Systems and methods of producing HEX-1-ENE involving metathesis of a c4 stream

Abstract

One method disclosed herein includes: metathesizing a but-1-ene-rich stream having a but-1-ene content of at least 15 molar percent (mol.%) to produce a metathesis product stream containing ethene, propene, and C4-C6 olefins; separating the metathesis product stream into a C2-C3 stream and a C4+-rich stream; separating the C2-C3 stream into an ethene product stream and a propene product stream; separating the C4+-rich stream into a C4 olefin stream and a C5-C6 olefin stream; separating the C5-C6 olefin stream into a C5 olefin stream and a C6 olefin stream; performing C6 isomerization of the C6 olefin stream to produce a hex-1-ene-rich stream; performing C4 isomerization of the C4 olefin stream to produce a butene recycle stream that is combined with the but-1-ene-rich stream prior to metathesis; and a C6 fractionator configured to receive and separate the hex-1-ene-rich stream into a hex-1-ene product stream and a hex-2-enes / hex-3-enes stream.

Description

SYSTEMS AND METHODS OF PRODUCING HEX-l-ENE INVOLVINGMETATHESIS OF A C4STREAMCross-Reference to Related Applications

[0001] This application claims priority to and the benefit of European Application No. EP23216347.7, filed on December 13, 2023. The contents of the referenced application are incorporated into the present application by reference.Technical Field

[0002] The disclosure relates to the production of ethylene, propylene and hex-l-ene using metathesis reactions.Background

[0003] As the demand for hex-l-ene increases, there exists an opportunity to produce hex-l-ene without the consumption of high value ethene. Current hex- 1 -ene production systems lose valuable C4olefins from the system during the production of hex-l-ene. Minimizing the amount of valuable C4olefins lost from the system during the production of hex-l-ene provides an opportunity to achieve greater but- 1 -ene conversion into hex-l-ene.Summary

[0004] Applicant has identified a need for the reduction of valuable C4olefins lost during the production of hex-l-ene through the metathesis process. Provided here are systems and methods to address these shortcomings of the art and provide other additional or alternative advantages. The disclosure herein provides several examples of systems for producing hex-l-ene and methods for producing hex-l-ene through the metathesis process.

[0005] An example hex-l-ene production system disclosed herein includes a metathesis reactor configured to receive and metathesize a but-l-ene-rich stream having a but- 1 -ene content of at least 15 molar percent (mol.%) to produce a metathesis product stream containing ethene, propene, and C4-C6olefins. The system includes a C3 column configured to receive and separate the metathesis product stream into a C2-C3 stream and a C4+-rich stream. The system includes a C2 / C3 splitter configured to receive and separate the C2-C3 stream into an ethene product stream and a propene product stream. The system includes a C4column configured to receive and separate theC4+-rich stream into a C4 olefin stream and a C5-C6 olefin stream. The system includes a C5 column configured to receive and separate the C5-C6 olefin stream into a C5 olefin stream and a Ce olefin stream. The system includes a Ce isomerization reactor configured to receive and perform Ce isomerization of the Ce olefin stream to produce a hex- 1-ene- rich stream, in which hex-2-enes and hex-3-enes of the Ce olefin stream are converted into hex-1 -ene during Ce isomerization. The system includes a C4 isomerization reactor configured to receive and perform C4 isomerization of the C4 olefin stream to produce a butene recycle stream that is provided to the metathesis reactor along with the but-l-ene-rich stream to produce the metathesis product stream, in which but-2- enes of the C4 olefin stream are converted into but- 1 -ene during C4 isomerization. The system includes a Ce fractionator configured to receive and separate the hex-l-ene-rich stream into a hex-1-ene product stream and a hex-2-enes / hex-3-enes stream.

[0006] In certain examples, the metathesis reactor is configured to operate at a temperature ranging from about 35 degrees Celsius (°C) to about 120 °C and a pressure ranging from about 1 barg to about 20 barg. In certain examples, the metathesis reactor is configured to operate at temperature ranging from about 50 °C to about 120 °C and a pressure ranging from about 8 barg gauge (barg) to about 15 barg. In certain examples, the but-l-ene-rich stream contains but- 1 -ene, but-2-enes, and 2-methylpropene. In certain examples, the C3 column includes from about 40 stages to about 60 stages, the C2 / C3 splitter includes from about 20 stages to about 40 stages, the C4 column includes from about 20 to about 40 stages, the C5 column includes from about 20 stages to about 40 stages, and the Ce fractionator includes from about 150 stages to about 200 stages. In certain examples, the C3 column is configured to operate at a pressure ranging from about 5 barg to about 10 barg, the C2 / C3 splitter is configured to operate at a pressure of about 25 barg, the C4 column is configured to operate at a pressure ranging from about 2 barg to about 8 barg, the C5 column is configured operate at a pressure ranging from about 2 barg to about 5 barg, and the Ce fractionator is configured to operate at a pressure ranging from 1 barg to 20 barg. In certain examples, the hex-2-enes / hex-3-enes stream is recycled to the Ce isomerization reactor for Ce isomerization to produce the hex-l-ene-rich stream. In certain examples, at least a portion of the ethene product stream is supplied to the metathesis reactor as a co-feed. In certain examples, the metathesis reactor includes a rhenium oxide-coated y-alumina-based metathesis catalyst, and the C4 isomerization reactor and the Ce isomerization reactor include a potassium oxide-coated y-alumina-based isomerization catalyst.

[0007] In certain examples, the system includes a pre-isomerization reactor configured to receive and isomerize a C4 stream having a but-l-ene content of less than 15 mol.% to produce the but-1- ene-rich stream that is received and metathesized by the metathesis reactor. In certain examples, each of the pre-isomerization reactor, the C4 isomerization reactor, and the Ce isomerization reactor includes a potassium oxide-coated y-alumina-based isomerization catalyst, and each of the pre- isomerization reactor, the C4 isomerization reactor, and the Ce isomerization reactor is configured to operate at a temperature ranging from about 25 °C to about 500 °C and an operating pressure from about 1 barg to about 20 barg. In certain examples, each of the pre-isomerization reactor, the C4 isomerization reactor, and the Ce isomerization reactor is configured to operate at a temperature ranging from about 350 °C to about 500 °C.

[0008] In certain examples, a C4 purge stream is extracted from the C4 olefin stream and a Ce purge stream is extracted from the hex-l-ene-rich stream, the C4 purge stream containing C4 paraffins and C4 olefins, and the Ce purge stream containing Ce paraffins and Ce olefins. In certain examples, the system includes a C4-C6 catalytic cracking reactor configured to receive and catalytically crack the C5 olefin stream, the C4 purge stream, and the Ce purge stream to produce a cracked product stream substantially containing ethene and propene, and also containing hydrogen (H2) and other C1-9 hydrocarbons. In certain examples, the C4-C6 catalytic cracking reactor includes a ZSM-5- based cracking catalyst, and the C4-C6 catalytic cracking reactor is configured to operate at a temperature ranging from about 450 °C to about 650 °C.

[0009] An example method for producing disclosed herein includes the steps of metathesizing a but-l-ene-rich stream having a but-l-ene content of at least mol.% to produce a metathesis product stream containing ethene, propene, and C4-C6 olefins. The method includes the steps of separating the metathesis product stream into a C2-C3 stream and a C4+-rich stream. The method includes the steps of separating the C2-C3 stream into an ethene product stream and a propene product stream. The method includes the steps of separating the C4+-rich stream into a C4 olefin stream and a C5- Ce olefin stream. The method includes the steps of separating the Cs-Ce olefin stream into a C5 olefin stream and a Ce olefin stream. The method includes the steps of performing Ce isomerization of the Ce olefin stream to produce a hex-l-ene-rich stream, in which hex-2-enes and hex-3-enes of the Ce olefin stream are converted into hex-l-ene during Ce isomerization. The method includes the steps of performing C4 isomerization of the C4 olefin stream to produce a butene recycle stream that is combined with the but-l-ene-rich stream prior to metathesis, in which but-2-enes of the C4olefin stream are converted into but-l-ene during C4 isomerization. The method includes the steps of separating the hex-l-ene-rich stream into a hex-l-ene product stream and a hex-2-enes / hex-3- enes stream.

