Two-stage catalytic process for upgrading pyrolysis oil to btxes

Abstract

According to one or more embodiments of this disclosure, a multi-stage method for upgrading pyrolysis oil comprising polyaromatic compounds to benzene, toluene, ethylbenzene, and xylene (BTEX) includes: upgrading the pyrolysis oil in a slurry-phase reactor zone to produce an intermediate product, wherein the slurry-phase reactor zone includes a mixed metal oxide catalyst; and hydrocracking the intermediate product in a fixed-bed reactor zone to produce BTEX, wherein the fixed-bed reactor zone includes a mesoporous zeolite-supported metal catalyst.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Patent Application Serial No. 17 / 519,758, filed November 5, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The embodiments disclosed herein generally relate to petroleum products, and particularly to methods for upgrading pyrolysis oils. Background Technology

[0004] Pyrolysis oil, or pyrolysis fuel oil, is a heavy stream that exits typical crude oil hydrotreating processes as a bottom fraction of a steam cracker. This heavy stream is low in sulfur but rich in aromatic compounds. While these characteristics may make pyrolysis oil an ideal feedstock for subsequent chemical conversion, traditional upgrading methods for pyrolysis oil are complex and inefficient. Summary of the Invention

[0005] Pyrolysis oil is typically burned as fuel and is not considered to have high value. However, due to its high aromatic content, the relatively inexpensive pyrolysis oil becomes an ideal feedstock for the production of valuable intermediate petrochemical products such as benzene, toluene, ethylbenzene, and xylene (BTEX). The BTEX can then be processed to maximize the p-xylene content, a key component in the production of purified terephthalic acid (PTA) and final polyesters. Therefore, there is a continued need for novel, simplified, and more efficient methods for upgrading pyrolysis oil. Embodiments of this disclosure pertain to such methods.

[0006] According to one embodiment, a multi-stage method for upgrading pyrolysis oil comprising polyaromatic compounds to benzene, toluene, ethylbenzene, and xylene (BTEX) includes: upgrading the pyrolysis oil in a slurry-phase reactor zone to produce intermediate products, wherein the slurry-phase reactor zone includes a mixed metal oxide catalyst; and hydrocracking the intermediate products in a fixed-bed reactor zone to produce BTEX, wherein the fixed-bed reactor zone includes a mesoporous zeolite-supported metal catalyst.

[0007] Additional features and advantages of the embodiments described herein will be set forth in the detailed description below, and will be partly readily understood from the description or recognized by those skilled in the art through practice of the described embodiments (including the detailed description and claims provided below).

[0008] Brief description of the attached figures

[0009] The following detailed description of specific embodiments of this disclosure can be best understood when read in conjunction with the following accompanying drawings, in which:

[0010] Figure 1This is a diagram of a system for producing BTEX from pyrolysis oil feedstock, according to the embodiments disclosed herein;

[0011] Figure 2 This is a diagram illustrating the cascade reactions that can occur in the slurry phase reactor zone according to the embodiments described herein; and

[0012] Figure 3 This is a diagram of a cascade reaction that can occur in a fixed-bed reactor zone according to the implementation scheme described herein. Detailed Implementation

[0013] As used herein, the term "hydrocarbon oil" or "hydrocarbon feedstock" refers to an oily liquid consisting primarily of a mixture of hydrocarbon compounds. Hydrocarbon oil may include refined oils obtained from crude oil, synthetic crude oil, bitumen, oil sands, shale oil, or kerosene. The term "refined oil" includes, but is not limited to: vacuum gas oil (VGO), dearomatized oil (DAO) or demetallized oil (DMO) obtained by dearomatization processes, light and / or heavy coking gas oils obtained by coking processes, circulating oils obtained from FCC processes, and gas oils obtained from viscous cracking processes.

[0014] As used herein, the term "hydrocarbon" refers to a compound composed entirely of carbon and hydrogen atoms. Examples include "C..." x -C y The term "hydrocarbon" refers to hydrocarbons having x to y carbon atoms. For example, C1-C5 hydrocarbons include methane, ethane, propane, butane, and pentane.

[0015] As used herein, the term "polyaromatic compound" refers to a compound consisting of three or more aromatic rings. Polyaromatic compounds having fewer than seven aromatic rings are generally referred to as "polynuclear aromatic compounds" ("PNA"), and polyaromatic compounds having seven to ten aromatic rings are generally referred to as "heavy polynuclear aromatic compounds" ("HPNA").

[0016] As used herein, the terms "hydrogen / oil ratio" or "hydrogen to oil ratio" or "hydrogen to hydrocarbon ratio" refer to a standard measure of the ratio of the volume of hydrogen circulating through the reactor to the volume of feed. The hydrogen / oil ratio can be determined by comparing the flow rate volume of the hydrogen stream with the flow rate volume of the hydrocarbon feed.

[0017] As used herein, the term “liquid time space velocity” or “LHSV” refers to the ratio of the liquid flow rate of the hydrocarbon feed to the volume of the catalyst.

[0018] As used herein, the term "conduit" includes casing, lining, pipe, tube, coiled tubing, and mechanical structures with internal voids.

[0019] As used herein, the term “decreased content” of a substance means that the concentration of the substance is higher before passing through a stage of the process being examined than it is after passing through that stage. As used herein, the term “increased content” of a substance means that the concentration of the substance is higher after passing through a stage of the process being examined than it is before passing through that stage.

