Systems and methods for degradation of polymeric materials

Abstract

A system and associated method for decomposing plastic materials is provided. The system includes a body, a hopper, a conveying system, a drive system, and a UV light assembly. A related method includes feeding a polymer material to the hopper, feeding a solvent to the hopper, activating the drive system, and activating a UV light.

Description

[Technical Field]

[0001] The present disclosure relates generally to a reactor system for the decomposition of polymeric materials. Specifically, the present disclosure relates to a conveyorized reactor system adapted to decompose polymeric materials into terephthalic acid (TPA) and / or ethylene glycol and / or other monomers that form plastic materials. [Background technology]

[0002] US Patent No. 5,929,999 (incorporated herein by reference in its entirety) provides a method for alkaline hydrolysis of one or more plastic polymers into terephthalic acid (TPA) and / or ethylene glycol (EG) and / or other monomers that form one or more plastic polymers, the method comprising: a) contacting one or more plastic polymers with a metal oxide in solution in the presence of a base to provide a reaction mixture; b) stirring the reaction mixture under ultraviolet ("UV") light for a suitable period of time; c) recovering terephthalic acid, ethylene glycol and / or other monomers from the reaction mixture. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 173961 Summary of the Invention [Problem to be solved by the invention]

[0004] The method of the '661 patent can be practically difficult to carry out economically on a commercial scale using standard or readily available chemical processing equipment. Specifically, current reactors are not appropriately configured to carry out the method of the above cited reference.

[0005] Therefore, there is a need for an improved reaction vessel in which the reactions of the above cited references can be carried out more economically. [Means for solving the problem]

[0006] Disclosed herein, according to an embodiment, is a reactor vessel system for decomposing polymeric materials, the system including: a hopper for receiving input materials (the input materials including a polymer, a solvent, a metal oxide, and a base); a body extending along a first axis and having a first end and a second end, the first end being coupled to the hopper and capable of receiving the input material introduced into the hopper; a conveying system for conveying the input material along the body; a drive system for imparting motion to the conveying system; and an ultraviolet ("UV") light for exposing the input material within the body to ultraviolet light to decompose the input material.

[0007] According to some embodiments, the body is liquid-tight and the liquid is contained by the body. According to some embodiments, the polymer comprises any one of polylactic acid, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene isosorbide terephthalate, polyethylene furanoate, polyvinyl chloride, and polyvinylidene chloride, or a combination thereof.

[0008] According to some embodiments, a conveying system is disposed within the reactor system such that the conveying system can convey material introduced into the hopper from the hopper into the body. According to some embodiments, a conveying system is disposed within the reactor system such that the conveying system can convey material from a first end of the body to a second end of the body.

[0009] According to some embodiments, the conveying system comprises an Archimedes screw having a central shaft and configured to convey the input material along the body. According to some embodiments, a drive system is coupled to the Archimedes screw and configured to rotate the Archimedes screw about the central shaft of the Archimedes screw. According to some embodiments, the length of the Archimedes screw is between 1 meter and 10 meters.

[0010] Disclosed herein is a method of operating a reactor system, according to one embodiment. The method includes the steps of feeding a polymeric material to a hopper, feeding a solvent to the hopper, activating a drive system, and activating a UV light. According to some embodiments, the solvent includes ethanol. According to some embodiments, the method further includes feeding a metal oxide to the hopper. According to some embodiments, the method further includes feeding a base to the hopper. According to some embodiments, the material fed to the reactor has a pH greater than 7. According to some embodiments, the drive system is configured to rotate the conveying system at a speed greater than 30 revolutions per minute.

[0011] Other aspects and features will become apparent to those skilled in the art upon review of the following description of several exemplary embodiments. [Brief explanation of the drawings]

