Process for depolymerizing plastics material

Abstract

The present invention relates to a process for depolymerizing plastics material (1), the process comprising: - heating the plastics material (1) to form a plastic melt (3), - processing a pyrolysis feed (8) comprising the plastic melt (3) and an external solvent (5) in a pyrolysis reactor (9) to generate a pyrolysis product (10), - withdrawing a recycling stream (6) from the pyrolysis product (10) and including at least a portion of said recycling stream (6) in the pyrolysis feed (8), wherein the external solvent (5) is a lipid composition of biological origin.

Description

[0001] Process for depolymerizing plastics material

[0002] The present invention relates to a process for depolymeri zing plastics material .

[0003] Plastics materials have become integral to both industrial and consumer applications , resulting in the generation of substantial volumes of waste . A signi ficant portion of this waste is incinerated, contributing to the release of large amounts of carbon dioxide ( C02) , which exacerbates the environmental impact and highlights the pressing need for more sustainable recycling methods .

[0004] While mechanical recycling is widely practiced, it has inherent limitations . This process typically involves the physical reprocessing of plastics without altering their chemical structure . Steps such as sorting, cleaning, shredding, melting, and re-extruding are typically employed to convert waste plastics into new products . However, with each recycling cycle , the quality of the plastic deteriorates due to thermal and mechanical stress , leading to a reduction in material properties and ultimately limiting the number of times plastics can be mechanically recycled .

[0005] Chemical recycling has emerged as a promising alternative . Chemical recycling involves breaking down plastics at the molecular level , typically through depolymeri zation, to produce monomers or other valuable chemicals . This method can accommodate mixed or contaminated plastic waste streams that mechanical recycling struggles to handle , and it has the potential to recycle plastics multiple times without signi ficant loss in quality . As a result , chemical recycling represents a key pathway toward closing the loop in plastic waste management .

[0006] One of the primary approaches to chemical recycling is pyrolysis , which involves the thermal decomposition of plastics at high temperatures , typically between 400 and 600 ° C, to produce hydrocarbon products commonly referred to as "pyrolysis oils" , " synthetic crude oils" or " syncrudes" . These pyrolysis oils have a range of potential applications , including the use as alternative fuels or as feedstock for the production of new chemicals and materials . A notable advancement in pyrolysis-based recycling is described in WO 2012 / 149590 Al , which outlines a process where plastics material is melted and mixed with a crude oil fraction as an external solvent . The resulting mixture is then processed in a pyrolysis reactor . The use of an external solvent reduces the viscosity of the mixture , enhancing heat trans fer ef ficiency within the reactor . This reduction in viscosity helps minimi ze temperature gradients across the reactor, thereby reducing the risk of locali zed overheating and coking .

[0007] Nevertheless , despite such developments , there is still an urgent need to develop more ef ficient and environmentally sustainable processes for depolymeri zing plastics material , to promote their widespread adoption . Thus , new and improved processes for depolymeri zing plastics material are needed, in particular processes that address at least some of the limitations of the prior art and that enable the ef ficient and environmentally sustainable recycling of plastics material . It is an obj ect of the present invention to provide such processes .

[0008] Therefore , the present invention provides a process for depolymeri zing plastics material , the process comprising :

[0009] - heating the plastics material to form a plastic melt ,

[0010] - processing a pyrolysis feed comprising the plastic melt and an external solvent in a pyrolysis reactor to generate a pyrolysis product ,

[0011] - withdrawing a recycling stream from the pyrolysis product and including at least a portion of said recycling stream in the pyrolysis feed, wherein the external solvent is a lipid composition of biological origin .

[0012] The addition of external solvents to plastic pyrolysis feeds , as disclosed in WO 2012 / 149590 Al , was a signi ficant advancement for processes for depolymeri zing plastics material . As used herein, the "external solvent" can also be referred to as "diluent" or "reaction medium" . As mentioned above , the use of an external solvent reduces the viscosity of the pyrolysis feed, enhancing heat trans fer ef ficiency within the reactor, minimi zing temperature gradients across the reactor and reducing the risk of localized overheating and coking. As regards the type of external solvent, WO 2012 / 149590 Al suggests using a heavy oil with a content of aromatic hydrocarbons of at least 25%.

[0013] In the context of the present invention, it was unexpectedly found that the viscosity-reducing effects sought after in WO 2012 / 149590 Al can not only be achieved with heavy oils and other fossil-based solvents, but also with lipid compositions of biological origin. Surprisingly, it was found that such biological lipid compositions are able to effectively dissolve plastics polymers such as polyolefins, thereby significantly reducing viscosity and improving heat transfer during pyrolysis. Replacing the traditional fossil-based external solvents with lipid compositions of biological origin offers significant advantages, as biological lipid compositions are not only widely available at low costs, but also are renewable materials themselves. Thus, both the economic efficiency and the environmental sustainability of the process can be improved.

[0014] As described in more detail below, it was found in the context of the invention that a wide range of different types of lipid compositions can be used as external solvents. This includes, e.g., oils and fats, waxes, esters, fatty acids, soaps, fatty alcohols and ethers. It was found that such biological lipid compositions are surprisingly effective at solubilizing plastics polymers, in particular polyolefins (PO) such as polyethylene (PE) and polypropylene (PP) .

[0015] Thus, preferably, the plastics material is at least partially dissolved in the external solvent. Thus, preferably, the lipid composition of biological origin is mixed with the plastics material, preferably the plastics melt, whereby the plastics material is at least partially dissolved. This has important advantages, as dissolving the plastics material can reduce its viscosity and increase heat transfer. As used herein, the term "dissolved" preferably refers to the process whereby the plastics material, when mixed with the external solvent, becomes molecularly dispersed within the external solvent. More specifically, the polymer chains contained in the plastics material are molecularly dispersed into the solvent, preferably forming a homogeneous solution. This process involves the breaking down of intermolecular forces within the polymer structure, allowing the polymer to transition from a molten phase into a molecular dispersion within the solvent, where the individual polymer chains are solvated by the external solvent molecules. Preferably, the result is a single-phase solution in which the polymer is uniformly distributed at a molecular level.

[0016] It has been found that lipid compositions of biological origin can be advantageously used in the inventive method without necessitating elaborate pre-treatment . Even low-quality lipid compositions can be successfully used. Impurities present in these compositions can be readily removed during the process, e.g. through conversion under pyrolysis conditions to by-products such as CO2, H20, and coke, or through subsequent removal of salts or other compounds, e.g., in purge streams. This can significantly reduce the costs of the overall process and make the inventive process more sustainable and cost-efficient as a whole .

[0017] Notably, it has further been found that lipids contained in the lipid composition of biological origin can decompose under pyrolysis conditions generating surprisingly stable compounds. Typically, lipid compositions of biological origin contain compounds having long hydrocarbon chains, which are often paraffinic or even n-paraffinic hydrocarbon chains. Such compounds can be converted to terminal alkenes under pyrolysis conditions. For instance, when the lipid composition contains glycerides (especially diglycerides and / or triglycerides) , fatty acids can be cleaved off from the glycerol backbone and the resulting carboxylic acids can undergo decarboxylation, resulting in C02and a terminal alkene. If the fatty acid comprised a paraffinic hydrocarbon chain, a terminal monoalkene is formed. To illustrate, a glyceride containing stearic acid (Ci2) can release C02, forming heptadec-l-ene . Similar decomposition reactions can occur with other types of lipids, such as waxes, fatty acid esters (especially FAME) , fatty acids, etc., which also often contain paraffinic hydrocarbon chains. It was found that the resulting compounds, such as terminal alkenes, are particularly stable under pyrolysis conditions.

