Process for upgrading an aromatic waste stream

Abstract

Processes for upgrading heavy aromatic waste streams, including polystyrene and other related materials, to chemical feedstocks are disclosed. Process embodiments include feeding a heavy aromatic waste stream to: a) hydrogenation, followed by steam cracking, followed by separation; and b) separation, followed by: i) hydrogenation, and ii) hydrogenation, followed by steam cracking and separation. Each embodiment can yield ethylene, propylene, ethylbenzene, ethylbenzene precursors, or combinations thereof.

Description

[0001] Cross-references to related applications

[0002] This application is filed pursuant to the Patent Cooperation Treaty, which claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 568,581, filed March 22, 2024, entitled “Process for Upgrading Aromatic Waste Streams,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates generally to the field of chemical recycling, and more specifically to processes for recycling and converting heavy aromatic waste and / or fuel oil streams (including polystyrene and other related materials) back into chemical feedstocks. Background Technology

[0004] The production of styrene and ethylbenzene is a key aspect of the chemical industry, with applications spanning numerous products, including plastics, resins, and rubber. The propylene oxide / styrene monomer (POSM) process is a well-known technology for producing styrene and propylene oxide. However, its reliance on non-renewable resources and the generation of byproducts and waste streams pose environmental and economic challenges.

[0005] Polystyrene waste, due to its non-biodegradable nature and significant environmental problems, has traditionally been addressed through mechanical recycling processes. However, these processes are limited in their ability to achieve complete chemical sphericity and often result in the further recycling of materials. Furthermore, heavy aromatic waste streams, such as residual fuel oil (RFO) and heavy aromatic solvents (HAS), are byproducts of various chemical processes, including the POSM process itself. These waste streams are often underutilized, causing treatment and environmental problems.

[0006] Improved processes are needed to recycle these waste streams back into valuable chemical feedstocks, thereby reducing reliance on virgin feedstocks, improving the sustainability of chemical processes, and contributing to the circular economy. Ideally, such improved processes can be implemented in existing facilities by modifying them with commonly used equipment and familiar technologies, or incorporated into new facilities. Summary of the Invention

[0007] In some embodiments, a process for upgrading a heavy aromatic waste stream to a chemical feedstock includes subjecting the heavy aromatic waste stream to hydrogenation conditions in a first reaction zone to produce a first intermediate product, wherein: i) the heavy aromatic waste stream contains olefins and aromatic unsaturated components; and ii) the first intermediate product is substantially free of olefinic unsaturated components and has a reduced amount of aromatic unsaturated components. The process further includes subjecting the first intermediate product to steam cracking conditions in a second reaction zone to produce a second intermediate product. The second intermediate product is then separated to produce a third intermediate product comprising ethylene, propylene, or a combination thereof, and a first residual fraction.

[0008] In some embodiments, a process for upgrading a heavy aromatic waste stream to a chemical feedstock includes separating the heavy aromatic waste stream to produce a first intermediate product comprising styrene and a first residual fraction. The process further includes subjecting the first intermediate product to hydrogenation conditions in a first reaction zone to produce a second intermediate product comprising ethylbenzene. The first residual fraction is then hydrogenated in a second reaction zone to produce a third intermediate product, wherein: i) the first heavy fraction comprises olefins and aromatic unsaturated components; and ii) the third intermediate product substantially excludes olefin unsaturated components and has reduced amounts of aromatic unsaturated components. The process further includes subjecting the third intermediate product to steam cracking conditions in a third reaction zone to produce a fourth intermediate product. The fourth intermediate product is then separated to produce a fifth intermediate product comprising ethylene, propylene, or a combination thereof, and a second residual fraction.

[0009] The features and technical advantages of the invention have been outlined quite extensively above to facilitate a better understanding of the detailed description thereof below. Other features and advantages of the invention will be described below, forming the subject matter of the claims. Those skilled in the art will understand that the disclosed concepts and specific embodiments can readily be used as a basis for improving or designing other catalyst compositions and / or processes for carrying out the same purposes of the invention. Those skilled in the art will also recognize that such equivalent structures do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features, along with additional objects and advantages, that are considered characteristic of the invention, relating to both its compositions and processes, will be better understood from the following description. Attached Figure Description

[0010] The claimed subject matter can be understood by referring to the following description in conjunction with the accompanying drawings, in which the same reference numerals denote the same elements, and wherein:

[0011] Figure 1This is a simplified flow chart according to an embodiment of the present disclosure, illustrating the hydrogenation of heavy aromatic waste feed to remove olefins and aromatic unsaturated components to produce a first intermediate product, steam cracking of the first intermediate product to produce a second intermediate product comprising ethylene and / or propylene, and separation of ethylene and / or propylene suitable as feedstock or feedstock precursors for use in the POSM and / or SM production processes; and

[0012] Figure 2 The following is a simplified flowchart of an embodiment of the present disclosure, illustrating the separation of heavy aromatic waste feed to produce a first intermediate and a first residual product with increased styrene content, hydrogenation of the first intermediate to produce EB suitable as a feedstock for the propylene oxide / styrene monomer (POSM) process or for direct conversion to styrene monomer (SM) via dehydrogenation, hydrogenation of the first residual to remove olefinic and aromatic unsaturated components to produce a second intermediate, steam cracking of the second intermediate to produce a third intermediate comprising ethylene and / or propylene, and separation of ethylene and / or propylene suitable as feedstock or feedstock precursor for the POSM and / or SM production processes.

