Method 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] This disclosure relates to a method for purifying a stream of linear alpha-olefin products from an oligomerization reaction. [Background technology]

[0002] Linear olefins are a class of hydrocarbons useful as raw materials in the petrochemical industry, and among these linear alpha-olefins, unbranched olefins, in which their 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, i.e., they can be oxidized to provide synthetic fatty acids, particularly those with an odd number of carbon atoms, which are 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 and subsequent sulfonation of benzene and linear olefins. Another important application 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-olefin having an even number of carbon atoms. The oligomerization process for ethylene mainly utilizes organoaluminum compounds or transition metals as catalysts. The oligomerization method 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 the various fractions of linear alpha-olefins. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] It is desirable to purify the alpha-olefin product from oligomerization reactions to a very high purity level, such as above 99.5% by weight. Achieving such high purity can be challenging when using conventional separation processes due to the presence of impurities whose boiling points are very close to those of the target alpha-olefin product. Improvements to the separation processes for such products remain a need in this field. [Means for solving the problem]

[0005] (Summary of the invention) An exemplary implementation of the present disclosure relates to a process for purifying a linear alpha-olefin product stream, comprising the use of modified alumina to isomerize 2-ethyl-1-butene to an isomer that is more readily removed from 1-hexane by distillation. The use of such a modified alumina catalyst can improve the separation efficiency of the distillation column and enable the purification of the target linear alpha-olefin to a very high purity level. The disclosure also provides a catalytic process for the selective isomerization of 2-ethyl-1-butene in a linear alpha-olefin product stream, comprising periodically regenerating the modified alumina catalyst using a non-oxidizing environment for a period and temperature at which the catalyst can be continuously used at peak performance levels.

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

[0007] Embodiment 1: A catalytic process for selective isomerization of 2-ethyl-1-butene in a linear alpha-olefin product stream, wherein 1-hexe Nna any at least one linear alphaolefin and 2-ethyl-1-buteneA process for isomerizing at least a portion of 2-ethyl-1-butene to cis- or trans-3-methyl-2-pentene by feeding a linear alpha-olefin product stream containing the same to a reactor containing a modified alumina catalyst, wherein the period during which the feeding is carried out is the residence time, a feeding step; a step of withdrawing an effluent from a reactor containing less 2-ethyl-1-butene than the linear alpha-olefin product stream; and a step of periodically regenerating the modified alumina catalyst by stopping the feeding step and introducing a non-oxidizing environment into the reactor at intervals of a residence time 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, and the non-oxidizing environment has a temperature of about 250 °C or higher at at least a portion of that period, a regeneration step, a catalyst process.

[0008] Embodiment 2: The catalyst process according to Embodiment 1, wherein the non-oxidizing environment includes a vacuum environment or an inert gas environment such as a nitrogen or noble gas environment.

[0009] Embodiment 3: The regeneration step includes a first lower temperature stage including passing an inert gas through the reactor for a period of about 2 hours or longer at an inert gas temperature of about 200 °C or lower; and a second higher temperature stage including 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, the catalyst process according to Embodiment 1 or 2 including a step of passing an inert gas through the reactor in two consecutive stages.

[0010] Embodiment 4: The first lower temperature stage includes one or more of the following: 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 a number of inert gas temperatures ranging from about 40 °C to about 150 °C, where the inert gas temperature is increased to each of the number of inert gas temperatures at a rate of about 1 to about 5 °C per minute; passing an inert gas through the reactor for about 4 hours or a longer period; and passing an inert gas through the reactor for a period of about 2 to about 6 hours. The catalyst process according to any one of Embodiments 1 to 3.

[0011] Embodiment 5: The second higher temperature stage includes one or more of the following: 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 about 14 hours or a shorter period; and passing an inert gas through the reactor for a period of about 8 to about 12 hours. The catalyst process according to any one of Embodiments 1 to 4.

[0012] Embodiment 6: The transition from the first lower temperature stage to the second higher temperature stage is caused at a rate of about 1 to about 5 °C per minute. The catalyst process according to any one of Embodiments 1 to 5.

