Compositions and methods for the degradation of waste polypropylene

Abstract

A method for the degradation of polypropylene is disclosed. Also disclosed are products obtained from the degraded polypropylene, including carboxylic acids, dicarboxylic acids, nitro-substituted carboxylic acids, and nitro-substituted dicarboxylic acids, as well as their salts, esters, and anhydrides.

Description

[Technical Field]

[0001] The present invention relates to the field of decomposition and recycling of plastic waste. More specifically, the present invention includes a method for decomposing polypropylene (PP) and products obtained by decomposition of PP, including carboxylic acids, dicarboxylic acids, nitro-substituted carboxylic acids, nitro-substituted dicarboxylic acids, and their salts, esters, and anhydrides. [Background technology]

[0002] All publications in this specification are incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. The following description contains information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the present invention, or that any publication specifically or implicitly referenced is prior art.

[0003] Plastic pollution is a global environmental crisis for many reasons. Plastics are designed to be durable, not degradable. Those designed to be biodegradable present drawbacks, such as high production costs and performance issues, which make them challenging to produce or use on a large scale. Furthermore, the existence of a wide variety of plastic polymers increases public confusion about what can be recycled. Plastic consumerism is inevitable and continues to expand. Not only is existing plastic pollution pervasive and ubiquitous, but new plastic waste is being generated at an alarming rate. This global plastic waste surplus harms the environment and contaminates the food chain.

[0004] Common components found in municipal waste streams and marine debris are contaminated Plastic or contaminated plastic waste. Current methods for treating contaminated plastic or contaminated plastic waste include pyrolysis, incineration, landfill disposal, and mechanical recycling after thorough cleaning. Pyrolysis of plastic is energy intensive, and the fuels produced are low-grade and require expensive refining steps to convert them into useful chemicals. This is not economically feasible. Incineration of plastic requires a large upfront investment to establish, requires significant power and maintenance, and, like landfill disposal of plastic, has harmful environmental consequences. These expensive methods pollute the environment and do not utilize contaminated plastic waste material that could be used as a feedstock for new products. Nearly all post-consumer and post-industrial contaminated plastic waste is collected at material recovery facilities, where it may become further contaminated. Mechanical recycling for many plastics is not economically viable because recycled plastic resins are often of poor quality and cannot compete with cheaper virgin plastics.

[0005] Less than 10% of the plastic produced worldwide is recycled because the process is uneconomical. As much as 50% of the contents of recycling bins in the United States are thought to be contaminated and are typically discarded through conventional recycling processes. Although plastic is the most abundant material in the waste recovery stream, with the exception of water bottles, most plastics have few or no viable downstream markets, making them the least preferred materials for recycling.

[0006] Although much research has been done on the bioremediation of plastic pollution, biological methods alone are expensive, inefficient, and difficult to scale. Such technologies, including ex vivo cell degradation or digestion by insect larvae, have yet to link plastic waste treatment with the production of economically value-added products.

[0007] Polypropylene (PP) is one of the most common packaging materials used in the United States due to its melting point and high strength. In 2017, approximately 8% of PP plastic generated in the United States was recycled. There are several reasons for PP's low recycling rate, including the high cost of recycling, the relatively low cost of virgin PP, and the reduced quality of recycled PP compared to virgin.

[0008] There are two main categories of recycling techniques currently used to recycle PP. Mechanical recycling techniques clean the polymer and create new PP raw materials that can be used to manufacture new products. The basic mechanical recycling process involves several steps, which may include collection, sorting, cleaning, melt processing, and the formation of new materials. In some cases, solvent-based separation procedures are implemented to remove impurities from post-consumer plastics. See WO2012 / 117250A1, WO2017 / 003802A1, and WO2008 / 058303A1. PP is often subjected to harsh conditions during mechanical recycling, resulting in a downgraded PP compared to virgin PP.

[0009] Chemical recycling techniques are also currently used to convert post-consumer PP into fuel or energy. See WO2014 / 040634A1 and WO2016 / 091993A1. Such techniques are typically energy intensive and result in low carbon efficiency.

[0010] Therefore, there is a need in the art for methods and systems that provide for the degradation of PP waste that overcome the limitations of known methods. Summary of the Invention

[0011] The following embodiments and aspects thereof are described and illustrated in conjunction with compositions and methods that are intended to be exemplary and illustrative rather than limiting in scope.

[0012] 1. A method for decomposing polypropylene (PP) waste, comprising: a. adding PP waste to a reaction vessel; b. adding at least one oxidizing agent to a reaction vessel to provide a mixture; c. subjecting the mixture obtained in b. to conditions effective to decompose the PP waste to produce decomposition products, wherein the decomposition products comprise at least one dicarboxylic acid optionally substituted with a nitro group, or a salt or ester or anhydride thereof; A method is provided, comprising:

[0013] In one embodiment, the degradation products further comprise at least one carboxylic acid optionally substituted with a nitro group.

[0014] In one embodiment, the PP waste further comprises at least one plastic material and at least one non-plastic material. In another embodiment, the plastic material comprises at least one selected from the group consisting of plastic film, plastic foam, plastic packaging, plastic bags, plastic wrap, and combinations thereof. In another embodiment, the non-plastic material comprises at least one selected from the group consisting of non-plastic organic materials, inorganic materials, fluids, and combinations thereof.

[0015] In some embodiments, the at least one oxidizing agent is oxygen (O), nitric oxide (NO), nitrous oxide (NO), nitrogen dioxide (NO), nitric acid (HNO), aqueous nitric acid (HNO), or a combination thereof. In one embodiment, the at least one oxidizing agent is aqueous nitric acid (HNO). In another embodiment, the nitric acid has a concentration of 10 to 100 wt%. In one embodiment, the nitric acid has a concentration of about 67 to about 70 wt%.

[0016] In some embodiments, the weight ratio of nitric acid to PP is at least 3: 1. In one embodiment, the weight ratio of nitric acid to PP is at least 10: 1. In another embodiment, the weight ratio of nitric acid to PP is 10-100: 1.

[0017] In one embodiment, the conditions include a temperature range of 60°C to 200°C. In another embodiment, the conditions include an initial pressure range of 0 psi to 1000 psi. In another embodiment, the conditions include the presence of at least one gas selected from air, nitrogen (N2), oxygen (O2), or a combination thereof. In another embodiment, the conditions include a residence time in the reaction vessel of 30 minutes to 30 hours.

[0018] In one embodiment, the dicarboxylic acid or the dicarboxylic acid substituted with at least one nitro group is substituted with one or more methyl groups.

[0019] In one embodiment, the degradation product is at least one C4-C 15 In another embodiment, the degradation product comprises at least one C4-C9 dicarboxylic acid. In another embodiment, if the dicarboxylic acid comprises an even-numbered n carbon chain between the two carboxy groups, it is substituted with (n / 2)-1 methyl groups. In another embodiment, if the dicarboxylic acid comprises an odd-numbered n carbon chain between the two carboxy groups, it is substituted with (n / 2)-1 or (n / 2)-2 methyl groups.

[0020] In one embodiment, the degradation products resulting from the method include at least one of 2-methylsuccinic acid, 3-methylglutaric acid, 2,4-dimethylglutaric acid, 2,4-dimethyladipic acid, 3,5-dimethylpimelic acid, 2,4,6-trimethylpimelic acid, 2,4,6-trimethylsebacic acid, and 2,4,6,8-tetramethylazelaic acid. In another embodiment, the degradation product is methylbutanedioic acid dimethyl ester, methylbutanedioic acid dimethyl ester, methylbutanedioic acid dimethyl ester, 2,4-dimethylpentanedioic acid dimethyl ester, 2-formyl-1H-1,4-benzenedicarbonitrile, 2,4-dimethylpentanedioic acid dimethyl ester, 5-acetoxy-3-methylhexanoic acid methyl ester, (R,R)-(−)-2,4-dimethyl-9-decenoic acid methyl ester, 2-methylheptanedioic acid dimethyl ester, 3,5-dimethylheptanedioic acid dimethyl ester, 2-butylquinoline, cyclohexanecarboxylic acid ethyl ester, 3-cyclobut-1-enyl-hydroxy-2-methylpropionic acid methyl ester, adipic acid methyl propyl ester, 2-methyl-3-cyclopropylpropanoic acid methyl ester, and further comprising at least one of 1-cyclopentyl-3-ethoxy-2-propanone, cis-1,2-diethylcyclohexane, 1,2-diethyl-3-methylcyclohexane, 2,2,7,7-tetramethyloctanedioic acid, (2S,4R)-(+)-2,4-dimethyl-9-decenoic acid methyl ester, O-fluoroacetophenone oxime, dibenzo[b,f]oxepin-3-ylamine, (4-ethoxyphenyl)carbamic acid ethyl ester, 2-(1-methyl-1H-imidazol-4-yl)quinoline, 2,8-bis(1,5,5-trimethylpyrrolidine-2,4-dione-3-ylidene)-3,7-diazanonane, 2-amino-3,5,7,8-tetrahydro-4,6-pteridinedione, or 1,2-dimethoxy-4-(1,2-dimethoxyethyl)benzene.

[0021] In one embodiment, the carboxylic acid or dicarboxylic acid resulting from the process is substituted with at least one nitro group. In another embodiment, the carboxylic acid or dicarboxylic acid is substituted with a nitro group at the 2-position. In another embodiment, the carboxylic acid or dicarboxylic acid is substituted with a nitro group at the 3-position. In another embodiment, the carboxylic acid or dicarboxylic acid is substituted with a nitro group at an internal position.

[0022] In one embodiment, the method further comprises adding at least one solid catalyst to the reaction vessel. In another embodiment, the at least one solid catalyst is selected from the group consisting of zeolites, alumina, silicoaluminophosphates, sulfated zirconia, zinc oxide, titanium oxide, zirconium oxide, niobium oxide, iron carbonate, calcium carbide, and combinations thereof.

[0023] In one embodiment, the method further comprises separating the decomposition products into a solid phase and a liquid phase. In another embodiment, the solid phase comprises at least one selected from the group consisting of an oligomer, a polymer, and combinations thereof. In another embodiment, the solid phase further comprises at least one solid catalyst.

[0024] In one embodiment, the liquid phase comprises a carboxylic acid, a dicarboxylic acid, a nitro-substituted carboxylic acid, or a nitro-substituted dicarboxylic acid, or a salt or ester or anhydride thereof.

