Systems and methods of producing HEX-1-ENE, ethene, and propene using low-temperature metathesis

Abstract

Provided here systems and methods for the production of hex-1-ene, ethene, and propene using low- temperature metathesis operation conditions. Methods for the production of hex-1-ene, ethene, and propene include absorbing one or more contaminants from a C4 feed stream to output a pretreated C4 stream containing less than 15 mol. % of but-1-ene. The method further includes isomerizing the pretreated C4 stream to produce an isomerized C4 stream, and separating the isomerized C4 stream to produce a but-1-ene-rich stream. The method further includes metathesizing the but-1-ene-rich stream at temperatures ranging from about 35 ºC to about 100 ºC to produce a metathesis product stream. The method further includes separating the metathesis product stream to produce (i) a C2 / C3 product stream containing ethene and propene and (ii) a C4+ olefins stream that is further processed to obtain hex-1-ene. The method also includes splitting the C2 / C3 product stream to produce an ethene product stream and a propene product stream.

Description

SYSTEMS AND METHODS OF PRODUCING HEX-l-ENE, ETHENE, AND PROPENE USING LOW-TEMPERATURE METATHESISCross-Reference to Related Applications

[0001] This application claims priority to and the benefit of European Application No. EP24153802.4, filed on January 24, 2024. The contents of the referenced application are incorporated into the present application by reference.Technical Field

[0002] The disclosure relates to the production of hex-l-ene, ethene, and propene using C4 isomerization, C4 fractionation, and low-temperature metathesis.Background

[0003] Steam cracking processes are used to produce ethene, propene, and C4 olefins, such as but- 1-ene, but-2-ene, isobutene, butyne, and butadiene. With the abundance of United States (U.S.) shale gas, steam crackers have shifted towards using lighter feedstocks, which drop the production of propene. As the demand for propene increases, there exists an opportunity to increase the production of propene using alternative processes for the production of propene while producing other olefins such as hex-l-ene.Summary

[0004] Applicant has identified a need for the conversion of C4 olefins to hex-l-ene, ethene, and propene using low-temperature metathesis without the use of ethene as a co-feed. 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 embodiments of systems for the production of hex-l-ene, ethene, and propene and methods for producing hex-l-ene, ethene, and propene using low-temperature metathesis.

[0005] Examples include an olefin production system for producing hex-l-ene, ethene, and propene. The system includes a feed pre-treater configured to receive a C4 feed stream and output a pretreated C4 stream. The system further includes a C4 isomerization reactor containing a BUO / y- AhCh-based catalyst in fluid communication with the feed pre-treater and configured to receive the C4 feed stream and produce an isomerized C4 stream, which is rich in but-l-ene. The system further includes a C4 fractionator in fluid communication with the C4 isomerization fixed bed reactor and is configured to receive the isomerized C4 stream and produce (i) a but-l-ene-rich stream containing unreacted but-2-ene, (ii) a butane-rich stream, and (iii) a but-2-ene-rich stream received by the C4isomerization reactor. In certain examples, the but-l-ene-rich stream can contain about 15 molar percent (mol. %) of but-l-ene to about 60 mol. % of but-l-ene. In certain examples, the but-l-ene- rich stream contains greater than or equal to 90 mol. % of but-l-ene. The system further includes a metathesis reactor containing a rhenium oxide-coated y-alumina-based catalyst in fluid communication with the C4 fractionator and is configured to receive the but-l-ene-rich stream and produce a metathesis product stream containing ethene, propene, Cs-Ce olefins, and unreacted but-l- ene and but-2-ene. In some examples, the metathesis reactor is a fixed bed reactor. The metathesis reactor operates at temperatures ranging from about 35 °C to about 100 °C. The system further includes a C3 column in fluid communication with the metathesis reactor and is configured to receive the metathesis product stream and produce (i) a C2 / C3 product stream containing ethene and propene and (ii) a C4+ olefins stream containing Cs-Ce olefins and unreacted but-l-ene and but-2-ene. The system further includes a C4 column in fluid communication with the C3 column and is configured to receive the C4+ olefins stream and produce (i) a C4 recycle stream containing pent-2-ene and unreacted but-l-ene and but-2-ene and (ii) Cs-Ce olefins stream. The C4 recycle stream is supplied to the metathesis reactor. The system further includes a C2 / C3 splitter column in fluid communication with the C3 column and is configured to receive the C2 / C3 product stream and produce an ethene product stream and a propene product stream. In certain examples, the system can further include a Ce isomerization reactor containing K^O / y-AhCh-based catalyst in fluid communication with the C4 column and is configured to receive the Cs-Ce olefins stream and produce a hex-3 -ene-ri ch stream containing hex-3-ene, hex-2-ene, and hex-l-ene. The Ce isomerization reactor can operate at temperatures ranging from about 250 °C to about 500 °C. A Ce fractionator can be in fluid communication with the Ce isomerization reactor and configured to receive the hex-3 -ene-ri ch stream and can produce (i) a substantially pure hex-l-ene stream and (ii) a hex-2-ene-rich stream containing hex-2-ene and unconverted hex-3-ene. The hex-2-ene-rich stream can be recycled to the Ce isomerization reactor.

[0006] In certain examples, the C4 column in fluid communication with the C3 column is configured to receive the C4+ olefins stream and produce (i) a C4 recycle stream containing unreacted but-l-ene and but-2-ene and (ii) Cs-Ce olefins stream containing Ce olefins. The system can further include a Cs column in fluid communication with the C4 column and configured to receive the Cs-Ce olefins stream and produce a Cs olefins stream and a Ce olefins stream. A second metathesis reactor containing the rhenium oxide-coated y-alumina-based catalyst can be in fluid communication withthe Cs column and can be configured to receive the C5 olefins stream and the ethene product stream and produce a second propene product stream and a but-l-ene product stream. The second metathesis reactor can operate at temperatures ranging from about 35 °C to about 100 °C and at pressures ranging from about 0 bar gauge (barg) to about 30 barg.

[0007] In another example, an olefin production system includes a feed pre-treater configured to receive a C4 feed stream and output a pretreated C4 stream. The system further includes a C4 isomerization reactor containing a K^O / y-AhCh-based catalyst in fluid communication with the feed pre-treater and is configured to receive the C4 feed stream and produce an isomerized C4 stream, which is rich in but-l-ene. The system further includes a C4 fractionator in fluid communication with the C4 isomerization reactor and is configured to receive the isomerized C4 stream and produce (i) a but-l-ene stream containing unreacted but-2-ene, (ii) a butane-rich stream containing butane, and (iii) the but-2-ene-rich recycle stream that is supplied to the C4 isomerization reactor. The system further includes a metathesis reactor containing a rhenium oxide-coated y-alumina-based catalyst in fluid communication with the C4 fractionator and is configured to receive the but-l-ene-rich stream and produce a metathesis product stream containing ethene, propene, and Cs-Ce olefins, and unconverted but-l-ene and but-2-ene. In certain examples, the but-l-ene-rich stream contains about 15 mol. % of but-l-ene. In certain examples, the but-l-ene-rich stream contains greater than 15 mol. % of but-l- ene to about 60 mol. % of but-l-ene. In certain examples, the but-l-ene-rich stream contains greater than or equal to 90 mol. % of but-l-ene. The metathesis reactor operates at temperatures ranging from about 35 °C to about 100 °C. The system further includes a C3 column in fluid communication with the metathesis reactor and is configured to receive the metathesis product stream and produce (i) a C2 / C3 product stream containing ethene and propene and (ii) a C4+ olefins stream containing but-l- ene, Cs-Ce olefins, and unreacted but-2-ene. The system further includes a Cs column in fluid communication with the C3 column and is configured to receive the C4+ olefins stream and produce (i) C4-C5 recycle stream containing the unreacted but-l-ene and Cs olefins and (ii) a Ce olefins stream containing Ce olefins. The C4-C5 recycle stream is supplied to the metathesis reactor. The system further includes a C2 / C3 splitter column in fluid communication with the C3 column and can be configured to receive the C2 / C3 product stream and produce an ethene product stream and a propene product stream. In certain examples, the system can further include a Ce isomerization reactor containing K^O / y-AhCh-based catalyst in fluid communication with the Cs column and can be configured to receive the Ce olefins stream and produce a hex-l-ene-rich stream containing hex-3-ene, hex-2-ene, and hex-l-ene. The Ce isomerization reactor can operate at temperatures ranging from about 250 °C to about 500 °C. The system can further include a Ce fractionator in fluid communication with the Ce isomerization reactor and can be configured to receive the hex-3 -ene-ri ch stream and produce (i) a substantially pure hex-l-ene stream and (ii) a hex-2-ene-rich stream containing hex-2- ene and hex-3-ene that is optionally recycled to the Ce isomerization reactor.

[0008] In certain examples, the ethene product stream can be recycled to the metathesis reactor. In certain examples, the metathesis reactor can be fluid communication with the feed pre-treater and can be configured to receive any but- 1 -ene-ri ch stream containing about or greater than 15 mol. % of but- 1-ene. In certain examples, the C4+ olefins stream can contain greater than or equal to 15 mol. % of but-l-ene. In certain examples, the pretreated C4 stream contains less than 15 mol. % of but-l-ene.

[0009] Methods for producing olefins such as hex-l-ene, ethene, and propene include the step of absorbing one or more contaminants from a C4 feed stream to output a pretreated C4 stream containing less than 15 mol. % of but-l-ene. The method further includes the step of isomerizing the pretreated C4 stream to produce an isomerized C4 stream. The method further includes the step of separating the isomerized C4 stream to produce (i) a but- 1 -ene-ri ch stream containing unreacted but-2-ene and (ii) a butane-rich stream. The but-2-ene stream is isomerized into a but- 1 -ene-ri ch stream. The method further includes the step of metathesizing the but- 1 -ene-ri ch stream at temperatures ranging from about 35 °C to about 100 °C to produce a metathesis product stream. The method further includes the step of separating the metathesis product stream to produce (i) a C2 / C3 product stream containing ethene and propene and (ii) a C4+ olefins stream containing Cs-Ce olefins, and unreacted but-l-ene. The method further includes the step of splitting the C2 / C3 product stream to produce an ethene product stream and a propene product stream. In certain examples, the method can further include the step of separating the C4+ olefins stream to produce (i) a C4+ recycle stream containing the unreacted but-l-ene and Cs olefins (ii) a Ce olefins stream containing hex-3 -ene. The method further includes the step of supplying the C4+ recycle stream to be metathesized into the metathesis product stream. In certain examples, the method can further include the steps of isomerizing the Ce olefins to produce a hex- 1 -ene-ri ch stream containing hex-3 -ene, hex-2-ene, and hex-l-ene, followed by separating the hex- 1 -ene-ri ch stream to produce a substantially pure hex-l-ene stream and a hex-2-ene-rich stream containing hex-2-ene and unconverted hex-3-ene. In certain examples, the hex-2-ene-rich stream is subjected to isomerization to produce a hex- 1 -ene-ri ch stream.