[0013] Embodiment 7: The inert gas flow rate is about 120 to about 300 cm 3 / min. The catalyst process according to any one of Embodiments 1 to 6.

[0014] Embodiment 8: The catalyst process according to any one of Embodiments 1 to 7, further including periodically regenerating the modified alumina catalyst by stopping the supply process and introducing an oxidizing gas into the reactor.

[0015] Embodiment 9: A catalytic process according to any one of Embodiments 1 to 8, wherein the oxidizing gas contains oxygen at a gas temperature of approximately 300°C to approximately 450°C, and the oxidizing gas is optionally introduced over a period of 1 to 24 hours.

[0016] Embodiment 10: The modified alumina catalyst is converted 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 about 0.5 to 10 hours. -1 The catalytic process according to any one of Embodiments 1 to 9, wherein conversion is possible at a liquid-space velocity, and about 3% by weight or less of 1-hexene is converted to different isomers under the same reaction conditions.

[0017] Embodiment 11: The catalytic process according to any one of Embodiments 1 to 10, further comprising supplying effluent from a reactor to a distillation column to generate a top flow containing linear alphaolefins and a bottom flow containing cis- or trans-3-methyl-2-pentene.

[0018] Embodiment 12: The catalytic process according to any one of Embodiments 1 to 11, wherein the top flow of the column contains about 99.5% by weight or more of 1-hexene and about 0.15% by weight or less of 2-ethyl-1-butene or its isomers.

[0019] Embodiment 13: A catalytic process according to any one of Embodiments 1 to 12, wherein the modified alumina catalyst has a Brønsted acid moiety of about 0.01 to about 0.5 mmol / g of catalyst, as measured by FTIR spectroscopy using pyridine as a probe molecule.

[0020] Embodiment 14: A catalytic process according to any one of Embodiments 1 to 13, wherein the modified alumina catalyst has a Brønsted acid moiety of approximately 0.04 to approximately 0.2 mmol / g of catalyst, as measured by FTIR spectroscopy using pyridine as a probe molecule.

[0021] Embodiment 15: A catalytic process for selective isomerization of 2-ethyl-1-butene in a linear alpha-olefin product stream, wherein 1-hexe Nna any at least one linear alphaolefin and 2-ethyl-1-butene A catalytic process comprising: feeding a linear alpha-olefin product stream containing a modified alumina catalyst into a reactor containing a modified alumina catalyst to isomerize at least a portion of 2-ethyl-1-butene to cis- or trans-3-methyl-2-pentene; and drawing out effluent from a reactor containing less 2-ethyl-1-butene than the linear alpha-olefin product stream, wherein the modified alumina catalyst has approximately 0.01 to approximately 0.5 mmol / g of Brønsted acid moieties as measured by FTIR spectroscopy using pyridine as a probe molecule, for example, approximately 0.04 to approximately 0.2 mmol / g of Brønsted acid moieties as measured by FTRI spectroscopy using pyridine as a probe molecule.

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

[0023] These and other features, aspects, and advantages of the Disclosure will become apparent from reading the detailed description below in conjunction with the accompanying diagrams briefly described below. The Disclosure includes any combination of two, three, four, or more features or elements described herein, whether such features or elements are expressly combined or otherwise enumerated in specific exemplary implementations described herein. The Disclosure is intended to be read holistically so that any separable feature or element of the Disclosure should be seen as combinable in any aspect or exemplary implementation, unless the context of the Disclosure otherwise expresses otherwise.

[0024] Therefore, it is understood that this brief summary is provided solely for the purpose of summarizing some exemplary implementations to provide a basic understanding of some aspects of the present disclosure. Accordingly, it is understood that the above-mentioned exemplary implementations are merely examples and should not be construed as narrowing 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, which should be interpreted in conjunction with the accompanying diagrams illustrating some of the principles of the described exemplary implementations.