[0025] In one embodiment, the method further comprises converting the carboxylic acid optionally substituted with a nitro group and / or the dicarboxylic acid optionally substituted with a nitro group to an ester.

[0026] In one embodiment, the method further comprises isolating a carboxylic acid optionally substituted with a nitro group and / or a dicarboxylic acid optionally substituted with a nitro group, or a salt, ester, or anhydride thereof. In another embodiment, the method further comprises isolating at least one corresponding ester. In one embodiment, the ester is at least one of 2-methylsuccinic acid dimethyl ester, 3-methylglutaric acid dimethyl ester, 2,4-dimethylglutaric acid dimethyl ester, 2,4-dimethyladipic acid dimethyl ester, 3,5-diethylpimelic acid dimethyl ester, 2,4,6-trimethylpimelic acid dimethyl ester, 4,6-trimethylsebacic acid dimethyl ester, 2,4,6,8-tetramethylazelaic acid, or a combination thereof.

[0027] In one embodiment, the method further comprises returning the oligomer, polymer, and combinations thereof to the reaction vessel.

[0028] In one embodiment, the liquid phase further comprises at least one oxidant. In another embodiment, the method further comprises collecting and regenerating the at least one oxidant.

[0029] Also provided are compositions comprising 2-methylsuccinic acid, 3-methylglutaric acid, 2,4-dimethylglutaric acid, 2,4-dimethyladipic acid, 3,5-dimethylpimelic acid, 2,4,6-trimethylpimelic acid, 2,4,6-trimethylsebacic acid, and 2,4,6,8-tetramethylazelaic acid, or salts or esters or anhydrides thereof. In one embodiment, the composition comprises methylbutanedioic acid dimethyl ester, methylbutanedioic acid dimethyl ester, methylbutanedioic acid dimethyl ester, 2,4-dimethylpentanedioic acid dimethyl ester, 2-formyl-1H-1,4-benzenedicarbonitrile, 2,4-dimethylpentanedioic acid dimethyl ester, 5-acetoxy-3-methylhexanoic acid methyl ester, (R,R)-(-)-2,4-dimethyl-9-decenoic acid methyl ester, 2-methylheptanedioic acid dimethyl ester, 3,5-dimethylheptanedioic acid dimethyl ester, 2-butylquinoline, cyclohexanecarboxylic acid ethyl ester, 3-cyclobut-1-enyl-hydroxy-2-methylpropionic acid methyl ester, adipic acid methyl propyl ester, methyl 2-methyl-3-cyclopropylpropanoate, 1-cyclopentyl-3-ethoxy-2-propanone, cis-1,2-di Ethylcyclohexane, 1,2-diethyl-3-methylcyclohexane, 2,2,7,7-tetramethyloctanedioic acid, (2S,4R)-(+)-2,4-dimethyl-9-decenoic acid methyl ester, O-fluoroacetophenone oxime, trans-2-(1-mercapto-1-methylethyl)-5-methylcyclohexanone, dibenzo[b,f]oxepin-3-ylamine, (4-ethoxyphenyl)ethylcarbamate ester, 2-(1-methyl-1H-imidazol-4-yl)quinoline, 2,8-bis(1,5,5-trimethylpyrrolidine-2,4-dione-3-ylidene)-3,7-diazanonane, 2-amino-3,5,7,8-tetrahydro-4,6-pteridinedione, or 1,2-dimethoxy-4-(1,2-dimethoxyethyl)benzene, or a salt or ester or anhydride thereof. DETAILED DESCRIPTION OF THE INVENTION

[0030] Detailed Description of the Invention All references cited herein are incorporated by reference in their entirety as if fully set forth. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0031] Those skilled in the art will recognize many methods and materials similar or equivalent to those described herein, which could be used in the practice of the present invention. Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, various features of embodiments of the present invention. Indeed, the present invention is in no way limited to the methods and materials described. For convenience, certain terms employed in the specification, examples, and appended claims are collected here.

[0032] Unless otherwise stated or clear from the context, the following terms and phrases include the meanings provided below. Unless otherwise stated or clear from the context, the following terms and phrases do not exclude the meaning that the term or phrase has acquired in the art to which it pertains. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should be understood that the present invention is not limited to the particular methodology, protocols, reagents, etc. described herein, and as such may vary. The definitions and terminology used herein are provided to aid in the description of particular embodiments and are not intended to limit the claimed invention, since the scope of the present invention is limited only by the claims.

[0033] As used herein, the term "comprising" or "comprises" is used in reference to compositions, methods, systems, articles of manufacture, and their respective component(s) that are useful in the embodiments, but does not preclude the inclusion of unspecified elements, whether useful or not. As will be understood by those skilled in the art, in general, the terms used herein are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including, but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "including, but not limited to," etc.). As used herein, the term "comprising" or "comprises" means that in addition to the presented, defined elements, other elements may also be present. The use of "comprising" indicates inclusion rather than limitation. The open-ended term "comprising" is used herein to describe and claim the present invention as synonymous with terms such as including, containing, or having, although the present invention or embodiments thereof may alternatively be described using alternative terms such as "consisting of" or "consisting essentially of."

[0034] Unless otherwise stated, the terms “a,” “an,” and “the,” and similar references, when used in the context of describing particular embodiments of this application (particularly in the context of the claims), can be construed to cover both the singular and the plural. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise stated herein, each individual value is incorporated herein as if set forth individually herein. All methods described herein can be performed in any suitable order unless otherwise stated herein or clearly contradicted by context. Any use of examples or illustrative language (e.g., “such as”) provided herein with respect to particular embodiments is intended merely to clarify the application and does not pose a limitation on the scope of the claimed application. The abbreviation “eg,” derived from the Latin exempli gratia, is used herein to indicate a non-limiting example. Thus, the abbreviation "eg" is synonymous with the term "for example." No language in the specification should be construed as indicating any non-claimed element essential to the practice of the application.

[0035] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. The members of each group may be referred to and claimed individually or in any combination with other members of the group or other elements described herein. One or more members of a group may be included in or deleted from a group for reasons of convenience and / or patentability. When such inclusion or deletion occurs, the specification shall be deemed to contain the group as modified and thus fulfill all Markush group descriptions used in the appended claims.

[0036] "Optional" or "optionally" means that the subsequently described circumstance may or may not occur, and thus the description includes instances in which the circumstance occurs and instances in which it does not occur.

[0037] As used herein, the term "substituted" refers to the independent replacement of one or more (typically 1, 2, 3, 4, or 5) hydrogen atoms on the moiety being substituted with a substituent independently selected from the group of substituents listed below in the definition of "substituent" or as otherwise specified. In general, a non-hydrogen substituent can be any substituent that can be bonded to an atom of the given moiety that is specified to be substituted. Examples of the substituent include acyl, acylamino, acyloxy, aldehyde, alicyclic, aliphatic, alkanesulfonamido, alkanesulfonyl, alkaryl, alkenyl, alkoxy, alkoxycarbonyl, alkyl, alkylamino, alkylcarbanoyl, alkylene, alkylidene, alkylthio, alkynyl, amide, amido, amino, amidine, aminoalkyl, aralkyl, aralkylsulfonamido, arenesulfonamido, arenesulfonyl, aromatic, aryl, arylamino, arylcarbanoyl, aryloxy, azide, carbamoyl, carbonyl, ketone, and the like. Examples of substituents include, but are not limited to, carbonyls, including ketones, carboxy, carboxylates, CF3, cyano (CN), cycloalkyl, cycloalkylene, ester, ether, haloalkyl, halogen, heteroaryl, heterocyclyl, hydroxy, hydroxyalkyl, imino, iminoketone, ketone, mercapto, nitro, oxaalkyl, oxo, oxoalkyl, phosphoryl (including phosphonate and phosphinate), silyl groups, sulfonamide, sulfonyl (including sulfate, sulfamoyl, and sulfonate), thiols, and ureido moieties, each of which may also be optionally substituted or unsubstituted. In some cases, two substituents, together with the carbon(s) to which they are attached, may form a ring. In some cases, two or more substituents, together with the carbon(s) to which they are attached, may form one or more rings.

[0038] Substituents may be protected as necessary using any of the protecting groups commonly used in the art. Non-limiting examples of protecting groups can be found, for example, in Greene and Wuts, Protective Groups in Organic Synthesis, 44th Ed., Wiley & Sons, 2006.

[0039] The term "carboxy" refers to the radical -C(O)O-. It should be noted that compounds described herein containing a carboxy moiety may include protected derivatives thereof, i.e., those in which the oxygen is replaced with a protecting group. Suitable protecting groups for a carboxy moiety include benzyl, tert-butyl, methyl, ethyl, and the like. The term "carboxyl" refers to -COOH.

[0040] The term "polymer" refers to a substance, compound, or mixture of compounds having a molecular structure consisting primarily or entirely of many similar units (e.g., monomeric units) linked together, including linear polymers, also called straight-chain because they consist of long strings of carbon-carbon bonds; branched polymers have branches at irregular intervals along the polymer chain; crosslinked polymers contain branches that connect the polymer chains via covalent, ionic, or H-bonds; and optionally substituted polymers are polymers containing functionality at random points along the hydrocarbon chain backbone, where one or more of the hydrogen atoms linked to the chain backbone may, but need not, be substituted with a substituent independently selected from the group of substituents provided in the definition of "substituent" herein or as otherwise specified. Such polymers are generally said to be optionally substituted because they do not exhibit a regular substitution pattern along the backbone of the chain; addition polymers are formed by adding a monomer to a growing polymer chain; condensation polymers are formed when a small molecule condenses out during a polymerization reaction; homopolymers are formed by polymerizing a single monomer; copolymers are formed by polymerizing two or more monomers; synthetic polymers are synthesized through chemical reactions; natural polymers are derived from nature and can be extracted; biopolymers are produced by organisms and are modified or natural; and organic polymers are polymers that contain carbon atoms in the backbone of the polymer chain.

[0041] The term "oligomer" refers to a substance, compound, or mixture of compounds having a molecular structure that consists primarily or entirely of a small number of similar units (e.g., monomeric units) joined together.

[0042] The term "plastic" refers to synthetic materials that can be molded while soft and then hardened into a rigid, semi-elastic, or elastic form, including a wide range of organic polymers such as polyolefins, polyesters, and polyamides. One example of a plastic is polypropylene (PP).