[0012] The drawings included herein are intended to illustrate various examples of the articles, methods and apparatus herein. [Figure 1] FIG. 1 is a perspective view of a screw conveyor type reaction vessel system according to an embodiment. [Figure 2] 2 is a partial perspective view of the screw conveyor reactor system of FIG. 1 according to an embodiment. [Figure 3]FIG. 3 is a perspective view showing an isolated Archimedes screw of the screw conveyor reactor system of FIGS. 1 and 2, according to an embodiment. [Figure 4] FIG. 4 is a cross-sectional front view of the screw conveyor reactor system of FIGS. 1-3 taken along section AA in FIG. 1, according to an embodiment. [Figure 5] FIG. 5 is a detailed perspective view of an ultraviolet light assembly of the screw conveyor reactor system of FIGS. 1-4, according to an embodiment. [Figure 6A] FIG. 6A is a perspective view of a dual-parallel arrangement of the screw conveyor reactor system of FIGS. 1-5, according to an embodiment. [Figure 6B] FIG. 6B is a side view of a dual parallel arrangement of the screw conveyor reactor system of FIGS. 1-5, according to an embodiment. [Figure 6C] FIG. 6C is a top view of a dual parallel arrangement of the screw conveyor reactor system of FIGS. 1-5, according to an embodiment. [Figure 6D] FIG. 6D is a perspective view of a dual-parallel arrangement of the screw conveyor reactor system of FIGS. 1-5, according to an embodiment. [Figure 6E] FIG. 6E is a front view of a dual-parallel arrangement of the screw conveyor reactor system of FIGS. 1-5, according to an embodiment. [Figure 6F] FIG. 6F is a perspective view of a dual-parallel arrangement of the screw conveyor reactor system of FIGS. 1-5, according to an embodiment. [Figure 7] FIG. 7 is a perspective view showing an Archimedes screw in isolation in a screw conveyor reactor system according to another embodiment. [Figure 8] FIG. 8 is a schematic block diagram of a conveyorized reactor system according to an embodiment. [Figure 9] FIG. 9 is a flowchart of a method of operating the screw conveyor reactor system of FIGS. 1 to 8 according to an embodiment. [Figure 10]FIG. 10 is a flow chart of a method of operating the screw conveyor reactor system of FIGS. 1 to 8 according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Various apparatus or processes are described below to provide examples of each claimed embodiment. The embodiments described below do not limit the claimed embodiments, which may be directed to processes or apparatuses different from those described below. The claimed embodiments are not limited to apparatus or processes having all the features of any one apparatus or process described below, or to features common to multiple or all of the apparatuses described below.

[0014] Furthermore, although process steps, method steps, algorithms, etc. may be described (in this disclosure and / or claims) in a sequential order, such processes, methods, and algorithms may be configured to operate in other orders. In other words, the order or sequence of steps described does not necessarily require that the steps be performed in that order. Steps of processes described herein may be performed in any order practical. Additionally, some steps may be performed simultaneously.

[0015] Where a single apparatus or article is described herein, it is clear that multiple apparatuses / articles (whether or not they work together) can be used in place of the single apparatus / article. Similarly, where multiple apparatuses or articles are described herein (whether or not they work together), it is clear that the single apparatus / article can be used in place of the multiple apparatuses or articles. Related to the screw conveyor reactor systems described herein are methods for breaking down plastic materials into terephthalic acid (TPA), ethylene glycol, and / or other monomers that form plastic materials.

[0016] The method includes contacting one or more plastic polymers with a metal oxide in solution in the presence of a base to provide a reaction mixture, stirring the reaction mixture under ultraviolet ("UV") light for a suitable period of time, and recovering terephthalic acid, ethylene glycol, and / or other monomers from the reaction mixture.

[0017] The process involves alkaline hydrolysis of a polymer, namely polyethylene terephthalate (PET), which can be carried out at room temperature with relatively high efficiency compared to other methods for breaking down polymers into their constituent monomers.

[0018] In some embodiments, the solvent is ethanol or a water-ethanol mixture. In some embodiments, the polymer is polyethylene terephthalate (PET). In some embodiments, the metal oxide is TiO. In some embodiments, the base is NaOH. In some embodiments, the initial pH of the reaction mixture is 14. In some embodiments, the reaction mixture is stirred at room temperature.

[0019] The recovered terephthalic acid may be of low purity, for example, it may be contaminated with various impurities and may require further processing to obtain commercially useful terephthalic acid, in which case it may be provided to a process configured to require virgin terephthalic acid.

[0020] In embodiments where the solvent is ethanol or a water-ethanol mixture, after the reaction mixture is stirred and the terephthalic acid is recovered, ethylene glycol may be present in the liquid mixture of water, ethanol, and ethylene glycol in various proportions, depending on the specific embodiment. Additional processing may be required to recover the ethylene glycol from the water-ethanol-ethylene glycol mixture. After separating the ethylene glycol from the water-ethanol-ethylene glycol mixture, the resulting water-ethanol-ethylene glycol mixture can be reused in additional operations or iterations of the processes described herein or in other processes.

[0021] Although the process described in more detail herein and in the specification of the '661 patent is described with respect to the degradation of polyethylene terephthalate into its constituent monomers, the process can also be applied to the degradation of other polymeric materials into their other constituent monomers.

[0022] Described herein are conveyorized reactor systems and related methods. While the systems and methods described herein may be particularly suitable for use in the room-temperature alkaline polymer hydrolysis processes described above and in U.S. Patent No. 5,949,999, in some embodiments, the conveyorized reactor systems described herein may be applicable to other processes as well.

