Depolymerization catalyst systems and processes

Abstract

Catalyst compositions and processes for the depolymerization of polyolefinic feeds into useful petrochemical products are described. The compositions are composites of a zeolite catalyst component and a cocatalyst comprising an activated clay component and / or a solid base component. These catalyst systems are used in conjunction with heat to enhance the depolymerization reaction rate of the feedstream while simultaneously suppressing the poisoning effects of impurities that may be present in the polyolefinic feed. This reduces residence time in the depolymerization unit, allowing for a more efficient process.

Description

[Technical Field]

[0001] The present disclosure relates to a method for depolymerizing polyolefin-based materials using a catalyst system comprising a combination of a zeolite catalyst and a co-catalyst comprising an activating clay component and / or a solid base component to form useful petrochemical products such as olefin monomers. [Background technology]

[0002] Rising living standards and urbanization are driving demand for polymer products, especially polyolefin plastics. Polyolefins are commonly used in commercial plastic applications due to their outstanding performance and cost characteristics. For example, polyethylene (PE) is one of the most widely used and recognized polyolefins due to its high strength, exceptional toughness, and durability, which allows it to be highly engineered for a variety of applications. Similarly, polypropylene (PP) is mechanically strong yet flexible, heat-resistant, and resistant to many chemical solvents, including bases and acids. This makes it suitable for a variety of end-use industries, primarily packaging and labeling, textiles, plastic components, and various reusable containers.

[0003] The downside to the demand for polyolefin plastics is the increase in waste. Post-consumer plastic waste is typically disposed of in landfills, with approximately 12% being incinerated and approximately 9% being recycled. Most plastics do not decompose rapidly in landfills, making them a major source of waste, contributing to overburdened landfills. Incineration is also not an ideal solution for treating plastic waste because it results in the formation of carbon dioxide and the emission of other greenhouse gases. Therefore, there is growing interest in developing methods for recycling plastic waste to reduce the burden on landfills while still being environmentally friendly.

[0004] A drawback of recycling plastic waste is the difficulty of successfully producing commercially usable or desired products. Currently, recycling plastic waste involves cleaning the material and mechanically reprocessing it, but the resulting pellets are still contaminated with impurities such as food residues, dyes, and flavorings. These impurities make the pellets unsuitable for many applications in terms of both performance and appearance. Furthermore, because it is difficult to obtain a pure stream of a particular polymer, mixed plastic waste streams may not have the desired properties after recycling.

[0005] Recent advances have focused on converting plastic waste into useful products, such as fuel sources and commercially important raw materials. Methods have been developed to pyrolyze plastic waste streams, followed by catalytic depolymerization, to produce a variety of products, including gas, gasoline fractions, kerosene fractions, diesel fractions, and waxes. Unfortunately, the catalysts themselves are prone to contamination by other chemicals contained in the polyolefin waste feedstock, making the process expensive and time-consuming, as significant energy is required to completely decompose the polyolefin waste into useful product classes.

[0006] Despite advances in polyolefin recycling, there is a continuing need to develop robust processes for converting polyolefin-rich waste feedstocks into useful petrochemical products. Ideally, these processes would overcome the "poisoning" caused by other polymers and contaminants that may be present in the waste feedstock. Summary of the Invention

[0007] The present disclosure provides novel compositions and methods for thermally depolymerizing polyolefin-based materials in the absence of oxygen. The presently disclosed compositions are combinations of a zeolite catalyst component and a co-catalyst comprising an activated clay component and / or a solid base component to form useful petrochemical products, such as olefin monomers. The combination of the zeolite catalyst component and the co-catalyst has a synergistic effect of increasing the rate of the depolymerization reaction while also suppressing any poisoning effects resulting from impurities or decomposition products of impurities that may be present in the feed stream. Specifically, the zeolite catalyst component and the co-catalyst comprising an activated clay component and / or a solid base component form a robust depolymerization catalyst system. The components of the depolymerization catalyst system are added to separate depolymerization reaction zones in a depolymerization process comprising at least two depolymerization reaction zones. The reaction mixture in each pyrolysis reaction zone is heated in the absence of oxygen in a process called pyrolysis to rapidly produce useful petrochemical products.

[0008] In some embodiments, a catalyst system for depolymerizing polymers includes a zeolite catalyst component and a co-catalyst including an activated clay component, a solid-based component, or a combination thereof.

[0009] In some embodiments, a process for depolymerizing a polymer includes: a) adding a polyolefin feed stream and a first cocatalyst to a first pyrolysis reaction zone to form a first reaction mixture, wherein the first cocatalyst comprises an activated clay component, a solids-based component, or a combination thereof; b) reacting the first reaction mixture under first depolymerization conditions in the absence of oxygen to form a first vapor product and a char; c) adding the vapor product to a first condensation zone, wherein the first vapor product is subjected to condensation conditions to form a second vapor product and a first liquid product; d) adding the first liquid product and a zeolite catalyst component to a second pyrolysis reaction zone to form a second reaction mixture; and e) reacting the second reaction mixture under second depolymerization conditions in the absence of oxygen to form a third vapor product, a second liquid product, and a char, wherein the second liquid product comprises one or more olefin monomers.

[0010] In some embodiments, a depolymerization system comprises: a) a pyrolysis reaction zone for heating a mixture of a polyolefin-based feed stream, a zeolite catalyst, and a co-catalyst comprising an activated clay component, a solid-based component, or a combination thereof to produce a vapor product and a char; and b) a condensation unit for condensing the vapor product to produce a second vapor product and a liquid product comprising one or more olefin monomers.

[0011] In some embodiments, a depolymerization system comprises: a) a first pyrolysis reactor for heating a mixture of a polyolefin-based feed stream and a first cocatalyst to produce a first vapor product and a char; b) a first condensing unit for condensing the first vapor product to produce a second vapor product and a first liquid product; c) a second pyrolysis reactor for heating a mixture of the first liquid product and, optionally, a second cocatalyst to produce a second liquid product and a char; and d) a second condensing unit for condensing the second liquid product and, optionally, the second vapor product to produce a third vapor product and a third liquid product comprising one or more olefin monomers.

[0012] The foregoing has outlined, rather broadly, the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter, and these form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other catalyst compositions and / or processes for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features of the present invention, including compositions and methods thereof, as well as other objects and advantages, will be better understood from the following description. [Brief explanation of the drawings]

[0013] The claimed subject matter can be understood by reference to the following description in conjunction with the accompanying drawings, in which like reference numerals indicate like elements and in which:

[0014] [Figure 1] FIG. 1 is a simplified flow chart of the disclosed process having two depolymerization reaction zones and two condensation zones, in accordance with an embodiment of the present invention. [Figure 2]FIG. 2 is a flow chart of a particular embodiment of the disclosed process having two depolymerization reaction zones and two condensation zones. [Figure 3] Figure 3 shows an overlaid graph of the zeolite catalyst performance alone and with the addition of a co-catalyst in a waste plastic depolymerization sample.

[0015] While the disclosed processes and structures are susceptible to various modifications and alternative forms, the drawings show by way of example specific embodiments which have been described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but rather the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. DETAILED DESCRIPTION OF THE INVENTION

[0016]

[0013] Exemplary embodiments of the claimed subject matter are disclosed below. For clarity, some features of some actual implementations may not be described herein. It will be understood that in the development of any such actual implementation, various implementation-specific decisions will be made to achieve the specific goals of the developer, such as extensibility related to system-related and business-related constraints, which will vary from implementation to implementation. It will further be understood that such a development effort, while complex and time-consuming, would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

[0017] The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning understood by those skilled in the art, is intended to be implied by the consistent use of a term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than the broadest meaning understood by those skilled in the art, such special or specific definition will be expressly set forth in the definitions section of the specification to provide a special or specific definition of the term or phrase. It should also be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include the plural unless otherwise specified.

[0018] For example, the following description includes a non-exhaustive list of definitions of some specific terms used in this disclosure (other terms may be definitionally defined or clarified elsewhere in this document). These definitions are intended to clarify the meaning of the terms as used herein. While it is believed that these terms are used in a manner consistent with their common meaning, the definitions are still specified here for clarity. definition

[0019] As used herein, "activated clay" describes clays or clay minerals, including but not limited to smectites or bentonites (including montmorillonite, nontronite, beidellite, and saponite); aluminosilicates, sepiolite, attapulgite (palygorskite); kaolin; and other fuller's earths that have been chemically treated with dilute acid (e.g., sulfuric acid) and heat-treated at 100°C to 200°C.

[0020] As used herein, "char" means coke, a carbon-containing solid that accumulates on catalyst particles during pyrolysis.