[0043] The term "about" means ±10% of the recited number. For example, "about 100" means 90 to 110, inclusive.

[0044] Various Non-Limiting Embodiments of the Invention It is an object of the present invention to provide a method and system for providing decomposition of PP waste that overcomes the limitations of known methods and systems.

[0045] The present invention provides a method for the degradation of PP, which produces low-molecular-weight oxidized monomers that can be used to synthesize higher-value materials. Such monomers include short-chain dicarboxylic acids, which are building blocks for materials including, but not limited to, polyamides and polyurethanes. In addition, the low-molecular-weight carboxylic acids and acid mixtures can be converted by bacteria into new products such as lipids, oils, pigments, and proteins.

[0046] In various embodiments, the present invention provides a method for decomposing PP waste, the method comprising: adding the PP waste to a first reaction vessel; adding at least one oxidizing agent to the first reaction vessel; and subjecting the PP waste in the first reaction vessel to conditions effective to decompose the PP waste and produce a decomposition mixture. In some embodiments, the method further comprises producing at least one first off-gas. In some embodiments, the method further comprises collecting and regenerating the oxidizing agent. In some embodiments, the method further comprises transferring the decomposition mixture to a first distillation unit. In some embodiments, the method further comprises removing at least a portion of the oxidizing agent from the decomposition mixture to form a decomposition slurry. In some embodiments, the decomposition slurry comprises at least one compound containing at least one carboxyl group and at least one residual oxidizing agent. In some embodiments, the at least one compound containing at least one carboxyl group is at least one organic acid. In some embodiments, the method further comprises transferring the decomposition slurry to a second reaction vessel. In some embodiments, the method further includes adding at least one alcohol to a second reaction vessel to form an esterification reaction mixture and subjecting the esterification reaction mixture to conditions effective to form an esterification product mixture. In some embodiments, the esterification product mixture includes at least one residual oxidant, at least one alcohol, and at least one ester. In some embodiments, the method further includes transferring the esterification product mixture to a second distillation unit. In some embodiments, the method further includes separating the esterification product mixture in the second distillation unit into a residual oxidant waste stream, an ester stream, and an alcohol stream. In some embodiments, the ester stream includes at least one organic acid in the form of at least one ester. In some embodiments, the method further includes adding at least one solid catalyst to the first reaction vessel. In some embodiments, the method optionally includes adding at least one solid catalyst to the first reaction vessel.In some embodiments, the method may include adding at least one solid catalyst to the first reaction vessel.

[0047] In various embodiments, the present invention provides methods for decomposing PP waste, the methods including adding the PP waste to a reaction vessel, adding at least one oxidizing agent to the reaction vessel, and subjecting the PP waste to conditions effective to decompose the PP waste to produce a decomposition mixture. In some embodiments, the methods further include adding at least one solid catalyst to the reaction vessel. In some embodiments, the methods include optionally adding at least one solid catalyst to the reaction vessel. In some embodiments, the methods may include adding at least one solid catalyst to the reaction vessel. In some embodiments, the conditions include a temperature range, an initial gas pressure range, and a residence time in the reaction vessel.

[0048] In various embodiments, the present invention provides a method for decomposing PP waste, the method comprising: adding the PP waste to a reaction vessel; adding at least one oxidizing agent to the reaction vessel; optionally adding at least one solid catalyst to the reaction vessel; and subjecting the PP waste to conditions effective to decompose the PP waste to produce a decomposition mixture. In some embodiments, the conditions include a temperature range, an initial gas pressure range, and a residence time in the reaction vessel.

[0049] In various embodiments, the present invention provides methods for decomposing PP waste, comprising adding the PP waste to a reaction vessel, adding at least one oxidizing agent to the reaction vessel, optionally adding at least one solid catalyst to the reaction vessel, and subjecting the PP waste to conditions effective to decompose the PP waste to produce a decomposition mixture, the conditions comprising a temperature range, an initial gas pressure range, and a residence time in the reaction vessel.

[0050] In some embodiments, the method is selected from the group consisting of a batch process, a continuous process, a substantially continuous process, and a semi-continuous process.

[0051] In some embodiments, the present invention provides a system for decomposing PP waste, comprising a first reaction vessel, a condenser, a pollution abatement unit, a concentration unit, a first distillation unit, a second reaction vessel, and a second distillation unit, wherein the first reaction vessel is connected to the condenser and the first distillation unit, the condenser is connected to the pollution abatement unit and the first reaction vessel, the pollution abatement unit is connected to the concentration unit, the concentration unit is connected to the pollution abatement unit, the first distillation unit is connected to the concentration unit and the second reaction vessel, the second reaction vessel is connected to the second distillation unit, and the second distillation unit is connected to the second reaction vessel.

[0052] reaction vessel Non-limiting examples of reaction vessels suitable for use in the processes and / or methods of the invention (e.g., reactors, glass-lined reactors, glass flasks, containers, etc., in which the processes and / or methods of the invention are carried out) are generally closed (not open to ambient air) and optionally pressurizable reactors; particularly non-limiting types of closed, pressurizable reactors suitable for batch, continuous, substantially continuous, or semi-continuous processes according to the invention include reactors and autoclaves from Parr Instrument Company, Amar Equipments, Buchiglas, and Berghof. In some embodiments, the reaction vessel is pressurized. In some embodiments, the reaction vessel is not pressurized.

[0053] In some embodiments, the reaction vessel is at least one selected from the group consisting of a reactor, a glass flask, a glass-lined reactor, and combinations thereof.

[0054] In some embodiments, related types of reaction vessels for carrying out batch, or continuous, substantially continuous, or semi-continuous processes include substantially vertically oriented reaction vessels into which the PP waste and any additional reagents / materials of interest (e.g., gases, liquids, solids) may be contained, and into which gas may be introduced continuously or at intervals, under pressure or at ambient pressure, via one or more inlets, ports, valves, etc., located at or near the bottom of the reaction vessel and / or at other locations along the length of the reaction vessel, and which may preferably but optionally have an upper headspace or free volume. Such reaction vessels may be essentially cylindrical, tubular, or any other suitable shape. In some embodiments, reaction vessels for carrying out batch, or continuous, substantially continuous, or semi-continuous processes include substantially horizontally oriented reactors.

[0055] In batch, continuous, substantially continuous, or semi-continuous processes, it is generally desirable to cause mixing, where possible, of the PP waste with any additional reagents / materials (e.g., gases, liquids, solids) and any solid, liquid, and gas phases that may be present in the reaction vessel. In some embodiments, the PP is added in the form of solid PP, molten PP, or shredded PP. In some embodiments, mixing may be suitably achieved by mechanical stirring, although agitation of the entire reaction vessel or other means of causing mixing may be applicable. In some embodiments, mixing may be suitably achieved by recirculation by means such as a pump, impeller wheel, or rotating scraper.

[0056] Heat may be supplied to the reaction mixture and / or reaction system (e.g., the PP waste and any additional reagents / materials (e.g., gas, liquid, solid), and any solid and liquid and gas phases that may be present in the reactor) by any suitable method. Non-limiting examples include immersion of the reaction vessel in a suitable heating bath (containing, for example, oil, molten salt or molten salt mixture, superheated steam, etc.), by means of thermally conductive (typically metal) tubing wrapped around the outside of the reaction vessel and / or immersed in the reaction medium itself, and through which hot oil, superheated steam, etc. are suitably passed, or similarly by means of one or more electrical resistance heating elements wrapped around the outside of the reaction vessel and / or immersed in the reaction medium, a heating mantle, or by means of a jacketed reactor as known in the art. Other applicable heating methods include induction heating (e.g., of a metal reactor housing) and microwave heating.

[0057] In some embodiments, the reaction is carried out in a batch process. In other embodiments, the reaction is carried out in a continuous process.

[0058] In a batch process, in some embodiments, an oxidizing agent (e.g., nitric acid) is added to the reactor before heating and stirring begin. Once the reactor reaches the desired temperature, PP is added, and the reaction is allowed to proceed with stirring for a desired period of time. In some embodiments, the PP is added in the form of solid PP, molten PP, or shredded PP. In some embodiments, the oxidizing agent (e.g., nitric acid) is refluxed within the reaction vessel using a condenser during the process. After the reaction is complete, the reactor is allowed to cool, and the reaction mixture (including the liquid stream and the solid stream) is filtered, for example, through filter paper, a sieve, or a Buchner funnel. The solid stream contains unreacted or incompletely reacted PP. The liquid stream contains dilute nitric acid, dissolved dicarboxylic acids, and other compounds, such as nitro-substituted dicarboxylic acids. In some embodiments, the liquid stream is then heated, and the oxidizing agent (e.g., nitric acid) and water are separated from the dicarboxylic acids by distillation.

[0059] In a continuous process, in some embodiments, a desired initial amount of oxidizing agent (e.g., nitric acid) is added to the reactor before heating and stirring begin. Once the reactor reaches the desired temperature, PP is added. In some embodiments, PP is added in the form of solid PP, molten PP, or shredded PP. The reactor outlet valve is then opened and the amount of product exiting the reactor is adjusted to a constant flow rate approximately equal to the amount of PP and oxidizing agent being added to the reactor, thereby maintaining approximately constant reactant and product volumes within the reactor throughout the process. In some embodiments, the oxidizing agent (e.g., nitric acid) is refluxed within the reactor using a condenser during the process. In some embodiments, samples are taken at timed intervals, cooled, and filtered, for example, using filter paper, a sieve, or a Buchner funnel. The liquid stream contains dilute nitric acid, dissolved dicarboxylic acids, and other compounds, such as nitro-substituted dicarboxylic acids. In some embodiments, the liquid stream is then heated, and the oxidizing agent (e.g., nitric acid) and water are separated from the dicarboxylic acids by distillation.

[0060] Temperature range In some embodiments, the temperature range is 60° C. to 225° C. In some embodiments, the temperature range in the reaction vessel is 60° C. to 200° C. In some embodiments, the reaction vessel is a first reaction vessel.

[0061] In some embodiments, the temperature range is 60°C to 200°C, 60°C to 175°C, 60°C to 150°C, 60°C to 125°C, 60°C to 100°C, 60°C to 90°C, 60°C to 80°C, or 60°C to 70°C.