[0010] In certain examples, the method can further include the step of supplying the ethene product stream to be metathesized into the metathesis product stream. In certain examples, the method canfurther include the step of separating the C4+ olefins stream to produce (i) a C4 recycle stream containing unreacted but-l-ene and but-2-ene and (ii) Cs-Ce olefins stream, followed by the step of separating the Cs-Ce olefins stream to produce a C5 olefins stream and a Ce olefins stream. The method can also further include the step of metathesizing the C5 olefins stream to produce a second propene product stream and a but-l-ene product stream.Brief Description of the Drawings

[0011] Embodiments 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. Embodiments 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.

[0012] FIG. 1 is a schematic representation of a system for the production of hex-l-ene and ethene using isomerization of Ce olefins and a butene feed stream that contains greater than or equal to 15 mol. % of but-l-ene, according to an example.

[0013] FIG. 2 is a schematic representation of a system for the production of Ce olefins and ethene using a butene feed stream that contains greater than or equal to 15 mol. % of but-l-ene, according to an example.

[0014] FIG. 3 is a schematic representation of a system for the production of hex-l-ene, ethene, and propene using a butene feed stream that contains less than 15 mol. % of but-l-ene, according to an example.

[0015] FIG. 4 is a schematic representation of a system for the production of Ce olefins, ethene, and propene using a Cs olefins recycle and a butene feed stream that contains less than 15 mol. % of but-l-ene, according to an example.

[0016] FIG. 5 is a schematic representation of a system for the production of hex-l-ene and propene using isomerization of Ce olefins, a butene feed stream that contains less than 15 mol. % of but-l-ene, and a Cs olefins recycle to increase the production of hex-l-ene and propene, according to an example.

[0017] FIG. 6 is a schematic representation of a system for the production of hex-l-ene and propene using isomerization of Ce olefins, a butene feed stream that contains less than 15 mol. % ofbut-l-ene, and a partial recycle of ethene to increase the production of hex-l-ene and propene, according to an example.

[0018] FIG. 7 is a schematic representation of a system for the production of hex-l-ene and propene using a butene feed stream that contains less than 15 mol. % of but-l-ene and two metathesis reactors to increase the production of hex-l-ene and propene, according to an example.

[0019] FIG. 8 is a schematic representation of a control system for controlling the systems associated with the production of hex-l-ene, ethene, propene, Cs olefins, and Ce olefins, according to an example.Detailed Description

[0020] 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 in more 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.

[0021] The description may use the phrases “in some embodiments,” “in various embodiments,” “in an embodiment,” or “in certain embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present disclosure, are synonymous.

[0022] The term “about” refers to a range of values including the specified value, which a person of ordinary skill in the art would consider reasonably similar to the specified value. In embodiments, “about” refers to values within a standard deviation using measurements generally acceptable in the art. In one non-limiting embodiment, when the term “about” is used with a particular value, then “about” refers to a range extending to ±10% of the specified value, alternatively ±5% of the specified value, or alternatively ±1% of the specified value, or alternatively ±0.5% of the specified value. In embodiments, “about” refers to the specified value.

[0023] The terms “reducing,” “reduced,” or any variation thereof, when used in the claims and / or the specification includes any measurable decrease or complete removal to achieve a desired result.

[0024] The use of the words “a” or “an” when used in conjunction with any of the terms “comprising,” “including,” “containing,” or “having,” in the claims or the specification may mean“one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” 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. The terms “enriched” or “rich” or their variations mean an amount of at least generally about 13 mol. %, and preferably about 15 mol. %, of a compound or class of compounds in a stream. The term “ppmw” refers to part per million by weight.

[0025] Hydrocarbon molecules may be abbreviated Ci, C2, C3 . Cn where “n” represents the number of carbon atoms in the one or more hydrocarbon molecules. Furthermore, a superscript “+” or or the terms “plus” and “minus” may be used with an abbreviated one or more hydrocarbons notation, e.g., C3+ or C3-, which is inclusive of the abbreviated one or more hydrocarbons. As an example, the term C3+ means one or more hydrocarbon molecules of three carbon atoms and / or more.

[0026] 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.

[0027] 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 (e.g., 3, 4, 5, 6, and so forth) carbon atoms.

[0028] 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 hydrocarbonbased 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.

[0029] The term “substantially contains” means that the mixture includes at least 60%, or even at least 70%, or even at least 80% by weight of the relevant hydrocarbon-based compounds.

[0030] As used herein, the term “zone” can refer to an area including one or more units and / or one or more sub-zones. Units can include one or more reactors or reactor vessels, separators, strippers, extraction columns, fractionation columns, heaters, exchangers, pipes, pumps, valves, compressors, sensors, and controllers. Additionally, a unit, such as a reactor, dryer, or vessel, can further includeone or more zones or sub-zones that contain various equipment. As used herein, the term “LPG” refers to liquified petroleum gas, and the term “NGL” refers to natural gas liquids.

[0031] 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. It may be appreciated that, for the various streams discussed herein, a given stream predominantly contains the compound or class of compounds in the name of the stream (e.g., an ethene stream predominantly contains ethene, a C4 olefins stream predominantly contains C4 olefins, a Ce olefins stream predominantly contains Ce olefins), and the stream may also include other components. As used herein, the term “predominantly contains” refers to a stream containing 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.

[0032] Steam cracking processes are used to produce ethene as a major product along with the other side products, such as propene and C4 species, such as but-l-ene, but-2-ene, 2-methylprop-l- ene, butynes, buta- 1,3 -diene, and so forth. In recent years, there has been a dramatic increase in the demand for propene to feed the growing markets for polypropylene, propylene oxide, and acrylic acid. Currently, about 85% of propene on the market is produced as the by-product of steam cracking of hydrocarbons (e.g., propane, NGL, naphtha) and fluid catalytic cracking (FCC) processes in refineries. Due to the recent abundance of shale gas in the U.S., there has been a shift towards lighter feedstocks in steam crackers. This is expected to cause a drop in propene as a byproduct from steam crackers. Also, due to the anticipated dip in gasoline demand, the FCC route to producing propene is also expected to be impacted. As a result, there will arise a gap between demand and supply of propene. In this context, intentional propene production routes are expected to see a revival. These intentional propene production routes include methanol to olefins / propene, propane dehydrogenation, and olefin metathesis. Metathesis offers a desirable route for valorization of low value olefins, like C4 and C5 olefins, into high value propene product. In certain existing metathesis methods and systems referred to as olefin conversion technology (OCT), ethene is often supplied as a co-feed to metathesis reactors. However, it is presently recognized that OCT has drawbacks, including the use of higher value ethene to produce propene, the selective uses of but-l-ene for metathesis, relatively high carbondioxide (CO2) production, and relatively high metathesis reaction temperatures (e.g., from 250 °C to 450 °C).

[0033] The present disclosure describes various examples related to systems for the production of hex-l-ene, C5 olefins, Ce olefins, ethene, and propene and methods for producing hex-l-ene, C5 olefins, Ce olefins, ethene, and propene. Recognizing that metathesis reactions typically occur at high temperatures that expend high energy, the present disclosure relates to methods and systems for the metathesis of C4 olefins at low reaction temperature i.e., 35-100 °C, to produce high value product ethene, propene, C5 olefins, and Ce olefins. The production of the products is based on the market demand or based on the end value product demand. The present disclosure uses a C4 feed stream that is pretreated and metathesized at low temperatures to improve olefin production. Ethene is substantially absent as a co-feed. The C4 olefins and C5 olefins can be but-l-ene, (Z)-but-2-ene I (E)- but-2-ene, and pent-2-ene. The metathesis reactions can be either of self-metathesis or cross-type metathesis. In self-metathesis, two molecules of one reactant are converted to form two products, while with cross-type metathesis, two different products are reacted and converted into two products. The present disclosure uses self-metathesis, cross-type metathesis, or combination of both metathesis reactions depending on the required product.

[0034] In one or more examples, the system includes a feed pre-treater. The feed pre-treater receives a C4 feed stream or C4 raffinate stream containing but-l-ene, but-2-ene, / / -butene, / / -butane, / -butane, 2-methylpropene ( / -butylene), propane, trace components of butynes (<5 ppm), and butadiene (< 30 ppm). The C4 feed stream can also contain allowable range of oxygenates such as MTBE, methanol etc. The composition of the C4 feedstock can depend on its source, including gas / liquid / light crude / crude oil cut mixed steam cracker downstream of a MTBE reactor, a but-l-ene (Bl) column, a but-2-ene (B2) column, a butadiene hydrogenation reactor, an MTO (methanol-to- olefins) process or refinery, and / or an FCC downstream process. As non-limiting examples, sample compositions of two different C4 feed stream are provided in Table 1, shown below.

[0035] Table 1: Sample C4 feed stream compositions

[0036] The feed pre-treater is configured to absorb one or more components from the C4 feedstock. The one or more components include a sulfur compound, an alcohol compound, oxygenates, or a combination thereof. The feed pre-treater removes one or more components based on the content percentage of the one or more components. In certain examples, the feed pre-treater is a single guard bed or dual guard beds or multiple guard beds. After the one or more components are absorbed in the feed pre-treater, the feed pre-treater outputs a pretreated C4 stream.

[0037] The system further includes a C4 isomerization reactor. The C4 isomerization reactor is in fluid communication with the feed pre-treater and is configured to receive the pretreated C4 stream. The C4 isomerization reactor isomerizes the c / .s-but-2-ene and / ra / / .s-but-2-ene to but-l-ene. An isomerized C4 stream is produced. In certain examples, the isomerized C4 stream contains greater than 15 mol. % of but-l-ene at temperatures of about 350 degrees Celsius (°C) to about 400 °C. The isomerized C4 stream contains but-l-ene, butane, and trace amounts of but-2-ene. The C4 isomerization reactor can be operated at temperatures ranging from about 250 °C to 550 °C and contain proprietary catalysts such as, K2O / Y-AI2O3. The C4 isomerization reactor can be operated to receive a liquid feed, vapor feed or mixed phase feed. The C4 isomerization reactor can operate at pressures ranging from about 0 bar gauge (barg) to 100 barg. However, it is noted that the isomerization reaction is pressure independent, and the process can generally be performed at a pressure that best suits the upstream and downstream operations. The C4 isomerization reactor can also be a traditional packed bed reactor or a moving bed reactor. The C4 isomerization reactor contains K^O / y-AhCh-based isomerization catalyst.

[0038] The C4 isomerization reactor can have an operating cycle time ranging from about 1 days to about 100 days. The C4 isomerization reactor can have a weight hourly space velocity (WHSV) ranging from about 0.1 h'1to 25 h'1. For example, the WHSV can be from about 0.5 h'1to 10 h'1.Regeneration of isomerization reactor can be performed using nitrogen, air, enriched air, or oxygen at temperatures ranging from about 300 °C to about 600 °C. In certain examples, the system can include two or more C4 isomerization reactors with at least one C4 isomerization reactor being in service while the remaining C4 isomerization reactors are in regeneration mode or on standby. The components of an isomerized C4 stream are shown in Table 2 below.