[0013] While the disclosed processes and compositions are readily modified and substituted, the accompanying drawings illustrate specific embodiments described in detail herein by way of example. However, it should be understood that the description of specific embodiments herein is not intended to limit the invention to the particular forms disclosed; rather, the invention is intended to cover all modifications, equivalents, and substitutions falling within the spirit and scope of the invention as defined by the appended claims. Detailed Implementation

[0014] Illustrative embodiments of the claimed subject matter will now be disclosed. For clarity, some features of actual implementations may not be described in this specification. It should be understood that in the development of any such actual implementation, many implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from implementation to implementation. Furthermore, it should be understood that such development efforts, even if complex and time-consuming, are routine tasks for those skilled in the art who benefit from this disclosure.

[0015] The words and phrases used herein should be understood and interpreted in accordance with the understanding of those words and phrases by one of skill in the art. A specific definition of a term or phrase, that is, a definition that differs from the common and customary meaning understood by one of skill in the art, is required. Such specific or clear definition, which is intended to have a specific meaning that differs from the broadest meaning understood by one of skill in the art, will be explicitly stated in the specification by providing such specific or clear definition of the term or phrase.

[0016] For example, the following discussion includes a non-exhaustive list of definitions for several specific terms used in this disclosure (other terms may be defined or clarified in the manner defined elsewhere herein). These definitions are intended to clarify the meaning of the terms used herein. Terms are believed to be used in accordance with their usual meaning, but definitions are provided herein for clarity.

[0017] definition

[0018] As used herein, when the term “comprising” is used in conjunction with the claims or description, “a” or “an” means one or more, unless the context otherwise requires.

[0019] As used herein, “about” means the stated value plus or minus the measurement error limit or plus or minus 10% (if the measurement process is not indicated).

[0020] As used herein, “consistent with…” does not include additional material elements, but may include non-material elements that do not substantially alter the performance of the invention.

[0021] As used in this article, “composed of” is a closed phrase and excludes all other elements.

[0022] As used in this article, “conversion rate” is used to represent the percentage of feed components that disappear throughout the reactor.

[0023] As used herein, “comprising” should be interpreted as specifying the presence of the mentioned feature, whole, step, or component, but does not preclude the presence or addition of one or more features, wholes, steps, or components, or combinations thereof. Furthermore, each of the terms “comprising,” “comprises,” “comprised of,” “include,” “includes,” “included,” “involving,” “involves,” “involved,” and “for example” is used in its open, non-limiting sense and may be used interchangeably. Additionally, the term “comprising” is intended to include examples and aspects covered by the terms “substantially composed of” and “composed of.” Similarly, the term “substantially composed of” is intended to include examples covered by the term “composed of.”

[0024] As used herein, a "reaction zone" refers to a chamber that is fully enclosed to maintain selected operating conditions to produce the desired reaction, such as a pyrolysis reaction zone, a steam cracking reaction zone, a catalytic cracking reaction zone, or a hydrogenation reaction zone. In some embodiments, each reaction zone may be a separate reactor. In some embodiments, a single vessel may contain multiple reaction zones.

[0025] As used herein, “separation conditions” or “separation section” refers to the facilities required to recover specific materials from the intermediates and / or reaction products disclosed herein, including distillation, absorption, adsorption, membrane separation, cryogenic distillation, extractive distillation, azeotropic distillation, steam distillation, molecular sieving, liquid-liquid extraction (solvent extraction), decantation, centrifugation, or combinations thereof. Such embodiments will include general equipment associated with the aforementioned separation processes, including but not limited to towers, drums, vessels, heat exchangers, pumps, valves, reflux loops, etc., the descriptions of which are omitted herein for simplicity. When the intermediates and / or reaction products disclosed herein are defined as comprising multiple products (e.g., benzene, ethylene, propylene, or combinations thereof), “separation conditions” or “separation section” are intended to include the ability to individually recover each of those products with a desired purity (e.g., 99 wt% benzene, 99.5 wt% ethylene, 97 wt% propylene, etc.), the desired purity being required by arranging the products as feed to different locations in other processes (e.g., but not limited to, POSM and / or SM).

[0026] As used in this article, “waste stream” is a type of feed stream that includes materials that have been discarded and are no longer useful, including but not limited to post-consumer and post-industrial waste.

[0027] As used herein, "zeolite" refers to an aluminosilicate mineral with a microporous structure. In one respect, zeolite can be used as a catalyst in the processes disclosed herein. Zeolite can occur naturally or can be produced industrially.

[0028] Unless otherwise specified, all concentrations in this document are expressed as weight percentages (“wt%”).

[0029] The following abbreviations are used in this article:

[0030] ECR Ethylene cracking residue HAS Heavy aromatic solvents PAH Polycyclic aromatic hydrocarbons PFO Pyrolysis fuel oil POSM Propylene oxide / styrene monomer production process RFO Residual fuel oil SM The styrene monomer or the process for producing styrene monomer depends on the context. WHSV Heavy space speed

[0031] Heavy aromatic waste

[0032] This disclosure provides a process for upgrading aromatic waste comprising polystyrene to light olefins (e.g., ethylene and / or propylene), ethylbenzene, and / or ethylbenzene precursors, said ethylbenzene precursors being usable as feedstocks in petrochemical processes, including but not limited to propylene oxide / styrene monomer processes and ethylbenzene dehydrogenation, oxidation, or non-oxidation to produce styrene. Heavy aromatic waste streams include, but are not limited to, polystyrene pyrolysis oil, styrene, heavy polystyrene pyrolysis oil, heavy residual fuel oil (RFO), heavy aromatic solvents (HAS), pyrolysis fuel oil (PFO), and ethylene cracking residues (ECR). The heavy aromatic waste stream to be treated by the process disclosed herein can be any one of the foregoing materials or any mixture of two or more of the foregoing materials.

