Process for removing chlorine from plastic mixtures

Abstract

A process for removing chlorine or other halogens from a plastic mixture by passing the mixture through an extruder, a mixer, and one or more devolatilizing vessels.

Description

[Technical Field]

[0001] Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 399,686, filed August 21, 2022.

[0002] The present invention relates to the removal of chlorine and other halogens from mixtures of waste plastics, polymers, and other waste materials using a three-step thermochemical process. [Background technology]

[0003] Introduction In 2019, the United States generated 55.2 million tons of plastic, accounting for 13% of MSW production. More than 368 million tons of plastic were produced worldwide. While the majority of plastic waste is disposed of in landfills through municipal solid waste programs, a significant portion of plastic waste remains in the environment as litter, which is unsightly and potentially harmful to ecosystems. Plastic waste often finds its way into river systems and ultimately into the ocean. According to some estimates, of the 8.3 billion tons of plastic ever produced, 6.3 billion tons became waste, with only 9% of that amount recycled. Plastic recycling involves recovering scrap or waste plastic and reprocessing the material into useful products. However, since China banned the import of waste plastic in 2018, the recycling rate in the United States is estimated to have fallen to just 4.4%.

[0004] The majority of recycled materials, including plastics, are mixed into a single stream that is collected and processed at materials recovery facilities (MRFs). At MRFs, the materials are sorted, cleaned, and packaged for resale. Mechanical recycling, also known as secondary recycling, is the process of converting recycled plastic waste into a reusable form for subsequent manufacturing. The waste plastic material must be further separated into various plastic resins for separate recycling processes, e.g., low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), and polyethylene terephthalate (PET). Unfortunately, mechanical recycling only applies to a small, homogeneous fraction of the recycled polymer.

[0005] Chemical recycling through thermal processes such as pyrolysis or catalytic pyrolysis can convert waste plastics into gaseous and liquid components for creating new materials. The liquid product (e.g., pyrolysis oil) can contain paraffins, isoparaffins, olefins, naphthenes, and aromatics, along with organic chlorides, at concentrations of hundreds to thousands of ppm when the waste plastic stream contains PVC and / or PVDC. Prior art processes are unable to reduce chlorine concentrations to acceptable levels (below 10 ppmw) without costly screening steps to remove most chlorine-containing materials (PVC and PVDC) prior to the pyrolysis unit. Any technology must be able to achieve approximately 99.999% chlorine removal to process 2% of the PVC in the feed to avoid potential contamination and corrosion in downstream processes.

[0006] Shiraga et al. ("Boiling-Point Distributions and Dechlorination of Organic Chlorine Compounds in Oil Obtained from the Degradation of PVC Mixed Plastic," Energy & Fuels 1999, 13, 428-432) found that the Cl content of pyrolysis oil components with carbon numbers of 6 to 12 reached 0.6 wt% (6,000 ppm) in single-step pyrolysis or catalytic pyrolysis experiments at 360-480°C. As a result, a multi-step process has been proposed in which most of the chlorine is removed in a preliminary step and the resulting liquid is then upgraded in a further step.

[0007] Lopez-Urionabarrenechea et al. (2012. "Catalytic stepwise pyrolysis of packaging plastic waste." J. Anal. Appl. Pyrol. 96, 54-62) described a two-step process for the pyrolysis of waste materials, testing a combination of a first low-temperature step without a catalyst and a second step after adding a catalyst. They found that "after the dechlorination step, the system containing the plastic sample had to be cooled to room temperature, the dechlorinated molten sample removed, frozen in liquid nitrogen, crushed in a grinder, mixed with the catalyst, and then reassembled in the reactor for the second catalytic step." Nevertheless, the liquid product contained 0.3 wt.% Cl.

[0008] A stepwise dechlorination process using a single-screw extruder used in a commercial plant by Sapporo Plastics Recycling Co., Ltd. has been described in two publications by Fukushima et al. (Fukushima, et al., "Study on dechlorination technology for municipal waste plastics containing polyvinyl chloride and polyethylene terephthalate," J Mater Cycles Waste Manag (2010) 12:108-122; J Mater Cycles Waste Manag (2009) 11:11-18). The extruder has heating sections for pressurization, metering, mixing, and discharge to produce a liquid mixture containing less than 0.5% Cl, which can be fed to a pyrolysis unit to produce pyrolysis liquid. Separate mixing and devolatilization vessels are not mentioned.

[0009] Price and Wilson (U.S. Pat. No. 5,821,395) disclose a process using an extruder or agitated tank pretreatment to remove chlorine from a waste plastic mixture that is pyrolyzed in a non-catalytic fluidized bed of solids to produce a liquid. Javeed et al. (U.S. Pat. No. 10,829,696) describe a process in which a hydrocarbon stream, a first zeolite catalyst, and a stripping gas are fed to a devolatilizing extruder to produce a liquid stream for upgrading in a pyrolysis or catalytic cracker. DeWhitt (U.S. Pat. No. 7,758,729) discloses a discontinuous (batch) process in which "plastic material in a treatment chamber is heated in stepwise steps through a series of stepped temperature set points...an inert gas vacuum is drawn on the treatment chamber...selectively removing individual by-products corresponding to the temperature set points." In U.S. Patent No. 5,608,136, Mayazawa et al. describe a two-step pyrolysis process in which a mechanically mixed plastic mixture is pyrolyzed under reduced pressure, the vapor product is scrubbed with a basic water wash, cooled, and the concentrated product is catalytically pyrolyzed under high pressure to produce a liquid product. In U.S. Patent No. 6,011,187, Horizoe et al. disclose a process for dechlorinating a mechanically agitated waste plastic mixture by heating it with hot sand in a horizontal screw reactor to produce a low-chlorine material that can be pyrolyzed to form a liquid. None of these publications include a static mixer to promote mixing and enhance chlorine removal.

[0010] Chlorine removal from plastics is a two-step reaction, a relatively fast, low-temperature process followed by a slower process that occurs at high temperatures and requires a long residence time. Extruders and screw-type reactors have a large length-to-diameter (L / D) ratio that is limited by the feasible length of the screw, limiting the residence time within the extruder or screw mixer. Because the second chlorine removal process is slow, the extent of chlorine removal within the extruder is necessarily limited.

[0011] Prior art dechlorination processes often use continuous stirred tank reactors (CSTRs), which require very large volumes to achieve the residence time necessary to remove enough chlorine and reduce the chlorine content to acceptable levels. Furthermore, mixing limits chlorine removal because the newly supplied plastic containing high levels of chlorine disperses with the dechlorinated material to form a homogeneous mixture in the CSTR.