[0020] As used throughout this disclosure, "zeolite" can refer to a microporous inorganic material with regular intracrystalline cavities and channels at the molecular scale. Zeolites typically contain crystalline structures, as opposed to the amorphous structures that can be observed, for example, in some porous materials (e.g., amorphous silica). Zeolites typically comprise a microporous framework that can be identified by its framework type. The microporous structure of zeolites (e.g., pore sizes from 0.3 nm to 2 nm) can provide a large surface area and desirable size / shape selectivity, which can be beneficial for catalysis. The zeolite may comprise, for example, aluminosilicates, titanosilicates, or pure silicates. In embodiments, the zeolite may comprise micropores (present in the microstructure of the zeolite) and additionally mesopores. As used throughout this disclosure, a micropore is defined as a pore in a structure with a diameter greater than or equal to 0.1 nm and less than or equal to 2 nm, and a mesopore is defined as a pore in a structure with a diameter greater than 2 nm and less than or equal to 50 nm. Unless otherwise described herein, the term "pore size" for a material refers to the average pore size, but the material may also include micropores and / or mesopores with specific sizes different from the average pore size.

[0021] According to one aspect, a multi-stage method for upgrading pyrolysis oil comprising polyaromatic compounds to BTEX includes upgrading the pyrolysis oil in a slurry-phase reactor zone to produce an intermediate product and hydrocracking the intermediate product in a fixed-bed reactor zone. Although the method described herein is not limited to any particular apparatus, Figure 1 A schematic diagram of a system suitable for implementing the methods described herein is provided.

[0022] refer to Figure 1 The upgrading system 10 includes a first reactor 12 and a second reactor 14. In an embodiment, the first reactor 12 may be a slurry reactor and the second reactor 14 may be a fixed-bed reactor.

[0023] In operation, the pyrolysis oil feed can be added to the first reactor 12 via conduit 16. The first reactor 12 may include a mixed metal oxide catalyst, which is described in more detail below. The pyrolysis oil, optionally with a diluent, can be contacted with the mixed metal oxide catalyst while hydrogen is added to the first reactor 12. In an embodiment, the mixed metal oxide catalyst can be added simultaneously with the pyrolysis oil feed, such that the liquid and solid phases can be mixed to produce a slurry for a slurry reactor. After allowing the reaction to proceed, the entire slurry can be transferred via conduit 19 to a separator 18, which separates the gaseous products, liquid products, and used catalyst (solids). The gaseous products can be collected via vent 20, the liquid products can be conveyed via conduit 22 to the second reactor 14, and the solids can be conveyed via conduit 25 to a catalyst recovery unit 24. In the catalyst recovery unit 24, the catalyst is separated from residual polyaromatic compounds and other heavy residues. The catalyst can be collected via conduit 25, and the residues can be recycled back to the pyrolysis oil feed via conduit 27. The collected catalyst can be recovered and recycled back to the first reactor 12.

[0024] As described above, the second reactor 14 can be a fixed-bed reactor and can contain a mesoporous zeolite-supported metal catalyst, as described in more detail below. The liquid product from the first reactor 12 can be contacted with the mesoporous zeolite-supported metal catalyst while hydrogen is added to the second reactor 14. Optionally, before contacting with the mesoporous zeolite-supported metal catalyst, the liquid product from the separator 18 can pass through a heat exchanger 28 and then enter the second reactor 14 via a conduit 30, as... Figure 1 As shown. After the reaction is permitted, the resulting gaseous product can be separated from the liquid product in separator 32 and then discharged via conduit 34 or analyzed, for example, by gas chromatograph 36. The liquid product can be collected in collector 38. In an embodiment, the liquid product can be cooled by passing it through a heat exchanger (not shown) before being collected in collector 38. If necessary, various flow rate control devices, such as valves and pumps 40, can be used throughout the system.

[0025] An implementation scheme for a system for performing a multi-stage process for upgrading pyrolysis oil has been described, and an implementation scheme for that method will be described next.

[0026] In this embodiment, pyrolysis oil, a diluent, hydrogen, and a mixed metal oxide catalyst are added to the slurry phase reactor. In some embodiments, these components may be added simultaneously, or in other embodiments, they may be added at different times. The reactor may be agitated. In this embodiment, agitation may include stirring. In other embodiments, agitation may include shaking. In this embodiment, the reactor may be agitated by both stirring and shaking.

[0027] Pyrolysis oil and a mixed metal oxide catalyst are contacted in the slurry-phase reactor zone, where the cracking of polyaromatic compounds is induced through continuous selective hydrogenation, selective saturated ring opening, hydrodealkylation, alkyl transfer, and disproportionation, thereby producing diaromatic intermediates, which will be described in more detail below. Examples of these cascaded reactions are as follows: Figure 2 As shown, the reaction starts with pyrene and produces methylated naphthalene. Of course, the formation of methylated naphthalene from pyrene is just one example of a cascade reaction; other starting materials and products are also under consideration.

[0028] In the embodiments, the pyrolysis oil may include one or more polyaromatic compounds. The polyaromatic compounds may include 16 or more aromatic carbon atoms (C6A). 16 +), for example, C 16 -C 110 Polyaromatic compounds. For example, polyaromatic compounds can be C 16 -C 100 C 16 -C 90 C 16 -C 80 C 16 -C 70 C 16 -C 60 C 16 -C 50 C 16 -C 40 C 16 -C 30 C 16 -C 20 C 20 -C 110 C 30 -C 110 C 40 -C 110 C 50 -C 110 C 60 -C 110 C 70 -C 110 C 80 -C 110 C 90 -C 110 Or even C 100 -C 110 Polyaromatic compounds. In embodiments, polyaromatic compounds may include multiple fused aromatic rings, such as 3, 4, 5, 6, 7, 8, 9, or 10 fused benzene rings.

