BACKGROUND

[0001] Waste plastic often contains quantities of very small plastic particles (microplastics or micronoodles). These plastic particles can be either manufactured to be millimeters or less in size, or they may be the result of larger plastic products breaking apart over time. Regardless, such small plastic particles pose environmental challenges. The small size allows the particles to easily become suspended in water streams, and they are not typically caught by filtering devices designed to catch larger debris. Thus, the small plastic particles are generally carried with water streams and end up aggregating with other plastic materials in larger bodies of water, or otherwise polluting the environment. Microplastics may even be consumed by aquatic life and be found in the meat of fish or other seafood caught from polluted bodies of water.

[0002] Plastic processing facilities may include several processes that generate microplastics or mix microplastics with water streams that are carried out of the facilities. Such processes may include size reduction, separations, and/or filtering processes. Thus, systems and processes for removing microplastics from process water streams in plastic processing facilities, or otherwise recovering and using the microplastics in a chemical recycling facility, are needed.

SUMMARY

[0003] In one aspect, the present technology concerns method of processing a mixed plastic waste comprising microplastics. Generally, the method comprises: (a) contacting an extractive fluid with water and the microplastics to form a multi-phase mixture; and (b) separating the multiphase mixture to form a microplastics-enriched organic phase and an aqueous phase. [0004] In one aspect, the present technology concerns a chemical recycling process. Generally, the process comprises: (a) processing mixed plastic waste comprising microplastics to produce a sorted plastic; (b) pyrolyzing at least a portion of the sorted plastic to produce at least one of a pyrolysis residue, a pyrolysis oil (pyoil) , and/or a pyrolysis gas (pygas); (c) cracking a hydrocarbon feed to produce a cracked product; (d) quenching at least a portion of the cracked product to produce a quenched product and a pyrolysis gasoline; (e) compressing at least a portion of the quenched product to produce a compressed product; and (f) separating at least a portion of the compressed product to produce a separated product. The processing of step (a) includes contacting the microplastics with an extractive fluid. At least a portion of the extractive fluid originates from at least one of: (i) the pyrolysis residue, (ii) the pyoil, (iii) the pyrolysis gasoline, and/or (iv) a hydrocarbon provided from outside of the process.

[0005] In one aspect, the present technology concerns a chemical recycling process. Generally, the process comprises: (a) contacting mixed plastic waste comprising microplastics with water to thereby form a microplastics-enriched water stream and a microplastics-depleted mixed plastic waste; and (b) pyrolyzing a feed comprising at least a portion of the microplastics from the microplastics-enriched water stream and at least a portion of the microplastics-depleted mixed plastic waste.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a block flow diagram illustrating the main steps of a process and facility for chemically recycling waste plastic and utilizing extractive fluid to recover microplastics according to embodiments of the present technology;

[0007] FIG. 2 is a block flow diagram illustrating a particular process of FIG. 1 including a plastic density separation process according to embodiments of the present technology; [0008] FIG. 3 is a block flow diagram illustrating a particular process of FIG. 1 including a caustic scrubber and utilizing spent caustic as an extractive fluid according to embodiments of the present technology; and

[0009] FIG. 4 is a block flow diagram illustrating a particular process of FIG. 1 including a caustic scrubber and utilizing spent caustic as an extractive fluid according to embodiments of the present technology.

DETAILED DESCRIPTION

[0010] We have discovered that microplastics can be recovered from waste plastic processing and used in downstream chemical recycling processes, rather than being lost to the environment or wastewater treatment outside of facility. More particularly, we have discovered that an extractive fluid may be used to agglomerate the microplastics in an organic phase and be separated from the aqueous streams. Consequently, the microplastics pose less of an environmental risk and chemical recycling yield can be increased.

[0011] FIG. 1 , below, depicts an exemplary chemical recycling facility 10 comprising a plastic processing facility 12, a pyrolysis facility 14, and a cracking facility (e.g., the cracker furnace 16, the quench system 18, the compression system 20, and the separator 22). As shown in FIG. 1 , the chemical recycling facility 10 may also contain one or more processes for recovering microplastics from plastic preprocessing wastewater. As noted above, the chemical recycling facility 10 and processes described herein are able to recover microplastics that would otherwise leave the facility with the wastewater. This recovery is generally achieved with the use of an extractive fluid, and the recovered microplastics may be fed to downstream chemical recycling processes. It should be understood that FIG. 1 depicts one exemplary embodiment of the present technology. Certain features depicted in FIG. 1 may be omitted and/or additional features described elsewhere herein may be added to the system depicted in FIG. 1 . The various process steps are described below in greater detail.

Overall Chemical Recycling Facility

[0012] Turning now to FIG. 1 , the main steps of a process for chemically recycling waste plastic in a chemical recycling facility 10 are shown.

Chemical recycling processes and facilities as described herein may be used to convert waste plastic to recycle content products or chemical intermediates used to form a variety of end use materials. The waste plastic fed to the chemical recycling facility/process can be mixed plastic waste (MPW), presorted waste plastic, and/or pre-processed waste plastic. As shown in FIG. 1 , the waste plastic feed stream may be derived from the waste plastic source, which may include a waste plastic preprocessing facility.

[0013] In an embodiment or in combination with any embodiment mentioned herein, the chemical recycling facility 10 may be a commercialscale facility capable of processing significant volumes of mixed plastic waste. As used herein, the term “commercial scale facility” refers to a facility having an average annual feed rate of at least 500 pounds per hour, averaged over one year.

[0014] In an embodiment or in combination with any embodiment mentioned herein, two or more of the facilities shown in FIG. 1 , such as the plastic preprocessing facility 12, the pyrolysis facility 14, and/or the cracking facility (e.g., the cracker furnace 16, the quench system 18, the compressor system 20, and the separator 22) may be co-located with one another. As used herein, the term “co-located” refers to facilities in which at least a portion of the process streams and/or supporting equipment or services are shared between the two facilities. When two or more of the facilities shown in FIG. 1 are co-located, the facilities may meet at least one of the following criteria (i) through (v): (i) the facilities share at least one non-residential utility service; (ii) the facilities share at least one service group; (iii) the facilities are owned and/or operated by parties that share at least one property boundary; (iv) the facilities are connected by at least one conduit configured to carry at least one process material (e.g., solid, liquid and/or gas fed to, used by, or generated in a facility) from one facility to another; and (v) the facilities are within 40, within 35, within 30, within 20, within 15, within 12, within 10, within 8, within 5, within 2, or within 1 mile of one another, measured from their geographical center. At least one, at least two, at least three, at least four, or all of the above statements (i) through (v) may be true.

[0015] Regarding (i), examples of suitable utility services include, but are not limited to, steam systems (co-generation and distribution systems), cooling water systems, heat transfer fluid systems, plant or instrument air systems, nitrogen systems, hydrogen systems, non-residential electrical generation and distribution, including distribution above 8000V, non- residential wastewater/sewer systems, storage facilities, transport lines, flare systems, and combinations thereof.

[0016] Regarding (ii), examples of service groups and facilities include, but are not limited to, emergency services personnel (fire and/or medical), a third- party vendor, a state or local government oversight group, and combinations thereof. Government oversight groups can include, for example, regulatory or environmental agencies, as well as municipal and taxation agencies at the city, county, and state level.

[0017] Regarding (iii), the boundary may be, for example, a fence line, a property line, a gate, or common boundaries with at least one boundary of a third-party owned land or facility.

[0018] Regarding (iv), the conduit may be a fluid conduit that carries a gas, a liquid, a solid/liquid mixture (e.g., slurry), a solid/gas mixture (e.g., pneumatic conveyance), a solid/liquid/gas mixture, or a solid (e.g., belt conveyance). In some cases, two units may share one or more conduits selected from the above list.

[0019] Turning again to FIG. 1 , a stream of waste plastic, which can be mixed plastic waste (MPW), may be introduced into the chemical recycling facility 10 from the waste plastic source. As used herein, the terms “waste plastic” and “plastic waste” refer to used, scrap, and/or discarded plastic materials, such as plastic materials typically sent to a landfill. The waste plastic stream fed to the chemical recycling facility 10 may include unprocessed or partially processed waste plastic. As used herein, the term “unprocessed waste plastic” means waste plastic that has not be subjected to any automated or mechanized sorting, washing, or comminuting. Examples of unprocessed waste plastic include waste plastic collected from household curbside plastic recycling bins or shared community plastic recycling containers. Partially processed waste plastics may originate from, for example, municipal recycling facilities (MRFs) or reclaimers. In certain embodiments, the waste plastic may comprise at least one of post-industrial (or pre-consumer) plastic and/or post-consumer plastic.

