets from Example 22 were fed to the Coperion K-tron gravimetric feeder connected to, and fed in a controlled manner to, a GA-25-25D single screw extruder at 370°C operated at 12 RPM, corresponding to 1 Kg / h feed rate. The polymer melt exiting the extruder die was continuously fed to the fluidised bed reactor via a conduit connected to an inlet point on the bottom in the fluidised bed reactor. The temperature of the fluidized bed reactor was 535 °C and fluidization was maintained by feeding preheated nitrogen using a flow rate 45 NL / min. The experiment was carried out at a constant temperature and pressure in the fluidized bed reactor. The pyrolysis experimental conditions are shown in Table 25 below.

[0416] The quantity of non-condensable gases was monitored in the gas totalizer and the composition was analysed by in-line GC-RGA. The gas composition is shown in Figure 26 and described in Table 26 below. The condensed products from the gas / liquid separators were collected in product storage vessels as described above and weighed. A solid material was observed in the condensed liquid product. The solid material was collected by filtering (Whatman 54), washed several times with heptane and finally dried at 75°C for 10 minutes. The solid filtrate was characterised by FTIR in ATR mode using a Perkin-Elmer Spectrum TWO equipped with a LiTaOs detector and Spectrum 10 software. The spectral range was 450-4000 cm-1and 8 scans were recorded per spectrum with a scan resolution 4 cm-1. Figure 27 shows the FTIR spectrum of the solid from the condensed liquid product obtained from Example 23, compared to a reference library spectrum of benzoic acid, and is an excellent match. The solid was identified as benzoic acid, from PET degradation.

[0417] Example 24: Pyrolysis of model waste 5% PET / PE with pre-treatment

[0418] The extruded and dried PET / LLDPE pellets from Example 22 were premixed with NaOH pellets (molar ratio PET ester groups: NaOH = 2) and subsequently added to the Coperion K-tron gravimetric feeder connected and fed in a controlled manner to a GA- 25-25D single screw extruder, at 370 °C, operated at 12 RPM, corresponding to a feed rate of 0.7-1 Kg / h and approximate residence time of 2-4 minutes for the entire process. The polymer melt exiting the extruder die was continuously fed to a degassing unit connected to the extruder exit. The degassing unit was connected to a slight vacuum to encourage removal of volatiles. The degassing unit was connected to nitrogen, which acted as a stripping agent, to flush out volatiles (and stripping agent) efficiently. The volatile degradation products (e.g. CO, CO2, ethylene glycol, water, oligomers), are removed by the slight vacuum and stripping agent and condensed via an emission condenser, and non-condensables are vented. The degassed polymer melt was continuously fed through a melt pump to the fluidised bed reactor via a conduit connected to an inlet point on the bottom in the fluidised bed reactor.

[0419] The experiment was carried out at constant pressure and temperature in the fluidized bed reactor. The pyrolysis experimental conditions are shown in Table 25 below. The quantity of non-condensable gases was monitored in the gas totalizer and the gas composition was analysed by in-line GC-RGA, using both FID and a TCD detector. The gas composition is shown in Figure 26 and Table 26. The non-condensable products in Example 24 contained less non-hydrocarbon compounds, like CO and CO2, than in Example 23. The condensed products from the gas / liquid separators were collected in the product storage vessels and weighed. No solids were observed in the liquid products.

[0420] *Bypassing the interphase section (no degassing, no chemicals added).

[0421] **With use of a section equipped with a degassing unit.

[0422] Table 25

[0423] Table 26

[0424] The results from Examples 23 and 24 demonstrate that:

[0425] • Chemical pre-treatment of mixed polymer waste (PE / PET) reduces the content of non-hydrocarbon compounds, e.g. CO and CO2, in the non-condensable product mixture from the pyrolysis reactor, hence the overall carbon loss is reduced.

[0426] • Direct pyrolysis of mixed polymer waste (PE / PET) results in benzoic acid that precipitates in the condensed liquid product.

[0427] • Chemical pre-treatment of mixed polymer waste (PE / PET) alleviates the presence of benzoic acid in the condensed pyrolysis product. Hence, plugging in transfer lines due to accumulation of solid degradation products is completely avoided. This is otherwise a challenge when plastic waste containing large amounts of PET is fed to a pyrolysis reactor.

[0428] • For mixed polymer waste (PE / PET), the consecutive continuous processes of chemical pre-treatment, pyrolysis and product collection have been successfully performed.