[0029] In the implementation scheme, the diluent may be an organic solvent, such as toluene, benzene, or a combination of toluene and benzene. Without wishing to be bound by any particular theory, it is believed that the diluent increases the flowability of the pyrolysis oil feed, allowing the original pyrolysis oil to contact the mixed metal oxide catalyst better than it might be without a diluent.

[0030] Reactor conditions, such as the inflow rate, temperature, and pressure, can be altered to control the reaction in the first reactor. In embodiments, the hydrogen flow rate can be from 15 ml / min to 35 ml / min, for example, 20 ml / min to 35 ml / min, 25 ml / min to 35 ml / min, 30 ml / min to 35 ml / min, 15 ml / min to 30 ml / min, 15 ml / min to 25 ml / min, or even 15 ml / min to 20 ml / min. It is contemplated that the hydrogen flow rate can range from any lower limit to any upper limit disclosed herein. Without wishing to be bound by any particular theory, it is believed that a hydrogen flow rate less than 15 ml / min entering the reactor may not allow sufficient levels of hydrogen to enter the reactor. However, a hydrogen flow rate greater than 35 ml / min may result in excessive hydrogen circulating within the system, thus consuming an unacceptable amount of hydrogen.

[0031] In the implementation scheme, the pyrolysis oil, diluent, hydrogen, and mixed metal oxide catalyst are allowed to reside in the slurry phase reactor for a period of 1.5 h to 7.5 h. For example, the components may be allowed to reside in the slurry phase reactor for 1.5 h to 7 h, 1.5 h to 6.5 h, 1.5 h to 6 h, 1.5 h to 5.5 h, 1.5 h to 5 h, 1.5 h to 4.5 h, 1.5 h to 4 h, 1.5 h to 3.5 h, 1.5 h to 3 h, 1.5 h to 2.5 h, 1.5 h to 2 h, 2 h to 7.5 h, 2.5 h to 7.5 h, 3 h to 7.5 h, 3.5 h to 7.5 h, 4 h to 7.5 h, 4.5 h to 7.5 h, 5 h to 7.5 h, 5.5 h to 7.5 h, 6 h to 7.5 h, 6.5 h to 7.5 h, or even 7 h to 7.5 h. It is conceivable that the flow rates of the pyrolysis oil and diluent can range from any lower limit to any upper limit disclosed herein. Without wishing to be bound by any particular theory, it is believed that if the components are allowed to remain in the slurry-phase reactor for less than 1.5 hours, one or more of the following processes—continuous selective hydrogenation, selective ring-opening, hydrodealkylation, alkyl transfer, and disproportionation—may not have sufficient time to complete. However, if this time is extended beyond 7.5 hours, unwanted byproducts may be generated.

[0032] In the implementation scheme, the first reactor in the slurry phase reactor zone can operate at a temperature of 350°C to 450°C, for example, 360°C to 450°C, 370°C to 450°C, 380°C to 450°C, 390°C to 450°C, 400°C to 450°C, 410°C to 450°C, 420°C to 450°C, 430°C to 450°C, 440°C to 450°C, 350°C to 440°C, 350°C to 430°C, 350°C to 420°C, 350°C to 410°C, 350°C to 400°C, 350°C to 390°C, 350°C to 380°C, 350°C to 370°C, or even 350°C to 360°C. The envisioned temperature can range from any lower limit to any upper limit disclosed herein. Not wanting to be bound by any particular theory, it is believed that reactor temperatures below 350°C would cause one or more of the following reactions—continuous selective hydrogenation, selective ring opening, hydrodealkylation, alkyl transfer, and disproportionation—to proceed too slowly to be commercially viable, while reactor temperatures above 450°C might cause one or more of these reactions to proceed too quickly, potentially leading to runaway reactions or premature catalyst deactivation.

[0033] In the implementation scheme, the first reactor in the slurry phase reactor zone can operate at the following pressures: 3 MPa to 18 MPa, 3.5 MPa to 18 MPa, 4 MPa to 18 MPa, 4.5 MPa to 18 MPa, 5 MPa to 18 MPa, 5.5 MPa to 18 MPa, 6 MPa to 18 MPa, 6.5 MPa to 18 MPa, 7 MPa to 18 MPa, 7.5 MPa to 18 MPa, 8 MPa to 18 MPa, 8.5 MPa... a to 18MPa, 9MPa to 18MPa, 9.5MPa to 18MPa, 10MPa to 18MPa, 10.5MPa to 18MPa, 11MPa to 18MPa, 11.5MPa to 18MPa, 12MPa to 18MPa, 12.5MPa to 18MPa, 13MPa to 18MPa, 13.5MPa to 18MPa, 14MPa to 18MPa, 14.5MPa to 18MPa, 15MPa to 18MPa, 15.5MPa to 18MPa, 16MPa to 18MPa, 3MPa to 17.5MPa, 3MPa to 17MPa, 3MPa to 16.5MPa, 3MPa to 16MPa, 3MPa to 15.5MPa, 3MPa to 15MPa, 3MPa to 14.5MPa, 3MPa to 14MPa, 3MPa to 13.5MPa, 3MPa to 13MPa, 3MPa to 12.5MPa, 3MPa Pressures can range from 12 MPa to 11.5 MPa, 3 MPa to 11 MPa, 3 MPa to 10.5 MPa, 3 MPa to 10 MPa, 3 MPa to 9.5 MPa, 3 MPa to 9 MPa, 3 MPa to 8.5 MPa, 3 MPa to 8 MPa, 3 MPa to 7.5 MPa, 3 MPa to 7 MPa, 3 MPa to 6.5 MPa, 3 MPa to 6 MPa, 3 MPa to 5.5 MPa, or even 3 MPa to 5 MPa. Pressures can be assumed to range from any lower limit to any upper limit disclosed herein. It is not intended to be bound by any particular theory, but pressures below 3 MPa are believed to be insufficient for one or more of the following: sequential selective hydrogenation, selective ring-opening, hydrodealkylation, alkyl transfer, and disproportionation. However, pressures above 18 MPa may require specialized high-pressure equipment, which would increase the cost of conducting the reaction.