[0020] In an embodiment or in combination with any embodiment mentioned herein, the mixed waste plastic (MPW) includes at least two distinct types of plastic.

[0021] In an embodiment or in combination with any embodiment mentioned herein, all or a portion of the MPW in the waste plastic stream can originate from a municipal recycling facility (MRF).

[0022] In an embodiment or in combination with any embodiment mentioned herein, all or a portion of the MPW in the waste plastic stream can originate from a reclaimer facility.

[0023] Examples of suitable waste plastics can include, but are not limited to, polyolefins (PO), aromatic and aliphatic polyesters, polyvinyl chloride (PVC), polystyrene, cellulose esters, polytetrafluoroethylene, acrylobutadienestyrene (ABS), cellulosics, epoxides, polyamides, phenolic resins, polyacetal, polycarbonates, polyphenylene-based alloys, poly(methyl methacrylate), styrene-containing polymers, polyurethane, vinyl-based polymers, styrene acrylonitrile, and urea-containing polymers and melamines. [0024] Examples of specific polyolefins may include linear low-density polyethylene (LLDPE), low density polyethylene (LDPE), polymethylpentene, polybutene-1 , high density polyethylene (HDPE), atactic polypropylene, isotactic polypropylene, syndiotactic polypropylene, crosslinked polyethylene, amorphous polyolefins, and the copolymers of any one of the aforementioned polyolefins.

[0025] Examples of polyesters can include those having repeating aromatic or cyclic units such as those containing a repeating terephthalate, isophthalate, or naphthalate units such as PET, modified PET, and PEN, or those containing repeating furanate repeating units. As used herein, “PET” or “polyethylene terephthalate” refers to a homopolymer of polyethylene terephthalate, or to a polyethylene terephthalate modified with one or more acid and/or glycol modifiers and/or containing residues or moieties of other than ethylene glycol and terephthalic acid, such as isophthalic acid, 1 ,4- cyclohexanedicarboxylic acid, diethylene glycol, 2,2,4,4-tetramethyl-1 ,3- cyclobutanediol (TMCD), cyclohexanedimethanol (CHDM), propylene glycol, isosorbide, 1 ,4-butanediol, 1 ,3-propane diol, and/or neopentyl glycol (NPG). [0026] In an embodiment or in combination with any embodiment mentioned herein, the waste plastic stream comprises at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, at least 50, at least 55, at least 60, at least 65, at least 70, at least 75, at least 80, at least 85, at least 90, at least 95, or at least 99 weight percent of one or more polyolefins, based on the total weight of the stream. Alternatively, or in addition, the waste plastic stream comprises not more than 99.9, not more than 99, not more than 97, not more than 92, not more than 90, not more than 85, not more than 80, not more than 75, not more than 70, not more than 65, not more than 60, not more than 55, not more than 50, not more than 45, not more than 40, not more than 35, not more than 30, not more than 25, not more than 20, not more than 15, not more than 10, or not more than 5 weight percent of one or more polyolefins, based on the total weight of the stream.

[0027] In one embodiment or in combination with any of the mentioned embodiments, the waste plastic stream comprises not more than 20, not more than 15, not more than 12, not more than 10, not more than 8, not more than 6, not more than 5, not more than 4, not more than 3, not more than 2, or not more than 1 weight percent of polyesters, based on the total weight of the stream.

[0028] In one embodiment or in combination with any of the mentioned embodiments, the waste plastic stream comprises not more than 20, not more than 15, not more than 12, not more than 10, not more than 8, not more than 6, not more than 5, not more than 4, not more than 3, not more than 2, or not more than 1 weight percent of biowaste materials, based on the total weight of the stream. As used herein, the term “biowaste” refers to material derived from living organisms or of organic origin. Exemplary biowaste materials include, but are not limited to, cotton, wood, saw dust, food scraps, animals and animal parts, plants and plant parts, and manure.

[0029] In an embodiment or in combination with any embodiment mentioned herein, the waste plastic stream can include not more than 10, not more than 5, not more than 4, not more than 3, not more than 2, not more than 1 , not more than 0.75, or not more than 0.5 weight percent of polyvinyl chloride (PVC), based on the total weight of the stream.

[0030] In an embodiment or in combination with any embodiment mentioned herein, the waste plastic may comprise microplastics. As used herein, the term “microplastics” refers to a quantity of plastic particles that have a longest lateral dimension of less than 5 mm. The microplastics may include “micronoodles,” which are elongated or tubular plastic particles having a length less than 5 mm. The microplastics may comprise particles of any of the plastic materials described above. The microplastics may be present in the waste plastic fed to the chemical recycling facility 10 or may be produced during one or more waste plastic preprocessing steps, such as those described herein.

[0031] The general configuration and operation of each of the facilities that may be present in the chemical recycling facility 10 shown in FIG. 1 will now be described in further detail below, beginning with the preprocessing facility 12 of the waste plastic source. Plastic Preprocessing

[0032] As shown in FIG. 1 , unprocessed, partially processed, and/or processed waste plastic, such as mixed plastic waste (MPW), may first be introduced into the chemical recycling facility 10 via the waste plastic stream from the waste plastic source. As noted above, the waste plastic source may include a preprocessing facility 12 that can prepare the waste plastic feedstock for the downstream recycling processes. While in the preprocessing facility 12, the waste plastic feedstock may undergo one or more preprocessing steps to prepare it for chemical recycling. As used herein, the term “preprocessing facility” refers to a facility that includes all equipment, lines, and controls necessary to carry out the preprocessing of waste plastic. Preprocessing facilities as described herein may employ any suitable method for carrying out the preparation of waste plastic for chemical recycling, including but not limited to, size reduction (e.g., comminuting), particulating, washing, drying, filtering, and/or separation process(es).

[0033] In an embodiment or in combination with any embodiment mentioned herein, the waste plastic (e.g., MPW) may be provided in bales of unsorted or presorted plastic, or in other large, aggregated forms that may undergo an initial process in which they are broken apart. Plastic bales can be sent to a debaler machine that comprises, for example, one or more rotating shafts equipped with teeth or blades configured to break the bales apart, and in some instances shred, the plastics from which the bales are comprised. Additionally, or alternatively, the waste plastic feedstock may be subjected to a mechanical size reduction operation, such as grinding/granulating, shredding, guillotining, chopping, or other comminuting process to provide plastic particles having a reduced size. Such mechanical size reduction operations can include a size reduction step other than crushing, compacting, or forming plastic into bales. Additionally, or alternatively, the waste plastic feedstock may be sent to comminution or granulating equipment in which the plastic solids are ground, shredded, or otherwise reduced in size (e.g., into particles having a D90 particle size of less than 1 inch, less than % inch, or less than ¹ /2 inch). Any one or more of the above size reduction processes may directly or indirectly produce microplastics that are then present in the waste plastic feedstock.

[0034] In an embodiment or in combination with any embodiment mentioned herein, the preprocessing facility 12 of the waste plastic source may include at least one separation step or zone. The separation step or zone may be configured to separate the waste plastic stream into two or more streams enriched in certain types of plastics. Such separation is particularly advantageous when the waste plastic fed to the chemical recycling facility 10 is MPW. Any suitable type of separation device, system, or facility may be employed to separate the waste plastic into two or more streams enriched in certain types of plastics such as, for example, a PET-enriched stream and a PO-enriched stream. Examples of suitable types of separation include mechanical separation and density separation, which may include sink-float separation and/or centrifugal density separation. As used herein, the term “sink-float separation” refers to a density separation process where the separation of materials is primarily caused by floating or sinking in a selected liquid medium, while the term “centrifugal density separation” refers to a density separation process where the separation of materials is primarily caused by centrifugal forces.