[0039] The system includes a C4 fractionator. In certain examples, the C4 fractionator can be a super fractionator or conventional fractionator. The C4 fractionator is in fluid communication with the C4 isomerization reactor and is configured to receive the isomerized C4 stream. The C4 fractionator separates the C4 isomerization stream into a but-l-ene stream that contains unreacted but-2-ene, a butane-rich stream that contains butane, and a but-2-ene-rich stream.

[0040] The system further includes a metathesis reactor. The metathesis reactor is in fluid communication with C4 fractionator and is configured to receive the but-l-ene-rich stream. In some examples, the metathesis reactor is in fluid communication with the feed pre-treater and configured to receive the pretreated C4 stream, in the instances when the C4 stream has greater than or about 15 mol. % of but-l-ene. The metathesis reactor can operate at temperatures from about 35 °C to about 100 °C.

[0041] To facilitate the metathesis reactions in the metathesis reactor, a metathesis catalyst, such as a rhenium oxide-coated y-alumina-based catalyst, is provided in the metathesis reactor. The rhenium oxide-coated y-alumina-based catalyst (Re2O7 / yAhO3) can be spherical or an extrudate. 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 oxide-coated 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 least300 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 to 10 / hr.

[0042] 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 Celsius (°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 NFUReCh solution, an Al(ReO4)3 solution, or a HReCh solution. In certain examples, the impregnation unit is rotated at a speed ranging from about 15 revolutions per minute (rpm) to about 25 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 conducted 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 occurs at a temperature ranging from about 140 °C to about 160 °C.

[0043] 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 (mmolxm / g) to about 0.62 mmolNm / 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 asurface 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.

[0044] 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 oxidecoated 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 treating the rhenium oxide-coated y-alumina-based catalyst under air is conducted for about 4 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 conducted for about 6 hours.

[0045] The rhenium oxide-coated y-alumina-based catalyst is used for self and cross metathesis of but-l-ene and (t / c) but-2-ene, in some examples.

[0046] The metathesis reactor produce a metathesis product stream that contains ethene, propene, but-l-ene, unreacted but-2-ene, and Cs-Ce olefins. In some examples, the metathesis reactor is one or more down-flow or up-flow, fixed bed reactors. The metathesis reactor can be operated in gas phase, liquid phase, or mixed phase. The metathesis reactor can operate at pressures ranging from about 0 barg to about 30 barg. The metathesis reactor can have an operating cycle time ranging from about 1 day to about 100 days. The metathesis reactor WHSV can range from about 0.1 h'1to about 25 h’1. For example, the metathesis WHSV can range from about 0.5 h'1to about 10 h’1.

[0047] Regeneration of metathesis reactor can be performed either using air, enriched air, or oxygen at temperatures ranging from about 300 °C to about 600 °C. For example, using air, the regeneration temperatures range from about 350 °C to 550 °C. In certain examples, two or more metathesis reactors are contained within the system with one of the metathesis reactors active while the other metathesis reactors are in standby mode until regeneration of the active metathesis reactor. The metathesis catalyst can be regenerated in-situ (online) and ex-situ (off-line) or can be a bunker flow reactor with continuous catalyst replacement.

[0048] The system also includes a C3 column. The C3 column is in fluid communication with the metathesis reactor and is configured to receive the metathesis product stream. The C3 column separates the metathesis product stream into a C2 / C3 product stream that contains ethene and propene and a C4+ olefins stream that contains but-l-ene, Cs-Ce olefins, and unreacted but-2-ene. In some examples, the C3 column is a depropenizer.

[0049] The system further includes a C2 / C3 splitter. The C2 / C3 splitter column is in fluid communication with the C3 column and is configured to receive the C2 / C3 product stream from the C3 column. The C2 / C3 splitter column separates the C2 / C3 product stream into an ethene product stream and a propene product stream.

[0050] In certain examples, the system includes a C4 column. The C4 column can be in fluid communication with the C3 column and is configured to receive a C4+ olefins stream. The C4 column separates the C4+ olefins stream into a C4 recycle stream that contains unreacted butene and Cs olefins and a Ce olefins stream that contains hex-3-ene and hex-l-ene. In certain examples, the C4 column is a debutenizer.

[0051] In some examples, the system includes a Ce isomerization reactor. The Ce isomerization reactor can a fixed bed plug flow reactor. The Ce isomerization reactor can be in fluid communication with the C4 column and is configured to receive a Ce olefins stream. The Ce isomerization reactor can operate at temperatures ranging from about 250 °C to 500 °C and contain the SABIC proprietary catalyst such as, K^O / y-AhCh-based catalyst while using a liquid feed, vapor feed, or mixed phase feed. The Ce isomerization reactor can operate at pressures ranging from about 0 barg to about 30 barg. The Ce isomerization reactor produce a hex-l-ene-rich stream. The Ce isomerization reactor can operate with operating cycle time ranging from about 1 day to about 100 days. The flow rate of the Ce olefins to the Ce isomerization reactor can operate with a WHSV ranging from about 0.1 h'1to about 25 h'1. For example, the Ce isomerization reactor can have a WHSV ranging from about 0.5 h’1to 10 h'1. Regeneration of the isomerization reactor can be performed either using nitrogen, air, enriched air, or oxygen at temperatures ranging from about 300 °C to 500 °C. In certain examples, the system can have two or more Ce isomerization reactors, one in operation while the other Ce isomerization reactors are under regeneration or standby.

[0052] In certain examples, the system includes a Ce fractionator. The Ce fractionator can be in fluid communication with the Ce isomerization reactor and is configured to receive the hex-l-ene- rich product stream. The Ce fractionator separates a substantially pure hex-l-ene product stream from hex-3 -ene and hex-2-ene.

[0053] In an example, a method for producing olefins such as hex-l-ene, ethene, and propene includes absorbing one or more contaminants from a C4 feed stream to output a pretreated C4 stream containing less than 15 mol. % of but-l-ene. The method further includes isomerizing the pretreated C4 stream to produce an isomerized C4 stream. The method also includes separating the isomerized C4 stream to produce (i) a but-l-ene stream containing unreacted but-2-ene, (ii) a butane-rich stream containing butane, and (iii) a but-2-ene-rich stream that is isomerized into the but-l-ene-rich stream. The method further includes metathesizing the but-l-ene-rich stream at temperatures ranging from about 35 °C to about 100 °C to produce a metathesis product stream. The method further includes separating the metathesis product stream to produce (i) a C2 / C3 product stream containing ethene and propene and (ii) a C4+ olefins stream containing unreacted but-l-ene, Cs olefins and Ce olefins. The method also includes splitting the C2 / C3 product stream to produce an ethene product stream and a propene product stream. The but-l-ene-rich stream is recycled back to metathesis reactor.

[0054] In some examples, the method can further include separating the C4+ olefins stream to produce (i) a C4 recycle stream containing the unreacted but-l-ene and (ii) a Cs-Ce olefins stream containing Cs olefins and Ce olefins and supplying the C4 recycle stream to be metathesized into the metathesis product stream.

[0055] In certain examples, the method further includes separating the C4+ olefins stream to produce (i) a C4-C5 recycle stream containing the unreacted but-l-ene and Cs olefins and (ii) a Ce olefins stream containing Ce olefins and supplying the C4-C5 recycle stream to be metathesized into the metathesis product stream. In some examples, the method includes isomerizing the Ce olefins to produce a hex-l-ene-rich stream containing hex-3 -ene, hex-2-ene, and hex-l-ene. Such example further includes separating the hex-l-ene-rich stream to produce (i) a substantially pure hex-l-ene stream and (ii) a hex-2-ene-rich stream containing hex-2-ene and hex-3 -ene and supplying the hex-2- ene and hex-3 -ene-ri ch stream to be isomerized into the hex-l-ene-rich stream.

[0056] In certain examples, the method further includes supplying the ethene product stream to be metathesized into the metathesis product stream. In certain examples, the method further includes separating the Cs-Ce olefins stream to produce (i) a Cs olefins stream and (ii) a Ce olefins stream and metathesizing the Cs olefins stream to produce (i) a second propene product stream and (ii) a but-l- ene product stream.

[0057] FIG. 1 is a schematic representation of a system 100 for the production of ethene and hex- l-ene using self-metathesis of but-l-ene and isomerization of Ce olefins and a butene feed stream that contains greater than or equal to 15 mol. % of but-l-ene, according to an example. The system 100includes a feed pre-treater 104 that receives a C4 feed stream 102 containing but-l-ene, but-2-ene, n- butene, n-butane, i-butane, i-butylene, and other components. The feed pre-treater 104 outputs a pretreated C4 stream 106. The pretreated C4 stream 106 contains greater than about 15 mol. % of but- l-ene. A C4 fractionator 112 is in fluid communication with the feed pre-treater 104 and is configured to receive the pretreated C4 stream 106. The system 100 further includes a C4 isomerization reactor 108 in fluid communication with the C4 fractionator 112 and is configured to receive the fractionated but-2-ene-rich stream 114. The C4 isomerization reactor 108 contains a SABIC proprietary catalyst, such as K2O / y-A12O3-based catalyst. The C4 isomerization reactor 108 produces an isomerized C4 stream 110 containing but-l-ene, butane, and unconverted but-2-ene. The C4 fractionator 112 is configured to receive the isomerized C4 stream 110. The C4 fractionator 112 fractionates the isomerized C4 stream 110 to produce a but-2-ene-rich stream 114 containing unreacted but-2-ene, a butane-rich stream 116 containing butane, and a but-l-ene-rich stream 118. In some examples, the but-l-ene-rich stream 118 contains but-l-ene and carryover but-2-ene based on the fractionation system. The fractionation of the isomerized C4 stream 110 produces the but-l-ene-rich stream 118 containing greater than or equal to 90 mol. % of but-l-ene. The but-2-ene-rich stream 114 is recycled to the C4 isomerization reactor 108 to obtain additional but-l-ene. The butane-rich stream 116 can be sold as-is, used for further processing in another system, and / or supplied to a total hydrogenation unit (THU) of a steam cracker to produce further ethene and propene.

[0058] In certain examples, the but-l-ene-rich stream 118 contains greater than or equal to 90 mol. % of but-l-ene. The but-l-ene-rich stream 118 is further subjected to metathesis. A metathesis reactor 120 is in fluid communication with the C4 fractionator 112 and is configured to receive the but-l-ene- rich stream 118. The metathesis reactor 120 can be a low-temperature self-metathesis fixed bed reactor that contains the SABIC proprietary metathesis catalyst, such as rhenium oxide-coated y- alumina-based catalyst. The metathesis reactor 120 operates at temperatures ranging from about 35 °C to about 100 °C. The metathesis reactor 120 operates at pressures ranging from about 0 barg to about 30 barg. The metathesis reactor 120 produces a metathesis product stream 122 containing ethene, propene, Cs-Ce olefins, and unreacted but-l-ene and but-2-ene. Optionally, the metathesis reactor 120 can be in fluid communication with the feed pre-treater 104. The metathesis reactor 120 can be configured to directly receive the pretreated C4 stream 106 that contains greater than or equal to 90 mol. % of but-l-ene to produce the metathesis product stream 122.