[0021] As used herein, "feedstream" refers to a supply of polyolefin-based material for depolymerization. Depending on the depolymerization unit, the feedstream may be a continuous supply of material or a batch of material. The feedstream may be pure polyolefin or a mixture of polyolefin and non-polyolefin components.

[0022] As used herein, "non-polyolefin components" refers to materials present in a polyolefin feedstock or waste stream that may reduce the ability of a zeolite to catalyze the depolymerization of polyolefins present in the stream. Examples of non-polyolefin components include non-polyolefin polymers that have high oxygen and / or nitrogen content.

[0023] As used herein, "post-consumer waste" refers to waste generated by the ultimate consumer of a material stream.

[0024] As used herein, "post-industrial waste" refers to waste generated during the manufacturing process of a product.

[0025] As used herein, "reaction zone" refers to a chamber sufficiently enclosed to maintain selected operating conditions within the chamber to produce desired reactants, such as a pyrolysis reaction zone or a condensation reaction zone. In some embodiments, each reaction zone can be a separate reactor. In some embodiments, a single vessel can contain multiple reaction zones.

[0026] As used herein, "residence time" refers to the time required to depolymerize one batch of polymer waste in a depolymerization unit.

[0027] As used herein, "pyrolysis" refers to a thermal depolymerization reaction that occurs in the absence of oxygen.

[0028] As used herein, a "waste stream" is a type of feed stream that contains materials that are discarded as unwanted, including but not limited to post-consumer and post-industrial waste.

[0029] As used herein, "zeolite" refers to an aluminosilicate mineral having a microporous structure. Zeolites, in one aspect, are useful as catalysts for the processes disclosed herein. Zeolites can be naturally occurring or industrially produced.

[0030] As used herein, the term "depolymerization half time" or "half time of depolymerization" refers to the time required to achieve 50% mass loss of a sample at a particular temperature during a TGA pyrolysis reaction. The depolymerization half life is related to the residence time required for large-scale industrial depolymerization reactors.

[0031] It is noted that in this disclosure, and particularly in the claims and / or paragraphs, terms such as "comprises," "comprised," "comprising," and the like can have the meaning ascribed to them in U.S. patent law, e.g., they can mean "includes," "included," "including," and the like, and "consisting essentially of" and "consists essentially of" have the meaning ascribed to them in U.S. patent law, e.g., they permit elements not expressly recited, but exclude elements discovered in the prior art or which do not affect the basic or novel characteristics of the present disclosure.

[0032] The term "pure" as used with respect to a feedstream refers to a material that is 100% polyolefin, but does not mean that the feed contains only one type of polyolefin. Conversely, a "pure" feedstream can have a mixture of polyolefins, such as low density polyethylene, high density polyethylene, polypropylene, and combinations thereof.

[0033] The terms "polyolefin-based" and "polyolefin-rich" when used with respect to a material, feed, or waste stream are used interchangeably to mean a mixture that is at least 80% polyolefin.

[0034] All concentrations herein are in weight percent ("wt %") unless otherwise specified.

[0035] In the claims or specification, when used in conjunction with the word "comprising," the use of the words "a" or "an" means one or more of the words, unless the context dictates otherwise.

[0036] The term "about" refers to the stated value plus or minus the error of measurement, or plus or minus 10% if no measurement method is given.

[0037] Use of the term "or" in the claims means "and / or" unless expressly stated to refer to alternatives only or where the alternatives are mutually exclusive.

[0038] The terms "comprise," "have," "include," and "contain" (and variations thereof) are open-ended linking verbs that, when used in the claims, allow for the addition of other elements.

[0039] The phrase "consisting of" is closed and excludes all additional elements.

[0040] The phrase "consisting essentially of" excludes additional significant elements, but allows for the inclusion of minor elements that do not materially alter the essence of the invention.

[0041] The phrase "substantially all" means 95% by weight or more, 99% by weight or more, 99.5% by weight or more, or 99.9% by weight or more.

[0042] The following abbreviations are used herein: [Table 1] catalyst composition

[0043] The present disclosure provides a catalyst composition for recycling polyolefin-based materials into commercially important feedstocks. In some embodiments, the catalyst composition for depolymerizing a polyolefin-based feed stream in a depolymerization unit comprises, or consists essentially of, a zeolite catalyst component and a cocatalyst comprising an activating clay component and / or a solid-based component. The components of the composite catalyst system act synergistically to increase the depolymerization rate and reduce the time the polyolefin-based feed stream spends in the depolymerization unit. The improved depolymerization rate occurs even when impurities, such as non-polyolefin components, are present in the feed stream that can reduce the catalytic activity of the zeolite in the absence of the cocatalyst comprising an activating clay component and / or a solid-based component. -Zeolite catalyst component

[0044] Zeolites are solid acid catalysts with an open three-dimensional crystalline structure containing numerous pores and acidic active sites that can initiate chemical reactions, such as the pyrolytic polymerization of polyolefins. Depolymerization occurs through hydrogen transfer reactions at the acidic sites of the zeolite to generate intermediate carbenium ions, which then decompose. Zeolites essentially rely on their strong acidic sites to decompose polyolefins. This decomposition process begins on the surface of the zeolite, because the polymer must be broken down into smaller molecules due to the small openings before entering the interior voids of these solids. This increases contact between the polyolefin and the catalyst, resulting in faster depolymerization rates and shorter residence times in the depolymerization unit.

[0045] Zeolites have many advantages for depolymerizing polyolefins, including the ability to tailor acidity and pore size to address the characteristics of a particular feed stream. In addition, zeolites are heterogeneous catalysts, allowing for easy separation and recycling from the depolymerization products or by-products.

[0046] However, zeolite catalysts are susceptible to poisoning in the presence of non-polyolefin components, such as polymers with nitrogen-containing groups and / or high oxygen content, and / or their depolymerization products, such as furfural, reducing catalytic activity. Additionally, many substrates with high oxygen and nitrogen content can form coke deposits on the zeolite, further reducing its activity. Polyolefin waste feedstreams are rarely pure, even after multiple separation steps at recycling facilities, and even small amounts of non-polyolefin components can suppress the catalytic capacity of zeolites, reducing depolymerization rates by as much as 85%.

[0047] The composite catalyst can be a zeolite catalyst capable of catalyzing the depolymerization reaction of polyolefins. In some embodiments, the composite catalyst can be a zeolite beta (β), zeolite Socony Mobil-5 (ZSM-5), zeolite Y (Y), ultrastable zeolite Y (USY), amorphous acidic AlSiO x, Siral® 40, or combinations thereof. Combinations of zeolites can be used to address specific polyolefin-based feed content or to offset the costs associated with using only an expensive zeolite in the composite.

[0048] In some embodiments, the zeolite catalyst component has a SiO2 / Al2O3 ratio of 200 or less, 100 or less, 50 or less, 25 or less, or 15 or less. In some embodiments, the zeolite catalyst component has a SiO2 / Al2O3 molar ratio in the range of 200:1-3:1, 150:1-3:1, 100:1-3:1, 50:1-3:1, 25:1-3:1, or 15:1-3:1. In some embodiments, the zeolite catalyst component has a SiO2 / Al2O3 molar ratio in the range of 200:1-5:1, 150:1-5:1, 100:1-5:1, 50:1-5:1, 25:1-5:1, or 15:1-5:1. In some embodiments, the zeolite catalyst has a SiO2 / Al2O3 molar ratio in the range of 200:1 to 10:1, 150:1 to 10:1, 100:1 to 10:1, 50:1 to 10:1, 25:1 to 10:1, or 15:1 to 10:1. In some embodiments, the zeolite catalyst has a SiO2 / Al2O3 molar ratio in the range of 200:1 to 1:1, 150:1 to 1:1, 100:1 to 1:1, 50:1 to 1:1, 25:1 to 1:1, or 15:1 to 1:1. - Cocatalyst

[0049] The present compositions and methods overcome these challenges by combining at least one zeolite with a co-catalyst comprising an activating clay component and / or a solids base component capable of suppressing the poisoning effects of impurities, such as non-polyolefin components, in a polyolefin-based feed stream. The co-catalyst maintains and / or restores the ability of the zeolite catalyst component to destroy polyolefins. In addition to reducing and / or preventing zeolite inhibition by impurities in polyolefin-rich feeds, the co-catalyst comprising an activating clay component and / or a solids base component unexpectedly synergizes with one or more zeolites to improve the depolymerization rate of the polyolefin-based feed stream beyond that of the zeolite alone, particularly when the polyolefin-based feed contains impurities. Activated Clay

[0050] For purposes of the present invention, activated clay is understood to mean clay that has been subjected to a thermal or chemical activation process. In some embodiments, the clay is activated by treatment with dilute sulfuric acid and drying at a temperature ranging from 100°C to 200°C. Activated clay can also be understood as "acid-washed clay." Clays (not subjected to an activation process) include one or more of the following non-limiting examples of clay minerals (phyllosilicates): attapulgite (palygorskite), albite, aluminosilicates, beidellite, bentonite, chlorite, fuller's earth, gibbsite, goethite, halloysite, hectorite, hematite, alpha hematite, illite, kaolinite, kaolin, metahalloysite, mica (including muscovite 2-M1 and / or illite-1M), montmorillonite, nontronite, pyrite, quartz, talc, saponite, sauconite, sepiolite, smectite, vermiculite, and other similar compositions. In some embodiments, the activated clay is a mixture of several activated clays with different properties, or a mixture of a single activated clay with one or more unactivated clays.