[0035] As noted above, in one embodiment or in combination with any of the mentioned embodiments, the separating comprises at least one density separation stage. In one embodiment or in combination with any of the mentioned embodiments, the separating comprises at least two density separation stages (i.e., first and second density separation stages). The at least one density separation stage can comprise a sink-float density separation stage and/or a centrifugal force density separation stage. The sink-float density separation stage refers to a tank, vessel, or other appropriate container holding a liquid medium, such as water, that is capable of separating components of a feed mixture based on differences in density of the components. Components having a density greater than that of the liquid medium sink to the bottom of the tank, while components having a density less than that of the liquid medium float on the liquid surface. Various mechanical means can be used to recover the sunken components as a heavies or “high density” stream and to recover the floating components as a lights or “low density” stream.

[0036] In one embodiment or in combination with any of the mentioned embodiments, the liquid medium comprises water. Salts, saccharides, and/or other additives can be added to the liquid medium, for example to increase the density of the liquid medium and adjust the target separation density of the sink-float separation stage. In one embodiment or in combination with any of the mentioned embodiments, the liquid medium comprises a concentrated salt solution. In one or more such embodiments, the salt is sodium chloride. In one or more other embodiments, however, the salt is a non-halogenated salt, such as acetates, carbonates, citrates, nitrates, nitrites, phosphates, sulfates, and/or hydroxides. In one embodiment or in combination with any of the mentioned embodiments, the liquid medium comprises a concentrated salt solution comprising sodium bromide, sodium dihydrogen phosphate, sodium hydroxide, sodium iodide, sodium nitrate, sodium thiosulfate, potassium acetate, potassium bromide, potassium carbonate, potassium hydroxide, potassium iodide, calcium chloride, cesium chloride, iron chloride, strontium chloride, zinc chloride, manganese sulfate, zinc sulfate, and/or silver nitrate. In one embodiment or in combination with any of the mentioned embodiments, the salt is a caustic component. The concentrated salt solution may have a pH of greater than 7, greater than 8, greater than 9, or greater than 10. In one embodiment or in combination with any of the mentioned embodiments, the salt comprises sodium hydroxide, potassium hydroxide, and/or potassium carbonate. In one embodiment or in combination with any of the mentioned embodiments, the salt is potassium carbonate.

Advantageously, when the concentrated salt solution comprises potassium carbonate and/or other caustic component(s) (e.g., hydroxides, such as sodium hydroxide and/or potassium hydroxide), the use of a separate caustic component to control pathogens and odors can be avoided. Therefore, in one embodiment or in combination with any of the mentioned embodiments, no separate caustic component is introduced to the density separation stage(s). Additionally, when the concentrated salt solution comprises a caustic component and/or when a separate caustic component is added to the separation process(es) described herein, the caustic component is capable of killing pathogens (or inhibiting pathogen growth) and removing odor in-situ (e.g., in the density separation processes). This avoids the need for a separate unit operation to control pathogens and odors. Therefore, in one embodiment or in combination with any of the mentioned embodiments, the MPW is not subjected to a separate antimicrobial processing stage before being introduced into said to the density separation stage(s). As used herein, the term “antimicrobial processing stage” refers to a dedicated unit operation specifically for killing pathogens (or inhibiting pathogen growth) and/or removing odor from a feedstock.

[0037] In one embodiment or in combination with any of the mentioned embodiments, the liquid medium comprises a saccharide, such as sucrose. In one embodiment or in combination with any of the mentioned embodiments, the liquid medium comprises carbon tetrachloride, chloroform, dichlorobenzene, dimethyl sulfate, and/or trichloro ethylene. The particular components and concentrations of the liquid medium may be selected depending on the desired target separation density of the separation stage. [0038] In one embodiment or in combination with any of the mentioned embodiments, the liquid medium comprises an extractive fluid as described herein. Turning now to FIG. 2, a particular embodiment of the chemical recycling facility 10 of FIG. 1 is shown, which includes a density separation step within the mixed plastic waste (MPW) preprocessing facility 12. As shown, a water density adjustment system 24 may be used to adjust (e.g., increase) the density of the liquid medium used for one or more of the density separation stages within the MPW preprocessing facility 12. The extractive fluid may be introduced directly into the water density adjustment system 24, the extractive fluid may be introduced to the liquid medium between the density adjustment system 24 and the separation stage(s), and/or the extractive fluid may be introduced directly into the density separation stage (e.g., directly into the sink-float tank and/or centrifugal force separation system).

[0039] In an embodiment or in combination with any embodiment mentioned herein, the unprocessed or partially processed waste plastic may be washed or rinsed with water to remove inorganic, non-plastic solids such as dirt, glass, fillers and other non-plastic solid materials, to remove biological components such as bacteria and/or food, and/or to rinse any residual liquids or chemicals from the plastics, such as water density modifying agents used in the separations described herein. The washing 38 and/or rinsing steps may comprise contacting the waste plastic with water, or other cleaning liquids or solutions, such as solvents, caustic solutions, acid solutions, and the like, which removes a variety of non-plastic components and microplastics from the waste plastic (see, e.g., FIG. 4). The water 40 (or other liquids or solutions) containing the undesirable components can then be drained, filtered 42 to remove residual micrplastics, or collected for further treatment as described herein (see, e.g., FIG. 4). The washed plastics 44 may be subjected to drying 46 and the dried plastic stream 48 may then be further filtered 48 to remove additional impurities therefrom to form a filtered plastic stream 50 and/or introduced into the pyrolysis facility 14 (see, e.g., FIG. 4). [0040] Additionally, in an embodiment or in combination with any embodiment mentioned herein, the wash water and/or rinse water comprises microplastics removed from the waste plastic stream. Therefore, an extractive fluid may be mixed with the wash water and/or rinse water or other liquid before the wash and/or rinse step, during the wash and/or rinse step, and/or after the wash and/or rinse step, to recover the microplastics as described in greater detail below.

[0041] Referring again to FIG. 1 , the waste plastic stream may be introduced into one or more downstream processing facilities (or undergo one or more downstream processing steps) within the chemical recycling facility 10. In an embodiment or in combination with any embodiment mentioned herein, at least a portion of the waste plastic stream may be directly or indirectly introduced into a plastic liquification system within the waste plastic source or outside of it. Additional details of each step, as well as the general integration of each of these steps or facilities with one or more of the others according to one or more embodiments of the present technology are discussed in further detail below.

Microplastics Recovery

[0042] As explained above, microplastics may be present in the waste plastic feedstock and/or the plastic processing facilities 12 may include one or more processes that generate microplastics and/or otherwise mix the microplastics with water streams that are carried out of the facilities. The microplastics may be recovered from the waste plastic and/or water streams, which reduces the amount of microplastics being sent out of the chemical recycling facility 10, thereby reducing potential environmental impacts and increasing chemical recycling yield of the waste plastic. Accordingly, in an embodiment or in combination with any embodiment mentioned herein, the microplastics may be recovered in a method of processing a mixed plastic waste comprising microplastics.

[0043] In an embodiment or in combination with any embodiment mentioned herein, the methods may generally comprise contacting an extractive fluid with water and the microplastics to form a multi-phase mixture. As described in greater detail below, upon contacting the extractive fluid with the microplastics, the microplastics tend to adhere, adsorb, and/or otherwise agglomerate in the extractive fluid, thereby removing microplastics from the water and/or inhibiting microplastics from becoming suspended or entrained in the water stream. The resulting mixture of microplastics, water, and extractive fluid will therefore form multiple phases, with the microplastics adhered, adsorbed, and/or otherwise agglomerated in the extractive fluid, forming a microplastics-enriched organic phase, and the water forming a microplastics- depleted aqueous phase. The multi-phase mixture may then be separated, for example, to form a microplastics-enriched stream comprising predominantly the organic phase and a stream comprising predominantly the aqueous phase, which may be microplastics-depleted.

[0044] The microplastics recovery processes described herein generally rely on an extractive fluid to remove the microplastics from the waste plastic and/or water streams. As used herein, the term “extractive fluid” refers to a fluid that is immiscible in water at the processing temperature of the operation where the fluid is contacted with the water or microplastics, and capable of extracting microplastics from water. The extractive fluid may have a variety of compositions and be derived from a variety of sources, such as shown in FIG. 1 . For example, in an embodiment or in combination with any embodiment mentioned herein, at least a portion of the extractive fluid can originate from at least one of a pyrolysis wax (pyrolysis residue), a pyrolysis oil, and/or a pyrolysis gasoline, such as those produced in the pyrolysis process described herein, and/or from a hydrocarbon provided (e.g., purchased) from outside of the chemical recycling process or facility. Additionally, or alternatively, at least a portion of the extractive fluid may originate from, or otherwise comprise, at least a portion of a spent caustic stream, which may be produced in a caustic scrubber process. For example, the spent caustic stream may be produced from a caustic scrubber process within a cracker facility, such as described herein.

