System and method for upgrading pyrolysis oil to light aromatics over mixed metal oxide catalysts

Abstract

A system for upgrading pyrolysis oil may include a pyrolysis upgrading unit having a mixed metal oxide catalyst and a separation unit operable to separate the spent mixed metal oxide catalyst from the reaction effluent. The method for upgrading pyrolysis oil may include contacting the pyrolysis oil with hydrogen under reaction conditions in the presence of the mixed metal oxide catalyst to produce a reaction effluent. The pyrolysis oil may include polycyclic aromatic compounds. The mixed metal oxide catalyst may include a plurality of catalyst particles, and each of the plurality of catalyst particles has a plurality of metal oxides. Contacting the pyrolysis oil with hydrogen under reaction conditions in the presence of the mixed metal oxide catalyst may convert at least a portion of the polycyclic aromatic compounds in the pyrolysis oil into light aromatic compounds.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. patent application serial number 17 / 167,489, filed on February 4, 2021, entitled “SYSTEM AND METHOD FOR UPGRADING PYROLYSIS OIL TO LIGHT AROMATIC HYDROCARBONS OVER A MIXED METAL OXIDE CATALYST,” which is incorporated by reference into this disclosure in its entirety. Technical Field

[0003] The present disclosure relates generally to systems and methods for upgrading hydrocarbons, and more particularly to systems and methods for upgrading pyrolysis oil to light aromatic compounds over a mixed metal oxide catalyst. Background Art

[0004] Crude oil can be converted into valuable chemical intermediates and products through one or more hydroprocessing processes. Hydroprocessing processes can include steam cracking, in which larger hydrocarbons in crude oil are cracked to form smaller hydrocarbons. The steam cracking unit produces an underflow, called pyrolysis oil. Pyrolysis oil can include an increased concentration of aromatic compounds compared to the crude oil feedstock. In many crude oil processing facilities, this pyrolysis oil is burned as a fuel. However, the aromatic compounds in the pyrolysis oil can be converted into more valuable chemical products and intermediates, which can be used as base materials in chemical synthesis processes. For example, aromatic compounds from pyrolysis oil can be converted into xylene, which can be the initial base material for the production of terephthalic acid, which can then be used to produce polyester. The aromatic compounds in pyrolysis oil can be upgraded to many other higher-value aromatic products and intermediates. The market demand for these higher-value aromatic compounds continues to grow. Summary of the invention

[0005] The pyrolysis oil in the steam cracking process can be upgraded by contacting the pyrolysis oil with a catalyst to produce higher value products and intermediates, and the catalyst can be operated to convert the polycyclic aromatic compounds in the pyrolysis oil into one or more light aromatic compounds, and the light aromatic compounds can include benzene, toluene, ethylbenzene, xylene, other aromatic compounds or a combination of these compounds. Existing catalysts that can be operated to upgrade the pyrolysis oil can include a multimetallic hydrocracking catalyst with two or more metals supported on a catalyst support. These multimetallic hydrocracking catalysts are usually prepared from traditional metal precursors, such as metal acid hydrates, metal nitrates, and other traditional metal precursors impregnated on a microporous catalyst support.

[0006] These conventional multi-metallic hydrocracking catalysts can be prepared using zeolite supports, which can be microporous, typically with an average pore size of less than about 2 nanometers (nm). However, the molecular size of polycyclic aromatic compounds present in pyrolysis oil can be larger than the average pore size of the zeolite supports used to prepare these conventional multi-metallic catalysts. Therefore, the small average pore size of the nanoporous zeolite can limit the access of larger polycyclic aromatic compounds to the reaction sites within the pores of the zeolite support, thereby reducing the yield and conversion rate achievable with these existing multi-metallic hydrocracking catalysts.

[0007] Therefore, there is a continuing need for improved catalysts for upgrading pyrolysis oil to produce light aromatic compounds. The present disclosure relates to a system for upgrading pyrolysis oil, which includes a mixed metal oxide catalyst. The present disclosure also relates to a method for modifying pyrolysis oil using a mixed metal oxide catalyst. The mixed metal oxide catalyst of the present disclosure may include a plurality of catalyst particles, and each of the plurality of catalyst particles may include a plurality of metal oxides. The mixed metal oxide catalyst of the present disclosure can convert a portion of polycyclic aromatic compounds in the pyrolysis oil into light aromatic compounds in a single step without performing a subsequent chemical reaction step. The system and method can also produce a higher yield of light aromatic compounds from the upgraded pyrolysis oil compared to upgrading the pyrolysis oil using existing multi-metal hydrocracking catalysts.

[0008] According to one or more aspects of the present disclosure, a method for upgrading pyrolysis oil may include contacting the pyrolysis oil with hydrogen under reaction conditions in the presence of a mixed metal oxide catalyst to produce a reaction effluent comprising light aromatic compounds. The pyrolysis oil may include polycyclic aromatic compounds. The mixed metal oxide catalyst may include a plurality of catalyst particles, and each of the plurality of catalyst particles may include a plurality of metal oxides. Contacting the pyrolysis oil with hydrogen under reaction conditions in the presence of a mixed metal oxide catalyst may convert at least a portion of the polycyclic aromatic compounds in the pyrolysis oil into light aromatic compounds.

[0009] According to one or more other aspects of the present disclosure, a system for upgrading pyrolysis oil may include a pyrolysis upgrading unit and a separation unit. The pyrolysis upgrading unit may include a mixed metal oxide catalyst. The mixed metal oxide catalyst may include a plurality of catalyst particles, and each of the plurality of catalyst particles may include a plurality of metal oxides. The pyrolysis upgrading unit is operable to contact the pyrolysis oil with hydrogen in the presence of the mixed metal oxide catalyst to produce a reaction effluent. The separation unit may be disposed downstream of the pyrolysis upgrading unit and may be operable to separate the spent mixed metal oxide catalyst from the reaction effluent to produce a reaction product including light aromatic compounds.

[0010] Other features and advantages of the techniques described in the present disclosure will be set forth in the detailed description that follows, and in part will be apparent to those skilled in the art from the description or learned by practicing the techniques described in the present disclosure (including the detailed description that follows, the claims, and the accompanying drawings).

[0011] BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The following detailed description of specific embodiments of the present disclosure may be best understood when read in conjunction with the following drawings, in which like structures are represented by like reference numerals, and in which:

[0013] Figure 1 schematically depicts a general flow diagram of a system for upgrading pyrolysis oil according to one or more embodiments shown and described in the present disclosure;

[0014] Figure 2 graphically illustrates the weight percentage (y-axis) of various components (x-axis) present in pyrolysis oil produced by steam cracking according to one or more embodiments shown and described in the present disclosure; and

[0015] Figure 3 A general flow diagram of another system for upgrading pyrolysis oil, including washing a spent mixed metal oxide catalyst, is schematically shown according to one or more embodiments shown and described in the present disclosure.

