Device and process for depolymerisation of plastics

Abstract

The present disclosure relates to a depolymerisation of plastic waste using hydrogen and a catalyst. The invention provides a method to control the maximum boiling point of the recovered plastic depolymerisation hydrocarbon products. The depolymerisation reactor is provided with a condenser in fluid connection with the headspace of the reactor and the temperature in the condenser is adapted to maintain the desired products in the gaseous state and to condense the hydrocarbon products having a higher boiling point, which can be reintroduced into the reactor to be further depolymerised.

Description

DEVICE AND PROCESS FOR DEPOLYMERISA TION OF PLASTICSTechnical fieldThe present disclosure relates to a depolymerisation of plastic waste using hydrogen and a catalyst. The invention provides a method to control the maximum boiling point of the recovered plastic depolymerisation hydrocarbon products. The depolymerisation reactor is provided with a condenser in fluid connection with the headspace of the reactor and the temperature in the condenser is adapted to maintain the desired products in the gaseous state and to condense the hydrocarbon products having a higher boiling point, which can be reintroduced into the reactor to be further depolymerised.Background of the inventionPlastic waste is of major environmental concern and efficient methods to recycle waste plastics are more than needed.Transforming plastic waste in a catalytic reaction under hydrogen atmosphere is a chemical method which can produce a large variety of saturated hydrocarbons from methane to waxes with a lower level of contaminant than pyrolysis. The produced hydrocarbons can replace fossil feedstock in the manufacturing of new materials such as plastics.EP4032963A1 disclose Process for the hydro-depolymerisation of polymeric waste material, the process comprising the steps of• providing a feedstock of polymeric waste material;• mixing the feedstock of polymeric waste material with a hydrocracking catalyst comprising a hydrogenating component which comprises at least one of Fe, Mo, W, Ti, Ni, Cr, V, Co, Zr and mixtures thereof supported on an inorganic carrier and comprising a depolymerizing component which is an acidic compound, preferably selected from the group of AI2O3, aluminosilicates, silica and zeolites, in particular from the group of Zeolite Y, Zeolite Beta, Zeolite A, Zeolite X, Zeolite L and mixtures thereof, especially Zeolite Y and Zeolite Beta;• Depolymerizing the mixture in the presence of hydrogen in a reactor at a hydrogen pressure from 20 to 500 bar;• separating the content of the reactor to obtain a liquid or liquefiable hydrodepolymerisation product;• Optionally, re-introducing hydrocracking catalyst and / or hydrogen enriched gas fractions obtained in separation step into the reactor; and• Optionally, collecting gaseous fractions obtained in separation step iv).EP4032963A1 describes a separation process (par.

[0077] ) by preferably extracting both a liquid-phase and a gas-phase stream. Also, hydrogen-enriched gas fractions can be reintroduced into the reactor (par.