[0045] Regardless the source(s) of the extractive fluid, the extractive fluid should be capable of adhering, adsorbing, or otherwise agglomerating the microplastics, such that the microplastics have a greater affinity to the extractive fluid than to water. Without being bound by any particular theory, and with the understanding that the particular mechanism may vary depending on the particular extractive fluid used, it is believed that the microplastics may be generally adsorbed by organic (e.g., hydrocarbon) extractive fluid compounds, for example by hydrophobic interaction, and potentially by electrostatic interactions, hydrogen bonds, halogen bonds, and/or TT-TT interactions. Factors that may affect the ability for the extractive fluid to recover microplastics include, but are not limited to, the plastic composition, particle size, surface area, age, crystallinity, and polarity of the microplastics, and/or the extractive fluids particular hydrophobicity and chemical structure. Other factors may include process conditions, such as pH, temperature, and/or pressure. In an embodiment or in combination with any embodiment mentioned herein, the extractive fluid has a density less than water (specific gravity, SG, of 1) at the process conditions.

[0046] The particular composition of the extractive fluid can depend on the particular microplastic composition, concentrations, desired extraction rate, processing conditions, and/or cost/convenience factors. In an embodiment or in combination with any embodiment mentioned herein, the extractive fluid may comprise an organic compound selected from the group consisting of benzene, toluene, styrene, dicyclopentadiene (DCPD), and other hydrocarbons. In particular, the extractive fluid may comprise a hydrocarbon and may have at least 6, at least 8, or at least 10 carbon atoms and/or not more than 40 carbon atoms, not more than 30 carbon atoms, and/or not more than 20 carbon atoms. In an embodiment or in combination with any embodiment mentioned herein, the extractive fluid comprises a nonionic compound.

[0047] Referring again to FIGS. 1 and 2, the extractive fluid may be introduced into the process in a variety of locations. For example, in an embodiment or in combination with any embodiment mentioned herein, the extractive fluid may be added to water to form an extractive fluid and water mixture stream before introducing the water into a preprocessing and/or density adjustment step. Thus, the extractive fluid - water mixture stream may be produced before contacting the water or extractive fluid with the microplastics or microplastic-containing waste plastic materials. The extractive fluid - water mixture stream may be added to a waste plastic stream before, within, or after a preprocessing step. For example, the extractive fluid - water mixture may form at least a portion of the wash and/or rinse liquid in a wash and/or rinse step. Additionally, or alternatively, the extractive fluid - water mixture may form at least a portion of the liquid medium used in a density separation process.

[0048] In an embodiment or in combination with any embodiment mentioned herein, the extractive fluid may be added directly to a waste plastic preprocessing step (i.e, without being first mixed with water). For example, the extractive fluid may be used concurrently with a water stream to contact (wash and/or rinse) a waste plastic stream comprising microplastics, and/or the extractive fluid may be added directly to a density separation process (e.g., added to a sink-float tank).

[0049] In an embodiment or in combination with any embodiment mentioned herein, the extractive fluid may be introduced to a wastewater 28 (e.g., rinse water, drain water, etc.) stream downstream of a waste plastic preprocessing step. The wastewater stream may generally comprise microplastics suspended or otherwise entrained therein, which may be the result of the microplastics being washed away or otherwise separated from the waste plastic stream during a preprocessing step (e.g., rinsing, washing, density separation, etc.). The microplastics can then be recovered from the water stream by adding the extractive fluid, thereby extracting the microplastics into the extractive fluid of the organic phase.

[0050] As best shown in FIG. 1 , the microplastics may be separated and recovered from the extractive fluid - water mixture using a variety of processes including, but not limited to: (A) a skimming process (i.e., skimming the microplastics-enriched organic phase off the mixture); (B) a liquid-liquid extractive process; (C) a liquid-liquid extractive process with secondary separation; and/or (D) a froth floatation separation process. The recovered microplastics may then be used as a portion of the feedstock to downstream chemical recycling processes, such as the pyrolysis process described herein. The recovered microplastics may be fed to downstream processes with the extractive fluid (e.g., organic phase) or may be first separated from the organic phase. Particular embodiments of the microplastic separation and recovery processes are described in greater detail below. However, it should be understood that these descriptions illustrate exemplary processes only and should not be taken as limiting on the overall scope of the present technology. [0051] (A). Skimming - A skimming separation process generally comprises actively or passively causing a two-phase mixture to separate by gravity, whereby the less dense phase (typically the organic phase) rises to the top of the denser phase (typically the aqueous phase). The skimmer apparatus 26 may comprise a large hollow tank, whereby the phases gradually separate over time, and/or there may be internal coalescers to encourage droplets of the organic phase to agglomerate. Once the phases are sufficiently separated by gravity, the phase on top may be mechanically removed by overflow, suction, and/or mechanical removal. Any microplastics agglomerated in the organic phase will generally be skimmed off the top with the organic phase. However, as shown in FIG. 1 , trace organics may pass along with the water stream, depending on how well the phases separate from each other before skimming. Notably, lower density microplastics may float on water and thus would be expected to skim off the top, with or without the presence of the extractive fluid or organic liquid phase.

[0052] (B). Liquid-Liquid Extractive Process. A liquid-liquid extractive process is similar to a traditional liquid-liquid extraction process. However, rather than transferring a solute from one solvent to another (as in traditional liquid-liquid extraction), the interactions between the microplastics and extractive fluid effectively transfer the solid microplastics from the aqueous phase into the organic phase. The extracted microplastics can then be recovered in the organic phase and fed to downstream processes.

[0053] (C). Liquid-Liquid Extractive Process with Secondary Separation.

The organic phase obtained by process (B) described above may undergo further separation to recover the extractive fluid for reuse within the overall system. For example, the organic phase comprising microplastics may be subjected to filtration (e.g., membrane filtration, electrofiltration), mechanical agitation, adsorption, and the like, so as to remove the microplastics from the organic phase. The recovered microplastics may then be fed to downstream processes, and the extractive fluid can be recycled back upstream for reuse. [0054] (D). Froth Flotation. Froth flotation is particularly useful for separating small (micron-sized) particles and thus may be particularly useful for microplastics recovery. Generally, the mixture is treated with a frothing agent, which effectively separates the organic liquids/particles from polar liquids/particles, and the (forming a hydrophobic layer and a hydrophilic layer). The particles can then be brought to the surface by air bubbles and can be agglomerated in the organic phase (hydrophobic layer). Various surfactants or other collectors may be used to modify wettability of bubble surfaces to improve separation. The microplastics in the organic phase can then be removed and recovered using the same or similar mechanisms described above.

[0055] The microplastics recovery processes described above are generally effective at separating the mixture and producing at least a microplastics-enriched organic phase and an aqueous phase (predominantly water). In an embodiment or in combination with any embodiment mentioned herein, at least a portion of the microplastics-enriched organic phase is fed to a downstream chemical recycling process, such as a pyrolysis process. Additionally, or alternatively, at least a portion of the aqueous phase can be recycled to a plastic waste preprocessing step, such as a mixed plastic waste separation and/or washing process. However, with the microplastics removed from the wastewater stream, the aqueous phase may also be directed away from the facility, for example, to a wastewater treatment plant 30.

Pyrolysis

[0056] As shown in FIG. 1 , the chemical recycling facility 10 may comprise a pyrolysis facility 14. As used herein the term “pyrolysis” refers to the thermal decomposition of one or more organic materials at elevated temperatures in an inert (i.e. , substantially oxygen free) atmosphere. A “pyrolysis facility” is a facility that includes all equipment, lines, and controls necessary to carry out pyrolysis of waste plastic and feedstocks derived therefrom. The pyrolysis facility 14 can comprise the pyrolysis reactor and, optionally, the plastic liquification system and/or the waste plastic source. [0057] As depicted in FIG. 1 , the preprocessed (sorted) plastic stream may be introduced into a downstream pyrolysis reactor at a pyrolysis facility 14 so as to produce one or more pyrolysis effluent streams comprising a pyrolysis oil, a pyrolysis gas, and a pyrolysis residue (pyrolysis wax).