[0012] The present invention provides a three-step process for removing chlorine and other halogens from a mixed plastic waste stream by heating the mixture in an extruder to remove a first portion of the chlorine as HCl, performing long residence time plug flow mixing in a mixing vessel, and pyrolyzing the stream in one or more additional devolatilizer vessels to remove the remaining chlorine to low levels while minimizing the formation of organic chlorides. Similarly, when the mixed plastic feed contains multiple halogens, i.e., chlorine, bromine, iodine, or fluorine, or any combination thereof, the disclosed three-step process removes the combination of halogens. Summary of the Invention

[0013] The present invention relates to a process for removing chlorine from mixed plastic waste streams in a multi-step thermochemical process to achieve acceptably low concentrations of chlorine in the liquid product. Plastics such as PVC and PVDC contain very high chlorine contents (57% and 73% by weight, respectively), so even small amounts of these materials in plastic waste produce significant amounts of chlorine in the mixture. Thermal treatment of chlorine-containing plastic mixtures releases HCl but also produces chlorine-containing hydrocarbon liquids that are harmful to downstream processes. Typical chlorine limits in chemical processing are about 10 ppm or less. The multi-step process of the present invention includes a low-temperature first step carried out in an extruder, a mixing step carried out in a reactor where plug flow conditions are established, and a devolatilization step in a pyrolysis reactor.

[0014] In one aspect, the invention provides a process for removing chlorine from a mixture of plastics, the process comprising: (a) feeding a mixture of plastics having a chlorine content of at least 100 ppm by weight to an extruder; (b) heating the mixture in the extruder to release gases comprising HCl from the molten mixture through at least one degassing port; (c) passing the extruded plastic mixture from b) through a first plug flow high temperature mixing vessel; (d) passing the molten mixture from c) through a devolatilization vessel; and (e) recovering molten plastics having reduced chlorine content from the devolatilization vessel. [Brief explanation of the drawings]

[0015] [Figure 1] 1 shows a schematic diagram of a process for removing chlorine from a plastic mixture. [Figure 2] FIG. 1 shows a schematic diagram of a column for mixing and / or devolatilization of plastic mixtures. [Figure 3] 1 illustrates an embodiment of a mechanical mixing devolatilization vessel useful in the process. DETAILED DESCRIPTION OF THE INVENTION

[0016] Glossary Dechlorination—The term “dechlorination” refers to the removal of chlorine or chlorine-containing compounds, such as, but not limited to, HCl, chlorine-substituted aromatics, paraffins, or olefins, or some combination, from plastics, plastic waste, or mixtures, or some combination thereof, to produce a material having a lower concentration of chlorine than the feed material. Where HCl is indicated, the vapor mixture may contain HCl, or other halogen gases such as HF, HBr, or HI, or some combination, but HCl is the most commonly occurring material because both are derived from PVC or PVDC, which are common plastic materials. Chlorine herein refers to chlorine atoms, ions, or compounds, not the gaseous elemental form of chlorine, Cl, unless otherwise indicated. Where chlorine is indicated, it is understood that the process is equally applicable to any mixture containing the halogens chlorine, bromine, iodine, or fluorine, or any combination thereof, and these processes are contemplated within the scope of this disclosure.

[0017] Devolatilization - The term "devolatilization" refers to the removal of volatiles from a material, usually by heating or exposure to vacuum, or both. Devolatilization is also the process of removing volatiles directly from the extruder during melt extrusion of a polymer. A "devolatilization vessel" is an apparatus in which, during operation, a separate vapor phase is formed above the molten liquid phase to allow vapor removal.

[0018] Fluid - The term "fluid" refers to a gas, a liquid, a mixture of a gas and a liquid, or a gas or liquid containing dispersed solids, liquid droplets, and / or gas bubbles. The terms "gas" and "vapor" have the same meaning and are sometimes used interchangeably.

[0019] Plastic or Polymer - The terms "plastic" and "polymer" are used interchangeably herein. A polymer is a carbon-based (at least 50% by weight C) material composed primarily of repeating units and having a number average molecular weight of at least 100, usually greater than 1000, or even greater than 10,000. Polymers include thermoplastic polymers such as polyethylene, polypropylene, polyester, polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene (ABS) copolymer, polyamide, polyurethane, polyether, polycarbonate, poly(oxide), poly(sulfide), polyarylate, polyetherketone, polyetherimide, polysulfone, polyurethane, polyvinyl alcohol, and polymers produced by polymerization of monomers such as dienes, olefins, styrene, acrylates, acrylonitrile, methacrylates ... These include nitriles, diacids and diols, lactones, diacids and diamines, lactams, vinyl halides, vinyl esters, their block copolymers, and their alloys; thermosetting polymers such as epoxy resins, phenolic resins, melamine resins, alkyd resins, vinyl ester resins, unsaturated polyester resins, crosslinked polyurethanes, polyisocyanurates, and crosslinked elastomers, including, but not limited to, polyisoprene, polybutadiene, styrene-butadiene, styrene-isoprene, and ethylene-propylene-diene monomer polymers and their blends. Polymer mixtures separated from municipal solid waste or other waste streams are suitable feedstocks only if they contain only small amounts of contaminants such as S, N, O, or halogens. Polymers that produce halogenated materials upon thermal decomposition, such as polyvinyl chloride (PVC), polyvinyl dichloride (PVDC), polytetrafluoroethylene (PTFE), and other halogenated polymers, are included in feedstocks for plastics upgrading processes, but often at minimal levels.

[0020] Pyrolysis - The terms "pyrolysis" and "pyrolyzing" are given their conventional meaning in the art and are used to refer to the conversion of compounds, such as solid hydrocarbonaceous materials, by heat, preferably without added or absent O, into one or more other substances, such as volatile organic compounds, gases, and coke. Preferably, the volume fraction of O present in the pyrolysis reaction chamber is 0.5% or less. Pyrolysis can occur with or without a catalyst.

[0021] The term "recovering" has its conventional meaning in process chemistry and can be substituted with the term "obtaining."

[0022] Residence Time - "Residence time" means the actual time under reaction conditions that a material spends in either the active section of the reactor, the heated (or cooled) section, or the volume of the reactor containing the catalyst. In some embodiments, it can be advantageous to control the residence time of the fluidizing fluid or liquid or molten material in the vessel. The residence time of the material in the vessel is defined as the volume of the vessel under process conditions of temperature and pressure divided by the volumetric flow rate of the fluidizing fluid.

[0023] As in standard patent terminology, the term "comprising" means "including" and does not exclude additional components. Any aspect of the invention described in connection with the term "comprising" also includes narrower embodiments in which the term "comprising" is replaced with the narrower terms "consisting essentially of" or "consisting of." As used herein, the terms "includes" or "including" should not be construed as limiting the invention, but rather as listing exemplary components.

[0024] Detailed Description of the Invention 1 shows a schematic diagram of an embodiment of the invention, which includes an extruder with gas generation port(s) that allow evolved HCl or other gases to be removed from the plastic mixture, a mixing vessel (vessel 1) that provides a long residence time for mixing and HCl generation, and one or more devolatilization vessels (vessel 2) that are held at a higher temperature to remove additional chlorine from the system and produce a molten liquid product mixture with a low chlorine content. The extruder, mixer, and one or more devolatilization vessels are in fluid communication so that a molten or liquid phase can flow from the extruder to the one or more devolatilization vessels.