[0429] Example 25-32:

[0430] Three real mixed polymer waste (MPW) samples were treated. A description of the three mixed polymer waste samples, along with the pretreatment applied, is set out below in Table 27. A description of Examples 25-32, employing these materials, is set out in Table 28. In the column entitled “Process” further pretreatment steps are set out, and the resulting product is set out in the next column. In some cases, this product underwent a further pre-treatment step, e.g. MPW-1 was compounded to give MPW-1A, which underwent a further pretreatment 1 or 2 to give MPW-1 B1 or MPW-1 B2 and so on. All products after pyrolysis have a “-C” in their name.

[0431] Table 27

[0432] Table 28

[0433] Example 25: Compounding of mixed polymer waste MPW-1

[0434] The MPW-1 sample flakes was compounded to produce granulates in a Coperion ZSK18 twin screw extruder operated at 185 °C and 500 RPM. The melt string was cooled in a water bath, pelletized and dried at 100 °C for analysis and subsequent chemical pretreatment process. The compounded sample MPW-1A was analysed in advance with FTIR to measure the content of PET, PVC, PA, PP, PE and an ash test coupled with elemental dispersive spectroscopy (EDS) was carried out to measure the ash content to tailor a recipe for pre-treatment. The composition is described in Table 29.

[0435] Example 26: Pretreatment of mixed polymer waste MPW-1 A

[0436] The compounded MPW-1A material was premixed with dry Ca(OH)2 pellets (Sigma-Aldrich) using an amount corresponding to the molar ratio PVC:Ca(OH)2 = 1 to neutralise HCI formed during PVC decomposition. The pre-mixed blend was subsequently added to a Coperion K-Tron gravimetric feeder connected to a Coperion ZSK18 twin screw extruder operated at 350 °C and 500 RPM (pre-treatment 1). The granulate was collected and dried as described previously. In the next step (pretreatment 2), the MPW-1 B1 granulates were extruded with NaOH and 1 wt. % water to avoid plugging in feed lines from organic and / or inorganic residues. The pre-mixed blend was subsequently added to a Coperion K-Tron gravimetric feeder connected to a Coperion ZSK18 twin screw extruder operated at 230 °C and 500 RPM. The extruder barrel was equipped with a devolatilization outlet close to the extruder die, and a slight vacuum was used. The melt string was cooled in a water bath, pelletized and dried at 100 °C for analysis and subsequent feeding to the pyrolysis process. This compounded and pre-treated material, MPW-1 B2, was analysed to measure the polymer composition, ash content and composition (Table 29 and 32). Example 27: Pyrolysis of pretreated mixed polymer waste MPW-1 B2

[0437] The pyrolysis of MPW-1 B2 from Example 26 was carried out as described in Example 23, bypassing the interphase section equipped with degassing. The condensed liquid product, MPW-1C, was measured to calculate the yields, and the boiling point distribution was analysed by GC-simulated distillation. The inorganic content was measured by XRF. The results are shown in Table 31 , Table 32 and Figure 27.

[0438] Example 28: Compounding of mixed polymer waste MPW-2

[0439] The MPW-2 sample flakes were compounded to produce granulates in a Coperion ZSK18 twin screw extruder, as described in Example 25. The compounded material is called MPW-2A. The sample MPW-2A was analysed in advance with FTIR to measure the content of PET, PVC, PA, PP, PE and an ash test coupled with elemental dispersive spectroscopy (EDS) was carried out to measure the ash content to tailor a recipe for pre-treatment. Paper was observed in the waste flakes, but not quantified by FTIR analyses. The results are shown in Table 29.

[0440] Example 29: Pretreatment of mixed polymer waste MPW-2A

[0441] The compounded material was premixed with dry NaOH pellets (Sigma-Aldrich) using an amount corresponding to the analysed amount of PET and PA. The pre-mixed blend was subsequently added to a Coperion K-tron gravimetric feeder connected to a Coperion ZSK18 twin screw extruder operated at 350 °C and 200 RPM. The extruder barrel was equipped with a devolatilization outlet close to the extruder die. A slight vacuum was used. The melt string was cooled in a water bath, pelletized and dried at 100 °C for analysis and subsequent feeding to the pyrolysis process. This compounded and pre-treated material, MPW-2B, was analysed with FTIR to measure the polymer composition, and an ash test coupled with EDS was used to measure ash content and its composition (Table 29 and 32). observed in the waste flakes before compounding. The paper content was not quantified. NA = Not analysed.