[0034] The slurry-phase reactor includes a mixed metal oxide catalyst. In embodiments, the mixed metal oxide catalyst includes two or more of Fe₂O₃, ZrO₂, CeO₂, Al₂O₃, TiO₂, MoO₃, Co₂O₃, and NiO. In embodiments, the mixed metal oxide catalyst may include 70% to 90% by weight of Fe₂O₃; 5% to 60% by weight of ZrO₂; 1% to 4% by weight of CeO₂; and 5% to 10% by weight of Al₂O₃, wherein the weight percentages are based on the total amount of oxides. In embodiments, the mixed metal oxide catalyst may include 10% to 50% by weight of TiO₂; 10% to 15% by weight of MoO₃; 1% to 10% by weight of Co₂O₃; and 1% to 5% by weight of NiO, wherein the weight percentages are based on the total amount of oxides.

[0035] After the pyrolysis oil is contacted with the mixed metal oxide catalyst, a gaseous, liquid, and solid phases are generated, which can be separated from each other. The gaseous phase can be vented or collected. Conveniently, the gaseous phase can be analyzed before collection or venting, allowing for the calculation of the mass balance before and after the reaction. The solid phase comprises the used mixed metal oxide catalyst, which can be recycled to the slurry phase reactor. The liquid phase comprises intermediates, which are sent to the fixed-bed reactor zone for further processing. In embodiments, the intermediates may include diaromatic compounds and monoaromatic compounds. Examples of diaromatic compounds include, but are not limited to, naphthalene and 1,2,3,4-tetrahydronaphthalene, both of which may be unsubstituted or substituted with straight-chain or branched hydrocarbon substituents. Examples of monoaromatic compounds include, but are not limited to, benzene, which may be unsubstituted or substituted with straight-chain or branched hydrocarbon substituents.

[0036] In the implementation scheme, 90% to 100% of the pyrolysis oil can be converted into intermediate products. For example, 90% to 99%, 90% to 98%, 90% to 97%, 90% to 96%, 90% to 95%, 90% to 94%, 90% to 93%, 90% to 92%, 90% to 91%, 91% to 100%, 92% to 100%, 93% to 100%, 94% to 100%, 95% to 100%, 96% to 100%, 97% to 100%, 98% to 100%, or even 99% to 100% of the pyrolysis oil can be converted into intermediate products. The yield of the intermediate products is envisioned to range from any lower limit to any upper limit disclosed herein.

[0037] The liquid phase can be fed to a second reactor within the fixed-bed reactor zone. In an embodiment, an optional heat exchanger can be located between the slurry reactor zone and the fixed-bed reactor zone, allowing the temperature of the liquid phase to be controlled prior to its introduction into the fixed-bed reactor. The optional heat exchanger can help maintain the temperature of the liquid intermediate product at a level sufficient to prevent condensation of the intermediate product between the slurry reactor and the fixed-bed reactor.

[0038] Intermediates from the slurry-phase reactor zone are contacted with a mesoporous zeolite-supported metal catalyst (described more fully below) to produce BTEX via selective hydrogenation, selective ring-opening, followed by further hydrogenation-dealkylation, alkyl transfer, and disproportionation. This cascade reaction is as follows: Figure 3 As shown, BTEX is produced starting from naphthalene. Excessive cracking may also produce saturated hydrocarbons. Of course, the formation of BTEX from naphthalene is just one example of a cascade reaction, and other starting materials are being considered.

[0039] Reactor conditions, such as the inflow rate, temperature, and pressure, can be altered to control the reaction in the second reactor. In embodiments, the hydrogen flow rate can be from 15 ml / min to 35 ml / min, for example, 20 ml / min to 35 ml / min, 25 ml / min to 35 ml / min, 30 ml / min to 35 ml / min, 15 ml / min to 30 ml / min, 15 ml / min to 25 ml / min, or even 15 ml / min to 20 ml / min. It is contemplated that the hydrogen flow rate can range from any lower limit to any upper limit disclosed herein. Without wishing to be bound by any particular theory, it is believed that a hydrogen flow rate less than 15 ml / min entering the reactor may not allow sufficient levels of hydrogen to enter the reactor. However, a hydrogen flow rate greater than 35 ml / min may result in excessive hydrogen circulating within the system, thus consuming an unacceptable amount of hydrogen.