[0033] Polystyrene pyrolysis involves the thermal degradation of polystyrene (a common thermoplastic material) in the absence of oxygen. This process breaks down the long polymer chains of polystyrene into shorter hydrocarbon chains and styrene monomers, along with a range of other hydrocarbons. The products of polystyrene pyrolysis can be broadly classified into two groups: polystyrene pyrolysis oil and polystyrene pyrolysis oil heavy fractions. Each of these categories has different properties and potential applications. Polystyrene pyrolysis oil is primarily composed of styrene monomers, which can be recycled and purified for reuse in the production of new polystyrene products or other styrene-based polymers. In addition to styrene, the oil contains other aromatic hydrocarbons such as toluene, ethylbenzene, and benzene, as well as mixtures of aliphatic hydrocarbons. The exact composition of the pyrolysis oil can vary based on pyrolysis conditions such as temperature, heating rate, and the presence of a catalyst. Polystyrene pyrolysis oil heavy fractions consist of heavier, more complex hydrocarbons produced during pyrolysis. These compounds have higher molecular weights compared to the main fraction of the pyrolysis oil and typically include polycyclic aromatic hydrocarbons (PAHs), as well as various oligomers formed through partial recombination of the degradation products. Pyrolysis of polystyrene offers an opportunity to recycle plastics that would otherwise be difficult to process through mechanical recycling methods. By converting waste polystyrene into valuable chemicals and fuels, pyrolysis can reduce landfill and incineration, contributing to circular economy initiatives.

[0034] During the POSM process, various byproducts are generated, including residual fuel oil (RFO) rich in aromatic compounds. These RFOs are complex mixtures containing high molecular weight hydrocarbons (primarily aromatic compounds) as well as aliphatic compounds and small amounts of olefins. The aromatic compound content gives these oils their unique properties, including high density and high calorific value. The exact composition of these oils can vary depending on the details of the POSM process and the feedstock used. Due to the presence of large, complex hydrocarbon molecules, these oils have high boiling points. The high aromatic compound content contributes to higher density and viscosity compared to lighter fuel oils. While these oils have high energy content, their high aromatic compound content can affect their combustion characteristics. Depending on the feedstock and process conditions, the sulfur content can vary, potentially requiring desulfurization treatment for certain applications. This RFO can be used as a component in fuel oil and asphalt blends, but its high aromatic compound content and / or emissions such as NOx, SOx, and particulate matter raise some safety, environmental, and regulatory considerations.

[0035] Benzene is typically converted to ethylbenzene by reacting benzene with ethylene in an alkylation process. Heavy aromatic solvents (HAS) can be generated as byproducts of the alkylation process. These HAS typically consist of higher molecular weight aromatic compounds formed as a side reaction during alkylation. A common HAS generated in this context is diethylbenzene (DEB), which consists of three isomers: ortho-, meta-, and para-diethylbenzene. When an ethyl group is added to ethylbenzene in a subsequent alkylation reaction, diethylbenzene is formed, which essentially represents the over-alkylation of benzene. While DEB has some direct uses, it is desirable to break down these heavy molecules and convert them into base monomers suitable as feedstocks for a variety of petrochemical processes, including but not limited to POSM and EB dehydrogenation to SM.

[0036] In steam cracking processes, in addition to producing olefins (e.g., ethylene, propylene), a complex mixture of byproducts is generated. Such byproducts include high molecular weight hydrocarbons rich in heavy aromatics, such as pyrolysis fuel oil (PFO) and ethylene cracking residue (ECR). PFO is a complex mixture containing heavy aromatics, asphaltenes, and other hydrocarbons produced during the thermal cracking of naphtha or gas oil. Its exact composition varies depending on the feedstock and cracker operating conditions, but it is characterized by its high content of polycyclic aromatic hydrocarbons (PAHs). ECR is a residue left from the steam cracking process, particularly when using heavier feedstocks. It is rich in heavy aromatics, tar, and coke precursors. Like PFO, its specific composition depends on the feedstock and process conditions. Similar to RFO, PFO and ECR can be used as components in fuel oils, but their high aromatic content and / or emissions such as NOx, SOx, and particulate matter raise some safety, environmental, and regulatory considerations.

[0037] This disclosure provides embodiments of a process for upgrading a heavy aromatic waste stream, comprising polystyrene and other related materials, into a chemical feedstock. In some embodiments, the heavy aromatic waste stream comprises polystyrene pyrolysis oil, styrene, heavy polystyrene pyrolysis oil residue, heavy residual fuel oil (RFO), heavy aromatic solvent (HAS), pyrolysis fuel oil (PFO), ethylene cracking residue (ECR), or combinations thereof. In some embodiments, based on the total weight of the heavy aromatic waste stream, the heavy aromatic waste stream includes styrene in amounts greater than or equal to 30 wt%, greater than or equal to 40 wt%, greater than or equal to 50 wt%, or greater than or equal to 60 wt%.