[0059] The system 100 also includes a C3 column 124 that is in fluid communication with the metathesis reactor 120 and is configured to receive the metathesis product stream 122. The C3 column124 produces a C2 / C3 product stream 126 containing ethene and propene and a C4+ olefins stream 128 containing Cs-Ce olefins and unreacted but-l-ene and but-2-ene. A C2 / C3 splitter 148 is in fluid communication with the C3 column 124 and is configured to receive the C2 / C3 product stream 126. The C2 / C3 splitter 148 separates the C2 / C3 product stream 126 into an ethene product stream 150 and a propene product stream 152. A C4 column 130 is in fluid communication with the C3 column 124 and is configured to receive the C4+ olefins stream 128. For example, the C4 column 130 can be a debutenizer. The C4 column 130 produces a C4 recycle stream 142 containing the unreacted but-l- ene, unreacted but-2-ene, and Cs olefins and a Ce olefins stream 132 containing Ce olefins. The C4 recycle stream 142 can be mixed with the but-l-ene-rich stream 118. The two streams can be supplied as a mixed stream or as individual feeds to the metathesis reactor 120 to increase the production of hex-l-ene and ethene. A portion 146 of the C4 recycle stream is removed from the system or is further processed at a liquified petroleum gas (LPG) facility. In some examples, the C4 recycle stream 142 is supplied to the metathesis reactor 120 directly.

[0060] A Ce isomerization reactor 134 is in fluid communication with the C4 column 130 and is configured to receive the Ce olefins stream 132. The Ce isomerization reactor 134 can contain the proprietary catalyst, such as the BGO / y-AhCh-based catalyst. The Ce isomerization reactor 134 operates at temperatures ranging from about 250 °C to about 500 °C and produces a hex-l-ene-rich stream 136 containing hex-3-ene, hex-2-ene, and hex-l-ene. A Ce fractionator 138 is in fluid communication with the Ce isomerization reactor 134 and is configured to receive the hex-l-ene-rich stream 136. The Ce fractionator 138 produces a substantially pure hex-l-ene stream 144 and a hex-3- ene-rich stream 140 containing hex-3-ene and hex-2-ene. The hex-3 -ene-ri ch stream 140 is recycled to the Ce isomerization reactor 134. In this example, the substantially pure hex-l-ene stream 144 and the ethene product stream 150 are the desirable products.

[0061] FIG. 2 is a schematic representation of a system 200 for the production of Ce olefins and ethene using a butene feed stream that contains greater than or equal to 15 mol. % of but-l-ene, according to an example. The system 200 includes a feed pre-treater 204 that receives a C4 feed stream 202 containing but-l-ene, but-2-ene, n-butene, n-butane, i-butane, i-butylene, and other components. The feed pre-treater 204 outputs a pretreated C4 stream 206. The pretreated C4 stream 206 contains greater than 15 mol. % of but-l-ene. A C4 fractionator 212 that is in fluid communication with the feed pre-treater 204 and is configured to receive the pretreated C4 stream 206. The system 200 further includes a C4 isomerization reactor 208 is in fluid communication with the C4 fractionator 212 and is configured to receive the separated but-2-ene-rich stream 214. The C4 isomerization reactor 208contains a SABIC proprietary catalyst, such as BUO / y-AhCh-based catalyst. The C4 isomerization reactor 208 produces an isomerized C4 stream 210 containing but-l-ene, butane, and unreacted / unconverted but-2-ene. The C4 fractionator 212 fractionates the isomerized C4 stream 210 to produce a but-2-ene-rich stream 214 containing unreacted but-2-ene, a butane-rich stream 216, and a but-1- ene-rich stream 218 containing but-l-ene and in some instances, carry over but-2-ene based on the fractionation system. The fractionation of the isomerized C4 stream 210 produces the but-l-ene-rich stream 218 containing greater than or equal to 90 mol. % of but-l-ene. The but-2-ene-rich stream 214 is recycled to the C4 isomerization reactor 208 to obtain additional but-l-ene. The butane-rich stream 216 can be sold as-is, used for further processing in another system, and / or supplied to a THU of a steam cracker.

[0062] With a but-l-ene-rich stream 218 containing greater than or equal to 90 mol. % of but-l- ene, the but-l-ene-rich stream 218 is metathesized. A metathesis reactor 220 is in fluid communication with C4 fractionator 212 and is configured to receive the but-l-ene-rich stream 218. The metathesis reactor 220 is a low-temperature self-metathesis fixed bed reactor that contains the SABIC proprietary metathesis catalyst, such as rhenium oxide-coated y-alumina-based catalyst. The metathesis reactor 220 operates at temperatures ranging from about 35 °C to about 100 °C. The metathesis reactor 220 operates at pressures ranging from about 0 barg to about 30 barg. The metathesis reactor 220 produces a metathesis product stream 222 containing ethene, propene, and C5- Ce olefins and unreacted but-l-ene and but-2-ene. Optionally, the metathesis reactor 220 can be in fluid communication with the feed pre-treater 204. The metathesis reactor 220 can be configured to receive pretreated C4 stream 205 containing greater than or equal to 90 mol. % of but-l-ene to produce the metathesis product stream 222.

[0063] The system 200 also includes a C3 column 224 that is in fluid communication with the metathesis reactor 220 and is configured to receive the metathesis product stream 222. The C3 column 224 produces a C2 / C3 product stream 226 containing ethene and propene and a C4+ olefins stream 228 containing Cs-Ce olefins, and unreacted but-l-ene and but-2-ene. A C2 / C3 splitter 238 is in fluid communication with the C3 column 224 and is configured to receive the C2 / C3 product stream 226. The C2 / C3 splitter 238 separates the C2 / C3 product stream 226 into an ethene product stream 240 and a propene product stream 242. A C4 column 230 is in fluid communication with the C3 column 224 and is configured to receive the C4+ olefins stream 228. For example, the C4 column 230 can be a debutenizer. The C4 column 230 produces a C4 recycle stream 232 containing the unreacted but-l- ene and but-2-ene and Cs olefins and a Ce olefins stream 234. In this example, the Ce olefins stream234 and the ethene product stream 240 are the desirable products. The Ce olefins stream 234 can be used as a gasoline booster.

[0064] The C4 recycle stream 232 mixes with the but-l-ene-rich stream 218, and the two streams are supplied to the metathesis reactor 220 to increase production of ethene and Ce olefins. A portion 236 of the C4 recycle stream is removed from the system, is further processed at a liquified petroleum gas (LPG) facility, and / or supplied to a THU of a steam cracker for further cracking into ethene and propene. In some examples, the C4 recycle stream 232 is supplied to the metathesis reactor 220 directly.

[0065] FIG. 3 is a schematic representation of a system for the production of ethene, propene and Cs and Ce olefins using a butene feed stream that contains less than 15 mol. % of but-l-ene, according to an example. The system 300 includes a feed pre-treater 304 that receives a C4 stream 302 containing but-l-ene, but-2-ene, n-butene, n-butane, i-butane, i-butylene, and other components. The feed pre- treater 304 outputs a pretreated C4 stream 306. Unlike system 100 and system 200, the pretreated C4 stream 306 in system 300 contains less than 15 mol. % of but-l-ene. To further increase the mol. % of but-l-ene, the system 300 includes a C4 isomerization reactor 308 that is in fluid communication with the feed pre-treater 304 and is configured to receive the pretreated C4 stream 306. The C4 isomerization reactor 308 can contain a SABIC proprietary catalyst, such as BGO / y-AhCh-based catalyst. The C4 isomerization reactor 308 produces an isomerized C4 stream 310 containing but-l- ene, butane, and unconverted / unreacted but-2-ene. The system 300 further includes a C4 fractionator 312 that is in fluid communication with the C4 isomerization reactor 308 and is configured to receive the isomerized C4 stream 310. The C4 fractionator 312 fractionates the isomerized C4 stream 310 to produce a but-2-ene stream 314 containing unreacted but-2-ene, a butane-rich stream 316 containing butane, and a but-l-ene-rich stream 318 containing but-l-ene and in some instances, carry over but- 2-ene. The fractionation of the isomerized C4 stream 310 produces the but-l-ene-rich stream 318 containing greater than to 15 mol. % of but-l-ene. The but-l-ene-rich stream in system 100 and system 200 contained greater than or equal to 90 mol. % of but-l-ene. The but-2-ene stream 314 is recycled to the C4 isomerization reactor 308 to obtain additional but-l-ene. The butane-rich stream 316 can be sold as-is or used for further processing in another system.

[0066] With a but-l-ene-rich stream 318 containing greater than to 15 mol. % of but-l-ene, the but-l-ene-rich stream 318 is subjected to metathesis. A metathesis reactor 320 is in fluid communication with the C4 fractionator 312 and is configured to receive the but-l-ene-rich stream 318. The metathesis reactor 320 is a low-temperature reactor. Cross-type metathesis of butenes or aself-metathesis of but-l-ene reactions take place in low temperature metathesis reactor that contains a proprietary metathesis catalyst, such as rhenium oxide-coated y-alumina-based catalyst. The selfmetathesis of but-l-ene results in production of ethene and hex-3-ene and the cross metathesis of but- l-ene and but-2-ene results in production of propene and pent-2-ene. The metathesis reactor 320 operates at temperatures ranging from about 35 °C to about 100 °C. The metathesis reactor 320 operates at pressures ranging from about 0 barg to about 30 barg. The metathesis reactor 320 produces a metathesis product stream 322 containing ethene, propene, but-l-ene, unreacted but-2-ene, and Cs- Ce olefins. Optionally, the metathesis reactor 320 can be in fluid communication with the feed pretreater 304. The metathesis reactor 320 can be configured to receive pretreated C4 stream 305 containing greater than 15 mol. % of but-l-ene to produce the metathesis product stream 322. The metathesis reactor 320 being receptive of a stream containing greater than 15 mol. % of but-l-ene, produces propene, ethene, C5 olefins, and Ce olefins.