[0062] In some embodiments, the temperature range is 60°C to 200°C, 70°C to 200°C, 80°C to 200°C, 90°C to 200°C, 100°C to 200°C, 100°C to 200°C, 120°C to 200°C, 130°C to 200°C, 140°C to 200°C, 150°C to 200°C, 160°C to 200°C, 170°C to 200°C, 180°C to 200°C, or 190°C to 200°C.

[0063] Initial pressure range of gas In some embodiments, the initial pressure of the gas is between 0 psi and 1000 psi. In some embodiments, the initial pressure of the gas in the reaction vessel is between 0 psi and 1000 psi. In some embodiments, the reaction vessel is a first reaction vessel.

[0064] In some embodiments, the initial pressure of the gas is between 0 psi and 900 psi, between 0 psi and 800 psi, between 0 psi and 700 psi, between 0 psi and 600 psi, between 0 psi and 500 psi, between 0 psi and 400 psi, between 0 psi and 300 psi, between 0 psi and 200 psi, or between 0 psi and 100 psi.

[0065] Residence time in the reactor In some embodiments, the residence time in the reaction vessel is one selected from the group consisting of 30 minutes to 30 hours, less than 30 minutes, and more than 30 hours. In some embodiments, the reaction vessel is a first reaction vessel.

[0066] In some embodiments, the residence time in the reaction vessel is 30 minutes to 30 hours, 30 minutes to 29 hours, 30 minutes to 28 hours, 30 minutes to 27 hours, 30 minutes to 26 hours, 30 minutes to 25 hours, 30 minutes to 24 hours, 30 minutes to 23 hours, 30 minutes to 22 hours, 30 minutes to 21 hours, 30 minutes to 20 hours, 30 minutes to 19 hours, 30 minutes to 18 hours, 30 minutes to 17 hours, 30 minutes to 16 hours, 30 minutes to 15 hours, 30 minutes to 14 hours, 30 minutes to 13 hours, 30 minutes to 12 hours, 30 minutes to 11 hours, 30 minutes to 10 hours, 30 minutes to 9 hours, 30 minutes to 8 hours, 30 minutes to 7 hours, 30 minutes to 6 hours, 30 minutes to 5 hours, 30 minutes to 4 hours, 30 minutes to 3 hours, 30 minutes to 2 hours, or 30 minutes to 1 hour.

[0067] In some embodiments, the residence time in the reaction vessel is 30 minutes, 25 minutes, 20 minutes, 15 minutes, 10 minutes, or 5 minutes.

[0068] In some embodiments, the residence time in the reaction vessel is 30 hours, 35 hours, 40 hours, 45 hours, 50 hours, 55 hours, 60 hours, 65 hours, 70 hours, or 75 hours. In some embodiments, the residence time in the reaction vessel is about 1 hour to about 10 hours. In some embodiments, the residence time in the reaction vessel is about 3 hours to about 6 hours.

[0069] Effects of time, temperature, pressure, and concentration Depending on the time, temperature, and pressure of the reaction, different products and amounts of products are obtained.

[0070] oxidizing agent In some embodiments, the at least one oxidizing agent is selected from the group consisting of oxygen (O), nitric oxide (NO), nitrous oxide (NO), nitrogen dioxide (NO), nitric acid (HNO), aqueous nitric acid (HNO), and combinations thereof.

[0071] In some embodiments, the aqueous nitric acid solution has a concentration of 10% to 100% by weight, 10% to 90% by weight, 10% to 80% by weight, 10% to 70% by weight, 10% to 60% by weight, 10% to 50% by weight, 10% to 40% by weight, 10% to 30% by weight, or 10% to 20% by weight.

[0072] In some embodiments, the aqueous nitric acid solution has a concentration of 10% to 100% by weight, 20% to 100% by weight, 30% to 100% by weight, 40% to 100% by weight, 50% to 100% by weight, 60% to 100% by weight, 70% to 100% by weight, 80% to 100% by weight, or 90% to 100% by weight. In some embodiments, the aqueous nitric acid solution has a concentration of about 67 to about 70% by weight.

[0073] solid catalyst In some embodiments, the at least one solid catalyst is selected from the group consisting of zeolites, aluminas, silicoaluminophosphates, sulfated zirconia, zinc oxide, titanium oxide, zirconium oxide, niobium oxide, iron carbonate, calcium carbide, and combinations thereof.

[0074] Contaminated PP waste In various embodiments, but not limited to, the PP waste may be contaminated with other plastic and / or non-plastic waste and may be obtained from at least one of the following sources: municipal solid waste or marine debris.

[0075] The term "municipal solid waste" refers to the waste type commonly known as trash, garbage, refuse, or rubbish, consisting of various items discarded by the public. The composition of municipal solid waste may include various waste types, may vary from municipality to municipality, and may change over time. In some embodiments, municipal solid waste may further include at least one other waste type, such as biodegradable waste, recyclable materials, inert waste, electrical and electronic waste, composite waste, contaminated plastic waste, and combinations thereof.

[0076] The term "marine debris" refers to human-created waste types that are intentionally or accidentally released into lakes, rivers, seas, oceans, canals, or waterways. In some cases, marine debris may be mixed with naturally occurring materials (e.g., driftwood, kelp, microorganisms, etc.). In some embodiments, the marine debris includes at least one type of contaminated plastic waste.

[0077] The term "contaminated PP waste" refers to PP and / or PP materials that have been discarded after use and / or production, where the PP and / or PP materials are mixed with or contaminated by at least one plastic and / or non-plastic material. In various embodiments, the contaminated PP waste comprises at least one PP material and at least one non-plastic material. In various embodiments, the contaminated PP waste consists of at least one PP material and at least one non-plastic material. In various embodiments, the contaminated PP waste consists essentially of at least one PP material and at least one non-plastic material.

[0078] Non-limiting examples of biodegradable waste include food and kitchen waste, green waste, paper, etc. Non-limiting examples of recyclable materials include paper, cardboard, glass, bottles, jars, tin cans, aluminum cans, aluminum foil, metal, certain plastics, fabric, cloth, tires, batteries, etc. Non-limiting examples of inert waste include construction and demolition waste, soil, rocks, debris, sand, concrete, etc. Non-limiting examples of e-waste include appliances, light bulbs, washing machines, TVs, computers, screens, mobile phones, alarm clocks, watches, etc. Non-limiting examples of mixed waste include discarded clothing, toys, etc.

[0079] plastic materials In various embodiments, the PP material comprises at least one selected from the group consisting of PP film, PP foam, PP packaging, PP bags, PP wrap, and combinations thereof. In some embodiments, the PP material is at least one selected from the group consisting of PP film, PP foam, PP packaging, PP bags, PP wrap, and combinations thereof.

[0080] Non-plastic materials In the broadest sense, a non-plastic material is any material that is not a plastic or plastic material. Non-limiting examples of non-plastic materials include non-plastic organic materials, inorganic materials, fluids (non-plastic fluids), etc. In various embodiments, the non-plastic material comprises at least one selected from the group consisting of non-plastic organic materials, inorganic materials, fluids, and combinations thereof.

[0081] Non-plastic organic materials In some embodiments, the non-plastic organic material is at least one selected from the group consisting of plant material, animal material, algal material, bacterial material, fungal material, viral material, biological material, cellulose material, cellulosic material, cellulose-containing material, and combinations thereof.

[0082] As used herein, the term "biological material" refers to material that originates from, is harvested, isolated, derived, and / or obtained from a biological organism.

[0083] In some embodiments, the non-plastic organic material is at least one selected from the group consisting of plant-derived materials, animal-derived materials, algae-derived materials, bacterial-derived materials, fungal-derived materials, virus-based materials, biologically-derived materials, and combinations thereof.

[0084] In some embodiments, the non-plastic organic material is at least one cellulosic material, hi some embodiments, the at least one cellulosic material is at least one selected from the group consisting of paper-based materials, paper, paperboard, wood, engineered wood, plant fibers, textiles, fabrics, and combinations thereof.

[0085] inorganic material In its broadest sense, the term "inorganic material" generally refers to a material that is not an organic compound or material. Non-limiting examples of inorganic materials include rocks, minerals, glass, ceramics, metals, etc.

[0086] fluid Non-limiting examples of fluids include water, hydrocarbons, synthetic fluids, naturally occurring fluids, acids, bases, or biological fluids, or any mixture or combination thereof.

[0087] In some embodiments, the fluid is at least one selected from the group consisting of water, hydrocarbons, synthetic fluids, naturally occurring fluids, acids, bases, biological fluids, and combinations thereof.

[0088] Non-limiting examples of water include saltwater, seawater, freshwater, reclaimed water, recycled water, or wastewater, or any mixture or combination thereof.

[0089] In some embodiments, the water is at least one selected from the group consisting of saltwater, seawater, freshwater, reclaimed water, recycled water, wastewater, and combinations thereof.

[0090] decomposition mixture In various embodiments, the degradation mixture comprises a solid phase and a liquid phase.

[0091] In various embodiments, the solid phase comprises at least one selected from the group consisting of an oligomer, a polymer, and combinations thereof.

[0092] In various embodiments, the solid phase further comprises at least one solid catalyst. In some embodiments, the solid phase optionally comprises at least one solid catalyst. In some embodiments, the solid phase may comprise at least one solid catalyst.

[0093] In various embodiments, the liquid phase comprises at least one compound comprising at least one carboxyl group. In various embodiments, the liquid phase comprises at least one compound containing at least one carboxyl group and, optionally, at least one nitro group.

[0094] In various embodiments, the at least one compound comprising at least one carboxyl group is at least one organic acid. In various embodiments, the at least one compound containing at least one carboxyl group is at least one organic acid.

[0095] In some embodiments, the at least one organic acid is at least one selected from the group consisting of optionally substituted organic acids, substituted organic acids, and unsubstituted organic acids.

[0096] In some embodiments, the at least one organic acid is at least one selected from the group consisting of monocarboxylic acids, dicarboxylic acids, polycarboxylic acids, and combinations thereof.

[0097] In some embodiments, the at least one monocarboxylic acid is at least one selected from the group consisting of optionally substituted monocarboxylic acids, substituted monocarboxylic acids, unsubstituted monocarboxylic acids, and combinations thereof.