[0023] 1 and 2, therein are depicted perspective views of a screw conveyor reactor system 100, according to an embodiment. The reactor system 100 includes a body 102, a hopper 104, a lid 108, a conveying system such as an Archimedes screw 112, a drive system 106, an outlet 140, and an ultraviolet (UV) assembly 110.

[0024] Body 102 includes a generally rectangular trough having a length extending along first axis 138. Body 102 is configured to be fluid-tight such that fluid introduced into body 102 does not leak from the body. Body 102 may be constructed from stainless steel or other materials that provide sufficient mechanical strength, fluid tightness, and chemical resistance to the contents present within body 102 during operation of system 100 (e.g., a highly basic substance with a pH of 14). While the embodiment shown herein comprises a generally rectangular shape, in other embodiments, body 102 may comprise other shapes.

[0025] The body 102 further includes a lid 108. The lid 108 is hinged to a sidewall of the body 102 such that the lid 108 can rotate between an open position 108a and a closed position 108b. When placed in the closed position 108b, the lid 108 seals the body 102 to prevent contents from spilling or volatile compounds from escaping from the body 102 during system operation, reducing the risk of exposure to volatile compounds to human operators near the system 100. In some examples, the interface between the body 102 and the lid 108 may include a gasket to provide a fluid-tight seal when in the closed position 108b. The gasket can provide a fluid-tight seal so that liquids and volatile compounds can be applied to the system 100.

[0026] In the embodiment of FIGS. 1 and 2, the lower portion of the body 102 has a rounded shape that mirrors the profile of the Archimedes screw 112.

[0027] The hopper 104 includes a container coupled to the body 102 at a first end 102a of the body. The hopper 104 is a generally square, funnel-shaped structure with an open top. In some embodiments, the hopper 104 can further include a removable lid to prevent materials or volatile substances from exiting the hopper 104 during operation of the system 100. The hopper 104 is coupled to the body 102 such that materials introduced into the hopper 104 exit the hopper 104 and pass through the body 102. The hopper 104 can be constructed of stainless steel or other materials that provide sufficient mechanical strength, fluid tightness, and chemical resistance to the contents present within the hopper 104 (e.g., a highly basic substance with a pH of 14) during operation of the system 100.

[0028] The hopper 104 is configured to receive input materials to the system 100, such as polymeric materials for degradation, solvents, pH-adjusting chemicals, catalysts, and / or other materials, and pass these materials through the main body 102. In some embodiments, the hopper 104 is not present in the system 100, and the system 100 can supply materials by alternative means. For example, another machine or component can directly input materials into the main body 102 through an opening in the main body 102. In some examples, the hopper 104 can be integrated into the main body 102 or another component of the system 100.

[0029] The drive system 106 comprises a device capable of imparting rotational motion to another object. The drive system 106 may comprise an electric motor, a gasoline engine, a diesel engine, the output shaft of another machine or system, or any other device that imparts rotational motion to another object. The drive system 106 may further include a gearbox for adjusting the output speed, control electronics, a rotational speed sensor, a torque sensor, an external control interface, or other auxiliary components.

[0030] The ultraviolet light assembly 110 includes components configured to emit light in the ultraviolet spectrum. The ultraviolet light assembly 110 can irradiate the contents of the body 102 with ultraviolet light. The ultraviolet light assembly 110 extends along the length of the body 102 so that contents at different locations within the body 102 are exposed to ultraviolet light during operation of the system 100. The outlet 140 comprises an opening coupled to the body 102 so that contents within the body 102 can be discharged from the system 100 through the outlet 140. In some examples, the size and shape of the outlet 140 can be specifically configured so that material discharged through the outlet 140 is extruded with a specific profile for further processing.

[0031] In some examples, system 100 may further include a cooling and / or heating system configured to maintain within a particular temperature range the components or environment of system 100. Such temperature control systems may be computer controlled and may be comprised of resistive heating elements, heat pumps, refrigeration systems, fuel-fired heating elements, or other suitable heating or cooling components.

[0032] 3, depicted therein is an isolated perspective view of a transport system, such as an Archimedes screw 112, of the reactor vessel system 100. The Archimedes screw 112 includes an elongated central shaft 116 extending along a central axis 114 and a continuous spiral blade 118 disposed substantially perpendicular to the central shaft 116 of the Archimedes screw 112. The spiral blade 118 has a dimension of pitch 124. The pitch 124 may vary depending on the particular application of the system 100.

[0033] The Archimedes screw 112 may be mounted to the body 102, the hopper 104, and / or other components of the system 100 in a manner that allows rotation of the Archimedes screw 112 about the central shaft 116. For example, the Archimedes screw 112 may be coupled to the body 102 via a rotary bearing. In some examples, such a rotary bearing is configured to be liquid-tight or chemically resistant.