[0051] In some embodiments, the chemical composition of the activated clay has an Al2O3 content greater than 10 wt%, ranging from 10 wt% to 50 wt%, or 15 wt% to 30 wt%. In some embodiments, the activated clay has an Fe2O3 content greater than 5 wt%, ranging from 1 wt% to 60 wt%, 3 wt% to 20 wt%, or 5 wt% to 20 wt%. In some embodiments, the activated clay contains other components such as SiO2, Na2O to KO.

[0052] The activated clay cocatalyst in this composite catalyst is an inorganic material with acidic characteristics. Zeolites rely on strong acidic sites to initiate the depolymerization of polyolefins. Therefore, acidic cocatalyst compounds can be used as cocatalysts without affecting the initiation method of the zeolite.

[0053] The amount of activated clay cocatalyst(s) in the composite catalyst depends on the content of the polyolefin feedstock and the type (if any) of non-polyolefin components and their amounts in the feedstream. In some embodiments, the total amount of activated clay cocatalysts is in the range of 10% to 90% by weight, or 20% to 60% by weight of the composite catalyst, with the remainder, if any, being the total amount of zeolite and solids. Alternatively, the total amount of activated clay cocatalysts is in the range of 40% to about 75% by weight of the composite catalyst. Alternatively, the total amount of activated clay cocatalysts is in the range of 70% to 90% by weight of the composite catalyst. Alternatively, the total amount of activated clay cocatalysts is in the range of 50% to 75% by weight of the composite catalyst. Solid Base

[0054] In some embodiments, the solid base component is a layered double hydroxide composition; an activated carbon composition; or a combination thereof.

[0055] In some embodiments, the solid base component is a layered double hydroxide composition; an MR composition (wherein M is an alkali metal, alkaline earth metal, transition metal, post-transition metal, metalloid, or combination thereof, and R is an oxide, hydroxide, carbonate, sulfate, sulfide, nitrate, nitride, phosphate, phosphite, halide, or combination thereof); an activated carbon composition; or a combination thereof.

[0056] In some embodiments, the layered double hydroxide is hydrotalcite, quintinite, vogelite, woodwardite, quarstivite, glaucoserinite, wormlandite, hydrocalumite, or a combination thereof, hi some embodiments, the layered double hydroxide is hydrotalcite.

[0057] In some embodiments, the MR composition is Ca(OH), Mg(OH), Ba(OH), Sr(OH), CaO, AlO, or a combination thereof. In some embodiments, the MR composition is Ca(OH), or a combination thereof. In some embodiments, the solid base is a metal oxide or metal hydroxide. Any known metal oxide or metal hydroxide can be used, including metal oxides or hydroxides containing metals from groups 2 to 8 and 11 to 16, lanthanides, and actinides. Examples of solid inorganic promoters include Ca(OH), Mg(OH), Ba(OH), Sr(OH), NaOH, KOH, CaO, and AlO. Any combination of solid base promoters can be used. In some embodiments, the composite catalyst has both AlO and Ca(OH).

[0058] The solid base component can be a silicate, aluminosilicate, carbonate, phosphate, oxide, or hydroxide. Zeolites rely on strong acid sites to initiate the depolymerization of polyolefins. However, it has been surprisingly found that basic cocatalyst compounds can also be used without neutralizing the acid sites of the zeolite or affecting its ability to decompose polyolefins.

[0059] The amount of solids-based cocatalyst(s) in the composite catalyst depends on the content of the polyolefin feedstock and the type (if any) of non-polyolefin components and their amounts in the feedstream. In some embodiments, the total solids-based cocatalyst amount is in the range of 10% to 90% by weight, or 20% to 60% by weight of the composite catalyst, with the remainder, if any, being the total amount of zeolite and activated clay. Alternatively, the total solids-based cocatalyst amount is in the range of 40% to about 75% by weight of the composite catalyst. Alternatively, the total solids-based cocatalyst amount is in the range of 70% to about 90% by weight of the composite catalyst. Alternatively, the total solids-based cocatalyst amount is in the range of 50% to 75% by weight of the composite catalyst. Depolymerization Process

[0060] In some embodiments of the present disclosure, the composite catalyst is a combination of a zeolite catalyst with an activated clay cocatalyst, a solid-based cocatalyst, or a combination thereof, where the zeolite catalyst is present in the range of 25% to 50% by weight of the composite catalyst. The zeolite catalyst can be one or more ZSM-5 zeolites, one or more beta zeolites, one or more Y zeolites, one or more ultrastable Y zeolites, or a combination thereof. In some embodiments, the zeolite catalyst is one or more ultrastable Y zeolites.

[0061] The composite catalysts described thus far can be used to pyrolyze or depolymerize feedstreams containing materials containing a single polyolefin component or a mixture of polyolefin components in any amount. Any polyolefin can be present in the feedstream, including, but not limited to, polyethylene (both high and low density), polypropylene, ethylene-propylene copolymers, polybutene-1, polyisobutene, and copolymers thereof. Furthermore, the feedstream is not limited to a particular form, so that films, foams, textiles, or other forms of materials can be processed using the present method. Polyolefins can be obtained from wastestreams, including post-consumer wastestreams, post-industrial wastestreams, or combinations thereof.

[0062] In some embodiments, the feed stream further contains one or more non-polyolefin components that reduce the catalytic activity of the zeolite. Alternatively, the feed stream may further contain one or more non-polyolefin components that produce decomposition products that reduce the catalytic activity of the zeolite. While many chemicals fall into this category, non-polyolefin polymers are most likely to be present in polyolefin feed streams, especially when the feed stream is a waste stream. In particular, non-polyolefin polymers with high nitrogen or oxygen content, such as polyaramids, acrylates, nylons, polyurethanes, cellulose, and polyvinyl polymers, may be present in the feed stream. These polymers are typically found at waste sites and are difficult to completely separate from polyolefins. Many of these polymers decompose into problematic products, such as furfural, caprolactam, various amines, phenols, and esters, that reduce the catalytic performance of the zeolite. Alternatively, non-polyolefin components, such as nitrogen-containing pigments, may be present in polyolefin waste streams and reduce the catalytic activity of the zeolite.

[0063] In some embodiments, a process for depolymerizing a polymer includes: a) adding a polyolefin-based feed stream and a first co-catalyst to a first pyrolysis reaction zone to form a first reaction mixture, the first co-catalyst comprising an activated clay component, a solid-based component, or a combination thereof; b) reacting the first reaction mixture under first depolymerization conditions in the absence of oxygen to form a first vapor product and a first liquid product comprising char; and c) adding the first vapor product to a first condensation zone. wherein the first vapor product is passed through condensing conditions to form a second vapor product and a second liquid product; d) adding the second liquid product and a zeolite catalyst component to a second pyrolysis reaction zone to form a second reaction mixture; and e) reacting the second reaction mixture under second depolymerization conditions in the absence of oxygen to form a third vapor product and a third liquid product comprising char, wherein the third liquid product comprises one or more olefin monomers.

[0064] In further embodiments of the process for depolymerizing a polymer, the polyolefin feed stream comprises polyethylene, polypropylene, or a combination thereof. In some embodiments, the polyolefin feed stream comprises 0 wt.% to up to 20 wt.%, 0 wt.% to up to 15 wt.%, 0 wt.% to up to 10 wt.%, or 0 wt.% to up to 5 wt.% impurities, where the weight percentages are based on the total weight of the polyolefin feed stream. In some embodiments, the impurities comprise one or more members of the group consisting of polyethylene terephthalate, polystyrene, water, chlorine, or a combination thereof.

[0065] In some embodiments, the process for depolymerizing a polymer further comprises adding a second co-catalyst to the second pyrolysis reaction zone, wherein the second co-catalyst comprises an activated clay component, a solids-based component, or a combination thereof, and wherein the second co-catalyst composition is different from the first co-catalyst composition.