[0080] ).US2023109450A1 describes a process for conversion of a plastic feedstock to a liquid lubricant product, comprising:• heating the plastic feedstock in the presence of a hydrogenolysis / hydrocracking catalyst in a conversion reactor with a flow of H2 to a conversion temperature to form a slurry;• holding the slurry at the conversion temperature for a retention time sufficient to convert substantially all of the plastic feedstock to a liquid lubricant;• removing the liquid lubricant from the conversion reactor and flowing the liquid lubricant into a distillation column, wherein the liquid lubricant is separated from the hydrogenolysis / hydrocracking catalyst before the liquid lubricant is flowed into the distillation column;• recovering the hydrogenolysis / hydrocracking catalyst separated from the liquid lubricant and transferring the recovered catalyst to a catalyst filter unit after the liquid lubricant is removed from the conversion reactor;• washing the recovered catalysts in the catalyst filter using a washing solvent introduced into the catalyst filter, wherein any lubricant remaining on the recovered catalysts will be dissolved into the washing solvent during washing;• returning the washed catalyst to the conversion reactor for reuse;• flowing the washing solvent after catalyst washing to the distillation column;• purifying the liquid lubricant and washing solvent in the distillation column to recover solvent;• recovering the purified washing solvent for reuse; and• collecting liquid lubricant products.The liquid is removed from the reactor to be further separated.Although some improvement has been made in the waste plastic valorisation using hydrogen to reduce the level of contaminants, there is still a need to improve the process into a crackable oil having a controlled boiling point, preferably a boiling point lower than a desired limit, as this makes it possible to for example reduce or even avoid large branched hydrocarbons and / or aromatic hydrocarbons in the obtained product. It would furthermore be desirable to optimise the depolymerisation method to obtain hydrocarbon products having thedesired boiling point and improve the efficiency of the process. The present invention aims at solving such problems.Summary of the inventionIn a first aspect, the present invention provides a reactor for a plastic depolymerisation process using hydrogen and a catalyst, wherein such reactor is equipped with a condenser in fluid connection with the headspace of the reactor and wherein the condenser is provided with at least one means for controlling the temperature in the condenser and preferably with at least one means for reintroducing condensed products, into the reactor, wherein the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site.In a second aspect, the present invention provides a plastic depolymerisation process comprising a. providing a plastic feedstock b. reacting the plastic feedstock with hydrogen in a reactor in the presence of a catalyst; and c. recovering plastic depolymerisation hydrocarbon products having a defined maximum boiling point from the reactor, wherein the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site, wherein the reactor is equipped with a condenser in fluid connection with the headspace of the reactor, wherein the condenser is provided with at least one means for controlling the temperature in the condenser, wherein the plastic depolymerisation hydrocarbon product is recovered from the reactor in step c) through the condenser, and wherein the temperature in the condenser is set to a value above the maximum boiling point of the desired plastic depolymerisation hydrocarbon products and below the boiling point of depolymerisation hydrocarbons products that are undesired.In a third aspect, the present invention provides a method for controlling the boiling point of hydrocarbon products obtained by a plastic depolymerisation process in the presence of hydrogen and a catalyst, the method comprising: a. providing a plastic feedstock b. reacting the plastic feedstock with hydrogen in a reactor in the presence of a catalyst; andc. recovering plastic depolymerisation hydrocarbon products having a defined maximum boiling point from the reactor, wherein the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site, wherein the reactor is equipped with a condenser in fluid connection with the headspace of the reactor, wherein the condenser is provided with at least one means for controlling the temperature in the condenser, wherein the plastic depolymerisation hydrocarbon product is recovered from the reactor in step c) through the condenser, and wherein the temperature in the condenser is set to a value above the boiling point of the desired plastic depolymerisation hydrocarbon products and below the boiling point of undesired depolymerisation hydrocarbons products.In a fourth aspect, the present invention provides a method for reducing the viscosity of the reaction mixture in a plastic depolymerisation reactor comprising hydrogen and a catalyst, wherein such process comprises a. extracting a gaseous plastic depolymerisation hydrocarbon product having a defined maximum boiling point and optionally plastic depolymerisation hydrocarbon products having a lower boiling point through a condenser in fluid connection with the headspace of the reactor during the course of the reaction, b. condensing in the condenser any plastic depolymerisation hydrocarbon product having a boiling point higher than the defined maximum boiling point; and c. reintroducing the plastic depolymerisation hydrocarbon condensed in step b) in the liquid state into the reaction mixture, wherein the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site, wherein the condenser is provided with at least one means for controlling the temperature in the condenser, and wherein the temperature in the condenser is set to a value above the boiling point of the plastic depolymerisation hydrocarbon product to be extracted in step a) and below the boiling point of depolymerisation hydrocarbons products to be condensed in step b.In a fifth aspect, the present invention provides for the use of a condenser for controlling the boiling point of the hydrocarbon product of a plastic depolymerisation process comprising reacting a plastic feedstock with hydrogen in a reactor in the presence of a catalyst,wherein the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site, wherein the condenser is provided in fluid connection with the headspace of the reactor, wherein the condenser is provided with at least one means for controlling the temperature in the condenser, wherein the plastic depolymerisation hydrocarbon product is recovered from the reactor through the condenser, and wherein the temperature in the condenser is set to a value above the boiling point of the desired plastic depolymerisation hydrocarbon products and below the boiling point of undesired depolymerisation hydrocarbons products.In a sixth aspect, the present invention provides a method for accelerating a plastic depolymerisation reaction in a depolymerisation reactor comprising hydrogen and a catalyst, wherein such process comprises a. extracting a gaseous plastic depolymerisation hydrocarbon