[0040] In the embodiments, the flow rate of the liquid product stream from the slurry phase reactor zone can be from 0.2 g / min to 1 g / min, for example 0.3 g / min to 1 g / min, 0.4 g / min to 1 g / min, 0.5 g / min to 1 g / min, 0.6 g / min to 1 g / min, 0.7 g / min to 1 g / min, 0.8 g / min to 1 g / min, 0.9 g / min to 1 g / min, 0.2 g / min to 0.9 g / min, 0.2 g / min to 0.8 g / min, 0.2 g / min to 0.7 g / min, 0.2 g / min to 0.6 g / min, 0.2 g / min to 0.5 g / min, 0.2 g / min to 0.4 g / min, or even 0.2 g / min to 0.3 g / min. It is contemplated that the flow rate of the liquid product stream from the slurry phase reactor zone can range from any lower limit disclosed herein to any upper limit disclosed herein. Any convenient device for controlling the flow rate can be used, such as a liquid pump. Without being bound by any particular theory, it is believed that a flow rate of less than 0.2 g / min from the liquid product stream in the slurry reactor zone may not allow a sufficient level of liquid product stream to enter the reactor. However, a flow rate greater than 1 g / min may cause excessive liquid product stream to circulate within the system, resulting in an unacceptable amount of liquid product stream remaining unreacted upon exiting the reactor.

[0041] In the implementation, the second reactor in the fixed-bed reactor zone can operate at temperatures from 350°C to 450°C, for example, 360°C to 450°C, 370°C to 450°C, 380°C to 450°C, 390°C to 450°C, 400°C to 450°C, 410°C to 450°C, 420°C to 450°C, 430°C to 450°C, 440°C to 450°C, 350°C to 440°C, 350°C to 430°C, 350°C to 420°C, 350°C to 410°C, 350°C to 400°C, 350°C to 390°C, 350°C to 380°C, 350°C to 370°C, or even 350°C to 360°C. The envisioned temperature can range from any lower limit to any upper limit disclosed herein. The temperature within the fixed-bed reactor can, but does not need to, be the same as the temperature within the slurry phase reactor. Not wanting to be bound by any particular theory, it is believed that reactor temperatures below 350°C would cause one or more of selective hydrogenation, selective saturated ring opening and then further hydrogenation-dealkylation, alkyl transfer and disproportionation to proceed too slowly to be commercially viable, but reactor temperatures above 450°C would cause one or more of these reactions to proceed too quickly, which could lead to runaway reactions or premature catalyst deactivation.

[0042] In the implementation scheme, the second reactor in the fixed-bed reactor zone can operate at the following pressures: 3 MPa to 18 MPa, 3.5 MPa to 18 MPa, 4 MPa to 18 MPa, 4.5 MPa to 18 MPa, 5 MPa to 18 MPa, 5.5 MPa to 18 MPa, 6 MPa to 18 MPa, 6.5 MPa to 18 MPa, 7 MPa to 18 MPa, 7.5 MPa to 18 MPa, 8 MPa to 18 MPa, 8.5 MPa... a to 18MPa, 9MPa to 18MPa, 9.5MPa to 18MPa, 10MPa to 18MPa, 10.5MPa to 18MPa, 11MPa to 18MPa, 11.5MPa to 18MPa, 12MPa to 18MPa, 12.5MPa to 18MPa, 13MPa to 18MPa, 13.5MPa to 18MPa, 14MPa to 18MPa, 14.5MPa to 18MPa, 15MPa to 18MPa, 15.5MPa to 18MPa, 16MPa to 18MPa, 3MPa to 17.5MPa, 3MPa to 17MPa, 3MPa to 16.5MPa, 3MPa to 16MPa, 3MPa to 15.5MPa, 3MPa to 15MPa, 3MPa to 14.5MPa, 3MPa to 14MPa, 3MPa to 13.5MPa, 3MPa to 13MPa, 3MPa to 12.5MPa, 3MPa Pressures can range from 12 MPa to 11.5 MPa, 3 MPa to 11 MPa, 3 MPa to 10.5 MPa, 3 MPa to 10 MPa, 3 MPa to 9.5 MPa, 3 MPa to 9 MPa, 3 MPa to 8.5 MPa, 3 MPa to 8 MPa, 3 MPa to 7.5 MPa, 3 MPa to 7 MPa, 3 MPa to 6.5 MPa, 3 MPa to 6 MPa, 3 MPa to 5.5 MPa, or even 3 MPa to 5 MPa. Pressures can be assumed to range from any lower limit to any upper limit disclosed herein. Pressures within a fixed-bed reactor can, but do not need to, be the same as those within a slurry-phase reactor. It is not desired to be bound by any particular theory, but pressures below 3 MPa are believed to be insufficient for selective hydrogenation, selective ring-opening, and subsequently further hydrodealkylation, alkyl transfer, and disproportionation. However, pressures above 18 MPa may require specialized high-pressure equipment, which would increase the cost of conducting the reaction.