[0066] In some embodiments of the process for depolymerizing a polymer, the first co-catalyst comprises a solid-based component. In some embodiments of the process for depolymerizing a polymer, the first co-catalyst comprises an activated clay component. In some embodiments of the process for depolymerizing a polymer, the second co-catalyst comprises a solid-based component. In some embodiments of the process for depolymerizing a polymer, the second co-catalyst comprises an activated clay component. In some embodiments of the process for depolymerizing a polymer, the first co-catalyst comprises a solid-based component and the second co-catalyst comprises an activated clay co-catalyst. In some embodiments of the process for depolymerizing a polymer, the first co-catalyst comprises an activated clay co-catalyst and the second co-catalyst comprises a solid-based component.

[0067] Some embodiments of the process for depolymerizing a polymer further include adding the second vapor product to a second condensation zone.

[0068] In some embodiments of the process for depolymerizing a polymer, the first depolymerization conditions include a temperature in the range of 250°C to 600°C, 400°C to 600°C, 425°C to 550°C, or 450°C to 550°C, a pressure in the range of 100 kPa to 1,000 kPa, 100 kPa to 700 kPa, 150 kPa to 600 kPa, or 200 kPa to 500 kPa, or a combination thereof.

[0069] In some embodiments of the process for depolymerizing a polymer, the second depolymerization conditions include a temperature in the range of 250°C to 600°C, 250°C to 450°C, 275°C to 425°C, or 300°C to 400°C, a pressure in the range of 100 kPa to 1,000 kPa, 100 kPa to 700 kPa, 150 kPa to 600 kPa, or 200 kPa to 500 kPa, or a combination thereof.

[0070] In some embodiments of the process for depolymerizing a polymer, the first condensation conditions include a temperature in the range of 20° C. to 250° C., 30° C. to 200° C., or 40° C. to 150° C., a pressure in the range of 100 kPa to 200 kPa, 110 kPa to 190 kPa, or 120 kPa to 180 kPa, or a combination thereof.

[0071] In some embodiments of the process for depolymerizing a polymer, the second condensation conditions independently comprise a temperature in the range of 20° C. to 100° C., 30° C. to 90° C., or 40° C. to 80° C., a pressure in the range of 30 kPa to 200 kPa, 50 kPa to 170 kPa, or 70 kPa to 130 kPa, or a combination thereof. Specific Embodiments

[0072] In some embodiments, the polyolefin-based feed stream may be batch processed in the depolymerization unit, as residence time is required for complete depolymerization of the feed stream, with estimated residence times for each batch ranging from 30 minutes to 300 minutes, 40 minutes to 200 minutes, or 50 minutes to 100 minutes, depending on the design of the depolymerization system.

[0073] In some embodiments, the process is operated in a continuous mode. Waste plastic material 201 is fed to a first depolymerization reactor 211. Measures are taken to prevent the introduction of an oxygen-containing atmosphere into the system. The barrier to the oxygen-containing atmosphere can be achieved in various ways, including, but not limited to, a nitrogen blanket system, a vacuum system, or a combination thereof, connected to the extruder barrel. In some embodiments, the plastic mixed waste 201 is loaded into the feed system of the depolymerization reactor 201 using one or more parallel-connected hoppers, and oxygen present in the plastic waste atmosphere is substantially removed in the hopper(s).

[0074] The process according to the present disclosure is very flexible and can feed a variety of plastic waste compositions, such as heterogeneous mixtures of waste plastic materials in which polyolefins are the most abundant component, but which, with additional sorting steps, are uneconomical. In some embodiments, the mixed plastic waste comprises polyethylene, polypropylene, or a combination thereof in an amount of 70% by weight or more, 80% by weight or more, or 90% by weight or more.

[0075] In some embodiments, waste plastic materials undergo a pretreatment step in which they are melted by heat and mixed with additives, which may be alkaline materials. Through melt pretreatment, a heterogeneous mixture of different types of waste plastics can be converted into a homogeneous plastic composite material. The heating temperature in the pretreatment step is appropriately set depending on the type and content of plastics contained in the waste plastic material so as to suppress thermal decomposition of the plastic material being treated. Such temperatures are typically in the range of 100°C to 300°C, preferably 150°C to 250°C.

[0076] At temperatures approaching or exceeding 300°C, HCl is removed from any PVC resin that may be present. If the waste plastic material is mixed with an alkaline material during pre-treatment (melting / kneading), the HCl-generating gas can be removed through an exhaust system and subsequently neutralized or captured. A typical kneader, screw extruder, or the like can be used to perform the melting operation. In some embodiments, the extruder melts the plastic waste material 201 to a high temperature, such as, but not limited to, 250°C to 350°C, and then injects it into the first depolymerization reactor 211. The extruder receives the shredded plastic waste material in a feed hopper and conveys the flow to the melting section, where the polymer is heated by the combined action of mixing energy and heat provided by a barrel heater. Any extrusion system can be used, such as a single-screw extruder, a twin-screw extruder, a twin-screw extruder with a gear pump, or a combination thereof.

[0077] The melt may optionally be compounded with additives to reduce the corrosiveness of the received plastic waste or to improve the conversion process in the reaction section. During extrusion, one or more degassing steps are foreseen to remove residual moisture present in the product. The melt stream may be filtered by mechanical means to remove solid impurities present in the plastic waste before being fed to the first depolymerization reactor 211. Depending on the amount and particle size of the solid particles, several types of melt filtration units can be applied. In some embodiments, the self-cleaning melt filter can be operated for long periods (days) without human intervention to replace the filtration elements.

[0078] In some embodiments, the melt filter is based on a circular perforated plate as the melt filtering element, with holes created by laser or machining, where solids accumulate. The accumulation of impurities can increase the differential pressure across the melt filter. To perform in-line cleaning of the filtering element, a rotating scraper removes the accumulated impurities and directs them from the process to a discharge port that is briefly opened to expel contaminated material.

[0079] This cycle can be repeated for extended periods of time (up to several days) without manual intervention and without the need to stop production for the time required to replace the filtering elements. Another part of the self-cleaning melt filter is based on the application of a continuous band of filtering material through which the polymer flow passes. Impurities accumulate in the metal filter, causing a pressure buildup. The clogged filtering band section is therefore pushed out of the polymer passing area and a clean section is then inserted. This process is automated and can operate for as long as required (up to several days) without manual intervention or the need to stop production for the time required to replace the filtering elements.

[0080] In some embodiments, a process 200 for depolymerizing waste plastic material and producing a thermal product includes feeding a polyolefin-rich waste feed 201 and a first co-catalyst composition 203 in an oxygen-free atmosphere to a feed system comprising a screw extruder, mixer, or other means for heating the extrusion mixture to the melting temperature of the plastic material to create a molten plastic feed stream 201. The first co-catalyst composition 203 comprises a solid base, an activated clay, or a combination thereof.

[0081] In some embodiments, the first promoter composition 203 comprises an activated clay component that is one or more members selected from the group consisting of montmorillonite, sauconite, nontronite, hectorite, beidellite, saponite, bentonite, or a combination thereof, or is a bentonite that includes Na-montmorillonite, Ca-montmorillonite, or a combination thereof.

[0082] In some embodiments, the first promoter composition 203 comprises a solid base component that is one or more members selected from the group consisting of: a) a layered double hydroxide composition; b) an activated carbon composition. In some embodiments, the first promoter composition 203 comprises a solid base component that is one or more members selected from the group consisting of: a) a layered double hydroxide composition; b) an MR composition (where M is an alkali metal, alkaline earth metal, transition metal, post-transition metal, metalloid, or combinations thereof, and R is an oxide, hydroxide, carbonate, sulfate, sulfide, nitrate, nitride, phosphate, phosphite, halide, or combinations thereof); and c) an activated carbon composition. In some embodiments, the layered double hydroxide is hydrotalcite, quintinite, vogelite, woodwardite, quarstivite, wormlandite, hydrocalumite, or combinations thereof, or is hydrotalcite. In some embodiments, the MR composition is Ca(OH)2, Mg(OH)2, Ba(OH)2, Sr(OH)2, CaO, Al2O3, or a combination thereof, or is Ca(OH)2, or a combination thereof.

[0083] The amount of first co-catalyst 203 used in the present method may be limited by the requirements of the depolymerization unit. The first co-catalyst 203 is a solid that contributes to the dead volume within the unit during the depolymerization reaction. The lower the dead volume, the more polymer that can be depolymerized. In some depolymerization units, the amount of first co-catalyst ranges from 0.1 wt % to 20 wt %, 0.2 wt % to 15 wt %, 0.5 wt % to 10 wt %, or 1.0 wt % to 8 wt %, where the weight percentage is based on the total amount of waste plastic 201 and first co-catalyst 203 fed to the first depolymerization reactor 211.