[0025] Plastic feedstocks suitable for use in the present invention include polyethylene (PE), polypropylene (PP), polyacetylene, polybutylene, polyolefins, polyethylene terephthalate (PET), polybutylene terephthalate, polyesters, copolyesters, polycarbonates, polyurethanes, polyamides, polystyrene (PS), polyacetals, epoxies, polycyanurates, polyacrylic acids, polyureas, vinyl esters, polyacrylonitrile, polyamides, polyurethanes, polyethers, polycarbonates, poly(oxides), poly(sulfides), polyarylates, polyetherketones, polyetherimides, polysulfones, polyurethanes, polyvinyl alcohols, polyvinyl chloride (PVC), polyvinyl dichloride (PVDC), polyvinyl acetate, nylons, copolymers such as ethylene-propylene, acrylonitrile-butadiene-styrene (ABS), nitrile rubber, natural and synthetic rubbers, tires, styrene-butadiene, styrene-acrylonitrile, styrene-isoprene, styrene-maleic anhydride, ethylene vinyl acetate, nylon 12 / 6 / 66, filled polymers, polymer composites, plastic alloys, other polymeric materials, and polymers or plastics dissolved in solvents (even those obtained as waste or discarded materials from polymer or plastic manufacturing processes), post-consumer recycled polymeric materials, materials separated from waste streams such as municipal solid waste, and polymers produced by polymerization of monomers such as dienes, olefins, styrenes, acrylates, acrylonitrile, methacrylates, methacrylonitrile, diacids and diols, lactones, diacids and diamines, lactams, vinyl esters, block copolymers thereof, and alloys thereof, thermosetting polymers such as epoxy resins, phenolic resins, melamine resins, alkyd resins, vinyl ester resins, unsaturated polyester resins, crosslinked polyurethanes, polyisocyanurates, and crosslinked elastomers including, but not limited to, polyisoprene, polybutadiene, styrene-butadiene, styrene-isoprene, or any combination thereof.The present invention includes subcombinations of these materials as needed or available from a particular location, and the invention can be described as including one or any combination of these materials.

[0026] The plastic feed in FIG. 1 includes waste plastics that have been optionally pretreated to make them suitable for feeding into an extruder. The plastic mixture can be introduced into an optional feed system (not shown) that prepares the plastic mixture for introduction into the process by, for example, removing undesirable feed materials such as metals, minerals, and halogenated materials; sizing the materials to a desired size range; washing to remove contaminants; or some combination thereof. The steps of removing undesirable feed materials and sizing can be performed in any order, i.e., one step can be performed first and the other step can be performed second. Removal of undesirable materials can include either manual selection of materials or automated separation of undesirable materials, or both. In some examples, the separation step can include mechanical separation, settling / flotation, air screening, or other known separation processes, preferably in an automated manner. In some examples, the particle size of the solid polymer feed composition can be reduced in a size reduction system before sending the feed to the extruder. In some embodiments, the average diameter of the reduced size feed composition exiting the size reduction system comprises about 50% or less, about 25% or less, about 10% or less, about 5% or less, or about 2% or less of the mass average diameter of the feed composition fed to the size reduction system. The feed mixture can include a plastic mixture in which at least 85%, at least 90%, or at least 95% by mass of the particles pass through a 0.25 inch (0.6 cm), 0.5 inch (1.2 cm), 1.0 inch (2.5 cm), 1.5 inch (3.7 cm), 2 inch (5.0 cm), or 4 inch (10.0 cm) screen. The average diameter (size) can be measured by sieving through a mesh (screen) or a series of meshes. Larger particle feed materials may be easier to transport and less difficult to process than smaller particle feed materials. On the other hand, in some cases, it may be advantageous to feed smaller particles to a process. The use of a size reduction system allows for the transport of large particle feed between the source and the process while simultaneously allowing for the feeding of small particles to the process.

[0027] The plastic mixture, from which undesirable materials have been removed, can be sent to an optional washing process where the plastic mixture is cleaned, for example, by treating it with a washing solution to remove unwanted materials such as dirt, labels, coatings, etc., to produce a washed plastic mixture and a used washing solution. Optionally, the plastic mixture can be heated sufficiently to melt the materials and produce a molten mixture of plastics, which can optionally be passed through a screen or other filtering device to remove entrained solids.

[0028] The plastic mixture is fed into the extruder as a mass of small particles, as a molten mass, or some combination thereof, depending on pre-processing. The extruder is equipped with an inlet port for introducing the plastic mixture and an outlet port for sending the molten plastic to subsequent processing. The extruder is optionally equipped with one or more vapor outlet ports, allowing vapors entrained or generated within the extruder to escape the system and be processed separately from the molten plastic mixture. In the extruder, the mixture is compressed and heated to a temperature sufficient to decompose the plastic into a product mixture. The product mixture includes light components, such as HCl, in a vapor phase, heavier components in a molten liquid phase, or a combination of solid and liquid phases. The extruder may optionally be equipped with a gas inlet port through which gas is introduced, and the gas exits along with the generated vapor through one or more gas outlet ports. At least a portion of the vapor phase is discharged through the vapor outlet port for further processing. The molten liquid phase is compressed and pumped into a mixing vessel through the extruder's outlet port. The molten mixture can be pumped into a mixing vessel via a melt pump.

[0029] In the mixing vessel, the plastic mixture is heated to at least the same temperature as when it left the extruder, further decomposing the plastic and generating additional HCl. The molten plastic enters the mixing vessel at or near the top of the vessel by gravity and exits at or near the bottom. The plastic mixture can be extruded through the mixing vessel by the action of an extruder or by a melt pump. The flow of material through the mixing vessel approximates plug flow, i.e., there is little or no backmixing. The residence time of the material in the mixing vessel is at least 2, 5, 10, 20, 30, 40, 50, 60, or 70 minutes, or 2 to 150, 2 to 10, 10 to 120, 20 to 90, or 40 to 80 minutes. Optionally, the mixing vessel can include a gas vent to allow any HCl or other light gases generated within the vessel to separate and exit the vessel.

[0030] The residence time of the material in the devolatilizing vessel(s) is at least 2, 5, 10, 20, 30, 40, 50, 60, or 70 minutes, or 2 to 150, 2 to 10, 10 to 120, 20 to 90, or 40 to 80 minutes. The residence time of the molten plastic in the devolatilizing vessel(s) is sufficient to generate sufficient HCl from the plastic mixture, and the temperature is low enough so that little organic chloride is formed, and the resulting Cl concentration in the remaining molten mixture is less than 10%, 5%, 1%, 0.5%, 0.1%, 0.05%, 0.01%, 0.005%, or 0.001%, or a Cl concentration of 0.0001% to 1%, of the Cl concentration of the feed mixture introduced to the extruder. The molten dechlorinated plastic mixture exiting the devolatilization vessel(s) may contain less than 500, less than 200, less than 100, less than 50, less than 20, less than 10 or 5, less than 2 or less than 1, or 0.01 to 100, 0.02 to 50, 0.05 to 20, 0.1 to 10, or 0.1 to 5 ppm chlorine by weight. The devolatilization vessel(s) contain gas vent(s) that allow any HCl or other light gases produced in the devolatilization to separate and exit the vessel.