[0043] Fixed-bed reactors comprise metal catalysts supported on mesoporous zeolites. Generally, zeolites can be characterized by the framework type defining their microporous structure. In one or more embodiments, the zeolites described herein are not particularly limited to a specific framework type. Framework types are described, for example, in "Atlas of Zeolite Framework Types" (Fifth Revision, 2001) by Ch. Baerlocher et al., which is incorporated herein by reference. In embodiments, the zeolite may comprise a microstructure (including micropores) characterized, among others, as a *BEA framework zeolite (e.g., but not limited to β-zeolite), a FAU framework zeolite (e.g., but not limited to Y-zeolite), a MOR framework zeolite, or an MFI framework zeolite (e.g., but not limited to ZSM-5). It should be understood that *BEA, MFI, MOR, and FAU refer to zeolite framework types identified by their respective three-letter codes established by the International Zeolite Association (IZA). Other framework types are also under consideration in the currently disclosed embodiments. In the embodiments, the mesoporous zeolite of the catalyst can be β-zeolite, ZSM-5, mordenite, Y-zeolite, or a combination of two or more thereof. The metal of the catalyst can be derived from a heteropolyacid. Exemplary heteropolyacids include Keggin-type heteropolyacids, such as phosphotungstic acid (H3PW). 12 O 40 ), phosphomolybdic acid (H3PMo) 12 O 40 ), silicotungsten heteropolyacid (H4SiW) 12 O 40 ), silicomolybdenum heteropolyacid (H4SiMo) 12 O 40 One or more of the following.

[0044] After the liquid-phase intermediates contact with the mesoporous zeolite-supported metal catalyst in the fixed-bed reactor zone, gas and liquid phases are produced. A liquid / gas separator can be used to separate the gas and liquid phases from each other. The gas phase can be vented or collected. Conveniently, the gas phase can be analyzed before collection or venting, allowing for the calculation of mass balances before and after the reaction. The liquid phase, including BTEX, can be cooled using, for example, a heat exchanger before collection.

[0045] In the implementation plan, 50% to 75% of the pyrolysis oil can be converted into BTEX (“total yield”). For example, the total yield can be 51% to 75%, 52% to 75%, 53% to 75%, 54% to 75%, 55% to 75%, 56% to 75%, 57% to 75%, 58% to 75%, 59% to 75%, 60% to 75%, 61% to 75%, 62% to 75%, 63% to 75%, 64% to 75%, 65% to 75%, 66% to 75%, 67% to 75%, 68% to 75%, 69% to 75%, 70% to 75%, etc. 5%, 50% to 74%, 50% to 73%, 50% to 72%, 50% to 71%, 50% to 70%, 50% to 69%, 50% to 68%, 50% to 67%, 50% to 66%, 50% to 65%, 50% to 64%, 50% to 63%, 50% to 62%, 50% to 61%, 50% to 60%, 50% to 59%, 50% to 58%, 50% to 57%, 50% to 56%, or even 50% to 55%. The total yield can be envisioned to range from any lower limit disclosed herein to any upper limit disclosed herein.

[0046] The embodiments described herein can help limit the content of aromatic compounds in fuels, thereby contributing to environmental protection. Furthermore, these embodiments ensure the production of aromatic compounds under relatively mild conditions, which are valuable industrially as intermediates. For example, pyrolysis oil can now be used as a feedstock for the production of para-xylene, a well-known intermediate in the production of PTA.

[0047] According to the first aspect, alone or in combination with any other aspect, a multi-stage method for upgrading pyrolysis oil comprising polyaromatic compounds to benzene, toluene, ethylbenzene, and xylene (BTEX) comprises: upgrading the pyrolysis oil in a slurry-phase reactor zone to produce an intermediate product, wherein the slurry-phase reactor zone comprises a mixed metal oxide catalyst; and hydrocracking the intermediate product in a fixed-bed reactor zone to produce BTEX, wherein the fixed-bed reactor zone comprises a mesoporous zeolite-supported metal catalyst.

[0048] According to the second aspect, alone or in combination with any other aspect, the slurry phase reactor zone operates at a temperature of 350°C to 450°C.

[0049] According to the third aspect, alone or in combination with any other aspect, the slurry phase reactor zone operates at a pressure of 3 MPa to 18 MPa.

[0050] According to the fourth aspect, alone or in combination with any other aspect, the mixed metal oxide catalyst comprises two or more of Fe2O3, ZrO2, CeO2, Al2O3, TiO2, MoO3, Co2O3, and NiO.

[0051] According to the fifth aspect, alone or in combination with any other aspect, the mixed metal oxide catalyst comprises: 70% to 90% by weight of Fe2O3; 5% to 60% by weight of ZrO2; 1% to 4% by weight of CeO2; and 5% to 10% by weight of Al2O3, wherein the weight percentages are calculated based on the total amount of oxides.

[0052] According to the sixth aspect, alone or in combination with any other aspect, the mixed metal oxide catalyst comprises: 10 wt% to 50 wt% TiO2; 10 wt% to 15 wt% MoO3; 1 wt% to 10 wt% Co2O3; and 1 wt% to 5 wt% NiO, wherein the wt% is calculated based on the total amount of oxides.

[0053] According to the seventh aspect, alone or in combination with any other aspect, the fixed-bed reactor zone operates at a temperature of 350°C to 450°C.

[0054] According to the eighth aspect, alone or in combination with any other aspect, the fixed-bed reactor zone operates at pressures from 3 MPa to 18 MPa.

[0055] According to the ninth aspect, alone or in combination with any other aspect, the metal of the mesoporous zeolite-supported metal catalyst includes heteropolyacids.

[0056] According to aspect ten, alone or in combination with any other aspect, the heteropolyacid includes those selected from phosphotungstic heteropolyacids (H3PW). 12 O 40 ), phosphomolybdic acid (H3PMo) 12 O 40 ), silicotungsten heteropolyacid (H4SiW) 12 O 40 ), silicomolybdenum heteropolyacid (H4SiMo) 12 O 40 At least one Keggin-type heteropolyacid and combinations thereof.