[0084] Care must be taken to avoid introducing an oxygen-containing atmosphere into the system. A barrier to the potentially oxygen-containing atmosphere can be achieved in a variety of ways, such as a nitrogen blanket or a vacuum system connected to the extruder barrel. The molten plastic feed stream is fed to a first depolymerization reactor 211, which is a continuous stirred tank reactor maintained at a temperature ranging from 250°C to 600°C, 400°C to 600°C, 425°C to 550°C, or 450°C to 500°C and operated at a pressure ranging from 100 kPa to 1,000 kPa, 100 kPa to 700 kPa, 150 kPa to 600 kPa, or 200 kPa to 500 kPa, in which depolymerization occurs to form a first gaseous effluent and a first fluid effluent.

[0085] In some embodiments, first depolymerization reactor 211 has a round-bottom cylindrical section with mixer 227, complete with a gear motor, introduced into the longitudinal axis of reactor 211 and rotating the mixer blades to keep the system agitated. Mixer design and motor power can vary depending on reactor contents, volume, and geometry, but as a non-limiting example, mixer 227 may have a 0.2 kW / m 3 ~4kW / m 3 , 0.25kW / m 3 ~2kW / m 3 , or 0.3kW / m 3 ~1.5kW / m 3 It operates over a range of power inputs.

[0086] The first depolymerization reactor 211 is a continuous stirred tank reactor equipped with any equipment connected to the reactor, such as heat exchangers, control valves, temperature and pressure instrumentation, pumps, compressors, etc.

[0087] A first fluid effluent is removed from the first depolymerization reactor 211 via stream 215 to a first lower pump 217. At least a portion of the first fluid effluent is routed to a char handling unit via conduit 223. The remainder of stream 215 is routed to a heater 221 as stream 219 and then returned to the first depolymerization reactor 211 as a heat input medium. In other embodiments (not shown), the liquid slurry portion recycled to the reactor is withdrawn at a point different from the point at which the liquid slurry portion sent to the char handling section is withdrawn. In some embodiments, the liquid slurry is first fed to a dedicated vessel (not shown) with lower and upper outlet points. The liquid portion directed to the char handling section 233 is withdrawn in concentrated form from the lower outlet point, while the liquid portion 219 recycled to the reactor 211 is withdrawn from the upper outlet point.

[0088] In some embodiments, heat exchanger 221 heats stream 219 by heat transfer from a molten salt stream heated to a temperature range of 300-570°C. The molten salt supply circuit (not shown) is configured to prevent leakage of the molten salt. The molten salt is preferably a mixture of sodium nitrate and potassium nitrate, more preferably molten solar salt in a weight ratio ranging from 2:3 to 3:2. The solar salt in turn receives heat from a dedicated furnace, either electric or fuel-fed. In the latter case, a portion of stream 285 from condenser vessel 271 may be used to supply the furnace. Alternatively or in combination, heat may be generated by burning gaseous or liquid hydrocarbons.

[0089] In some embodiments, instead of external heat exchanger 221, the heat associated with the molten salt is preferably transferred to the depolymerization reactor by circulating it through a jacket surrounding the entire reactor and / or by feeding the molten salt to an external heat exchanger, as described below.

[0090] The depolymerization process occurring within the reactor produces molecules with shorter chain lengths and lower boiling points. This continuing destruction of chain length, especially near the reactor walls, produces molecules with smaller and smaller fractions that become gaseous at the operating temperature and pressure.

[0091] The first gaseous effluent from first depolymerization reactor 211 is routed via stream 213 to first condensation vessel 231, from which second gas stream 233 and second liquid stream 235 are produced and withdrawn. In some embodiments of the process for depolymerizing polymer, the first condensation conditions include a temperature in the range of 20° C. to 250° C., 30° C. to 200° C., or 40° C. to 150° C., and a pressure in the range of 100 kPa to 200 kPa, 110 kPa to 190 kPa, or 120 kPa to 180 kPa, or a combination thereof.

[0092] In some embodiments, second gas stream 233 is sent to a second condensation vessel 271, which operates at a lower temperature than first condensation vessel 231. At least a portion of second liquid stream 235 is sent to a second bottom pump 237 and fed as stream 245 to a second depolymerization reactor 251 comprising zeolite catalyst component 207 and, optionally, a second cocatalyst composition 209.

[0093] The zeolite catalyst component is a solid base component that is one or more members selected from the group consisting of ZSM-5 zeolite, beta zeolite, Y zeolite, and ultrastable Y zeolite, or is one or more ultrastable Y zeolites.

[0094] The amount of zeolite catalyst component 207 used in the present process may be limited by the requirements of the depolymerization unit. Zeolite catalyst component 207 is a solid that contributes to the dead volume within the unit during the depolymerization reaction. The lower the dead volume, the more polymer that can be depolymerized. In some depolymerization units, the amount of zeolite catalyst component 207 ranges from 0.1 wt.% to 20 wt.%, 0.2 wt.% to 15 wt.%, 0.5 wt.% to 10 wt.%, or 1.0 wt.% to 8 wt.%, where the weight percentages are based on the total weight of stream 245, zeolite catalyst component 207, and second co-catalyst 209 fed to first depolymerization reactor 251.

[0095] The second promoter composition 209 comprises a solid base, an activated clay, or a combination thereof.

[0096] In some embodiments, the second promoter composition 209 comprises an activated clay component that is one or more members selected from the group consisting of montmorillonite, sauconite, nontronite, hectorite, beidellite, saponite, bentonite, or a combination thereof, or is a bentonite that comprises Na-montmorillonite, Ca-montmorillonite, or a combination thereof.

[0097] In some embodiments, the second promoter composition 209 comprises a solid base component that is one or more members selected from the group consisting of: a) a layered double hydroxide composition; b) an activated carbon composition. In some embodiments, the second promoter composition 209 comprises a solid base component that is one or more members selected from the group consisting of: a) a layered double hydroxide composition; b) an MR composition (wherein M is an alkali metal, alkaline earth metal, transition metal, post-transition metal, metalloid, or combinations thereof, and R is an oxide, hydroxide, carbonate, sulfate, sulfide, nitrate, nitride, phosphate, phosphite, halide, or combinations thereof); and c) an activated carbon composition. In some embodiments, the layered double hydroxide is hydrotalcite, quintinite, vogelite, woodwardite, quarstivite, wormlandite, hydrocalumite, or combinations thereof, or is hydrotalcite. In some embodiments, the MR composition is Ca(OH)2, Mg(OH)2, Ba(OH)2, Sr(OH)2, CaO, Al2O3, or a combination thereof, or is Ca(OH)2, or a combination thereof.

[0098] The amount of second cocatalyst 209 used in the present process may be limited by the requirements of the depolymerization unit. Second cocatalyst 209 is a solid that contributes to the dead volume within the unit during the depolymerization reaction. The lower the dead volume, the more polymer that can be depolymerized. In some depolymerization units, the amount of second cocatalyst ranges from 0.1 wt % to 20 wt %, 0.2 wt % to 15 wt %, 0.5 wt % to 10 wt %, or 1.0 wt % to 8 wt %, where the weight percentages are based on the total weight of stream 245, zeolite catalyst component 207, and second cocatalyst 209 fed to first depolymerization reactor 251.

[0099] In some embodiments, the first promoter component 203 is solids-based and the second promoter component 209 is an activated clay. In some embodiments, the first promoter component 203 is an activated clay and the second promoter component 209 is solids-based.

[0100] In some embodiments, second depolymerization reactor 251 is a continuous stirred tank reactor maintained at a temperature ranging from 250°C to 600°C, 250°C to 450°C, 275°C to 425°C, or 300°C to 400°C and operated at a pressure ranging from 100 kPa to 1,000 kPa, 100 kPa to 700 kPa, 150 kPa to 600 kPa, or 200 kPa to 500 kPa, in which depolymerization occurs to form a first gaseous effluent and a fluid effluent. The remainder of stream 235, if any, is sent to first reflux pump 239 and then routed through cooler 241 and back to first condenser vessel 231 as a gas scrubbing medium.

[0101] In some embodiments, first depolymerization reactor 251 has a round-bottom cylindrical section with mixer 267, complete with a gear motor, introduced into the longitudinal axis of reactor 251 and rotating the mixer blades to keep the system agitated. Mixer design and motor power can vary depending on reactor contents, volume, and geometry, but as a non-limiting example, mixer 267 may have a 0.2 kW / m 3 ~4kW / m 3 , 0.25kW / m 3 ~2kW / m 3 , or 0.3kW / m 3 ~1.5kW / m 3 It operates over a range of power inputs.