[0034] As the Archimedes screw 112 rotates about the central shaft 116, the blades 118 force material along the length of the body 102 as the Archimedes screw 112 rotates, thereby conveying material from the hopper 104 into the body 102 and along the length of the body 102 from the first end 102a to the second end 102b. The Archimedes screw 112 may be constructed from stainless steel or another material that provides sufficient mechanical strength, fluid tightness, and chemical resistance to the contents (e.g., a highly basic substance with a pH of 14) present within the body 102 during operation of the system 100.

[0035] 1-3, the Archimedes screw 112 further includes three scoops 120 that extend parallel to or helically with the axis 114 along the length of the Archimedes screw 112 and periodically intersect with the spiral blades 118. In some embodiments, the scoops 120 do not extend all the way to the central shaft 116, such that there is a gap between each scoop 120 and the central shaft 116 along the length of the Archimedes screw 112 to allow for some liquid drainage through the Archimedes screw 112 during operation of the system 100. This liquid drainage provides more thorough mixing of the contents and may further reduce mechanical stress on the Archimedes screw 112, associated components (e.g., mounting hardware and bearings), and drive system 106, which in turn may reduce the torque requirements of the drive system 106.

[0036] Each scoop 120 has a concavely curved shape. This curved shape allows the Archimedes screw 112 to scoop up contents from the bottom of the body 102 and pull them to the top of the body 102 so that the contents are uniformly exposed to UV light during operation of the system 100. The exact size, number, and shape of the scoops 120 can be adjusted depending on the use case of the system 100. For example, if the use case of the system 100 involves conveying and mixing more viscous contents, the dimensions may be changed for more thorough mixing and reduced mechanical stress on the components. The curved shape of the scoops 120 in this embodiment reduces mechanical stress on the scoops 120 and the Archimedes screw 112, further reducing the torque requirements of the drive system 106.

[0037] The presence of the scoop 120 can facilitate mixing and agitation of the contents within the body 102 when the system 100 is operating and the Archimedes screw 112 is rotating. Additionally, the scoop 120 can mix and position the contents of the system 100 so that the contents are more uniformly exposed to the ultraviolet light emitted by the ultraviolet light assembly 110, thereby improving process efficiency.

[0038] Between each intersection of each scoop 120 and the spiral blade 118, there are two openings 122 present in the surface of each scoop 120. In this embodiment, each opening 122 is approximately elliptical in shape and has a large aspect ratio. According to some embodiments, the aspect ratio of each elliptical opening 122 is about 10. In other embodiments, a different number of openings 122 may be present on each scoop 120, and the openings 122 may include different sizes and shapes, including, but not limited to, circular, square, polygonal, or another shape.

[0039] The presence of openings 122 can promote mixing and agitation of the contents within body 102. According to some embodiments, this increased mixing and agitation can improve process efficiency. Additionally, openings 122 can mix and position the contents of system 100 to provide more uniform exposure to the ultraviolet radiation emitted by ultraviolet radiation assembly 110, thereby improving process efficiency.

[0040] Referring now to Figure 4, there is depicted a front cross-sectional view of the screw conveyor reactor system 100 taken along section AA of Figure 1. Figure 4 shows an Archimedes screw 112 disposed within the body 102. The body 102 has a bottom surface 128. The bottom surface 128 is comprised of a continuously curved section of material joining each vertical side of the body 102. The radius of curvature of the bottom surface 128 is configured to substantially match or correspond to the outer radius 126 of the Archimedes screw 112 such that there is little space between the outer contour of the Archimedes screw 112 and the bottom surface 128 when the Archimedes screw 112 is disposed in an operative position within the body 102. This configuration improves the ability of the Archimedes screw 112 to transport material along the body 102 from the first end 102a to the second end 102b, as there is little space between the outer radius 126 of the Archimedes screw 112 and the bottom surface 128 of the body 102 for material to settle and stagnate.

[0041] Also shown in FIG. 4 is a liquid level 134. The liquid level 134 is the level at which the mixture of fluids (e.g., solvents and other fluids) and input polymeric material rests when the system 100 is in an operating state. In some embodiments, it may be preferable for the liquid level 134 to rest above the outer diameter of the central shaft 116. This liquid level, according to some embodiments, can improve process efficiency over other liquid levels. According to some embodiments, this liquid level 134 provides an advantageous ratio of the volume of the reaction mixture to the surface area of ​​the reaction mixture in contact with the ultraviolet light. Increasing the liquid level above this height maintains the area of ​​the reaction mixture in contact with the ultraviolet light, but increases the volume of the reaction mixture. If the liquid level is lower than level 134, the area of ​​the reaction mixture in contact with the ultraviolet light may be reduced because the ultraviolet light may be blocked by the central shaft 116, scoop 120, and / or blades 118. This reduction in the ultraviolet light exposure area of ​​the reaction mixture may be greater than the reduction in volume, depending on the geometry of the system 100.