[0016] To describe Figure 1 and Figure 3 The simplified schematic diagram and description do not include many valves, temperature sensors, electronic controllers, etc. that can be used and are familiar to ordinary technicians in certain chemical processing operations. In addition, accompanying components that are typically included in chemical processing operations, such as, for example, air supply devices, heat exchangers, surge tanks, catalyst hoppers, or other related systems are not depicted. It should be understood that these components are within the spirit and scope of the disclosed embodiments of the present application. However, operating components such as those described in the present disclosure can be added to the embodiments described in the present disclosure.

[0017] It should also be noted that the arrows in the accompanying drawings refer to process streams. However, arrows can equally refer to transmission lines that can be used to transmit process steam between two or more system components. In addition, the arrows connected to the system components define the inlet or outlet in each given system component. The arrow direction generally corresponds to the main direction of movement of the material of the flow contained in the physical transmission line represented by the arrow. In addition, arrows that do not connect two or more system components represent product flows leaving the depicted system or entering the system inlet flow of the depicted system. The product flow can be further processed in the accompanying chemical treatment system, or it can be commercialized as a final product. The system inlet flow can be a flow transmitted from the accompanying chemical treatment system, or it can be an untreated raw material flow. Some arrows can represent a recycle flow, which is an effluent flow of the system component that is recycled back to the system. However, it should be understood that in some embodiments, any recycle flow represented can be replaced by a system inlet flow of the same material, and a portion of the recycle flow can leave the system as a system product.

[0018] In addition, arrows in the figures may schematically depict process steps that transfer streams from one system component to another system component. For example, an arrow pointing from one system component to another system component may represent the "transfer" of a system component effluent to another system component, which may include the contents of a process stream "leaving" or "removing" from one system component, and the "introduction" of the contents of a product stream to another system component.

[0019] It should be understood that when two or more lines are Figure 1 and Figure 3 When two or more process streams intersect in a schematic flow diagram of , two or more process streams are "mixed" or "combined". Mixing or combining can also include mixing by introducing the two streams directly into a similar reactor, separation device, or other system component. For example, it should be understood that when two streams are described as being combined directly before entering a separation unit or reactor, in some embodiments, the streams can equivalently be introduced into the separation unit or reactor and mixed in the reactor.

[0020] Reference will now be made in more detail to various embodiments of the present disclosure, some of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. DETAILED DESCRIPTION

[0021] Embodiments of the present disclosure relate to systems and methods for upgrading pyrolysis oil. Figure 1, schematically depicts one embodiment of a system 100 for upgrading a pyrolysis oil 102 of the present disclosure. The system 100 for upgrading a pyrolysis oil 102 may include a pyrolysis upgrading unit 110 and a separation unit 120 disposed downstream of the pyrolysis upgrading unit 110. The pyrolysis upgrading unit 110 may include a mixed metal oxide catalyst 106, which includes a plurality of catalyst particles, and each of the plurality of catalyst particles includes a plurality of metal oxides. The pyrolysis upgrading unit 110 is operable to contact the pyrolysis oil 102 with hydrogen 104 in the presence of the mixed metal oxide catalyst 106 to produce a reaction effluent 114. The separation unit 120 disposed downstream of the pyrolysis upgrading unit 110 is operable to separate a spent mixed metal oxide catalyst 124 from the reaction effluent 114 to produce a reaction product effluent 122 comprising light aromatic compounds. The present disclosure also relates to a method for upgrading a pyrolysis oil 102. In particular, the method may include contacting pyrolysis oil 102 with hydrogen 104 under reactive conditions in the presence of a mixed metal oxide catalyst 106 to produce a reaction effluent 114 comprising light aromatic compounds.

[0022] The various systems and methods for upgrading pyrolysis oil disclosed herein can convert pyrolysis oil into light aromatics in a single step. Traditionally, pyrolysis oil cannot be upgraded to light aromatics in a single step based on conventional catalysts (such as conventional multi-metallic hydrocracking catalysts). In the systems and methods disclosed herein, pyrolysis oil can be contacted with hydrogen in the presence of a mixed metal oxide catalyst to convert polycyclic aromatic compounds in the pyrolysis oil into light aromatics in a single step.

[0023] As used in this disclosure, "catalyst" may refer to any substance that increases the rate of a particular chemical reaction. The catalysts and catalyst components described in this disclosure may be used to promote various reactions such as, but not limited to, hydrogenation, ring opening, disproportionation, dealkylation, transalkylation, cracking, aromatic cracking, or a combination of these.

[0024] As used in this disclosure, "cracking" may refer to a chemical reaction in which a molecule having a carbon-carbon bond is broken into more than one molecule by the breaking of one or more carbon-carbon bonds; a compound including a cyclic portion (such as an aromatic compound) is converted to a compound that does not include a cyclic portion; or a molecule having a carbon-carbon double bond is reduced to a carbon-carbon single bond. Some catalysts may have multiple forms of catalytic activity, and referring to a catalyst by one particular function does not render the catalyst incapable of catalytic activity for other functions.

[0025] As used in the present disclosure, the term "aromatic compound" may refer to one or more compounds having one or more aromatic ring structures. The term "light aromatic compound" may refer to one or more compounds having an aromatic ring, with or without substitution, and having 6 to 8 carbon atoms. The term "BTEX" may refer to any combination of benzene, toluene, ethylbenzene, p-xylene, m-xylene, and o-xylene.

[0026] As used throughout this disclosure, the term "crude oil" or "whole crude oil" may refer to crude oil received directly from an oil field or a desalting unit, without having any fractions separated by distillation.

[0027] As used throughout this disclosure, the terms "upstream" and "downstream" may refer to the relative positioning of a unit operation with respect to the direction of flow of a process stream. A first unit operation of a system may be considered "upstream" of a second unit operation if a process stream flowing through the system encounters a first unit operation before encountering a second unit operation. Likewise, a second unit operation may be considered "downstream" of the first unit operation if a process stream flowing through the system encounters a first unit operation before encountering a second unit operation.

[0028] As used in this disclosure, passing a stream or effluent "directly" from one unit to another may refer to passing a stream or effluent from a first unit to a second unit without passing the stream or effluent through an intervening reaction system or separation system that substantially changes the composition of the stream or effluent. Heat transfer devices (such as heat exchangers, preheaters, coolers, condensers, or other heat transfer equipment) and pressure devices (such as pumps, pressure regulators, compressors, or other pressure devices) are not considered to be intervening systems that change the composition of a stream or effluent. Combining two streams or effluents together upstream of a process unit is also not considered to include an intervening system that changes the composition of one or both of the combined streams or effluents. Simply dividing a stream into two streams of the same composition is also not considered to include an intervening system that changes the composition of the stream.

