Process for purifying linear alpha olefins

Abstract

The present disclosure provides a catalytic process for the selective isomerization of 2-ethyl-1-butene in a linear alpha olefin stream, the catalytic process comprising: feeding a linear alpha olefin stream comprising linear alpha olefins and 2-ethyl-1-butene to a reactor containing a modified alumina catalyst to isomerize at least a portion of the 2-ethyl-1-butene to cis- or trans-3-methyl-2-pentene, wherein the period during which the feeding occurs is a flow time; withdrawing an effluent from the reactor containing less 2-ethyl-1-butene than the linear alpha olefin stream; and periodically regenerating the modified alumina catalyst by introducing a non-oxidizing environment into the reactor at flow time intervals of not more than about 200 hours, wherein the reactor is subjected to the non-oxidizing environment for a period of about 15 hours or longer, and the non-oxidizing environment has a temperature of about 250°C or greater for at least a portion of the period.

Description

[Technical Field]

[0001] The present disclosure relates to a process for purifying a linear alpha olefin product stream from an oligomerization reaction. [Background technology]

[0002] Linear olefins are a class of hydrocarbons useful as raw materials in the petrochemical industry. Among these linear alpha olefins, unbranched olefins, whose double bonds are located at the ends of the chain, form an important subclass. Linear alpha olefins can be converted to linear primary alcohols by hydroformylation. Hydroformylation can also be used to prepare aldehydes, which can be oxidized to provide synthetic fatty acids, particularly those with odd carbon numbers, useful in the production of lubricants. Linear alpha olefins are also used in the production of detergents, such as linear alkylbenzene sulfonates, which are prepared by the Fiedel-Crafts reaction of benzene with linear olefins followed by sulfonation. Another important use of linear alpha olefins relates to the production of linear low-density polyethylene (LLDPE) through catalytic copolymerization with ethylene.

[0003] The preparation of alpha olefins is largely based on the oligomerization of ethylene, which inevitably results in the alpha olefins produced having an even number of carbon atoms. The oligomerization process for ethylene primarily utilizes organoaluminum compounds or transition metals as catalysts. The oligomerization process is typically carried out in the presence of a catalyst containing a zirconium component, such as zirconium tetraisobutyrate, and an aluminum component as an activator, such as ethylaluminum sesquichloride. Typically, the effluent from the reactor used to produce linear alpha olefins is directed to one or more distillation columns to separate various fractions of linear alpha olefins. Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable to purify the alpha olefins from an oligomerization reaction to very high purity levels, such as greater than 99.5 wt. %. Achieving such high purity can be challenging using conventional separation processes due to the presence of impurities with boiling points very close to that of the target alpha olefin product. Improved separation processes for such products remain a need in the art. [Means for solving the problem]

[0005] (Summary of the Invention) An exemplary implementation of the present disclosure is directed to a process for purifying a linear alpha olefin product stream, which involves using modified alumina to isomerize 2-ethyl-1-butene into an isomer that is more easily removed from 1-hexane by distillation. The use of modified alumina catalyst in this manner can improve the separation efficiency of a distillation column, allowing the target linear alpha olefin to be purified to very high purity levels. The present disclosure also provides a catalytic process for the selective isomerization of 2-ethyl-1-butene in a linear alpha olefin product stream, which includes periodically regenerating the modified alumina catalyst using a non-oxidizing environment for a period of time and at a temperature that allows for continued use of the catalyst at peak performance levels.

[0006] The present disclosure includes, but is not limited to, the following embodiments.

[0007] Embodiment 1: A catalytic process for the selective isomerization of 2-ethyl-1-butene in a linear alpha olefin product stream, comprising: feeding a linear alpha olefin product stream comprising at least one linear alpha olefin, such as 1-hexene and 2-ethyl-1-butene, to a reactor containing a modified alumina catalyst to isomerize at least a portion of the 2-ethyl-1-butene to cis- or trans-3-methyl-2-pentene, wherein the period of time during which the feeding occurs is the flow time; withdrawing an effluent from the reactor containing less 2-ethyl-1-butene than the linear alpha olefin product stream; and periodically regenerating the modified alumina catalyst by stopping the feeding step and introducing a non-oxidizing environment to the reactor for a flow time interval of not more than about 200 hours, wherein the reactor is subjected to the non-oxidizing environment for a period of about 15 hours or longer, the non-oxidizing environment having a temperature of about 250° C. or greater for at least a portion of the period.

[0008] Embodiment 2: The catalytic process of embodiment 1, wherein the non-oxidizing environment comprises a vacuum environment or an inert gas environment, such as a nitrogen or noble gas environment.

[0009] Embodiment 3: The catalytic process of embodiment 1 or 2, wherein the regenerating comprises passing an inert gas through the reactor in two successive stages, including: i) a first, lower temperature stage comprising passing an inert gas through the reactor at an inert gas temperature of about 200° C. or less for a period of about 2 hours or longer; and ii) a second, higher temperature stage comprising passing an inert gas through the reactor at an inert gas temperature of about 250° C. or higher for a period of about 8 hours or longer.

[0010] Embodiment 4: The catalytic process of any one of embodiments 1-3, wherein the first lower temperature stage comprises one or more of: passing an inert gas through the reactor at an inert gas temperature of about 150° C. or less; passing an inert gas through the reactor at an inert gas temperature of about 40° C. to about 150° C.; passing an inert gas through the reactor at multiple inert gas temperatures ranging from about 40° C. to about 150° C., wherein the inert gas temperature is increased to each of the multiple inert gas temperatures at a rate of about 1 to about 5° C. / minute; passing the inert gas through the reactor for a period of about 4 hours or more; and passing the inert gas through the reactor for a period of about 2 to about 6 hours.

[0011] Embodiment 5: The catalytic process of any one of embodiments 1-4, wherein the second, higher temperature stage comprises one or more of: passing an inert gas through the reactor at an inert gas temperature of about 300° C. or less; passing an inert gas through the reactor at an inert gas temperature of about 250° C. to about 300° C.; passing an inert gas through the reactor for a period of about 14 hours or less; and passing an inert gas through the reactor for a period of about 8 to about 12 hours.

[0012] Embodiment 6: The catalytic process of any one of embodiments 1 to 5, wherein the transition from the first lower temperature stage to the second higher temperature stage is effected at a rate of about 1 to about 5° C. / min.