[0010] In certain examples, metathesizing the but-l-ene-rich stream includes the steps of metathesizing the but-l-ene-rich stream at a temperature ranging from about 35 °C to about 120 °C and a pressure ranging from about 1 barg to about 20 barg using a rhenium oxide-coated y- alumina-based metathesis catalyst. In certain examples, metathesizing the but-l-ene-rich stream includes the steps of metathesizing the but-l-ene-rich stream at a temperature ranging from about 50 °C to about 120 °C and a pressure ranging from about 8 barg to about 20 barg. In certain examples, the but-l-ene-rich stream contains but-l-ene, but-2-enes, and 2-methylpropene. In certain examples, the method includes the steps of combining the hex-2-enes / hex-3-enes stream with the Ce olefin stream prior to Ce isomerization to produce the hex-l-ene-rich stream. In certain examples, the method includes the steps of combining at least a portion of the ethene product stream with the but-l-ene-rich stream prior to metathesis to produce the metathesis product stream.

[0011] In certain examples, performing Ce isomerization of the Ce olefin stream includes the steps of performing Ce isomerization of the Ce olefin stream at a temperature ranging from about 25 °C to about 500 °C and an operating pressure from about 1 barg to about 20 barg using a potassium oxide-coated y-alumina-based isomerization catalyst. In certain examples, performing C4 isomerization of the C4 olefin stream includes the steps of performing C4 isomerization of the C4 olefin stream at a temperature ranging from about 25 °C to about 500 °C and an operating pressure from about 1 barg to about 20 barg using a potassium oxide-coated y-alumina-based isomerization catalyst. In certain examples, the method includes the steps of responsive to receiving a C4 stream having a but-l-ene content less than 15 mol.%, performing C4 isomerization of the C4 stream to produce the but-l-ene-rich stream prior to metathesis; and responsive to the but-l-ene content of the C4 stream being greater than or equal to 15 mol.%, providing the C4 stream for metathesis as the but-l-ene-rich stream without performing C4 isomerization of the C4 stream. In certain examples, performing C4 isomerization of the C4 stream includes the steps of performing C4 isomerization of the C4 stream at a temperature ranging from about 25 °C to about 500 °C and an operating pressure from about 1 barg to about 20 barg using a potassium oxide-coated y-alumina- based isomerization catalyst.

[0012] In certain examples, the method includes the steps of extracting a C4 purge stream from the C4 olefin stream and extracting a Ce purge stream from the hex-l-ene-rich stream, the C4 purge stream containing C4 paraffins and C4 olefins, and the Ce purge stream containing Ce paraffins and Ce olefins. In certain examples, the method includes the steps of catalytically cracking the C5 olefin stream, the C4 purge stream, and the Ce purge stream to produce a cracked product stream substantially containing ethene and propene, and also containing hydrogen (H2) and other C1-9 hydrocarbons. In certain examples, catalytically cracking includes the steps of catalytically cracking the C5 olefin stream, the C4 purge stream, and the Ce purge stream the C4-C6 catalytic cracking reactor at a temperature ranging from about 450 °C to about 650 °C using a ZSM-5-based cracking catalyst.Brief Description of the Drawings

[0013] Examples will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals designate like structural elements or procedures in a method. Examples are illustrated by way of example and not by way of limitation in the accompanying drawings. The present disclosure can be better understood by referring to the following figures. These drawings illustrate the principles of the disclosure and no limitation of the scope of the disclosure is thereby intended.

[0014] FIG. 1 is a schematic representation of a system for producing hex-l-ene using isomerization of C4 olefins and metathesis, according to an example.

[0015] FIG. 2 is a schematic representation of a system for producing hex-l-ene using a recycle of Ce olefins, according to an example.

[0016] FIG. 3 is a schematic representation of a system for producing hex-l-ene, ethylene, and propylene using metathesis and Ce isomerization, and for producing additional ethene and propene using catalytic cracking of C4-C6 olefins, according to an example.

[0017] FIG. 4 is a flow diagram that illustrates a method for controlling aspects of the example of the system of FIG. 1, according to an example.

[0018] FIG. 5 is a schematic representation of a control system for controlling the systems associated with the production of hex-l-ene, according to an example.Detailed Description

[0019] So that the manner in which the features and advantages of the examples of the systems and methods disclosed herein, as well as others that will become apparent, may be understood inmore detail, a more particular description of examples of systems and methods briefly summarized above may be had by reference to the following detailed description of examples thereof, in which one or more are further illustrated in the appended drawings, which form a part of this specification. It is to be noted, however, that the drawings illustrate only various examples of the systems and methods disclosed herein and are therefore not to be considered limiting of the scope of the systems and methods disclosed herein as it may include other effective examples as well.

[0020] As used herein, the term “Cx-Cycompounds,” in which x and y are positive integer values, refers to hydrocarbon-based compounds, each compound containing between x and y carbon atoms, x and y inclusive. For example, a C3-C5 fraction refers to a mixture that substantially contains or entirely contains hydrocarbon-based compounds, each compound containing 3, 4, or 5 carbon atoms.

[0021] As used herein, the term “Cx+ compounds,” in which x is a positive integer value, refers to hydrocarbon-based compounds, each compound containing at least x carbon atoms. For example, a C3+ fraction refers to a mixture that substantially contains or entirely contains hydrocarbon-based compounds, each compound containing 3 or more (for example, 3, 4, 5, 6, and so forth) carbon atoms.

[0022] As used herein, the term “Cx- compounds,” in which x is a positive integer value, refers to hydrocarbon-based compounds, each compound containing no more than x carbon atoms. For example, a C4- fraction refers to a mixture that substantially contains or entirely contains hydrocarbon- based compounds, each compound containing 4, 3, 2, or 1 carbon atoms. It may be noted that, in certain cases, a “Cx- fraction” may also include hydrogen (H2), in addition to hydrocarbons having x or fewer carbon atoms.

[0023] The term “substantially contains” means that the mixture includes at least 50 mol.% of the named compound or class of compounds, such as at least 60 mol.%, at least 70 mol.%, at least 80 mol.%, at least 90 mol.%, at least 95 mol.%, at least 98 mol.%, at least 99 mol.%, or 100 mol.%, or any sub-ranges therebetween.

[0024] The term “but-2-enes” includes (Z)-but-2-ene (c / .s-but-2-ene), or (E)-but-2-ene ( / ra / ?.s-but- 2-ene), or combinations thereof. The term “pent-2-enes” includes (Z)-pent-2-ene, or (E)-pent-2- ene, or combinations thereof. The term “hex-2-enes” includes (Z)-hex-2-ene, or (£) -hex-2- ene, or combinations thereof. The term “hex-3-enes” includes (Z)-hex-3-ene, or (E)-hex-3-ene, or combinations thereof.

[0025] The terms “wt.%”, “vol. %”, or “mol.%” refers to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, that includes the component. In a non-limiting example, 10 grams of a component in 100 grams of the material is 10 wt.% of such component. As used herein, the term “enriched” or “rich” or their variations mean an amount of at least generally about 15 mol.%, and preferably about 20 mol.%, of a compound or class of compounds in a stream. As used herein, when a first component is described as receiving (or being configured to receive) a stream from a second component, or when a first component is described as providing (or being configured to provide) a stream to a second component, the first and second components may be alternatively described as being in fluid communication with one another. For the various streams discussed herein, a given stream substantially contains the compound or class of compounds in the name of the stream (for example, an ethene product stream substantially contains ethene, a C4 olefin stream substantially contains C4 olefins, a Ce olefin stream substantially contains Ce olefins), and the stream may also include other components.