[0042] The body 102 further includes a vertical wall dimension 142, as seen in FIG. 4 . The vertical wall dimension 142 may be specifically configured to reduce the likelihood of contents within the body 102 being directed, lifted, or splashed above the top of the vertical wall dimension 142 when the system 100 is operating. This may reduce material splashing and residue buildup on components of the ultraviolet light assembly 110, which could reduce the intensity of the ultraviolet light output or damage the components of the ultraviolet light assembly 110. Similarly, as the distance between the ultraviolet light assembly 110 and the contents of the body 102 (e.g., liquid level 134) increases, the ultraviolet light intensity decreases according to an inverse square law. The vertical wall dimension 142 may be configured to optimize and balance splashing of contents and ultraviolet light intensity.

[0043] Referring now to FIG. 5, therein is depicted a detailed perspective view of the ultraviolet light assembly 110 of the reaction vessel system 100. The ultraviolet light assembly 110 further comprises a UV light source 130, a reflector 136, and UV screens 132a, 132b. The UV light source 130 comprises a light source that outputs electromagnetic radiation in the ultraviolet wavelength spectrum (wavelengths 10 nm to 400 nm). Preferably, the UV light source 130 outputs electromagnetic radiation in the UVA wavelength spectrum (wavelengths 315 nm to 400 nm) at a relatively high intensity. The UV light source 130 may be a fluorescent light source, a light-emitting diode light source, or other light source. In the embodiment of FIG. 5, the UV light source 130 is a fluorescent tube-type UV light source 130 comprising two parallel lengths of fluorescent tubes that emit ultraviolet light.

[0044] The reflector 136 is a component disposed between the UV light source 130 and the interior of the body 102. The reflector 136 reflects the UV light emitted by the UV light source 130 back into the interior of the body 102, improving the transmittance of UV light from the UV light source 130 to the contents of the body 102. Additionally, the reflector 136 prevents the UV light emitted by the UV light source 130 from escaping the interior of the body 102, reducing the risk of UV exposure to nearby personnel and operators of the reaction vessel system 100. The reflector 136 may be constructed of a polymer, metal, glass, or other suitable reflective material and may be coated with a thin layer of a UV-reflective coating. In other embodiments, the reflector 136 is configured to reflect the UV light it receives and block it from passing through the reflector 136.

[0045] The UV screen 132a is constructed from a solid component that is transparent to ultraviolet light. The UV screen 132a is positioned between the UV light source 130 and the interior of the body 102 to prevent contents within the body 102 from contacting the UV light source 130. In some applications of the system 100, the contents within the body 102 may be corrosive or otherwise damaging to sensitive electrical components, such as the UV light source 130 or associated components. The UV screen 132a advantageously protects the UV light source 130 from contact with the contents within the body 102, preventing damage to portions of the system 100. The UV screen 132a can be easily cleaned or maintained as needed.

[0046] The UV screen 132b is comprised of a solid component that is opaque to ultraviolet light but at least partially transparent to visible light. The UV screen 132b is positioned on the lid 108, covering the interior of the body 102, so that when the lid 108 is closed, visible light passes through the UV screen 132b of the lid 108, but ultraviolet light does not. The UV screen 132b has the advantage of allowing an operator to visually assess the contents and processes occurring in the body 102 when the lid 108 is closed and the system 100 is operating, while minimizing the risk of operator exposure to ultraviolet light that may be harmful to a human operator. The UV screen 132b can be easily cleaned or maintained as needed.

[0047] In some examples, the system 100 can alternatively include a flow of cooling or protective fluid in place of or in addition to the UV screen 132a. This fluid flow can prevent the contents of the body 102 or the system 100 from splashing onto the UV light source 130, preventing damage to the components of the system 100. Additionally, such a flow of cooling or protective fluid can remove heat from the UV light source 130, improving the performance or lifespan of the UV light source 130. Such a flow of cooling or protective fluid can be transparent to UV light and can include a flow of air, water, or other suitable fluid.

[0048] According to one embodiment, in operation of the screw conveyor reactor system 100, the polymeric material for decomposition is introduced into the hopper 104, and a solvent (e.g., ethanol or a water-ethanol mixture) is introduced into the body 102 either directly or through the hopper. Additionally, a metal oxide catalyst (e.g., TiO) and a base (e.g., NaOH) may be introduced into the body 102 either directly or through the hopper 104.