[0013] Embodiment 7: Inert gas flow rate is about 120 to about 300 cm 3 7. The catalytic process of any one of embodiments 1 to 6, wherein the reaction temperature is 1000° C. / min.

[0014] Embodiment 8: The catalytic process of any one of embodiments 1 to 7, further comprising periodically regenerating the modified alumina catalyst by stopping the feeding step and introducing an oxidizing gas into the reactor.

[0015] Embodiment 9: The catalytic process of any one of embodiments 1 to 8, wherein the oxidizing gas comprises oxygen at a gas temperature of about 300°C to about 450°C, and optionally the oxidizing gas is introduced for a period of 1 to 24 hours.

[0016] Embodiment 10: A modified alumina catalyst is used to convert about 80% by weight or more of 2-ethyl-1-butene to cis- or trans-3-methyl-2-pentene at a pressure of about 0.1 to 10 barg, a temperature of about 40 to 100° C., and a pressure of about 0.5 to 10 hours. -1 10. The catalytic process of any one of embodiments 1-9, wherein about 3 wt. % or less of the 1-hexene is converted to a different isomer under the same reaction conditions.

[0017] Embodiment 11: The catalytic process of any one of embodiments 1-10, further comprising feeding the effluent from the reactor to a distillation column to produce an overhead stream comprising linear alpha olefins and a bottoms stream comprising cis- or trans-3-methyl-2-pentene.

[0018] Embodiment 12: The catalytic process of any one of embodiments 1-11, wherein the overhead stream comprises about 99.5 wt.% or more 1-hexene and about 0.15 wt.% or less 2-ethyl-1-butene or an isomer thereof.

[0019] Embodiment 13: The catalytic process of any one of embodiments 1 to 12, wherein the modified alumina catalyst has from about 0.01 to about 0.5 mmol / g of Bronsted acid sites as measured by FTIR spectroscopy using pyridine as a probe molecule.

[0020] Embodiment 14: The catalytic process of any one of embodiments 1 to 13, wherein the modified alumina catalyst has from about 0.04 to about 0.2 mmol / g of Bronsted acid sites as measured by FTIR spectroscopy using pyridine as a probe molecule.

[0021] Embodiment 15: A catalytic process for the selective isomerization of 2-ethyl-1-butene in a linear alpha olefin product stream, comprising: feeding a linear alpha olefin product stream comprising at least one linear alpha olefin, such as 1-hexene and 2-ethyl-1-butene, to a reactor containing a modified alumina catalyst to isomerize at least a portion of the 2-ethyl-1-butene to cis- or trans-3-methyl-2-pentene; and withdrawing an effluent from the reactor containing less 2-ethyl-1-butene than the linear alpha olefin product stream, wherein the modified alumina catalyst has from about 0.01 to about 0.5 mmol / g of Bronsted acid sites as measured by FTIR spectroscopy using pyridine as the probe molecule, e.g., from about 0.04 to about 0.2 mmol / g of Bronsted acid sites as measured by FTRI spectroscopy using pyridine as the probe molecule.

[0022] Embodiment 16: A catalytic reactor system for the selective isomerization of 2-ethyl-1-butene in a linear alpha olefin product stream, comprising: a catalytic reactor containing a bed of a modified alumina catalyst, the modified alumina catalyst having from about 0.01 to about 0.5 mmol / g of Bronsted acid sites as measured by FTIR spectroscopy using pyridine as the probe molecule, for example, from about 0.04 to about 0.2 mmol / g of Bronsted acid sites as measured by FTIR spectroscopy using pyridine as the probe molecule; the catalytic reactor in fluid communication with a source of alpha olefin product comprising at least one linear alpha olefin, such as 1-hexene and 2-ethyl-1-butene. Optionally, the source of alpha olefin product is an effluent from an oligomerization reactor.

[0023] These and other features, aspects, and advantages of the present disclosure will become apparent from the following detailed description read in conjunction with the accompanying figures, which are briefly described below. The present disclosure includes any combination of two, three, four, or more features or elements described in the present disclosure, regardless of whether such features or elements are explicitly combined or otherwise recited in a specific exemplary implementation described herein. The present disclosure is intended to be read holistically such that any separable features or elements of the disclosure are to be viewed as combinable in any of its aspects and exemplary implementations, unless the context of the disclosure clearly dictates otherwise.

[0024] It is therefore understood that this brief summary is provided only for the purpose of summarizing some exemplary implementations so as to provide a basic understanding of some aspects of the present disclosure. Accordingly, it is understood that the exemplary implementations described above are merely examples and should not be construed to narrow the scope or spirit of the present disclosure in any way. Other exemplary implementations, aspects, and advantages will become apparent from the following detailed description, taken in conjunction with the accompanying figures, which illustrate, by way of example, the principles of some described exemplary implementations.

[0025] Having described aspects of the present disclosure in general terms above, reference is now made to the accompanying drawings, which are not necessarily drawn to scale. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a block diagram of an ethylene oligomerization system according to an exemplary implementation of the present disclosure. [Figure 2] FIG. 1 is a block diagram of an example of a process for purifying 1-hexene, according to an exemplary implementation of the present disclosure. [Figure 3] 1 is a graph showing the conversion of 1-hexene and 2E1B over time during the experiment of Example 1. [Figure 4] 1 graphically depicts the conversion of 1-hexene and 2E1B over time during the experiment of Example 2. [Figure 5]1 is a graph showing the conversion of 1-hexene and 2E1B over time during the experiment of Example 3. [Figure 6] 1 graphically depicts the FTIR spectrum for unmodified gamma alumina. DETAILED DESCRIPTION OF THE INVENTION

[0027] Certain implementations of the present disclosure will now be described more fully below with reference to the accompanying figures, in which some, but not all, implementations of the present disclosure are shown. Indeed, various implementations of the present disclosure may be embodied in many different forms and should not be construed as limited to the implementations set forth herein; rather, these exemplary implementations are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like reference characters refer to like elements throughout.

[0028] Unless otherwise specified or clear from the context, references to first, second, or the like should not be construed to imply a particular order. A feature described as being above another feature (unless otherwise specified or clear from the context) may instead be below, and vice versa; similarly, a feature described as being to the left of another feature may instead be to the right, and vice versa. Reference may also be made herein to quantitative measures, values, geometric relationships, or the like, and unless otherwise noted, any one or more, if not all, of these may be absolute or approximate to account for acceptable variations that may occur, such as those due to engineering tolerances or the like.