[0067] The system 300 also includes a C3 column 324 that is in fluid communication with the metathesis reactor 320 and is configured to receive the metathesis product stream 322. The C3 column 324 produces a C2 / C3 product stream 326 containing ethene and propene and a C4+ olefins stream 328 containing Cs-Ce olefins and unreacted but-2-ene and but-l-ene. A C2 / C3 splitter 338 is in fluid communication with the C3 column 324 and is configured to receive the C2 / C3 product stream 326. The C2 / C3 splitter 338 separates the C2 / C3 product stream 326 into an ethene product stream 340 and a propene product stream 342. A C4 column 330 is in fluid communication with the C3 column 324 and is configured to receive the C4+ olefins stream 328. For example, the C4 column 330 can be a debutenizer. The C4 column 330 produces a C4 recycle stream 332 containing the unreacted but-2- ene and but-l-ene and a Cs-Ce olefins stream 334 containing Cs olefins and Ce olefins. In this example, the Cs-Ce olefins stream 334, the ethene product stream 340, and the propene product stream 342 respectively are the desirable products. The C5 olefins and Ce olefins in the Cs-Ce olefins stream 334 can be sold out as intermediate olefins based on the market demand for certain products, such as gasoline boosters utilizing the intermediate olefins.

[0068] The C4 recycle stream 332 which has less than 15% but-l-ene is either mixed with the but- 1-ene-rich stream 318, or supplied separately to the isomerization reactor 308 to increase production of but-l-ene. A portion 336 of the C4 recycle stream is removed from the system. In some examples, the C4 recycle stream 332, which is rich in but-l-ene (such as containing greater than 15 mol. %) is supplied via stream 344 to the metathesis reactor 320 directly or mixes with but-l-ene-rich stream 318 and together the two streams are supplied to the metathesis reactor 320.

[0069] FIG. 4 is a schematic representation of a system 400 for the production of Ce olefins, ethene, and propene using a Cs olefins recycle and a butene feed stream that contains less than 15 mol. % of but-l-ene, according to an example. The system 400 includes a feed pre-treater 404 that receives a C4 feed stream 402 containing but-l-ene, but-2-ene, n-butene, n-butane, i-butane, i- butylene, and other components. The feed pre-treater 404 outputs a pretreated C4 stream 406. Similar to the system 300, the pretreated C4 stream 406 in the system 400 contains less than 15 mol. % of but- l-ene. To further increase the mol. % of but-l-ene, the system 400 includes a C4 isomerization reactor 408 that is in fluid communication with the feed pre-treater 404 and is configured to receive the pretreated C4 stream 406. The C4 isomerization reactor 408 can contain a SABIC proprietary catalyst, such as K2O / y-A12O3-based catalyst. The C4 isomerization reactor 408 produces an isomerized C4 stream 410 containing but-l-ene, butane, and unreacted but-2-ene. The system 400 further includes a C4 fractionator 412 that is in fluid communication with the C4 isomerization reactor 408 and is configured to receive the isomerized C4 stream 410. The C4 fractionator 412 fractionates the isomerized C4 stream 410 to produce a but-2-ene stream 414 containing unreacted but-2-ene, a butane- rich stream 416 containing butane, and a C4 olefins-rich stream 418 containing but-l-ene and but-2- ene. The fractionation of the isomerized C4 stream 410 produces the C4 olefins-rich stream 418 containing greater than 15 mol. % of but-l-ene compared to the but-l-ene-rich stream in system 100 and system 200 which contained greater than or equal to 90 mol. % of but-l-ene. The but-2-ene stream 414 is recycled to the C4 isomerization reactor 408 to obtain additional but-l-ene. The butane-rich stream 416 can be sold as-is or used for further processing in another system.

[0070] With a C4 olefins-rich stream 418 containing greater than 15 mol. % of but-l-ene, the C4 olefins-rich stream 418 is metathesized. A metathesis reactor 420 is in fluid communication with C4 fractionator 412 and is configured to receive the C4 olefins-rich stream 418. The metathesis reactor 420 is a low-temperature reactor. Cross-type metathesis of butenes or self-metathesis of but-l-ene reactions take place in low temperature metathesis reactor that can contain the SABIC proprietary metathesis catalyst, such as rhenium oxide-coated y-alumina-based catalyst. The metathesis reactor 420 operates at temperatures ranging from about 35 °C to about 100 °C. The metathesis reactor 420 operates at pressures ranging from about 0 barg to about 30 barg. The metathesis reactor 420 produces a metathesis product stream 422 containing ethene, propene, Cs-Ce olefins and unreacted but-2-ene and but-l-ene. Optionally, the metathesis reactor 420 can be in fluid communication with the feed pre-treater 404. The metathesis reactor 420 can be configured to receive pretreated C4 stream 405 containing greater than 15 mol. % of but-l-ene to produce the metathesis product stream 422. Themetathesis reactor 420 being receptive of a stream containing greater than 15 mol. % of but-l-ene, produces propene, ethene, Cs olefins, and Ce olefins.

[0071] The system 400 also includes a C3 column 424 that is in fluid communication with the metathesis reactor 420 and is configured to receive the metathesis product stream 422. The C3 column 424 produces a C2 / C3 product stream 426 containing ethene and propene and a C4+ olefins stream 428 containing Cs-Ce olefins, and unreacted but-2-ene and but-l-ene. A C2 / C3 splitter 438 is in fluid communication with the C3 column 424 and is configured to receive the C2 / C3 product stream 426. The C2 / C3 splitter 438 separates the C2 / C3 product stream 426 into an ethene product stream 440 and a propene product stream 442. A C4 column 430 is in fluid communication with the C3 column 424 and is configured to receive the C4+ olefins stream 428. For example, the C4 column 430 can be a debutenizer. The C4 column 430 produces a C4 recycle stream 432 containing the unreacted but-l- ene and C5+ olefins stream 434. A Cs column 444 is in fluid communication with the C4 column 430 and is configured to receive the Cs+ olefins stream 434. For example, the Cs column 444 can be a depentenizer. The Cs column 444 produces a Cs recycle stream 446 containing pent-2-ene and a Ce olefins stream 450 containing Ce olefins. The Ce olefins in the Ce olefins stream 450 can be sold out as intermediate olefins based on the market demand.

[0072] The C4 recycle stream 432 may be supplied via Cs olefins recycle stream 448 to be mixed with the C4 olefins-rich stream 418 if the but-l-ene content of C4 recycle stream 432 is greater than or equal to 15 mol. %, and together the two streams are supplied to the metathesis reactor 420 to increase production of the Ce olefins. A portion 436 of the C4 recycle stream is removed from the system. In some examples, the C4 recycle stream 432 is supplied to the metathesis reactor 420 directly. In some examples, the C4 recycle stream 432 with but-l-ene content being less than 15 mol. % can be mixed with the pretreated C4 stream 406 and supplied to the isomerization reactor 408 to increase production of the but-l-ene.

[0073] The Cs olefins in the Cs olefins recycle stream 448 mix with the C4 olefins-rich stream 418 and together the two streams are supplied to the metathesis reactor 420 to increase production of propene and Ce olefins. In some examples, the Cs olefins recycle stream 448 is supplied to the metathesis reactor 420 directly.

[0074] FIG. 5 is a schematic representation of a system 500 for the production of hex-l-ene by isomerization of Ce olefins, and ethene and propene by metathesis of butenes. A butene feed stream that contains less than 15 mol. % of but-l-ene, and a Cs olefins recycle stream is supplied to a metathesis reactor to increase the production of hex-l-ene and propene, according to an example. Thesystem 500 includes a feed pre-treater 504 that receives a C4 feed stream 502 containing but-l-ene, but-2-ene, n-butene, n-butane, i-butane, i-butylene, and other components. The feed pre-treater 504 outputs a pretreated C4 stream 506. Similar to the system 300 and the system 400, the pretreated C4 stream 506 in the system 500 contains less than 15 mol. % of but-l-ene. To further increase the mol. % of but-l-ene, the system 500 includes a C4 isomerization reactor 508 is in fluid communication with the feed pre-treater 504 and is configured to receive the pretreated C4 stream 506. The C4 isomerization reactor 508 can contain a SABIC proprietary catalyst, such as K^O / v-AhCh-based catalyst. The C4 isomerization reactor 508 produces an isomerized C4 stream 510 containing but-l- ene, butane, and trace amounts of but-2-enes. The system 500 further includes a C4 fractionator 512 that is in fluid communication with the C4 isomerization reactor 508 and is configured to receive the isomerized C4 stream 510. The C4 fractionator 512 fractionates the isomerized C4 stream 510 to produce a but-2-ene stream 514 containing unreacted but-2-enes, a butane-rich stream 516 containing butane, and a C4 olefins-rich stream 518 containing but-l-ene and but-2-ene. The fractionation of the isomerized C4 stream 510 produces the C4 olefins-rich stream 518 containing greater than 15 mol. % of but-l-ene, as compared to the C4+ olefins stream in the system 100 and the system 200 which contained greater than or equal to 90 mol. % of but-l-ene. The but-2-ene stream 514 is recycled to the C4 isomerization reactor 508 to obtain additional but-l-ene. The butane-rich stream 516 can be sold as-is, used for further processing in another system, and / or supplied to a THU of a steam cracker.

[0075] With a C4 olefins-rich stream 518 containing greater than 15 mol. % of but-l-ene, the C4 olefins-rich stream 518 is subjected to metathesis. A metathesis reactor 520 is in fluid communication with the C4 fractionator 512 and is configured to receive the C4 olefins-rich stream 518. The metathesis reactor 520 is a low-temperature metathesis reactor. Cross-type metathesis of butenes reaction or self-metathesis of but-l-ene reaction take place in low temperature metathesis reactor that can contain a proprietary metathesis catalyst, such as rhenium oxide-coated y-alumina-based catalyst. The metathesis reactor 520 operates at temperatures ranging from about 35 °C to about 100 °C. The metathesis reactor 520 operates at pressures ranging from about 0 barg to about 30 barg. The metathesis reactor 520 produces a metathesis product stream 522 containing ethene, propene, and C5- Ce olefins and unreacted but-2-ene and but-l-ene. Optionally, the metathesis reactor 520 can be in fluid communication with the feed pre-treater 504. The metathesis reactor 520 can be configured to receive the pretreated C4 stream 505 containing greater than 15 mol. % of but-l-ene to produce the metathesis product stream 522. The metathesis reactor 520 being receptive of a stream containing greater than mol. % of but-l-ene, produces propene, ethene, C5 olefins, and Ce olefins.

[0076] The system 500 also includes a C3 column 524 that is in fluid communication with the metathesis reactor 520 and is configured to receive the metathesis product stream 522. The C3 column 524 produces a C2 / C3 product stream 526 containing ethene and propene and a C4+ olefins stream 528 containing but-l-ene, Cs-Ce olefins, and unreacted but-2-ene. A C2 / C3 splitter 546 is in fluid communication with the C3 column 524 and is configured to receive the C2 / C3 product stream 526. The C2 / C3 splitter 546 separates the C2 / C3 product stream 526 into an ethene product stream 548 and a propene product stream 547. A C4 column 530 is in fluid communication with the C3 column 524 and is configured to receive the C4+ olefins stream 528. For example, the C4 column 530 can be a debutenizer. The C4 column 530 produces a C4 recycle stream 552 containing the unreacted but-2- ene and but-l-ene and a Cs-Ce olefins stream 532. A Cs column 533 is in fluid communication with the C4 column 530 and is configured to receive the Cs-Ce olefins stream 532. For example, the Cs column 533 can be a depentenizer. The Cs column 533 produces a Cs recycle stream 555 containing the pent-2-ene and a Ce olefins stream 549.