[0442] Table 29

[0443] Example 30: Pyrolysis of pretreated real waste MPW-2B

[0444] The pyrolysis of MPW-2B from Example 29 was carried out as described in Example 23, bypassing the interphase section equipped with degassing. The condensed liquid product, MPW-2C, was measured to calculate the yields, boiling point distribution by GC-simulated distillation and the chemical composition (weight percent of paraffins, iso-paraffins, olefins, napthenes and aromatics, PIONA) was analysed by DHA. The inorganic content was measured by XRF. The results are shown in Table 31 , Table 32, and Figures 28, 29 and 30.

[0445] Example 31 : Pyrolysis of real waste MPW-3A

[0446] The pyrolysis of MPW-3A compounded material from Example 31 was carried out as described in Example 23, bypassing the interphase section equipped with degassing. The condensed liquid product MPW-3C was measured to calculate the yields and the chemical composition (weight percent of paraffins, iso-paraffins, olefins, napthenes and aromatics, PIONA) was analysed by DHA (Table 31 , Figures 28 and 30).

[0447] Table 30 Figure 28 and Table 31 shows the product distribution of carbon numbers above C6 and below C5 obtained from MPW-1C, MPW-2C and MPW-3C in Examples 27, 30 and 31. The results show only slight variation in the product distribution despite the varying feed compositions.

[0448] Table 31

[0449] Figure 29 shows the boiling point distribution of the pyrolysis product MPW-1C and MPW-2C obtained from combining vessels 2 and 3 for Examples 27 and 30. The results show that the boiling point range is lower for Example 30, compared to Example 27. This is likely due to high PP content (48 %) in the MPW-2B feed. The final boiling point is the same for both samples, irrespective of the composition change of the feed.

[0450] Figure 30 shows the weight percentage of paraffins, iso-paraffins, olefins, napthenes and aromatics (PIONA) of the condensed product MPW-2C and MPW-3C obtained from Examples 30 and 31. The results reflect the variation in the chemical composition of the feed MPW-2B and MPW-3A. The weight percentage of aromatics of Example 30 is higher, probably due to the high PP content in MPW-2B and possibly due to the presence of paper.

[0451] Table 32 shows the inorganic content in the real waste samples MPW-1 B2, and MPW-2B as determined by ash test coupled with EDS and the resulting condensed liquid products produced therefrom in Examples 27 and 30 respectively.

[0452] *Sulfur, phosphorus and chlorine are usually partly evaporated during the ashing process and are expected to have an actual higher concentration than the analysed amount in the waste plastic material samples. ** Measured by XRF.

[0453] Table 32

[0454] The results from the Examples 26, 27, 29, 30 and 31 demonstrate that:

[0455] • The PET and PA content is reduced in MPW-2B with chemical pre-treatment compared to MPW-2A without chemical pre-treatment.

[0456] • The inorganic content in the condensed liquid product is substantially reduced compared to the inorganic content in the pre-treated materials MPW-1 B2 and MPW-2B.

[0457] • Pyrolysis of MPW-1 B2, MPW-2B and MPW-3A shows a condensed product yield in the range 70-80 % and a non-condensable product yield in the range 20-30%, irrespective of their initial polymer composition.

[0458] • For mixed polymer waste, the continuous processes of pyrolysis and product collection have been successfully performed

[0459] • Real waste containing significantly higher amounts of PET and PA was also tested, and produced similar results. This indicates the method is applicable across a spectrum of different waste types.

[0460] Example 32: Regeneration of bed material and elemental composition of the inorganics A sample of the bed material, named BM-1 was collected in Example 27 for a bed material regeneration experiment. 100 g of used bed material, BM-1 was loaded into a quartz tube. The quartz tube was heated in a furnace to 650 °C with a 50 °C / min ramp rate, using flow rates 5-10 L / min 100% N2 as a fluidizing medium. At 650 °C, the fluidizing gas was switched to a mixture of 25% oxygen in N2 for 30 minutes, using 5-10 L / min flow rate. After 30 minutes, the temperature ramped up to 700 °C and kept at this temperature for 3 hours. The bed material was cooled, collected and filtered with a 60 micron filter to remove fine inorganic particles from the bed material. The fine organic particles originated from fillers, pigments and contaminants in the real waste sample as well as side products from chemical pretreatment. Images of the fluidized bed particles, before and after removal of char, as well as after filtering of the fine inorganics, show that inorganic fine particles are effectively removed from the spherical bed particles by filtering.