[0058] In an embodiment or in combination with any embodiment mentioned herein, the plastic stream to the pyrolysis facility 14 may be a polyolefin-enriched stream of waste plastic. The plastic stream introduced into the pyrolysis reactor can be in the form of liquified plastic (e.g., liquified, melted, plasticized, depolymerized, or combinations thereof), plastic pellets or particulates, or a slurry thereof.

[0059] As described above, at least a portion of the recovered microplastics may be used as a feedstock to the pyrolysis facility 14, either with the extractive fluid in the organic phase or separated from the organic phase. The microplastics may be combined with the primary plastic feedstock stream, before or after optional liquification, and the combined stream can be fed to the pyrolysis reactor. Thus, at least a portion of the microplastics that were separated into a microplastics-enriched water stream during preprocessing can be recombined with the microplastics-depleted plastic stream prior to pyrolysis, thereby increasing the overall yield of the chemical recycling process.

[0060] In general, the pyrolysis facility 14 may include an optional plastic liquification system, a pyrolysis reactor, and a separation system for the pyrolysis effluent, which can separate the pyrolysis effluent into a pyrolysis gas stream, a pyrolysis oil stream, and/or a pyrolysis residue (pyrolysis wax) stream.

[0061] While in the pyrolysis reactor, at least a portion of the feed may be subjected to a pyrolysis reaction that produces a pyrolysis effluent comprising a pyrolysis oil, a pyrolysis gas, and a pyrolysis residue. Generally, the pyrolysis effluent stream exiting the pyrolysis reactor can be in the form of pyrolysis vapors that comprise the pyrolysis gas and uncondensed pyrolysis oil. As used herein, “pyrolysis vapor” refers to the uncondensed pyrolysis effluent that comprises the majority of the pyrolysis oil and the pyrolysis gas present in the pyrolysis effluent.

[0062] Pyrolysis is a process that involves the chemical and thermal decomposition of the introduced feed. Although all pyrolysis processes may be generally characterized by a reaction environment that is substantially free of oxygen, pyrolysis processes may be further defined, for example, by the pyrolysis reaction temperature within the reactor, the residence time in the pyrolysis reactor, the reactor type, the pressure within the pyrolysis reactor, and the presence or absence of pyrolysis catalysts.

[0063] In an embodiment or in combination with any embodiment mentioned herein, the pyrolysis reactor can be, for example, a film reactor, a screw extruder, a tubular reactor, a tank, a stirred tank reactor, a riser reactor, a fixed bed reactor, a fluidized bed reactor, a rotary kiln, a vacuum reactor, a microwave reactor, or an autoclave. The pyrolysis reactor may comprise a film reactor, such as a falling film reactor or an up-flow film reactor.

[0064] In an embodiment or in combination with any embodiment mentioned herein, a lift gas and/or a feed gas may be used to introduce the feedstock into the pyrolysis reactor and/or facilitate various reactions within the pyrolysis reactor. For instance, the lift gas and/or the feed gas may comprise, consist essentially of, or consist of nitrogen, hydrogen, carbon dioxide, carbon monoxide, light hydrocarbons (such as methane, ethane) and hydrocarbon mixtures, and/or steam. The lift gas and/or feed gas may be added with the waste plastic stream prior to introduction into the pyrolysis reactor and/or may be added directly to the pyrolysis reactor. The lift gas and/or feed gas can include steam and/or a reducing gas such as hydrogen, carbon monoxide, and combinations thereof. [0065] Furthermore, the temperature in the pyrolysis reactor can be adjusted so as to facilitate the production of certain end products. In an embodiment or in combination with any embodiment mentioned herein, the pyrolysis temperature in the pyrolysis reactor can range from 325 to 1 ,100°C, 350 to 900°C, 350 to 700°C, 350 to 550°C, 350 to 475°C, 425 to 1 ,100°C, 425 to 800°C, 500 to 1 ,100°C, 500 to 800°C, 600 to 1 ,100°C, 600 to 800°C, 650 to 1 ,000°C, 700 to 1 ,000°C, or 650 to 800°C. The pyrolysis temperature in the pyrolysis reactor can be greater than 650°C.

[0066] In an embodiment or in combination with any embodiment mentioned herein, the residence times of the feedstocks within the pyrolysis reactor can be at least 0.1 , at least 0.2, at least 0.3, at least 0.5, at least 1 , at least 1 .2, at least 1 .3, at least 2, at least 3, or at least 4 seconds.

Alternatively, the residence times of the feedstocks within the pyrolysis reactor can be at least 1 , at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 20, at least 30, at least 45, at least 60, at least 75, or at least 90 minutes. Additionally, or alternatively, the residence times of the feedstocks within the pyrolysis reactor can be less than 6, less than 5, less than 4, less than 3, less than 2, less than 1 , or less than 0.5 hours. Furthermore, the residence times of the feedstocks within the pyrolysis reactor can be less than 100, less than 90, less than 80, less than 70, less than 60, less than 50, less than 40, less than 30, less than 20, less than 10, less than 9, less than 8, less than 7, less than 6, less than 5, less than 4, less than 3, less than 2, or less than 1 seconds. More particularly, the residence times of the feedstocks within the pyrolysis reactor can range from 0.1 to 10 seconds, 0.5 to 10 seconds, 30 minutes to 4 hours, or 30 minutes to 3 hours, or 1 hour to 3 hours, or 1 hour to 2 hours.

[0067] In an embodiment or in combination with any embodiment mentioned herein, the pressure within the pyrolysis reactor can be maintained at atmospheric pressure or within the range of 0.1 to 100 bar, or 0.1 to 60 bar, or 0.1 to 30 bar, or 0.1 to 10 bar, 0.2 to 1 .5 bar, or 0.3 to 1 .1 bar. As used herein, the term “bar” refers to gauge pressure, unless otherwise noted. [0068] In an embodiment or in combination with any embodiment mentioned herein, a pyrolysis catalyst may be introduced into the liquified plastic stream prior to introduction into the pyrolysis reactor and/or introduced directly into the pyrolysis reactor. The catalyst can be homogenous or heterogeneous and may include, for example, certain types of zeolites and other mesostructured catalysts. In some embodiments, the pyrolysis reaction may not be catalyzed (e.g., carried out in the absence of a pyrolysis catalyst), but may include a non-catalytic, heat- retaining inert additive, such as sand, in the reactor in order to facilitate the heat transfer. Such catalyst-free pyrolysis processes may be referred to as “thermal pyrolysis.”

[0069] In an embodiment or in combination with any embodiment mentioned herein, the pyrolysis reactor may be at least partially heated by a combustion system comprising an electric heater and/or a plurality of burners that combust a combustion fuel and a combustion air, as shown in FIG. 1. Furthermore, as depicted in FIG. 1 , this combustion system may produce a flue gas stream that can be removed from the pyrolysis reactor. The combustion fuel may comprise a conventional fossil fuel and/or a recycle content fuel, such as recycle content alkanes (e.g., r-methane) and/or recycle content hydrogen derived from the chemical recycling facility 10.

[0070] After exiting the pyrolysis reactor, the pyrolysis effluent may be separated into the pyrolysis oil stream and the pyrolysis gas stream in a separation system. Although not depicted in FIG. 1 , this separation system can include various types of equipment including, but not limited to a filter system, a multistage separator, a condensation zone, a distillation column, and/or a quench tower. While in the separation system, the pyrolysis effluent, such as the pyrolysis vapors, may be cooled to condense the pyrolysis oil fraction originally present in the pyrolysis effluent stream.