[0031] Optionally, the molten plastic mixture exiting the first devolatilization vessel can be sent to a second devolatilization vessel, where additional Cl-containing material can be evolved. The second devolatilization vessel can be the same type as the first devolatilization vessel or a different type. Removal of evolved vapors from the plastic melt can be accomplished by a vent located at or near the top of either the first or second devolatilization vessel, or both, through which evolved gases, including HCl, can escape. The molten plastic mixture recovered from the final devolatilization vessel can contain less than 500, less than 200, less than 100, less than 50, less than 20, less than 10, less than 5, less than 2, or less than 1, or 0.01 to 100, 0.02 to 50, 0.05 to 20, 0.1 to 10, or 0.1 to 5 ppm chlorine by weight.

[0032] An example of a static mixing vessel is shown schematically in Figure 2. In Figure 2, the vessel is cylindrical with an internal fixed (non-moving) structure that mixes the materials as they flow down through the vessel. The fixed structure can be a baffle, or a sphere with or without passages therein, or a molded article such as a Berle saddle, packing ring, Raschig ring, sponge with multiple pores, screen, net, or other shaped structure or mixture of different structures that promotes fluid mixing. Preferably, the fixed structure within the mixing vessel is one that minimizes resistance to plug flow of the molten mixed plastic mixture while providing good mixing, such as an open net, screen, or baffle. The fixed structure can be metal or ceramic, or some combination thereof. Because plug flow is established within the mixing vessel, backmixing is minimized. Due to the long residence time within the mixing vessel, HCl is evolved. Rather than condensing to form a separate phase, the evolved gas is carried into the molten plastic and can be sent to a devolatilization vessel(s).

[0033] Either the mixing vessel or the devolatilization vessel may optionally include an inlet port for introducing a gas at or near the bottom of the vessel, and a gas outlet port located at or near the top of the vessel. A sweep gas may be introduced into the vessel to carry away evolved vapors containing HCl, thereby reducing the opportunity for the HCl to react with organic species to form chlorine-containing hydrocarbon species.

[0034] Static mixers offer many advantages over agitated mixing, such as in a CSTR. Agitated mixers require a significant amount of energy to move agitating blades or other devices through a highly viscous plastic melt. Static mixers require much less energy than CSTRs. CSTRs also introduce a significant amount of backmixing. In fact, an "ideal" CSTR is "thoroughly mixed," so that the concentrations of materials within the CSTR are constant. Thus, a fresh feed containing a high concentration of polymer-bound Cl is dispersed throughout the mixture, maintaining a constant polymer-bound Cl content. In contrast, a static mixer with plug flow establishes a bound Cl concentration gradient from inlet to outlet due to the decomposition of materials that release HCl, resulting in less polymer-bound Cl and more "free" HCl in the mixture. Thus, the outlet mixture contains much less plastic-bound Cl, with the remainder present as HCl vapor entering the mixture, which can be easily released in the devolatilization vessel.

[0035] One embodiment of a devolatilizer vessel useful in this process is shown schematically in Figure 3. In this embodiment, the devolatilizer vessel includes paddles that promote condensation of the entering gases to form a separate vapor phase above the molten liquid phase, allowing for the removal of HCl. The mixed molten plastic enters at or near the top of the devolatilizer vessel and exits at or near the bottom of the vessel.

[0036] The devolatilization vessel can overcome the problem of high viscosity of the plastic mixture by operating at a higher temperature than the mixing vessel so that the viscosity of the plastic mixture is significantly reduced.

[0037] The extruder of the present invention includes an inlet port and an outlet port, and the temperature at or near the inlet port can optionally be 20°C to 200°C, e.g., 20°C to 100°C or 20°C to 50°C, and the temperature range at the hot outlet port can be 200°C to 400°C, e.g., 225°C to 350°C or 250°C to 300°C. Within the extruder, the feed mixture is preferably heated to a temperature of at least 200°C but not more than 400°C. The extruder can include a single-screw extruder, a twin-screw extruder, an auger reactor, or a similar device. Preferably, a gas selected from air, nitrogen, CO2, steam, helium, argon, or some combination thereof is fed to the extruder. Optionally, the extruder includes multiple zones separated so that migration of the vapor phase from an earlier zone to a later zone is inhibited, each zone having one or more gas outlet ports. The residence time of the feed mixture in the extruder is preferably at least 1, 2, 4, 10, 20, or 30 minutes, or from 1 to 60 or from 2 to 30 minutes. Optionally, the pressure in the extruder is at least 1 bar, at least 3 bar, at least 4 bar, from 1 to 20 bar, from 1 to 10 bar, or from 3 to 8 bar, preferably from 4 to 6 bar. Preferably, the pressure in the extruder is higher than the pressure in any mixing or devolatilization vessel(s).

[0038] Preferably, the extruder is in fluid communication with the mixing vessel and one or more devolatilization vessels, and the molten plastic mixture exiting the extruder enters the mixing vessel at or near the top of the vessel. The temperature of the plastic mixture in the mixing vessel can optionally be raised to at least 200°C, 225°C, or 250°C, or from 150°C to 350°C, or from 200°C to 300°C. Preferably, a gas comprising a material selected from air, nitrogen, CO2, steam, helium, argon, or some combination thereof is supplied at or near the bottom of the mixing vessel or devolatilization vessel, and steam is exhausted at or near the top of the vessel.

[0039] The molten plastic mixture exits the mixing vessel and is preferably passed through one or more devolatilizing vessels. The devolatilizing vessel may include two or more devolatilizing vessels in series. Optionally, the molten plastic mixture passes downward through either the mixing vessel or the devolatilizing vessel, or a combination thereof. In some embodiments, the mixing vessel or the devolatilizing vessel, or both the mixing vessel and the devolatilizing vessel, include cylindrical vessel(s). If the mixing vessel is cylindrical, the vessel preferably includes a packing material, for example, a fixed structure such as a baffle, or a mixing element such as a sphere with or without passages therein, or a molded article such as a Berle saddle, or a packing ring, or a Raschig ring, or a sponge, net, or screen containing multiple pores, or any other structure, or packing material containing a mixture of different structures. Optionally, at least one devolatilizing vessel is a continuous stirred tank reactor. The average residence time of the condensed phase in the mixing vessel or the optional devolatilization vessel, or the combined total of these vessels, is at least 2, 5, 10, 20, 30, 40, 50, or 60 minutes, or 2 to 150, 10 to 120, 20 to 90, or 40 to 80 minutes. Optionally, at least a portion of the non-vapor products of the devolatilization vessel, or a portion of the gas remaining after removal of the desired products, or both, is combusted to provide energy for the pyrolysis process. Optionally, a solid co-reactant is provided to at least one devolatilization vessel. The co-reactant may include, for example, one or more materials selected from agricultural lime, calcium oxide, calcium hydroxide, magnesium oxide, magnesium hydroxide, limestone, or hydrotalcite, or some combination thereof. The solid material may be separated from the liquid phase of the devolatilization vessel by filtration. The hot vapor product produced in the mixing vessel or the optional devolatilization vessel(s), or both, may be discharged. Optionally, the hot vapor product produced in the mixing vessel or optional devolatilization vessel(s), or both, is passed through a solid or solution to remove or recover HCl.Optionally, the pressure in the mixing vessel or any devolatilization vessel, or both, is at least 0.1 bar, at least 0.3 bar, or at least 0.5 bar, or between 0.1 and 10 bar, between 0.1 and 5 bar, or between 0.5 and 2 bar, preferably between 0.5 and 1.5 bar. Preferably, the pressure in the mixing vessel is higher than the pressure in the devolatilization vessel(s).