product having a defined maximum boiling point and optionally plastic depolymerisation hydrocarbon products having a lower boiling point through a condenser in fluid connection with the headspace of the reactor during the course of the reaction, b. condensing in the condenser any plastic depolymerisation hydrocarbon product having a boiling point higher than the defined maximum boiling point; and c. reintroducing the plastic depolymerisation hydrocarbon condensed in step b) in the liquid state into the reaction mixture, wherein the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site, wherein the condenser is provided with at least one means for controlling the temperature in the condenser, and wherein the temperature in the condenser is set to a value above the boiling point of the plastic depolymerisation hydrocarbon product to be extracted in step a) and below the boiling point of depolymerisation hydrocarbons products to be condensed in step b.In a seventh aspect, the present invention provides use of a condenser for reducing the viscosity of the reaction mixture in a plastic depolymerisation reactor comprising hydrogen and a catalyst, wherein the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site,wherein the condenser is provided in fluid connection with the headspace of the reactor, wherein the condenser is provided with at least one means for controlling the temperature in the condenser, wherein at least one plastic depolymerisation hydrocarbon product is recovered from the reactor through the condenser, and wherein at least one depolymerisation hydrocarbon products is condensed by the condenser and reintroduced into the reactor.Preferably, the temperature in the condenser is set to a value above the boiling point of the recovered plastic depolymerisation hydrocarbon products and below the boiling point of condensed depolymerisation hydrocarbon products.In an eighth aspect, the present invention provides the use of a condenser for accelerating a plastic depolymerisation reaction in a depolymerisation reactor comprising hydrogen and a catalyst, wherein the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site, wherein the condenser is provided in fluid connection with the headspace of the reactor, wherein the condenser is provided with at least one means for controlling the temperature in the condenser, wherein at least one plastic depolymerisation hydrocarbon product is recovered from the reactor through the condenser, and wherein at least one depolymerisation hydrocarbon products is condensed by the condenser and reintroduced into the reactor.Preferably, the temperature in the condenser is set to a value above the boiling point of the recovered plastic depolymerisation hydrocarbon products and below the boiling point of condensed depolymerisation hydrocarbon products.Brief description of the drawings[Fig. 1] provides the product distribution of the hydrocracking run #0036 of Example 1.[Fig. 2] provides the product distribution of the hydrocracking run #0038 of Example 1.[Fig. 3] provides the product distribution of the hydrocracking run #0049 of Example 1.Detailed description of the inventionThe present invention solves the problems of the prior art methods by recovering only the products in gaseous state from the reactor, by recovering such products through a condenserprovided in fluid connection with the headspace of the reactor, by adjusting the temperature in the condenser to target specific hydrocarbon products. The condenser allows to recover the hydrocarbon products having the desired boiling point quickly after their formation and reintroducing products with a higher boiling point into the reactor.The condenser is in fluid connection with the headspace of the reactor. The temperature in the condenser is set so that the hydrocarbon products having the highest desired boiling point can escape the reactor, whereas the hydrocarbons having a higher boiling point condense back into the reactor. This enables to increase the residence time of unwanted products and continuously remove the desired ones. This further allows to decrease the viscosity of the reaction mixture and reduces mass transfer.General definitionsUnless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in art to which the subject matter herein belongs. As used herein, the following definitions are supplied to facilitate the understanding of the present invention.The term “comprise” is generally used in the sense of include, that is to say permitting the presence of one or more features or components. In addition, as used in the specification and claims, the language "comprising" can include analogous embodiments described in terms of “consisting of’ and / or “consisting essentially of’.As used in the specification and claims, the term "and / or" used in a phrase such as "A and / or B" herein is intended to include "A and B", "A or B", "A", and "B".As used in the specification and claims, the singular forms "a", "an" and "the" include plural references unless the context clearly dictates otherwise.Plastic depolymerisation reactionPlastic depolymerisation is meant as the conversion of plastic into smaller hydrocarbon products. The plastic is contacted with a catalyst under a pressurized hydrogen atmosphere at elevated temperatures and reacts to form the said hydrocarbons.The process can be a continuous or semi-continuous process. In a continuous process, plastic feedstock is continuously introduced into the reactor and products are continuously extracted upon their formation. In a semi-continuous process, the plastic feedstock is fed batchwise in the reactor, but the products are extracted in a continuous manner.When a hydrocarbon substance is contacted with a catalyst and hydrogen, different reactions occur depending on the nature of the catalyst and the applied conditions. The presented method can be operated with any type of catalyst, for instance the reactor can be operated for hydrogenation, hydrogenolysis, hydrocracking, hydrodeoxygenation, hydrodesulfurization, hydrodenitrogenation, hydrodemetalation, hydrodealogenation, dearomatization, ring-opening and combination thereof.The used catalyst should have at least a transition metal able to add the hydrogen on the hydrocarbons. Non-limiting examples of active metals include Fe, Ni, Mo, V, W, Ti, Zr, Co, Cr, Cu, Zn, Pt, Pd, Ru, Ir, Re, Os, or any combination thereof.For the purpose of the present invention, the catalyst preferably has an acidic site. A non-limiting list of acidic sites include a zeolite, an alumina, an aluminosilicate, a zirconia, a sulfonated mixed oxide, or any solid acids or super acids, such as niobic acid, tungstic acid or any combination thereof. The acidic site can be mixed intimately with the transition metal site or not. In a particular aspect of the invention, the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site.The transition metal can be supported on a metal oxide or a mixed metal oxide but can also be an organometallic complex acting as a precursor. The support is usually porous with different pores size distribution such as micropores, nano pores and mesopores or a combination thereof.Hydrogen is supplied with pressure increasing the concentration of the gas