[0029] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other (e.g., a range of "up to 25 wt.%, or more specifically, 5 wt.% to 20 wt.%" includes the endpoints of the range "5 wt.% to 25 wt.%," and all intermediate values, etc.). "Combinations" are inclusive of blends, mixtures, alloys, reaction products, and the like.

[0030] The terms "about" or "approximately" are defined as close to what would be understood by one of ordinary skill in the art. In one non-limiting embodiment, the terms are defined as within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0031] As used herein, unless otherwise specified or clear from context, "or" of a set of operands is an "inclusive disjunction," whereby it is true if and only if one or more of the operands is true, as opposed to an "exclusive or," which is false when all of its operands are true. Thus, for example, "[A] or [B]" is true if [A] is true or if [B] is true, or if both [A] and [B] are true. Furthermore, the articles "a" and "an" mean "one or more" unless otherwise specified or clear from context that the singular form is referred to.

[0032] The present disclosure provides modified alumina catalysts having Bronsted acid sites that selectively isomerize 2-ethyl-1-butene to cis- or trans-3-methyl-2-pentene in the presence of 1-hexene to increase the purity level of 1-hexene produced by ethylene oligomerization. Without being bound by theory of operation, it is believed that the strength and density of Bronsted acid sites in the catalyst play an important role in selective isomerization. In certain embodiments, the modified alumina catalysts are characterized by having 0.01 to about 0.5 mmol / g of Bronsted acid sites, as measured by FTIR spectroscopy using pyridine as a probe molecule.

[0033] The present disclosure also provides a catalytic process for the selective isomerization of 2-ethyl-1-butene in a linear alpha olefin product stream that includes periodically regenerating a modified alumina catalyst using a non-oxidizing environment for a period and at a temperature that allows for continued use of the catalyst at peak performance levels.

[0034] Ethylene oligomerization process and system Linear alpha olefins (LAOs) have the chemical formula C x H 2x Linear alpha olefins are olefins with a molecular formula of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 12 20 ~C 24 , C 24 ~C 30 and C 20 ~C 30 It comprises the industrially important class of alpha-olefins, including higher blends of olefins. Linear alpha-olefins are useful intermediates for producing detergents, synthetic lubricants, copolymers, plasticizers, and many other important products.

[0035] Existing processes for producing linear alpha olefins typically rely on the oligomerization of ethylene. For example, linear alpha olefins can be prepared by catalytic oligomerization of ethylene in the presence of Ziegler-Natta type catalysts or non-Ziegler-Natta type catalysts.

[0036] The oligomerization can occur at a temperature of 10 to 200°C, such as 20 to 100°C, such as 50 to 90°C, such as 55 to 80°C, such as 60 to 70°C. The operating pressure can be 1 to 5 megapascals (MPa), such as 2 to 4 MPa. The process can be continuous, with an average residence time of 10 minutes to 20 hours, such as 30 minutes to 4 hours, such as 1 to 2 hours. The residence time can be selected to achieve the desired conversion with high selectivity.

[0037] The process can be carried out in a solution using an inert solvent that is advantageously non-reactive with the catalyst composition. Examples of suitable organic solvents include, but are not limited to, unsubstituted or halogen-substituted aromatic hydrocarbons such as toluene, benzene, xylene, monochlorobenzene, dichlorobenzene, and chlorotoluene; aliphatic paraffin hydrocarbons such as pentane, hexane, heptane, octane, nonane, and decane; alicyclic hydrocarbon compounds such as cyclohexane and decahydronaphthalene; and halogenated alkanes such as dichloroethane and dichlorobutane.

[0038] The process can be carried out in any reactor, such as a loop reactor, a plug-flow reactor, or a bubble column reactor. The oligomerization of ethylene is an exothermic reaction that can be cooled by an excess stream of ethylene. The gas leaving the top of the reactor can be cooled using a series of external coolers and condensers. The gas phase, after further cooling, can be recycled.

[0039] The bottoms stream leaving the bottom of the oligomerization reactor may contain active catalyst and unreacted ethylene. The reaction may be terminated to avoid undesirable side reactions by removing the catalyst components from the organic phase through extraction with a caustic aqueous phase. Contact with the caustic aqueous phase may result in the formation of unreacted inorganics corresponding to the catalyst components.

[0040] After passing through a catalyst removal system, the organic phase can be passed through a molecular sieve absorption bed and then fed to a distillation column to recover dissolved ethylene. The recovered ethylene can be recycled through an ethylene recycle loop, with the product being fed to an intermediate tank, after which the product can be fed to a separation section. In certain embodiments, linear alpha olefins produced from the reactor can be directed to a separation train.

[0041] 1, system 10 may include a reactor 12, a toluene (or other solvent) source 14, and a separation train 16. In a typical production mode, reactants 18, such as ethylene, a solvent, and a catalyst may be fed into reactor 12 to produce linear alpha olefins and various impurities, such as branched olefins and polymeric materials. After reaction, a bleed stream 20 may be directed into separation train 16, which separates the unreacted reactants, the produced linear alpha olefins, e.g., C4-C6, and the like. 20+ The linear alpha olefins may include olefins, a solvent, a catalyst, and various impurities. Separation train 16 may be configured to separate the linear alpha olefins from the solvent, catalyst, various impurities, and any unreacted ethylene. Separation train 16 may separate each linear alpha olefin, resulting in, for example, a C4 stream, a C6 stream, a C8 stream, etc. Separation train 16 may separate the linear alpha olefins into specific fractions, for example, C4-C 10 Distillate, C 11 ~C 17 Distillate, C 18 ~C 20 Distillate, C 20+ It may also be separated into fractions, or any other desired fractions.