[0040] Optionally, a melt flow pump can be used to facilitate flow from the extruder or from the mixing vessel or one or more devolatilization vessels. The melt flow pump can be configured with an extrusion die and cutter system that produces pellets nominally 2, 3, or 4 mm, or 1-5 or 2-4 mm in diameter, with the pellets having a length / diameter ratio of 2 or less, 1.7 or less, 1.5 or less, or 1.2 or 1-2, or 1.2-1.7. The control system can be configured to allow an initial residence time of the plastic in the devolatilization vessel to be achieved before starting the melt flow pump and pelletizing system.

[0041] Optionally, the molten plastic mixture exiting the mixing vessel is introduced into the devolatilization vessel as a spray of droplets above the level of the plastics in the devolatilization vessel. Optionally, the droplet size has an average diameter of 20 mm or less, or 15 mm or less, or 10 mm or less, or 5 mm or less, or 2 mm or less, or 1 mm or less. Preferably, the droplets are formed by passing the molten plastic mixture under pressure at a high flow rate through a nozzle with multiple exit ports. A stream of low-average molecular weight material can be added to the molten plastic mixture entering the mixing vessel to promote mixing in the mixing vessel and droplet formation at the inlet of the devolatilization vessel. Optionally, the low-molecular weight material is a recycle stream from the process and has an average molecular weight of 1000, 800, 500, 200, or 150 g / mol or less. Optionally, at least 50, or 70, or 80, or 90 wt. % of the low molecular weight material added to the mixture of plastics entering the mixing vessel has a boiling range of 350-500°C, 375-475°C, or 400-450°C.

[0042] Vapors exiting the extruder, mixing vessel, or devolatilizing vessel(s), or some combination thereof, can be passed through a solid or solution that reacts with HCl to trap chlorine in the solid or solution. Optionally, the vapors substantially freed of HCl can be added to a molten plastic mixture for further upgrading during a plastic upgrading process.

[0043] The methods of the present invention may be further characterized by one or any combination of the following features:

[0044] supplies feeding a feed mixture containing a plastic containing at least 100 ppm by weight of chlorine to an extruder, The feed mixture may be polyethylene, polypropylene, polyester, polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinyl dichloride (PVDC), poly(1,1,2,2 tetrafluoroethylene) (PTFE), fluorinated polymers, acrylonitrile-butadiene-styrene (ABS) copolymers, polyamides, polyurethanes, polyethers, polycarbonates, poly(oxides), poly(sulfides), polyarylates, polyetherketones, polyetherimides, polysulfones, polyurethanes, polyvinyl alcohols, and polymers produced by polymerization of monomers, e.g., dienes, olefins, styrenes, acetones, and the like. acrylates, acrylonitrile, methacrylates, methacrylonitrile, diacids and diols, lactones, diacids and diamines, lactams, vinyl esters, block copolymers thereof, and alloys thereof; thermosetting polymers such as epoxy resins, phenolic resins, melamine resins, alkyd resins, vinyl ester resins, unsaturated polyester resins, crosslinked polyurethanes, polyisocyanurates; and crosslinked elastomers including, but not limited to, polyisoprene, polybutadiene, styrene-butadiene, styrene-isoprene, ethylene-propylene-diene monomer polymers, and mixtures thereof.

[0045] the feed mixture comprises a waste plastic mixture selected from polyethylene terephthalate (PET), high density polyethylene (HDPE), polyvinyl chloride (PVC) or polyvinylidene (PVCD), low density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), or mixed resins, or combinations thereof;

[0046] The plastic feed stream is first heated to a molten state and filtered to remove solids.

[0047] the feed stream comprises a polymer containing bromine or glass fibers, or a combination thereof;

[0048] The feed stream comprises biomass, or wood waste, or food waste, or the organic component of municipal solid waste, or agricultural waste, or a combination thereof.

[0049] Extruder The extruder includes an inlet port and an outlet port;

[0050] the temperature at or near the inlet port may be between 20°C and 250°C, e.g., between 20°C and 100°C or between 20°C and 50°C, and at the hot outlet port the temperature range may be between 200°C and 400°C, e.g., between 225°C and 350°C or between 250°C and 300°C;

[0051] the feed mixture is heated to a temperature of at least 200°C but not more than 400°C to at least partially decompose the polymer in the extruder;

[0052] the residence time of the feed mixture in the extruder is at least 1, 2, 4, 10, 20, or 30 minutes, or from 1 to 60 minutes, or from 2 to 30 minutes;

[0053] The extruder is equipped with one or more gas outlet ports through which the generated HCl can be removed;

[0054] HCl may be removed from the extruder through one or more gas exit ports;

[0055] Gas can be fed into the extruder,

[0056] An additive gas selected from air, nitrogen, CO2, steam, helium or argon, or some combination thereof, may be fed to the extruder;

[0057] HCl and any added gases can exit the extruder through one or more gas exit ports;

[0058] The extruder may include a single screw extruder, a twin screw extruder, an auger reactor, a rotary kiln reactor, or a staged grate reactor, or some combination thereof;

[0059] the extruder comprises a plurality of zones separated so that migration of the vapor phase from an earlier zone to a later zone is inhibited, at least one zone being provided with one or more gas exit ports;

[0060] The extruder includes a compounding port,

[0061] The extruder includes multiple extruders operating in parallel;

[0062] One or more extruder exit ports are operated under vacuum.

[0063] mixing container the extruder is in fluid communication with one or more mixing or devolatilizing vessels;

[0064] The molten plastic mixture exits the extruder and enters the mixing vessel at or near the top of the vessel,

[0065] The mixing vessel is a plug flow vessel,

[0066] The temperature of the plastic mixture in the mixing vessel is raised to at least 250, 275, 300, 325, or 350°C,

[0067] An additive gas selected from air, nitrogen, CO2, steam, helium, argon, or some combination thereof is provided at or near the bottom of the mixing or devolatilizing vessel, and the vapor is vented;

[0068] The molten plastic mixture leaving the mixing vessel may be passed through one or more devolatilizing vessels;

[0069] The devolatilization vessel includes two or more devolatilization vessels in series;

[0070] The molten plastic mixture may be passed downwardly through a mixing vessel, or a first or second devolatilization vessel, or any combination thereof;

[0071] the mixing vessel or the devolatilizing vessel, or both, comprises a cylindrical vessel;

[0072] the mixing vessel or devolatilization vessel(s), or both, contain a fill material;

[0073] the mixing vessel or devolatilization vessel(s), or both, are equipped with baffles or mixing elements;