[0026] The present disclosure describes various examples related to systems and method for producing hex-l-ene that involve metathesis of a C4 stream. The metathesis reactions discussed herein include both cross-metathesis and self-metathesis. Metathesis reactions discussed herein are generally equilibrium reactions, involving the recycling of C4 olefins back to the metathesis process after metathesis olefin product separation to increase the metathesis yields. The metathesis reactions utilize a metathesis catalyst, such as a rhenium oxide-coated y-alumina-based catalyst, which enables metathesis reactions at a temperature ranging from about 35 °C to 120 °C. Crossmetathesis and / or self-metathesis reactions of a but-l-ene-rich stream produce a metathesis product stream containing ethene, propene, and C4-C6 olefins. Examples of cross-metathesis reactions and self-metathesis reactions, as well as their respective equilibrium constants at different temperatures, are shown in Table 1.

[0027] Table 1. Example self-metathesis and cross-metathesis reactions.

[0028] FIG. 1 is a schematic representation of an example of a system 100 for producing at least propene and hex-l-ene. The system 100 includes a first C4 isomerization reactor 102 (also referred to herein as a pre-isomerization reactor) that is in fluid communication with a metathesis reactor 106. A C4 stream 101 containing but-l-ene and but-2-enes is supplied as the input stream to the system 100. Depending on the source of the C4 stream 101, the C4 stream 101 may have a but-l- ene content of less than 15 mol.%, such as from about 0 mol.% to about 13 mol.%. As the metathesis reactor 106 is configured to consume a but-l-ene-rich stream 104 having a but-l-ene content of at least 15 mol.%, when the C4 stream 101 has a but-l-ene content less than 15 mol.%,the C4 stream 101 may be conditionally directed to the first C4 isomerization reactor 102. In other examples, when the C4 stream 101 has a but-l-ene content greater than or equal to 15 mol.%, the first C4 isomerization reactor 102 may be omitted or skipped and the C4 stream 101 may be provided directly to the metathesis reactor 106 as the but-l-ene-rich stream 104. Regardless of whether the C4 stream 101 is isomerized to increase the but-l-ene content of the stream, the but-1-ene-rich stream 104 is provided to the metathesis reactor 106 without removing but-2-enes present within the stream. That is, Applicant recognized that the separation of but-l-ene from but-2-ene is an energy-intensive separation that typically requires fractionation. As such, the embodiments described herein are configured to function without requiring but-l-ene / but-2-ene separation via fractionation or requiring removal of substantially all of the but-2-ene from the but-1-ene-rich stream 104 prior to metathesis, which desirably reduces the installation and operational costs of the system, reduces the energy expenditure of the system, reduces the complexity of the system, and / or increases the throughput of the system.

[0029] For the example illustrated in FIG. 1, the first C4 isomerization reactor 102 isomerizes but-2-enes of the C4 stream 101 into but-l-ene to produce the but-l-ene-rich stream 104 having a but- l-ene content of at least 15 mol.%. For this C4 isomerization, the first C4 isomerization reactor 102 can operate at a temperature ranging from about 25 °C to about 500 °C and at a pressure ranging from about 1 barg to about 20 barg. For example, the first C4 isomerization reactor 102 can operate at a temperature of about 350 °C and at a pressure of 20 barg. The first C4 isomerization reactor 102 contains a C4 isomerization catalyst. In some examples, to reduce or prevent the buildup of unreactive C4 paraffins at the metathesis reactor 106, a first C4 purge stream 105 is extracted from the but-l-ene-rich stream 104, in which the first C4 purge stream 105 contains C4 paraffins (for example, butane, 2-methylpropane) and some C4 olefins. The first C4 purge stream 105 can be collected as a product or provided as a feed stream to another system or unit of a hydrocarbon processing facility outside of this configuration.

[0030] For the example illustrated in FIG. 1, the metathesis reactor 106 contains a metathesis catalyst that facilitates cross-metathesis and / or self-metathesis reactions of the but-l-ene-rich stream 104 to produce a metathesis product stream 108. In an example, the metathesis reactor 106 operates at a temperature about 60 °C and at a pressure about 20 barg. The metathesis product stream 108 contains ethene, propene, and C4-C6 olefins, as well as a limited amount of C4-C6paraffins. The flow rate of the but-l-ene-rich stream 104 can have a weight hourly space velocity (WHSV) ranging from about 0.1 per hour (h'1) to about 10 h'1.

[0031] In some examples, the metathesis catalyst is a rhenium oxide-coated y-alumina-based (Re2O7 / yA12O3) catalyst or an alumina-supported rhenium-based metathesis catalyst, also referred to as an egg-shell catalyst or a shaped metal-supported catalyst. The rhenium oxide-coated y- alumina-based catalyst can be spherical or an extrudate and may be described as having an eggshell structure. One such rhenium oxide-coated y-alumina-based catalyst has y-alumina-based spherical particles of a size ranging from about 1.2 mm to about 3 mm and a rhenium oxide coating ranging from about 150 pm to about 250 pm in thickness. Other examples include y-alumina-based extrudate particles of a size ranging from 1.2 mm to about 3 mm in diameter and from about 4 mm to about 8 mm in length, with the rhenium oxide coating ranging from about 150 pm to about 250 pm in thickness. In certain examples, the rhenium oxide-coated y-alumina-based catalyst contains rhenium oxide in an amount ranging from about 4.8 wt.% to about 5.6 wt.%. The rhenium oxidecoated y-alumina-based catalyst can facilitate conversion of one or more of: (trans / cis (t / c)) but-2- ene with but-l-ene to propene and (t / c) pent-2-ene, but-l-ene with but-l-ene to ethene and (t / c) hex-3-ene, ethene with (t / c) but-2-ene to propene and propene, but-l-ene with (t / c) pent-2-ene to propene and (t / c) hex-3-ene, and (t / c) pent-2-ene and (t / c) pent-2-ene to (t / c) but-2-ene and (t / c) hex-3 -ene in an operational metathesis reactor. In certain examples, the rhenium oxide-coated y- alumina-based catalyst can be functional for at least 300 days in the operational metathesis reactor. In certain examples, the catalyst is regenerated for greater than 50 times in the operational metathesis reactor. Based on regeneration times, the catalyst can be functional for about 1000 days or longer. These days can vary based on the weight hourly space velocity that may range from 0.6 hr'1to 10 hr'1.

[0032] Methods of preparing a rhenium oxide-coated y-alumina-based catalyst include the steps of calcining a y-alumina-based support to form a calcined y-alumina-based support at a temperature ranging from about 450 °C to about 550 °C and treating the calcined y-alumina-based support with an aqueous rhenium-containing mixture in a rotating drum impregnation unit to form a rhenium- coated y-alumina-based support. In certain examples, the aqueous rhenium-containing mixture is a NT ReC solution, an A 1( RcO-i) - solution, or a HReCU solution. In certain examples, the impregnation unit is rotated at a speed ranging from about 15 revolutions per minute (rpm) to about25 rpm to form a rhenium-coated y-alumina-based support. The method also includes the steps of aging the rhenium-coated y-alumina-based support to form a rhenium oxide-coated y-alumina- based catalyst after calcination, containing a rhenium oxide coating ranging from about 150 micrometers (pm) to about 250 pm in thickness, drying the rhenium-coated y-alumina-based catalyst immediately after aging, and calcining the rhenium-coated y-alumina-based catalyst at a temperature ranging from about 450 °C to about 550 °C to form rhenium oxide coated y-alumina. In certain examples, the step of aging the rhenium- coated y-alumina-based support is carried out for a time less than 5 minutes, thereby to form a rhenium oxide-coated y-alumina-based catalyst after calcination. In certain examples, the step of drying the rhenium- coated y-alumina-based catalyst immediately after aging at a temperature ranging from about 140 °C to about 160 °C.