[0057] According to the eleventh aspect, alone or in combination with any other aspect, the zeolite carrier comprises zeolite selected from β-zeolite, ZSM-5, mordenite, Y-zeolite, and combinations of two or more thereof.

[0058] According to aspect 12, alone or in combination with any other aspect, the polyaromatic compound includes C 16 And larger polyaromatic compounds.

[0059] According to aspect thirteen, alone or in combination with any other aspect, greater than or equal to 95% of the stated C 16Larger polyaromatic compounds are converted to BTEX in the multi-stage process.

[0060] According to aspect fourteen, alone or in combination with any other aspect, the BTEX yield from the polyaromatic compound is 50% to 70% in percentage of the amount of the polyaromatic compound.

[0061] According to aspect fifteen, alone or in combination with any other aspect, the intermediate product is selected from naphthalene, 1,2,3,4-tetrahydronaphthalene, benzene substituted with straight-chain or branched hydrocarbon substituents, and combinations of two or more thereof.

[0062] Example

[0063] Using the above-described implementation method, an exemplary scheme for producing BTEX was executed.

[0064] Synthesis of mixed metal oxide catalysts

[0065] An exemplary mixed metal oxide catalyst was formulated with the following composition: 83 wt% Fe₂O₃, 7.5 wt% ZrO₂, 2.5 wt% CeO₂, and 7 wt% Al₂O₃, concentrations calculated on an oxide basis. Fe(NO₃)₃·9H₂O (40 g) was dissolved in 800 ml of distilled water to form solution A. Al(NO₃)₃·9H₂O (4.906 g), ZrO(NO₃)₂ (1.549 g), and Ce(NO₃)₃·6H₂O (0.601 g) were added to solution A to produce solution B, which was stirred for 30 minutes. Ammonium hydroxide solution (40 ml, 28%–30% NH₃ standard) was mixed with 60 ml of distilled water to produce solution C. Solution B was titrated to pH 7 by gradually adding solution C. The appropriately titrated solutions were mixed and allowed to precipitate for one hour. The precipitate was separated and dried overnight in a drying oven. The dried solid was then calcined in air at 500°C for two hours. The calcined product was then pulverized to obtain the final powdered mixed metal oxide catalyst.

[0066] Synthesis of metal catalysts supported on mesoporous zeolites

[0067] Preparation of graded Beta-M(50) zeolites

[0068] 22.2 g (HSZ-931HOA, Tosoh Corp.) of micron-sized β-zeolite with a SiO2 / Al2O3 ratio of 28 was added to 600 mL of 0.2 M NaOH solution. The mixture was subjected to hydrothermal desilication at 150 °C for 21 h. The resulting graded β-zeolite had a SiO2 / Al2O3 ratio of 20 and an average mesopore size of approximately 10 nm. The peak mesopore size ranged from 20 nm to 25 nm. The mesopore size distribution was obtained using the Barrett-Joyner-Halenda (BJH) model applied to the isothermal adsorption branch. The total pore volume was 0.59 cc / g. The micropore volume and total pore volume were estimated using nonlocal density functional theory (NLDFT).

[0069] A portion of the synthesized hierarchical β-zeolite was subjected to ion exchange in 0.8 M NH4NO3 at 80 °C for 2 hours, repeated three times. For example, 1 g of zeolite was ion-exchanged in 10 ml of NH4NO3 solution. The ion-exchanged zeolite was dried at 110 °C and calcined at 550 °C with a heating rate of 5 °C / min for 5 hours. The calcined zeolite was H-type mesoporous β-zeolite.

[0070] The acidity of mesoporous β-zeolite can be controlled by dealumination in dilute nitric acid solution. In these examples, all dealumination was performed by a single treatment in 0.2 M nitric acid solution at 80 °C for 2 hours. The dealugenized samples were then subjected to ion exchange in 0.8 M NH4NO3 at 80 °C for 2 hours, followed by drying and calcination at 550 °C for 5 hours. The dealugenized mesoporous β-zeolite (H type) is referred to as “Beta-M(50)” in the remaining examples.

[0071] Synthesis of CoMoP / Beta-M(50) catalyst

[0072] H3PMo 12 O 40 (1.44 g) was dissolved in 15 ml of distilled water to form solution A. Co(NO3)2·6H2O was dissolved in 15 ml of distilled water to form solution B. Solutions A and B were mixed together and added to Beta-M(50)(5 g) in a round-bottom flask. The resulting mixture was stirred for 2 hours. After stirring, the mixture was subjected to vacuum at 50 °C. The solid was dried at 100 °C overnight. The dried solid was calcined at 500 °C for 5 hours to provide the CoMoP / Beta-M(50) catalyst.

[0073] The CoMoP / Beta-M(50) catalyst was pretreated before being used in this method. For pretreatment, the catalyst was added to a fixed-bed reactor and then heated to 400°C at a hydrogen flow rate of 25 ml / min and atmospheric pressure at a heating rate of 5°C / min. Once the reactor temperature reached 400°C, the reactor was pressurized to 3 MPa with hydrogen, and then the hydrogen flow rate was maintained at 25 ml / min.