[0038] Including steam cracking / hydrogenation processes

[0039] Figure 1 A process 100 for upgrading a heavy aromatic waste stream 102 into a chemical feedstock is shown. The heavy aromatic waste stream 102 has a first styrene content. Process conditions and catalyst selection are optimized to obtain the desired product composition. In some embodiments, process 100 includes subjecting the heavy aromatic waste stream 102 to hydrogenation conditions in a first reaction zone 140 to produce a first intermediate product 141, wherein the heavy aromatic waste stream 102 contains olefins and aromatic unsaturated components, and the first intermediate product 141 is substantially free of olefin unsaturated components and has a reduced amount of aromatic unsaturated components. Examples of hydrogenation catalysts include any commercial hydrogenation catalyst known in the art, such as NiMo, CoMo, Ni, Pd, Pt, Cu, etc. The first intermediate product 141 is subjected to steam cracking conditions in a second reaction zone 150 to produce a second intermediate product 151. Steam cracking is described in U.S. Patent Nos. 2,847,366, 3,597,494, 4,832,822, 4,780,196, and 11,046,898; and U.S. Patent Application Publications Nos. 2011 / 0073524, 2014 / 0083906, and 2008 / 0194900, the disclosures of which are incorporated herein by reference in their entirety. The second intermediate 151 is subjected to separation conditions 130 to produce a third intermediate 131 comprising ethylene, propylene, or a combination thereof, and a first residual fraction 132.

[0040] The third intermediate product 131 is then fed into the POSM / SM process 190, where POSM / SM refers to the POSM process and / or the SM process. The SM process refers to the direct dehydrogenation of EB to form styrene monomer. The third intermediate product 131 contains one or more of styrene, benzene, ethylene, and propylene. As part of the POSM / SM process 190, one or more of styrene, benzene, ethylene, and propylene are recovered from the third intermediate product 131, wherein the purity of the recovered styrene, benzene, ethylene, and propylene is suitable for direct or indirect addition to the POSM and / or SM processes. Indirect addition means that the recovered stream may be subjected to one or more additional treatment steps to make it suitable for addition to the POSM and / or SM processes. The specific components in the heavy aromatic waste stream 102, the specific hydrogenation conditions in the first reaction zone 140, the specific steam cracking conditions in the second reaction zone 150, and the specific separation conditions in the separation section 130 will produce varying amounts of styrene, benzene, ethylene, and / or propylene in the third intermediate product 131. Examples of hydrogenation catalysts include any commercially available hydrogenation catalysts known in the art, such as NiMo, CoMo, Ni, Pd, Pt, Cu, etc.

[0041] In some embodiments, styrene is recovered from the third intermediate 131. The styrene is hydrogenated to form EB. Examples of hydrogenation catalysts include any commercially available hydrogenation catalyst known in the art, such as NiMo, CoMo, Ni, Pd, Pt, Cu, etc. In some embodiments, at least a portion of the EB is added to the POSM process, where the EB is oxidized to form ethylbenzene hydroperoxide. The ethylbenzene hydroperoxide is then catalytically reacted with propylene to form propylene oxide and 1-phenylethanol. The 1-phenylethanol is subsequently dehydrated to produce styrene monomer. In some embodiments, at least a portion of the EB is added to the SM process, where the EB is dehydrogenated to produce styrene monomer. In some embodiments, the EB is added to both the POSM and SM processes.

[0042] In some embodiments, benzene is recovered from the third intermediate 131. Benzene is reacted with ethylene to form EB. In some embodiments, at least a portion of EB is added to the POSM process, where EB is oxidized to form ethylbenzene hydroperoxide. The ethylbenzene hydroperoxide is then catalytically reacted with propylene to form propylene oxide and 1-phenylethanol. The 1-phenylethanol is subsequently dehydrated to produce styrene monomer. In some embodiments, at least a portion of EB is added to the SM process, where EB is dehydrogenated to produce styrene monomer. In some embodiments, EB is added to both the POSM and SM processes.

[0043] In some embodiments, ethylene is recovered from the third intermediate 131. The ethylene is reacted with benzene to form EB. In some embodiments, at least a portion of the EB is added to the POSM process, where the EB is oxidized to form ethylbenzene hydroperoxide. The ethylbenzene hydroperoxide is then catalytically reacted with propylene to form propylene oxide and 1-phenylethanol. The 1-phenylethanol is subsequently dehydrated to produce styrene monomer. In some embodiments, at least a portion of the EB is added to the SM process, where the EB is dehydrogenated to produce styrene monomer. In some embodiments, EB is added to both the POSM and SM processes.

[0044] In some embodiments, propylene is recovered from the third intermediate 131. Propylene is then fed into the POSM process, where it reacts with ethylbenzene hydroperoxide to form propylene oxide and 1-phenylethanol. The 1-phenylethanol is subsequently dehydrated to produce styrene monomer.

[0045] In some embodiments, the first residual fraction 132 is added as an additional feed to the second reaction zone 150 via stream 133, and discharged from the process via stream 134 for further processing, or a combination thereof.

[0046] Figure 2 A process 200 is shown for upgrading a heavy aromatic waste stream 202 into a chemical feedstock. The heavy aromatic waste stream 202 has a first styrene content, a first benzene content, a first ethylene content, a first propylene content, or a combination thereof. Process 200 includes subjecting the heavy aromatic waste stream 202 to separation conditions 230 to produce a first intermediate product 231 and a first residual fraction 232. Process conditions and catalyst selection are optimized to obtain the desired product composition. In some embodiments, the first intermediate product 231 has a second styrene content less than the first styrene content, a second benzene content less than the first benzene content, a second ethylene content less than the first styrene content, a second propylene content less than the first propylene content, or a combination thereof. The first intermediate product 231 is subjected to hydrogenation conditions in a first reaction zone 240 to produce a second intermediate product 241 comprising EB. Examples of hydrogenation catalysts include any commercially available hydrogenation catalyst known in the art, such as NiMo, CoMo, Ni, Pd, Pt, Cu, etc. EB is recovered from the second intermediate product 241. At least a portion of the EB is: a) oxidation to form ethylbenzene hydroperoxide, catalytic reaction of the ethylbenzene hydroperoxide with propylene to form propylene oxide and 1-phenylethanol, and dehydration of the 1-phenylethanol to produce styrene monomer; b) dehydrogenation to produce styrene monomer; or c) a combination thereof.