[0029] As used in the present disclosure, "separation unit" refers to any separation device that at least partially separates one or more chemicals mixed in a process stream from each other. For example, a separation unit can selectively separate different chemical substances from each other to form one or more chemical fractions. Examples of separation units include, but are not limited to, distillation towers, flash tanks, separation drums, separation tanks, centrifuges, filtration devices, traps, scrubbers, expansion devices, membranes, solvent extraction devices, and the like. It should be understood that the separation process described in the present disclosure may not completely separate all of one chemical component from all of another chemical component. It should be understood that the separation process described in the present disclosure "at least partially" separates different chemical components from each other, and even if it is not explicitly stated, it should be understood that separation may only include partial separation. As used in the present disclosure, one or more chemical components can be "separated" from a process stream to form a new process stream. Typically, a process stream can enter a separation unit and be divided or separated into two or more process streams of desired composition. In addition, in some separation processes, "light fractions" and "heavy fractions" can leave the separation unit separately. Typically, the light fraction stream has a lower boiling point than the heavy fraction stream. In addition, it should be understood that where only one separation unit is shown in a figure or only one separation unit is described, two or more separation units can be used to perform the same or substantially the same separation. For example, where a distillation column with multiple outlets is described, it is contemplated that several separators arranged in series can equally separate the feed stream, and such embodiments are within the scope of the presently described embodiments.

[0030] As used in the present disclosure, the term "effluent" may refer to a stream discharged from a reactor, a reaction zone, or a separation unit after a specific reaction or separation process. Typically, the effluent has a composition different from the stream entering the separation unit, the reactor, or the reaction zone. It should be understood that when the effluent is transported to another system unit, only a portion of the system stream can be transported. For example, a slipstream (having the same composition) can take away some of the effluent, which means that only a portion of the effluent can enter a downstream system unit. The term "reaction effluent" can be more specifically used to refer to a stream discharged from a reactor or a reaction zone.

[0031] It should be further understood that a stream can be named after a component of the stream, and the component for which the stream is named can be the major component of the stream (such as comprising from 50 weight percent (wt.%), from 70 wt.%, from 90 wt.%, from 95 wt.%, from 99 wt.%, from 99.5 wt.%, or even from 99.9 wt.% of the contents of the stream to 100 wt.% of the contents of the stream). It should also be understood that when a stream including the component is disclosed as being transferred from one system component to another system component, the component of the stream is disclosed as being transferred from the system component to the other system component. For example, a "hydrogen gas stream" disclosed as being transferred to a first system component or from a first system component to a second system component should be understood to be equivalently disclosed as being transferred to the first system component or from a first system component to a second system component.

[0032] Reference again Figure 1 , schematically depicting a system 100 for upgrading pyrolysis oil 102. The system 100 for upgrading pyrolysis oil 102 may include a pyrolysis upgrading unit 110 and a separation unit 120 downstream of the pyrolysis upgrading unit 110. The pyrolysis upgrading unit 110 may include one or more reactors and may be operated to contact the pyrolysis oil 102 with hydrogen 104 in the presence of a catalyst to produce a reaction effluent 114. The catalyst is a mixed metal oxide catalyst 106 of the present disclosure. The reaction effluent 114 may be conveyed to the separation unit 120, which may include one or more separation processes or unit operations. The separation unit 120 may be operated to separate the spent mixed metal oxide catalyst from the reaction effluent 114 to produce a reaction product effluent 122 and a spent mixed metal oxide catalyst 124. The reaction product effluent 122 may include light aromatic compounds. In particular, the reaction product effluent 122 may include toluene, benzene, ethylbenzene, xylene, or a combination thereof.

[0033] The pyrolysis oil 102 can be a stream from a hydrocarbon processing facility that is rich in aromatic compounds, such as polycyclic aromatic compounds. In an embodiment, the pyrolysis oil 102 can be an underflow from a steam cracking process. As used in the present disclosure, "underflow" can refer to a portion of the residue or feed (such as the feed to a steam cracking process) including the least volatile components that have not been captured separately as condensed vapor. The pyrolysis oil 102 can include monoaromatic compounds and polycyclic aromatic compounds. Polycyclic aromatic compounds can include aromatic compounds containing 2, 3, 4, 5, 6, 7, 8 or more than 8 aromatic ring structures. The pyrolysis oil 102 can also include other components, such as, but not limited to, saturated hydrocarbons. Reference Figure 2 , graphically depicts the composition of a typical pyrolysis oil 102 produced from steam cracked crude oil in Saudi Arabia. Figure 2As shown, the pyrolysis oil 102 may include monoaromatics, diaromatics, triaromatics, tetraaromatics, pentaaromatics, hexaaromatics, and aromatic compounds having 7 or more aromatic rings ( Figure 2 The pyrolysis oil 102 may include elevated concentrations of diaromatic compounds and aromatic compounds having seven or more aromatic rings, such as Figure 2 As shown. In an embodiment, based on the unit weight of the pyrolysis oil 102, the pyrolysis oil 102 rich in polycyclic aromatic compounds may include greater than or equal to 50 wt.% of polycyclic aromatic compounds, such as greater than or equal to 60 wt.%, greater than or equal to 65 wt.%, greater than or equal to 70 wt.%, greater than or equal to 75 wt.%, or even greater than or equal to 80 wt.% of polycyclic aromatic compounds. Based on the unit weight of the pyrolysis oil 102, the pyrolysis oil 102 may include greater than or equal to 30 wt.% of polycyclic aromatic compounds having greater than or equal to 16 carbon atoms, such as greater than or equal to 35 wt.%, greater than or equal to 40 wt.%, less than or equal to 45 wt.%, greater than or equal to 50 wt.%, or even greater than or equal to 55 wt.% of polycyclic aromatic compounds having greater than or equal to 16 carbon atoms. The pyrolysis oil 102 may also have a low concentration of sulfur and sulfur compounds. The pyrolysis oil 102 may have a concentration of sulfur and sulfur-containing compounds at a concentration less than or equal to 500 parts per million by weight (ppmw), such as less than or equal to 400 ppmw, or even less than or equal to 300 ppmw.

[0034] The system 100 and method of the present disclosure may also be operable to upgrade other carbonaceous resources or other heavy oils that are difficult to process that may have significant concentrations of polycyclic aromatic compounds. Other heavy oils may include, but are not limited to, oil sands bitumen and heavy oil residues.

[0035] In an embodiment, the pyrolysis oil 102 may be diluted with toluene 103 before entering the pyrolysis upgrading unit 110. Due to the high viscosity of the pyrolysis oil 102, toluene 103 may be added as a diluent to increase the fluidity of the pyrolysis oil 102. Adding toluene 103 to the pyrolysis oil 102 may allow the pyrolysis oil 102 to have increased contact with the surface of the mixed metal oxide catalyst 106. The pyrolysis oil 102 and toluene 103 may be mixed at a weight ratio of pyrolysis oil 102 to toluene 103 of 95 / 5 to 65 / 35.