[0049] In some examples, the polymeric material introduced into the system 100 may be selected from a group including, but not limited to, polylactic acid (PLA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene isosorbide terephthalate (PEIT), polyethylene furanoate (PEF), polyvinyl chloride (PVC), and polyvinylidene chloride (PVDC), or combinations thereof.

[0050] In some examples, the solvent introduced into the system 100 may be selected from a group including, but not limited to, methanol, ethanol, propanol, butanol, pentanol, or combinations thereof.

[0051] In some examples, the catalyst introduced into the system 100 may be, but is not limited to, TiO2, V2O5, Cr2O3, CrO3, Mn2O3, FeO, Fe2O3, Fe3O4, Co2O3, NiO, CuO, Cu2O, ZnO, ZrO2, Nb2O5, Mo2O3, RuO, RuO2, RuO4, RhO2, Rh2O3, PdO, Ag2O, Ag 2O2, CdO, In2O3, Al2O3, La2O3, CeO2, Ce2O3, HfO2, Ta2O5, WO3, ReO2, ReO3, Re2O3, OsO2, OsO4, IrO2, PtO2, Au2O3, Li2O, Na2O, K2O, MgO, CaO, SrO, BaO, and P25, or a combination thereof.

[0052] In some examples, the base introduced into the system 100 may be, but is not limited to, NaOH, NaOMe, NaOEt, NaOPr, NaO t Bu, KOH, KOMe, KOEt, KO i Pr KO t Bu, LiOH, LiOMe, LiOEt, LiO i Pr, LiO t Bu, Rb(OH), RbOMe, RbOEt, RbO i Pr, RbO t BuCsOH, CeOMe, CsOEt, CsO i Pr, CsO t Bu, Fr(OH), FrOMe, FrOEt, FrO i Pr, FrO t Bu, Be(OH)2, Be(OMe)2, Be(OEt)2, Be(O i Pr)2, Be(O t Bu)2, Mg(OH)2, Mg(OMe)2, Mg(OEt)2, Mg(O i Pr)2, Mg( t OBu)2, Ca(OH)2, Ca(OMe)2, Ca(OEt)2, Ca(O i Pr)2, Ca( t OBu)2, Sr(OH)2, Sr(OMe)2, Sr(OEt)2, Sr(O i Pr)2, Sr( tOBu)2, Ba(OH)2, Ba(OMe)2, Ba(OEt)2, Ba(O i Pr)2, Ba( t OBu)2, Ra(OH)2, Ra(OMe)2, Ra(OEt)2, Ra(O i Pr), Ra(tOBu), and NH(OH), or a combination thereof.

[0053] Once these materials are introduced into the system 100, the drive system 106 and ultraviolet light assembly 110 are activated, imparting rotation to the Archimedes screw 112 and exposing the contents within the body 102 to ultraviolet light. As the Archimedes screw 112 rotates, the contents within the body 102 and hopper 104 are conveyed toward the second end 102b of the system 100. The contents of the system 100 are constantly mixed by the rotation of the Archimedes screw 112, which pulls the materials from the bottom of the body 102 to the top of the body 102 so that the contents can be exposed to ultraviolet light relatively uniformly.

[0054] The contents within the system 100 are conveyed from the hopper 104 and first end 102a toward the second end 102b and discharge outlet 140. As the contents move toward the second end 102b, the contents are continuously reacted until the contents reach the second end 102b and discharge outlet 140, at which point the contents have been fully treated according to the desired chemical treatment specifications applied by the system 100.

[0055] The components of the system 100 may be configured so that the desired chemical treatment is complete once the contents reach the second end 102b and the discharge port 140, or so that material exiting the discharge port 140 is completely treated. For example, the radius 126, pitch 124, and length of the Archimedes screw 124, the dimensions of the body 102 and hopper 104, the curvature, location, and number of the scoops 120, the number, shape, and size of the openings 122, the intensity of the ultraviolet light incident on the contents, the rotational speed of the Archimedes screw 112, and other parameters that may affect the treatment rate, may be configured depending on the desired chemical treatment applied by the system 100.

[0056] The mechanical design of system 100 is configured to improve chemical processing by applying a continuous process to avoid clogging of system 100 due to drying out of material or accumulation of material on UV light source 130, improving reaction mixing, ensuring that the reaction mixture is homogeneous and in regular contact with UV light through blade action, maintaining the homogeneity of the reaction mixture, ensuring that input reactants do not settle or stagnate within system 100, and ensuring that the reaction mixture is constantly moving and in constant contact with UV light.