[0047] The first residual fraction 232 is subjected to hydrogenation conditions in the second reaction zone 245 to produce a third intermediate 246, wherein the first residual fraction 232 comprises olefinic and aromatic unsaturated components, and the third intermediate 246 is substantially free of olefinic unsaturated components and has a reduced amount of aromatic unsaturated components. Examples of hydrogenation catalysts include any commercially available hydrogenation catalyst known in the art, such as NiMo, CoMo, Ni, Pd, Pt, Cu, etc. The third intermediate 246 is subjected to steam cracking conditions in the third reaction zone 250 to produce a fourth intermediate 251. The fourth intermediate 251 is subjected to separation conditions 235 to produce a fifth intermediate 236 comprising ethylene, propylene, benzene, or combinations thereof, and a second residual fraction 237.

[0048] In some embodiments, benzene is recovered from the fifth intermediate 236. Benzene is reacted with ethylene to form EB. In some embodiments, at least a portion of EB is added to the POSM process, where EB is oxidized to form ethylbenzene hydroperoxide. The ethylbenzene hydroperoxide is then catalytically reacted with propylene to form propylene oxide and 1-phenylethanol. The 1-phenylethanol is subsequently dehydrated to produce styrene monomer. In some embodiments, at least a portion of EB is added to the SM process, where EB is dehydrogenated to produce styrene monomer. In some embodiments, EB is added to both the POSM and SM processes.

[0049] In some embodiments, ethylene is recovered from the fifth intermediate 236. The ethylene is reacted with benzene to form EB. In some embodiments, at least a portion of the EB is added to the POSM process, where the EB is oxidized to form ethylbenzene hydroperoxide. The ethylbenzene hydroperoxide is then catalytically reacted with propylene to form propylene oxide and 1-phenylethanol. The 1-phenylethanol is subsequently dehydrated to produce styrene monomer. In some embodiments, at least a portion of the EB is added to the SM process, where the EB is dehydrogenated to produce styrene monomer. In some embodiments, EB is added to both the POSM and SM processes.

[0050] In some embodiments, propylene is recovered from the fifth intermediate 236. Propylene is then fed into the POSM process, where it reacts with ethylbenzene hydroperoxide to form propylene oxide and 1-phenylethanol. The 1-phenylethanol is subsequently dehydrated to produce styrene monomer.

[0051] The third intermediate product 231 is then fed into the POSM / SM process 290, where POSM / SM refers to the POSM process and / or the SM process. The SM process refers to the direct dehydrogenation of EB to form styrene monomer. The third intermediate product 231 contains one or more of styrene, benzene, ethylene, and propylene. As part of the POSM / SM process 290, one or more of styrene, benzene, ethylene, and propylene are recovered from the third intermediate product 231, wherein the purity of the recovered styrene, benzene, ethylene, and propylene is suitable for direct or indirect addition to the POSM and / or SM processes. Indirect addition means that the recovered stream may be subjected to one or more additional treatment steps to make it suitable for addition to the POSM and / or SM processes. The specific components in the heavy aromatic waste stream 202, the specific hydrogenation conditions in the first reaction zone 240, the specific steam cracking conditions in the second reaction zone 250, and the specific separation conditions in the separation section 230 will produce varying amounts of styrene, benzene, ethylene, and / or propylene in the third intermediate product 231. Examples of hydrogenation catalysts include any commercially available hydrogenation catalysts known in the art, such as NiMo, CoMo, Ni, Pd, Pt, Cu, etc.

[0052] In some embodiments, styrene is recovered from the third intermediate 231. The styrene is hydrogenated to form EB. In some embodiments, at least a portion of the EB is added to the POSM process, where the EB is oxidized to form ethylbenzene hydroperoxide. The ethylbenzene hydroperoxide is then catalytically reacted with propylene to form propylene oxide and 1-phenylethanol. The 1-phenylethanol is subsequently dehydrated to produce styrene monomer. In some embodiments, at least a portion of the EB is added to the SM process, where the EB is dehydrogenated to produce styrene monomer. In some embodiments, EB is added to both the POSM and SM processes.

[0053] In some embodiments, benzene is recovered from the third intermediate 231. Benzene is reacted with ethylene to form EB. In some embodiments, at least a portion of EB is added to the POSM process, where EB is oxidized to form ethylbenzene hydroperoxide. The ethylbenzene hydroperoxide is then catalytically reacted with propylene to form propylene oxide and 1-phenylethanol. The 1-phenylethanol is subsequently dehydrated to produce styrene monomer. In some embodiments, at least a portion of EB is added to the SM process, where EB is dehydrogenated to produce styrene monomer. In some embodiments, EB is added to both the POSM and SM processes.

[0054] In some embodiments, ethylene is recovered from the third intermediate 231. The ethylene is reacted with benzene to form EB. In some embodiments, at least a portion of the EB is added to the POSM process, where the EB is oxidized to form ethylbenzene hydroperoxide. The ethylbenzene hydroperoxide is then catalytically reacted with propylene to form propylene oxide and 1-phenylethanol. The 1-phenylethanol is subsequently dehydrated to produce styrene monomer. In some embodiments, at least a portion of the EB is added to the SM process, where the EB is dehydrogenated to produce styrene monomer. In some embodiments, EB is added to both the POSM and SM processes.