[0018] The high stability of such compounds has particular advantages in the context of the recycling stream that is withdrawn from the pyrolysis product. The inventive process comprises the step of withdrawing a recycling stream from the pyrolysis product and including at least a portion of said recycling stream in the pyrolysis feed . In this way, the recycling stream can ful fil a similar function as the external solvent described above , thereby reducing the consumption of external solvent . When a lipid composition is used as external solvent , as described above , a large amount of stable compounds such as terminal olefins can be generated during pyrolysis , which can withstand the pyrolysis conditions and remain in the process through the recycling stream . In this case , these compounds can remain in circulation, and even accumulate in circulation, thus reducing the amount of fresh external solvent that has to be added to the process .

[0019] According to the inventors , without wishing to be bound to a particular theory, the high stability of these compounds , which can allow their accumulation in the recycling stream, can be explained as follows . During the pyrolysis of plastics materials , the decomposition typically occurs through radical mechanisms or p-elimination, leading to the formation of smaller molecular fragments . The chain scission preferentially occurs at branch points or other energetically favorable positions within the polymer , p-elimination results in the removal of hydrogen (H2) and the formation of double bonds , which can further react to form dienes , polyenes , and ultimately aromatic compounds . As a result of this process , compounds can undergo progressive aromati zation, eventually forming highly condensed aromatic systems , such as asphaltenes . Under conditions of prolonged thermal exposure , these systems can lose additional side chains , leaving behind a pure carbon framework, commonly referred to as coke .

[0020] The stability under pyrolysis conditions di f fers between n- paraf finic, iso-paraf finic, olefinic, and aromatic compounds . In the case of n-paraf finic hydrocarbon chains , the absence of branching reduces the likelihood of cracking through p-elimina- tion, as this process is energetically less favorable in straight-chain hydrocarbons . On the other hand, iso-paraf finic compounds , with their branched structures , are more prone to crack at the branch points , generating radicals that can propagate further decomposition .

[0021] Olefinic compounds , due to their unsaturation, are even more reactive under pyrolysis conditions. They are already one step closer to coke formation than paraffinic compounds. In particular, they can undergo cyclization reactions, such as Diels-Alder reactions, resulting in the formation of ring structures. These rings, particularly cyclohexadienes, are often thermally and kinetically unstable and can further decompose, releasing hydrogen or breaking off side chains. The continued aromatization of these systems reduces the hydrogen content while increasing the carbon content, ultimately leading to the formation of coke.

[0022] Compared to olefinic compounds, aromatic compounds are yet another step closer to coke formation. Additionally, they can lead to the formation of phenyl and benzyl radicals. Phenyl radicals are highly reactive, while benzyl radicals exhibit resonance stabilization, making them more stable. The presence of these aromatic radicals can promote the formation of polyaromatic structures, which, under the high-temperature conditions typical of cracking processes, can lead to the accumulation of coke .

[0023] Terminal alkenes, in particular terminal n-alkenes containing only a single terminal double bond and otherwise consisting of n-paraffinic hydrocarbon chains, are therefore much more stable under pyrolysis conditions than compounds contained in traditional fossil-based external solvents, which are typically highly aromatic.

[0024] As mentioned above, WO 2012 / 149590 Al suggests using heavy oils having high contents of aromatic compounds as external solvents. However, in contrast to the teaching of WO 2012 / 149590 Al, it was found in the context of the present invention that low aromatic contents can offer significant advantages. More specifically, for the reasons outlined above, it was found that reducing the content of aromatic compounds in the pyrolysis feed can significantly reduce coke formation. Lipid compositions of biological origin are typically mostly aliphatic, which positively impacts the pyrolysis process. Therefore, it is preferred that the lipid composition comprises less than 5 wt% aromatic compounds, preferably less than 3 wt%, more preferred less than 2 wt%, more preferred less than 1 wt%. Preferably, the content of aromatic compounds is determined according to ASTM D6591-19 or ASTM D5134-21, especially ASTM D6591-19. Preferably, the lipid composition has a Conradson Carbon Residue (CCR) of less than 5 wt%, more preferred less than 3 wt%, more preferred less than 2 wt%, more preferred less than 1 wt%, more preferred less than 0.5 wt%. This reduces the amount of coke formation within the process, decreasing maintenance costs and increasing the efficiency of the process.

[0025] Advantageously, lipid compositions of biological origin typically contain low amounts of sulfur. This is a significant advantage over fossil-based solvents, which often contain high amounts of sulfur. High amounts of sulfur can lead to H2S formation, which can cause corrosion and is highly toxic. Thus, it is preferred that the lipid composition comprises less than 250 ppm, preferably less than 100 ppm, more preferred less than 50 ppm, more preferred less than 10 ppm, more preferred less than 1 ppm sulfur (S) .

[0026] Similarly, lipid compositions of biological origin typically also contain low amounts of nitrogen. As for sulfur, this is advantageous as in this way, few heteroatoms are introduced into the process and thus a higher quality product requiring less purification can ultimately be obtained. Thus, preferably the lipid composition contains less than 500 ppm, preferably less than 100 ppm, more preferred less than 50 ppm, more preferred less than 10 ppm nitrogen (N) .

[0027] For the reasons outlined above, it has been found to be highly advantageous, when the lipid composition comprises compounds having paraffinic, in particular n-paraffinic hydrocarbon chains. As explained above, such compounds can decompose under pyrolysis conditions to form terminal monoalkenes, which were found to withstand the conditions during pyrolysis particularly well and remain in circulation for a longer period of time, thus reducing consumption of the external solvent. Therefore, it is preferred that the lipid composition comprises compounds having paraffinic hydrocarbon chains, especially compounds having n-paraffinic hydrocarbon chains.

[0028] Of note, already moderate amounts, such as 10 wt%, of compounds comprising paraffinic (especially n-paraffinic) hydrocarbon chains are highly advantageous, as it was found that due to the resulting compounds' stability under pyrolysis conditions, these compounds can accumulate in the recycling stream, so that their concentration in the pyrolsis feed increases over time. Nevertheless, these advantageous effects are even more pronounced when higher amounts of such compounds are present. Therefore, the lipid composition preferably comprises at least 10 wt% compounds comprising an n-paraffinic hydrocarbon chain, preferably at least 15 wt%, more preferred at least 20 wt%, more preferred at least 30 wt%, more preferred at least 40 wt%, more preferred at least 50 wt%. As used herein, the wt% are based on the total weight of the lipid composition, i.e., the lipid composition comprises at least X wt% compounds comprising an n-paraffinic hydrocarbon chain based on the total weight of the lipid composition.

[0029] In the context of the invention, it is advantageous when the compounds comprising an n-paraffinic hydrocarbon chain have a high boiling point. This allows easily separating said compounds from shorter chain hydrocarbons obtained from depolymerizing the plastics material, which may be collected as the end product of the process in the form of synthetic crude oil. In this way, the compounds comprising an n-paraffinic hydrocarbon chain can be preferentially kept in the process as part of the recycling stream.

[0030] Therefore, the compounds comprising an n-paraffinic hydrocarbon chain have a boiling point of at least 285 °C, preferably at least 315 °C, more preferred at least 340 °C, more preferred at least 365 °C, more preferred at least 390 °C, more preferred at least 410 °C, more preferred at least 430 °C.

[0031] Thus, preferably, the lipid composition comprises at least

[0032] 10 wt%, preferably at least 15 wt%, more preferred at least 20 wt%, more preferred at least 30 wt%, more preferred at least

[0033] 40 wt%, more preferred at least 50 wt% compounds comprising an n-paraffinic hydrocarbon chain, wherein said compounds have a boiling point of at least 285 °C, preferably at least 315 °C, more preferred at least 340 °C, more preferred at least 365 °C, more preferred at least 390 °C, more preferred at least 410 °C, more preferred at least 430 °C. For clarification, this does not exclude that in addition to the indicated wt% of such compounds, the lipid composition may also comprise further n-paraffinic compounds having lower boiling points. On the other hand, it is preferred that the compounds comprising an n-paraffinic hydrocarbon chain have a boiling point that is not too high. It was found that when the lipid composition comprises a larger proportion of lighter compounds, it can have a better solubilizing effect. Without wishing to be bound to a particular theory, it is assumed that smaller solvent molecules may diffuse more easily into the plastic polymers and disrupt the interactions therein through intercalation.