[0102] First depolymerization reactor 251 is a continuous stirred tank reactor equipped with any equipment connected to the reactor, such as heat exchangers, control valves, temperature and pressure instrumentation, pumps, compressors, etc.

[0103] A third gaseous waste stream 253 is withdrawn from the second depolymerization reactor 251 and fed to a second condensation unit 271, from which a fourth gas stream 273 and a fourth liquid stream 275 are produced and withdrawn. In some embodiments of the process, the second condensation conditions independently include a temperature in the range of 20° C. to 100° C., 30° C. to 90° C., or 40° C. to 80° C., a pressure in the range of 30 kPa to 200 kPa, 50 kPa to 170 kPa, or 70 kPa to 130 kPa, or a combination thereof.

[0104] In some embodiments, at least a portion of third fluid effluent 255 is recycled to first depolymerization reactor 211 as stream 265. The portion of third fluid effluent 255 in excess of stream 265 is routed to third lower pump 257, where the discharge of third lower pump 257 is routed from heater 261 and then back to first depolymerization reactor 211 as a heat input medium via stream 259, or routed to a char handling unit via stream 263, or a combination thereof.

[0105] In some embodiments, heat exchanger 261 heats stream 259 by heat transfer from a molten salt stream heated to a temperature range of 300-570°C. The molten salt supply circuit (not shown) is configured to prevent leakage of the molten salt. The molten salt is preferably a mixture of sodium nitrate and potassium nitrate, more preferably molten solar salt in a weight ratio ranging from 2:3 to 3:2. The solar salt in turn receives heat from a dedicated furnace, either electric or fuel-fed. In the latter case, a portion of stream 285 from condenser vessel 271 may be used to supply the furnace. Alternatively or in combination, heat may be generated by burning gaseous or liquid hydrocarbons.

[0106] At least a portion of fourth liquid stream 275 is sent to fourth bottom pump 283 for exhausting the heat products from depolymerization processing unit 200. In some embodiments, the remainder of stream 275, if any, is sent to first reflux pump 277 and then routed through cooler 281 back to second condenser vessel 271 as a gas scrubbing medium.

[0107] In some embodiments, the amounts of the first promoter, the second promoter, and the zeolite catalyst component are each independently in the range of 0.1 wt % to 20 wt %, 0.2 wt % to 15 wt %, 0.5 wt % to 10 wt %, or 1.0 wt % to 8 wt %, where the weight percentages are based on the total weight of the waste plastic stream 201, the first promoter component 203, the second promoter component 209, and the zeolite catalyst component 207 used in the process 200. In some embodiments, the composite catalyst system comprises the first promoter 203 and the zeolite catalyst component 207. In some embodiments, the composite catalyst system comprises the second promoter 209 and the zeolite catalyst component 207.

[0108] Depending on the type of depolymerization unit, optional additives such as sand may be added to the mixture of the polyolefin-based feed stream and the composite catalyst. Some of these optional additives may contribute to the dead volume of the depolymerization unit, further limiting the amount of composite catalyst. As an example, screw kiln depolymerization reactors use sand as a heat conductor, which limits the amount of dead volume available for the composite catalyst.

[0109] The presently disclosed composite catalysts and methods for using them to depolymerize polyolefin-based feedstreams are illustrated with reference to the following examples. These examples are included to demonstrate embodiments of the appended claims. However, they are exemplary only, and the present invention is broadly applicable to any combination of polyolefin-based feedstock and composite catalyst, with or without a non-polyolefin component. Those skilled in the art will recognize that many variations can be made to the specific disclosed embodiments with similar results without departing from the spirit and scope of the disclosure herein. The following examples should in no way be read to limit or define the scope of the appended claims. Example

[0110] The following examples are included to demonstrate embodiments of the invention. It should be understood by those of skill in the art that the techniques disclosed in the examples below represent techniques developed by the inventors to function well in the practice of the invention, and as such can be considered to constitute preferred modes for its practice. However, those of skill in the art should, in light of the present disclosure, understand that many changes can be made in the specific embodiments disclosed and still obtain like or similar results without departing from the spirit and scope of the invention. raw materials

[0111] Impure polyolefin feeds ("PBF1" and "PBF2") were used in Examples 1-76 to evaluate the depolymerization performance of certain zeolite catalysts, activated clays, solid bases, or combinations thereof. Polyolefin feed "PBF1" contained a mixture of 5 wt. % ash, 0.9 wt. % water, 0.8 wt. % polystyrene, 0.3 wt. % polyethylene terephthalate, and 0.3 wt. % chlorine, non-polyolefinic components, and approximately equal amounts of post-consumer recycle containing polyethylene and polypropylene in a 1:1 ratio; all weight percentages are based on the total weight of PBF1. Polyolefin feed "PBF2" contained a mixture of 7 wt. % ash, 1 wt. % water, 0.5 wt. % polystyrene, 4 wt. % polyethylene terephthalate, and 0.3 wt. % chlorine, non-polyolefinic components, and approximately equal amounts of post-consumer recycle containing polyethylene and polypropylene in a 1:1 ratio; all weight percentages are based on the total weight of PBF2.

[0112] The zeolite catalysts used herein are shown in Table 1 below. The SiO2 / Al2O3 molar ratio ("SAR") is given for each catalyst. Table 1 [Table 1-1] [Table 1-2]

[0113] The cocatalysts used herein are shown in Table 2 below. Table 2 [Table 2-1] [Table 2-2]

[0114] 1. Contains active Lewis acid and Bronsted acid sites Experimental Process

[0115] Unless otherwise specified, the depolymerization unit was a thermogravimetric analyzer (TGA). For TGA pyrolysis reactions, homogeneous samples were heated under nitrogen in a Mettler Toledo TGA / DSC 3+ (Mettler Toledo, Columbus, OH) at 10 K / min to a depolymerization temperature of 400 °C and held for 1 h. The depolymerization half-life at a specific temperature was defined as the time required to achieve 50% mass loss and was either recorded directly if the value was less than 60 min, or calculated under the assumption of first-order decomposition kinetics. t1 / 2 = 0.693 / k, where k is the first order rate constant plotted against the time chart using Ln(C / C).

[0116] The depolymerization half-life is related to the residence time required in a large-scale depolymerization unit: the shorter the half-life, the shorter the residence time of the polymer feed batch in the depolymerization unit and the faster the depolymerization rate k.

[0117] Samples were prepared by melt compounding with the composite catalyst in a HAAK MiniCTW compounder at 200°C and 200 RPM for 5 minutes. The compositions and their depolymerization half-lives are listed in Tables 3-9. Examples 1 to 4

[0118] Table 3 summarizes the results of Examples 1-4. Each of Examples 1-4 is carried out using a 5 g sample of PBF1. Example 1 provides benchmark data for the depolymerization of PBF1 without a zeolite catalyst, solid-based cocatalyst, or activated clay cocatalyst. Example 2 shows that, compared to Example 1, the depolymerization rate is significantly higher when only activated clay is added. 1 / 2 Example 3 shows that compared to Example 1, when only the solid base was added to the reactor, t 1 / 2 Example 4 shows that compared to Example 1, when solid base and activated clay were added to the reactor, t 1 / 2 This indicates a 34% increase.

[0119] Without wishing to be bound by any particular theory, Example 4 shows that the addition of a solid-based cocatalyst to the reactor reduces the poisoning of the catalytic reaction with the weak acid-activated clay cocatalyst in the reactor, and thus the t 1 / 2 is thought to represent a 25% decrease in Table 3 [Table 3] Examples 5 to 12

[0120] Table 4 summarizes the results of Examples 5-12. Examples 5-12 are each performed using a 5 g sample of PBF1. Example 5 provides benchmark data for the depolymerization of PBF1 in a reactor containing only a beta zeolite catalyst. Example 6, compared to Example 5, demonstrates that the depolymerization rate is significantly higher when only a solids base is added to the reactor. 1 / 2 Example 7 shows that compared to Example 5, when only activated clay was added to the reactor, t 1 / 2 Examples 8-10 show that adding a solid base to the reactor along with the activated clay and zeolite reduces t compared to adding either a solid base (Example 6) or activated clay (Example 7) along with the zeolite catalyst. 1 / 2 Indicates that time is decreasing.

[0121] Without wishing to be bound by any particular theory, it is believed that Examples 11 and 12 do not perform as well as Examples 8-10 because the beta zeolites of Examples 11 and 12 have significantly higher silica-alumina molar ratios ("SAR"). Table 4 [Table 4-1] [Table 4-2] Examples 13 to 23

[0122] Table 5 summarizes the results of Examples 13-23. Each of Examples 13-23 is carried out using a 5 g sample of PBF1. Example 13 provides benchmark data for the depolymerization of PBF1 in a reactor containing only ZSM-5 zeolite catalyst. Example 15 shows, compared to Example 13, that the depolymerization rate was significantly higher when only the solids base was added to the first microreactor. 1 / 2 Example 14 shows that compared to Example 13, when only activated clay was added to the reactor, t 1 / 2 Example 16 shows that adding a solids basis to the reactor in combination with activated clay and the same ZSM-5 zeolite reduces t compared to adding either a solids basis (Example 15) or activated clay (Example 14) with the zeolite catalyst. 1 / 2 Indicates that time is decreasing.