[0036] Reference again Figure 1, the pyrolysis oil 102 can be transported to the pyrolysis upgrading unit 110. The pyrolysis upgrading unit 110 is operable to contact the pyrolysis oil 102 with hydrogen 104 in the presence of a mixed metal oxide catalyst 106 to produce a reaction effluent 114. Contacting the pyrolysis oil 102 with hydrogen 104 in the presence of the mixed metal oxide catalyst 106 can convert polycyclic aromatic compounds having greater than or equal to 16 carbon atoms in the pyrolysis oil 102 into light aromatic compounds. The hydrogen 104 can include a recycled hydrogen stream or supplemental hydrogen from an external hydrogen source inside or outside the refinery boundary. The hydrogen 104 can enter the pyrolysis upgrading unit 110 directly, or can be combined with the pyrolysis oil 102 upstream of the pyrolysis upgrading unit 110. The hydrogen 104 can be used to pressurize the pyrolysis upgrading unit 110 to an operating pressure.

[0037] The pyrolysis upgrading unit 110 may include any type of reactor suitable for contacting the pyrolysis oil 102 with hydrogen 104 in the presence of the mixed metal oxide catalyst 106. Suitable reactors may include, but are not limited to, batch reactors, fixed bed reactors, moving bed reactors, continuous stirred tank reactors, plug flow reactors, thick liquid bed reactors, and ebullient bed reactors, or combinations of these reactors. In an embodiment, the pyrolysis upgrading unit 110 includes one or more batch reactors.

[0038] The mixed metal oxide catalyst 106 is operable to convert polycyclic aromatic compounds having greater than or equal to 16 carbon atoms in the pyrolysis oil 102 into light aromatic compounds. The mixed metal oxide catalyst 106 may include a plurality of catalyst particles. Each of the plurality of catalyst particles may include a plurality of metal oxides. The plurality of metal oxides of the mixed metal oxide catalyst 106 may include oxides of metals in Groups 3-13 of the International Union of Pure and Applied Chemistry (IUPAC) periodic table of elements. In an embodiment, the plurality of metal oxides of the mixed metal oxide catalyst 106 may include oxides of iron, zirconium, cerium, aluminum, tungsten, molybdenum, titanium, or combinations thereof. The mixed metal oxide catalyst 106 may also include oxides of metalloids, such as oxides of silicon. The mixed metal oxide catalyst 106 may include an oxide of a metal or metalloid selected from the group consisting of iron oxide (Fe2O3), zirconium oxide (ZrO2), cerium oxide (CeO2), aluminum oxide (Al2O3), silicon dioxide (SiO2), tungsten oxide (WO3), molybdenum oxide (MoO3), titanium oxide (TiO2), and combinations thereof.

[0039] The mixed metal oxide catalyst 106 may include iron oxide as one of the plurality of metal oxides. In an embodiment, the mixed metal oxide catalyst 106 may include 60 wt.% to 95 wt.% iron oxide, such as 70 wt.% to 90 wt.%, 75 wt.% to 85 wt.%, or 80 wt.% to 85% wt.% iron oxide. The mixed metal oxide catalyst 106 may include zirconium oxide as one of the plurality of metal oxides. In an embodiment, the mixed metal oxide catalyst 106 may include 1 wt.%-20 wt.% zirconium oxide, such as 1 wt.%-15 wt.%, 2.5 wt.%-12.5 wt.%, or 5 wt.%-10 wt.% zirconium oxide. The mixed metal oxide catalyst 106 may include cerium oxide as one of the plurality of metal oxides. In an embodiment, the mixed metal oxide catalyst 106 may include 0.1 wt.%-10 wt.% of cerium oxide, such as 0.5 wt.%-7.5 wt.%, 0.5 wt.%-5 wt.%, or 1 wt.%-5 wt.%. The mixed metal oxide catalyst 106 may include aluminum oxide (Al2O3) as one of the plurality of metal oxides. In an embodiment, the mixed metal oxide catalyst 106 may include aluminum oxide (Al2O3) from 1 wt.% to 20 wt.%, such as 2.5 wt.% to 15 wt.%, 3 wt.% to 12.5 wt.%, or 5 wt.% to 10 wt.%. The weight percentages of the plurality of metal oxides of the mixed metal oxide catalyst 106 are based on the total weight of the mixed metal oxide catalyst 106. The mixed metal oxide catalyst 106 may include (consist of, or consist essentially of): 60 wt.% to 95 wt.% iron oxide, 1 wt.% to 20 wt.% zirconium oxide, 0.1 wt.% to 10 wt.% cerium oxide, and 1 wt.% to 20 wt.% aluminum oxide (Al2O3). In an embodiment, the mixed metal oxide catalyst 106 may include 83 wt.% iron oxide, 7.5 wt.% zirconium oxide, 2.5 wt.% cerium oxide, and 7.0 wt.% aluminum oxide (Al2O3).

[0040] Contacting the pyrolysis oil 102 with hydrogen 104 under reaction conditions in the presence of a mixed metal oxide catalyst 106 can convert at least a portion of the polycyclic aromatic compounds in the pyrolysis oil 102 into light aromatic compounds in a single step without subsequent chemical reaction steps. The conversion of diaromatic and polycyclic aromatic compounds into light aromatic compounds, such as benzene, toluene, ethylbenzene, and xylenes, is a complex reaction scheme involving multiple simultaneous and selective reactions, which may include selective hydrogenation of one aromatic ring in the compound, but not all, followed by ring opening of saturated cycloalkane rings, hydrodealkylation, transalkylation, and disproportionation reactions. Without being bound by any particular theory, it is believed that upgrading the pyrolysis oil 102 can include selective hydrogenation of at least one aromatic ring structure or polycyclic aromatic compound to produce a molecule having one or more aromatic rings and at least one saturated ring. The saturated ring portion can then undergo ring opening to produce substituted aromatic compounds. The substituted aromatic compounds can then undergo one or more of hydroalkylation, transalkylation, or disproportionation to produce light aromatic compounds. It should be understood that many variations and combinations of these reactions and other chemical reactions may occur during the upgrading process. This complex sequence of simultaneous reactions for upgrading the pyrolysis oil 102 may be catalyzed using a mixed metal oxide catalyst 106 .

[0041] The pyrolysis upgrading unit 110 may contact the pyrolysis oil 102 with hydrogen 104 in the presence of the mixed metal oxide catalyst 106 under operating conditions sufficient to upgrade at least a portion of the polycyclic aromatic compounds in the pyrolysis oil 102 to produce a reaction effluent 114, wherein the reaction effluent 114 includes light aromatic compounds. The pyrolysis upgrading unit 110 may be operated at an operating temperature in the range of 300 degrees Celsius (° C.) to 500° C. (such as 350° C. to 500° C., 400° C. to 500° C., 450° C. to 500° C., 350° C. to 450° C., or 400° C. to 450° C.) and at an operating pressure of 1 megapascal (MPa) (10 bar) to 20 MPa (200 bar), such as 3 MPa (30 bar) to 18 MPa (180 bar) or 5 MPa (50 bar) to 16 MPa (160 bar). The weight ratio of the mixed metal oxide catalyst 106 to the pyrolysis oil 102 in the reactor may be in the range of 0.1 to 1, such as 0.1 to 0.6, 0.3 to 1.0, or 0.3 to 0.6.