[0034] Therefore, it is preferred that the compounds comprising an n-paraffinic hydrocarbon chain have a boiling point of at most 800 °C, more preferred at most 750 °C, more preferred at most 700 °C, more preferred at most 650 °C, more preferred at most 600 °C. Preferably, the compounds comprising an n-paraffinic hydrocarbon chain have a boiling point between 285 °C and 800 °C, more preferred between 315 °C and 800 °C, more preferred between 340 °C and 775 °C, more preferred between 365 °C and 750 °C, more preferred between 390 °C and 700 °C, more preferred between 410 °C and 650 °C, more preferred between 430 °C and 600 °C.

[0035] In a preferred embodiment, the compounds comprising an n- paraffinic hydrocarbon chain have an n-paraffinic C16+- hydrocarbon chain, preferably an n-paraffinic Cl 8+-hydrocarbon chain, more preferred an n-paraffinic C20+-hydrocarbon chain, more preferred an n-paraffinic C22+-hydrocarbon chain. For the reasons mentioned above, providing heavier compounds having longer hydrocarbon chains allows to more easily keep these compounds in the process as part of the recycling stream.

[0036] On the other hand, for ensuring a particularly good solubilization, as explained above, it is preferred that the hydrocarbon chains are not too long. Therefore, the compounds comprising an n-paraffinic hydrocarbon chain preferably have an n-paraffinic Cl 6-C120-hydrocarbon chain, preferably an n- paraffinic Cl 8-C80-hydrocarbon chain, more preferred an n- paraffinic C20-C65-hydrocarbon chain. Thus, preferably, the lipid composition comprises at least 10 wt%, preferably at least 15 wt%, more preferred at least 20 wt%, more preferred at least 30 wt%, more preferred at least 40 wt%, more preferred at least 50 wt% compounds comprising an n-paraffinic Cl 6-C120-hydrocarbon chain, preferably an n-paraffinic Cl 8-C80-hydrocarbon chain, more preferred an n-paraffinic C20-C65-hydrocarbon chain. For clarification, this does not exclude that in addition to the indicated wt% of such compounds, the lipid composition may also comprise further compounds having shorter or longer n-paraffinic hydrocarbon chains .

[0037] In the context of the inventive process, any suitable types of compounds comprising n-paraffinic hydrocarbon chains may be used. Preferably, the compounds comprising an n-paraffinic hydrocarbon chain are selected from n-paraffins, aliphatic carboxylic acids, aliphatic alcohols, and derivatives thereof. Aliphatic carboxylic acids may include fatty acids and waxy acids, preferaby having chain lengths as defined above. Similarly, aliphatic alcohols may include fatty alcohols and waxy alcohols, preferaby having chain lengths as defined above. Suitable types of derivates include, but are not limited to, esters, amides, anhydrides and ethers. It is particularly preferred that the compounds comprising an n-paraffinic hydrocarbon chain are n-paraffins. As used herein, "n-paraffins" may also be referred to as "n-alkanes".

[0038] For the reasons outlined above, it is preferred that the lipid composition comprises a high amount of paraffinic compounds, especially compared to olefinic and aromatic compounds. While n- paraffinic compounds are particularly preferred, any types of paraffinic compounds can provide advantages over conventional solvents typically used in plastic pyrolysis processes, which are often highly aromatic. Therefore, it is preferred that the lipid composition comprises at least 20 wt% compounds comprising a paraffinic hydrocarbon chain, preferably at least 30 wt%, more preferred at least 40 wt%, more preferred at least 50 wt%, more preferred at least 60 wt%, more preferred at least 70 wt%, more preferred at least 80 wt%, more preferred at least 90 wt%, more preferred at least 95 wt%, more preferred at least 98 wt%, more preferred at least 99 wt%, more preferred 100 wt%.

[0039] All embodiments specified above for the compounds comprising an n-paraffinic hydrocarbon chain are also preferred for the compounds comprising a paraffinic hydrocarbon chain. Thus, preferably, the compounds comprising a paraffinic hydrocarbon chain have a boiling point of at least 285 °C, preferably at least 315 °C, preferably at least 340 °C, more preferred at least 365 °C, more preferred at least 390 °C, more preferred at least 410 °C, more preferred at least 430 °C. Preferably, the compounds comprising a paraffinic hydrocarbon chain have a boiling point of at most 800 °C, more preferred at most 750 °C, more preferred at most 700 °C, more preferred at most 650 °C, more preferred at most 600 °C. Preferably, the compounds comprising a paraffinic hydrocarbon chain have a boiling point between 285 °C and 800 °C, more preferred between 315 °C and 800 °C, more preferred between 340 °C and 775 °C, more preferred between 365 °C and 750 °C, more preferred between 390 °C and 700 °C, more preferred between 410 °C and 650 °C, more preferred between 430 °C and 600 °C.

[0040] In a preferred embodiment, the compounds comprising a paraffinic hydrocarbon chain have a paraffinic Cl 6+-hydrocarbon chain, preferably a paraffinic Cl 8+-hydrocarbon chain, more preferred a paraffinic C20+-hydrocarbon chain, more preferred a paraffinic C22+-hydrocarbon chain. The compounds comprising a paraffinic hydrocarbon chain preferably have a paraffinic C16- C120-hydrocarbon chain, preferably a paraffinic C18-C80- hydrocarbon chain, more preferred a paraffinic C20-C65- hydrocarbon chain.

[0041] Preferably, the compounds comprising a paraffinic hydrocarbon chain are selected from paraffins, fatty acids, fatty alcohols, and derivatives thereof. Suitable types of derivates include, but are not limited to, fatty acid esters, fatty ester amides, fatty acid anhydrides, and fatty acid ethers .

[0042] While it is preferred that the lipid composition comprises a high amount of paraffinic compounds, n-paraffinic compounds are preferred over iso-paraffinic compounds, for the reasons specified above. In particular, their branched structures make isoparaffinic compounds more prone to radical formation and thus to breakdown under pyrolysis conditions. Therefore, it is preferred that the lipid composition comprises less than 60 wt%, preferably less than 50 wt%, more preferred less than 40 wt%, more preferred less than 30 wt%, more preferred less than 20 wt%, more preferred less than 10 wt%, more preferred less than 5 wt% compounds comprising an iso-paraffinic hydrocarbon chain. It is particularly preferred that the lipid composition comprises less than 60 wt%, preferably less than 50 wt%, more preferred less than 40 wt%, more preferred less than 30 wt%, more preferred less than 20 wt%, more preferred less than 10 wt%, more preferred less than 5 wt% iso-paraffins.

[0043] In a preferred embodiment, the lipid composition contains compounds comprising an n-paraffinic hydrocarbon chain and compounds comprising an iso-paraffinic hydrocarbon chain at a mass ratio of at least 1:1, more preferred at least 2:1, more preferred at least 4:1, more preferred at least 6:1, more preferred at least 8:1, more preferred at least 10:1.

[0044] As outlined above, it has been found in the context of the invention that olefinic compounds contained in the external solvent can be more prone to unfavorable reactions under pyrolysis conditions than paraffinic compounds. On the one hand, double bonds can stabilize radicals and thus promote radical formation. On the other hand, they can lead to diene formation and undergo cyclization reactions resulting in the formation of ring structures and ultimately leading to the formation of coke.