[0098] In some embodiments, the at least one dicarboxylic acid is at least one selected from the group consisting of optionally substituted dicarboxylic acids, substituted dicarboxylic acids, unsubstituted dicarboxylic acids, and combinations thereof.

[0099] In some embodiments, the at least one polycarboxylic acid is at least one selected from the group consisting of optionally substituted polycarboxylic acids, substituted polycarboxylic acids, unsubstituted polycarboxylic acids, and combinations thereof.

[0100] In some embodiments, the at least one organic acid is at least one α,ω-dicarboxylic acid.

[0101] In some embodiments, the at least one α,ω-dicarboxylic acid is at least one selected from the group consisting of optionally substituted α,ω-dicarboxylic acids, substituted α,ω-dicarboxylic acids, unsubstituted α,ω-dicarboxylic acids, and combinations thereof. Optionally, the at least one α,ω-dicarboxylic acid is substituted with at least one nitro group. The nitro group may be substituted at the 2-position, 3-position, or internal position of the carboxylic acid chain. In addition, the at least one α,ω-dicarboxylic acid may be in the form of an anhydride.

[0102] In some embodiments, the α,ω-dicarboxylic acid is a C4-C 15 dicarboxylic acids. In other embodiments, the α,ω-dicarboxylic acid is a C4-C9 dicarboxylic acid. In other embodiments, if the dicarboxylic acid contains an even-numbered n carbon chain between the two carboxy groups, it is substituted with (n / 2)-1 methyl groups. In other embodiments, if the dicarboxylic acid contains an odd-numbered n carbon chain between the two carboxy groups, it is substituted with (n / 2)-1 or (n / 2)-2 methyl groups. All stereoisomers are possible. In other embodiments, the methyl-substituted α,ω-dicarboxylic acid is substituted with one or more nitro groups. In some embodiments, the methyl-substituted α,ω-dicarboxylic acid is substituted with one or more nitro groups at the 2-, 3-, 4-, or other internal positions of the α,ω-dicarboxylic acid.

[0103] In some embodiments, the at least one organic acid is at least one selected from succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecane diacid, dodecane diacid, and combinations thereof, and the at least one organic acid is optionally substituted with one or more methyl groups.

[0104] In some embodiments, the degradation mixture comprises a composition comprising at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, and combinations thereof, wherein the succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid are optionally substituted with one or more methyl groups.

[0105] In some embodiments, the liquid phase comprises a composition comprising at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, and combinations thereof, wherein the succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid are optionally substituted with one or more methyl groups.

[0106] In some embodiments, the liquid phase comprises a composition including at least one of 2-methylsuccinic acid, 3-methylglutaric acid, 2,4-dimethylglutaric acid, 2,4-dimethyladipic acid, 3,5-dimethylpimelic acid, 2,4,6-trimethylpimelic acid, 2,4,6-trimethylsebacic acid, 2,4,6,8-tetramethylazelaic acid.

[0107] In some embodiments, the liquid phase is selected from the group consisting of methylbutanedioic acid dimethyl ester, methylbutanedioic acid dimethyl ester, methylbutanedioic acid dimethyl ester, 2,4-dimethylpentanedioic acid dimethyl ester, 2-formyl-1,4-benzenedicarbonitrile, cis-hexahydro-1H-cyclopenta[c]thiophene, 2,4-dimethylpentanedioic acid dimethyl ester, cis-hexahydro-1H-cyclopenta[c]thiophene, 2-methyl-5-(methylthio)furan, 5-acetoxy-3-methylhexanoic acid methyl ester, (R,R)-(−)-2,4-dimethyl-9-decenoic acid methyl ester, 2-methylheptanedioic acid dimethyl ester, 3,5-dimethylheptanedioic acid dimethyl ester, 2-butylquinoline, cyclohexanecarboxylic acid ethyl ester, 3-cyclobut-1-enyl-hydroxy-2-methylpropionic acid methyl ester, adipic acid methyl propyl ester, 2-methyl-3-cyclopropylpropanoic acid methyl ester, 1-Cyclopentyl-3-ethoxy-2-propanone, cis-1,2-diethylcyclohexane, 1,2-diethyl-3-methylcyclohexane, 2,2,7,7-tetramethyloctanedioic acid, (2S,4R)-(+)-2,4-dimethyl-9-decenoic acid methyl ester, O-fluoroacetophenone oxime, meta-methoxybenzenethiol, trans-2-(1-mercapto-1-methylethyl)-5-methylcyclohexanone, 4-methoxybenzenethiol, The present invention includes compositions comprising at least one of dibenzo[b,f]oxepin-3-ylamine, (4-ethoxyphenyl)carbamic acid ethyl ester, 2-(1-methyl-1H-imidazol-4-yl)quinoline, 2,8-bis(1,5,5-trimethylpyrrolidine-2,4-dione-3-ylidene)-3,7-diazanonane, 2-amino-3,5,7,8-tetrahydro-4,6-pteridinedione, and 1,2-dimethoxy-4-(1,2-dimethoxyethyl)benzene.

[0108] In some embodiments, the method further comprises separating the at least one organic acid.

[0109] Non-limiting examples of separation techniques include simple distillation, fractional distillation, azeotropic distillation, co-distillation, fractional crystallization, standard crystallization, freeze-drying, supercritical fluid extraction, solvent extraction, precipitation, and combinations thereof. In some embodiments, the separation is carried out by at least one selected from the group consisting of simple distillation, fractional distillation, azeotropic distillation, co-distillation, fractional crystallization, standard crystallization, freeze-drying, supercritical fluid extraction, solvent extraction, precipitation, and combinations thereof.

[0110] Esterification The conversion of at least one compound (e.g., organic acid) containing at least one carboxyl group from its acid form to an ester occurs by a process commonly known in the art as esterification. In some embodiments, the conversion of at least one compound containing at least one carboxyl group from its acid form to an ester form occurs under esterification conditions. In some embodiments, the dicarboxylic acid is at least partially in the form of an ester.

[0111] In some embodiments, the method further comprises converting the at least one organic acid to at least one corresponding ester. In some embodiments, the at least one corresponding ester is at least one selected from the group consisting of methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, sec-butyl ester, tert-butyl ester, pentyl ester, and hexyl ester, and combinations thereof. In some embodiments, the at least one corresponding ester is a methyl ester. In some embodiments, the conversion is carried out by esterification or esterifying.

[0112] In some embodiments, the method further comprises combining at least one organic acid with at least one alcohol to form an esterification mixture and subjecting the esterification mixture to conditions effective to form at least one ester. Any suitable esterification conditions known in the art may be used to form at least one ester. For example, at least one organic acid may be mixed with at least one alcohol, and the mixture may be heated to cause esterification. A mineral acid may be added as a catalyst.

[0113] In some embodiments, the at least one alcohol is at least one selected from the group consisting of straight chain alcohols, branched alcohols, cyclic alcohols, and combinations thereof. In some embodiments, the at least one alcohol is at least one selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, tert-butanol, pentanol, hexanol, and combinations thereof. In some embodiments, the at least one alcohol is at least one selected from the group consisting of C1-C 10 In some embodiments, the at least one alcohol is a C1-C4 alcohol. In some embodiments, the at least one alcohol is methanol.

[0114] In some embodiments, at least one organic acid is independently in at least one ester form. In some embodiments, at least one ester or ester form is at least one selected from the group consisting of methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, sec-butyl ester, tert-butyl ester, pentyl ester, and hexyl ester, and combinations thereof. In some embodiments, at least one ester form or ester is methyl ester.

[0115] In some embodiments, at least one organic acid is in ester form. In some embodiments, the α,ω-dicarboxylic acid is in ester form. In some embodiments, succinic acid is in ester form. In some embodiments, glutaric acid is in ester form. In some embodiments, adipic acid is in ester form. In some embodiments, pimelic acid is in ester form. In some embodiments, suberic acid is in ester form. In some embodiments, azelaic acid is in ester form. In some embodiments, sebacic acid is in ester form. In some embodiments, undecanedioic acid is in ester form. In some embodiments, dodecanedioic acid is in ester form.

[0116] In some embodiments, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and azelaic acid are each independently in an ester form.

[0117] In some embodiments, oxalic acid, suberic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, 2-octenedioic acid, 2-nonenedioic acid, 2-decenedioic acid, and 2-undecenedioic acid are independently in ester form.

[0118] In some embodiments, nitro-suberic acid, nitro-azelaic acid, nitro-sebacic acid, nitro-undecanedioic acid, nitro-dodecanedioic acid, nitro-brassylic acid, nitro-tetradecanedioic acid, nitro-pentadecanedioic acid, nitro-hexadecanedioic acid, nitro-heptadecanedioic acid, nitro-octadecanedioic acid, nitro-nonadecanedioic acid, and nitro-icosane dioic acid are independently in ester form.

[0119] In some embodiments, C-C substituted with a single nitro group 20 The dicarboxylic acid is in the form of an ester. In some embodiments, a C8-C substituted with a single nitro group is in the form of an ester. 20The dicarboxylic acid is nitro-suberic acid, nitro-azelaic acid, nitro-sebacic acid, nitro-undecanedioic acid, nitro-dodecanedioic acid, nitro-brassylic acid, nitro-tetradecanedioic acid, nitro-pentadecanedioic acid, nitro-hexadecanedioic acid, nitro-heptadecanedioic acid, nitro-octadecanedioic acid, nitro-nonadecanedioic acid, or nitro-icosane dioic acid. In some embodiments, 20 The dicarboxylic acid is substituted at the 2-, 3-, or other internal position. In some embodiments, 20 The dicarboxylic acid is 2-nitro-suberic acid, 2-nitro-azelaic acid, 2-nitro-sebacic acid, 2-nitro-undecanedioic acid, 2-nitro-dodecanedioic acid, 2-nitro-brassylic acid, 2-nitro-tetradecanedioic acid, 2-nitro-pentadecanedioic acid, 2-nitro-hexadecanedioic acid, 2-nitro-heptadecanedioic acid, 2-nitro-octadecanedioic acid, 2-nitro-nonadecanedioic acid, or 2-nitro-icosane dioic acid, or a salt or ester thereof. In some embodiments, the dicarboxylic acid is C8-C 20 The dicarboxylic acid is 3-nitro-suberic acid, 3-nitro-azelaic acid, 3-nitro-sebacic acid, 3-nitro-undecanedioic acid, 3-nitro-dodecanedioic acid, 3-nitro-brassylic acid, 3-nitro-tetradecanedioic acid, 3-nitro-pentadecanedioic acid, 3-nitro-hexadecanedioic acid, 3-nitro-heptadecanedioic acid, 3-nitro-octadecanedioic acid, 3-nitro-nonadecanedioic acid, or 3-nitro-icosane dioic acid, or a salt or ester thereof. In some embodiments, the ester form is selected from the group consisting of monoesters, diesters, polyesters, mixed diesters, mixed polyesters, and combinations thereof.