[0042] The linear alpha olefin products can be isolated using a procedure including an aqueous caustic catalyst quench treatment followed by water washing and recovery of the final product by distillation. For example, a liquid product comprising a solvent (e.g., toluene) with dissolved ethylene can be fed to separation train 16 as described above. In the first column, unconsumed ethylene can be separated from the linear alpha olefin products and solvent. The ethylene can be recycled to the original reactor. The heavy fraction can be routed through a subsequent separation section where the heavy fraction is separated into various linear alpha olefin fractions (e.g., C8, C9, C10, C12, C14, C16, C18, C19, C20, C21, C22, C23, C24, C25, C26, C27, C28, C29, C30, C31, C32, C33, C34, C35, C36, C37, C38, C39, C40, C41, C42, C43, C44, C45, C46, ​​C47, C48, C49, C50, C51, C52, C53, C54, C55, C56, C57, C58, C59, C60, C61, C62, C63, C64, C65, C66, C67, C68, C69, C70, C71, C72, C73, C74, C75, C76, C77, C78, ​​C79, C71, C72, C73, C74, C75, C76, C77, C78, ​​C79, C80, C81, C82, C83, C84, C85, C86, C87, C88, C89, C91, C92, C93, C94, C95, C9 10 , >C 12 The solvent can also be recovered and recycled to the original reactor.

[0043] Polymer fouling in the reactor can occur during the oligomerization reaction process. Such fouling is typically detected by, for example, reduced effluent flow rates, reduced internal condenser performance, increased differential pressure at various locations within the reactor, etc. Such fouling can be treated by flushing the reactor with toluene or another solvent to remove the polymeric by-products. The flushed toluene containing the polymeric material can be directed into a separation train containing the linear alpha-olefin reaction products. The polymeric material is soluble in at least one of the linear alpha-olefins, and therefore the flashed toluene can exit the separation train essentially free of polymeric material and can be recycled to the original toluene source for subsequent reactor flushing.

[0044] Refining process for 1-hexene If the desired alpha olefin product in an ethylene oligomerization product stream is 1-hexene, which has a boiling point of 63.48° C., one example of a problematic impurity is 2-ethyl-1-butene, which has a boiling point of 64.67° C. See, for example, the composition of a typical 1-hexene product stream set forth in Table 1 below.

[0045] [Table 1]

[0046] However, 2-ethyl-1-butene can be converted to higher boiling isomers, such as cis- / trans-3-methyl-2-pentene, using an isomerization catalyst. This equilibrium-limited reaction is shown below:

[0047] [ka]

[0048] According to the present disclosure, in certain embodiments, separation train 16 of FIG. 1 includes at least one isomerization reactor and at least one distillation column. One example purification system is shown in FIG. 2. As shown, system 100 may include reactor 110 and separation unit 112. A first stream 101 containing 1-hexene and 2-ethyl-1-butene may be fed to reactor 110. In reactor 110, first stream 101 may contact an isomerization catalyst to form a second stream 102 containing 1-hexene and 3-methyl-2-pentene. Second stream 102 is typically fed to separation unit 112. In separation unit 112, the second stream may be separated to form a third stream containing 1-hexene and a fourth stream containing 3-methyl-2-pentene.

[0049] The feed stream to reactor 110 can vary in composition but is typically at least 96 wt % or at least 98 wt % 1-hexene (e.g., from about 96 wt % to about 98.5 wt % or from about 98 wt % to about 98.5 wt %) and at least 0.5 wt % or at least 0.8 wt % 2-ethyl-1-butene (e.g., from about 0.5 wt % to about 1.5 wt % or from about 0.8 wt % to about 1.2 wt %).

[0050] Reactor 110 may be any suitable reactor, including, but not limited to, a fixed bed reactor, a moving bed reactor, a trickle bed reactor, a rotating bed reactor, a slurry reactor, or a fluidized bed reactor. In certain embodiments, reactor 110 may be a fixed bed reactor and may include a stationary bed containing an isomerization catalyst such that first stream 101 may pass through and / or over the stationary bed. In reactor 110, stream 101 may contact the isomerization catalyst to selectively isomerize 2-ethyl-1-butene in the first stream to 3-methyl-2-pentene.

[0051] The first stream 101 may be, for example, at i) a temperature of 40°C to 100°C, or 40°C to 60°C, or at least one of, equal to, or between any two of 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 65, 70, 75, 80, 85, 90, 95, and 100°C; ii) a pressure of 0.1 barg to 10 barg, or at least one of, equal to, or between any two of 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 barg; and / or iii) a pressure of 0.5 h -1 ~10h -1 , or 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10h -1 or any combination thereof.

[0052] The conversion of 2-ethyl-1-butene for the isomerization reaction can be from 50% to 100% by weight, for example, from 70% to 100%, or from 80% to 99.9%, or at least any one of, equal to, or between any two of 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 97.5, 97.6, 97.8, 98, 98.5, 99, 99.5, 99.7, 99.8, 99.9, and 100%. The total selectivity for 3-methyl-2-pentene for the isomerization reaction can be 50% to 100% by weight, or at least any one of, equal to, or between any two of 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 99, and 100% by weight. The 1-hexene conversion during the isomerization reaction can be less than 10% by weight, or less than 5%, or less than 3%, or less than 2.5%, or less than 2.0%, or less than 1.5%, or less than 1.0%, or less than 0.5%, for example, 0.5% to 10%, or less than 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, and 10% by weight, or equal to, or between any two of these.

[0053] The type of distillation column (e.g., separation unit 112) can vary, examples of which include columns with bubble cap trays, valve trays, or sieve trays. The use of an isomerization catalyst as contemplated in this disclosure can reduce the number of stages that might otherwise be required to achieve very high purity for certain linear alpha olefins, such as 1-hexene. For example, in certain embodiments, the number of distillation stages required to achieve a high degree of linear alpha olefin purity (e.g., about 99.5 wt. % or higher) is about 150 or fewer, or about 120 or fewer (e.g., from about 80 to about 150 stages).

[0054] The second stream 102 can be separated by distillation in a distillation column to form a third stream 103 containing 1-hexene and a fourth stream containing 3-methyl-2-pentene. Operating conditions of the distillation column for separating the second stream 102 can include: i) a temperature of 50°C to 100°C, or 55°C to 75°C, or at least one of, equal to, or between any two of: 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100°C; and / or ii) a pressure of 0 barg to 3 barg, or at least one of, equal to, or between any two of: 0, 0.01, 0.1, 0.5, 1, 1.5, 2, 2.5, and 3 barg. The boiling points of cis and trans 3-methyl-2-pentene are sufficiently different from 1-hexene that 3-methyl-2-pentene can be separated from 1-hexane through distillation of the second stream. In certain embodiments, third stream 103 can be formed as an overhead product of the distillation column, and fourth stream 104 can be formed as a bottom product of the distillation column.