[0045] Therefore, it is preferred that the lipid composition comprises less than 60 wt%, preferably less than 50 wt%, more preferred less than 40 wt%, more preferred less than 30 wt%, more preferred less than 20 wt%, more preferred less than 10 wt%, more preferred less than 5 wt% compounds comprising an olefinic hydrocarbon chain. Preferably, the lipid composition comprises less than 60 wt%, preferably less than 50 wt%, more preferred less than 40 wt%, more preferred less than 30 wt%, more preferred less than 20 wt%, more preferred less than 10 wt%, more preferred less than 5 wt% olefins.

[0046] In a preferred embodiment, the lipid composition contains compounds comprising a paraffinic hydrocarbon chain and compounds comprising an olefinic hydrocabon chain at a mass ratio of at least 1:1, more preferred at least 2:1, more preferred at least 4:1, more preferred at least 6:1, more preferred at least 8:1, more preferred at least 10:1. It is especially preferred that the mass ratio between compounds comprising an n-paraffinic hydrocarbon chain and compounds comprising an olefinic hydrocabon chain is at least 1:1, more preferred at least 2:1, more preferred at least 4:1, more preferred at least 6:1, more preferred at least 8:1, more preferred at least 10:1.

[0047] Preferably, the lipid composition has a bromine number of less than 100 g Br2 / 100 g, more preferred less than 90 g Br2 / 100 g, more preferred less than 80 g Br2 / 100 g, more preferred less than 70 g Br2 / 100 g, more preferred less than 60 g Br2 / 100 g, more preferred less than 50 g Br2 / 100 g, less than 40 g Br2 / 100 g, more preferred less than 30 g Br2 / 100 g, more preferred less than 20 g Br2 / 100 g, more preferred less than 15 g Br2 / 100 g, more preferred less than 10 g Br2 / 100 g, more preferred less than 5 g Br2 / 100 g, more preferred less than 3 g Br2 / 100 g, more preferred less than 2 g Br2 / 100 g, more preferred less than 1 g Br2 / 100 g, more preferred less than 0.5 g Br2 / 100 g. The bromine number, preferably determined according to ASTM D1159-07 (2017 ) , can be considered as a sum parameter for all unsaturated components contained in the lipid composition.

[0048] In addition to the above-described advantageous effects of the n-paraffinic compounds contained in the lipid composition having a high boiling point, it was found to also be advantageous when the lipid composition as a whole has a high boiling range. When the lipid composition has a higher boiling range, less pressure is required to keep the external solvent liquid at high temperatures. Thus, a higher boiling range of the lipid composition allows keeping the process pressure lower, increasing safety and reducing the demands on the equipment used .

[0049] Therefore, in a preferred embodiment, the lipid composition has a boiling range with an IBP (initial boiling point) of at least 150 °C, preferably at least 180 °C.

[0050] It is further preferred that the lipid composition has a boiling range with an FBP (final boiling point) of at most 800 °C, more preferred at most 750 °C, more preferred at most 700 °C, more preferred at most 650 °C, more preferred at most 600 °C.

[0051] Moreover, it is preferred that the lipid composition has a boiling range with a T10 (temperature at 10% volume distilled) of at least 200 °C, more preferred at least 225 °C, more preferred at least 250 °C, more preferred at least 275 °C. Preferably the T10 is between 200 °C and 500 °C, more preferred between 225 °C and 400 °C, more preferred between 250 °C and 300 °C.

[0052] It is further preferred that the lipid composition has a boiling range with a T50 (temperature at 50% volume distilled) of at least 285 °C, more preferred at least 315 °C, more preferred at least 350 °C, more preferred at least 380 °C, more preferred at least 400 °C. Preferably the T50 is between 285 °C and 600 °C, more preferred between 315 °C and 600 °C, more preferred between 350 °C and 550 °C, more preferred between 380 °C and 500 °C, more preferred between 400 °C and 450 °C.

[0053] It is further preferred that the lipid composition has a boiling range with a T90 (temperature at 90% volume distilled) of at most 850 °C, more preferred at most 750 °C, more preferred at most 650 °C, more preferred at most 600 °C. Preferably, the T90 is between 350 °C and 850 °C, more preferred between 375 °C and 750 °C, more preferred between 400 °C and 650 °C, more preferred between 430 °C and 600 °C.

[0054] In a further preferred embodiment, the lipid composition has a Hydrogen / Carbon (H / C) ratio of at least 0.10, preferably at least 0.12, more preferred at least 0.14, more preferred at least 0.15, more preferred at least 0.16, more preferred at least 0.17. As used herein, the H / C ratio refers to the ratio of the lipid composition' s hydrogen content in wt% divided by the carbon content in wt%. A higher H / C ratio thus indicates a higher proportion of hydrogen relative to carbon. This was found to be advantageous, as in this case higher amounts of hydrogen are available during cracking, which can improve pyrolsis and reduce coke formation. A high H / C ratio can be achieved, e.g. by limiting the amount of unsaturated hydrocarbons in the lipid composition. Preferably, the lipid composition has an H / C ratio between 0.10 and 0.20, more preferred between 0.12 and 0.19, more preferred between 0.14 and 0.19, more preferred between 0.15 and 0.19, more preferred between 0.16 and 0.19, more preferred between 0.17 and 0.18.

[0055] It was found that a wide range of different types of lipids can be used for the purposes of the inventive process. Preferably, the lipid composition comprises lipids selected from the group consisting of oils , fats , waxes , esters , acids , soaps , alcohols , ethers , and mixtures thereof .

[0056] In a preferred embodiment , the lipid composition is derived from plants , animals and / or microbes , especially from plants . Thus , preferably, the lipid composition is a lipid composition of plant , animal or microbial origin, especially of plant origin .

[0057] In the context of the invention, the use of plant-derived lipids has proven to be particularly advantageous . According to the inventors , without wishing to be bound to a particular theory, lipid compositions of plant origin often contain longer hydrocarbon chains , which causes the lipid compositions to have higher boiling ranges . This means that less pressure is required to keep the external solvent liquid at high temperatures , which allows keeping the process pressure lower, increasing safety and reducing the demands on the equipment used .

[0058] Preferably, the lipid composition comprises an oil or fat . Preferably, the lipid composition is an oil or fat . Preferably, the oil or fat is an oil or fat of biological origin, preferably of plant , animal , and / or microbial origin, especially of plant origin . As used herein, the terms "oil" and " fat" preferably refer to lipid compositions consisting predominantly of glycerides , especially diglycerides and / or triglycerides . The "oil or fat of biological origin" can preferably also be referred to as a "glyceride composition of biological origin" , i . e . , a composition comprising glycerides . It was found to be particularly advantageous when the lipid composition comprises glycerides . Without wishing to be bound to a particularly theory, the inventors believe that this is due to the fact that glycerides typically have high boiling points and that fatty acids can be cleaved of f one by one during the pyrolysis process .

[0059] Thus , preferably, the lipid composition comprises glycerides , especially diglycerides and / or triglycerides . Preferably, the lipid composition comprises at least 10 wt% glycerides , based on the total weight of the lipid composition, preferably at least 25 wt% , more preferred at least 50 wt% , more preferred at least 80 wt% . Preferably the lipid composition consists essentially of glycerides . The glycerides are preferably of plant , animal, and / or microbial origin, as described above.

[0060] In a preferred embodiment, the oil or fat is of plant origin. Preferably, the lipid composition comprises a vegetable oil; preferably the lipid composition is a vegetable oil. Vegetable oils typically have long fatty acid chains, which causes the lipid compositions to have higher boiling ranges, which can be advantageous as detailed above. Any suitable type of vegetable oil may be used. Preferably, the vegetable oil is selected from the group consisting of rapeseed oil, soybean oil, palm oil, coconut oil, corn oil, carinata oil, peanut oil, olive oil, sunflower oil, and / or castor oil.

[0061] In a particularly preferred embodiment, the oil or fat is Used Cooking Oil (UCO) . Preferably the UCO comprises or consists of oils and / or fats of biological origin, especially vegetable oils as detailed above.