[0057] The modular mechanical design of system 100 also allows the process performed by system 100 to be scaled and optimized as needed. For example, multiple systems 100 can be linked together to increase the scale of the underlying process. The overall structure and design of system 100 allows for easy access to the internal services of body 102, facilitating cleaning and maintenance. Furthermore, because system 100 is easily accessible through lid 108, system 100 can be maintained, modified, or serviced while in operation.

[0058] 6A-6F, depicted therein are various combinations of screw conveyor reactor system 100, depicted with and without various components arranged in a parallel configuration. The screw conveyor reactors do not include hoppers; instead, the outlet of a first screw conveyor reactor feeds the inlet of a second screw conveyor reactor, while the outlet of the second screw conveyor reactor feeds the inlet of the first screw conveyor reactor. This dual parallel arrangement, in contrast to the configuration of the embodiment of FIGS. 1-5, allows for continuous operation in which material within the body of screw conveyor reactor system 100 is continuously circulated between the screw conveyor devices, input material is fed to hopper 104 and conveyed along body 102, the input materials are mixed, and the mixture is exposed to UV light to complete a desired chemical process (e.g., room-temperature degradation of PET). In the embodiment of Figures 6A-6F, the pair of screw conveyor reactor systems 600 can accommodate a total of 150 L of fluid within the bodies of both reactors (i.e., each reactor can contain 75 L of fluid). Screw conveyor reactor system 600 can be screw conveyor reactor system 100 described with reference to Figures 1-5.

[0059] In the embodiment of Figures 6A-6F, screw conveyor reactor system 600 can be connected in a series or loop configuration. In a series configuration, reactors can be connected in a planar or vertical mode. In a vertical mode, the system may be configured to operate in an ascending or descending configuration. In a descending configuration, the contents of a reactor may be forced by gravity toward the outlet or the next reactor in the series. In an ascending configuration, a reactor can be positioned so that its outlet is at the same vertical level as the inlet of the next reactor. System 600 is configured with similar components to systems 100 and 400, with reference letters incremented by 500 and 200, respectively. The discussion herein regarding systems 100 and 400 equally applies to system 600.

[0060] For example, Figures 6A-6F show a main body 602, a drive system 606, a UV light 610, and a transport subsystem 612. Also shown in Figures 6C and 6E is a system coupling 644. The system coupling 644 couples the individual reaction vessel systems 600 together to form a loop or series configuration, allowing material from one reaction vessel system to be transferred to another reaction vessel system via the system coupling 644. While the system coupling 644 is shown in a particular configuration and location, in other embodiments, the configuration, number, and location of the system coupling 644 may differ.

[0061] Referring now to FIG. 7 , depicted therein is an alternative embodiment of an Archimedes screw 312 for use in a screw conveyor reactor system such as system 100 described herein. Screw 312 differs from screw 112 in that screw 312 includes two scoops 320, as opposed to the three scoops 120 of screw 112. Furthermore, the scoops 320 of screw 312 are configured in a helical arrangement, as opposed to the linear arrangement of scoops 120. Each scoop 320 rotates 180° radially along the length of screw 312, such that scoop 320 begins at a first position at one end of screw 312 and is positioned 180° away from the first position at the opposite end of screw 312, opposite the central axis of screw 312. This radial rotation of scoops 320 can increase process efficiency by more uniformly exposing the contents of system 100 to UV light during operation.

[0062] Referring now to Figure 8, there is depicted a schematic block diagram of a conveyorized reactor system 400, according to an embodiment. System 400 includes a body 402, a drive system 406, a transport system 412, a UV light 410, an optional discharge port 440, and a hopper 404. The components of system 400 may have the attributes of system 100, with the reference letters of each component incremented by 300. Details of the components of system 100 may also apply to system 400.

[0063] Body 402 comprises a structure that holds and contains process inputs such as polymers, solvents, bases, metal oxides, other fluids, solids, or mixtures. Body 402 is the main vessel or container in which chemical reactions take place.

[0064] Conveying system 412 is disposed within body 402 and is configured to transport material from one location within body 402 to another location within body 402. Conveying system 412 also mixes the contents within body 402 to ensure uniformity of the contents within body 402 and to uniformly expose the contents of body 402 to UV light. Conveying system 412 includes a structure or device that transports the contents from one location within body 402 to another location.

[0065] Drive system 406 comprises a device coupled to transport system 412 to impart motion to transport system 412. Drive system 406 can be comprised of a motor, an engine, an actuator, an external force input (e.g., an input shaft), or other device for imparting motion to other devices.