[0074] Obtaining BTEX from pyrolysis oil

[0075] The original pyrolysis oil (16.74 g) was mixed with toluene (4.37 g) to form a pyrolysis oil feed. The pyrolysis oil feed prepared above and the mixed metal oxide catalyst (12.17 g) were added to a slurry reactor. The mixture was stirred at 400 °C and 14 MPa for 4 hours. After the reaction, the mixture was sent to a separator to separate the gaseous products, liquid products, and solid used mixed metal oxide catalyst. The used mixed metal oxide catalyst was washed with toluene to remove any possible condensates and dried under vacuum at 20 °C to 100 °C.

[0076] The liquid product was fed at a feed rate of 0.6 g / h into a fixed-bed reactor containing 0.5 g of pretreated CoMoP / Beta-M(50) catalyst. The reactor temperature was maintained at 400 °C and 3 MPa. The hydrogen flow rate was maintained at 25 ml / min, and the reaction was allowed to proceed for 24 hours.

[0077] After passing through both a slurry-phase reactor and a fixed-bed reactor, 61.2% of the pyrolysis oil was converted to BTEX. The total yields of various products are provided in Table 1.

[0078]

[0079] Note that the descriptions in this disclosure of a component as being "operable" or "sufficient" in a particular manner to embody a particular property or function in a particular way are structural descriptions, contrary to descriptions intended for use. More specifically, references in this disclosure to a manner in which a component is "operable" or "sufficient" indicate the existing physical state of the component and are therefore considered explicit descriptions of the component's structural characteristics.

[0080] The singular forms “a,” “an,” and “the” include plural indicators unless the context clearly indicates otherwise.

[0081] A range is provided throughout this disclosure. Each discrete value contained within the range is also envisioned. Furthermore, a range that can be formed from each discrete value contained within the explicitly disclosed range is also envisioned.

[0082] As used in this disclosure and the appended claims, the words “comprising,” “having,” and “including,” and all their grammatical variations, are intended to have an open, non-limiting meaning that does not exclude additional elements or steps.

[0083] As used in this disclosure, terms such as “first” and “second” are arbitrarily designated and intended only to distinguish two or more instances or components. It should be understood that the terms “first” and “second” are not used for any other purpose and are not part of the name or description of a component, nor do they necessarily define the relative position, location, or order of the components. Furthermore, it should be understood that the mere use of the terms “first” and “second” does not require the existence of any “third” component, although such a possibility is also considered within the scope of this disclosure.

[0084] Having described the subject matter of this disclosure in detail and with reference to specific embodiments, it should be noted that the various details disclosed herein should not be construed as implying any connection to the elements that form the basic components of the various embodiments described herein. Furthermore, it will be apparent that modifications and changes can be made without departing from the scope of this disclosure (including, but not limited to, embodiments as defined in the appended claims).

Claims

1. A multi-stage method for upgrading pyrolysis oil containing polyaromatic compounds to benzene, toluene, ethylbenzene, and xylene (BTEX), said method comprising: The pyrolysis oil is upgraded in a slurry-phase reactor zone to produce an intermediate product, wherein the slurry-phase reactor zone includes a mixed metal oxide catalyst, wherein the mixed metal oxide catalyst comprises: 70% to 90% by weight of Fe2O3; 5% to 60% by weight of ZrO2; 1% to 4% by weight of CeO2; and 5% to 10% by weight of Al₂O₃, wherein the weight percentage is calculated based on a total amount of 100% by weight for the mixed metal oxide catalyst; and The intermediate product is hydrocracking in a fixed-bed reactor zone to produce BTEX, wherein the fixed-bed reactor zone comprises a mesoporous zeolite-supported metal catalyst, wherein the mesoporous zeolite-supported metal catalyst comprises a mesoporous zeolite support and at least one metal, wherein the mesoporous zeolite support comprises mesoporous β-zeolite, and The polyaromatic compounds mentioned above refer to compounds composed of three or more aromatic rings.

2. The multi-stage method according to claim 1, wherein the slurry phase reactor zone is operated at a temperature of 350°C to 450°C.

3. The multi-stage method according to claim 1 or 2, wherein the slurry phase reactor zone operates at a pressure of 3 MPa to 18 MPa.

4. The multi-stage method according to claim 1 or 2, wherein the fixed-bed reactor zone is operated at a temperature of 350°C to 450°C.

5. The multi-stage method according to claim 1 or 2, wherein the fixed-bed reactor zone operates at a pressure of 3 MPa to 18 MPa.

6. The multistage process of claim 1 or 2, wherein the polyaromatic compounds include C 16 and larger polyaromatic compounds.

7. The multistage process of claim 6, wherein greater than or equal to 95 wt% of the C 16 and larger polyaromatic compounds are converted to BTEX in the multistage process.

8. The multi-stage method according to claim 1 or 2, wherein the BTEX yield from the polyaromatic compound is 50% to 70% by weight, based on the weight percentage of the polyaromatic compound.

9. The multi-stage method according to claim 1 or 2, wherein the intermediate product is selected from naphthalene, 1,2,3,4-tetrahydronaphthalene, benzene substituted with straight-chain or branched hydrocarbon substituents, and combinations of two or more thereof.

10. The multi-stage method according to claim 1 or 2, wherein the mixed metal oxide catalyst is composed of Fe2O3, ZrO2, CeO2 and Al2O3.

11. The multi-stage method according to claim 1 or 2, wherein the mesoporous zeolite-supported metal catalyst is composed of cobalt, molybdenum, phosphorus, aluminum, silicon, oxygen atoms, and optionally hydrogen atoms.

12. The multi-stage method according to claim 1 or 2, wherein the intermediate product enters directly from the slurry phase reactor zone into the fixed bed reactor zone.

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