[0042] Under the operating conditions of the pyrolysis upgrading unit 110, contacting the pyrolysis oil 102 with the hydrogen 104 in the presence of the mixed metal oxide catalyst 106 can cause at least a portion of the polycyclic aromatic compounds in the pyrolysis oil 102 to undergo multiple simultaneous and selective reactions to form light aromatic compounds. Contacting the pyrolysis oil 102 with the hydrogen 104 in the presence of the mixed metal oxide catalyst 106 can result in a yield of greater than or equal to 30 wt.% of light aromatic compounds, such as greater than or equal to 35 wt.%, greater than or equal to 40 wt.%, less than or equal to 45 wt.%, or greater than or equal to 50 wt.% of light aromatic compounds, based on the total weight of the reaction effluent 114.

[0043] The pyrolysis upgrading unit 110 may include one or more vapor outlets operable to discharge gaseous components as a gaseous component effluent 112 from the pyrolysis upgrading unit 110. The one or more vapor outlets may be operable to separate the gaseous component effluent 112 from the reaction effluent 114 after contacting the pyrolysis oil 102 with the hydrogen 104 in the presence of the mixed metal oxide 106. The gaseous components of the gaseous component effluent 112 may include, but are not limited to, excess hydrogen 104, light hydrocarbons (e.g., methane, ethane, etc.), sulfur components (e.g., hydrogen sulfide (H2S)), or combinations thereof. After upgrading the pyrolysis oil 102, the gaseous component effluent 112 may include at least 90 wt.%, at least 95 wt.%, at least 98 wt.%, at least 99 wt.%, or even at least 99.9 wt.% of the gaseous components produced in the pyrolysis upgrading unit 110, wherein the gaseous components generally refer to compounds that are gaseous under the reaction conditions in the pyrolysis upgrading unit 110. The gaseous component effluent 112 may also include excess hydrogen 104. The gaseous component effluent 112 may be sent to one or more downstream processing processes, such as, but not limited to, a process to recover any light aromatic compounds from the gaseous component effluent 112, separation of excess hydrogen, removal of one or more contaminants, or other processes.

[0044] The pyrolysis upgrading unit 110 may be in fluid communication with the separation unit 120 so that the reaction effluent 114 enters the separation unit 120 from the pyrolysis upgrading unit 110. The reaction effluent 114 may include light aromatic compounds. The light aromatic compounds may include aromatic hydrocarbons having 6 to 13 carbon atoms. For example, the light aromatic compounds may include benzene, toluene, ethylbenzene, xylene, or a combination thereof. The reaction effluent 114 may include at least 90wt.%, at least 95wt.%, at least 98wt.%, at least 99wt.%, or even at least 99.9wt.% of the light aromatic compounds produced in the pyrolysis upgrading unit 110. The reaction effluent 114 may also include any unreacted components of the mixed metal oxide catalyst 106 and the pyrolysis oil 102, such as unreacted heavy aromatic compounds.

[0045] Reference again Figure 1 , the reaction effluent 114 can be transported to the separation unit 120. The separation unit 120 can be directly downstream of the pyrolysis upgrading unit 110, so that the reaction effluent 114 can enter the separation unit 120 directly from the pyrolysis upgrading unit 110 without passing through any intermediate reactor or unit operation. The separation unit 120 may include one or more separation units. The separation unit 120 is operable to separate the reaction effluent 114 into at least a reaction product effluent 122 and a spent mixed metal oxide catalyst 124. The separation unit 120 may include a solid-liquid separation device that is operable to separate the reaction effluent 114 into at least one reaction product effluent 122 and a spent mixed metal oxide catalyst 124. In an embodiment, the separation unit 120 may include a centrifuge. The separation unit 120 is operable to separate the reaction effluent 114 into at least a reaction product effluent 122 and a spent mixed metal oxide catalyst 124 by centrifugation.

[0046] Despite Figure 1 The separation unit 120 is depicted as separating the reaction effluent 114 into a reaction product effluent 122 comprising light aromatic compounds and a spent mixed metal oxide catalyst 124. It is understood that the separation unit 120 is operable to separate the reaction effluent 114 into a plurality of reaction product effluents, one or more of which may include light aromatic compounds. In an embodiment, the separation unit 120 may include a distillation unit or a fractionation unit downstream of the solid-liquid separation unit. The distillation unit or the fractionation unit is operable to separate the reaction product effluent 122 into a plurality of reaction product effluents. The reaction product effluent 122 may be sent to one or more downstream processes for further separation, treatment or processing.

[0047] Reference now Figure 3 , the system 100 may include a spent catalyst treatment unit 230 downstream of the separation unit 120. Contacting the pyrolysis oil 102 with the hydrogen 104 under reaction conditions in the presence of the mixed metal oxide catalyst 106 may produce a condensate, which may be deposited on the mixed metal oxide catalyst 106. When the condensate is deposited on the mixed metal oxide catalyst 106, a spent mixed metal oxide catalyst 124 may be produced. The spent catalyst treatment unit 230 may be used to regenerate the spent mixed metal oxide catalyst 124. The spent catalyst treatment unit 230 may be operable to wash the spent mixed metal oxide catalyst 124 with toluene 228 to remove at least a portion of the condensate from the spent mixed metal oxide catalyst 124. Excess toluene 234 from the spent catalyst treatment unit 230 may be discharged from the spent catalyst treatment unit 230 and combined with the reaction product effluent 122.

[0048] The spent catalyst treatment unit 230 may also be operable to vacuum dry the spent mixed metal oxide catalyst 124 after washing. The spent catalyst treatment unit 230 may be operable to first vacuum dry the spent mixed metal oxide catalyst 124 at a temperature of 20°C to 30°C, and then vacuum dry at a temperature greater than 80°C. The spent catalyst treatment unit 230 may also be operable to calcine the spent mixed metal oxide catalyst 124 to produce a treated mixed metal oxide catalyst 232. In an embodiment, the spent catalyst treatment unit 230 may calcine the spent mixed metal oxide catalyst 124 in air at a temperature greater than 400°C for six hours or more. The treated mixed metal oxide catalyst 232 may be discharged from the spent catalyst treatment unit 230 and returned to the pyrolysis upgrading unit 110 for use as a mixed metal oxide catalyst 106.

[0049] Reference again Figure 1 , a method for upgrading pyrolysis oil 102 may include contacting pyrolysis oil 102 with hydrogen 104 under reaction conditions in the presence of mixed metal oxide catalyst 106 to produce a reaction effluent 114 comprising light aromatic compounds. As previously described in the present disclosure, contacting pyrolysis oil 102 with hydrogen 104 under reaction conditions in the presence of mixed metal oxide catalyst 106 may convert at least a portion of polycyclic aromatic compounds in pyrolysis oil 102 into light aromatic compounds. The reaction conditions may include: a temperature of 200° C. to 500° C., a pressure of 1 MPa (10 bar) to 20 MPa (200 bar), a weight ratio of mixed metal oxide catalyst 106 to pyrolysis oil 102 in the reactor may be in the range of 0.1 to 1, or a combination of these reaction conditions.