[0062] In an alternative embodiment, which is also preferred, the oil or fat is of animal origin, preferably selected from hoof oil, tallow, fish oil, and / or lard. Animal oils and fats typically contain more saturated hydrocarbon chains and are therefore less olefinic. This can be advantageous, as the olefinic compounds tend do be more reactive under pyrolysis conditions, as explained above.

[0063] In yet another preferred embodiment, the oil or fat is of microbial origin, preferably selected from yeast oils, algae oils, and / or membrane lipids.

[0064] As detailed above, it is particularly preferred when the oil or fat is made from fatty acids having long hydrocarbon chains, as this can allow for a higher boiling range of the external solvent, which means that less pressure is required to keep the external solvent liquid at high temperatures. In a preferred embodiment, the oil or fat comprises fatty acid chains with chain lengths of at least C16 (C16+-fatty acid chains) , preferably at least C18 (C18+-fatty acid chains) . Preferably, at least 30 wt%, more preferred at least 50 wt%, more preferably at least 70 wt% of fatty acid chains present in the oil or fat are C16+-fatty acid chains, preferably C18+-fatty acid chains.

[0065] In is preferred that the oil or fat comprises a large proportion of saturated fatty acid chains. Preferably the mass ratio between saturated and unsaturated fatty acid chains is at least 1:1, preferably at least 2:1, more preferred at least 4:1. The mass ratio can be determined by cleaving of the fatty acids from glycerol backbones and analyzing the distribution of fatty acids in the resulting composition.

[0066] Preferably, the oil or fat has a high smokepoint. When the oil or fat has a high smokepoint, it will be more stable under pyrolysis conditions, as described above. Thus, preferably, the oil or fat has a smokepoint of at least 100 °C, preferably at least 150 °C, more preferred at least 175 °C, more preferred at least 200 °C, more preferred at least 225 °C, more preferred at least 250 °C. The smokepoint is preferably determined using the

[0067] Cleveland Open Cup Method according to AOCS Method Cc 9a-48 (American Oil Chemists' Society (2011) . "AOCS Official Method Cc 9a-48, Smoke, Flash and Fire Points Cleveland Open Cup Method". Official methods and recommended practices of the AOCS - (6th ed.) . Champaign, Ill. : American Oil Chemists' Society) .

[0068] In a further preferred embodiment, the lipid composition comprises fatty acids. Preferably, the lipid composition comprises at least 10 wt% fatty acids, based on the total weight of the lipid composition, preferably at least 25 wt%, more preferred at least 50 wt%, more preferred at least 80 wt%. Preferably the lipid composition consists essentially of fatty acids. Preferably, the fatty acids are C12+-fatty acids, preferably C14+-fatty acids, more preferred C16+-fatty acids, more preferred C18+-fatty acids. As detailed above, longer chain fatty acids were found to be advantageous in the context of the inventive process.

[0069] In a further preferred embodiment, the lipid composition comprises fatty acid esters. Preferably, the lipid composition comprises at least 10 wt% fatty acid esters, based on the total weight of the lipid composition, preferably at least 25 wt%, more preferred at least 50 wt%, more preferred at least 80 wt%. Preferably the lipid composition consists essentially of fatty acid esters. The fatty acid esters preferably are esters consisting of a C12+-fatty acid and an alcohol, preferably of a C14+-fatty acid and an alcohol, more preferred of a C16+-fatty acid and an alcohol, more preferred of a C18+-fatty acid and an alcohol. It is particularly preferred when the alcohol is methanol, i.e., when the ester is a fatty acid methyl ester (FAME) , preferably selected from the group consisting of methyl laurate, methyl myristate, methyl palmitate, methyl stearate, and methyl oleate.

[0070] In a further preferred embodiment, the lipid composition comprises waxes. As used herein, the term "wax" preferably refers to a fatty acid esterified with fatty alcohol. Preferably, the lipid composition comprises at least 10 wt% waxes, based on the total weight of the lipid composition, preferably at least 25 wt%, more preferred at least 50 wt%, more preferred at least 80 wt%. Preferably the lipid composition consists essentially of waxes. Preferably the waxes are esters consisting of a C12 + - fatty acid and a Cl 8+-alcohol , preferably a C14+-fatty acid and a C20+-alcohol , more preferred a C12-C40-fatty acid and a C18- C40-alcohol, more preferred a C14-C35-f atty acid and a C20-C35- alcohol. It was found that such waxes are particularly well suited for inventive process, as they typically have particularly high melting and boiling ranges. Preferably, the waxes are selected from the group consisting of beeswax, wool wax, stearin waxes such as rapseed wax and palm wax, carnauba wax, and candle wax .

[0071] In a further preferred embodiment, the lipid composition comprises soaps. As used herein, the term "soap" preferably refers to a fatty acid salt. Preferably, the lipid composition comprises at least 10 wt% soaps, based on the total weight of the lipid composition, preferably at least 25 wt%, more preferred at least 50 wt%, more preferred at least 80 wt%. Preferably the lipid composition consists essentially of soaps. Preferably, the soaps are salts of C12+-fatty acids, preferably C14+- fatty acids, more preferred C16+-fatty acids, more preferred C18+-fatty acids. Soaps have turned out to be particularly advantageous for the purposes of the invention, as they were found to be particularly stable under pyrolysis conditions.

[0072] In a further preferred embodiment, the lipid composition comprises fatty or waxy alcohols. Preferably, the lipid composition comprises at least 10 wt% fatty or waxy alcohols, based on the total weight of the lipid composition, preferably at least 25 wt%, more preferred at least 50 wt%, more preferred at least 80 wt%. Preferably the lipid composition consists essentially of fatty or waxy alcohols . Fatty and waxy alcohols were also found to be stable under pyrolysis conditions and at the same time to solubili ze plastics material very well . Therefore , they are also particularly preferred for use in the inventive process . Preferably, the fatty or waxy alcohols are C12 + -alcohols , preferably C14+-alcohols , more preferred 016+-alcohols , more preferred Cl 8+-alcohols , more preferred C20+-alcohols , more preferred C24+-alcohols , more preferred C28+-alcohols .

[0073] In yet a further preferred embodiment , the lipid composition comprises ethers , preferably waxy ethers , preferably ethers having the chemical structure R-O-R' , wherein R and R' each independently represent a C8+-hydrocarbon chain, preferably a C12+-hydrocarbon chain, more preferred a 016+-hydrocarbon chain, more preferred a C20+-hydrocarbon chain . Preferably, the lipid composition comprises at least 10 wt% of such ethers , based on the total weight of the lipid composition, preferably at least 25 wt% , more preferred at least 50 wt% , more preferred at least 80 wt% . Preferably the lipid composition consists essentially of of such ethers . Such ethers have high boiling points and were also found to be particularly stable under pyrolysis conditions .

[0074] The plastics material used in the inventive process preferably comprises polyethylene ( PE ) , polypropylene ( PP ) , polystyrene ( PS ) , polyvinyl chloride ( PVC ) , polyethylene terephthalate ( PET ) , polyamide ( PA) , styrene acrylonitrile ( SAN) and / or acrylonitrile butadiene styrene (ABS ) . Preferably, the plastics material may be plastic waste , especially pre-consumer, post-consumer and / or post-industrial plastics . Preferably, the plastics material comprises polyolefins , preferably selected from polyethylene and polypropylene , and / or polystyrene .