[0074] The mixing elements in the mixing vessel may comprise fixed structures such as spheres with or without passages therein, or moldings such as Berl saddles, packing rings, Raschig rings, sponges containing a large number of pores, nets, screens, or any other shaped structure or combination of different structures;

[0075] the mean residence time of the condensed phase in the mixing vessel is at least 2, 5, 10, 20, 30, 40, 50, or 60 minutes, or 2 to 150, 2 to 10, 10 to 120, 20 to 90, or 40 to 80 minutes;

[0076] the average residence time of the condensed phase in the mixing vessel, or in any devolatilization vessel(s), or in the mixing vessel and any devolatilization vessel(s) is at least 2, 5, 10, 20, 30, 40, 50, or 60 minutes, or between 2 and 150, 2 and 10, 10 and 120, 20 and 90, or 40 and 80 minutes;

[0077] The temperature of the plastic mixture is raised in the mixing vessel to at least 200°C, 225°C or 250°C, or 150°C to 350°C, 200°C to 300°C or 250°C to 300°C, and the condensed phase is passed into a devolatilizing vessel;

[0078] at least a portion of the non-vapor products of the devolatilization vessel, or a portion of the gas remaining after removal of the desired products, or both, is combusted to provide energy for heating one or more of the extruder, the mixer, and the devolatilization vessel;

[0079] separating at least a portion of the condensed phase exiting the mixing vessel into a solid fraction and a liquid fraction and recycling at least a portion of the solids or a portion of the liquid, or both, to the extruder;

[0080] A solid co-reactant is fed into the mixing vessel or optional devolatilization vessel;

[0081] the solid co-reactant provided to the mixing vessel or optional devolatilization vessel comprises one or more materials selected from agricultural lime, calcium oxide, calcium hydroxide, magnesium oxide, magnesium hydroxide, limestone, or hydrotalcite, or some combination thereof;

[0082] The solid material is separated from the liquid phase of the mixing vessel or any devolatilization vessel by filtration;

[0083] The hot vapor product produced in the mixing vessel and / or optional devolatilization vessel is vented;

[0084] Passing the hot vapor product produced in the mixing vessel and / or devolatilization vessel(s) through a solid or solution to remove HCl;

[0085] A plug flow of the plastic mixture is established in the mixing vessel or optional devolatilization vessel,

[0086] The molten plastic mixture is pumped from the extruder to the mixing vessel via a melt pump.

[0087] The molten plastic mixture is pumped from the mixing vessel to the devolatilization vessel via a melt pump.

[0088] the pressure in the extruder is at least 0.1 MPa (1 bar), at least 0.3 MPa (3 bar) or at least 0.4 MPa (4 bar), or 0.1 to 2.0 MPa (1 to 20 bar), 0.1 to 1.0 MPa (1 to 10 bar) or 0.3 to 0.8 MPa (3 to 8 bar), preferably 0.4 to 0.6 MPa (4 to 6 bar),

[0089] the pressure in the mixing vessel or in the optional devolatilization vessel, or in both, is at least 0.1 bar, at least 0.3 bar or at least 0.5 bar, or between 0.1 and 10 bar, between 0.1 and 5 bar or between 0.5 and 2 bar, preferably between 0.5 and 1.5 bar,

[0090] The pressure in the extruder is higher than the pressure in the devolatilization vessel(s),

[0091] The pressure in the mixing vessel is higher than the pressure in the devolatilization vessel(s);

[0092] one or more of the devolatilization vessel(s) is a continuous stirred tank reactor vessel (CSTR);

[0093] one or more of the continuous stirred tank vessel(s) comprises a paddle or blade, or rotor / stator mixer, or multi-shaft mixer, or double planetary mixer, or helical mixer, or multiple active mixers;

[0094] The residence time of the plastic mixture in the mixing vessel is longer than the residence time in the devolatilization vessel(s);

[0095] the temperature of the plastic mixture in the mixing vessel is equal to or lower than the temperature in the devolatilization vessel(s);

[0096] separating at least a portion of the condensed phase exiting the devolatilization vessel into a solid fraction and a liquid fraction and recycling at least a portion of the solids or a portion of the liquid, or both, to the extruder or mixing vessel;

[0097] The plastic mixture entering the devolatilization vessel is dispersed as droplets into the gas phase in the devolatilization vessel,

[0098] The plastic mixture entering the devolatilization vessel is dispersed by passing through a spray nozzle,

[0099] The molten plastic mixture leaving the mixing vessel is introduced into the devolatilization vessel as a spray of droplets above the level of the plastics in the devolatilization vessel;

[0100] The size of the plastic droplets dispersed in the devolatilization container is 20mm, 15mm, 10mm, 5mm, 2mm, 1mm, 0.5mm, or 0.2mm or less in average diameter;

[0101] The droplets are formed by forcing the molten plastic mixture under pressure at a high flow rate through a nozzle with multiple exit ports,

[0102] adding a stream of low molecular weight hydrocarbon material to the molten plastic mixture entering the mixing vessel to promote mixing within the mixing vessel and droplet formation at the inlet of the devolatilization vessel;

[0103] The low molecular weight material added to the plastic mixture is a recycled stream from the process and has an average molecular weight of 1000, 800, 500, 200, or 150 g / mol or less;

[0104] At least 50, 70, 80, or 90 wt. % of the low molecular weight materials added to the mixture of plastics entering the mixing vessel have a boiling range of 350-500°C, 375-475°C, or 400-450°C;

[0105] At least one devolatilization vessel is subjected to ultrasonic treatment to enhance vapor / liquid separation;

[0106] The dechlorinated plastic mixture leaving the devolatilization vessel(s) is sent to a plastic upgrading process,

[0107] The plastic upgrading process is pyrolysis, or catalytic cracking, or hydrocracking, or some combination of these.

[0108] the dechlorinated plastic recovered from the first or second devolatilization vessel contains less than 500, less than 200, less than 100, less than 50, less than 20, less than 10, less than 5, less than 2, or less than 1 ppm by weight of chlorine, or 0.01 to 100, 0.02 to 50, 0.05 to 20, 0.1 to 10, or 0.1 to 5 ppm by weight of chlorine;

[0109] - passing the plastic mixture recovered from the final devolatilization vessel through a melt flow pump and an extrusion die and cutter to produce pellets having a nominal diameter of 2, 3, or 4, or 1 to 5, or 2 to 4 mm, and the length / diameter ratio of the pellets is 2 or less, 1.7 or less, 1.5 or less, or 1.2 or 1 to 2, or 1.2 to 1.7;

[0110] The plastic mixture recovered from the final devolatilization vessel is sent to a thermal cracker, hydrocracker, catalytic cracker, or other thermal processing unit(s) where the plastics are broken down into low average molecular weight substances;

[0111] the plastic mixture recovered from the final devolatilization vessel is mixed with a petroleum stream and sent to a thermal cracker, hydrocracker, catalytic cracker, or other thermal processing unit(s) where the plastics are broken down into low average molecular weight materials;

[0112] Materials recovered from a cracker, hydrocracker, catalytic cracker, or other thermal processing vessel containing olefins or aromatics, or some combination thereof;

[0113] ·Materials recovered from crackers, hydrocrackers, catalytic crackers, or other thermal processing vessels contain naphtha or C1-C8 hydrocarbons, or some combination thereof.