[0461] The example 32 demonstrates that:

[0462] • Solids from mixed polymer waste may accumulate in the bed material during continuous pyrolysis operation.

[0463] • The bed material may be regenerated by established methods such as decharring and subsequent filtering to avoid accumulation of inorganics in the reactor.

Claims

CLAIMS:

1. A method for producing a hydrocarbon product from mixed polymer waste, preferably plastic waste and / or post consumer plastic waste, wherein said mixed polymer waste comprises 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, based on the total weight of the mixed polymer waste, comprising:(i) feeding said mixed polymer waste into an extruder;(ii) adding chemicals, preferably alkali metal salt and / or alkali earth metal salt, to said mixed polymer waste to degrade said compounds, preferably polymer, comprising heteroatoms;(iii) removing degradation products derived from said compounds, preferably polymer, comprising heteroatoms from said hydrocarbon product; and(iv) pyrolysing the hydrocarbon product in a fluidised bed reactor to obtain pyrolysis product.

2. A method as claimed in claim 1 , wherein said mixed polymer waste comprises 50-99 wt% polyolefins and still more preferably 75-99 wt% polyolefins, based on the total weight of the mixed polymer waste composition, wherein said polyolefins are preferably selected from polyethylene, polypropylene, polystyrene and mixtures thereof.

3. A method as claimed in claim 1 or 2, wherein said mixed polymer waste comprises 1-50 wt%, more preferably 2-35 wt% and yet more preferably 5-30 wt% compounds comprising heteroatoms, based on the total weight of the mixed polymer waste composition, preferably wherein:(i) said compounds comprising heteroatoms are polymers, and preferably polymers comprising heteroatoms selected from polyethylene terephthalate (PET), polyamide (PA), polyurethane (PU), biopolymers (e.g. polylactic acid, polyhydroxyalkanoates), cellulose, poly(ethylene-co-vinyl acetate) (EVA), poly( vinyl alcohol-co-ethylene) (EVOH), polycarbonate, poly(acrylonitrile-co-butadiene-co-styrene) (ABS), poly(styrene- co-acrylonitrile) (SAN), polymethylmethacrylate (PMMA) and mixtures thereof; and / or(ii) said compounds comprising heteroatoms are non-polymeric compounds, preferably additives, and still more preferably antioxidants, acid scavengers, slip agents, antiblock agents, processing aids, fillers, extenders, pigments, nucleation agents,lubricants, antistatic agents, UV stabilisers, anti-fogging agents, flame retardants, and mixtures thereof.

4. A method as claimed in any preceding claim, wherein said extruder is at a temperature of at least 300 °C, preferably 300-400 °C and still more preferably 350-390 °C.

5. A method as claimed in any preceding claim, wherein the residence time of said mixed polymer waste in said extruder is 0.1-20 minutes, preferably 0.5-15 minutes, more preferably 0.5 to 10 minutes, still more preferably 1 to 7 minutes and yet more preferably 1.5 to 5 minutes.

6. A method as claimed in any preceding claim, wherein the degradation products derived from the compounds, preferably polymers, comprising heteroatoms are removed in the form of volatiles and via a devolatization outlet of the extruder, the extruder die or a devolatization unit connected to the extruder exit, and / or wherein the degradation products derived from the compounds, preferably polymers, comprising heteroatoms are removed in the form of solids and via a melt filter.

7. A method as claimed in any preceding claim, wherein the difference in temperature between the hydrocarbon product exiting the extruder and the temperature of the fluidised bed reactor is 50-200 °C, more preferably 60-160 °C and still more preferably 70-130 °C8. A method as claimed in any preceding claim, wherein said pyrolysis is carried out at a temperature of 400-650 °C, preferably 420-600 °C and more preferably 450-550 °C and / or at a pressure of 0.2-3.0 Barg and preferably 0.5-2.2 Barg.

9. A method as claimed in any preceding claim, wherein said fluidised bed comprises heat carrier particles comprising, or consisting, of zirconia, silica, alumina, or mixtures thereof.

10. A method as claimed in any preceding claim, wherein the weight ratio of fluidised bed material to hydrocarbon product feedstock is 40:1 to 3:1 , more preferably 30:1 to 5:1 and still more preferably 20:1 to 5:1.