[0120] As used herein, the term "multiester" means an ester formed by converting two or more carboxyl groups from the acid form to the ester form under esterifying conditions.

[0121] In some embodiments, the ester forms include α,ω-diesters, optionally substituted α,ω-dicarboxylic acids, or substituted α,ω-dicarboxylic acids, unsubstituted α,ω-dicarboxylic acids, and combinations thereof.

[0122] In some embodiments, the at least one ester is selected from the group consisting of dimethyl succinate, dimethyl glutarate, dimethyl adipate, dimethyl pimelate, dimethyl suberate, dimethyl azelaate, dimethyl sebacate, dimethyl undecanedioate, dimethyl dodecanedioate, dimethyl oxalate, dimethyl tridecanedioate, dimethyl tetradecanedioate, dimethyl pentadecanedioate, dimethyl 2-octenedioate, dimethyl 2-nonenedioate, 2-dimethyl 2-decenedioate, dimethyl 2-undecenedioate, dimethyl 2-nitro-suber ... ethyl, 2-nitro-dimethylazelate, 2-nitro-dimethylsebacate, 2-nitro-dimethylundecanedioate, 2-nitro-dimethyldodecanedioate, 2-nitro-dimethylbrassylate, 2-nitro-dimethylheptadecanedioate, 2-nitro-dimethyloctadecanedioate, 2-nitro-dimethyltetradecanedioate, 2-nitro-dimethylpentadecanedioate, 2-nitro-dimethylhexadecanedioate, 2-nitro-heptadecanedioate, 2-nitro-dimethylsuberate, 2-nitro-dimethylsebacate, 2 Dimethyl 2-nitro-undecanedioate, dimethyl 2-nitro-dodecanedioate, dimethyl 2-nitro-tetradecanedioate, and dimethyl 2-nitro-pentadecanedioate, dimethyl 3-octenedioate, dimethyl 3-nonenedioate, dimethyl 3-decenedioate, dimethyl 3-undecenedioate, dimethyl 3-nitro-suberate, dimethyl 3-nitro-azelate, dimethyl 3-nitro-sebacate, dimethyl 3-nitro-undecanedioate, dimethyl 3-nitro-dodecanedioate, dimethyl 3-nitro-brassylate, dimethyl 3-nitro dimethyl 3-nitro-heptadecanedioate, dimethyl 3-nitro-octadecanedioate, dimethyl 3-nitro-tetradecanedioate, dimethyl 3-nitro-pentadecanedioate, dimethyl 3-nitro-hexadecanedioate, 3-nitro-heptadecanedioate, dimethyl 3-nitro-suberate, dimethyl 3-nitro-sebacate, dimethyl 3-nitro-undecanedioate, dimethyl 3-nitro-dodecanedioate, dimethyl 3-nitro-tetradecanedioate, and dimethyl 3-nitro-pentadecanedioate, and combinations thereof.

[0123] In some embodiments, the at least one corresponding ester comprises dimethyl succinate, dimethyl glutarate, dimethyl adipate, dimethyl pimelate, dimethyl suberate, dimethyl azelaate, dimethyl sebacate, dimethyl undecanedioate, dimethyl dodecanedioate, and combinations thereof.

[0124] In some embodiments, the esterification mixture comprises a composition comprising at least one of dimethyl succinate, dimethyl glutarate, dimethyl adipate, dimethyl pimelate, dimethyl suberate, dimethyl azelaate, dimethyl sebacate, dimethyl undecanedioate, dimethyl dodecanedioate, and combinations thereof.

[0125] In some embodiments, the at least one corresponding ester comprises 2-methylsuccinic acid dimethyl ester, 3-methylglutaric acid dimethyl ester, 2,4-dimethylglutaric acid dimethyl ester, 2,4-dimethyladipic acid dimethyl ester, 3,5-diethylpimelic acid dimethyl ester, 2,4,6-trimethylpimelic acid dimethyl ester, 4,6-trimethylsebacic acid dimethyl ester, 2,4,6,8-tetramethylazelaic acid, or a combination thereof.

[0126] In some embodiments, the esterification mixture comprises a composition comprising at least one of 2-methylsuccinic acid dimethyl ester, 3-methylglutaric acid dimethyl ester, 2,4-dimethylglutaric acid dimethyl ester, 2,4-dimethyladipic acid dimethyl ester, 3,5-diethylpimelic acid dimethyl ester, 2,4,6-trimethylpimelic acid dimethyl ester, 4,6-trimethylsebacic acid dimethyl ester, 2,4,6,8-tetramethylazelaic acid, or a combination thereof.

[0127] In some embodiments, the method further comprises separating at least one corresponding ester. In some embodiments, the separation is performed by distillation. In some embodiments, the separation of the at least one corresponding ester is performed by distillation. In some embodiments, the distillation is at least one selected from the group consisting of simple distillation, fractional distillation, vacuum distillation, azeotropic distillation, co-distillation, and combinations thereof.

[0128] In some embodiments, the method further comprises converting at least one compound containing at least one carboxyl group from an ester form to an acid form (e.g., converting the ester form back to the acid form). In some embodiments, the conversion from the ester form to the acid form is carried out under ester hydrolysis conditions.

[0129] salt In some embodiments, the method further comprises converting the at least one dicarboxylic acid to at least one corresponding salt. In some embodiments, the at least one corresponding salt is prepared by reacting the at least one dicarboxylic acid with a base to form an ionic salt of the at least one dicarboxylic acid. Bases include, but are not limited to, alkali metal salts, alkaline earth metal salts, and other metal ions. Exemplary ions include aluminum, calcium, lithium, magnesium, potassium, sodium, and zinc in their normal valences. Organic ions include protonated tertiary amine and quaternary ammonium cations, some of which include trimethylamine, diethylamine, N,N'-dibenzylethylenediamine, chloroprocaine, choline, diethanolamine, ethylenediamine, meglumine (N-methylglucamine), and procaine.

[0130] In some embodiments, the dicarboxylic acid is converted to an alkali metal salt. In some embodiments, the dicarboxylic acid is at least partially in the form of an alkali metal salt. The alkali metal salt can be made by reacting the dicarboxylic acid with an alkali metal hydroxide. Exemplary alkali metal hydroxides include sodium hydroxide, potassium hydroxide, and lithium hydroxide. Exemplary alkali metal salts of dicarboxylic acids include sodium salts, potassium salts, and lithium salts.

[0131] In some embodiments, oxalic acid, suberic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, 2-octenedioic acid, 2-nonenedioic acid, 2-decenedioic acid, and 2-undecenedioic acid are independently in the form of an alkali metal salt.

[0132] In some embodiments, 2-methylsuccinic acid, 3-methylglutaric acid, 2,4-dimethylglutaric acid, 2,4-dimethyladipic acid, 3,5-dimethylpimelic acid, 2,4,6-trimethylpimelic acid, 2,4,6-trimethylsebacic acid, 2,4,6,8-tetramethylazelaic acid are in the form of alkali metal salts.

[0133] In some embodiments, 2-nitro-suberic acid, 2-nitro-azelaic acid, 2-nitro-sebacic acid, 2-nitro-undecanedioic acid, 2-nitro-dodecanedioic acid, 2-nitro-brassylic acid, 2-nitro-tetradecanedioic acid, 2-nitro-pentadecanedioic acid, 2-nitro-hexadecanedioic acid, 2-nitro-heptadecanedioic acid, 2-nitro-octadecanedioic acid, 2-nitro-nonadecanedioic acid, and 2-nitro-icosane dioic acid are in the form of an alkali metal salt. In some embodiments, 3-nitro-suberic acid, 3-nitro-azelaic acid, 3-nitro-sebacic acid, 3-nitro-undecanedioic acid, 3-nitro-dodecanedioic acid, 3-nitro-brassylic acid, 3-nitro-tetradecanedioic acid, 3-nitro-pentadecanedioic acid, 3-nitro-hexadecanedioic acid, 3-nitro-heptadecanedioic acid, 3-nitro-octadecanedioic acid, 3-nitro-nonadecanedioic acid, and 3-nitro-icosane dioic acid are in the form of alkali metal salts.

[0134] In some embodiments, C-C substituted with a single nitro group 20 The dicarboxylic acid is in the form of an alkali metal salt. In some embodiments, a C8-C substituted with a single nitro group is 20 The dicarboxylic acids are nitro-suberic acid, nitro-azelaic acid, nitro-sebacic acid, nitro-undecanedioic acid, nitro-dodecanedioic acid, nitro-brassylic acid, nitro-tetradecanedioic acid, nitro-pentadecanedioic acid, nitro-hexadecanedioic acid, nitro-heptadecanedioic acid, nitro-octadecanedioic acid, nitro-nonadecanedioic acid, and nitro-icosane dioic acid in the form of their alkali metal salts. In some embodiments, C8-C 20The dicarboxylic acid may be 2-nitro-suberic acid, 2-nitro-azelaic acid, 2-nitro-sebacic acid, 2-nitro-undecanedioic acid, 2-nitro-dodecanedioic acid, 2-nitro-brassylic acid, 2-nitro-tetradecanedioic acid, 2-nitro-pentadecanedioic acid, 2-nitro-hexadecanedioic acid, 2-nitro-heptadecanedioic acid, 2-nitro-octadecanedioic acid, 2-nitro-nonadecanedioic acid, or 2-nitro-icosane diacid, 3-nitro- suberic acid, 3-nitro-azelaic acid, 3-nitro-sebacic acid, 3-nitro-undecanedioic acid, 3-nitro-dodecanedioic acid, 3-nitro-brassylic acid, 3-nitro-tetradecanedioic acid, 3-nitro-pentadecanedioic acid, 3-nitro-hexadecanedioic acid, 3-nitro-heptadecanedioic acid, 3-nitro-octadecanedioic acid, 3-nitro-nonadecanedioic acid, or 3-nitro-icosane dioic acid, or a salt or ester thereof.