[0075] The inventive process has been found to be particularly well suited for recycling polyolefin ( PO) -based plastics material . In particular, it has been found that when the lipid composition contains a high amount of paraf finic compounds , PO-based plastics material can be particularly well solubili zed . Thus , it is preferred that the plastics material comprises PO, preferably selected from PE and / or PP . Preferably, the plastics material comprises at least 20 wt% PO, more preferred at least 50 wt% , more preferred at least 70 wt% , more preferred at least 80 wt% , more preferred at least 90 wt% . In the inventive process, the plastics material is heated to form a plastic melt, wherein the pyrolysis feed comprises the plastic melt. Preferably, the plastics material is heated in a mixer, especially in an extruder. This allows the subsequent pyrolysis to be carried out more energy-ef f iciently and in a shorter amount of time. In the mixer, especially the extruder, the plastics material can preferably also be degassed. This allows producing a uniform mass without gas inclusions, ensuring that a homogeneous pyrolysis product can be obtained through the subsequent pyrolysis.

[0076] Preferably, the plastics material is heated to a temperature of at least 80 °C to form the plastic melt, preferably at least 100 °C. Preferably, the plastics material is heated to a temperature between 80 °C and 450 °C, more preferred between 100 °C and 350 °C. Preferably, the plastics material is heated to the said temperature at a pressure of 10 to 30 bar, preferably 15 to 25 bar.

[0077] Preferably, the lipid composition is heated to a temperature of at least 80 °C, preferably at least 120°C, more preferred at least 150 °C, more preferred at least 200 °C before being added to the plastics material, especially the plastic melt. Preferably the lipid composition is heated to a temperature between 80 °C and 450 °C, preferably between 120 °C and 450 °C, more preferred between 150 °C and 400 °C, more preferred between 200 °C and 350 °C. This allows the mixing to proceed particularly quickly and efficiently.

[0078] In a preferred embodiment, the pyrolysis feed contains the plastic melt and the lipid composition at a weight ratio of between 1:1 and 200:1, more preferred between 2.5:1 and 100:1, more preferred between 5:1 and 20:1 (plastic melt: lipid composition) . It has been found that providing such a ratio between the plastic melt and the lipid composition allows to effectively solubilize the plastic melt and decrease the viscosity of the pyrolysis feed.

[0079] Similarly, it is further preferred that the pyrolysis feed contains the lipid composition and the recycling stream at a weight ratio of between 1:2000 and 1:10, more preferred between 1:1500 and 1:20 (lipid composition : recycling stream) . In a preferred embodiment of the inventive process, the external solvent is mixed with the recycling stream to form a diluent stream, wherein said diluent stream is added to the plastic melt .

[0080] At the timepoint when the diluent stream is added to the plastic melt, the plastic melt preferably has a temperature of at least 80 °C, preferably at least 120 °C, more preferred at least 150 °C, more preferred at least 200 °C. Preferably, the plastic melt has a temperature between 80 °C and 450 °C, preferably between 120 °C and 450 °C, more preferred between 150 °C and 400 °C, more preferred between 200 °C and 350 °C. Alternatively or in addition, the diluent stream can preferably be heated to a temperature of at least 80 °C, preferably at least 120°C, more preferred at least 150 °C, more preferred at least 200 °C before being added to the plastic melt. Preferably the diluent stream has a temperature between 80 °C and 450 °C, preferably between 120 °C and 450 °C, more preferred between 150 °C and 400 °C, more preferred between 200 °C and 350 °C. By increasing the temperature of the plastic melt and / or the diluent stream, the mixing can proceed more quickly and efficiently. This can also allow the subsequent pyrolysis to be carried out more efficiently.

[0081] In a preferred embodiment, the plastics material is depolymerized in the pyrolysis reactor at a temperature of at least 360 °C. However, even higher temperatures may be preferred to allow for more efficient and / or faster depolymerization. Thus, it is preferred if the plastics material is depolymerized at a temperature of at least 400 °C, more preferred at least 440 °C. Preferably the plastics material is depolymerized at a temperature between 360 °C and 510 °C, more preferred between 400 °C and 500 °C, more preferred between 440 °C and 480 °C.

[0082] The depolymerization of the plastics material may be by thermal cracking, without the addition of a catalyst, and / or by catalytic cracking. Thermal cracking is preferred. The depolymerization can be carried out under a substantially oxygen-free atmosphere, particularly under an inert atmosphere, such as under nitrogen. By limiting or excluding oxygen, complete combustion can be prevented more effectively. In a preferred embodiment of the inventive process, the pyrolysis product is separated into a heavy product and a light product, preferably wherein the recycling stream is withdrawn from the heavy product.

[0083] The pyrolysis product may be separated into the heavy product and the light product using any suitable method known to the skilled person. For instance, it may be separated in a separation vessel, preferably wherein the separation vessel is a liquid-gas separation vessel, especially a cyclone. A particularly suitable type of separation vessel is disclosed in WO 2023 / 036751 Al.

[0084] Preferably, the light product has a boiling range with an FBP (final boiling point) below 250 °C, more preferred below 230 °C, more preferred below 210 °C. However, it is also preferred that the FBP is not too low, as this may reduce the amount of the final hydrocarbon product obtained through the process. Therefore, the light product preferably has a boiling range with a FBP above 150 °C, more preferred above 170 °C, more preferred above 190 °C. It is particularly preferred, if the light product has a boiling range with a FBP between 150 and 250 °C, more preferred between 170 and 230 °C, more preferred between 190 and 210 °C.

[0085] The heavy product preferably has a boiling range with an IBP (initial boiling point) of at most 250 °C, more preferred at most 230 °C, more preferred at most 210 °C. Preferably, the IBP is between 150 °C and 250 °C, more preferred between 170 °C and 230 °C, more preferred between 190 °C and 210 °C. Similarly, it is preferred that the heavy product has a boiling range with an T10 (temperature at 10% volume distilled) of at most 250 °C, more preferred at most 230 °C, more preferred at most 210 °C. Preferably, the T10 is between 150 °C and 250 °C, more preferred between 170 °C and 230 °C, more preferred between 190 °C and 210 °C. When the heavy product has a boiling range with such a low IBP and / or T10, this helps ensure that a large proportion of compounds originating from the lipid composition that survive the pyrolysis conditions end up in the heavy product. This is particularly advantageous when the recycling stream is withdrawn from the heavy product, because in this case, a larger proportion of these compounds remains in circulation, reducing external solvent consumption.

[0086] For the same reasons, the recycling stream preferably has a boiling range with an IBP (initial boiling point) of at most 250 °C, more preferred at most 230 °C, more preferred at most 210 °C. Preferably, the IBP is between 150 °C and 250 °C, more preferred between 170 °C and 230 °C, more preferred between 190 °C and 210 °C. Similarly, it is preferred that the recycling stream has a boiling range with an T10 (temperature at 10% volume distilled) of at most 250 °C, more preferred at most 230 °C, more preferred at most 210 °C. Preferably, the T10 is between 150 °C and 250 °C, more preferred between 170 °C and 230 °C, more preferred between 190 °C and 210 °C. As explained above, this helps ensure that the recycling stream can comprise a large proportion of compounds originating from the lipid composition having survived the pyrolysis conditions.

[0087] Unless specified otherwise, all parameters as used herein correspond to parameters at IUPAC SATP-conditions („Standard Ambient Temperature and Pressure") , in particular a temperature of 25 °C and a pressure of 101.300 Pa.

[0088] Percentages (indicated as "%", "wt%" and the like) as used herein correspond to weight per weight (w / w) unless specified otherwise. Similarly, ratios used herein correspond to weight ratios (w / w) unless specified otherwise.

[0089] References to percentages of a given component in any composition refer to the weight percent relative to the total weight of the respective composition unless specified otherwise. Thus, when it is specified that a certain composition comprises X wt% compound A, this means that compound A constitutes X wt% of said composition, i.e., that said composition contains X wt% compound A based on the total weight of said composition. For instance, if it is stated that "the lipid composition comprises at least 10 wt% compounds comprising an n-paraffinic hydrocarbon chain", this means that compounds comprising an n-paraffinic hydrocarbon chain constitute at least 10 wt% of the lipid composition.