Claims

1. 1. A process for removing chlorine from a mixture of plastics, comprising: feeding a mixture of plastics having a chlorine content of at least 100 ppm by weight into an extruder; heating the mixture in the extruder and releasing a gas comprising HCl from the molten mixture through at least one degassing port; passing the extruded plastic mixture from b) through a first plug flow hot mixing vessel; c) passing the molten mixture through a devolatilizing vessel; and recovering the molten plastic having reduced chlorine content from the devolatilization vessel.

2. 10. The process of claim 1, wherein the devolatilizing vessel is a first devolatilizing vessel and the process further comprises a second devolatilizing vessel.

3. 3. The process of claim 2, wherein the first devolatilization vessel and the second devolatilization vessel are separate zones within a single vessel.

4. 10. The process of claim 1, wherein the devolatilization vessel is a continuous stirred tank reactor (CSTR).

5. 3. The process of claim 2, wherein a purge gas is provided to the first or the second devolatilization vessel, or to both vessels.

6. 10. The process of claim 1, wherein molten plastic exiting the extruder is transferred to the mixing vessel via a melt pump.

7. 10. The process of claim 1, wherein a gas stream passes through the molten mixture in the extruder and exits through the degassing port(s).

8. 10. The process of claim 1, wherein the temperature in the extruder is 400°C or less.

9. 2. The process of claim 1, wherein the temperature in the mixing vessel is at least 200°C, 225°C, 250°C, 300°C, or 350°C, or 150°C to 350°C, 200°C to 350°C, or 250°C to 350°C.

10. 10. The process of claim 1, wherein the mixing vessel is a column equipped with static mixing internals.

11. 9. The process of claim 8, wherein the mixing vessel comprises plug flow through a baffle or mixing element.

12. 10. The process of claim 1, wherein the molten plastic from the extruder enters an upper portion of a column equipped with a device for dispersing the molten plastic.

13. 13. The process of claim 12, wherein the device for dispersing the molten plastic is a spray nozzle.

14. 14. The process of any of claims 10 to 13, wherein the molten plastic with reduced chlorine content exits the mixer at a point in the column below the top.

15. The process of any one of claims 8 to 14, wherein the plastic mixture in the mixing vessel has a residence time of at least 30 minutes.

16. 10. The process of claim 1, comprising dewatering the plastic mixture before feeding it to the extruder, the dewatering being performed to reduce the moisture content to less than 0.1% water by weight.

17. 17. The process of claim 16, wherein the dehydrating step comprises heating to 110-120°C for at least 10 minutes.

18. 10. The process of claim 1, wherein the extruder has multiple degassing ports.

19. The feed mixture may be any of a variety of polymers, including polyethylene, polypropylene, polyester, polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinyl dichloride (PVDC), poly(1,1,2,2 tetrafluoroethylene) (PTFE), fluorinated polymers, acrylonitrile-butadiene-styrene (ABS) copolymers, polyamides, polyurethanes, polyethers, polycarbonates, poly(oxides), poly(sulfides), polyarylates, polyetherketones, polyetherimides, polysulfones, polyurethanes, polyvinyl alcohols, and polymers produced by polymerization of monomers, such as dienes, olefins, styrenes, acrylates, 10. The process of claim 1, comprising a plastic selected from among acrylonitrile, methacrylates, methacrylonitrile, diacids and diols, lactones, diacids and diamines, lactams, vinyl esters, block copolymers thereof, and alloys thereof; thermosetting polymers such as epoxy resins, phenolic resins, melamine resins, alkyd resins, vinyl ester resins, unsaturated polyester resins, crosslinked polyurethanes, polyisocyanurates; and crosslinked elastomers including, but not limited to, polyisoprene, polybutadiene, styrene-butadiene, styrene-isoprene, ethylene-propylene-diene monomer polymers, and mixtures thereof.

20. 10. The process of claim 1, wherein the feed mixture comprises a waste plastic mixture selected from polyethylene terephthalate (PET), high density polyethylene (HDPE), polyvinyl chloride (PVC) or polyvinylidene (PVCD), low density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), or combinations thereof.

21. 10. The process of claim 1, wherein the plastic feed stream is first heated to a molten state and filtered to remove solids before being fed to the extruder.

22. 2. The process of claim 1, wherein the extruder comprises an inlet port and an outlet port, and the temperature within the extruder is from 20°C to 250°C, such as from 20°C to 100°C or from 20°C to 50°C, at the inlet port, and the temperature at the hot outlet port ranges from 200°C to 400°C, such as from 225°C to 350°C or from 250°C to 300°C.

23. 10. The process of claim 1, wherein the feed mixture is heated in the extruder to a temperature of at least 200°C but not more than 400°C to at least partially decompose the polymer in the extruder.

24. 10. The process of claim 1, wherein the residence time of the feed mixture in the extruder is at least 1, 2, 4, 10, 20, or 30 minutes, or from 1 to 60, or from 2 to 30 minutes.

25. 10. The process of claim 1, wherein the extruder is equipped with one or more gas outlet ports to remove generated HCl.

26. Air, nitrogen, CO ２ 10. The process of claim 1, wherein a gas selected from the group consisting of hydrogen, steam, helium, argon, or some combination thereof is supplied to the extruder.

27. 10. The process of claim 1, wherein the extruder comprises a single screw extruder, a twin screw extruder, an auger reactor, or a combination thereof.

28. 10. The process of claim 1, wherein the extruder is in fluid communication with one or more mixing vessels and devolatilizing vessels.

29. 30. The process of claim 1 or 28, wherein the molten plastic mixture exits the extruder and enters the mixing vessel at or near the top of the vessel.

30. 10. The process of claim 1, wherein the temperature of the plastic mixture in the first mixing vessel is increased to at least 250°C, 275°C, 300°C, 325°C, or at least 350°C.

31. Air, nitrogen, CO ２ 2. The process of claim 1, wherein a gas selected from argon, steam, helium, argon, or a combination thereof is supplied to or near the bottom of the mixing vessel or the devolatilization vessel, or both, and the steam is exhausted.

32. 10. The process of claim 1, wherein the molten plastic mixture exiting the first mixing vessel is pumped to a devolatilization vessel by a melt pump.

33. 10. The process of claim 1, wherein the molten plastic mixture passes downwardly through the mixing vessel or the devolatilizing vessel, or both.

34. 10. The process of claim 1, wherein the mixing vessel or the devolatilizing vessel, or both, comprise a cylindrical vessel.

35. The process of claim 1 , wherein the mixing vessel contains a filler material.

36. 10. The process of claim 1, wherein the mixing vessel comprises a plug flow or mixing element.

37. 37. The process of claim 36, wherein the mixing element comprises a stationary structure.

38. 38. The process of claim 37, wherein the immobilization structure comprises a sphere, a Berle saddle, a packing ring, a Raschig ring, a sponge, or a screen, with or without a passage therethrough, or a combination thereof.