within the reaction mixture and augment its diffusion and solubility therein.Plastic wasteFor the purpose of the present invention, plastic is preferably waste plastic, preferably post-consumer waste plastic. In a preferred aspect the plastic has a polyolefin content of more than 50wt%, preferably more than 60wt%, more preferably more than 70wt%, even more preferably more than 80wt%, most preferably more than 90%. Polyolefin is preferably defined as polyethylene (PE), polypropylene (PP) and mixtures thereof.Plastic waste can be described in terms of its contamination level and polymer composition. The German association DerGriinePunkt describes several fractions that are representative of the waste polymer recycling market for instance.In a particular aspect, the plastic feedstock is plastic waste consisting in used, residue- emptied, system-compatible items made of plastic (polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyethylene terephthalate (PET)), including secondary components suchas closures, labels, and the like, wherein the plastic purity is higher than or equal to 90.0wt%, wherein the total amount of impurities (such as glass, liquid and cartons), foreign materials (e.g. rubber, stones, wood, textiles, diapers), compostable waste (e.g. food, garden waste)) is less than or equal to 5.0wt%, wherein the content of metal items is less than 2wt%, wherein the content of paper, cardboard and carton is less than or equal to 5.0wt, wherein the PET content is less than or equal to 4.0wt%, where the polyvinyl chloride (PVC) content is less than or equal to 0.5wt%, wherein the content of other impurities is less than or equal to 3.0wt%, and wherein metallic or mineral impurities with a unit weight higher than 100 g are absent. Such plastic waste has been classified by the association DerGriinePunkt as DKR350.In another particular aspect of the invention, the plastic feedstock is plastic waste consisting in used, residue-emptied, system-compatible items made of plastic, wherein the plastic purity is higher than or equal to 85.0wt%, wherein the total content of impurities is less than or equal to 15.0wt%, wherein the content of paper, cardboard and carton is less than or equal to 5.0wt%, wherein the PET content is less than or equal to 7.5wt%, wherein the PVC content is less than or equal to 0.5 wt%, wherein other impurities are less than or equal to 3.0wt%, wherein metallic or mineral impurities with a unit weight higher than 100g are absent, and wherein the content of items smaller than 20 mm is less than or equal to 2.0wt%. Such plastic waste has been classified by the association DerGriinePunkt as DKR323.In another particular aspect of the invention, the plastic feedstock is plastic waste consisting in used, residue-emptied, system compatible items made of plastic foil, wherein the foil area is larger than DIN A4, such as bags, carrier bags and shrink films, including secondary components such as closures, labels, and the like, wherein the plastic purity is higher than or equal to 92.0wt%, wherein the total amount of impurities (such as glass, liquid or cartons), foreign materials (e.g. rubber, stones, wood, textiles, diapers) and compostable waste (e.g. food, garden waste)) is less than or equal to 8.0wt%, wherein the content of paper, cardboard and carton is less than or equal to 1.0wt%, wherein the content of other impurities are less than or equal to 4.0wt%, wherein the content of other plastic items is less than or equal to 4.0wt%, wherein the content of colourless transparent foils greater than DIN A3 is higher than or equal to 42.0wt%, and wherein metallic or mineral impurities with a unit weight higher than 100g are absent. Such plastic waste has been classified by the association DerGriinePunkt as DKR 310-1.In another particular aspect of the invention, the plastic feedstock is plastic waste consisting in used, residue-emptied, system compatible items made of plastic foil with a foil area larger than DIN A4, such as bags, carrier bags and shrink films, including secondarycomponents such as closures, labels, and the like, wherein the plastic purity is higher than or equal to 92.0wt%, wherein the total amount of impurities (such as glass, paper, cardboard, carton, liquid or cartons), aluminium-vaporized plastics, foreign materials (e.g. rubber, stones, wood, textiles, diapers) and compostable waste (e.g. food, garden waste)) is less than or equal to 8.0wt%, wherein the content of other metal items is less than 0.5 wt%, wherein the content of other plastic items is less than or equal to 4.0wt%, and wherein the content of other impurities is less than or equal to 4.0wt%. Such plastic waste has been classified by the association DerGriinePunkt as DKR310-0.In another particular aspect of the invention, the plastic feedstock is plastic waste consisting in used, residue-emptied, system-compatible packaging-typical flexible items made polyolefin plastics (PE, PP and mixtures thereof) such as foils, bags (including, aluminium metallized ones) and rigid polyolefin plastics (such as trays or lids), including secondary components such as closures, labels, and the like, wherein the plastic purity is higher than or equal to 90.0wt%, wherein the total amount of impurities (such as glass, other plastic items, foreign materials (e.g. rubber, stones, wood, textiles, diapers) and compostable waste (e.g. food, garden waste)) is less than or equal to 15.0wt%, wherein the content of paper, cardboard and carton is less than or equal to 3.0wt%, wherein the content of PET items is less than or equal to 5.0wt%, wherein the content of expanded polystyrene (EPS) items is less than or equal to 0.5wt%, wherein the content of other metal items is less than or equal to 1.0wt% and wherein the content of other impurities is less than or equal to 3.0wt%. Such plastic waste has been classified by the association DerGriinePunkt as DKR323-2.In still another particular aspect of the invention, the plastic feedstock is plastic waste consisting in used, residue-emptied, system-compatible items made of packaging-typical plastic (PE, PP, PS), including secondary components such as closures, labels, and the like, wherein the plastic purity is higher than or equal to 90.0wt%, wherein the total content of impurities (such as glass, liquid or cartons), foreign materials (e.g. rubber, stones, wood, textiles, diapers), and compostable waste (e.g. food, garden waste)) is less than or equal to 10.0wt%, wherein the content of metal items is less than or equal to 2.0wt%, where the content of paper, cardboard and carton is less than or equal to 5.0wt%, wherein the content of PET items is less than or equal to 3.0wt%, wherein the content of PVC items is less than or equal to 0.5wt% and wherein the content of other impurities is less than or equal to 3.0wt%. Such plastic waste has been classified by the association DerGriinePunkt as DKR352 mixed plastic (new definition).Plastic waste can also be a combination of any of the above-described plastic feedstocks.In another way, plastic waste can be described in terms of its contamination level and polymer composition. Waste plastics typically have a polyolefin content between 50-90wt%, an ash content between 1-10%, a volatile content between