[0055] In some embodiments, propylene is recovered from the third intermediate 231. Propylene is then fed into the POSM process, where it reacts with ethylbenzene hydroperoxide to form propylene oxide and 1-phenylethanol. The 1-phenylethanol is subsequently dehydrated to produce styrene monomer.

[0056] In some embodiments, the second residual fraction 237 is added as an additional feed to the third reaction zone 250 via stream 238, and discharged from the process via stream 239 for further processing, or a combination thereof.

[0057] Some implementation schemes

[0058] Implementation Scheme A1. A process for upgrading heavy aromatic waste streams into chemical feedstocks, the process comprising:

[0059] a) subjecting the heavy aromatic waste stream to hydrogenation conditions in a first reaction zone to produce a first intermediate product, wherein:

[0060] i) The heavy aromatic waste stream includes olefins and aromatic unsaturated components; and

[0061] ii) The first intermediate product substantially does not contain olefinic unsaturated components and has a reduced amount of aromatic unsaturated components;

[0062] b) subjecting the first intermediate product to steam cracking conditions in the second reaction zone to produce the second intermediate product; and

[0063] c) Separate the second intermediate product to produce a third intermediate product comprising ethylene, propylene, or a combination thereof, and a first residual fraction.

[0064] Implementation scheme A2. The process of implementation scheme A1 also includes:

[0065] a) recovering the ethylene from the third intermediate product; and

[0066] b) React the ethylene with benzene to form ethylbenzene.

[0067] Implementation scheme A3. The process of implementation scheme A1 or A2 also includes:

[0068] a) Oxidize at least a portion of the ethylbenzene to form ethylbenzene hydroperoxide, catalytically react the ethylbenzene hydroperoxide with propylene to form propylene oxide and 1-phenylethanol, and dehydrate the 1-phenylethanol to produce styrene monomer;

[0069] b) Dehydrogenating at least a portion of the ethylbenzene to produce styrene monomer; or

[0070] c) Its combination.

[0071] Implementation Scheme A4. The process of any one of Implementation Schemes A1-A3 further includes:

[0072] a) Recover the propylene from the third intermediate product;

[0073] b) Catalytically reacting the propylene with ethylbenzene hydroperoxide to form propylene oxide and 1-phenylethanol; and

[0074] c) Dehydrate 1-phenylethanol to produce styrene monomer.

[0075] Implementation Scheme A5. The process of any one of Implementation Schemes A1-A4 further includes:

[0076] a) At least a portion of the first residual fraction is added as additional feed to the second reaction zone;

[0077] b) Send at least a portion of the first residual fraction outside the process for further processing; or

[0078] c) Its combination.

[0079] Implementation Scheme B1. A process for upgrading heavy aromatic waste streams into chemical feedstocks, the process comprising:

[0080] a) Separate the heavy aromatic waste stream to produce a first intermediate product comprising styrene and a first residual fraction;

[0081] b) subjecting the first intermediate product to hydrogenation conditions in a first reaction zone to produce a second intermediate product comprising ethylbenzene;

[0082] c) subjecting the first residual fraction to hydrogenation conditions in the second reaction zone to produce a third intermediate product, wherein:

[0083] i) The first heavy fraction includes olefins and aromatic unsaturated components; and

[0084] ii) The third intermediate product substantially does not contain olefinic unsaturated components and has a reduced amount of aromatic unsaturated components;

[0085] d) subjecting the third intermediate to steam cracking conditions in a third reaction zone to produce a fourth intermediate; and

[0086] e) Separate the fourth intermediate to produce a fifth intermediate comprising benzene, ethylene, propylene, or a combination thereof, and a second residual fraction.

[0087] Implementation Scheme B2. The process of Implementation Scheme B1, the process further comprising recovering ethylbenzene from the second intermediate product, and:

[0088] a) Oxidize at least a portion of the ethylbenzene to form ethylbenzene hydroperoxide, catalytically react the ethylbenzene hydroperoxide with propylene to form propylene oxide and 1-phenylethanol, and dehydrate the 1-phenylethanol to produce styrene monomer;

[0089] b) Dehydrogenating at least a portion of the ethylbenzene to produce styrene monomer; or

[0090] c) Its combination.

[0091] Implementation scheme B3. The process of implementation scheme B1 or B2 also includes:

[0092] a) Recovering the ethylene from the fifth intermediate product; and

[0093] b) React the ethylene with benzene to form ethylbenzene.

[0094] Implementation Scheme B4. The process of any one of Implementation Schemes B1-B3 further includes:

[0095] a) Oxidize the ethylbenzene to form ethylbenzene hydroperoxide;

[0096] b) Catalytically reacting the ethylbenzene hydroperoxide with propylene to form propylene oxide and 1-phenylethanol; and

[0097] c) Dehydrate 1-phenylethanol to produce styrene monomer.

[0098] Implementation Scheme B5. The process of any one of Implementation Schemes B1-B4 further includes:

[0099] a) Recover the propylene from the fifth intermediate product;

[0100] b) Catalytically reacting the propylene with ethylbenzene hydroperoxide to form propylene oxide and 1-phenylethanol; and

[0101] c) Dehydrate 1-phenylethanol to produce styrene monomer.

[0102] Implementation Scheme B6. The process of any one of Implementation Schemes B1-B5 further includes:

[0103] a) recovering the benzene from the third intermediate or the fourth intermediate; and

[0104] b) React the benzene with ethylene to form ethylbenzene.

[0105] Implementation scheme B7. The process of implementation scheme B6 also includes:

[0106] a) Oxidize at least a portion of the ethylbenzene to form ethylbenzene hydroperoxide, catalytically react the ethylbenzene hydroperoxide with propylene to form propylene oxide and 1-phenylethanol, and dehydrate the 1-phenylethanol to produce styrene monomer;

[0107] b) Dehydrogenating at least a portion of the ethylbenzene to produce styrene monomer; or

[0108] c) Its combination.