[0123] Although not wishing to be bound by any particular theory, Examples 17 to 23 show that, compared to Example 16, 1 / 2 is thought to show an increasing trend, which correlates with the increase in SAR of these ZSM-5 zeolites. Table 5 [Table 5-1] [Table 5-2] Examples 24 to 44 and 86 to 95

[0124] Table 6 summarizes the results of Examples 24-56 and 86-95. Examples 24-56 and 86-95 were each performed with a 5 g sample of PBF1 and demonstrate the use of 0.1-0.2 g of ultrastable Y (HUSY) zeolite catalyst in the reactor. Examples 24 and 27 provide benchmark data for the depolymerization of PBF1 in a first and second microreactor with only the HUSY zeolite catalyst in the second microreactor. Examples 26, 29-56, and 86-95 demonstrate the improved depolymerization of PBF1 compared to Examples 24 and 27 with the addition of an activated clay cocatalyst to the reactor. 1 / 2 indicates that decreases.

[0125] Without wishing to be bound by any particular theory, it is believed that in Examples 25 and 28, the total amount of catalyst and cocatalyst was low and therefore not sufficient to overcome the adverse effects of impurities in the polyolefin feed. Furthermore, it is believed that in a commercial continuous operation in two reactors in series, the overall results would be improved because pyrolysis in the first reactor and removal of the char waste stream would result in removal of a portion of the catalyst poisons that were removed from the product of the first reactor and then fed to the second reactor. Table 6 [Table 6-1] [Table 6-2] [Table 6-3] [Table 6-4] [Table 6-5] Examples 45 to 51

[0126] Table 7 summarizes the results of Examples 45-51. Examples 24 and 27 are copied from Table 6 and provide benchmark data for the depolymerization of PBF1 in the first and second microreactors with only HUSY zeolite catalyst in the reactor. Examples 45-51 were each performed with a 5 g sample of PBF1 and demonstrate the use of various amounts of different solids bases in the first microreactor and the use of 0.2 g of HUSY zeolite catalyst in the reactor. Examples 45-47 and 49-51 all demonstrate significantly improved depolymerization rates compared to Examples 24 and 27 due to the absence of the clay component. 1 / 2 The time is shown to be substantially reduced.

[0127] Without wishing to be bound by any particular theory, it is clear that Example 48 exhibited a significantly improved t 1 / 2 It is believed that the increase in % is due to the need for a clay component, along with a specific solids base, to achieve the desired effect. Furthermore, it is believed that in a commercial continuous operation in two reactors in series, the results would all be improved because pyrolysis in the first reactor and removal of the char waste stream would result in removal of a portion of the catalyst poisons removed from the product of the first reactor and then fed to the second reactor. Table 7 [Table 7] Examples 52 to 69 and 96

[0128] Table 8 summarizes the results of Examples 52-69, and 96. Each of Examples 52-69, and 96 was performed using a 5 g sample of PBF1 and demonstrates the use of various amounts of different solid bases in the reactor and the use of 0.1 g to 0.3 g of HUSY zeolite catalyst in the reactor. Compared to the results in Table 6 (HUSY zeolite and activated clay in the reactor) and Table 7 (HUSY zeolite in the reactor along with the solid base), Examples 52-69, and 96 in Table 8 (HUSY zeolite and activated clay in the second microreactor in addition to the solid base in the reactor) demonstrate that the use of both cocatalysts results in a significantly higher t than the use of either cocatalyst individually. 1 / 2 This indicates that time is tending to decrease.

[0129] Examples 55, 57, and 61 show that for HUSY zeolite used in combination with both cocatalysts, 1 / 2 However, Examples 55 (activated carbon as solids basis) and 57 (hydrotalcite as solids basis) had t times of 45 minutes and 44.7 minutes, respectively. 1 / 2 Examples 47 (activated carbon as solids basis) and 48 (hydrotalcite as solids basis) in Table 7 had t times of 99.0 and 108.3 minutes, respectively. 1 / 2 Therefore, compared to a similar type of solid base, the addition of activated clay cocatalyst to the second microreactor significantly improved the t 1 / 2 Example 61 (halloysite as the activated clay) showed a greater t than Example 29 in Table 6. 1 / 2 Although time is indicated, in commercial continuous operation with two reactors in series, it is believed that the use of a solid base in the first reactor in combination with halloysite in the second reactor will result in better conversion than that produced in a microreactor, since removing a char waste stream from the first reactor will result in the removal of some of the catalyst poisons that were removed from the product of the first reactor and then fed to the second reactor. Table 8 [Table 8-1] [Table 8-2] [Table 8-3] Examples 70 to 73

[0130] Table 9 summarizes the results of Examples 70-73. Each of Examples 70-73 was performed using a 5 g sample of PBF1 and demonstrates the use of 0.2 g of a number of different Y zeolite catalysts with both activated clay and solid base in the reactor. Again, with the use of both cocatalysts, these various Y zeolites perform similarly to other zeolites used in combination with both cocatalysts. Table 9 [Table 9] Examples 74 to 76

[0131] Table 10 summarizes the results of Examples 74-76. Examples 74-76 were performed using a Frontier Lab Tandem Microreactor System (Model No. Rx-3050TR) connected to an Agilent GC / MS (Model Nos. 8890 and 5977). The feed used in Examples 74-76 was Feed PBF2. The zeolite used in these examples was HUSY (CFG-1). The activated clay used in these examples was Bentonite F20X. The solid base used in these examples was Ca(OH)2.

[0132] These examples demonstrate the value of co-catalyst staging with a system using two pyrolysis reactors in series. The first microreactor was operated at a temperature of 500°C and a pressure of 13 psig. The second microreactor was operated at a temperature of 300°C and a pressure of 13 psig.

[0133] Example 74 shows depolymerization conversion performance using only the zeolite catalyst in the second reactor. Example 75 shows improved depolymerization conversion performance over that of Example 74 achieved by adding an activated clay and solid-based cocatalyst to the first reactor in combination with the zeolite catalyst in the second reactor. Example 76 shows even improved depolymerization conversion performance over that of Example 75 achieved by adding only the solid-based cocatalyst to the first reactor in combination with the activated clay and zeolite catalyst in the second reactor. Table 10 [Table 10]

[0134] Figure 3 shows a graphical comparison of Examples 74-76 under the conditions described above and shown in Table 10. Catalyst efficiency was measured by the level of propylene trimer in the product stream, with lower values ​​of propylene trimer content correlating with higher levels of catalytic activity and higher values ​​of propylene trimer content correlating with lower levels of catalytic activity. Measured propylene trimer content, calculated as a percentage (%) of the total mass spectrometry (MS) area for the first 30 minutes of the run, for Examples 74-76 is shown as the y-axis values ​​in Figure 3. Effective catalyst life is indicated by the amount of waste plastic processed per unit of zeolite catalyst. The weight of feed per weight of catalyst measurement for Examples 74-76 is shown as the x-axis values ​​in Figure 3.