[0050] The method may include contacting the pyrolysis oil 102 with hydrogen 104 in the presence of a mixed metal oxide catalyst 106 in a pyrolysis upgrading unit 110 to produce a reaction effluent 114. The pyrolysis upgrading unit 110 may have any of the features, catalysts, or operating conditions previously discussed in this disclosure for a pyrolysis upgrading unit 110. The method may also include separating the reaction effluent 114 in a separation unit 120 to produce at least one reaction product effluent 122 and a spent mixed metal oxide catalyst 124. The separation unit 120 may have any of the features, catalysts, or operating conditions previously discussed in this disclosure for a separation unit 120.

[0051] The method may include washing and drying the spent mixed metal oxide catalyst 124. The spent mixed metal oxide catalyst 124 may be washed with toluene 228 to remove at least a portion of the condensate from the spent mixed metal oxide catalyst 124. It is contemplated that the spent mixed metal oxide catalyst 124 may additionally or alternatively be washed with other solvents, such as, but not limited to, benzene, ethylbenzene, or xylenes, to remove at least a portion of the condensate from the spent mixed metal oxide catalyst 124. The spent mixed metal oxide catalyst 124 may be washed and dried in a spent catalyst treatment unit 230. The spent catalyst treatment unit 230 may have any of the features, catalysts, or operating conditions previously discussed in this disclosure for a spent catalyst treatment unit 230.

[0052] Example

[0053] Various embodiments of the heavy oil processing method and system will be further illustrated by the following examples. These examples are illustrative in nature and should not be construed as limiting the subject matter of the present disclosure.

[0054] Example 1: Preparation of mixed metal oxide catalysts

[0055] To prepare a mixed metal oxide catalyst including iron oxide, zirconium oxide, cerium oxide, and aluminum oxide, 50 g of iron (III) nitrate nonahydrate (Fe(NO3)3·9H2O) was dissolved in 800 mL of distilled water to prepare solution A. Then, other metal oxide precursors were added to solution A. Specifically, 4.906 g of aluminum nitrate nonahydrate (Al(NO3)3·9H2O), 1.549 g of zirconium (IV) nitrate oxide hydrate (ZrO(NO3)2:3H2O), and 0.601 g of cerium (III) nitrate hexahydrate (Ce(NO3)3·6H2O) were added to solution A to form solution B. Solution B was then stirred for 30 minutes.

[0056] An ammonia solution, Solution C, was prepared by adding 40 mL of ammonium hydroxide (NH4OH) (based on 28-30% NH3) to 60 mL of distilled water. Solution C was slowly added to Solution B to produce Solution D. Solution C was added until the pH of Solution D reached approximately 7. Solution D was then stirred for another hour.

[0057] After preparing solution D and stirring for another hour, the precipitate was separated from solution D and dried in an oven overnight (i.e., about 12 hours). The dried precipitate was then calcined at 500° C. in air for two hours. After calcination, the dried calcined precipitate was crushed to obtain the final mixed metal oxide catalyst.

[0058] Example 2: Upgrading pyrolysis oil in the presence of mixed metal oxide catalysts

[0059] In Example 2, the performance of the mixed metal oxide catalyst for upgrading pyrolysis oil of Example 1 was evaluated. 16.74 grams of pyrolysis oil and 12.17 grams of the mixed metal oxide catalyst of Example 1 were added to a batch reactor and mixed. Before adding the pyrolysis oil, the pyrolysis oil was mixed with 4.37 grams of toluene as a diluent to increase the fluidity of the pyrolysis oil so that the pyrolysis oil could fully contact the surface of the mixed metal oxide catalyst.

[0060] After adding the pyrolysis oil (containing toluene) and the mixed metal oxide catalyst into the batch reactor at atmospheric pressure and room temperature, the batch reactor was sealed. The batch reactor was purged with pure hydrogen three times. The pressure was then increased to 140 bar (14 MPa) by introducing pure hydrogen at room temperature. The pyrolysis oil (containing toluene) and the mixed metal oxide catalyst were then heated to 400° C. and stirred continuously for 4 hours.

[0061] After the reaction is finished, the batch reactor is cooled to room temperature. Then, the gas mixture is released and collected in a gas bag. The gas mixture is analyzed using gas chromatography. The reaction effluent is transferred to a separation unit (centrifuge). The reaction effluent is centrifuged at 10,000 revolutions per minute (rpm) for 20 minutes. After centrifugation, two layers are obtained, the top layer contains the reaction product, and the bottom layer contains the used mixed metal oxide catalyst. The used mixed metal oxide catalyst is then washed with toluene to remove any condensate and then vacuum dried. The used mixed metal oxide catalyst is first vacuum dried at room temperature and then vacuum dried at 100°C. The reaction product effluent is analyzed by simulated distillation (SIMDIS) gas chromatography, paraffin, isoparaffin, olefin, cycloparaffin and aromatic hydrocarbons (PIONA) gas chromatograph and high performance liquid chromatography (HPLC).

[0062] Table 1 provides the reaction conditions, characteristics of the pyrolysis oil, and characteristics of the reaction effluent.

[0063] Table 1. Reaction conditions, characteristics of pyrolysis oil and characteristics of reaction effluent

[0064] parameter value Reaction temperature (℃) 400 Total pressure before heating to reaction temperature (MPa) 14 Running time (hours) 4 <![CDATA[C in pyrolysis oil 16 and C 16+ (wt.%)]]> 41.3 <![CDATA[C in the reaction effluent 16 and C 16+ (wt.%)]]> 0.5 <![CDATA[C 16 and C 16+ Conversion rate (%)]]> 98.8 <![CDATA[Conversion rate of H2 (%)]]> 33.5 Gas product yield (wt.%) 3.9 <![CDATA[Liquid product yield 1 (wt.%)]]> 96.1 <![CDATA[Yield of monoaromatic hydrocarbons (C6-C9) (wt.%)]]> 41.3 <![CDATA[Yield of diaromatic hydrocarbons (wt.%) 10 -C 13 )]]> 40.8 <![CDATA[Yield (wt.%) of triaromatic hydrocarbons (C 14 -C 16 )]]> 14.4 Coke / Raw Material (%) 0

[0065] 1 The toluene diluent was not considered a product.

[0066] As shown in Table 1, the mixed metal oxide catalyst effectively converted 98.8% of tetraaromatic hydrocarbons (C 16 and C 16+ The liquid product yield includes 41.3 wt.% monoaromatics and 40.8 wt.% diaromatics.

[0067] One or more aspects of the present disclosure are described herein. A first aspect of the present disclosure may include a method for upgrading a pyrolysis oil, the method comprising contacting the pyrolysis oil with hydrogen under reaction conditions in the presence of a mixed metal oxide catalyst to produce a reaction effluent comprising light aromatic compounds. The pyrolysis oil may include polycyclic aromatic compounds. The mixed metal oxide catalyst may include a plurality of catalyst particles, and each of the plurality of catalyst particles may include a plurality of metal oxides. Contacting the pyrolysis oil with hydrogen under reaction conditions in the presence of a mixed metal oxide catalyst may convert at least a portion of the polycyclic aromatic compounds in the pyrolysis oil into light aromatic compounds.