[0109] Implementation Scheme B8. The process of any one of Implementation Schemes B1-B7 further includes:

[0110] a) At least a portion of the second residual fraction is added as additional feed to the third reaction zone;

[0111] b) Send at least a portion of the first residual fraction outside the process for further processing; or

[0112] c) Its combination.

[0113] The process disclosed in this invention is illustrated in the following examples. These examples are included to illustrate embodiments of the appended claims. However, these are merely exemplary, and the invention can be broadly applied to embodiments not shown in the examples. Those skilled in the art will understand that many changes can be made to the specific embodiments disclosed without departing from the spirit and scope of this disclosure, and the same or similar results can still be obtained. The following examples should in no way be construed as limiting or restricting the scope of the appended claims.

[0114] Example

[0115] The following embodiments are included to illustrate implementations of the present invention. Those skilled in the art will understand that the techniques disclosed in the following embodiments represent techniques discovered by the inventors that work well in the practice of the present invention and can therefore be considered as constituting a preferred mode of practice. However, based on this disclosure, those skilled in the art will understand that many changes can be made to the specific embodiments disclosed without departing from the spirit and scope of the invention, and the same or similar results can still be obtained.

[0116] background

[0117] Characterization of liquid products: The liquid products from the two traps were characterized by gas chromatography (GC) and proton NMR ( 1 H NMR).

[0118] GC analysis of the liquid products for each run was performed using an Agilent 7890 GC (Agilent Technologies, Santa Clara, CA) equipped with a standard non-polar column and a flame ionization detector. For the GC data, the weight percentages of x < nC7 (boiling point < 98°C, designated as LF1), nC7 < x < nC11 (boiling point 98°C < BP < 203°C, designated as LF2), nC12 < x < nC28 (boiling point 203°C < BP < 434°C, designated as LF3), and x > C28 (boiling point > 434°C, designated as LF4) were used to characterize the liquid products.

[0119] NMR data were used to characterize the percentages of aromatic protons, paraffinic protons and olefinic protons in the liquid products. The examples were analyzed with the addition of CDCl3 (0.6 g of the depolymerized polymer / metal oxide mixture with 0.4 g of CDCl3). Data were collected on a Bruker AV500 MHz NMR spectrometer (Bruker Corporation, Billerica, MA) at 25°C using a 5 mm Prodigy probe. One-dimensional 1H NMR data were processed with TOPSPIN® software (Bruker) using an exponential line broadening window function. Quantitative measurements were performed with a 15-second relaxation delay, a 30° flip angle pulse, and 32 scans to facilitate accurate integration. Spectral integrals for aromatic, olefinic and paraffinic protons were obtained and used to quantify the relative proportions of these protons.

[0120] FTIR process

[0121] FTIR spectroscopy was performed as follows. FTIR spectra acquisition was carried out using an iS50 FTIR spectrometer equipped with a DTGS detector from Thermo Scientific. The sample compartment was fitted with an attenuated total reflection (ATR) accessory. The ATR cell was obtained from Pike Technologies and was equipped with a 3-ounce zinc selenide (ZnSe) crystal. The analysis required a sample volume of approximately 0.05 mL. Those skilled in FTIR spectroscopy will recognize that when multiple spectra are overlaid in the same graph, these spectra can be represented with similar baselines or offset baselines. This choice is purely for optimal observation of the occurring changes and does not affect peak height or peak absorbance measurements, as such measurements are taken from the baseline to the top of the peak.

[0122] hydrogenation

[0123] Table 3 shows the effectiveness of the pyrolysis products of hydrogenated polystyrene pyrolysis heavies. For the polystyrene pyrolysis product samples, 1 H NMR measurements were performed before and after hydrogenation using the NiMo-S (KL-8234) catalyst. The results show a reduction of olefinic and aromatic double bonds after hydrogenation.

[0124] Table 3

[0125] sample saturation Oxygen compounds olefins styrene double bond Fangzu aldehyde Starting materials 62.002 2.159 2.7475 1.5939 31.3861 0.1114 hydrogenated materials 71.315 0.9257 0.463 0.1905 27.1028 0.003

[0126] Table 4 shows the yield of product compositions produced by hydrogenation of a liquid feed comprising 10 wt% pyrolysis oil obtained from the pyrolysis of polystyrene and 90 wt% decahydronaphthalene used as a diluent. A stainless steel continuous packed bed reactor loaded with 3 grams of sulfided NiMo catalyst (NiMo-S) was used to hydrogenate the liquid feed flowing through the catalyst bed at a flow rate of 0.025 mL / min and a hydrogen (H₂) flow rate of 100 sccm. The results show complete conversion of styrene, with greater than 98% of the styrene present in the feed converted to ethylbenzene. GC analysis of the product composition was performed using an Agilent 7890 GC (Agilent Technologies, Santa Clara, CA) equipped with a standard non-polar column and a flame ionization detector. For the GC data, the weight percentages of x < nC7 (boiling point < 98°C, designated as LF1), nC7 < x < nC11 (boiling point 98°C < BP < 203°C, designated as LF2), nC12 < x < nC28 (boiling point 203°C < BP < 434°C, designated as LF3), and x > C28 (boiling point > 434°C, designated as LF4) were used to characterize the products.