[0135] Comparing Example 75 with Example 74 shows that adding clay and base promoters improves both catalyst life and catalytic efficiency. Comparing Example 76 with Example 75 shows that adding the base promoter before the clay promoter further improves both catalyst life and catalytic efficiency. Examples 77 to 84 Ingredients for Examples 77 to 84

[0136] An impure, post-consumer polyolefin feed ("PBF3") was used in Examples 80-87 to evaluate the depolymerization performance of certain activated clays. Polyolefin feed "PBF3" contained approximately 97% by weight of a 30 / 70 weight ratio blend of polypropylene and polyethylene (PP:PE), with the remainder containing trace amounts of other common polymers (polyethylene terephthalate, polystyrene, polyamide, and polyurethane) and inorganic contaminants. Experimental Processes for Examples 77 to 84

[0137] 30 g of PBF3 was placed in a 500 mL three-neck round-bottom glass reactor equipped with a thermocouple and a nitrogen inlet. In each of Examples 77-84, 2.5 wt. % of a solid catalyst, HY zeolite catalyst (CBV400, Zeolyst International), based on the weight of PBF3, was added to the reactor. In each of Examples 78-84, 2.5 wt. % of a cocatalyst (shown in Table 12), based on the weight of PBF3, was also added to the reactor. Two glass condensers were connected in series to the three necks of the reactor and maintained at 110 °C and -8 °C, respectively, using an oil bath (Cryostat Julabo). The reactor was placed in an electric heating system (i.e., a mantle bath). The sample was heated under nitrogen to the depolymerization temperature of 430 °C at 10 K / min and held for 2 h. Table 12 [Table 11]

[0138] The pyrolysis oil, gaseous products, and solid residue remaining in the reactor were then collected and measured. Table 12 summarizes the efficiency of the cocatalysts as a percentage reduction in solid residue, normalized to the results of Example 77. As can be seen from Table 12, the systems containing Fulcat 435, Tonsil Supreme 115FF, and M300UF cocatalysts provided the greatest reduction in residual solids. Example 85

[0139] The following experimental steps were carried out in a depolymerization apparatus consisting of two reactors connected in series, each consisting of a mechanically stirred vessel (and a heating jacket). The first reactor had an inlet for plastic waste fed from an extruder and an outlet for the produced gas. The gas extracted from the reactor was sent to a condenser, from which non-condensable gas and pyrolysis oil were obtained. A thermocouple was placed in the reactor to monitor and record the temperature. The oil collected from the condensation unit was fed to a second depolymerization reactor, which also had an inlet for catalyst feeding. The catalyst was fed to the reactor as a solid slurry by mixing it with a portion of the same oil from the condensation section.

[0140] The second reactor is also equipped with an outlet line for recycling a portion of the reactor contents to the first depolymerization reactor.

[0141] The polyolefin feed "PFB4" contains a blend of post-consumer PE and PP in a 2:1 weight ratio with the following polyolefin components: 8 wt% ash, 1 wt% polystyrene, and 1 wt% nylon 6, all weight percentages based on the total weight of PBF4.

[0142] The PBF4 feedstock was homogenized and pelletized before being loaded into a hopper required to feed an extruder operating at 290°C, which continuously discharged the feedstock into the depolymerization reactor at 4 kg / h. The first depolymerization reactor was operated at a pressure of 4 barg and a temperature of approximately 412°C, with an average residence time of approximately 192 minutes. The gas phase of the reactor was sent to a condensation unit formed by a cooling / washing tower operating at 80°C and a dephlegmator operating at 25°C. The oil stream was then added to a second vessel operating at 335°C and 5.5 barg. The average residence time in this case was approximately 138 minutes. Equal amounts of H-USY zeolite type (CFG-1, Zeolyst International) and activated clay (Fulcat 435, BYK USA Inc.) samples were tested in this second reactor. The catalyst mixture was fed to the pyrolyzer in an amount equivalent to 6 wt. % of the mass of the reaction phase. Table 11 [Table 12]

[0143] Rx1 T(℃)=Reactor 1 - Pyrolysis temperature PFG Rx1 p(barg) = Reactor 1 - Pyrolysis pressure Rx1 tau (min) = Reactor 1 - Pyrolysis residence time Rx2 T(℃)=Reactor 2 - Thermal decomposition temperature Rx2 p(barg) = Reactor 2 - Pyrolysis pressure Rx2 tau (min) = Reactor 2 - Pyrolysis residence time Solid (wt%) = Residue in the reactor relative to the raw material Pyoil (wt%) = Liquid yield relative to raw material Gas (wt%) = gas yield relative to raw material Table 11 summarizes the process conditions and Example 85, which shows that the product contains 54 wt. % pyoil, 35 wt. % gaseous products, and 11 wt. % solids.

[0144] For brevity, only certain ranges are explicitly disclosed herein. However, in addition to the recited ranges, any lower limit may be combined with any upper limit to recite a range not expressly stated; similarly, a range from any lower limit may be combined with any other lower limit to recite a range not expressly stated; similarly, a range from any upper limit may be combined with any other upper limit to recite a range not expressly stated. Furthermore, a range includes every point or individual value between its endpoints, even if not explicitly recited. Thus, every point or individual value may be combined with any other point or individual value, or with other lower or upper limits, to serve as its own lower or upper limit, to recite a range not expressly stated.

[0145] While the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the invention, as defined by the appended claims. Moreover, the scope of this application is not intended to be limited to the particular embodiments of the processes, machines, means, methods, and / or steps described in the specification. As will be readily apparent from this disclosure, those skilled in the art can utilize, in accordance with the present invention, currently existing or later-developed processes, compositions, machines, methods, and / or steps that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, means, methods, and / or steps.

Claims

1. 1. A catalyst system for depolymerizing a polymer, said catalyst system comprising: a) a zeolite catalyst component; b) a co-catalyst comprising an activated clay component, a solid base component, or a combination thereof.

2. 10. The catalyst system of claim 1, wherein the zeolite catalyst component is one or more members selected from the group consisting of ZSM-5 zeolite, beta zeolite, Y zeolite, and ultrastable Y zeolite.

3. The zeolite catalyst component is a SiO in the range of 200:1 to 1:1 ２ / Al ２ O ３ 10. The catalyst system of claim 1 having a molar ratio of:

4. 10. The catalyst system of claim 1, wherein the activating clay component is one or more members selected from the group consisting of montmorillonite, sauconite, nontronite, hectorite, beidellite, saponite, bentonite, or combinations thereof.

5. the solid base component is a) a layered double hydroxide composition; b) an activated carbon composition; and c) a catalyst system according to claim 1 .

6. 6. The catalyst composition of claim 5, further comprising an MR composition, wherein M is an alkali metal, alkaline earth metal, transition metal, post-transition metal, metalloid, or combination thereof, and R is an oxide, hydroxide, carbonate, sulfate, sulfide, nitrate, nitride, phosphate, phosphite, halide, or combination thereof.

7. 1. A process for depolymerizing a polymer, said process comprising: a) adding a polyolefin-based feed stream and a first co-catalyst to a first pyrolysis reaction zone to form a first reaction mixture, wherein the first co-catalyst comprises an activated clay component, a solids-based component, or a combination thereof; b) reacting the first reaction mixture under first depolymerization conditions in the absence of oxygen to form a first vapor stream and a first liquid stream comprising char; c) adding the first vapor stream to a first condensing zone, wherein the first vapor stream is passed through condensing conditions to form a second vapor stream and a second liquid stream; d) adding the second liquid stream and a zeolite catalyst component to a second pyrolysis reaction zone to form a second reaction mixture; e) reacting the second reaction mixture under second depolymerization conditions in the absence of oxygen to form a third vapor stream and a third liquid stream comprising char; f) adding said third vapor stream to a second condensing zone, wherein said third vapor stream is passed through condensing conditions to form a fourth vapor stream and a fourth liquid stream, said second liquid product comprising one or more olefin monomers.

8. 8. The process of claim 7, wherein the polyolefin feed stream comprises polyethylene, polypropylene, or a combination thereof.

9. 8. The process of claim 7, wherein said polyolefin feed stream comprises 20 wt. % impurities, said weight percent being based on the total weight of said polyolefin feed stream.

10. 10. The process of claim 9, wherein the impurities comprise one or more members of the group consisting of polyethylene terephthalate, polystyrene, water, chlorine, or combinations thereof.

11. 8. The process of claim 7, further comprising adding a second cocatalyst to the second pyrolysis reaction zone, wherein the second cocatalyst comprises an activated clay component, a solids-based component, or a combination thereof, and wherein the second cocatalyst composition is different from the first cocatalyst composition.

12. The process of claim 7 wherein the first promoter comprises a solid base component.

13. 8. The process of claim 7, wherein the first promoter comprises an activated clay component.

14. The process of claim 11 , wherein the second promoter comprises a solid base component.

15. The process of claim 11 , wherein the second promoter comprises an activated clay component.

16. 8. The process of claim 7, further comprising adding the second vapor product to the second condensing zone.

17. 8. The process of claim 7, wherein the first depolymerization conditions comprise a temperature in the range of 400°C to 600°C, a pressure in the range of 1.0 barg (100 kPa) to 7.0 barg (700 kPa), or a combination thereof.

18. 8. The process of claim 7, wherein the second depolymerization conditions comprise a temperature in the range of 250°C to 450°C, a pressure in the range of 1.0 barg (100 kPa) to 7.0 barg (700 kPa), or a combination thereof.

19. 8. The process of claim 7, wherein the first condensation conditions comprise a temperature in the range of 20°C to 250°C, a pressure in the range of 1.0 barg (100 kPa) to 2.0 barg (200 kPa), or a combination thereof.

20. 8. The process of claim 7, wherein the second condensation conditions independently comprise a temperature in the range of 20°C to 250°C, a pressure in the range of 0.3 barg (30 kPa) to 2.0 barg (200 kPa), or a combination thereof.

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