[0033] The particle size of the y-alumina-based support can range from about 1.2 millimeters (mm) to about 3 mm. For example, the diameter of a spherical or a cylindrical y-alumina-based support can range from about 1.2 mm to about 3 mm. In certain examples, the y-alumina-based support has a pore volume ranging from about 0.5 milliliter per gram (ml / g) to about 0.65 ml / g. In certain examples, the y-alumina-based support has a pore diameter ranging from about 75 Angstroms (A) to about 110 A. In certain examples, the y-alumina-based support has a total acidity ranging from about 0.58 millimole per gram (mmolNH3 / g) to about 0.62 mmolNH3 / g. In certain examples, the rhenium oxide-coated y-alumina-based catalyst can contain rhenium oxide in an amount ranging from about 4.8 weight percent (wt.%) to about 5.6 wt.%. The rhenium oxide-coated y-alumina- based catalyst can have a surface area ranging from about 200 square meters per gram (m2 / g) to about 270 m2 / g. The rhenium oxide-coated y-alumina-based catalyst can be spherical in shape or an extrudate. An extrudate can be cylindrical or lobed or of other shapes. In certain examples, the rhenium particles of the coating have a particle size ranging from about 0.3 nanometer (nm) to about 1.2 nm.

[0034] Examples include methods of preparing an activated rhenium oxide-coated y-alumina- based catalyst. One such method includes the steps of treating the rhenium oxide-coated y-alumina- based catalyst under air at a temperature from about 500 °C to about 550 °C to produce an activated rhenium oxide-coated y-alumina-based catalyst, purging nitrogen into the activated rhenium oxi decoated y-alumina-based catalyst to displace the air, and cooling the activated rhenium oxide-coated y-alumina-based catalyst to a temperature of about 50 °C. In certain examples, the step of treatingthe rhenium oxide-coated y-alumina-based catalyst under air is carried out for about 6 hours to about 24 hours to produce an activated rhenium oxide-coated y-alumina-based catalyst. In certain examples, the step of treating the rhenium oxide-coated y-alumina-based catalyst under air is carried out for about 6 hours.

[0035] In some embodiments, the metathesis catalyst is a layered catalyst composition that contains an active layer and a base support. Examples of the base support are aluminum oxide, gallium oxide, silica oxide, zirconium oxide, niobium oxide, titanium oxide, lanthanum oxide, cerium oxide, or combinations thereof. The active layer of the catalyst contains an active metal component and an active support. The active metal component can be a Group 6, 7, 8, or 9 metal oxide. The active metal component can be one or more of a chromium, molybdenum, or tungsten compound. The active metal component can be one or more of a manganese, technetium, or rhenium compound. The active metal component can be one or more of iron, cobalt, nickel, ruthenium, rhodium, palladium, and platinum compound. Examples of the active metal component can be rhenium oxide or ruthenium oxide. Examples of the active support can be aluminum oxide, gallium oxide, silica oxide, zirconium oxide, niobium oxide, titanium oxide, lanthanum oxide, cerium oxide, or combinations thereof.

[0036] Certain examples of an olefin metathesis catalyst have a base support containing aluminum oxide and an active layer containing rhenium oxide as the active metal component and aluminum oxide as the active support. In certain examples, the acidic -OH groups of the active support are increased by incorporating about 0.5 % to 15 % of aluminum (or) zirconium precursor along with the rhenium precursor. The added aluminum (or) zirconium precursor (support precursor) along with the rhenium precursor produce an amorphous aluminum hydroxide or zirconium hydroxide with rhenium oxide. The amount of the metal component loaded in the active layer is reduced by at least about 10% to about 25% as compared to a rhenium oxide-alumina catalyst synthesized without aluminum / zirconium active support layer.

[0037] For the example illustrated in FIG. 1, the metathesis product stream 108 is supplied to a C3 column 110. The C3 column 110 can be a depropenizer. In some examples, the C3 column 110 can have from about 40 stages to about 60 stages. The C3 column 110 receives and separates the metathesis product stream 108 into a C2-C3 stream 140 and a C4+-rich stream 112. The C2-C3 stream 140 contains ethene and propene and the C4+-rich stream 112 contains the C4-C6 olefins.

[0038] For the example illustrated in FIG. 1, a C4 column 114 receives the C4+-rich stream 112 from the C3 column 110 for separation. The C4 column 114 can be a debutenizer. In some examples, the C4 column 114 can have from about 20 to about 40 stages. The C4 column 114 separates the C4+-rich stream 112 into a C4 olefin stream 134 and a Cs-Ce olefin stream 116.

[0039] For the example illustrated in FIG. 1, a second C4 isomerization reactor 136 receives the C4 olefin stream 134 from the C4 column 114. In some examples, to reduce or prevent the buildup of unreactive C4 paraffins at the metathesis reactor 106, a second C4 purge stream 135 is extracted from the C4 olefin stream 134, in which the second C4 purge stream 135 contains C4 paraffins (for example, butane, 2-methylpropane) and some C4 olefins. The second C4 purge stream 135 can be collected as a product or provided as a feed stream to another system or unit of a hydrocarbon processing facility outside of this configuration. The second C4 isomerization reactor 136 contains a C4 isomerization catalyst. The C4 isomerization catalyst can be a potassium oxide-coated y- alumina-based isomerization catalyst (for example, a K^O / y-alumina-based catalyst). During C4 isomerization, but-2-enes present within the C4 olefin stream 134 are isomerized in the second C4 isomerization reactor 136 to produce a butene recycle stream 138 that is enriched in but-l-ene, and the butene recycle stream 138 is supplied to the metathesis reactor 106. The metathesis reactor 106, C3 column 110, C4 column 114, and the second C4 isomerization reactor 136 constitute a C4 olefin recycle course of the system 100.

[0040] For the example illustrated in FIG. 1, a C2 / C3 splitter 142 receives the C2-C3 stream 140 from the C3 column 110. The C2 / C3 splitter 142 can be C2 / C3 distillation column. In some examples, the C2 / C3 splitter 142 can have from about 20 stages to about 40 stages. The C2 / C3 splitter 142 separates the C2-C3 stream 140 into two product streams, including an ethene-rich stream 144 (also referred to herein as an ethene product stream) and a propene-rich stream 146 (also referred to herein as a propene product stream). In some examples, at least a portion of the ethene-rich stream 144 is supplied to the metathesis reactor 106 as an ethene co-feed 148. For such examples, the recycle of at least a portion of the ethene-rich stream 144 as the ethene co-feed 148 to the metathesis reactor 106 can increase the production of the propene-rich stream 146. However, in certain examples, the ethene-rich stream 144 is desirably collected as a higher value olefin product stream, and the metathesis reaction proceeds in the absence of an ethene co-feed.

[0041] For the example illustrated in FIG. 1, a C5 column 118 receives the Cs-Ce olefin stream 116 from the C4 column 114. In some examples, the C5 column 118 is a depentenizer column. Incertain examples, the Cs column 118 has between 20 stages and 30 stages. The Cs column 118 separates the Cs-Ce olefin stream 116 into a Cs olefin product stream 120 containing pent-2-enes and a Ce olefin stream 122 containing hex-3 -enes.