[0127] Table 4

[0128] Components Ethylbenzene Ethylcyclohexane styrene Heavy matter Yield (mol%) 60% 1% 0% 39%

[0129] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, in addition to the recited ranges, any lower limit may be combined with any upper limit to recite ranges that are not explicitly recited, ranges from any lower limit may be combined with any other lower limit to recite ranges that are not explicitly recited, and in the same manner, ranges from any upper limit may be combined with any other upper limit to recite ranges that are not explicitly recited. In addition, each point or individual value between the endpoints of a range is included within that range, even if not explicitly recited. Accordingly, each point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit to recite ranges that are not explicitly recited.

[0130] While the invention and its advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Furthermore, the scope of this application is not intended to be limited to the specific embodiments of the processes, machines, equipment, procedures, and / or steps described in the specification. From the disclosure of this invention, those skilled in the art will readily understand that, according to the invention, existing or later-developed processes, machines, equipment, procedures, and / or steps can be utilized to perform substantially the same functions or achieve substantially the same results as the corresponding embodiments described herein. Therefore, the appended claims are intended to include such processes, machines, equipment, procedures, and / or steps within their scope.

Claims

1. A process for upgrading heavy aromatic waste streams into chemical raw materials, the process comprising: a) subjecting the heavy aromatic waste stream to hydrogenation conditions in a first reaction zone to produce a first intermediate product, wherein: i) The heavy aromatic waste stream includes olefins and aromatic unsaturated components; and ii) The first intermediate product substantially does not contain olefinic unsaturated components and has a reduced amount of aromatic unsaturated components; c) subjecting the first intermediate product to steam cracking conditions in the second reaction zone to produce the second intermediate product; and d) Separate the second intermediate product to produce a third intermediate product comprising ethylene, propylene, or a combination thereof, and a first residual fraction.

2. The process according to claim 1 further includes: a) Recover the ethylene from the third intermediate product; as well as b) React the ethylene with benzene to form ethylbenzene.

3. The process according to claim 2 further includes: a) Oxidize at least a portion of the ethylbenzene to form ethylbenzene hydroperoxide, catalytically react the ethylbenzene hydroperoxide with propylene to form propylene oxide and 1-phenylethanol, and dehydrate the 1-phenylethanol to produce styrene monomer; b) Dehydrogenating at least a portion of the ethylbenzene to produce styrene monomer; or c) Its combination.

4. The process according to claim 1 further includes: a) Recover the propylene from the third intermediate product; b) Catalytically react the propylene with ethylbenzene hydroperoxide to form propylene oxide and 1-phenylethanol; as well as c) Dehydrate 1-phenylethanol to produce styrene monomer.

5. The process according to claim 1, further comprising: a) At least a portion of the first residual fraction is added as additional feed to the second reaction zone; b) Send at least a portion of the first residual fraction outside the process for further processing; or c) Its combination.

6. A process for upgrading heavy aromatic waste streams into chemical feedstocks, the process comprising: a) Separate the heavy aromatic waste stream to produce a first intermediate product comprising styrene and a first residual fraction; b) subjecting the first intermediate product to hydrogenation conditions in a first reaction zone to produce a second intermediate product comprising ethylbenzene; c) subjecting the first residual fraction to hydrogenation conditions in the second reaction zone to produce a third intermediate product, wherein: i) The first heavy fraction includes olefins and aromatic unsaturated components; and ii) The third intermediate product substantially does not contain olefinic unsaturated components and has a reduced amount of aromatic unsaturated components; d) subjecting the third intermediate to steam cracking conditions in a third reaction zone to produce a fourth intermediate; and e) Separate the fourth intermediate to produce a fifth intermediate comprising benzene, ethylene, propylene, or a combination thereof, and a second residual fraction.

7. The process of claim 6, further comprising recovering the ethylbenzene from the second intermediate product, and: a) Oxidize at least a portion of the ethylbenzene to form ethylbenzene hydroperoxide, catalytically react the ethylbenzene hydroperoxide with propylene to form propylene oxide and 1-phenylethanol, and dehydrate the 1-phenylethanol to produce styrene monomer; b) Dehydrogenating at least a portion of the ethylbenzene to produce styrene monomer; or c) Its combination.

8. The process according to claim 6 further includes: a) Recover the ethylene from the fifth intermediate product; as well as b) React the ethylene with benzene to form ethylbenzene.

9. The process according to claim 8, further comprising: a) Oxidize the ethylbenzene to form ethylbenzene hydroperoxide; b) Catalytically react the ethylbenzene hydroperoxide with propylene to form propylene oxide and 1-phenylethanol; as well as c) Dehydrate 1-phenylethanol to produce styrene monomer.

10. The process according to claim 6, further comprising: a) Recover the propylene from the fifth intermediate product; b) Catalytically react the propylene with ethylbenzene hydroperoxide to form propylene oxide and 1-phenylethanol; as well as c) Dehydrate 1-phenylethanol to produce styrene monomer.

11. The process according to claim 6, further comprising: a) Recover the benzene from the third intermediate or the fourth intermediate; as well as b) React the benzene with ethylene to form ethylbenzene.

12. The process according to claim 11, further comprising: a) Oxidize at least a portion of the ethylbenzene to form ethylbenzene hydroperoxide, catalytically react the ethylbenzene hydroperoxide with propylene to form propylene oxide and 1-phenylethanol, and dehydrate the 1-phenylethanol to produce styrene monomer; b) Dehydrogenating at least a portion of the ethylbenzene to produce styrene monomer; or c) Its combination.

13. The process according to claim 6, further comprising: a) At least a portion of the second residual fraction is added as additional feed to the third reaction zone; b) Send at least a portion of the first residual fraction outside the process for further processing; or c) Its combination.

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