[0068] A second aspect of the present disclosure may include the first aspect, wherein the pyrolysis oil may include greater than or equal to 30 weight percent (wt. %) of polycyclic aromatic compounds having greater than or equal to 16 carbon atoms, based on the total weight of the pyrolysis oil.

[0069] A third aspect of the present disclosure may include the first aspect or the second aspect, comprising contacting pyrolysis oil with hydrogen in the presence of a mixed metal oxide catalyst in a pyrolysis upgrading unit to produce a reaction effluent.

[0070] A fourth aspect of the present disclosure may include any one of the first to third aspects, including contacting the pyrolysis oil with hydrogen in the presence of a mixed metal oxide catalyst at a temperature of 300 degrees Celsius (° C.) to 500° C.

[0071] A fifth aspect of the present disclosure may include any one of the first to fourth aspects, including contacting the pyrolysis oil with hydrogen in the presence of a mixed metal oxide catalyst at a pressure of 1 MPa (10 bar) to 20 MPa (200 bar).

[0072] A sixth aspect of the present disclosure may include any one of the first to fifth aspects, wherein the plurality of metal oxides of the mixed metal oxide catalyst include oxides of metals of Groups 3-13 of the IUPAC Periodic Table of Elements.

[0073] The seventh aspect of the present disclosure may include any one of the first to sixth aspects, wherein the multiple metal oxides of the mixed metal oxide catalyst may include iron oxide, zirconium oxide, cerium oxide, aluminum oxide, tungsten oxide, molybdenum oxide, titanium oxide, or a combination thereof.

[0074] An eighth aspect of the present disclosure may include the seventh aspect, wherein the mixed metal oxide catalyst may include 60wt.%-95wt.% iron oxide, 1wt.%-20wt.% zirconium oxide, 0.1wt.%-10wt.% cerium oxide and 1wt.%-20wt.% aluminum oxide, wherein the weight percentages are based on the total weight of the mixed metal oxide catalyst.

[0075] A ninth aspect of the present disclosure may include any one of the first to eighth aspects, wherein the light aromatic compound may include aromatic hydrocarbons having 6 to 13 carbon atoms.

[0076] A tenth aspect of the present disclosure may include any one of the first to ninth aspects, wherein the light aromatic compounds may include benzene, toluene, ethylbenzene, xylene, or a combination thereof.

[0077] An eleventh aspect of the present disclosure may include any one of the first to tenth aspects, wherein contacting pyrolysis oil with hydrogen under reaction conditions in the presence of a mixed metal oxide catalyst can convert a portion of polycyclic aromatic compounds in the pyrolysis oil into light aromatic compounds in a single step without performing a subsequent chemical reaction step.

[0078] A twelfth aspect of the present disclosure may include any one of the first to eleventh aspects, wherein contacting pyrolysis oil with hydrogen in the presence of a mixed metal oxide catalyst can yield a yield of light aromatic compounds greater than or equal to 30 wt. % based on the total weight of the reaction effluent.

[0079] A thirteenth aspect of the present disclosure may include any one of the first to twelfth aspects, further comprising mixing the pyrolysis oil with toluene before contacting the pyrolysis oil with hydrogen in the presence of a mixed metal oxide catalyst.

[0080] A fourteenth aspect of the present disclosure may include the thirteenth aspect, including mixing the pyrolysis oil and toluene in a weight ratio of the pyrolysis oil to the toluene of 95 / 5 to 65 / 35.

[0081] A fifteenth aspect of the present disclosure may include any one of the first to fourteenth aspects, further comprising separating gaseous components from the reaction effluent after contacting the pyrolysis oil with hydrogen in the presence of the mixed metal oxide to produce a liquid portion of the reaction effluent.

[0082] A sixteenth aspect of the present disclosure may include any of the first to fifteenth aspects, further comprising separating the spent mixed metal oxide catalyst in the liquid portion of the reaction effluent to produce a reaction product comprising light aromatic compounds.

[0083] A seventeenth aspect of the present disclosure may include the sixteenth aspect, comprising separating the spent mixed metal oxide catalyst in a liquid portion of the reaction effluent in a separation unit to produce a reaction product.

[0084] An eighteenth aspect of the present disclosure may include the sixteenth aspect or the seventeenth aspect, wherein the separation unit may include a centrifuge.

[0085] A nineteenth aspect of the present disclosure may include any one of the first to eighteenth aspects, further comprising washing and drying the used mixed metal oxide catalyst.

[0086] The twentieth aspect of the present disclosure may include the nineteenth aspect, wherein contacting pyrolysis oil with hydrogen under reaction conditions in the presence of a mixed metal oxide catalyst may produce a condensate, which may be deposited on the mixed metal oxide catalyst to produce a used mixed metal oxide catalyst, and the method may further include washing the used mixed metal oxide catalyst with toluene to remove at least a portion of the condensate from the used mixed metal oxide catalyst.

[0087] A twenty-first aspect of the present disclosure may include the nineteenth aspect or the twentieth aspect, comprising first vacuum drying the used mixed metal oxide catalyst at a temperature of 20°C to 30°C, and then vacuum drying at a temperature greater than 80°C.

[0088] The twenty-second aspect of the present disclosure may include a system for upgrading pyrolysis oil, the system including a pyrolysis upgrading unit, the pyrolysis upgrading unit including a mixed metal oxide catalyst. The mixed metal oxide catalyst may include a plurality of catalyst particles, and each of the plurality of catalyst particles may include a plurality of metal oxides. The pyrolysis upgrading unit is operable to contact the pyrolysis oil with hydrogen in the presence of the mixed metal oxide catalyst to produce a reaction effluent. The system may also include a separation unit disposed downstream of the pyrolysis upgrading unit. The separation unit is operable to separate the spent mixed metal oxide catalyst from the reaction effluent to produce a reaction product comprising light aromatic compounds.

[0089] The twenty-third aspect of the present disclosure may include the twenty-second aspect, wherein the pyrolysis upgrading unit may be operated to contact the pyrolysis oil with hydrogen in the presence of a mixed metal oxide catalyst, at a temperature of 300°C to 500°C and a pressure of 1 MPa (10 bar) to 20 MPa (200 bar) to produce a reaction effluent.

[0090] A twenty-fourth aspect of the present disclosure may include the twenty-second aspect or the twenty-third aspect, wherein the separation unit is located directly downstream of the pyrolysis upgrading unit.

[0091] A twenty-fifth aspect of the present disclosure may include any one of the twenty-second to twenty-fourth aspects, wherein the separation unit includes a centrifuge.