[0077] In instances when the C4 recycle stream 552 contains but-l-ene at greater than 15 mol. %, the C4 recycle stream 552 is mixed with the C4 olefins-rich stream 518 via stream 550 and supplied to the metathesis reactor 520. The C4 olefins are supplied to the metathesis reactor 520 to increase production of the metathesis products. A portion 544 of the C4 recycle stream is removed from the system. In some examples, the C4 recycle stream 552 is supplied to the metathesis reactor 520 directly. In some examples, the C4 recycle stream 552 is mixed with the pretreated C4 stream 506 and together the two streams are supplied to the isomerization reactor 508 to increase production of the but-l-ene. The Cs olefins in the Cs recycle stream 555 mix with the C4 olefins-rich stream 518 and together the two streams are supplied to the metathesis reactor 520 to increase production of propene and Ce olefins.

[0078] A Ce isomerization reactor 534 is in fluid communication with the Cs column 533 and is configured to receive the Ce olefins stream 549. The Ce isomerization reactor 534 can contain the SABIC proprietary catalyst, such as the K^O / y-AhCh-based catalyst. The Ce isomerization reactor 534 operates at temperatures ranging from about 250 °C to about 500 °C and produces a hex-l-ene- rich stream 536 containing hex-3-ene, hex-2-ene, and hex-l-ene. A Ce fractionator 538 is in fluid communication with the Ce isomerization reactor 534 and is configured to receive the hex-l-ene-rich stream 536. The Ce fractionator 538 produces a substantially pure hex-l-ene stream 542 and a hex-3- ene-rich stream 540 containing hex-3-ene and hex-2-ene. The hex-3 -ene-ri ch stream 540 is recycledto the Ce isomerization reactor 534. In this example, the substantially pure hex-l-ene stream 542, the propene product stream 547, and the ethene product stream 548 are the desirable products.

[0079] FIG. 6 is a schematic representation of a system for the production of propene and hex-l- ene using metathesis of C4 olefins and followed by isomerization of Ce olefins, a butene feed stream that contains less than 15 mol. % of but-l-ene, and a partial recycle of ethene to increase the production of hex-l-ene and propene, according to an example. The system 600 includes a feed pretreater 604 that receives a C4 feed stream 602 containing but-l-ene, but-2-ene, n-butene, n-butane, i- butane, i-butylene, and other components. The feed pre-treater 604 outputs a pretreated C4 stream 606. The pretreated C4 stream 606 contains less than 15 mol. % of but-l-ene. To further increase the mol. % of but-l-ene, the system 600 includes a C4 isomerization reactor 608 that is in fluid communication with the feed pre-treater 604 and is configured to receive the pretreated C4 stream 606. The C4 isomerization reactor 608 can contain a SABIC proprietary catalyst, such as K2O / Y- AhCh-based catalyst. The C4 isomerization reactor 608 produces an isomerized C4 stream 610 containing but-l-ene, butane, and trace amounts of but-2-ene. The system 600 further includes a C4 fractionator 612 that is in fluid communication with the C4 isomerization reactor 608 and is configured to receive the isomerized C4 stream 610. The C4 fractionator 612 fractionates the isomerized C4 stream 610 to produce a but-2-ene stream 614 containing unreacted but-2-ene, a butane-rich stream 616 containing butane, and a C4 olefins-rich stream 618 containing but-l-ene and but-2-ene. The fractionation of the isomerized C4 stream 610 produces the C4 olefins-rich stream 618 containing about 15 mol. % of but-l-ene to about 60 mol. % of but-l-ene. The but-2-ene stream 614 is recycled to the C4 isomerization reactor 608 to obtain additional but-l-ene. The butane-rich stream 616 can be sold as-is, used for further processing in another system, and / or supplied to a THU of a steam cracker.

[0080] With the C4 olefins-rich stream 618 containing about 15 mol. % of but-l-ene to about 60 mol. % of but-l-ene, the C4 olefins-rich stream 618 is subjected to metathesis. A metathesis reactor 620 is in fluid communication with the C4 fractionator 612 and is configured to receive the C4 olefins- rich stream 618. The metathesis reactor 620 is a low-temperature metathesis reactor. Cross-type metathesis of butenes reaction and self-metathesis of but-l-ene reactions take place in low temperature metathesis reactor that can contain a proprietary metathesis catalyst, such as rhenium oxide-coated y-alumina-based catalyst. The metathesis reactor 620 operates at temperatures ranging from about 35 °C to about 100 °C. The metathesis reactor 620 operates at pressures ranging from about 0 barg to about 30 barg. The metathesis reactor 620 produces a metathesis product stream 622 containing ethene, propene, and Cs-Ce olefins, and unreacted but-l-ene and but-2-ene. Optionally,the metathesis reactor 620 can be in fluid communication with the feed pre-treater 604. The metathesis reactor 620 can be configured to receive pretreated C4 stream 605 containing greater than 15 mol. % of but-l-ene to produce the metathesis product stream 622. The metathesis reactor 620 being receptive of a stream containing greater than 15 mol. % of but-l-ene, produces propene, ethene, and Cs-Ce olefins.

[0081] The system 600 also includes a C3 column 624 that is in fluid communication with the metathesis reactor 620 and is configured to receive the metathesis product stream 622. The C3 column 624 produces a C2 / C3 product stream 626 containing ethene and propene and a C4+ olefins stream 628 containing Cs-Ce olefins and unreacted but-l-ene and but-2-ene. A C2 / C3 splitter 648 is in fluid communication with the C3 column 624 and is configured to receive the C2 / C3 product stream 626. The C2 / C3 splitter 648 separates the C2 / C3 product stream 626 into an ethene product stream 650 and a propene product stream 652. In some examples, the ethene product stream 650 can be recycled to the metathesis reactor 620 via an ethene recycle stream 654. Recycling the ethene recycle stream 654 increases the production of substantially pure hex-l-ene and propene, both being desirable products. In certain examples, an ethene product stream 651 including all or a portion of the ethene product stream 650 is sold as-is. A C4 column 630 is in fluid communication with the C3 column 624 and is configured to receive the C4+ olefins stream 628. For example, the C4 column 630 can be a debutenizer. The C4 column 630 produces a C4 recycle stream 632 containing the unreacted but-l- ene and but-2-ene and also a Cs+ olefins stream 631 containing Cs-Ce olefins. A Cs column 633 is in fluid communication with the C4 column 630 and is configured to receive the C5+ olefins stream 631. For example, the Cs column 633 can be a depentenizer. The Cs column 633 produces a Cs olefins recycle stream 635 containing the pent-2-ene and a Ce olefins stream 634 containing Ce olefins.

[0082] The C4 recycle stream 632, when containing but-l-ene at greater than 15 mol. %, is mixed with the C4 olefins-rich stream 618 via stream 641, and supplied to the metathesis reactor 620. The Cs olefins in the Cs olefins recycle stream 635 are supplied to the metathesis reactor 620 to increase production of the metathesis products — C3 and Ce olefins. A portion 646 of the C4 recycle stream is removed from the system. In some examples, the C4 recycle stream 632 is supplied to the metathesis reactor 620 directly. In some examples, the C4 recycle stream 632 (when the but-l-ene content is less than 15 mol. %) is mixed with the pretreated C4 stream 606 and supplied to the isomerization reactor 608 to increase production of the but-l-ene. The Cs olefins in the Cs olefins recycle stream 635 mixes with the C4 olefins-rich stream 618 and are supplied to the metathesis reactor 620 to increase production of propene and Ce olefins.

[0083] A Ce isomerization reactor 636 is in fluid communication with the Cs column 633 and is configured to receive the Ce olefins stream 634. The Ce isomerization reactor 636 can contain the SABIC proprietary catalyst, such as the BUO / y-AhCh-based catalyst. The Ce isomerization reactor 636 operates at temperatures ranging from about 250 °C to about 500 °C and produces a hex-l-ene- rich stream 638 containing hex-3-ene, hex-2-ene, and hex-l-ene. A Ce fractionator 640 is in fluid communication with the Ce isomerization reactor 636 and is configured to receive the hex-l-ene-rich stream 638. The Ce fractionator 640 produces a substantially pure hex-l-ene stream 644 and a hex-3- ene-rich stream 642 containing hex-3-ene and hex-2-ene. The hex-3 -ene-ri ch stream 642 is recycled to the Ce isomerization reactor 636. In this example, the substantially pure hex-l-ene stream 644, the ethene product stream 651, and the propene product stream 652 are the desirable products.

[0084] FIG. 7 is a schematic representation of a system 700 for the production of hexenes, but-1- ene, and propene using a butene feed stream that contains less than 15 mol. % of but-l-ene and two metathesis reactors to increase the production of hexenes, but-l-ene, and propene, according to an example. The system 700 includes a feed pre-treater 704 that receives a C4 feed stream 702 containing but-l-ene, but-2-ene, n-butene, n-butane, i-butane, i-butylene, and other components. The feed pre- treater 704 outputs a pretreated C4 stream 706. The pretreated C4 stream 706 contains less than 15 mol. % of but-l-ene. To further increase the mol. % of but-l-ene, the system 700 includes a C4 isomerization reactor 708 is in fluid communication with the feed pre-treater 704 and is configured to receive the pretreated C4 stream 706. The C4 isomerization reactor 708 can contain a proprietary catalyst, such as BUO / y-AUCh-based catalyst. The C4 isomerization reactor 708 produces an isomerized C4 stream 710 containing but-l-ene, butane, and trace amounts of but-2-ene. The system 700 further includes a C4 fractionator 712 that is in fluid communication with the C4 isomerization reactor 708 and is configured to receive the isomerized C4 stream 710. The C4 fractionator 712 fractionates the isomerized C4 stream 710 to produce a but-2-ene stream 714 containing unreacted but-2-ene, a butane-rich stream 716, and a C4 olefins-rich stream 718 containing but-l-ene and but- 2-ene. The fractionation of the isomerized C4 stream 710 produces the C4 olefins-rich stream 718 containing about 15 mol. % of but-l-ene to about 60 mol. % of but-l-ene. The but-2-ene stream 714 is recycled to the C4 isomerization reactor 708 to obtain additional but-l-ene. The butane-rich stream 716 can be sold as-is, used for further processing in another system, and / or supplied to a THU of a steam cracker.