[0055] Alternatively, instead of using a catalyst bed upstream of the distillation column shown in Figure 2, an outer reactor containing catalyst can be positioned to receive the feed from a stage of the distillation column, and the effluent from the side reactor can be fed back to a stage of the distillation column. One or more side reactors can be operated, for example, as either a plug flow reactor (otherwise known as a tubular reactor) or a continuous stirred tank reactor (CSTR), and can be operated at temperatures and pressures independent of the distillation column operating temperature and pressure. The impurity-containing 1-hexene feed can be fed to the tubular reactor in either upflow or downflow mode.

[0056] Isomerization Catalyst The isomerization catalyst is capable of selectively isomerizing 2-ethyl-1-butene in the presence of 1-hexene (and hexane, and, if present, other isomer(s) of 1-hexene) to form 3-methyl-2-pentene. In some embodiments, the catalyst material is an activated alumina material, such as high bulk density gamma-alumina, low or medium bulk density large pore gamma-alumina, and low bulk density large pore boehmite and gamma-alumina.

[0057] High surface area alumina materials, sometimes called "gamma alumina" or "activated alumina," are typically 60 m 2 / g, often about 200m 2 / g or greater. Such activated aluminas are typically mixtures of gamma and delta phases of alumina, but may also contain significant amounts of eta, kappa, and theta alumina phases. "BET surface area" has its ordinary meaning, referring to the Brunauer, Emmett, Teller method for determining surface area by N2 adsorption.

[0058] In one particular embodiment, the alumina material comprises: i) 200m 2 / g~550m 2 / g, or 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540 and 550m 2 / g; ii) an average particle size of 1 mm to 8 mm, or at least one of, equal to, or between any two of 1, 2, 3, 4, 5, 6, 7, and 8 mm; and / or iii) an average crush strength of 0.5 to 40 kg, or at least one of, equal to, or between any two of 0.5, 1, 5, 10, 15, 20, 25, 30, 35, and 40 kg, or any combination thereof.

[0059] Certain useful alumina materials are commercially available as alumina materials that have been chemically modified to increase the presence of acidic functional groups. As used herein, "modified alumina" refers to an alumina material that has been chemically modified to enhance the acid functionality of the alumina. A non-limiting example of a commercially available modified alumina is SELEXSORB® CD, available from BASF. Additionally, there is a known process for preparing γ-Al2O3 that is rich in Bronsted acid sites and has reduced Lewis acid sites, using a sol-gel method with NHBF4 as a modifier. See J. Phys. Chem. C2014, 118, 12, 6226-6234.

[0060] The alumina materials utilized in this disclosure are characterized by the presence of sufficient Bronsted acid sites for the adsorption and isomerization of 2-ethyl-1-butene. For example, in certain embodiments, the alumina materials have at least 0.01 mmol / g of Bronsted acid sites (e.g., at least 0.02, or at least 0.03, or at least 0.04 mmol / g), but typically have less than 0.5 mmol / g of Bronsted acid sites (e.g., less than 0.4, or less than 0.3, or less than 0.2, or less than 0.1, or less than 0.09 mmol / g). If the catalyst contains a high density of Bronsted acid sites, the catalyst may be more prone to nonselective isomerization, which may result in undesirable 1-hexene conversion. The concentration of Bronsted acid sites can be measured by FTIR spectroscopy using pyridine as a probe molecule, as described in the experiments. The nature of the Bronsted acid sites of the modified alumina catalyst is weak, i.e., the pyridine probe molecules held by the Bronsted sites may be desorbed at or above 150°C under vacuum.

[0061] As noted above, in certain embodiments, an isomerization catalyst can be characterized based on the extent to which it converts an undesired first isomer to a second isomer. For example, in certain embodiments, an isomerization catalyst can be used to convert about 80% by weight or more (e.g., about 85% by weight or more, or about 90% by weight or more, or about 95% by weight or more) of 2-ethyl-1-butene to the second isomer in about 1 hour at a pressure of about 0.1 to 10 barg, a temperature of about 40 to 100° C., and a reaction time of about 0.5 to 10.0 hours. -1 In some embodiments, about 3 wt. % or less (e.g., about 2 wt. % or less, or about 1 wt. % or less) of the 1-hexene is converted to a different isomer under the same reaction conditions described above.

[0062] The use of the isomerization catalysts contemplated herein can enable the purification of 1-hexene or other linear alpha-olefins to a purity of about 99.5 wt.% or higher in the overhead stream of the distillation column. In certain embodiments, the overhead product stream from the distillation column is characterized by a very low purity content of branched olefins such as 2-ethyl-1-butene, for example, about 0.3 wt.% or less, or about 0.2 wt.% or less, or about 0.15 wt.% or less. When the targeted linear alpha-olefin is 1-hexene, in certain embodiments, the overhead product stream is also characterized by a very low n-hexene content, for example, about 200 ppm or less, or about 150 ppm or less n-hexene.

[0063] Catalyst regeneration Surprisingly, it has been discovered that periodically regenerating the modified alumina catalyst described herein can result in robust catalytic performance that can be sustained for thousands of hours in certain embodiments. Typically, the regeneration process involves stopping the supply of the linear alpha olefin product stream to the catalytic reactor and introducing a non-oxidizing environment into the reactor at intervals of about 200 hours or less on stream. In certain embodiments, the reactor is subjected to the non-oxidizing environment for a period of about 15 hours or longer, the non-oxidizing environment having a temperature of about 250°C or higher for at least a portion of that period. As described in the experiments below, such a regeneration process can be used repeatedly to return the catalyst to the same performance level as a fresh catalyst.

[0064] The time interval between regeneration steps can vary and depends, in part, on the moisture level in the feed stream. Higher levels of moisture in the feed often require shorter intervals between regeneration processes. For example, a low-moisture feed, having less than about 10 ppm water, can allow for longer intervals between regeneration steps, such as interval periods of greater than about 120 hours, greater than about 140 hours, greater than about 160 hours, or greater than about 180 hours (e.g., about 150 to about 300 hours, or even longer). Conversely, higher levels of moisture in the feed (e.g., about 30 ppm or higher, e.g., about 30 to about 80 ppm) can result in shorter intervals, such as less than about 150 hours, less than about 130 hours, less than about 110 hours, or less than about 100 hours (e.g., about 80 to about 150 hours).