l-10wt%, and other contaminant such as different polymers and biomass, polyester terephthalic, poly amides, rubber, wood, paper, cardboard, aluminium, polyvinyl chloride, polyvinylidene chloride, ethylene-vinyl alcohol, polystyrene, polycarbonates, etc. content of ~5-30wt%.In preferred aspect, PE is defined as being low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE) or any type of similar polyethylene or a mixture thereof.Mixed plastic waste can be separated by any means of separation such as manual sorting, optical sorting, Near Infrared (NIR) sorting, Ramman sorting, sink / float, magnetic sorting, eddy current sorting, wind sifter, size screening and combination thereof. The plastic waste can be cleaned by any means such as washing with water, a solvent, a solvent mixture, hot water and addition of a detergent or addition of an acid or addition of a base or a combination thereof. The plastic waste can be conditioned by size reduction and / or compressed into agglomerates and / or pelletized. Before entering the reactor, the plastic can be filtered in a melt filter or a series of filter to remove solids within the melt such as wood, paper, cardboard, PET, polyamide (PA) or inorganic fillers.All percentages are expressed by weight, relative to the total weight of the plastic feedstock.Reactor and condenserThe present invention uses a temperature-controlled condenser in fluid connection with the headspace of the reactor where the plastic depolymerisation reaction takes place.The reactor can be of any type provided it is provided with a headspace. A headspace is defined as the section of a reactor where gaseous species are present.A condenser is defined as an equipment that reduces the temperature of gas flux, condenses part of it into a liquid and leaves the rest of the flux in the gaseous state.By the effect of the condenser, the product of the depolymerisation reaction in the gas state entering the condenser is split in two different fluxes, wherein hydrocarbon product having a boiling point higher than the temperature in the condenser are condensed to a liquid and reintroduced into the reactor, while hydrocarbon products with a boiling point lower thanthe temperature in the condenser remain in the gaseous state and can be recovered after their passage in the condenser.The condenser is provided with at least one means for controlling the temperature in the condenser. In an aspect of the invention, a mean for controlling the temperature in the condenser is a heat exchanger. The temperature in the condenser can be controlled by a heat exchanger upstream of the condenser. The heat exchanger fluid can be heated or cooled through an external heating / cooling unit, allowing the heat exchanger to heat or cool in the condenser, for example to provide or remove heat from the product stream to control the hydrocarbon chain length. The external heating and / or cooling unit can heat the heat exchanger fluid with an electrical heater, or a gas burner for example. The heat can also be integrated from another section of the process that requires cooling, for instance the reactor cooling circuit. The external heating and / or cooling unit can cool the heat exchanger fluid down, by an active or passive means of cooling. An example of passive cooling can be, but is not limited to, passing the heat exchanger fluid through a coil in contact with water or air at ambient conditions. Means of active cooling can be, but are not limited to, an air cooler (fan), a liquid cooler (in the form of another heat exchanger), or an integrated heat exchange with any stream requiring heat, such as but not limited to, the hydrogen feed stream, and / or the polymer melt feed stream. In another aspect of the invention, another mean for controlling the temperature in the condenser is by addition of an external fluid. The temperature in the condenser can also be controlled by the addition of an external fluid in the condenser. The external fluid can be added at defined temperatures to be able to heat or cool the product inside the condenser and hence control the temperature in the condenser. The external fluid can be, but not limited to, water, steam, hydrogen, nitrogen, product from the process.The condenser can be located above the reactor so that the liquid flows directly back into the reactor. Alternatively, it can also be in a separate vessel, in which case the liquid can be reintroduced into the reactor using a pump. Both options achieve the same objective of increasing the residence time of the condensed liquid within the reactor.Catalytic reactions involving hydrogen and plastic waste are often operated at elevated pressure of hydrogen selected from 5 to 200 bar and elevated temperature selected from 200°C to 500°C or from 250°C to 500°C, or from 300° to 500°C. As the boiling point of the hydrocarbons escaping the reactor depends on the temperature and pressure in the reactor, the temperature in the condenser is set to the maximum boiling point of the desired hydrocarbon products under the conditions of temperature and pressure prevailing in the reactor. As a consequence, unless otherwise indicated, each occurrence of the terms "boiling point" in thepresent application is to be understood as the boiling point under the conditions of temperature and pressure prevailing in the reactor. The skilled person, knowing the pressure and temperature conditions applied in the reactor can determine the boiling point of a desired hydrocarbon at such temperature and pressure based on his common general knowledge, for example based on tables and charts available from the literature as well as calculation solving the cubic equation of state such as the Soave-Redlich-Kwong (SRK) or Peng-Robinson, or by mere trial and error. Therefore, depending on the applied pressure and temperature in the reactor, the temperature in the condenser needs to be adjusted to the boiling point of the desired hydrocarbons, so that such products can escape the reactor.In addition, the hydrogen flow has an impact on the product distribution, as higher flows will force longer hydrocarbons to flow out of the reactor and therefore the temperature in the condenser should be decreased. In some aspects of the invention, the hydrogen flow is selected from 5 to 400 NL / h per litre of reactor, or from 10 to 400 NL / h per litre of reactor, or from 25 to 400 NL / h per litre of reactor, or from 5 to 350 NL / h per litre of reactor, or from 5 to 300 NL / h per litre of reactor, or from 5 to 250 NL / h per litre of reactor. The combination between pressure, temperature and hydrogen flow contribute to determining at which temperature the condenser needs to be operated on to let the products having the desired boiling point escape the reactor. Therefore, in a preferred aspect the condenser is set to the maximum boiling point of the desired hydrocarbon products, wherein such boiling point is defined as the boiling point under the conditions of temperature, pressure and hydrogen flow prevailing in the reactor. Although it is possible to take into account only the pressure and temperature in the reactor, the control of the recovered product types is improved by determining the molecule having the maximum boiling point