[0085] With a C4 olefins-rich stream 718 containing about 15 mol. % of but-l-ene to about 60 mol. % of but-l-ene, the C4 olefins-rich stream 718 is subjected to metathesis. A first metathesis reactor720 is in fluid communication with C4 fractionator 712 and is configured to receive the C4 olefins- rich stream 718. The first metathesis reactor 720 is a low-temperature metathesis reactor. Cross-type metathesis of butenes reaction or self-metathesis of but-l-ene reaction take place in low temperature metathesis reactor that can contain a proprietary metathesis catalyst, such as rhenium oxide-coated y- alumina-based catalyst. The first metathesis reactor 720 operates at temperatures ranging from about 35 °C to about 100 °C. The first metathesis reactor 720 operates at pressures ranging from about 0 barg to about 30 barg. The first metathesis reactor 720 produces a metathesis product stream 722 containing ethene, propene, Cs-Ce olefins, and unreacted but-l-ene and but-2-ene. Optionally, the first metathesis reactor 720 can be in fluid communication with the feed pre-treater 704. The first metathesis reactor 720 can be configured to receive pretreated C4 stream 705 containing greater than 15 mol. % of but-l-ene to produce the metathesis product stream 722. The first metathesis reactor 720 being receptive of a stream containing greater than 15 mol. % of but-l-ene, produces propene, ethene, C5 olefins, and Ce olefins.

[0086] The system 700 also includes a C3 column 724 that is in fluid communication with the first metathesis reactor 720 and is configured to receive the metathesis product stream 722. The C3 column 724 produces a C2 / C3 product stream 726 containing ethene and propene and a C4+ olefins stream 728 containing Cs-Ce olefins, and unreacted but-l-ene and but-2-ene. A C2 / C3 splitter 748 is in fluid communication with the C3 column 724 and is configured to receive the C2 / C3 product stream 726. The C2 / C3 splitter 748 separates the C2 / C3 product stream 726 into an ethene product stream 752 and a first propene product stream 750. A C4 column 730 is in fluid communication with the C3 column 724 and is configured to receive the C4+ olefins stream 728. For example, the C4 column 730 can be a debutenizer. The C4 column 730 produces a C4 recycle stream 732 containing the unreacted but-l- ene and but-2-ene and a Cs-Ce olefins stream 734 containing Cs olefins and Ce olefins. A Cs column 740 is in fluid communication with the C4 column 730 and is configured to receive the Cs-Ce olefins stream 734. For example, the Cs column 740 can be a depentenizer. The Cs column 740 separates the Cs-Ce olefins stream 734 into a Cs olefins stream 738 and a Ce olefins stream 736. The Ce olefins in the Ce olefins stream 736 can be sold out as intermediate olefins based on the market demand, which can used as a gasoline boosters or sent to pygas hydrogenation unit to steam cracker.

[0087] A second metathesis reactor 742 is in fluid communication with the Cs column 740 and is configured to receive the Cs olefins stream 738 and the ethene product stream 752. The second metathesis reactor 742 is a low-temperature metathesis reactor. Cross-type metathesis of pent-2-ene with ethene or self-metathesis of pent-2-ene reactions take place in low temperature metathesis reactorthat can contain a proprietary metathesis catalyst, such as the rhenium oxide-coated y-alumina-based catalyst. The second metathesis reactor 742 operates at temperatures ranging from about 35 °C to about 100 °C. The second metathesis reactor 742 operates at pressures ranging from about 0 barg to about 30 barg. The Cs olefins stream 738 is metathesized to produce a second propene product stream 746 and a but-l-ene product stream 744. The but-l-ene product stream 744 can be sold as-is. The addition of the ethene product stream 752 to the second metathesis reactor 742 increases the production of propene in the system 700.

[0088] The C4 recycle stream 732 (in instances when the but-l-ene content is greater than 15 mol. %) is mixed with the C4 olefins-rich stream 718, and supplied to the first metathesis reactor 720 to increase production of Ce olefins, ethene, and propene. A portion 756 of the C4 recycle stream is removed from the system. In some examples, the C4 recycle stream 732 is supplied to the first metathesis reactor 720 directly, such as via stream 733. In some examples, the C4 recycle stream 732 (in instances when but-l-ene content is less than 15 mol. %) is mixed with the pretreated C4 stream 706 and supplied to the isomerization reactor 708 to increase production of the but-l-ene.

[0089] FIG. 8 is a schematic representation of an example of a control system 800 for controlling the examples of the systems discussed above. The control system 800 includes at least one controller 801. Each controller 801 includes at least one processor 802, which can be or include a central processing unit (CPU), a graphics processing unit (GPU), a co-processing unit, a sub-processing unit, or any other suitable electronic data processor. Each controller 801 includes at least one memory 803, which can be or include random access memory (RAM), read-only memory (ROM), or any other suitable electronic memory or storage. For the illustrated example, the controller 801 is communicatively connected to each of the units present in a particular implementation of the systems discussed above, such as the feed pre-treater 804, the C4 isomerization reactor 806, the C4 fractionator 808, the metathesis reactor 810, the C3 column 812, and the C2 / C3 splitter 814. In certain examples, one or more of the C4 column 816, the Cs column 818, the Ce isomerization reactor 820, the Ce fractionator 822, and the second metathesis reactor 824 can be communicatively connected to the controller 801. The controller 801 is further communicatively connected to certain other elements of the systems discussed above, such as a flow control device. The communicative connection between the controller 801 and the units and devices enables the controller 801 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 801 to provide control signals (forexample, electrical signals, instructions, and data packets) to modify the operation of each of these zones or devices.

[0090] For example, the controller 801 can receive monitoring data from sensors (for example, temperature sensors, pressure sensors, and flow sensors) of the feed pre-treater 804 and based on predefined values for certain operational parameters, can provide suitable control signals to modify the operation of one or more components of the feed pre-treater 804 to ensure that the feed pre-treater 804 operates within the temperatures and pressures disclosed above. The controller 801 can receive monitoring data from sensors (for example, temperature sensors, pressure sensors, and flow sensors) of the C4 isomerization reactor 806, and based on predefined values for certain operational parameters, can provide suitable control signals to modify the operation of one or more components of the C4 isomerization reactor 806 to ensure that the C4 isomerization reactor 806 operates within the temperatures, pressures, and WHSV disclosed above, and to manage the regeneration mode operation and standby operation of the C4 isomerization reactor 806 and maybe even a second C4 isomerization reactor. The controller 801 can receive monitoring data from sensors (for example, temperature sensors, pressure sensors, and flow sensors) of the C4 fractionator 808 and based on predefined values for certain operational parameters, can provide suitable control signals to modify the operation of one or more components of the C4 fractionator 808 to ensure that the C4 fractionator 808 operates within the temperatures and pressures disclosed above. The controller 801 can receive monitoring data from sensors (for example, temperature sensors, pressure sensors, and flow sensors) of the metathesis reactor 810, and based on predefined 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 810 operates within the temperatures, pressures, and WHSV disclosed above, and to manage the regeneration mode operation and standby operation of the metathesis reactor 810 and maybe even a second metathesis reactor.

[0091] The controller 801 can receive monitoring data from sensors (for example, temperature sensors, pressure sensors, and flow sensors) of the C3 column 812 and based on predefined values for certain operational parameters, can provide suitable control signals to modify the operation of one or more components of the C3 column 812 to ensure that the C3 column 812 operates within the temperatures and pressures disclosed above. The controller 801 can receive monitoring data from sensors (for example, temperature sensors, pressure sensors, and flow sensors) of the C2 / C3 splitter 814 and based on predefined values for certain operational parameters, can provide suitable controlsignals to modify the operation of one or more components of the C2 / C3 splitter 814 to ensure that the C2 / C3 splitter 814 operates within the temperatures and pressures disclosed above.

[0092] In certain examples, the controller 801 can receive monitoring data from sensors (for example, temperature sensors, pressure sensors, and flow sensors) of the C4 column 816 and, based on predefined values for certain operational parameters, can provide suitable control signals to modify the operation of one or more components of the C4 column 816 to ensure that the C4 column 816 operates within the temperatures and pressures disclosed above. In certain examples, the controller 801 can receive monitoring data from sensors (for example, temperature sensors, pressure sensors, and flow sensors) of the Cs column 818 and, based on predefined values for certain operational parameters, can provide suitable control signals to modify the operation of one or more components of the Cs column 818 to ensure that the Cs column 818 operates within the temperatures and pressures disclosed above. In certain examples, the controller 801 can receive monitoring data from sensors (for example, temperature sensors, pressure sensors, and flow sensors) of the Ce isomerization reactor 820, and based on predefined values for certain operational parameters, can provide suitable control signals to modify the operation of one or more components of the Ce isomerization reactor 820 to ensure that the Ce isomerization reactor 820 operates within the temperatures, pressures, and WHSV disclosed above, and to manage the regeneration mode operation and standby operation of the Ce isomerization reactor 820 and maybe even a second Ce isomerization reactor.

[0093] The controller 801 can receive monitoring data from sensors (for example, temperature sensors, pressure sensors, and flow sensors) of the Ce fractionator 822 and based on predefined values for certain operational parameters, can provide suitable control signals to modify the operation of one or more components of the Ce fractionator 822 to ensure that the C4 fractionator 808 operates within the temperatures and pressures disclosed above.

[0094] In certain examples, the controller 801 can receive monitoring data from sensors (for example, temperature sensors, pressure sensors, and flow sensors) of the second metathesis reactor 824, and based on predefined 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 second metathesis reactor 824 operates within the temperatures, pressures, and WHSV disclosed above, and to manage the regeneration mode operation and standby operation of the second metathesis reactor 824 and maybe even a third metathesis reactor.

[0095] In certain examples, the controller 801 can provide control signals to modify the operation of the flow control device to adjust the quantity of the streams that is directed to one or more of thefeed pre-treater 804, the C4 isomerization reactor 806, the C4 fractionator 808, the metathesis reactor 810, the C3 column 812, the C2 / C3 splitter 814, the C4 column 816, the Cs column 818, the Ce isomerization reactor 820, the Ce fractionator 822, and the second metathesis reactor 824. In certain embodiments, the controller 801 is configured to receive monitoring data from the feed analyzer unit regarding the concentration of but-l-ene in each of the received streams, such as the butene feed stream or butene feedstock stream.Examples

[0096] 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. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but deviations should be accounted for.

[0097] 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. Only reasonable and routine experimentation will be required to optimize such process conditions.

[0098] Example 1:

[0099] Experiments were performed implementing the process configuration of system 100, as discussed herein. The ultimate yields were calculated using preliminary lab experimental results. Reaction conditions for the experiment included a reaction temperature of 50 °C, a pressure of 6 barg, and a WHSV of 0.6 h'1. The sample feedstock composition is illustrated below in Table 2. The experimental results are confirmed with simulation results using ASPEN PLUS®, provided by Aspen Technology, Inc. of Bedford, Massachusetts, U.S.A. Table 3 illustrates the resulting product composition, which include C4 recycle calculated using Aspen simulations. It is noted that in some examples, purge removal may be implemented to remove any inert component accumulation at the metathesis reactor. These results demonstrate the benefit of C4 isomerization, metathesis, and Ce isomerization with C4 recycle to the metathesis reactor.