11. A method as claimed in any preceding claim, wherein said fluidised bed is continuously flushed with pre-heated inert gas, recycled gas, steam or mixtures thereof.

12. A method as claimed in any preceding claim, wherein the residence time in said fluidised bed reactor is 4-120 seconds, more preferably 5-30 seconds and still more preferably 5-10 seconds.

13. A method as claimed in any preceding claim, wherein said pyrolysis product is separated into non-condensable and condensable products, and preferably wherein the yield of condensable products is at least 70 wt%, more preferably at least 80 wt% and yet more preferably at least 90 wt%, based on the total weight of pyrolysis product obtained.

14. A method as claimed in claim 13, wherein said condensable products are suitable for entry into the refinery value chain, e.g. waxes, oils and / or naphthas.

15. A system for producing a pyrolysis product from mixed polymer waste comprising: an extruder for conversion of mixed polymer waste comprising 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, and chemicals, preferably alkali metal salt and / or alkali earth metal salt, into a mixture of hydrocarbon product and degradation products derived from the compounds, preferably polymer, comprising heteroatoms; optionally a melt filter for receiving the mixture of hydrocarbon product and degradation products from the extruder and removing solid degradation products from said hydrocarbon product; a degassing unit for receiving the hydrocarbon product from the extruder, or if present melt filter, and removing volatile degradation products from said hydrocarbon product; and a fluidised bed pyrolysis unit for receiving the hydrocarbon product from the extruder, or if present degassing unit, and pyrolysing said hydrocarbon product to obtain a pyrolysis product.

16. A system for producing a pyrolysis product from mixed polymer waste, comprising: an extruder for conversion of mixed polymer waste comprising 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, and chemicals, preferably alkali metal salt and / or alkali earth metal salt, into a mixture of hydrocarbon product and degradation products derived from the compounds, preferably polymer, comprising heteroatoms, wherein said extruder has a barrel comprising a devolatilization outlet for removing volatile degradation products; optionally a melt filter for receiving the mixture of hydrocarbon product and degradation products from the extruder and removing solid degradation products from said hydrocarbon product; and a fluidised bed pyrolysis unit for receiving the hydrocarbon product from the extruder, or if present degassing unit, and pyrolysing said hydrocarbon product to obtain a pyrolysis product.

17. A method for recycling mixed polymer waste comprising:(i) feeding said mixed polymer waste into an extruder, preferably a single screw extruder;(ii) adding chemicals, preferably alkali metal salt and / or alkali earth metal salt, to said mixed polymer waste to degrade said compounds, preferably polymer, comprising heteroatoms;(iii) removing degradation products derived from said compounds, preferably polymer, comprising heteroatoms from said hydrocarbon product; and(iv) pyrolysing the hydrocarbon product in a fluidised bed reactor to obtain pyrolysis product.

18. A system for recycling mixed polymer waste, comprising: an extruder for conversion of mixed polymer waste comprising 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, and chemicals, preferably alkali metal salt and / or alkali earth metal salt, into a mixture of hydrocarbon product and degradation products derived from the compounds, preferably polymer, comprising heteroatoms; optionally a melt filter for receiving the mixture of hydrocarbon product and degradation products from the extruder and removing solid degradation products from said hydrocarbon product;a degassing unit for receiving the hydrocarbon product from the extruder, or if present melt filter, and removing volatile degradation products from said hydrocarbon product; and a fluidised bed pyrolysis unit for receiving the hydrocarbon product from the extruder, or if present the degassing unit, and pyrolysing said hydrocarbon product to obtain a pyrolysis product.

19. A system for recycling mixed polymer waste, comprises: an extruder for conversion of mixed polymer waste comprising 50-99.5 wt% polyolefins and 0.5-50 wt% compounds, preferably polymer, comprising heteroatoms, and chemicals, preferably alkali metal salt and / or alkali earth metal salt, into a mixture of hydrocarbon product and degradation products derived from the compounds, preferably polymer, comprising heteroatoms, wherein said extruder has a barrel comprising a devolatilization outlet for removing volatile degradation products; optionally a melt filter for receiving the mixture of hydrocarbon product and degradation products from the extruder and removing solid degradation products from said hydrocarbon product; and a fluidised bed pyrolysis unit for receiving the hydrocarbon product from the extruder, or if present degassing unit, and pyrolysing said hydrocarbon product to obtain a pyrolysis product.

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