[0071] In an embodiment or in combination with any embodiment mentioned herein, the pyrolysis effluent or pyrolysis vapors from the pyrolysis reactor may comprise at least 1 , at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, at least 50, at least 55, at least 60, at least 65, at least 70, or at least 75 weight percent of the pyrolysis oil, based on the total weight of the pyrolysis effluent or pyrolysis vapors. Additionally, or alternatively, the pyrolysis effluent or pyrolysis vapors may comprise not more than 99, not more than 95, not more than 90, not more than 85, not more than 80, not more than 75, not more than 70, not more than 65, not more than 60, not more than 55, not more than 50, not more than 45, not more than 40, not more than 35, not more than 30, or not more than 25 weight percent of the pyrolysis oil, based on the total weight of the pyrolysis effluent or pyrolysis vapors. As discussed above, the pyrolysis oil may be in the form of uncondensed vapors in the pyrolysis effluent upon exiting the heated reactor; however, these vapors may be subsequently condensed into the resulting pyrolysis oil. The pyrolysis effluent or pyrolysis vapors may comprise in the range of 20 to 99 weight percent, 25 to 80 weight percent, 30 to 85 weight percent, 30 to 80 weight percent, 30 to 75 weight percent, 30 to 70 weight percent, or 30 to 65 weight percent of the pyrolysis oil, based on the total weight of the pyrolysis effluent or pyrolysis vapors. [0072] In an embodiment or in combination with any embodiment mentioned herein, the pyrolysis effluent or pyrolysis vapors from the pyrolysis reactor may comprise at least 1 , at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, at least 50, at least 55, at least 60, at least 65, at least 70, at least 75, or at least 80 weight percent of the pyrolysis gas, based on the total weight of the pyrolysis effluent or pyrolysis vapors. Additionally, or alternatively, the pyrolysis effluent or pyrolysis vapors may comprise not more than 99, not more than 95, not more than 90, not more than 85, not more than 80, not more than 75, not more than 70, not more than 65, not more than 60, not more than 55, not more than 50, or not more than 45 weight percent of the pyrolysis gas, based on the total weight of the pyrolysis effluent or pyrolysis vapors. The pyrolysis effluent may comprise 1 to 90 weight percent, 10 to 85 weight percent, 15 to 85 weight percent, 20 to 80 weight percent, 25 to 80 weight percent, 30 to 75 weight percent, or 35 to 75 weight percent of the pyrolysis gas, based on the total weight of the stream.

[0073] In an embodiment or in combination with any embodiment mentioned herein, the pyrolysis effluent or pyrolysis vapors from the pyrolysis reactor may comprise at least 0.5, at least 1 , at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, or at least 10 weight percent of the pyrolysis residue, based on the total weight of the pyrolysis effluent or pyrolysis vapors. Additionally, or alternatively, the pyrolysis effluent may comprise not more than 60, not more than 50, not more than 40, not more than 30, not more than 25, not more than 20, not more than 15, not more than 10, not more than 9, not more than 8, not more than 7, not more than 6, or not more than 5 weight percent of the pyrolysis residue, based on the total weight of the pyrolysis effluent or pyrolysis vapors. The pyrolysis effluent may comprise in the range of 0.1 to 25 weight percent, 1 to 15 weight percent, 1 to 8 weight percent, or 1 to 5 weight percent of the pyrolysis residue, based on the total weight of the pyrolysis effluent or pyrolysis vapors. This pyrolysis residue may be removed from the pyrolysis reactor (where it may form) and/or separated from the pyrolysis effluent in a downstream separator, such as the condenser.

[0074] The resulting pyrolysis oil stream and pyrolysis gas stream may be directly used in various downstream applications based on their formulations. The various characteristics and properties of the pyrolysis oil, pyrolysis gas, and pyrolysis residue are described below. It should be noted that, while all of the following characteristics and properties may be listed separately, it is envisioned that each of the following characteristics and/or properties of the pyrolysis gas, pyrolysis oil, and/or pyrolysis residue are not mutually exclusive and may be combined and present in any combination.

[0075] In an embodiment or in combination with any embodiment mentioned herein, the pyrolysis oil may predominantly comprise hydrocarbons having from 4 to 30 carbon atoms per molecule (e.g., C4 to C30 hydrocarbons). As used herein, the term “Cx” or “Cx hydrocarbon,” refers to a hydrocarbon compound including “x” total carbons per molecule, and encompasses all olefins, paraffins, aromatics, heterocyclic, and isomers having that number of carbon atoms. For example, each of normal, iso, and tert-butane and butene and butadiene molecules would fall under the general description “C4.” The pyrolysis oil may have a C4-C30 hydrocarbon content of at least 55, at least 60, at least 65, at least 70, at least 75, at least 80, at least 85, at least 90, or at least 95 weight percent based on the total weight of the pyrolysis oil stream.

[0076] In an embodiment or in combination with any embodiment mentioned herein, the pyrolysis oil can predominantly comprise C5 to C25 hydrocarbons, C5 to C22 hydrocarbons, or C5 to C20 hydrocarbons. For example, the pyrolysis oil may comprise at least 55, at least 60, at least 65, at least 70, at least 75, at least 80, at least 85, at least 90, or at least 95 weight percent of C5 to C25 hydrocarbons, C5 to C22 hydrocarbons, or C5 to C20 hydrocarbons, based on the total weight of the pyrolysis oil stream.

[0077] In an embodiment or in combination with any embodiment mentioned herein, the pyrolysis oil may have a mid-boiling point in the range of 75 to 250 °C, 90 to 225 °C, or 115 to 190 °C as measured according to ASTM D-2887. As used herein, “mid-boiling point” refers to the median boiling point temperature of the pyrolysis oil, where 50 percent by volume of the pyrolysis oil boils above the mid-boiling point and 50 percent by volume boils below the mid-boiling point.

[0078] In an embodiment or in combination with any embodiment mentioned herein, the boiling point range of the pyrolysis oil may be such that at least 90 percent of the pyrolysis oil boils off at a temperature of 250°C, of 280°C, of 290°C, of 300°C, or of 310°C, as measured according to ASTM D- 2887.

[0079] As noted above, the pyrolysis conditions, such as temperature, may be controlled so as to maximize the production of certain hydrocarbons and chemical compounds in the resulting pyrolysis gas and pyrolysis oil. [0080] T urning to the pyrolysis gas, the pyrolysis gas can have a methane content in the range of 1 to 50 weight percent, 5 to 50 weight percent, or 15 to 45 weight percent, based on the total weight of the pyrolysis gas stream.

[0081] In an embodiment or in combination with any embodiment mentioned herein, the pyrolysis gas can have a C3 and/or C4 hydrocarbon content (including all hydrocarbons having 3 or 4 carbon atoms per molecule) in the range of 10 to 90 weight percent, 25 to 90 weight percent, or 25 to 80 weight percent, based on the total weight of the pyrolysis gas stream.

[0082] In an embodiment or in combination with any embodiment mentioned herein, the pyrolysis gas can have a combined ethylene and propylene content of at least 25, at least 40, at least 50, at least 60, at least 70, or at least 75 weight percent, based on the total weight of the pyrolysis gas stream.

[0083] T urning to the pyrolysis residue (or pywax), in an embodiment or in combination with any embodiment mentioned herein, the pyrolysis residue comprises at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, at least 50, at least 55, at least 60, at least 65, at least 70, at least 75, at least 80, or at least 85 weight percent of C20+ hydrocarbons based on the total weight of the pyrolysis residue. As used herein, “C20+ hydrocarbon” refers to hydrocarbon compounds containing at least 20 total carbons per molecule, and encompasses all olefins, paraffins, and isomers having that number of carbon atoms.

[0084] As shown in FIG. 1 , at least a portion of the pyrolysis effluent, such as the pyrolysis gas stream, the pyrolysis oil steam, and/or the pyrolysis residue stream, may be routed to one or more other chemical processing facilities, including, for example, the cracking facility. In an embodiment or in combination with any embodiment mentioned herein, at least a portion of the pyrolysis effluent, such as the pyrolysis oil stream and/or the pyrolysis gas stream, may be routed to the cracker furnace 16 of the cracking facility. Cracking

[0085] In an embodiment or in combination with any embodiment mentioned herein, at least a portion of one or more streams from the pyrolysis facility 14, including the pyrolysis oil stream and/or the pyrolysis gas stream, may be introduced into a cracking facility. As used herein, the term “cracking” refers to breaking down complex organic molecules into simpler molecules by the breaking of carbon-carbon bonds. A “cracking facility” is a facility that includes all equipment, lines, and controls necessary to carry out cracking of a feedstock derived from waste plastic. A cracking facility can include one or more cracker furnaces 16, a quench system 18 for cooling the cracked products, a compression system 20, and a downstream separation zone 22 including equipment used to process the effluent of the cracker furnace(s). As used herein, the terms “cracker” and “cracking” are used interchangeably. [0086] In general, the cracker facility may include a cracker furnace 16, a quench system 18, a compression system 20, and a separation zone 22 downstream of the cracker furnace 16 for separating the furnace effluent into various end products, such as a recycle content hydrocarbons (r- hydrocarbons) stream. In an embodiment or in combination with any embodiment mentioned herein, at least a portion of the pyrolysis oil stream and/or the pyrolysis gas stream can be sent to the cracking facility. The pyrolysis oil stream may be introduced into an inlet of the cracker furnace 16, while the pyrolysis gas stream can be introduced into a location upstream or downstream of the furnace. The effluent from the cracker furnace 16 may be separated into various recycle content products in the downstream separator 22, as shown in FIG. 1 . When used, the pyrolysis oil stream and/or pyrolysis gas stream may optionally be combined with a stream of cracker feed to form the feed stream to the cracking facility.