allowed to escape the reactor by setting the temperature in the condenser taking into account not only the temperature and the pressure in the reactor, but also the hydrogen flow.Therefore, unless otherwise indicated, each occurrence of the terms "boiling point" in the present application is to be understood as the boiling point under the conditions of temperature and pressure prevailing in the reactor, preferably under the conditions of temperature, pressure and hydrogen flow prevailing in the reactor.In a preferred aspect of the invention, the temperature in the condenser is set to a temperature below the temperature prevailing in the reactor, preferably the temperature in the condenser is selected from 30° to 400°C, or from 50°C to 280°C, or from 30° to 280°C. In another aspect of the invention, the temperature in the condenser is at least 30°C or at least 50°C and below the temperature prevailing in the reactor.The unique utilisation of a temperature-controlled condenser enables to operate the reactor continuously at different sets of pressures, temperatures and hydrogen flow rate to keep the boiling point of the products in the desired range. Therefore, any type of reaction involving plastic waste as described above and using hydrogen and a catalyst can be performed within the reactor.Furthermore, the condensed liquid that is re-injected into the reactor has a lower viscosity than the plastic that is injected is advantageous, due to the removal of the recovered products. This is advantageous as it effectively decreases the viscosity of the reaction mixture and therefore reduce the mass transfer inside the reactor, which in turn accelerates the reaction.In a particular aspect, the condensed liquid is mixed with the plastic feedstock before entering the reactor. This advantageously reduces the energy required to melt and transport the plastic into the reactor.In another particular aspect, the condensed liquid is re-introduced into the reactor together with the hydrogen feed. This advantageously improves gas-liquid mixing.In a further particular aspect, the condensed liquid is reintroduced into the reactor in admixture with both plastic feedstock and hydrogen.In a particular aspect, the reactor is provided with at least one mixing means. Any type of mixing means can be used, for instance a static mixer, a pump an eductor / ejector and / or a mechanical agitator can be used.Hydrocarbon productsThe hydrocarbon products can be defined as waxes, liquids, gases, and methane composed of at least carbon and hydrogen atoms, but can also possess heteroatoms and chemical functions such as, but not limited to, alcohols, esters, ethers, amines, or amides and combination thereof.Hydrocarbon liquids are described as a mixture of hydrocarbons characterized by a boiling point at 1 atm below 300°C and a density above 600 kg / m3, composed of linear and branched alkanes with a content higher than or equal to 70wt% with an aromatic content of less than or equal to 10wt%.Hydrocarbon solids or waxes are hydrocarbon chains shorter than the polymers present in the plastic feedstock, which are described as having a boiling point at 1 atm above 300°C and a density above 750 kg / m3composed of linear or branched alkanes with a content higher than or equal to 70wt% and with an aromatic content of less than or equal to 10wt%.Gaseous hydrocarbons are described as being composed of 2 to 5 carbon atoms in their longest chain.The condenser is for example conveniently operated to recover hydrocarbon products having a boiling point at 1 atm lower than the temperature prevailing in the reactor, such as hydrocarbons having a boiling point at 1 atm lower than 300°C, to recover hydrocarbons having a boiling point at 1 atm lower than 220°C, to recover hydrocarbons having a boiling point at 1 atm lower than 150°C, or to recover hydrocarbons having a boiling point at 1 atm lower than 70°C.ExamplesExample 1:1. Equipment usedA continuous plastic hydrocracking pilot rig was designed. Waste plastic was molten, degassed and pressurized in a twin-screw extruder. The pressurized molten plastic was continuously injected into a stirred vessel (reactor) equipped with different agitators such as normal impellers or gas diffusion impellers. The hydrogen was dosed using a mass flow controller, then heated in a tube-in-tube heat exchanger and injected into the reactor either from the bottom or from the top. The head space of the reactor was connected to a condenser. The condenser consists in a tube that can be heated or cooled at a set temperature. The temperature in the condenser was set as provided below in the description of the trials performed. The desired hydrocarbon products were recovered as gas through the condenser tube, while the undesired hydrocarbon products were condensed by the condenser tube and were let to flow as liquids back into the reactor. The gaseous products recovered through the condenser can then be cooled down, in order to further separate the recovered products. In the present case, the gaseous products recovered through the condenser were condensed by a passive cooling spiral, followed by an active cooling spiral equipped with a tube-in-tube type of heat exchanger. The products were then separated into gas and liquid products in a first high-pressure separator and then in a low- pressure separator. The gas obtained after the two separation steps was measured by a wet gas meter and a sample of the gas was sent to a online GC / FID-TCD dedicated for gas analysis. The liquids obtained after the two separation steps were directed towards a sampling chamber or a liquid storage tank where the mass was measured.The liquid samples were analysed by GC-MS equipped with an FID detector. The quantification was performed with an external standard and using the FID response factor method.The present equipment represents an example of one way of performing the process, but other means can be employed as long as the polymer is injected continuously in the reactor, the hydrogen flow is controlled, the temperature and pressure of the reactor is controlled, and the temperature in the condenser is controlled.Alternatively, a semi-batch method could be used were only the hydrogen is fed continuously, and the product are removed continuously via a temperature-controlled condenser.2. TrialA continuous run of plastic waste hydrocracking experiment was conducted at 375°C and 30 bar and a hydrogen flow of 38.4 NL / h per litre of reactor. The reactor was loaded with 26 g of catalyst (synthesis described in EP3884013B1) per litre of reactor. Post-consumer waste plastic was fed at 700 g / h into the reactor. The post-consumer waste used was a DKR310-1 type with an ash content of 3 wt%, and a hydrolysable content of 3.8 wt%.The results are provided in Table 1 and [Fig. 1],Run #0036 shows the liquid product distribution obtained when the condenser temperature was set at 375°C.Run #0038 shows the liquid product distribution obtained when the condenser temperature was set at 325°C.Run #0049 shows the liquid product distribution obtained when the condenser temperature was set at 240°C.[Fig. 1], [Fig. 2] and [Fig. 3] show the product distribution obtained for runs #0036, #0038 and #0049, respectively.