[0100] Table 2: Example feedstock composition of C4 feed stream

[0101] Table 3: Resulting product composition via C4 isomerization, metathesis, and Ce isomerization with C4 recycle to the metathesis reactor.

[0102] Example 2:

[0103] Experiments were performed implementing the process configuration of system 500, as discussed herein. The ultimate yields were calculated using preliminary lab experimental results. Reaction conditions for the experiment included a reaction temperature of 50 °C, a pressure of 6 barg, and a WHSV of 0.6 h'1. The sample feedstock composition is illustrated above in Table 2. The experimental results are confirmed with simulation results using ASPEN PLUS. Table 4 illustrates the resulting product composition, which include C5 olefins recycle calculated using Aspen simulations. It is noted that in some examples, purge removal may be implemented to remove any inert component accumulation at the metathesis reactor. These results demonstrate the benefit of C5 recycle to the metathesis reactor, Ce isomerization with a mixed feed C4 olefins to the metathesis reactor.

[0104] Table 4: Resulting product composition via C5 recycle to the metathesis reactor, Ce isomerization with a mixed feed C4 olefins to the metathesis reactor.

[0105] Example 3:

[0106] Experiments were performed implementing the process configuration of system 300, as discussed herein. The yields were calculated using preliminary lab experimental results. The system 300 of FIG. 3 was simulated to determine the composition of the isomerized C4 stream 310. For this example, the composition of the C4 stream 302 is indicated as the Raffinate-III stream in Table 5. For this example, the C4 stream 302 is isomerized produce but-l-ene from but-2-ene at an operatingtemperature ranging from about 100 °C to about 600 °C, an operating pressure ranging from about 0 barg and 30 barg, and a WHSV from about 0.1 h'1to about 20 h'1. The composition of the isomerized C4 stream 310 was calculated using lab experimental results, as indicated in Table 5, with varying isomerization reaction temperature, and the experimental results were confirmed using the commercial simulator. For this example, no effect was observed when the operating pressure or the WHSV were varied. However, as the isomerization catalyst deactivates faster with increased WHSV, it was observed that a WHSV of 0.6 hr1resulted in the isomerization catalyst being stable for 30 days. It was further observed that only but-2-ene were isomerized to but-l-ene within the isomerization reactor, despite the presence of other unsaturated C4 species in the C4 stream 302.

[0107] Table 5.

[0108] 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.

[0109] 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 embodiments of the disclosure, are given by way of illustration only and are not meant to be limiting. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In furtherembodiments, additional features may be added to the specific embodiments described herein. It should be understood that although the disclosure contains certain aspects, embodiments, and optional features, modification, improvement, or variation of such aspects, embodiments, 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. An olefin production system, the system comprising: a feed pre-treater configured to receive a C4 feed stream and output a pretreated C4 stream; a C4 isomerization reactor containing a K^O / y-AhCh-based catalyst in fluid communication with the feed pre-treater and configured to receive the pretreated C4 stream and produce an isomerized C4 stream; a C4 fractionator in fluid communication with the C4 isomerization reactor and configured to receive the isomerized C4 stream and produce (i) a but-2-ene stream containing unreacted but-2-ene, (ii) a butane-rich stream containing butane, and (iii) a C4 olefins-rich stream containing but- 1-ene and but-2-ene, the but-2-ene stream received by the C4 isomerization reactor; a metathesis reactor containing a rhenium oxide-coated y-alumina-based catalyst in fluid communication with the C4 fractionator and configured to receive the C4 olefins-rich stream and produce a metathesis product stream containing ethene, propene, Cs-Ce olefins, and unreacted but-l-ene and but-2-ene, the metathesis reactor being operated at temperatures ranging from about 35 °C to about 100 °C; a C3 column in fluid communication with the metathesis reactor and configured to receive the metathesis product stream and produce a C2 / C3 product stream containing ethene and propene and a C4+ olefins stream containing Cs-Ce olefins and unreacted but-l-ene and but-2-ene; a C4 column in fluid communication with the C3 column and configured to receive the C4+ olefins stream and produce a C4 recycle stream containing the unreacted but-l-ene and but-2-ene and a Cs-Ce olefins stream containing Cs olefins and Ce olefins, the C4 recycle stream being supplied to the metathesis reactor; and a C2 / C3 splitter column in fluid communication with the C3 column and configured to receive the C2 / C3 product stream and produce an ethene product stream and a propene product stream.

2. The system of claim 1, further comprising: a Ce isomerization reactor containing K^O / y-AhCh-based catalyst in fluid communication with the C4 column and configured to receive the Cs-Ce olefins stream and produce a hex-l-ene-rich stream containing hex-3-ene, hex-2-ene, and hex-l-ene, the Ce isomerization reactor being operated at temperatures ranging from about 250 °C to about 500 °C; anda Ce fractionator in fluid communication with the Ce isomerization reactor and configured to receive the hex-l-ene-rich stream and produce a substantially pure hex-l-ene stream and a hex-3-ene- rich stream containing hex-3 -ene and hex-2-ene, the hex-3 -ene-ri ch stream being recycled to the Ce isomerization reactor.

3. The system of claim 1, further comprising: a Cs column in fluid communication with the C4 column and configured to receive the Cs-Ce olefins stream and produce a C5 olefins stream and a Ce olefins stream; and a second metathesis reactor containing the rhenium oxide-coated y-alumina-based catalyst in fluid communication with the Cs column and configured to receive the Cs olefins stream and the ethene product stream and produce a second propene product stream and a but- 1 -ene product stream, the second metathesis reactor being operated at temperatures ranging from about 35 °C to about 100 °C and at pressures ranging from about 0 bar gauge (barg) to about 30 barg.

4. The system of claim 1, wherein the C4 olefins-rich stream contains about 15 molar percent (mol. %) of but- 1 -ene to about 60 mol. % of but- 1 -ene.

5. The system of claim 1, wherein the C4 olefins-rich stream contains greater than or equal to 90 mol. % of but- 1 -ene.

6. An olefin production system, the system comprising: a feed pre-treater configured to receive a C4 feed stream and output a pretreated C4 stream; a C4 isomerization reactor containing a K^O / y-AhCh-based catalyst in fluid communication with the feed pre-treater and configured to receive the pretreated C4 stream and produce an isomerized C4 stream; a C4 fractionator in fluid communication with the C4 isomerization reactor and configured to receive the isomerized C4 stream and produce (i) a but-2-ene stream containing unreacted but-2-ene, (ii) a butane-rich stream containing butane, and (iii) a C4 olefins-rich stream containing but- 1-ene and but-2-ene, the but-2-ene stream being supplied to the C4 isomerization reactor; a metathesis reactor containing a rhenium oxide-coated y-alumina-based catalyst in fluid communication with the C4 fractionator and configured to receive the C4 olefins-rich streamand produce a metathesis product stream containing ethene, propene, Cs-Ce olefins and unreacted but-l-ene and but-2-ene, the metathesis reactor being operated at temperatures ranging from about 35 °C to about 100 °C; a C3 column in fluid communication with the metathesis reactor and configured to receive the metathesis product stream and produce a C2 / C3 product stream containing ethene and propene and a C4+ olefins stream containing Cs-Ce olefins and unreacted but-l-ene and but-2-ene; a Cs column in fluid communication with the C3 column and configured to receive the C4 olefins-rich stream and produce a C4-C5 recycle stream containing the unreacted but-l-ene and but-2-ene and Cs olefins and a Ce olefins stream containing Ce olefins, the C4-C5 recycle stream being supplied to the metathesis reactor; and a C2 / C3 splitter column in fluid communication with the C3 column and configured to receive the C2 / C3 product stream and produce an ethene product stream and a propene product stream.

7. The system of claim 6, further comprising: a Ce isomerization reactor containing K^O / y-AhCh-based catalyst in fluid communication with the Cs column and configured to receive the Ce olefins stream and produce a hex-l-ene-rich stream containing hex-3-ene, hex-2-ene, and hex-l-ene, the Ce isomerization reactor operates at temperatures ranging from about 250 °C to about 500 °C; and a Ce fractionator in fluid communication with the Ce isomerization reactor and configured to receive the hex-l-ene-rich stream and produce (i) a substantially pure hex-l-ene stream and (ii) a hex- 3-ene-rich stream containing hex-3 -ene and hex-2-ene, the hex-3 -ene-ri ch stream recycled to the Ce isomerization reactor.

8. The system of claim 6, wherein a portion of the ethene product stream is recycled to the metathesis reactor.

9. The system of claims 1 or 6, wherein the metathesis reactor is in fluid communication with the feed pre-treater and configured to receive the pretreated C4 stream in response to the pretreated C4 stream containing greater than 15 mol. % of but-l-ene.

10. A method for producing olefins, the method comprising:absorbing one or more contaminants from a C4 feed stream to output a pretreated C4 stream containing less than 15 mol. % of but-l-ene; isomerizing the pretreated C4 stream to produce an isomerized C4 stream; separating the isomerized C4 stream to produce (i) a but-2-ene stream containing unreacted but-2-ene, (ii) a butane-rich stream containing butane, and (iii) a but-l-ene-rich stream, the but-2-ene stream being further isomerized into the isomerized C4 stream; metathesizing the but-l-ene-rich stream at temperatures ranging from about 35 °C to about 100 °C to produce a metathesis product stream; separating the metathesis product stream to produce a C2 / C3 product stream containing ethene and propene and a C4+ olefins stream containing Cs olefins and unreacted but-l-ene and but-2- ene; and splitting the C2 / C3 product stream to produce an ethene product stream and a propene product stream.

11. The method of claim 10, further comprising: separating the C4+ olefins stream to produce a C4 recycle stream containing the unreacted but-l-ene and but-2-ene and a Cs-Ce olefins stream containing Cs olefins and Ce olefins; and supplying the C4 recycle stream to be metathesized into the metathesis product stream.

12. The method of claim 11, further comprising: separating the Cs-Ce olefins stream to produce a Cs olefins stream and a Ce olefins stream; and metathesizing the Cs olefins stream to produce a second propene product stream and (ii) a but-l-ene product stream.

13. The method of claim 10, further comprising: separating the C4+ olefins stream to produce a C4-C5 recycle stream containing the unreacted but-l- ene and but-2-ene and Cs olefins and a Ce olefins stream containing Ce olefins; and supplying the C4-C5 recycle stream to be metathesized into the metathesis product stream.

14. The method of claim 13, further comprising: isomerizing the Ce olefins stream to produce a hex-l-ene-rich stream containing hex-3-ene, hex-2- ene, and hex-l-ene;separating the hex-l-ene-rich stream to produce a substantially pure hex-l-ene stream and a hex-3- ene-rich stream containing hex-3 -ene and hex-2-ene; and supplying the hex-3 -ene-ri ch stream to be isomerized into the hex-l-ene-rich stream.

15. The method of claim 10, further comprising: supplying a portion of the ethene product stream to be metathesized into the metathesis product stream.

Images