[0090] As used herein, the phrase "at least a portion of" or similar phrases refer to any subset of a specified material, component, or stream, which may include part or all of the specified entity. This definition is intended to encompass not only partial quantities but also the entirety of the material , component , or stream in question . Consequently, whenever "at least a portion of" a stream or other entity is mentioned, it is also preferred to use the entire stream or entity . For instance , when it is mentioned that at least a portion of the recycling stream is included in the pyrolysis feed, it is also preferred that the recycling stream ( as a whole ) is included in the pyrolysis feed .

[0091] As used herein, the term "compounds comprising an n-paraf- finic hydrocarbon chain" preferably refers to chemical entities that include at least one unbranched, saturated alkyl chain . Such compounds are herein also referred to as "n-paraf f inic compounds" . In addition, the "compounds comprising an n-paraf f inic hydrocarbon chain" can also be referred to as "compounds comprising a linear alkyl group" . Preferably, these compounds comprise a linear C12+-alkyl group, preferably a linear C14+-alkyl group, more preferred a linear C16+-alkyl group, more preferred a linear C18+-alkyl group .

[0092] Similarly, the term "compounds comprising an iso-paraf finic hydrocarbon chain" preferably refers to chemical entities that include at least one branched, saturated alkyl chain . Such compounds are herein also referred to as " iso-paraf finic compounds" . In addition, the "compounds comprising an iso-paraf- finic hydrocarbon chain" can also be referred to as "compounds comprising a branched alkyl group" . Preferably, these compounds comprise a branched C12+-alkyl group, preferably a branched C14+-alkyl group, more preferred a branched C16+-alkyl group, more preferred a branched C18+-alkyl group .

[0093] The term "paraf finic hydrocarbon chain" , as used herein, preferably encompasses both n-paraf finic and iso-paraf finic hydrocarbon chains . Compounds comprising a paraf finic hydrocarbon chain may also be referred to as "paraf finic compounds" .

[0094] The term "olefinic hydrocarbon chain" , as used herein, preferably refers to a hydrocarbon chain containing at least one carbon-carbon double bond ( C=C ) . Compounds comprising an olefinic hydrocarbon chain may also be referred to as "olefinic compounds" .

[0095] Any hydrocarbon chain referred to herein, such as an n-par- af finic- , iso-paraf finic- , paraf finic- , or olefinic hydrocarbon chain, preferably refers to a hydrocarbon chain comprising at least 12 carbon atoms, preferably at least 14, more preferred at least 16, more preferred at least 18 carbon atoms.

[0096] As used herein, the term "Cx-hydrocarbon chain" refers to hydrocarbon chains having the number of carbon atoms represented by the number "x". The term "Cx+-hydrocarbon chain" refers to hydrocarbon chains having x or more carbon atoms. The term "Cx- Cy-hydrocarbon chain" refers to hydrocarbon chains having from x to y carbon atoms. Thus, for instance, a "Cl 8+-hydrocarbon chain" refers to a hydrocarbon chain having at least 18 carbon atoms, i.e., an alkyl group having at least 18 carbon atoms. A "Cl 8-C12 O-hydrocarbon chain" refers to a hydrocarbon chain having from 18 to 120 carbon atoms, i.e., an alkyl group having from 18 to 120 carbon atoms.

[0097] Similarly, the term "Cx-fatty acid" refers to a fatty acid having a hydrocarbon chain having "x" carbon atoms. "Cx+-fatty acid" refers to a fatty acid having x or more carbon atoms. Thus, a "C16+-fatty acid" is a fatty acid having at least 16 carbon atoms, such as palmitic acid (hexadecanoic acid; C16:0) or stearic acid (octadecanoic acid; C18:0) . The term "Cx-Cy- fatty acid" refers to a fatty acid having from x to y carbon atoms, i.e., a "C12-C40-fatty acid" refers to a fatty acid having from 12 to 40 carbon atoms. Similarly, the term "Cx+-fatty acid chain" refers to a fatty acid chain having at least x carbon atoms, wherein the fatty acid chain may be part of a free fatty acid, a soap, an ester, an ether, and the like. For instance, it may be part of an oil or a fat, in particular a glyceride. The term "Cx-Cy-fatty acid chain" refers to a fatty acid chain having from x to y carbon atoms. Similarly, the term "Cx+-alcohol" refers to an alcohol having a hydrocarbon chain consisting of at least x carbon atoms. The term "Cx-Cy-alcohol" refers to an alcohol having from x to y carbon atoms.

[0098] Carbon number distributions referred to herein are preferably determined according to ASTM D5442-17 (2021 ) , unless specified otherwise.

[0099] Pressures given in "bar" indicate absolute pressures ("bara") , unless specified otherwise.

[0100] Quantities given in "ppm" refer to parts per million on a weight basis (ppmw) , unless indicated otherwise. Thus, 1 ppm as used herein corresponds to 0.0001 wt%.

[0101] Boiling ranges mentioned herein are preferably determined according to ISO 3924:2019, in particular, Procedure A or Procedure B as defined in said standard, or ASTM D86-23ae; preferably ASTM D86-23ae.

[0102] Contents of aromatic compounds are preferably determined according to the standard ASTM D6591-19. Alternatively or in addition, they can also be determined according to ASTM D5134- 21.

[0103] Conradson Carbon Residue (CCR) , as specified herein, is preferably determined according to ISO 10370:2014 or ASTM D189- 06(2019) , preferably ASTM D189-06(2019) .

[0104] Bromine numbers, as specified herein, are preferably determined according to ASTM D1159-07 (2017 ) .

[0105] Hydrogen / carbon (H / C) ratios, as specified herein, are preferably determined as the ratio of the hydrogen wt% and the carbon wt%, wherein the hydrogen and carbon wt% are preferably determined according to ASTM D5291-21.

[0106] Elemental concentrations, such as concentrations of sulfur (S) , oxygen (0) or nitrogen (N) , expressed in ppm or wt%, are preferably determined by elemental analysis. The skilled person is familiar with methods suitable for the various elements. Sulfur (S) concentrations are preferably determined according to ASTM D5453-24. Oxygen (0) concentrations are preferably determined according to ASTM D5622-17. Nitrogen (N) concentrations are preferably determined according to ASTM D4629-17 .

[0107] Figure 1 shows a process flow diagram of an embodiment of the process for depolymerizing plastics material.

[0108] Figure 2A shows a thermogravimetric analysis (TGA) of vegetable oils. Figure 2B shows a TGA of the soaps sodium palmitate and magnesium stearate.

[0109] In the embodiment shown in Figure 1, plastics material 1 is supplied to an extruder 2, in which the plastics material is compacted, molten and / or degassed. The resulting plastic melt 3 is mixed with a diluent stream 4, which comprises an external solvent 5, and a recycling stream 6 comprising a fraction of depolymerized plastics material. The external solvent 5 is a lipid composition of biological origin. The plastic melt 3 is mixed with the diluent stream 4 in a static mixer 7 to form a pyrolysis feed 8. The pyrolysis feed 8 is processed in a pyrolysis reactor 9 at a temperature between 360 °C and 510 °C, whereby the plastics material 1 contained in the pyrolysis feed 8 is depolymerized through thermal cracking, yielding a pyrolysis product 10. Next, the pyrolysis product 10 is conveyed to a separation vessel 11, wherein the pyrolysis product 10 is separated into a heavy product 12 and a light product 13. The light product 13 may be post-treated, e.g., by washing and / or hydrotreating, and may be used as a synthetic crude oil for further applications such as the production of alternative fuels or new chemicals and materials. At least a part of the heavy product 12 is withdrawn as the recycle stream 6, which is recycled and added to the plastic melt 3 as part of the diluent stream 4.

[0110] Example 1: TGA analysis of vegetable oils.