[0065] A non-oxidizing environment is typically any environment that is inert to the modified alumina catalyst. Examples include a vacuum environment or an inert gas environment, such as a nitrogen or noble gas environment. A non-oxidizing environment is substantially or completely free of oxygen.

[0066] In certain embodiments, the regeneration process utilizing a non-oxidizing environment is carried out in successive stages. For example, the regeneration process may include a first lower temperature stage comprising passing an inert gas through the reactor at an inert gas temperature of about 200° C. or less for a period of about 2 hours or longer. This lower temperature regeneration step is useful for purging water and any residual physisorbed hydrocarbons from the catalyst bed.

[0067] In certain embodiments, the lower temperature stage may include passing an inert gas through the reactor at an inert gas temperature of about 150°C or less, e.g., about 40°C to about 150°C. The lower temperature stage itself may include multiple stages at various temperatures, e.g., two or three temperature levels within the temperature ranges described above. The total regeneration time for the lower temperature stage may vary but is typically about 4 hours or longer. In certain embodiments, the total regeneration time for the lower temperature stage is about 2 to about 6 hours, or about 4 to about 6 hours. Higher temperatures usually allow for shorter periods for this regeneration step. Thus, one skilled in the art may choose to use a lower temperature in combination with a longer period, or may choose a higher temperature and a shorter period within the ranges described above. The inert gas flow rate during this stage is typically about 120 to about 300 cm3. 3 / min, for example, about 150 to about 250 cm 3 / min.

[0068] In certain embodiments, the regeneration process may include a second, higher temperature step, such as a step comprising passing an inert gas through the reactor for a period of about 8 hours or longer at an inert gas temperature of about 250° C. or higher. This higher temperature step may advantageously result in further removal of compounds adsorbed on the Bronsted acid sites.

[0069] In certain embodiments, the higher temperature stage may include passing an inert gas through the reactor at an inert gas temperature of about 300°C or less, e.g., about 250°C to about 300°C. The higher temperature stage itself may include multiple stages at various temperatures, e.g., two or three temperature levels within the temperature ranges described above. The total regeneration time for the higher temperature stage may vary but is typically about 14 hours or less. In certain embodiments, the total regeneration time for the lower temperature stage is about 8 to about 14 hours, or about 10 to about 12 hours. Higher temperatures usually allow for shorter periods for this regeneration step. Thus, one skilled in the art may choose to use lower temperatures in combination with longer periods, or may choose higher temperatures and shorter periods within the ranges described above. The inert gas flow rate during this stage is typically about 120 to about 300 cm3. 3 / min, for example, about 150 to about 250 cm 3 / min.

[0070] The non-oxidizing environment may become insufficient to fully regenerate the catalyst after a certain time during flow due to carbon / coke accumulation on the catalyst surface. Therefore, in certain embodiments, the regeneration process further includes periodically introducing an oxidizing gas, such as air or purified oxygen, into the reactor. In certain embodiments, the oxidizing gas is introduced at a gas temperature of about 300°C to about 450°C for a period of 1 hour to 24 hours or longer (e.g., at least 1 hour or longer, at least 10 hours or longer, at least 15 hours or longer, or at least 20 hours or longer). The regeneration time to remove carbonaceous species depends on the temperature and concentration of oxygen. Regeneration in an oxidizing environment can be applied when regeneration in a non-oxidizing environment does not improve catalyst performance to the same level as that of a fresh catalyst. That is, in plant operation, such oxidative regeneration can be applied when catalyst performance after non-oxidative regeneration quickly declines to a predetermined threshold level of performance, as determined by conversion selectivity or cycle length.

[0071] It is advantageous to avoid subjecting the catalyst material to sudden temperature changes during the regeneration process, which may lead to degradation of the catalyst structure. Thus, when it is desired to change the regeneration temperature, such changes are typically achieved using relatively small temperature ramp rates, for example, increasing or decreasing the temperature at a rate of about 1 to about 5°C / min. [Example]

[0072] experiment The following examples utilize Selexsorb® CD catalyst commercially available from BASF Corp. Table 2 below provides certain characteristics of the catalyst material.

[0073] [Table 2]

[0074] The FTIR spectroscopy measurement process used was as follows: The alumina catalyst was crushed into a fine powder and pressed (under 10 tons of pressure) into a 0.65 cm diameter (surface area 1.33 cm 2 ) and weight 0.02 g (i.e., 0.015 g / cm 2 ) into free-standing thin wafers. Sample wafers were heated under vacuum or in a stream of N2 (depending on whether the catalyst was fresh or used) up to 280 °C for 4 to 24 hours. The catalyst wafers were cooled and exposed to pyridine vapor at 100 °C for 30 minutes, then desorbed under vacuum at 100 °C. Infrared spectra of the pretreated and pyridine-adsorbed samples were obtained at room temperature using a Perkin-Elmer Spectrum One FTIR spectrometer at 4 cm -2 The image was recorded as the average of 16 scans.

[0075] To determine the acid sites, the Beer-Lambert-Bouguer law is A=ε×Cs Apply in the form where Cs is the concentration of Bronsted acid sites in μmol / g, A is the integrated absorbance of the corresponding infrared band in cm / g, normalized to the catalyst wafer density, and ε is the integrated molar absorption coefficient (see Gabrienko, AA, et al., Journal of Physical Chemistry, 122, p. 25386, 2018). The ε values ​​of 1.67 cm / μmol and 2.22 cm / μmol for pyridine adsorbed on Bronsted acid sites and Lewis acid sites were taken from Emeis, CA, Journal of Catalysis, 141, p. 347, 1993.

[0076] [Example 1] Selexsorb® CD catalyst (size 1.4-1.7 mm, perfect sphere, 17.56 gm, 25 cm 3 ) was charged into a 1-inch OD stainless steel tubular reactor and glass inserts were added to both ends of the catalyst bed. The catalyst was heated under a N flow (170 cm 3 The catalyst bed was dried at 45°C under a constant temperature (°C / min) for 2 hours at 45°C, then heated to 150°C at 5°C / min and held for 2 hours, then heated to 280°C at 5°C / min and held for 12 hours. The catalyst bed temperature was cooled to 45°C and the N flow was stopped for introduction of the feed into the reactor.