[0135] Some embodiments of the present invention may be defined as any of the following numbered paragraphs: 1. 1. A method for decomposing PP waste, comprising: adding the PP waste to a reaction vessel; adding at least one oxidizing agent to the reaction vessel; and subjecting the PP waste to conditions effective to decompose the PP waste to produce a decomposition mixture.

[0136] 2. 10. The process of paragraph 1, further comprising adding at least one solid catalyst to the reaction vessel.

[0137] 3. 10. The method of paragraph 1, wherein the conditions include a temperature range, an initial pressure range of the gas, and a residence time within the reaction vessel.

[0138] 4. 10. The method of paragraph 1, wherein the PP waste comprises at least one plastic material and at least one non-plastic material.

[0139] 5. 5. The method of paragraph 4, wherein the plastic material comprises at least one selected from the group consisting of plastic film, plastic foam, plastic packaging, plastic bags, plastic wrap, and combinations thereof.

[0140] 6. 5. The method of paragraph 4, wherein the non-plastic material comprises at least one selected from the group consisting of a non-plastic organic material, an inorganic material, a fluid, and combinations thereof.

[0141] 7. 10. The method of paragraph 1, further comprising separating the decomposition mixture into a solid phase and a liquid phase.

[0142] 8. 8. The method of paragraph 7, wherein the solid phase comprises at least one selected from the group consisting of an oligomer, a polymer, and combinations thereof.

[0143] 9. 9. The method of paragraph 8, wherein the solid phase further comprises at least one solid catalyst.

[0144] 10. 8. The method of paragraph 7, wherein the liquid phase comprises at least one compound containing at least one carboxyl group.

[0145] 11. 11. The method of paragraph 10, wherein the at least one compound containing at least one carboxyl group is at least one organic acid.

[0146] 12. 12. The process of paragraph 11, further comprising converting the at least one organic acid to at least one corresponding ester.

[0147] 13. 12. The method of paragraph 11, wherein the at least one organic acid is selected from the group consisting of monocarboxylic acids, dicarboxylic acids, polycarboxylic acids, and combinations thereof.

[0148] 14. 12. The method of paragraph 11, wherein the at least one organic acid is an α,ω-dicarboxylic acid.

[0149] 15. 12. The method of paragraph 11, wherein the at least one organic acid is selected from the group consisting of 2-methylsuccinic acid, 3-methylglutaric acid, 2,4-dimethylglutaric acid, 2,4-dimethyladipic acid, 3,5-dimethylpimelic acid, 2,4,6-trimethylpimelic acid, 2,4,6-trimethylsebacic acid, 2,4,6,8-tetramethylazelaic acid, and combinations thereof.

[0150] 16. 12. The method of paragraph 11, further comprising separating the at least one organic acid.

[0151] 17. 13. The process of paragraph 12, further comprising isolating at least one corresponding ester.

[0152] 18. 3. The method of paragraph 2, wherein the at least one solid catalyst is selected from the group consisting of zeolites, aluminas, silicoaluminophosphates, sulfated zirconia, zinc oxide, titanium oxide, zirconium oxide, niobium oxide, iron carbonate, calcium carbide, and combinations thereof.

[0153] 19. 10. The method of paragraph 1, wherein the at least one oxidizing agent is selected from the group consisting of oxygen (O), nitric oxide (NO), nitrous oxide (NO), nitrogen dioxide (NO), nitric acid (HNO), aqueous nitric acid (HNO), and combinations thereof.

[0154] 20. 4. The method of paragraph 3, wherein the temperature range is 60°C to 200°C.

[0155] twenty one. 4. The method of paragraph 3, wherein the gas is at least one selected from the group consisting of air, nitrogen (N2), oxygen (O2), and combinations thereof.

[0156] twenty two. 4. The method of paragraph 3, wherein the initial pressure of the gas is between 0 psi and 1000 psi.

[0157] twenty three. 4. The method of paragraph 3, wherein the residence time in the reaction vessel is one selected from the group consisting of 30 minutes to 30 hours, less than 30 minutes, and more than 30 hours.

[0158] twenty four. 11. The process of paragraph 10, further comprising returning the oligomer, polymer, and combinations thereof to the reactor.

[0159] twenty five. 10. The process of paragraph 9, wherein the liquid phase further comprises at least one oxidizing agent.

[0160] 26. 26. The method of paragraph 25, further comprising collecting and regenerating the at least one oxidant.

[0161] 27. 12. The method of paragraph 11, wherein the at least one solid catalyst is selected from the group consisting of zeolites, aluminas, silicoaluminophosphates, sulfated zirconia, zinc oxide, titanium oxide, zirconium oxide, niobium oxide, iron carbonate, calcium carbide, and combinations thereof.

[0162] 38. 15. The method of paragraph 14, wherein the at least one corresponding ester is selected from the group consisting of 2-methylsuccinic acid dimethyl ester, 3-methylglutaric acid dimethyl ester, 2,4-dimethylglutaric acid dimethyl ester, 2,4-dimethyladipic acid dimethyl ester, 3,5-dimethylpimelic acid dimethyl ester, 2,4,6-trimethylpimelic acid dimethyl ester, 2,4,6-trimethylsebacic acid dimethyl ester, 2,4,6,8-tetramethylazelaic acid dimethyl ester, and combinations thereof.

[0163] This disclosure defines a complete chemical recycling system for PP that does not currently exist commercially. The chemical recycling process disclosed herein is unique and addresses the enormous plastic waste problem by diverting PP from landfills. The process converts PP into products that can be used in value-adding industrial applications (e.g., functional materials, polymers, fibers, compostable plastics, paints and coatings, lubricants, adhesives, fragrances, skin care products, etc.) that serve as drop-in replacements for existing chemical intermediates or as new chemical intermediates.

[0164] In this disclosure, PP is a polymer with many repeating carbon units that are successively broken down into shorter segments and functionalized (e.g., carbon chains can be oxidized to form dicarboxylic or monocarboxylic acids). The scission events continue until the chain length reaches a terminal length range and cannot be further broken (e.g., C2-C9 dicarboxylic acids), at which point an oxidizing agent depolymerizes the long-chain polymer into progressively shorter-chain species. Alternatively, the reaction process can be controlled to terminate the scission events early to achieve chain lengths longer than the terminal length range. These various chain lengths are collectively considered products. To enable the reaction of PP into products, an appropriate amount of oxidizing agent is added to break the polymer to the desired chain length. The oxidizing agent should be at an appropriate concentration and PP-to-oxidizing agent ratio to generate a large enough quantity of product for commercial use. The process and equipment described in this disclosure enable process control to convert PP into products containing terminal reactive species and / or other species of the desired chain length.

[0165] Both the overall process and individual units are optimized to economically convert PP into products and minimize the use of oxidizers and catalysts. Equipment for chemical recycling of PP is designed to optimize process performance metrics within its units (e.g., reactors are designed to maximize PP conversion, separation units are designed to recover and recycle oxidizers back to the reactor, and absorption units are designed to recover reaction gases and regenerate oxidizers). These units are combined into a process system designed to minimize energy use and recover and reuse oxidizers and catalysts to minimize process make-up. The process is also designed to minimize waste in the gas and liquid phases. Overall, this process can significantly improve the economics of producing products while diverting PP from waste streams (e.g., landfills and oceans) and extend carbon life. In addition, using PP for products reduces the use of petrochemical feedstocks traditionally used to make products.

[0166] Method for converting PP into reaction products Disclosed herein is a method / process for converting PP into reaction products or "products" using an oxidant and specific operating conditions (e.g., temperatures between 60°C and 200°C). This is a controlled chemical reaction within a reactor. The problem is that the oxidant is partially converted into reaction gases that exit the reactor as a gas phase. To make the process economical, this reaction gas is converted back to oxidant and recycled to the reactor. The product and oxidant remaining in the liquid phase are removed from the reactor and the product is separated. This disclosure details solutions for separating, recovering, and recycling the oxidant and recovering the product.

[0167] It is to be understood that this invention is not limited to the particular methodology, protocols, and reagents, etc., described herein and as such may vary. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention, which is defined solely by the claims.

[0168] Example The present invention is further described by the following examples, which are intended to be purely exemplary of the present invention and should not be construed as limiting the present invention in any way. The following examples are illustrative only and are not intended to limit any of the embodiments described herein in any way. The following examples are provided to better explain the claimed invention and should not be construed as limiting the scope of the present invention. To the extent that specific materials are mentioned, they are for illustrative purposes only and are not intended to limit the present invention. Those skilled in the art may develop equivalent means or reactants without the exercise of inventive capacity and without departing from the scope of the present invention.

[0169] Example 1 The raw material for this example was PP. This raw material was food storage containers of different shapes, including lunch boxes, margarine containers, yogurt pots, syrup bottles, medicine bottles, and several plastic bottle caps, all made from PP. These were contaminated with soil or some degree of organic matter and shredded into 0.5" to 1.5" squares or strips.

[0170] Typically, 5 grams (1-7 grams) of PP strips were added to a glass round-bottom flask. 100 grams of concentrated nitric acid (20%-70% nitric acid diluted with 30-80% water) was added to the round-bottom flask. While continuously stirring the contents of the round-bottom flask, the contents were heated to the desired temperature of 120°C (reflux) using a heating mantle. Once reflux began / the desired temperature was reached, the reaction was continued for 6 hours (1-24 hours). After the reaction was complete, the round-bottom flask was cooled to room temperature. The reaction generates a significant amount of gas, which escapes during the reaction. The reaction conditions are summarized in Table 1.

[0171] The final mixture consisted of a solid (unreacted / partially reacted PP), a liquid solution (a mixture of nitric acid and water), and the product dissolved in the liquid solution. The liquid solution was either pipetted away to separate it from the solid, or the solid was separated using glass fiber filter paper. The liquid solution was then decanted into a glass beaker, and the nitric acid / water mixture was allowed to evaporate overnight at 60°C. The product remaining in the glass beaker was analyzed for its chemical composition using various analytical instruments.

[0172] Example 2 The raw material for this example was PP. The raw material was PP food storage containers of different shapes, including lunch boxes, margarine containers, yogurt pots, syrup bottles, medicine bottles, and some plastic bottle caps. These were contaminated with soil or some organic matter and shredded into 0.5" to 1.5" squares or strips.