[0087] In some embodiments, the cracker feed stream can include a hydrocarbon feed other than the pyrolysis gas and the pyrolysis oil stream in an amount of from 5 to 95 weight percent, 10 to 90 weight percent, or 15 to 85 weight percent, based on the total weight of the cracker feed. [0088] In an embodiment or in combination with any embodiment mentioned herein, the cracker facility may comprise a single cracking furnace, or it can have at least 2, or at least 3, or at least 4, or at least 5, or at least 6, or at least 7, or at least 8 or more cracking furnaces operated in parallel. Any one or each furnace(s) may be gas cracker, or a liquid cracker, or a split furnace.

[0089] The cracker feed stream, along with the pyrolysis oil stream and/or pyrolysis gas, may pass through the cracking furnace, wherein the hydrocarbon components therein are thermally cracked to form lighter hydrocarbons, including olefins such as ethylene, propylene, and/or butadiene. The residence time of the cracker stream in the furnace can be in the range of from 0.15 to 2 seconds, 0.20 to 1.75 seconds, or 0.25 to 1.5 seconds.

[0090] The temperature of the cracked olefin-containing effluent withdrawn from the furnace outlet can be in the range of from 730 to 900 °C, 750 to 875 °C, or 750 to 850 °C.

[0091] In an embodiment or in combination with any embodiment mentioned herein, the cracker furnace 16 may be at least partially heated by a combustion system comprising a plurality of burners that combust a combustion fuel and a combustion air. Furthermore, this combustion system may produce a flue gas stream that can be removed from the cracker furnace 16. The combustion fuel may comprise a conventional fossil fuel and/or a recycle content fuel, such as recycle content alkanes (e.g., r-methane) and/or recycle content hydrogen derived from the chemical recycling facility 10.

[0092] In an embodiment or in combination with any embodiment mentioned herein, when introduced into the cracker facility, the pyrolysis oil and/or gas streams may be introduced into the inlet of the cracker furnace 16, or all or a portion of the pyrolysis oil and/or gas streams may be introduced downstream of the furnace outlet, at a location upstream of or within the separation zone 22 of the cracker facility. When introduced into or upstream of the separation zone 22, the pyrolysis gas can be introduced upstream of the last stage of compression in the compressor 20, or prior to the inlet of at least one fractionation column in a fractionation section of the separator 22. [0093] Upon exiting the cracker furnace outlet, the olefin-containing effluent stream may be cooled rapidly (e.g., quenched) in the quench system 18 in order to prevent production of large amounts of undesirable by-products and to minimize fouling in downstream equipment. The quench system 18 can yield the quenched olefin-containing effluent stream and a waste quench fluid stream that may comprise water, residual quench oil, and/or residual steam. In an embodiment or in combination with any embodiment mentioned herein, the temperature of the olefin-containing effluent from the furnace can be reduced by 35 to 485°C, 35 to 375°C, or 90 to 550°C to a temperature of 350 to 760°C during the quench or cooling step. As shown in FIG. 1 , the waste quench fluid may comprise pyrolysis gasoline and/or may be used as an extractive fluid in the microplastic recovery process(es) described herein. [0094] In an embodiment or in combination with any embodiment mentioned herein, at least a portion of one or more of the above streams may be introduced into one or more of the facilities shown in FIG. 1 , while, in other embodiments, all or a portion of the streams withdrawn from the separation zone 22 of the cracking facility may be routed to further separation and/or storage, transportation, sale, and/or use.

Caustic Scrubber Process

[0095] Referring now to FIGS. 3 and 4, in an embodiment or in combination with any embodiment mentioned herein, the cracker facility may comprise a caustic scrubber process. The feedstock gas to the caustic scrubber will generally comprise an effluent stream from a cracker furnace 16 after compression.

[0096] The caustic scrubber system 32 may have a variety of designs and geometries, depending on factors such as gas flow rate and composition. In an embodiment or in combination with any embodiment mentioned herein, the caustic scrubber may be a three-stage scrubber, although the caustic scrubber can comprise two, three, four, five, or more stages. One or more of the stages may comprise packing material to increase the contact between the gas and liquid phases. In some embodiments, the caustic scrubber process operates at a temperature of 25 °C to 65 °C.

[0097] Generally, the feedstock gas is fed to the bottom stage of the caustic scrubber tower above any liquid accumulated at the scrubber bottoms. Fresh caustic solution can be fed directly to any caustic stage. As the gas flows upward within and between stages, the gas contacts the caustic solution flowing downward, thereby transferring certain gaseous components (e.g., carbon dioxide) to the liquid caustic solution. The caustic solution may comprise a dissolved caustic component selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium oxide, potassium carbonate, and combinations thereof. The top stage can be an optional water section, which can remove residual caustic or salts in the gas stream. Additionally, the top water feed can be diverted and used to dilute the fresh caustic feed as needed.

[0098] The caustic scrubber process generally removes carbon dioxide (CO2), sulfur (including sulfur-containing compounds, such as H ₂ S), and/or other undesirable components from the cracker effluent, and thereby produces a scrubbed gas stream and a spent caustic solution bottoms stream. In addition to residual caustic solution, the spent caustic stream may further comprise one or more of sodium carbonate, sodium bicarbonate, sodium sulfide, sodium polysulfide, and/or sodium bisulfide. The spent caustic stream (or at least a portion thereof) may then be used as at least a portion of the extractive fluid for microplastics recovery, as described herein. [0099] Referring to FIG. 3, in an embodiment or in combination with any embodiment mentioned herein, at least a portion of the spent caustic stream from the caustic scrubber process may be recycled back for use as an extractive fluid in a mixed plastic waste preprocessing step. For example, at least a portion of the spent caustic stream may contact the mixed plastic waste comprising microplastics, for example, by introducing at least a portion of the spent caustic stream to one or more of: (i) a mixed plastic waste preprocessing process; (ii) a water density adjustment process 24; (iii) a plastic density

Definitions

[0100] It should be understood that the following is not intended to be an exclusive list of defined terms. Other definitions may be provided in the foregoing description, such as, for example, when accompanying the use of a defined term in context.

[0101] As used herein, the terms “a,” “an,” and “the” mean one or more.

[0102] As used herein, the term “and/or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination, B and C in combination; or A, B, and C in combination.

[0103] As used herein, the phrase “at least a portion” includes at least a portion and up to and including the entire amount or time period.

[0104] As used herein, “aqueous” refers to a fluid containing at least five percent of molecular water by weight.

[0105] As used herein, the term “bottom” refers to the physical location of a structure that is below the other noted structures within an enclosed structure. For example, a “bottom” stream is a stream taken from a vessel at a position that is lower elevation-wise to other streams taken from the vessel, such as an “overhead” stream.

[0106] As used herein, the term “chemical recycling” refers to a waste plastic recycling process that includes a step of chemically converting waste plastic polymers into lower molecular weight polymers, oligomers, monomers, and/or non-polymeric molecules (e.g., hydrogen, carbon monoxide, methane, ethane, propane, ethylene, and propylene) that are useful by themselves and/or are useful as feedstocks to another chemical production process(es). [0107] As used herein, the term “chemical recycling facility” refers to a facility for producing a recycle content product via chemical recycling of waste plastic.

[0108] As used herein, the term “co-located” refers to the characteristic of at least two objects being situated on a common physical site, and/or within one mile of each other.

[0109] As used herein, the terms “comprising,” “comprises,” and “comprise” are open-ended transition terms used to transition from a subject recited before the term to one or more elements recited after the term, where the element or elements listed after the transition term are not necessarily the only elements that make up the subject.