[0077] The 1-hexene feed was dried using molecular sieve 4 A. The catalytic test was initiated by flowing the 1-hexene feed at approximately 0.4 mL / min (the feed rate was varied at the start and is shown in Figure 3), with a catalyst bed temperature of 45°C and an inlet pressure of 1.5 psig.

[0078] Table 3 below shows the composition of the feed and product streams (with a time on stream of 56.3 hours). The 2E1B and 1-H conversions were found to be 98.73% and 0.09%. 2E1B was mostly converted to cis- and trans-3-methyl-2-pentene.

[0079] The 2E1B conversion decreased with time on stream. The catalyst was first purified by flowing N2 (170 cm) at 45 °C for 2 hours. 3 The catalyst bed was purged (5°C / min) and then regenerated by heating at 5°C / min to 150°C, held for 2 hours, then heating at 5°C / min to 280°C, held for 12 hours, after which it was cooled to 45°C and the feed was reintroduced into the reactor. The total regeneration time was 16 hours, with 170 cm 3 There were three temperature steps under N2 flow / min.

[0080] The regeneration process was repeated periodically as catalyst performance deteriorated. Most of the regeneration steps in this example were performed after 300 hours on stream. As shown graphically in Figure 3, catalyst performance deteriorated over time, and the periodic regeneration process failed to return the catalyst to its original performance level.

[0081] [Table 3]

[0082] [Example 2] The experiments of Example 1 were carried out with a slightly different catalyst loading (Selexsorb® CD; 24.34 g; 36 cm 3 ) and using the same catalyst drying process as in Example 1.

[0083] Compared to the catalyst regeneration in Example 1, a longer duration of N flow with additional steps was used in Example 2. The catalyst was first regenerated with N flow (170 cm) at 45° C. for 2 hours. 3 The catalyst bed was purged (5°C / min) and then regenerated by heating at 5°C / min to 60°C and holding for 12 hours, then heating at 5°C / min to 150°C and holding for 4 hours, then heating at 5°C / min to 280°C and holding for 12 hours, after which it was cooled to 45°C and reintroduced to the reactor. The total regeneration time was approximately 30 hours, with 170 cm 3 There were four temperature steps under N2 flow at 1000 rpm.

[0084] Table 4 below shows the composition of the feed and product streams (with a time on stream of 126.6 hours). The 2E1B and 1-H conversions were found to be 97.47% and 0.04%. 2E1B was mostly converted to cis- and trans-3-methyl-2-pentene.

[0085] In Example 2, catalyst life increased with increasing duration of N flow, along with shorter durations between addition and regeneration steps (relative to Example 1). Catalyst performance was maintained over time, as shown graphically in Figure 4. Most of the regeneration steps were performed after 200 hours or less of time on stream.

[0086] [Table 4]

[0087] [Example 3] Selexsorb® CD catalyst (size 2.8-3.2 mm, perfect sphere, 6.1 g, 9 cm 3 ) was loaded into a 0.5 inch OD stainless steel tubular reactor and glass inserts were added to both ends of the catalyst bed. The catalyst was then heated under a N flow (200 cm 3 The catalyst bed was dried at 45°C under a constant flow rate (r / min) for 2 hours at 45°C, then heated at 2°C / min to 150°C and held for 2 hours, then heated at 2°C / min to 280°C and held for 12 hours. The catalyst bed temperature was cooled to 45°C and the N flow was stopped to charge the reactor with the feed.

[0088] The 1-hexene feed was dried using a nitrogen gas purge for 0.5 hours. The catalytic test began by flowing the 1-hexene feed at approximately 0.1 mL / min, with a catalyst bed temperature of 45°C and an inlet pressure of 1.5 psig. Table 5 below shows the composition of the feed and product streams (with a flow time of 192 hours). The 2E1B and 1-H conversions were found to be 97.72% and 0.01%. 2E1B was mostly converted to cis- and trans-3-methyl-2-pentene.

[0089] The 2-ethyl-1-butene conversion decreased with time on stream. The catalyst was first purified by flowing N2 (200 cm) at 45 °C for 2 h. 3 The catalyst bed was purged (2°C / min) and then periodically regenerated by heating at 2°C / min to 150°C, holding for 2 hours, then heating at 2°C / min to 280°C, holding for 12 hours, after which it was cooled to 45°C and reintroduced the feed to the reactor. The total N2 regeneration time was approximately 16 hours, with 200 cm3 3 There were three temperature steps under N2 flow at 1924 h. The catalyst was also subjected to an air regeneration step once during the experiment, at 1924 h. The air regeneration consisted of (a) stopping the 1-hexene feed flow and passing N2 gas through to purge the hydrocarbon for approximately 1 h; (b) passing air at 200 cm3. 3 / min, (b) ramping the catalyst bed temperature to 110°C (5°C / min) and holding for 2 hours; and (c) ramping the temperature to 350°C (1°C / min) and holding for 5 hours. The catalyst bed temperature was allowed to cool to room temperature and N was purged before catalytic testing. The air regeneration step was able to return the catalyst to the same performance level as fresh catalyst after catalyst performance had begun to deteriorate following repeated N regenerations.

[0090] In Example 3, catalyst life increased with frequent catalyst N regeneration (relative to Example 1). As shown graphically in Figure 5, catalyst performance was maintained over time with no visible performance degradation (with normal regeneration) for periods of more than 2500 hours. Most of the regeneration steps were performed after 200 hours or less of time on stream. Table 6 below presents the frequency and type of regeneration used for each regeneration step.

[0091] [Table 5]

[0092] [Table 6]

[0093] [Example 4] In a separate experiment, a fresh sample of Selexsorb® CD was analyzed using FTIR spectroscopy, using pyridine as a probe molecule to measure Bronsted and Lewis acid sites. The spent catalyst from Example 2 was also subjected to the same acid site analysis as the comparative example after approximately 850 hours of catalytic testing at 280°C with frequent N2 regeneration. The results are set forth in Table 7 below. Each sample was pretreated as shown in Table 7 before analysis. As shown, longer N2 treatment of the spent catalyst can restore Bronsted acid sites, which is consistent with the results set forth in Examples 1-3.