[0066] The UV light 410 comprises a device that outputs electromagnetic radiation in the wavelength range of 10 nm to 400 nm. The UV light 410 is positioned above the body 402 so that the contents of the body 402 are exposed to UV wavelength light during operation of the system 400. In some examples, the UV light 410 may be integrated into the body 402.

[0067] System 400 may optionally further include a hopper 404 and a discharge outlet 440. Hopper 404 is coupled to body 402 such that material is introduced into hopper 404 and passed through body 402. In some examples, hopper 402 is integral with body 402 such that body 402 and hopper 404 are comprised of a single component.

[0068] The outlet 440 comprises a structure coupled to the body 402 such that contents within the body 402 may be vented from the system 400 through the outlet 440. In some examples, the outlet 440 may be integrated into the body 402 such that the outlet 440 and the body 402 form a single component.

[0069] In some examples, outlet 440 may be configured with different shapes and locations. Outlet 440 may be located at the bottom of body 402, laterally disposed about body 402, or aligned with the axis of transport system 412. Outlet 440 may further include a strainer or other component configured to collect, separate, or filter materials being discharged from system 400, such as unreacted solution, impurities, or other materials of interest.

[0070] Referring now to Figure 9, depicted therein is a flow chart outlining a method 200 of operating the screw conveyor reactor system of Figures 1-8. Method 200 includes steps 202, 204, 206, 208, and 210. Although the flow chart of Figure 9 depicts an ordered, linear method, method steps 202, 204, 206, 208, and 210 may be performed in any order. In step 202, a screw conveyor reactor system is provided. The screw conveyor reactor system may be the screw conveyor reactor system 100 described with reference to Figures 1-8, or a variation thereof. In step 204, the polymeric material is introduced into a hopper of the reactor vessel system. In step 206, a solvent is introduced into the hopper of the reactor vessel system. In step 208, the drive system of the reaction vessel system is activated. In step 210, the UV light in the reaction vessel system is activated. In some examples of method 300, step 206 may be performed first, followed by step 208, and then step 204.

[0071] Referring now to Figure 10, depicted therein is a flow chart outlining an alternative method 300 of operating the reaction vessel system of Figures 1-8. Method 300 may include any or all of the steps of method 200, in any order, and further includes steps 302 and / or 304. In step 302, the base is fed into a hopper. In step 304, metal oxide is fed into a hopper.

[0072] While the above description illustrates one or more example devices, methods, or systems, it will be understood that other devices, methods, or systems may be included within the scope of the claims as interpreted by one of ordinary skill in the art.

Claims

1. 1. A reactor vessel system for decomposing polymeric materials, comprising: a hopper for receiving input materials including a polymer, a solvent, a metal oxide, and a base; a body extending along a first axis and having a first end and a second end, the first end being coupled to the hopper and capable of receiving input material introduced into the hopper; a conveying system for conveying the input material along the body; a drive system for imparting motion to the transport system; and an ultraviolet ("UV") light for exposing the input material within the body to ultraviolet light to decompose the input material.

2. The system of claim 1 , wherein the body is liquid-tight and the liquid is contained by the body.

3. 3. The system of claim 1, wherein the polymer comprises any one of polylactic acid, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene isosorbide terephthalate, polyethylene furanoate, polyvinyl chloride, and polyvinylidene chloride, or a combination thereof.

4. The system according to any one of claims 1 to 3, wherein the conveying system is disposed within the reaction vessel system so that the conveying system can convey material introduced into the hopper from the hopper into the body.

5. 5. The system of claim 1, wherein the transport system is disposed within the reactor vessel system such that the transport system can transport material from the first end of the body to the second end of the body.

6. 6. The system of any one of claims 1 to 5, wherein the conveying system comprises an Archimedes screw, the Archimedes screw having a central shaft, the Archimedes screw configured to convey input material along the body.

7. 7. The system of claim 6, wherein the drive system is coupled to the Archimedes screw, and the drive system is configured to rotate the Archimedes screw about a central shaft of the Archimedes screw.

8. 8. The system according to any one of claims 6 to 7, wherein the Archimedes screw has a length of 1 meter to 10 meters.

9. A method of operating the system of any one of claims 1 to 8, comprising: feeding a polymeric material into said hopper; supplying a solvent to the hopper; operating the drive system; and activating the UV light.

10. The method of claim 9 , wherein the solvent comprises ethanol.

11. The method of any one of claims 9 to 10, further comprising the step of feeding metal oxide to the hopper.

12. The method of any one of claims 9 to 11, further comprising the step of feeding a base to the hopper.

13. 13. The method of claim 12, wherein the material fed to the reaction vessel has a pH greater than 7.

14. A method according to any one of claims 9 to 13, wherein the drive system is configured to rotate the transport system at a speed in excess of 30 revolutions per minute.

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