[0042] For the example illustrated in FIG. 1, a Ce isomerization reactor 124 receives the Ce olefin stream 122 from the Cs column 118. The Ce isomerization reactor 124 contains a Ce isomerization catalyst, which may be the same as the C4 isomerization catalyst (for example, a K^O / y-alumina- based catalyst) in certain examples. Within the Ce isomerization reactor 124, hex-3-enes and hex- 2-enes of the Ce olefin stream 122 are isomerized into hex-l-ene to produce a hex-l-ene-rich stream 126. In certain examples, the Ce isomerization reactor 124 is operated at a temperature ranging from about 350 °C to about 500 °C and a pressure ranging from about 1 barg to about 20 barg. A Ce fractionator 128 receives the hex-l-ene-rich stream 126 from the Ce isomerization reactor 124. The Ce fractionator 128 can be a Ce fractionation column or a super fractionator. In some examples, the Ce fractionator 128 includes from about 150 stages to about 200 stages. The Ce fractionator 128 separates the hex-l-ene-rich stream 126 into a hex-l-ene product stream 130 and a hex-2-enes / hex-3-enes olefin stream 132. In some examples, the hex-l-ene product stream 130 has a hex-l-ene content of at least 99 mol.%. In some examples, a Ce purge stream 133 is extracted from the hex-l-ene-rich stream 126 by the Ce fractionator 128, in which the Ce purge stream 133 contains Ce paraffins (for example, hexanes) and a limited quantity of Ce olefins.

[0043] As noted above with respect to but-l-ene / but-2-ene separation, Applicant has recognized that fractionation is an energy-intensive separation process that requires a fractionation column to separate two or more species in a mixture that have relatively close boiling points. As such, for the embodiments described herein, fractionation is only used for separation of hex-l-ene from hex-2- enes and hex-3-enes in the Ce fractionator 128, while other separations of the metathesis product stream 108 are achieved using non-fractionating distillation columns (e.g., the C3 column 110, the C4 column 114, the Cs column 118, and the C2 / C3 splitter 142 for the embodiment illustrated in FIG. 1) Therefore, by avoiding the use of fractionation and fractionating columns, except for separation of the hexene species by the Ce fractionator 128, present embodiments desirably reduce the installation and operational costs, reduces the energy expenditure of the system, reduces the complexity of the system, and / or increases the throughput of the system.

[0044] In some examples, the hex-2-enes / hex-3-enes olefin stream 132 is recycled back to the Ce isomerization reactor 124 for further isomerization to increase the yield of hex-l-ene isolatedwithin the hex-l-ene product stream 130. In some examples, the Ce olefin stream 122, the hex-2- enes / hex-3-enes olefin stream 132, and / or the Cs olefin product stream 120 may be provided as input to a catalytic cracking system to primarily produce ethene and propene, along with H2 and C1-9 hydrocarbon byproducts. In some examples, the C5 olefin product stream 120 may be provided to the Ce isomerization reactor 124 or another suitable isomerization reactor (for example, a C5 isomerization reactor) to isomerize pent-2-enes to pent-l-ene, and the resulting mixture of pent-2- enes and pent-l-ene can then be separated (for example, by a C5 fractionator) to yield a pent-l-ene product stream.

[0045] FIG. 2 is a schematic representation of an example of a system 200 for producing at least propene and hex-l-ene. A but-l-ene-rich feed stream 202 having a but-l-ene content of at least 15 mol % is supplied to a metathesis reactor 204. In some cases, depending on the source of the but- l-ene-rich feed stream 202, the but-l-ene-rich feed stream 202 includes but-2-enes and a limited amount of 2-methylpropene. The metathesis reactor 204 contains a metathesis catalyst, as discussed above, that facilitates cross-metathesis and / or self-metathesis reactions of the but-l-ene- rich feed stream 202 to produce a metathesis product stream 206. The metathesis product stream 206 contains ethene, propene, and C4-C6 olefins.

[0046] For the example illustrated in FIG. 2, the metathesis product stream 206 is supplied to a C3 column 208 (for example, a depropenizer column). In some examples, the C3 column 208 has from about 40 stages to about 60 stages. The C3 column 208 separates the metathesis product stream 206 into a C2-C3 stream 240 that contains ethene and propene and a C4+-rich stream 212 that contains C4-C6 olefins. A C2 / C3 splitter 242 receives the C2-C3 stream 240 from the Cscolumn 208. The C2 / C3 splitter 242 can be a C2 / C3 distillation column. In some examples, the C2 / C3 splitter 242 has from about 20 stages to about 40 stages and operates at a pressure about 25 barg. The C2 / C3 splitter 242 separates the C2-C3 stream 240 into an ethene-rich stream 244 (for example, an ethene product stream) and a propene-rich stream 246 (for example, a propene product stream). In some examples, at least a portion of the ethene-rich stream 244 is supplied to the metathesis reactor 204 as an ethene co-feed 248. For such examples, the recycle of at least a portion of the ethene- rich stream 244 as the ethene co-feed 248 to the metathesis reactor 204 can increase the production of the propene-rich stream 246. However, in certain examples, the ethene-rich stream 244 is desirably collected as a higher value olefin product stream, and the metathesis reaction proceeds in the absence of an ethene co-feed.

[0047] For the example illustrated in FIG. 2, a C4 column 214 receives the C4+-rich stream 212 from the C3 column 208. The C4 column 214 can be a debutenizer column. In some examples, the C4 column 214 have from about 20 stages to about 40 stages. The C4 column 214 separates the C4+-rich stream 212 into a C4 olefin stream 234 and a C5-C6 olefin stream 216. In some examples, to reduce or prevent the buildup of unreactive C4 paraffins at the metathesis reactor 204, a C4 purge stream 235 is extracted from the C4 olefin stream 234, in which the C4 purge stream 235 contains C4 paraffins (for example, butane, 2-methylpropane) and a limited amount of C4 olefins. The C4 purge stream 235 can be collected as a product or provided as a feed stream to another system or unit of a hydrocarbon processing facility outside of this configuration.

[0048] For the example illustrated in FIG. 2, a C4 isomerization reactor 236 receives the C4 olefin stream 234 from the C4 column 214. The C4 isomerization reactor 236 contains an isomerization catalyst (for example, a K^O / y-alumina-based catalyst). During C4 isomerization, but-2-enes present within the C4 olefin stream 234 are isomerized in the C4 isomerization reactor 236 to produce a butene recycle stream 238 that is enriched in but-l-ene, and the butene recycle stream 238 is supplied to the metathesis reactor 204. The metathesis reactor 204, C3 column 208, C4 column 214, and C4 isomerization reactor 236 constitute a C4 olefin recycle course of the system 200.

[0049] For the example illustrated in FIG. 2, a C5 column 218 receives the C5-C6 olefin stream 216 from the C4 column 214. In some examples, the Cs column 218 is a depentenizer column. In certain examples, the C5 column 218 has from about 20 stages to about 40 stages and can operate at a pressure ranging from about 2 barg to about 5 barg. The C5 column 218 separates the Cs-Ce olefin stream 216 into a C5 olefin stream 220 containing pent-2-ene and a Ce olefin stream 222 containing hex-3-enes. The C5 olefin stream 220 can be supplied to a catalytic cracker, as discussed below, or can be collected as a product.

[0050] For the example illustrated in FIG. 2, the Ce olefin stream 222 is further processed through a hexene isomerization course to isomerize hex-3 -enes and hex-2-enes to hex-l-ene. The hexene isomerization course contains a Ce isomerization reactor 224. The Ce isomerization reactor 224 receives the Ce olefin stream 222 from the C5 column 218. The Ce isomerization reactor 224 contains an isomerization catalyst (for example, a K^CVy-alumina-based catalyst). During Ce isomerization, hex-2-enes and hex-3-enes in the Ce olefin stream 222 are isomerized into hex-l- ene to produce a hex-l-ene-rich stream 226. In certain examples, the Ce isomerization reactor 224can operate at a temperature ranging from about 350 °C to about 500 °C and a pressure ranging from about 1 barg to about 20 barg.