39. 2. The process of claim 1, wherein the average residence time of the condensed phase in the mixing vessel or the devolatilizing vessel, or the combined total of these vessels, is at least 2, 5, 10, 20, 30, 40, 50, or 60 minutes, or from 2 to 150, from 2 to 10, from 10 to 120, from 20 to 90, or from 40 to 80 minutes.

40. 10. The process of claim 1, wherein at least a portion of the non-vapor products of the devolatilizer vessel, or a portion of the gas remaining after removal of desired products, or both, is combusted to provide energy to heat one or more of the extruder, the mixer, and the devolatilizer vessel.

41. 10. The process of claim 1, wherein a solid co-reactant is provided to the devolatilization vessel.

42. 42. The process of claim 41 , wherein the solid co-reactant provided to the devolatilization vessel comprises one or more materials selected from agricultural lime, calcium oxide, calcium hydroxide, magnesium oxide, magnesium hydroxide, limestone, or hydrotalcite, or combinations thereof.

43. 43. The process of claim 41 or 42, wherein solid material is separated from the liquid phase of the first or second, or both, devolatilization vessels by filtration.

44. 10. The process of claim 1, wherein the hot vapor product produced in the mixing vessel, or the first or second devolatilization vessel, or any combination thereof, is vented.

45. 10. The process of claim 1, wherein the hot vapor product produced in the extruder, the mixing vessel, or the first or second devolatilizing vessel, or any combination thereof, is passed through a solid or solution to remove HCl.

46. 2. The process of claim 1, wherein the pressure in the extruder is at least 1 bar, at least 3 bar or at least 4 bar, or from 1 to 20 bar, from 1 to 10 bar or from 3 to 8 bar, preferably from 4 to 6 bar.

47. 3. A process according to claim 1 or 2, wherein the pressure in the first or second devolatilising vessel, or both, is at least 0.1 bar, at least 0.3 bar or at least 0.5 bar, or from 0.1 to 10 bar, from 0.1 to 5 bar or from 0.5 to 2 bar, preferably from 0.5 to 1.5 bar.

48. 10. The process of claim 1, wherein at least one devolatilization vessel is a continuous stirred tank reactor (CSTR).

49. 49. The process of claim 48, wherein one or more of the continuous stirred tank vessel(s) comprises a paddle or blade, or rotor / stator mixer, a multi-shaft mixer, or a double planetary mixer, or a helical mixer, or multiple active mixers.

50. 10. The process of claim 1, wherein the residence time of the plastic mixture in the first mixing vessel is greater than the residence time in the devolatilization vessel.

51. 10. The process of claim 1, wherein the temperature of the plastic mixture in the first mixing vessel is lower than the temperature in the devolatilization vessel(s).

52. 10. The process of claim 1, wherein the dechlorinated plastic mixture exiting the final devolatilization vessel is sent to a plastic upgrading process.

53. 53. The process of claim 52, wherein the plastic upgrading process is pyrolysis, or catalytic cracking, or hydrocracking, or some combination thereof.

54. 54. The process of claim 53, wherein the materials recovered from the cracker, hydrocracker, catalytic cracker, or other thermal treatment vessel comprise olefins or aromatics, or some combination thereof.

55. 55. The process of claim 53 or 54, wherein the material recovered from the cracker, hydrocracker, catalytic cracker, or other thermal treatment vessel comprises naphtha or C1 to C8 hydrocarbons, or some combination thereof.

56. 2. The process of claim 1, wherein the dechlorinated plastic recovered from the devolatilization vessel contains less than 500, less than 200, less than 100, less than 50, less than 20, less than 10, less than 5, less than 2, or less than 1, or 0.01 to 100, 0.02 to 50, 0.05 to 20, 0.1 to 10, or 0.1 to 5 ppm by weight of chlorine.

57. 10. The process of claim 1, wherein the plastic mixture recovered from the devolatilization vessel(s) is passed via a melt flow pump through an extrusion die and cutter to produce pellets having a nominal diameter of 2, 3, or 4, or 1 to 5, or 2 to 4 mm, and the length / diameter ratio of the pellets is 2 or less, 1.7 or less, 1.5 or less, or 1.2 or less, or 1 to 2, or 1.2 to 1.

7.

58. 10. The process of claim 1, wherein the feed stream comprises a polymer containing bromine or glass fibers, or some combination thereof.

59. 10. The process of claim 1, wherein the feed stream also includes biomass, or wood waste, or food waste, or the organic component of municipal solid waste, or agricultural waste, or some combination thereof.

60. The process of claim 1 , wherein the extruder comprises a compounding port.

61. The process of claim 1 , wherein the extruder comprises multiple extruders operating in parallel.

62. 10. The process of claim 1, wherein the one or more extruder exit ports are operated under vacuum.

63. 10. The process of claim 1, wherein the plastic mixture entering the devolatilization vessel is dispersed as droplets in a gas phase within the devolatilization vessel.

64. 64. The process of claim 63, wherein the molten plastic mixture exiting the mixing vessel is introduced into the devolatilization vessel as a spray of droplets above the level of plastics in the devolatilization vessel.

65. 65. The process of claim 63 or 64, wherein the droplets are formed by forcing the molten plastic mixture under pressure at a high flow rate through a nozzle having multiple exit ports.

66. 66. The process of claims 64-65, wherein the droplet size of the plastic dispersed in the devolatilization vessel has an average diameter of 20 mm, 15 mm, 10 mm, 5 mm, 2 mm, 1 mm, 0.5 mm, or 0.2 mm or less.

67. 10. The process of claim 1, wherein a stream of low average molecular weight hydrocarbon material is added to the molten plastic mixture entering the mixing vessel.

68. 66. The process of claim 65, wherein the low molecular weight material added to the plastic mixture is a recycle stream from a process and the weight average molecular weight is less than or equal to 1000, 800, 500, 200, or 150 g / mol.

69. 69. The process of claim 67 or 68, wherein at least 50, 70, 80, or 90 wt. % of the low molecular weight material added to the mixture of plastics entering the mixing vessel has a boiling range of 350 to 500°C, 375 to 475°C, or 400 to 450°C.

70. 10. The process of claim 1, wherein at least one devolatilization vessel is subjected to ultrasonic treatment to enhance vapor / liquid separation.

71. 10. The process of claim 1, wherein the pressure in the extruder is greater than the pressure in the mixing vessel and the devolatilizing vessel.

72. 10. The process of claim 1, wherein the pressure in the mixing vessel is greater than the pressure in the one or more devolatilizing vessels.

73. 10. The process of claim 1, wherein at least a portion of the condensed phase exiting the mixing vessel is separated into a solid fraction and a liquid fraction, and at least a portion of the solids, a portion of the liquid, or both, are recycled to the extruder.

74. 2. The process of claim 1, wherein at least a portion of the condensed phase exiting the devolatilizing vessel is separated into a solid fraction and a liquid fraction, and at least a portion of the solids, a portion of the liquid, or both, are recycled to the extruder or the mixing vessel.

Images