[0173] Typically, 5 grams (1-7 grams) of PP strip was placed in a glass liner. 100 grams of concentrated nitric acid (20%-70% nitric acid diluted with 30-80% water) was added to the liner and placed in the reaction vessel. The reactor was sealed, purged with inert gas (nitrogen / argon / helium), and pressurized with air from 0 psi to 600 psi. The reactor was then heated to the desired temperature of 120°C (120-150°C) while continuously stirring the contents. Once the internal temperature of the reaction vessel reached the target temperature, the reaction was continued for 120 minutes (2 hours). After 2 hours (reaction completion), the reactor was cooled to room temperature while continuing to stir. The reaction generated a significant amount of gas, which exited the reactor under pressure (10-100 psi), even after cooling. The reaction conditions are summarized in Table 1.

[0174] Once the reactor had cooled, it was vented and purged with an inert gas to remove trapped gas. The final mixture consisted of a solid (unreacted / partially reacted PP), a liquid solution (a mixture of nitric acid and water), and the product dissolved in the liquid solution. The liquid solution was either pipetted away to separate it from the solid, or the solid was separated using glass fiber filter paper. The liquid solution was then decanted into a glass beaker, and the nitric acid / water mixture was allowed to evaporate overnight at 60°C. The product remaining in the glass beaker was analyzed for its chemical composition using various analytical instruments.

[0175] [Table 1]

[0176] Table 2 shows the reaction products as determined by LCMS.

[0177] [Table 2]

[0178] Table 3 shows a summary of typical GCMS results from Example 2 (including peaks showing >1% of the total peak area).

[0179] [Table 3] TIFF0007738333000004.tif94162

[0180] The various methods and techniques described above provide numerous ways to implement the present application. Of course, it should be understood that a particular embodiment described herein may not necessarily achieve all of the objects and advantages described herein. Thus, for example, one skilled in the art will recognize that a method may be performed in a manner that achieves one advantage or a group of advantages as taught herein but without necessarily achieving other objects or advantages taught or suggested herein. Various alternatives are mentioned herein. It should be understood that some embodiments specifically include one, another, or more features, while other embodiments specifically exclude one, another, or more features, and yet other embodiments include one, another, or more advantageous features while attenuating a particular feature.

[0181] Furthermore, those skilled in the art will recognize the applicability of various features from different embodiments. Similarly, the various elements, features, and steps described above, and other known equivalents to such elements, features, or steps, may be used in various combinations by those skilled in the art to perform methods based on the principles described herein. In various embodiments, some of the various elements, features, and steps will be specifically included, and others will be specifically excluded.

[0182] Although the present application has been disclosed in the context of particular embodiments and examples, those skilled in the art will appreciate that the embodiments of the present application extend beyond the specifically disclosed embodiments to other alternative embodiments and / or uses and modifications thereof, and equivalents thereof.

[0183] Various embodiments of the present application are described herein, including the best mode known to the inventors for carrying out the application. Variations on these embodiments will become apparent to those skilled in the art upon reading the foregoing description. It is contemplated that those skilled in the art can employ such variations as appropriate, and that the application may be practiced in ways other than as specifically described herein. Accordingly, many embodiments of the present application include all modifications and equivalents of the subject matter recited in the claims appended hereto to the extent permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by this application unless otherwise stated herein or otherwise clearly contradicted by context.

[0184] All patents, patent applications, published patent applications, and other materials, such as articles, books, specifications, publications, documents, and / or articles, referenced herein are incorporated herein by this reference in their entirety for all purposes, except for any prosecution history documents related thereto that may contradict or conflict with this document or that may have a limiting effect on the broadest scope of any patent claim now or hereafter related to this document. By way of example, to the extent that a contradiction or conflict exists between the explanation, definition, and / or use of a term associated with any of the incorporated materials and that associated with this document, the explanation, definition, and / or use of the term in this document shall control.

[0185] It should be understood that the embodiments of the present application disclosed herein are illustrative of the principles of the embodiments of the present application. Other modifications that may be employed may fall within the scope of the present application. Thus, by way of example, but not of limitation, alternative configurations of the embodiments of the present application may be utilized based on the teachings herein. Accordingly, the embodiments of the present application are not limited to those precisely as shown and described.

[0186] Various embodiments of the present invention have been described in the above detailed description. While these descriptions directly describe the above embodiments, it is understood that those skilled in the art may envision modifications and / or variations to the specific embodiments shown and described herein. Any such modifications or variations that fall within the scope of this description are also intended to be included herein. Unless specifically noted, it is the inventors' intention that the words and phrases in the specification and claims be given their ordinary and accustomed meanings to one or more skilled artisans.

[0187] The foregoing description of various embodiments of the present invention known to applicant as of the time of filing this application is presented and is intended for purposes of illustration and description. This description is not intended to be exhaustive or to limit the invention to the precise form disclosed, as many modifications and variations are possible in light of the above teachings. The described embodiments serve to illustrate the principles of the present invention and its practical application, and to enable others skilled in the art to utilize the present invention in various embodiments and with various modifications as may be suitable for the particular use contemplated. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed for carrying out the invention.

[0188] While particular embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that, based on the teachings herein, changes and modifications may be made without departing from this invention and its broader aspects, and therefore, the appended claims are intended to encompass within their scope all such changes and modifications as are within the true spirit and scope of this invention.

Claims

1. 1. A method for decomposing polypropylene (PP) waste, comprising: a. adding PP waste to a reaction vessel; b. adding at least one oxidizing agent to the reaction vessel to provide a mixture, wherein the at least one oxidizing agent is an aqueous solution of nitric acid (HNO3); c. subjecting the mixture obtained in b. to conditions effective to decompose the PP waste to produce decomposition products, wherein the decomposition products comprise at least one dicarboxylic acid optionally substituted with a nitro group, and wherein the dicarboxylic acid or the dicarboxylic acid substituted with at least one nitro group is substituted with one or more methyl groups, or is a salt, ester, or anhydride thereof; A method comprising:

2. 10. The method of claim 1, wherein the decomposition products further comprise at least one carboxylic acid optionally substituted with a nitro group.

3. 3. The method according to claim 1, wherein the nitric acid has a concentration of 10 to 100 wt %.

4. 4. The method of claim 3, wherein the nitric acid has a concentration of about 67 to about 70 wt %.

5. 5. The method of any one of claims 1 to 4, wherein the weight ratio of nitric acid to PP is at least 3:

1.

6. 6. The method according to any one of claims 1 to 5, wherein the weight ratio of nitric acid to PP is 10-100:

1.

7. The method of any one of claims 1 to 6, wherein the conditions include a temperature range of 60°C to 200°C.

8. The method of any one of claims 1 to 7, wherein the conditions include an initial pressure range of 0 psi to 1000 psi (0 atm to 68 atm).

9. The conditions include air, nitrogen (N ２ ), oxygen (O ２ 9. The method of any one of claims 1 to 8, comprising the presence of a gas selected from the group consisting of:

10. 10. The method of any one of claims 1 to 9, wherein the dicarboxylic acid or dicarboxylic acid substituted with at least one nitro group is substituted with one or more methyl groups.

11. 11. The method according to any one of claims 1 to 10, wherein if the dicarboxylic acid comprises an even number n of carbon chains between the two carboxy groups, it is substituted by (n / 2)-1 methyl groups.

12. 12. The method according to any one of claims 1 to 11, wherein if the dicarboxylic acid comprises an odd number n of carbon chains between the two carboxy groups, it is substituted by (n / 2)-1 or (n / 2)-2 methyl groups.

13. The process of any one of claims 1 to 12, further comprising adding at least one solid catalyst to the reaction vessel.

14. 14. The method of any one of claims 1 to 13, further comprising converting the carboxylic acid optionally substituted with a nitro group and / or the dicarboxylic acid optionally substituted with a nitro group into an ester.

15. The method of claim 14, further comprising isolating at least one corresponding ester.

16. The method of any one of claims 1 to 15, wherein the degradation products comprise 2-methylsuccinic acid, 3-methylglutaric acid, 2,4-dimethylglutaric acid, 2,4-dimethyladipic acid, 3,5-dimethylpimelic acid, 2,4,6-trimethylpimelic acid, 2,4,6-trimethylsebacic acid, and 2,4,6,8-tetramethylazelaic acid, or a mixture of salts, esters, or anhydrides thereof.

17. The decomposition product is methylbutanedioic acid dimethyl ester, methylbutanedioic acid dimethyl ester, methylbutanedioic acid dimethyl ester, 2,4-dimethylpentanedioic acid dimethyl ester, 2-formyl-1H-1,4-benzenedicarbonitrile, 2,4-dimethylpentanedioic acid dimethyl ester, 5-acetoxy-3-methylhexanoic acid methyl ester, (R,R)-(-)-2,4-dimethyl-9-decenoic acid methyl ester, 2-methylheptanedioic acid dimethyl ester, 3,5-dimethylheptanedioic acid dimethyl ester, 2-butylquinoline, cyclohexanecarboxylic acid ethyl ester, 3-cyclobut-1-enyl-hydroxy-2-methylpropionic acid methyl ester, adipic acid methyl propyl ester, 2-methyl-3-cyclopropylpropanoic acid methyl ester, 1-cyclopentyl-3-ethoxy-2-propanone, cis-1,2-diethylcyclohexane hexane, 1,2-diethyl-3-methylcyclohexane, 2,2,7,7-tetramethyloctanedioic acid, (2S,4R)-(+)-2,4-dimethyl-9-decenoic acid methyl ester, O-fluoroacetophenone oxime, trans-2-(1-mercapto-1-methylethyl)-5-methylcyclohexanone, dibenzo[b,f]oxepin-3-ylamine, (4-ethoxyphenyl)carbamic acid ethyl ester, 2-( 17. The method of claim 16, further comprising at least one of 1-methyl-1H-imidazol-4-yl)quinoline, 2,8-bis(1,5,5-trimethylpyrrolidine-2,4-dione-3-ylidene)-3,7-diazanonane, 2-amino-3,5,7,8-tetrahydro-4,6-pteridinedione, or 1,2-dimethoxy-4-(1,2-dimethoxyethyl)benzene or salts or esters or anhydrides thereof.

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