[0051] For the example illustrated in FIG. 2, the hexene isomerization course also contains a Ce fractionator 228. The Ce fractionator 228 receives the hex-l-ene-rich stream 226 from the Ce fractionator 228. The Ce fractionator 228 can be a Ce fractionation column or a super fractionator. In some examples, the Ce fractionator 228 includes from about 150 stages to about 200 stages and operates at pressures ranging from 1 barg to 20 barg. The Ce fractionator 228 separates the hex-l- ene-rich stream 226 into a hex-l-ene product stream 232 and a hex-2-enes / hex-3-enes stream 230. In some examples, the hex-l-ene product stream 232 has a hex-l-ene content of at least 99 mol.%. The hex-2-enes / hex-3-enes stream 230 is recycled back to the Ce isomerization reactor 224 for further isomerization to increase the yield of hex-l-ene isolated within the hex-l-ene product stream 232. In some embodiments, to reduce or prevent the buildup of unreactive Ce paraffins at the Ce isomerization reactor 224, a Ce purge stream 237 is removed from the hex-2-enes / hex-3- enes stream 230, in which the Ce purge stream 237 contains Ce paraffins (for example, hexanes) and a limited quantity of Ce olefins (for example, hex-2-enes, hex-3 -enes). The Ce purge stream 237 can be collected as a product or provided as a feed stream to another system or unit of a hydrocarbon processing facility outside of this configuration.

[0052] FIG. 3 is a schematic representation of an example of a system 300 for producing ethene, propene, and hex-l-ene, which involves catalytic cracking of Cs-Ce hydrocarbons to further enhance the production of ethene and propene. A but-l-ene-rich feed stream 302 having a but-1- ene content of at least 15 mol % is supplied to a metathesis reactor 304. In some cases, depending on the source of the but-l-ene-rich feed stream 302, the but-l-ene-rich feed stream 302 also includes but-2-enes and a limited amount of 2-methylpropene. The metathesis reactor 304 contains a metathesis catalyst, as discussed above, that facilitates cross-metathesis and / or self-metathesis reactions of the but-l-ene-rich feed stream 202 to produce a metathesis product stream 306. The metathesis product stream 306 contains ethene, propene, C4-C6 olefins, and a limited quantity of C4-C6 paraffins (for example, butane, 2-methylpropane, hexanes).

[0053] For the example illustrated in FIG. 3, the metathesis product stream 306 is supplied to a C3 column 308. The C3 column 308 can be a depropenizer. In some examples, the C3 column 308 has from about 40 stages to about 60 stages. The C3 column 308 separates the metathesis product stream 306 into a C2-C3 stream 342 that contains ethene and propene and a C4+-rich stream 310that contains the C4-C6 olefins. A C2 / C3 splitter 344 receives the C2-C3 stream 342 from the C3 column 308. The C2 / C3 splitter 344 can be C2 / C3 distillation column. In some examples, the C2 / C3 splitter 344 has from about 20 stages to about 40 stages and can operate at a pressure of about 25 barg. The C2 / C3 splitter 344 separates the C2-C3 stream 342 into two product streams, including an ethene-rich stream 346 (for example, an ethene product stream) and a propene-rich stream 348 (for example, a propene product stream).

[0054] For the example illustrated in FIG. 3, a C4 column 312 receives the C4+-rich stream 310 from the C3 column 308. The C4 column 312 can be a debutenizer column. In some examples, the C4 column 312 has from about 20 stages to about 40 stages. The C4 column 312 separates the C4+- rich stream 310 into a C4 olefin stream 330 and a C5-C6 olefin stream 313. In some examples, to reduce or prevent the buildup of unreactive C4 paraffins at the metathesis reactor 304, a C4 purge stream 331 is removed from the C4 olefin stream 330, in which the C4 purge stream 331 contains C4 paraffins (for example, butane, 2-methylpropane) and some C4 olefins. The C4 purge stream 331 is provided as an input stream for catalytic cracking, as discussed below.

[0055] For the example illustrated in FIG. 3, a C4 isomerization reactor 338 receives the C4 olefin stream 330 from the C4 column 312. The C4 isomerization reactor 338 contains an isomerization catalyst (for example, a K^O / y-alumina-based catalyst). During C4 isomerization, but-2-enes present within the C4 olefin stream 330 are isomerized in the C4 isomerization reactor 338 to produce a butene recycle stream 340 that is enriched in but-l-ene, and the butene recycle stream 340 is supplied to the metathesis reactor 304. The metathesis reactor 304, C3 column 308, C4 column 312, and C4 isomerization reactor 338 constitute a C4 olefin recycle course of the system 300.

[0056] For the example illustrated in FIG. 3, a C5 column 314 receives the C5-C6 olefin stream 313 from the C4 column 312. In some examples, the C5 column 314 is a depentenizer. In certain examples, the C5 column 314 has about 40 stages and can operate at a pressure of about 2 barg. The C5 column 314 separates the Cs-Ce olefin stream 313 into a C5 olefin stream 316 containing pent-2-enes and a Ce olefin stream 318 containing hex-3 -enes. The C5 olefin stream 316 is combined with the C4 purge stream 331 and provided as an input stream for catalytic cracking, as discussed below.

[0057] For the example illustrated in FIG. 3, the Ce olefin stream 318 is further processed through a hexene isomerization course to isomerize hex-3 -enes / hex-2-enes to hex-l-ene and to isolate ahex-l-ene product stream. The hexene isomerization course contains a Ce isomerization reactor 320. The Ce isomerization reactor 320 receives the Ce olefin stream 318 from the Cs column 314. The Ce isomerization reactor 320 contains an isomerization catalyst (for example, a K2O / y- alumina-based catalyst). During Ce isomerization, hex-2-enes and hex-3-enes in the Ce olefin stream 318 are isomerized into hex-l-ene to produce a hex-l-ene-rich stream 322. In certain examples, the Ce isomerization reactor 320 can operate at a temperature ranging from about 350 °C to about 500 °C and a pressure ranging from about 1 barg to about 20 barg.

[0058] For the example illustrated in FIG. 3, the hexene isomerization course also contains a Ce fractionator 329. The Ce fractionator 329 receives the hex-l-ene-rich stream 322 from the Ce isomerization reactor 320. The Ce fractionator 329 can be a Ce fractionation column or a super fractionator. The Ce fractionator 329 can be a Ce fractionation column or a super fractionator. In some examples, the Ce fractionator 329 includes from about 150 stages to about 200 stages and operates at pressures ranging from 1 barg to 20 barg. The Ce fractionator 330 separates the hex-l- ene-rich stream 322 into a hex-l-ene product stream 332 and a hex-2-enes / hex-3-enes olefin stream 336. In some examples, the hex-l-ene product stream 332 has a hex-l-ene content of at least 99 mol.%. The hex-2-enes / hex-3-enes olefin stream 336 is recycled back to the Ce isomerization reactor 320 for further isomerization to increase the yield of hex-l-ene isolated within the hex-l-ene product stream 332. In some examples, to reduce or prevent the buildup of unreactive Ce paraffins at the Ce isomerization reactor 320, a Ce purge stream 334 is removed from the Ce fractionator 329, in which the Ce purge stream 334 contains Ce paraffins (for example, hexanes) and a limited quantity of Ce olefins. The Ce purge stream 334 is combined with the C4 purge stream 331 and the C5 olefin stream 316 and provided as an input stream for catalytic cracking, as discussed below.