[0092] As used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. The verb "comprise" and its conjugated forms should be interpreted as referring to elements, components, or steps in a non-exclusive manner. The referenced elements, components, or steps may be present, employed, or combined with other elements, components, or steps that are not explicitly referenced. For the purposes of defining the present technology, the transition phrase "consisting of" may be introduced into the claims as a closed preamble term to limit the scope of the claim to the listed components or steps and any naturally occurring impurities. For the purposes of defining the present technology, the transition phrase "consisting essentially of" may be introduced into the claims to limit the scope of one or more claims to the listed elements, components, materials, or method steps and any unlisted elements, components, materials, or method steps that do not materially affect the novel features of the claimed subject matter. The transitional phrases "consisting of" and "consisting essentially of" may be construed as subsets of open transitional phrases such as "comprising" and "including" so that any use of an open phrase to introduce a recitation of a list of elements, components, materials, or steps should be construed to also disclose the recitation of the list of elements, components, materials, or steps using the closed terms "consisting of" and "consisting essentially of." For example, a recitation of a composition "comprising" components A, B, and C should be construed to also disclose a composition "consisting of components A, B, and C" as well as a composition "consisting essentially of components A, B, and C." Any quantitative value expressed in this application may be considered to include open embodiments consistent with the transitional phrases "comprising" or "including," as well as closed or partially closed embodiments consistent with the transitional phrases "consisting of" and "consisting essentially of."

[0093] It should be noted that one or more of the claims utilize the term "wherein" as a transitional phrase. For purposes of defining the present technology, it should be noted that this term is introduced in the claims as an open transitional phrase to introduce a recitation of a series of features of the structure and should be interpreted in a manner similar to the more commonly used open introductory term "comprising."

[0094] It should be understood that any two quantitative values ​​assigned to a property may form a range for that property, and all combinations of ranges formed by all specified quantitative values ​​for a given property are contemplated in the present disclosure.

[0095] Having described the subject matter of the present disclosure in detail and with reference to specific embodiments, it should be noted that the various details described in the present disclosure should not be considered to imply that these details relate to elements that are essential components of the various embodiments described in the present disclosure, even in the case where a particular element is shown in each of the drawings accompanying the present specification. On the contrary, the claims appended hereto should be considered as the only indication of the breadth of the present disclosure and the corresponding scope of the various embodiments described in the present disclosure. Moreover, it is apparent that modifications and changes may be made without departing from the scope of the appended claims.

Claims

1. A method for upgrading pyrolysis oil, the method comprising: contacting the pyrolysis oil with hydrogen in the presence of a mixed metal oxide catalyst under reaction conditions to produce a reaction effluent comprising light aromatic compounds, wherein: The pyrolysis oil includes polycyclic aromatic compounds; The mixed metal oxide catalyst comprises: 60 wt.% to 95 wt.% iron oxide; 1 wt.% to 20 wt.% zirconium oxide; 0.1 wt.% to 10 wt.% cerium oxide; and 1wt.% to 20wt.% of aluminum oxide, wherein the weight percentages are based on the total weight of the mixed metal oxide catalyst; and Contacting the pyrolysis oil with hydrogen in the presence of a mixed metal oxide catalyst under reaction conditions converts at least a portion of the polycyclic aromatic compounds in the pyrolysis oil to the light aromatic compounds.

2. The method according to claim 1, wherein: The pyrolysis oil includes greater than or equal to 30 weight percent (wt. %) of polycyclic aromatic compounds having greater than or equal to 16 carbon atoms, based on the total weight of the pyrolysis oil.

3. The method according to claim 1, comprising: The pyrolysis oil is contacted with hydrogen in the presence of the mixed metal oxide catalyst at a temperature of 300 degrees Celsius (° C.) to 500° C., a pressure of 1 megapascal (MPa) (10 bar) to 20 MPa (200 bar), or both.

4. The method according to claim 1, wherein the light aromatic compound comprises aromatic hydrocarbons having 6 to 13 carbon atoms, or wherein the light aromatic compound comprises benzene, toluene, ethylbenzene, xylene, or a combination thereof.

5. The method of any one of claims 1-4, further comprising mixing the pyrolysis oil with toluene before contacting the pyrolysis oil with hydrogen in the presence of the mixed metal oxide catalyst.

6. The method of claim 5, comprising mixing the pyrolysis oil and toluene in a weight ratio of pyrolysis oil to toluene of 95 / 5 to 65 / 35.

7. The method of any one of claims 1-4, further comprising separating gaseous components from the reaction effluent after contacting the pyrolysis oil with hydrogen in the presence of the mixed metal oxide to produce a liquid portion of the reaction effluent.

8. The process of any one of claims 1-4, further comprising separating the reaction effluent to produce a spent mixed metal oxide catalyst and a reaction product comprising light aromatic compounds.

9. The method of claim 8, comprising separating the reaction effluent in a separation unit to produce the spent mixed metal oxide catalyst and the reaction product, wherein the separation unit comprises a centrifuge.

10. The method of claim 9, wherein contacting the pyrolysis oil with hydrogen under the reaction conditions in the presence of the mixed metal oxide catalyst produces a condensate, the condensate is deposited on the mixed metal oxide catalyst to produce the used mixed metal oxide catalyst, and the method further comprises washing the used mixed metal oxide catalyst with toluene to remove at least a portion of the condensate from the used mixed metal oxide catalyst.

11. The method of claim 9, comprising first vacuum drying the used mixed metal oxide catalyst at a temperature of 20°C to 30°C and then vacuum drying at a temperature greater than 80°C.

12. The method according to any one of claims 1 to 4, wherein: Contacting the pyrolysis oil with hydrogen under reactive conditions in the presence of the mixed metal oxide catalyst converts a portion of the polycyclic aromatic compounds in the pyrolysis oil to light aromatic compounds in a single step without subsequent chemical reaction steps.

13. The method according to any one of claims 1 to 4, wherein: Contacting the pyrolysis oil with hydrogen in the presence of the mixed metal oxide catalyst provides a yield of light aromatic compounds greater than or equal to 30 wt. %, based on the total weight of the reaction effluent.

14. A system for upgrading pyrolysis oil, the system comprising: A pyrolysis upgrading unit, comprising a mixed metal oxide catalyst, wherein: The mixed metal oxide catalyst comprises: 60 wt.% to 95 wt.% iron oxide; 1 wt.% to 20 wt.% zirconium oxide; 0.1 wt.% to 10 wt.% cerium oxide; and 1wt.% to 20wt.% of aluminum oxide, wherein the weight percentages are based on the total weight of the mixed metal oxide catalyst; and The pyrolysis upgrading unit is operable to contact the pyrolysis oil with hydrogen in the presence of the mixed metal oxide catalyst to produce a reaction effluent; and A separation unit is disposed downstream of the pyrolysis upgrading unit and is operable to separate the spent mixed metal oxide catalyst from the reaction effluent to produce a reaction product comprising light aromatic compounds.

15. The system of claim 14, wherein: The separation unit is directly downstream of the pyrolysis upgrading unit, wherein the separation unit comprises a centrifuge.

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