[0094] [Table 7]

[0095] [Comparative Example 1] The experiment of Example 1 was repeated using different alumina catalysts: Selexsorb® CDL, available from BASF, and Actisorb® 100-1, available from Clariant Ltd. Unlike Selexsorb® CD, neither of these adsorbents is believed to have Bronsted acid sites within the ranges described in this disclosure.

[0096] Selexsorb® CDL and Actisorb® 100-1 were catalytically tested using the same catalyst pretreatment and test conditions as described in Example 1. The results are presented below in Table 8. As shown, the alumina-based catalyst also failed to convert significant amounts of 2E1B to cis- and trans-3-methyl-2-pentene.

[0097] [Table 8]

[0098] Comparative Example 2 The unmodified gamma alumina was analyzed using FTIR spectroscopy using pyridine as a probe molecule to measure Bronsted and Lewis acid sites as described above. The FTIR spectrum is shown in Figure 6 and shows a peak at 1450 cm -1 A peak appears at 1545 cm (Lewis acid site). -1 There was no peak (characteristic peak for Brønsted acid sites) around this area, which is consistent with the idea that the presence of Brønsted acid sites is important for the strong 2E1B conversion performance.

[0099] In general, the present invention may alternately comprise, consist of, or consist essentially of any suitable components disclosed herein. The present invention may additionally or alternatively be formulated to be free or substantially free of any component, material, ingredient, adjuvant, or species used in prior art compositions or that are not normally necessary to achieve the function and / or purpose of the present invention.

[0100] Many modifications and other implementations of the present disclosure will come to mind to one skilled in the art to which this disclosure pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. It is to be understood, therefore, that the disclosure is not limited to the particular implementations disclosed herein, and that modifications and other implementations are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. 1. A catalytic process for the selective isomerization of 2-ethyl-1-butene in a linear alpha olefin product stream, comprising: feeding a linear alpha olefin product stream comprising at least one linear alpha olefin, such as 1-hexene and 2-ethyl-1-butene, to a reactor containing a modified alumina catalyst to isomerize at least a portion of the 2-ethyl-1-butene to cis- or trans-3-methyl-2-pentene, wherein the period of time during which the feeding occurs is the flow time; withdrawing an effluent from said reactor containing less 2-ethyl-1-butene than said linear alpha olefin product stream; periodic regeneration of the modified alumina catalyst by stopping the feeding step and introducing a non-oxidizing environment into the reactor for a flow time interval of about 200 hours or less, wherein the reactor is subjected to the non-oxidizing environment for a period of about 15 hours or longer, the non-oxidizing environment having a temperature of about 250° C. or greater for at least a portion of that period; A catalytic process comprising:

2. 10. The catalytic process of claim 1, wherein the non-oxidizing environment comprises a vacuum environment or an inert gas environment such as a nitrogen or noble gas environment.

3. 3. The catalytic process of claim 1 or 2, wherein the regeneration step comprises passing the inert gas through the reactor in two successive stages comprising: i) a first lower temperature stage comprising passing the inert gas through the reactor at an inert gas temperature of about 200° C. or less for a period of about 2 hours or longer; and ii) a second higher temperature stage comprising passing the inert gas through the reactor at an inert gas temperature of about 250° C. or higher for a period of about 8 hours or longer.

4. the first lower temperature stage comprising: passing the inert gas through the reactor at an inert gas temperature of about 150°C or less; passing the inert gas through the reactor at an inert gas temperature of about 40°C to about 150°C; passing the inert gas through the reactor at multiple inert gas temperatures ranging from about 40°C to about 150°C, wherein the inert gas temperature is increased to each of the multiple inert gas temperatures at a rate of about 1 to about 5°C / minute; passing the inert gas through the reactor for a period of about 4 hours or longer; and passing the inert gas through the reactor for a period of about 2 to about 6 hours.

4. The catalytic process of claim 3, comprising one or more of:

5. the second, higher temperature stage comprising: passing the inert gas through the reactor at an inert gas temperature of about 300°C or less; passing the inert gas through the reactor at an inert gas temperature of about 250°C to about 300°C; passing the inert gas through the reactor for a period of about 14 hours or less; and passing the inert gas through the reactor for a period of about 8 to about 12 hours.

4. The catalytic process of claim 3, comprising one or more of:

6. 6. The catalytic process of any one of claims 3 to 5, wherein the transition from the first lower temperature stage to the second higher temperature stage is effected at a rate of about 1 to about 5°C / min.

7. The inert gas flow rate is about 120 to about 300 cm ３ 7. The catalytic process of claim 3, wherein the reaction temperature is 1000° C. / min.

8. 8. The catalytic process of any one of claims 1 to 7, further comprising periodically regenerating the modified alumina catalyst by stopping the feeding step and introducing an oxidizing gas into the reactor.

9. 9. The catalytic process of claim 8, wherein the oxidizing gas comprises oxygen at a gas temperature of about 300° C. to about 450° C., and optionally the oxidizing gas is introduced for a period of 1 to 24 hours.

10. The modified alumina catalyst converts about 80 wt. % or more of 2-ethyl-1-butene to cis- or trans-3-methyl-2-pentene at a pressure of about 0.1 to 10 barg, a temperature of about 40 to 100° C., and a reaction time of about 0.5 to 10 hours. －１ 10. The catalytic process of claim 1, wherein about 3 wt. % or less of the 1-hexene is converted to a different isomer under the same reaction conditions.

11. 11. The catalytic process of any one of claims 1 to 10, further comprising feeding the effluent from the reactor to the distillation column to produce an overhead stream comprising the linear alpha olefins and a bottoms stream comprising cis- or trans-3-methyl-2-pentene.

12. 12. The catalytic process of claim 11, wherein the overhead stream comprises about 99.5 wt.% or greater 1-hexene and about 0.15 wt.% or less 2-ethyl-1-butene or an isomer thereof.

13. 13. The catalytic process of any one of claims 1 to 12, wherein the modified alumina catalyst has from about 0.01 to about 0.5 mmol / g of Bronsted acid sites as measured by FTIR spectroscopy using pyridine as a probe molecule.

14. 14. The catalytic process of claim 13, wherein the modified alumina catalyst has from about 0.04 to about 0.2 mmol / g of Bronsted acid sites as determined by FTIR spectroscopy using pyridine as a probe molecule.

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