[0059] For the example illustrated in FIG. 3, the system 300 includes a catalytic cracking course that enables the production of additional C2-C3 olefins and other hydrocarbons relative to the examples discussed above. The catalytic cracking course contains a C4-C6 catalytic cracking reactor 324 having a ZSM-5-based cracking catalyst. The C4-C6 catalytic cracking reactor 324 can operate at a temperature ranging from about 450 °C to about 650 °C. The C4-C6 catalytic cracking reactor 324 receives the Ce purge stream 334, the C5 olefin stream 316, and the C4 purge stream 331. The C4-C6 hydrocarbons present within the received streams 334, 316, and 331 are cracked to produce a cracked product stream 328. The cracked product stream 328 includes additional C2-C olefins, H2, and C1-9 hydrocarbons. The cracked product stream 328 from the C4-C6 catalytic cracking reactor 324 may be provided to a steam cracker having a downstream separation section for further processing and separation to increase the production of the additional C2-C3 olefins, and to increase the ultimate production of ethene and propene for the system 300. In other examples, the system 200 of FIG. 2 or the system 300 of FIG. 3 may include the pre-isomerization reactor 102, as discussed with respect to FIG. 1.

[0060] FIG. 4 is a flow diagram of an example of a method 400 for controlling aspects of the example of the system 100 illustrated in FIG. 1. In certain examples, the method 400 may be stored within a memory of a controller and executed by a processor of the controller to control operation of the system 100.

[0061] For the example illustrated in FIG. 4A, the method 400 includes step 401, in which the controller determines the but-l-ene content of the input C4 stream 101. For example, in some examples, the C4 stream 101 traverses a feed analyzer that uses gas chromatography to determine the but-l-ene content of the C4 stream 101. At step 402, the controller determines whether the but- l-ene content of the input C4 stream 101 is less than a predetermined threshold value (for example, 15 mol.%). In response to determining that the but-l-ene content of the input C4 stream 101 is less than the predetermined threshold value, at step 403, the controller provides control signals to route the C4 stream 101 to the first C4 isomerization reactor 102, where the C4 stream 101 contacts the isomerization catalyst to isomerize but-2-enes of the C4 stream 101 into but-l-ene to yield the but- 1-ene-rich stream 104 having a but-l-ene content that is greater than or equal to the predetermined threshold value, and the but-l-ene-rich stream 104 is then directed to the metathesis reactor 106. In response to determining that the but-l-ene content of the input C4 stream 101 is greater than or equal to the predetermined threshold value, at step 404, the controller provides control signals to route the C4 stream 101 to the metathesis reactor 106 as the but-l-ene-rich stream 104 without first performing C4 isomerization.

[0062] FIG. 5 is a schematic representation of an example of a control system 500 for controlling the examples of the systems discussed above. The control system 500 includes at least one controller 502. Each controller 502 includes at least one processor 504, which can be or include a central processing unit (CPU), a graphics processing unit (GPU), a co-processing unit, a subprocessing unit, or any other suitable electronic data processor. Each controller 502 includes at least one memory 506, which can be or include random access memory (RAM), read-only memory(ROM), or any other suitable electronic memory or storage. For the example illustrated in FIG. 5, the controller 502 is communicatively connected to each of the units present in a particular implementation of the systems discussed above, such as the metathesis reactor 508, the C3 column 510, the C4 column 512, the C2 / C3 splitter 514, the C5 column 516, the C4 isomerization reactor 518, the Ce isomerization reactor 520, and the Ce fractionator 522. In certain examples, the C4-C6 catalytic cracking reactor 524 and the pre-isomerization reactor 526 can be communicatively connected to the controller 502. The controller 502 is further communicatively connected to certain other elements of the systems discussed above, such as a feed analyzer 530, as discussed above with respect to FIG. 4.

[0063] For the example illustrated in FIG. 5, the communicative connection between the controller 502 and the units and devices enables the controller 502 to receive monitoring and operational data from sensors and / or sub-controllers of each of these units or devices present in the examples discussed above, and further enables the controller 502 to provide control signals (for example, electrical signals, instructions, data packets) to modify the operation of each of these zones or devices. For example, the controller 502 can receive monitoring data from sensors (for example, temperature sensors, pressure sensors, and flow sensors) of each of these components, and based on predefined threshold values for certain operational parameters, can provide suitable control signals to modify the operation of one or more components of the metathesis-related units to ensure that the metathesis reactor 508 operates within the parameter ranges (for example, temperature ranges, pressure ranges, WHSV ranges, and so forth) discussed above. In certain examples, the controller 502 receives monitoring data from the feed analyzer 530 regarding the but-l-ene content of the input C4 stream 101 and provides suitable control signals to route the C4 stream 101 to the pre-isomerization reactor 526 or the metathesis reactor 508, depending on the but-l-ene content, as discussed above with respect to FIG. 4.Examples

[0064] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices and / or methods claimed herein are made and evaluated and, therefore, are intended to be purely exemplary and are not intended to limit the disclosure. There are numerous variations and combinations of reaction conditions, for example, component concentrations, desired solvents,solvent mixtures, temperatures, pressures and other reaction ranges and conditions that can be used to optimize the product purity and yield obtained from the described process.

[0065] Example 1:

[0066] In an example, the operational performance of the example of the system 100 illustrated in FIG. 1 was evaluated under certain illustrative operating conditions using a process simulation software, Aspen Plus® available from Aspen Technology Inc. of Bedford, Massachusetts, U.S.A. The operational performance of this system was simulated based on an example C4 stream 101 that is supplied to the pre-isomerization reactor 102 containing 2 wt.% but-l-ene, 73.4 wt.% but- 2-ene, 21.4 wt.% n-butane, 2.3 wt.% 2-methylpropane, 0.2 wt.% isobutylene, and 0.7 wt.% propane. Additionally, the operational performance of the system was modeled based on example metathesis reaction conditions for the metathesis reactor 106 having an operating temperature of 60 °C and an operating pressure of 8 barg, isomerization reaction conditions for the pre- isomerization reactor 102 having an operating temperature ranging from 350 °C to 500 °C and an operating pressure of 2 barg, the C4 isomerization reactor 136 having an operating temperature ranging from 350 °C to 500 °C and an operating pressure of 2 barg, the Ce isomerization reactor 124 having an operating temperature ranging from 350 °C to 500 °C and an operating pressure of 2 barg.

[0067] For the example of system 100 illustrated in FIG. 1, when the pre-metathesis isomerization reactor 202 is supplied with 18.024 ton per hour (ton / h) of the example C4 stream 101, simulation modeling indicates that the final products would be 0.114 ton / h of ethene, 4.883 ton / h of propene, and 1.436 ton / h of hex-l-ene. In addition, C4 paraffins and C4 olefins that are extracted from the but-l-ene-rich stream 104 and the C4 olefin stream 134 to form the C4 purge streams 105 and 135, respectively, and / or the Ce paraffins and Ce olefins that are extracted from the hex-l-ene-rich stream 126 to form the Ce purge stream 133, can also be collected and / or further processed to provide additional product streams (for example, C4 olefin product stream, a Ce olefin product stream, fuel streams), further increasing the yield of the system 100.

[0068] Example 2:

[0069] The operational performance of the example of the system 200 of FIG. 2 was simulated using modeling calculations based on the process simulation software, Aspen Plus®. The operational performance of this system was simulated based on an example but-l-ene-rich stream 202 that is provided as input to the metathesis reactor 204 containing 62.6 wt.% but-l-ene, 34.8wt.% but-2-ene, and 2.5 wt.% n-butane. Additionally, the operational performance of the system was modeled based on example metathesis reaction conditions for the metathesis reactor 204 having an operating temperature of 60 °C and an operating pressure of 12 barg, the C4 isomerization reactor 236 having an operating temperature of 350 °C and an operating pressure of 2 barg, and the Ce isomerization reactor 224 having an operating temperature of 400 °C and an operating pressure of 1 barg. Other operation performances of the system included a 40 stage C3 column 208 having an operating pressure of 25 barg, a 40-60 stage C4 column 214 having an operating pressure of 5 barg, a 20-40 stage C5 column 218 having an operating pressure of 2 barg, a 150-200 stage Ce fractionator 228 having an operating pressure of 1 barg, and a C2 / C3 splitter 242 having an operating pressure of 20-30 barg.