[0111] To determine which types of compounds would be most stable under pyrolysis conditions and thus most suitable for incorporation into the external solvent for the purposes of the invention, thermogravimetric analyses (TGA) of different types of compounds were carried out.

[0112] In a first experiment, two vegetable oils were tested as potential external solvents, specifically coconut oil and partially hydrogenated sunflower oil. Both oils had similar boiling ranges (T50 in the range of 380 °C to 420 °C) . However, due to the hydrogenation of the sunflower oil, they differed in the amount of olefinic hydrocarbon chains. Specifically, the following amounts of unsaturated fatty acids were determined in the two oils:

[0113] Thus, the coconut oil contained significant amounts of a variety of compounds containing olefinic hydrocarbon chains, including 7.3 wt% octadecenoic acid. Such compounds were not detected for the partially hydrogenated sunflower oil, whose main component was determined as octadecanoic acid (76.2 wt%) , i.e., a compound having an n-paraffinic hydrocarbon chain. The difference in olefinic content was also reflected in the bromine numbers of the two oils. For the coconut oil, a bromine number of 3.7 g Br2 / 100g was determined, while for the partially hydrogenated sunflower oil the bromine number was only 2.9 g Br2 / 100g.

[0114] Both oils were tested in TGA experiments, the results of which are shown in Figure 2A. These results clearly show that the partially hydrogenated sunflower oil, containing a higher proportion of compounds having paraffinic hydrocarbon chains, was significantly more stable than the coconut oil having a higher proportion of compounds having olefinic hydrocarbon chains .

[0115] Example 2: Fatty acids and soaps for use as external solvents.

[0116] Experiments were carried out to test the suitability of fatty acids and their respective soaps for use as external solvents in the inventive process. The following fatty acids and soaps were investigated:

[0117] The above comparison shows that the soaps have signi ficantly higher melting and boiling points than the respective fatty acids . This makes them particularly suitable for use as external solvents in the inventive process , as they are very stable under pyrolysis conditions .

[0118] The stability of soaps at high temperatures was further confirmed by TGA experiments , similar as in Example 1 . TGA was conducted for the two soaps sodium palmitate and magnesium stearate . The results are shown in Figure 2B . As can be seen from the figure , both soaps were exceptionally stable up to very high temperatures , making them particularly suitable for use as external solvents for plastic pyrolysis processes .

[0119] Example 3 : Solubilization of plastics material using lipid compositions as external solvents

[0120] For determining the suitability of di f ferent lipid compositions as external solvents , solubility tests were conducted to test the solubili zation of plastics material by these solvents .

[0121] For this purpose , a speci fied amount of shredded ( 4 mm) plastics material ( PO content >80% ) was added to each medium, which had already been heated to 220 ° C, under a nitrogen atmosphere . After 30 minutes , stirring was stopped to allow the insoluble components to settle for 10 minutes . The supernatant solution was decanted and mixed with n-hexane ( 2x, 20 mL each) and then vacuum- filtered to completely remove the lipid composition . The residue was also mixed with n-hexane ( 2x, 20 mL each) and vacuum- filtered to ensure all of the lipid composition was removed . All fractions were subsequently dried in an oven at 120 ° C for 3 hours . Solubility was then determined gravimetrically . The results are shown in the tables below. "Medium" refers to the amount of the lipid composition used. "Feed" refers to the amount of plastics material used. "Melt" refers to the amount of material that successfully dissolved. "Residue" refers to the remaining part that remained undissolved.

[0122] In summary, among the wide range of di f ferent lipid compositions tested, all compositions were surprisingly ef fective at solubili zing the plastics material . Despite the modest temperatures and incubation times used for solubili zation, more than 75 wt% of the plastics feed was dissolved for all lipid compositions tested .

[0123] Several of the lipid compositions were then analyzed further . Physicochemical parameters of these compositions are shown in the table below :

[0124] The compositions of the external solvents were then further analyzed, giving the following results ( all values corresponding to wt% ) :

[0125]

[0126] Example 4 : Stability of n-paraffins and iso-paraffins under pyrolysis conditions . Experiments were conducted to investigate the stability of different types of paraffins under pyrolysis conditions. Specifically, the stability of different n-paraffins and iso-paraffins was tested. As n-paraffins, octadecane and icosane were tested. As iso-paraffins, pristane and squalane were tested.

[0127] To simulate cracking conditions, a stainless-steel reactor with a glass inlet was filled with 10 g of the desired compound. The reactor was flushed three times with N2and was disposed with 5 bar N2pressure at room temperature. The reactor was heated to 460 °C for 1 h (heating rate 250 °C / h) , then cooled to room temperature and the overpressure was released. All phases were separated (liquid, solid) , balanced for the yield factors and analyzed.

[0128] The following mass balances were obtained based on 10 g starting material:

[0129] Additionally, as a further stability parameter, the bromine number of the liquid phases was measured. A higher bromine number is indicative of a higher content of double bonds or reactive aromatic compounds formed under pyrolysis conditions.

[0130] The above results demonstrate the n-paraffins octadecane and ico- sane were significantly more stable under pyrolysis conditions than the iso-paraffins pristane and squalane .

Claims

36Claims :

1. A process for depolymerizing plastics material (1) , the process comprising:- heating the plastics material (1) to form a plastic melt (3) ,- processing a pyrolysis feed (8) comprising the plastic melt(3) and an external solvent (5) in a pyrolysis reactor (9) to generate a pyrolysis product (10) ,- withdrawing a recycling stream (6) from the pyrolysis product (10) and including at least a portion of said recycling stream (6) in the pyrolysis feed (8) , wherein the external solvent (5) is a lipid composition of biological origin.

2. The process according to claim 1, wherein the plastics material (1) is at least partially dissolved in the lipid composition of biological origin.

3. The process according to claim 1 or 2, wherein the lipid composition of biological origin comprises at least 20 wt% compounds comprising a paraffinic Cl 6+-hydrocarbon chain.

4. The process according to any one of claims 1 to 3, wherein the lipid composition of biological origin contains compounds comprising a paraffinic hydrocarbon chain and compounds comprising an olefinic hydrocabon chain at a mass ratio of at least 1:1, more preferred at least 2:1.

5. The process according to any one of claims 1 to 4, wherein the lipid composition of biological origin has a bromine number of less than 100 g Br2 / 100 g, preferably less than 90 g Br2 / 100 g.

6. The process according to any one of claims 1 to 5, wherein the lipid composition of biological origin comprises an oil or fat .

7. The process according to any one of claims 6, wherein the oil or fat is a vegetable oil, preferably having a smokepoint of at least 100 °C.

8. The process according to any one of claims 1 to 7, wherein the lipid composition of biological origin comprises waxes, preferably wherein the waxes are esters consisting of a C12+- fatty acid and a Cl 8+-alcohol .

9. The process according to any one of claims 1 to 8, wherein the lipid composition of biological origin comprises soaps, preferably wherein the soaps are salts of C12+-fatty acids.

10. The process according to any one of claims 1 to 9, wherein the lipid composition comprises less than 5 wt% aromatic compounds .

11. The process according to any one of claims 1 to 10, wherein the lipid composition has a Conradson Carbon Residue (CCR) of less than 5 wt%.

12. The process according to any one of claims 1 to 11, wherein the lipid composition comprises less than 250 ppm sulfur (S) .

13. The process according to any one of claims 1 to 12, wherein the lipid composition has a boiling range with a T50 (tempera- ture at 50% volume distilled) of between 315 °C and 600 °C.

14. The process according to any one of claims 1 to 13, wherein the plastics material comprises at least 20 wt% polyolefins(PO) , preferably selected from polyethylene (PE) and polypropylene (PP) .

15. The process according to any one of claims 1 to 14, wherein the lipid composition is heated to a temperature of at least 120°C before being added to the plastic melt.

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