Claims

Claims1. A reactor for a plastic depolymerisation process using hydrogen and a catalyst, wherein such reactor is equipped with a condenser in fluid connection with the headspace of the reactor and wherein the condenser is provided with at least one means for controlling the temperature in the condenser, wherein the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site.

2. A plastic depolymerisation process comprising a) providing a plastic feedstock b) reacting the plastic feedstock with hydrogen in a reactor in the presence of a catalyst; and c) recovering plastic depolymerisation hydrocarbon products having a defined maximum boiling point from the reactor, wherein the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site, wherein the reactor is equipped with a condenser in fluid connection with the headspace of the reactor, wherein the condenser is provided with at least one means for controlling the temperature in the condenser, wherein the plastic depolymerisation hydrocarbon product is recovered from the reactor in step c) through the condenser, wherein the temperature in the condenser is set to a value above the boiling point of the desired plastic depolymerisation hydrocarbon products and below the boiling point of undesired depolymerisation hydrocarbons products.

3. A method for controlling the boiling point in hydrocarbon products obtained by a plastic depolymerisation process in the presence of hydrogen and a catalyst, the method comprising: a) providing a plastic feedstock b) reacting the plastic feedstock with hydrogen in a reactor in the presence of a catalyst; and c) recovering plastic depolymerisation hydrocarbon products having a defined maximum boiling point from the reactor,wherein the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site, wherein the reactor is equipped with a condenser in fluid connection with the headspace of the reactor, wherein the condenser is provided with at least one means for controlling the temperature in the condenser, wherein the plastic depolymerisation hydrocarbon product is recovered from the reactor in step c) through the condenser, and wherein the temperature in the condenser is set to a value above the boiling point of the desired plastic depolymerisation hydrocarbon products and below the boiling point of undesired depolymerisation hydrocarbons products.

4. A method for reducing the viscosity of the reaction mixture in a plastic depolymerisation reactor comprising hydrogen and a catalyst, wherein such process comprises a) extracting a gaseous plastic depolymerisation hydrocarbon product having a defined maximum boiling point and optionally plastic depolymerisation hydrocarbon products having a lower boiling point through a condenser in fluid connection with the headspace of the reactor during the course of the reaction, b) condensing in the condenser any plastic depolymerisation hydrocarbon product having a boiling point higher than the defined maximum boiling point; and c) reintroducing the plastic depolymerisation hydrocarbon condensed in step b) in the liquid state into the reaction mixture, wherein the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site, wherein the condenser is provided with at least one means for controlling the temperature in the condenser, and wherein the temperature in the condenser is set to a value above the boiling point of the plastic depolymerisation hydrocarbon product to be extracted in step a) and below the boiling point of depolymerisation hydrocarbons products to be condensed in step b).

5. Use of a condenser for controlling the boiling point of the hydrocarbon product of a plastic depolymerisation process comprising reacting a plastic feedstock with hydrogen in a reactor in the presence of a catalyst,wherein the catalyst has at least a transition metal, able to add the hydrogen on the hydrocarbons, and an acidic site, wherein the condenser is provided in fluid connection with the headspace of the reactor, wherein the condenser is provided with at least one means for controlling the temperature in the condenser, wherein the plastic depolymerisation hydrocarbon product is recovered from the reactor through the condenser, and wherein the temperature in the condenser is set to a value above the boiling point of the desired plastic depolymerisation hydrocarbon product and below the boiling point of undesired depolymerisation hydrocarbons products.

6. The reactor according to claim 1, the process according to claim 2, the method according to claim 3 or 4 or the use according to claim 5, wherein the plastic depolymerisation process is a semi-batch or continuous process.

7. The process according to claim 2 or 6, the method according to any one of claim 3, 4 or 6 or the use according to claim 5 or 6, wherein the temperature, pressure and hydrogen flow in the reactor are set to values suitable for obtaining at least one plastic depolymerisation hydrocarbon product having the desired maximum boiling point and optionally obtaining one or more additional plastic depolymerisation hydrocarbon product(s) each having a boiling point lower than the maximum boiling point.

8. The process according to any one of claims 2, 6 or 7, the method according to any one of claim 3, 4, 6 or 7, or the use according to any one of claims 5 to 7, wherein the pressure of hydrogen in the reactor is selected from 5 to 200 bar and the temperature in the reactor is selected from 200°C to 500°C.

9. The process according to any one of claims 2, or 6 to 8, the method according to any one of claims 3, 4, or 6 to 8, or the use according to any one of claims 5 to 8, wherein the temperature in the condenser is at least 30°C and below the temperature prevailing in the reactor.

10. The process according to any one of claim 2 or 6 to 9, the method according to any one of claim 3 or 6 to 9, or the use according to any one of claims 5 to 9, wherein any gaseousplastic depolymerisation hydrocarbon product formed in the reactor and having a boiling point higher than the maximum boiling point is condensed in the condenser and reintroduced into the reactor in the liquid state.

11. The reactor according to claim 1 or 6, the process according to any one of claim 2 or 6 to 10, the method according to any one of claim 3, 4 or 6 to 10 or the use according to any one of claims 5 to 10, wherein the plastic is waste plastic, preferably post-consumer waste plastic.

12. The reactor according to any one of claim 1, 6 or 11, the process according to any one of claim 2 or 6 to 11, the method according to any one of claim 3, 4 or 6 to 11 or the use according to any one of claims 5 to 11, wherein the plastic has a polyolefin content of more than 50wt%, preferably more than 60wt%, more preferably more than 70wt%, even more preferably more than 80wt%, most preferably more than 90wt% of polyolefin.

13. The reactor according to any one of claim 1, 6, 11 or 12, the process according to any one of claim 2 or 6 to 12, the method according to any one of claim 3, 4 or 6 to 12 or the use according to any one of claims 5 to 12, wherein the polyolefin is selected from polyethylene (PE), polypropylene (PP) and mixtures thereof.