[0070] For the example of system 200 illustrated in FIG. 2, when supplied with 18.024 ton per hour (ton / h) of the example but- 1-ene- rich stream 202, simulation modeling indicated the products of the system would be 0.507 ton / h of ethene, 6.032 ton / h of propene, 3.061 ton / h of hex-l-ene, and 7.094 ton / h of pent-2-ene. In addition, C4 paraffins and C4 olefins that are extracted from the C4 olefin stream 234 to form the C4 purge stream 235, and / or the Ce paraffins and Ce olefins that are extracted from the hex-2-enes / hex-3-enes stream 230 to form the Ce purge stream 237, can also be collected and / or further processed to provide additional product streams (for example, C4 olefin product stream, a Ce olefin product stream, fuel streams), further increasing the yield of the system 200.

[0071] When ranges are disclosed herein, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, reference to values stated in ranges includes each and every value within that range, even though not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

[0072] Other objects, features and advantages of the disclosure will become apparent from the foregoing drawings, detailed description, and examples. These drawings, detailed description, and examples, while indicating specific examples of the disclosure, are given by way of illustration only and are not meant to be limiting. In further examples, features from specific examples maybe combined with features from other examples. For example, features from one example may be combined with features from any of the other examples. In further examples, additional features may be added to the specific examples described herein. It should be understood that although the disclosure contains certain aspects, examples, and optional features, modification, improvement, or variation of such aspects, examples, and optional features can be resorted to by those skilled in the art, and that such modification, improvement, or variation is considered to be within the scope of this disclosure.

Claims

Claims1. A hex-l-ene production system, comprising: a metathesis reactor configured to receive and metathesize a but-l-ene-rich stream having a but-l-ene content of at least 15 molar percent (mol.%) to produce a metathesis product stream containing ethene, propene, and C4-C6 olefins; a C3 column configured to receive and separate the metathesis product stream into a C2- C3 stream and a C4+-rich stream; a C2 / C3 splitter configured to receive and separate the C2-C3 stream into an ethene product stream and a propene product stream; a C4 column configured to receive and separate the C4+-rich stream into a C4 olefin stream and a Cs-Ce olefin stream; a C5 column configured to receive and separate the Cs-Ce olefin stream into a C5 olefin stream and a Ce olefin stream; a Ce isomerization reactor configured to receive and perform Ce isomerization of the Ce olefin stream to produce a hex-l-ene- rich stream, wherein hex-2-enes and hex-3-enes of the Ce olefin stream are converted into hex-l-ene during Ce isomerization; a C4 isomerization reactor configured to receive and perform C4 isomerization of the C4 olefin stream to produce a butene recycle stream that is provided to the metathesis reactor along with the but-l-ene-rich stream to produce the metathesis product stream, wherein but-2-enes of the C4 olefin stream are converted into but-l-ene during C4 isomerization; and a Ce fractionator configured to receive and separate the hex-l-ene-rich stream into a hex- l-ene product stream and a hex-2-enes / hex-3-enes stream.

2. The system of claim 1 , wherein the metathesis reactor is configured to operate at a temperature ranging from about 35 degrees Celsius (°C) to about 120 °C and a pressure ranging from about 1 barg to about 20 barg.

3. The system of claim 2, wherein the metathesis reactor is configured to operate at temperature ranging from about 50 °C to about 120 °C and a pressure ranging from about 8 barg to about 15 barg.

4. The system of any of claims 1-3, wherein the C3 column is configured to operate at a pressure ranging from about 5 barg to about 10 barg, the C2 / C3 splitter is configured to operate at a pressure of about 25 barg, the C4 column is configured to operate at a pressure ranging from about 2 barg to about 8 barg, the C5 column is configured operate at a pressure ranging from about 2 barg to about 5 barg, and the Ce fractionator is configured to operate at a pressure ranging from 1 barg to 20 barg.

5. The system of any of claims 1-4, wherein the hex-2-enes / hex-3-enes stream is recycled to the Ce isomerization reactor for Ce isomerization to produce the hex- 1 -ene-rich stream.

6. The system of any of claims 1-5, wherein at least a portion of the ethene product stream is supplied to the metathesis reactor as a co-feed.

7. The system of any of claims 1-6, wherein the metathesis reactor includes a rhenium oxide-coated y-alumina-based metathesis catalyst, and the C4 isomerization reactor and the Ce isomerization reactor include a potassium oxide-coated y-alumina-based isomerization catalyst.

8. A method for producing hex-1 -ene, the method comprising: metathesizing a but- 1 -ene-rich stream having a but- 1 -ene content of at least 15 molar percent (mol.%) to produce a metathesis product stream containing ethene, propene, and C4-C6 olefins; separating the metathesis product stream into a C2-C3 stream and a C4+-rich stream; separating the C2-C3 stream into an ethene product stream and a propene product stream; separating the C4+-rich stream into a C4 olefin stream and a Cs-Ce olefin stream; separating the Cs-Ce olefin stream into a C5 olefin stream and a Ce olefin stream; performing Ce isomerization of the Ce olefin stream to produce a hex- 1 -ene-rich stream, wherein hex-2-enes and hex-3 -enes of the Ce olefin stream are converted into hex-1- ene during Ce isomerization;performing C4 isomerization of the C4 olefin stream to produce a butene recycle stream that is combined with the but- 1-ene- rich stream prior to metathesis, wherein but-2- enes of the C4 olefin stream are converted into but-l-ene during C4 isomerization; and separating the hex-l-ene-rich stream into a hex-l-ene product stream and a hex-2- enes / hex-3-enes stream.

9. The method of claim 8, wherein metathesizing the but-l-ene- rich stream comprises: metathesizing the but- 1 -ene-rich stream at a temperature ranging from about 35 degreesCelsius (°C) to about 120 °C and a pressure ranging from about 1 barg to about 20 barg using a rhenium oxide-coated y-alumina-based metathesis catalyst.

10. The method of any of claims 8-9, further comprising: combining the hex-2-enes / hex-3-enes stream with the Ce olefin stream prior to Ce isomerization to produce the hex-l-ene-rich stream.

11. The method of any of claims 8-10, further comprising: combining at least a portion of the ethene product stream with the but- 1 -ene-rich stream prior to metathesis to produce the metathesis product stream.

12. The method of any of claims 8-11, further comprising: responsive to receiving a C4 stream having a but-l-ene content less than 15 mol.%, performing C4 isomerization of the C4 stream to produce the but- 1 -ene-rich stream prior to metathesis; and responsive to the but-l-ene content of the C4 stream being greater than or equal to 15 mol.%, providing the C4 stream for metathesis as the but- 1 -ene-rich stream without performing C4 isomerization of the C4 stream.

13. The method of claim 8, wherein performing C4 isomerization of the C4 stream comprises: performing C4 isomerization of the C4 stream at a temperature ranging from about 25 °C to about 500 °C and an operating pressure from about 1 barg to about 20 barg using a potassium oxide-coated y-alumina-based isomerization catalyst.

14. The method of claim 8, further comprising: extracting a C4 purge stream from the C4 olefin stream and extracting a Ce purge stream from the hex-l-ene-rich stream, the C4 purge stream containing C4 paraffins and C4 olefins, and the Ce purge stream containing Ce paraffins and Ce olefins.

15. The method of claim 14, further comprising: catalytically cracking the C5 olefin stream, the C4 purge stream, and the Ce purge stream to produce a cracked product stream substantially containing ethene and propene, and also containing hydrogen (H2) and other C1-9 hydrocarbons.

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