[0110] As used herein, the term “cracking” refers to breaking down complex organic molecules into simpler molecules by the breaking of carboncarbon bonds.

[0111] As used herein, the term “depleted” refers to having a concentration (on a dry weight basis) of a specific component that is less than the concentration of that component in a reference material or stream.

[0112] As used herein, the term “directly derived” refers to having at least one physical component originating from waste plastic.

[0113] As used herein, the term “enriched” refers to having a concentration (on a dry weight basis) of a specific component that is greater than the concentration of that component in a reference material or stream.

[0114] As used herein, the term “extractive fluid” refers to a fluid that is immiscible in water at the processing temperature of the operation where the fluid is contacted with the water or microplastics, and capable of extracting microplastics from water.

[0115] As used herein, the term “fluid” may encompass a liquid, a gas, a supercritical fluid, or a combination thereof. [0116] As used herein, the term “halide” refers to a composition comprising a halogen atom bearing a negative charge (i.e., a halide ion).

[0117] As used herein, the term “halogen” or “halogens” refers to organic or inorganic compounds, ionic, or elemental species comprising at least one halogen atom.

[0118] As used herein, the terms “having,” “has,” and “have” have the same open-ended meaning as “comprising,” “comprises,” and “comprise” provided above.

[0119] As used herein, the terms “including,” “include,” and “included” have the same open-ended meaning as “comprising,” “comprises,” and “comprise” provided above.

[0120] As used herein, the term “indirectly derived” refers to having an assigned recycle content i) that is attributable to waste plastic, but ii) that is not based on having a physical component originating from waste plastic. [0121] As used herein, the term “isolated” refers to the characteristic of an object or objects being by itself or themselves and separate from other materials, in motion or static.

[0122] As used herein, the term “microplastics” refers to a quantity of plastic particles that have a longest lateral dimension of less than 5 mm. The microplastics may include “micronoodles,” which are elongated or tubular plastic particles having a length less than 5 mm.

[0123] As used herein, the terms “mixed plastic waste” and “MPW” refer to a mixture of at least two types of waste plastics including, but not limited to the following plastic types: polyethylene terephthalate (PET), one or more polyolefins (PO), and polyvinylchloride (PVC).

[0124] As used herein, “non-aqueous” refers to a fluid containing less than five percent of molecular water by weight.

[0125] As used herein, the term “overhead” refers to the physical location of a structure that is above a maximum elevation of quantity of particulate plastic solids within an enclosed structure. For example, an “overhead” stream is a stream taken from a vessel at a position that is higher elevationwise to other streams taken from the vessel, such as a “bottom” stream.

[0126] As used herein, the term “partially processed waste plastic” means waste plastic that has been subjected to at least on automated or mechanized sorting, washing, or comminuted step or process. Partially processed waste plastics may originate from, for example, municipal recycling facilities (MRFs) or reclaimers. When partially processed waste plastic is provided to the chemical recycling facility, one or more preprocessing steps may me skipped.

[0127] As used herein, the term “physical recycling” (also known as “mechanical recycling”) refers to a waste plastic recycling process that includes a step of melting waste plastic and forming the molten plastic into a new intermediate product (e.g., pellets or sheets) and/or a new end product (e.g., bottles). Generally, physical recycling does not substantially change the chemical structure of the plastic, although some degradation is possible.

[0128] As used herein, the term “plastic” may include any organic synthetic polymers that are solid at 25°C and 1 atmosphere of pressure.

[0129] As used herein, the term “predominantly” means more than 50 percent by weight. For example, a predominantly propane stream, composition, feedstock, or product is a stream, composition, feedstock, or product that contains more than 50 weight percent propane.

[0130] As used herein, the term “preprocessing” refers to preparing waste plastic for chemical recycling using one or more of the following steps: (i) comminuting, (ii) particulating, (iii) washing, (iv) drying, and/or (v) separating, or other processes described herein.

[0131] As used herein, the term “pyrolysis” refers to thermal decomposition of one or more organic materials at elevated temperatures in an inert (i.e., substantially oxygen free) atmosphere.

[0132] As used herein, the term “pyrolysis char” refers to a carbon- containing composition obtained from pyrolysis that is solid at 200°C and 1 atm. [0133] As used herein, the terms “pyrolysis gas” and “pygas” refer to a composition obtained from pyrolysis that is gaseous at 25°C at 1 atm.

[0134] As used herein, the term “pyrolysis heavy waxes” refers to C20+ hydrocarbons obtained from pyrolysis that are not pyrolysis char, pyrolysis gas, or pyrolysis oil.

[0135] As used herein, the terms “pyrolysis oil” or “pyoil” refers to a composition obtained from pyrolysis that is liquid at 25°C and 1 atm.

[0136] As used herein, the term “pyrolysis residue” refers to a composition obtained from pyrolysis that is not pyrolysis gas or pyrolysis oil and that comprises predominantly pyrolysis char and pyrolysis heavy waxes.

[0137] As used herein, the terms “recycle content” and “r-content” refer to being or comprising a composition that is directly and/or indirectly derived from waste plastic.

[0138] As used herein, the terms “r-pyrolysis gas” or “r-pygas” refer to being or comprising a pyrolysis gas that is directly and/or indirectly derived from waste plastic.

[0139] As used herein, the terms “r-pyrolysis oil” or “r-pyoil” refer to being or comprising a pyrolysis oil that is directly and/or indirectly derived from waste plastic.

[0140] As used herein, the term “residual” refers to a remaining quantity or amount of an identified product or component that remains from an original source containing the product or component. For example, a “residual pyrolysis oil” may refer to the remaining pyrolysis oil from an initial pyrolysis effluent after the majority of the pyrolysis oil has been previously removed therefrom.

[0141] As used herein, the terms “waste plastic” and “plastic waste” refer to used, scrap, and/or discarded plastic materials. The waste plastic fed to the chemical recycling facility may be unprocessed or partially processed. [0142] As used herein, the term “unprocessed waste plastic” means waste plastic that has not be subjected to any automated or mechanized sorting, washing, or comminuting. Examples of unprocessed waste plastic include waste plastic collected from household curbside plastic recycling bins or shared community plastic recycling containers.

[0143] As used herein, “downstream” means a target unit operation, vessel, or equipment that: a. is in fluid (liquid or gas) communication, or in piping communication, with an outlet stream from the radiant section of a cracker furnace, optionally through one or more intermediate unit operations, vessels, or equipment, or b. was in fluid (liquid or gas) communication, or in piping communication, with an outlet stream from the radiant section of a cracker furnace, optionally through one or more intermediate unit operations, vessels, or equipment, provided that the target unit operation, vessel, or equipment remains within the battery limits of the cracker facility (which includes the furnace and all associated downstream separation equipment).

CLAIMS NOT LIMITED TO DISCLOSED EMBODIMENTS

[0144] When a numerical sequence is indicated, it is to be understood that each number is modified the same as the first number or last number in the numerical sequence or in the sentence, e.g., each number is “at least,” or “up to” or “not more than” as the case may be; and each number is in an “or” relationship. For example, “at least 10, 20, 30, 40, 50, 75 wt.%...” means the same as “at least 10 wt.%, or at least 20 wt.%, or at least 30 wt.%, or at least 40 wt.%, or at least 50 wt.%, or at least 75 wt.%,” etc.; and “not more than 90 wt.%, 85, 70, 60...” means the same as “not more than 90 wt.%, or not more than 85 wt.%, or not more than 70 wt.%....” etc.; and “at least 1 %, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10% by weight...” means the same as “ at least 1 wt.%, or at least 2 wt.%, or at least 3 wt.% ...” etc.; and “at least 5, 10, 15, 20 and/or not more than 99, 95, 90 weight percent” means the same as “at least 5 wt.%, or at least 10 wt.%, or at least 15 wt.% or at least 20 wt.% and/or not more than 99 wt.%, or not more than 95 wt.%, or not more than 90 weight percent...” etc. [0145] The preferred forms of the invention described above are to be used as illustration only and should not be used in a limiting sense to interpret the scope of the present invention. Modifications to the exemplary embodiments, set forth above, could be readily made by those skilled in the art without departing from the spirit of the present invention.

[0146] The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as it pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.