14. The reactor according to any one of claim 1, 6, or 11 to 13, the process according to any one of claim 2 or 6 to 13, the method according to any one of claim 3, 4 or 6 to 13 or the use according to any one of claims 5 to 13, wherein the plastic is selected from the group consisting of a. used and residue-emptied mixed polyolefins items consisting of items made of PE, PP, PS, PET or mixtures thereof, including secondary components such as closures, labels and the like, wherein the purity is higher than or equal to 90.0wt%, wherein the maximum total amount of impurities is less than or equal to 5.0wt%, wherein the amount of metal impurities is less than 2.0wt%, wherein the amount of paper, cardboard and carton impurities is less than or equal to 5.0wt%, wherein the PET content is less than or equal to 4.0 wt, wherein the amount of PVC is less than or equal to 0.5 wt%, wherein other impurities are less than or equal to 3.0 wt%, and wherein metallic or mineral impurities with a unit weight higher than 100 g are absent;b. mixed polyolefin items, wherein the purity is higher than or equal to 85.0 wt%, wherein the maximum amount of total impurities is less than or equal to 15.0wt%, wherein the content of paper, cardboard and carton is less than or equal to 5.0wt%, wherein the PET content is less than or equal to 7.5wt%, wherein the PVC content is less than or equal to 0.5wt%, wherein the content of other impurities is less than or equal to 3.0wt%, wherein metallic or mineral impurities with a unit weight higher than 100 g are absent, and wherein the content of items smaller than 20 mm is less than or equal to 2.0wt%; c. used, residue-emptied, items made of plastic foil, wherein the foil area is superior to DIN A4, including secondary components such as closures, labels, and the like, wherein the purity is higher than or equal to 92.0wt%, wherein the total amount of impurities is less than or equal to 8.0wt%, wherein the content of paper, cardboard and carton is less than or equal to 1.0wt%, wherein the content of other impurities is less than or equal to 4.0 wt%, wherein the content of other plastic items is less than or equal to 4.0wt%, wherein the content of the colourless transparent plastic foils greater than DIN A3 is higher than or equal to 42.0wt%, and wherein metallic or mineral impurities with a unit weight higher than 100 g are absent; d. used, residue-emptied, items made of plastic foil, wherein the foil area is greater than DIN A4, including secondary components such as closures, labels, and the like, wherein the purity is higher than or equal to 92.0wt%, wherein the total content of impurities is less than or equal to 8.0wt%, wherein the metal items content is less than 0.5wt%, wherein the content of other plastic items is less than or equal to 4.0wt%, and wherein the content of other impurities is less than or equal to 4.0 wt%; e. used, residue-emptied, packaging-typical flexible items made of PO plastics (e.g. PE, PP), including aluminium metallized flexible items and rigid PO plastics, including secondary components such as closures, labels, and the like, wherein the purity is higher than or equal to 90.0wt%, wherein the total content of impurities is less than or equal to 15.0wt%, wherein the content of paper, cardboard, carton and PCC composites is less than or equal to 3.0wt%, wherein the content of PET items is less than or equal to 5.0wt%, wherein the content of EPS items is less than or equal to 0.5wt%, wherein the content of other metalitems is less than or equal to 1 ,0wt%, and wherein the content of other impurities is less than or equal to 3.0 wt%; f. used, residue-emptied, items made of packaging-typical plastic (PE, PP, PS), including secondary components such as closures, labels, and the like, wherein the purity is higher than or equal to 90.0wt%, wherein the total content of impurities is less than or equal to 10.0wt%, wherein the content of metal items is less than or equal to 2.0wt%, wherein the content of paper, cardboard, carton and PCC composites is less than or equal to 5.0wt%, wherein the content of PET items is less than or equal to 3.0wt%, wherein the content of PVC items is less than or equal to 0.5wt% and wherein the content of other impurities is less than or equal to 3.0wt%; and g. mixtures thereof.

15. The reactor according to any one of claim 1, 6, or 11 to 14, the process according to any one of claim 2 or 6 to 14, the method according to any one of claim 3, 4 or 6 to 14 or the use according to any one of claims 5 to 14, wherein the plastic has a. a polyolefin content between 50 and 90wt%, b. an ash content between 1 and 10wt%, c. a volatile content between 1 and 10wt%, and d. other contaminant content between 5 and 30%.

16. The reactor according to any one of claim 1, 6, or 11 to 15, the process according to any one of claim 2 or 6 to 15, the method according to any one of claim 3, 4 or 6 to 15 or the use according to any one of claims 5 to 15, wherein the transition metal of the catalyst is selected from the group consisting of Fe, Ni, Mo, V, W, Ti, Zr, Co, Cr, Cu, Zn, Pt, Pd, Ru, Ir, Re, Os, or any combination thereof, and the acidic site of the catalyst is selected from the group consisting of zeolite, alumina, aluminosilicate, zirconia, sulfonated mixed oxide, solid acids such as niobic acid, or any combination thereof.

17. The process according to any one of claim 2 or 6 to 16, the method according to any one of claim 3, 4 or 6 to 16 or the use according to any one of claims 5 to 16, wherein the temperature in the condenser is set to recover hydrocarbon products having a boiling point at 1 atm below the temperature prevailing in the reactor, such as hydrocarbon products having a boiling point at 1 atm lower than 300°C, to recover hydrocarbons having a boilingpoint at 1 atm lower than 220°C, to recover hydrocarbons having a boiling point at 1 atm lower than 150°C, or to recover hydrocarbons having a boiling at 1 atm lower than 70°C.

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