[0025] The aspects of this disclosure have been described using the general terms mentioned above, but next we will refer to the attached figures, which are not necessarily drawn to the same scale. [Brief explanation of the drawing]

[0026] [Figure 1] This is a block diagram of an ethylene oligomerization system according to an exemplary implementation of the present disclosure. [Figure 2] This is a block diagram of an example of a 1-hexene purification process according to an exemplary implementation of the present disclosure. [Figure 3] The graph shows the conversion rates of 1-hexene and 2E1B over time during the experiment in Example 1. [Figure 4] The graph shows the conversion rates of 1-hexene and 2E1B over time during the experiment in Example 2. [Figure 5]The graph shows the conversion rates of 1-hexene and 2E1B over time during the experiment in Example 3. [Figure 6] The FTIR spectrum of unmodified gamma alumina is shown in graph form. [Modes for carrying out the invention]

[0027] Next, some examples of implementations of this disclosure will be described more fully below, with reference to the accompanying drawings, which show some, though not all, examples of implementations of this disclosure. In fact, various examples of implementations of this disclosure may be embodied in many different forms and should not be construed as being limited to the examples described herein; rather, these exemplary examples are provided so as to make this disclosure thoroughly complete and so as to convey the scope of this disclosure to those skilled in the art. Similar reference numerals refer to similar elements throughout.

[0028] Unless otherwise specified or evident from the context, the first, second, or similar references should not be interpreted as suggesting a particular order. A form described as being above another form (unless otherwise specified or evident from the context) may instead be below it, and vice versa; similarly, a form described as being to the left of another form may instead be to its right, and vice versa. Quantitative measures, values, geometric relationships, or similar may also be referred to herein, but unless otherwise specified, one or more of these may be absolute or approximate in order to describe any acceptable variation that may occur, such as that resulting from engineering tolerances or similar.

[0029] All ranges disclosed herein also include endpoints, which are independently combinable (for example, the range “up to 25% by weight, or more specifically 5% to 20% by weight” includes the endpoints of the range “5% to 25% by weight” and all intermediate values, etc.). “Combination” includes blends, mixtures, alloys, reaction products, and the like.

[0030] The terms “about” or “approximately” are defined as being close to what is understood by those skilled in the art. In one non-limiting embodiment, the terms are defined as being within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0031] As used herein, unless otherwise specified or it is clear from the context, the "or" in a pair of operands is an "inclusive disjunction," meaning true only if one or more of the operands are true, in contrast to the "exclusive OR," which is false when all of the 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 it is clear from the context that they refer to the singular form.

[0032] This disclosure provides a modified alumina catalyst having a Brønsted acid moiety that selectively isomerizes 2-ethyl-1-butene to cis- or trans-3-methyl-2-pentene in the presence of 1-hexene, in order to increase the purity level of 1-hexene produced by ethylene oligomerization. While not bound by operating theory, the intensity and density of the Brønsted acid moiety in the catalyst are considered to play an important role in selective isomerization. In certain embodiments, the modified alumina catalyst is characterized by having a Brønsted acid moiety of 0.01 to about 0.5 mmol / g of catalyst, as measured by FTIR spectroscopy using pyridine as a probe molecule.

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

[0034] Ethylene oligomerization process and system Linear alpha-olefins (LAOs) are olefins having the chemical formula C x H 2x and are distinguished from other monoolefins having similar molecular formulas by the linearity of the hydrocarbon chain and the position of the double bond at the first or alpha position. Linear alpha-olefins include 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and higher blends of olefins from C 20 to C 24 , C 24 to C 30 and C 20 to C 30 and include an industrially important class of alpha-olefins. Linear alpha-olefins are useful intermediates for manufacturing 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 the catalytic oligomerization of ethylene in the presence of a Ziegler-Natta type catalyst or a non-Ziegler-Natta type catalyst.

[0036] Oligomerization can be caused at a temperature of 10 to 200 °C, such as 20 to 100 °C, such as 5o 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, and the average residence time can be 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 rate with high selectivity.

[0037] The process can be carried out in a solution using an inert solvent that is advantageously non-reactive to the catalyst composition. Examples of desired organic solvents include, but are not limited to, unsubstituted or halogen-substituted aromatic hydrocarbons, e.g., toluene, benzene, xylene, monochlorobenzene, dichlorobenzene, chlorotoluene; aliphatic paraffinic hydrocarbons, e.g., pentane, hexane, heptane, octane, nonane, decane; alicyclic hydrocarbon compounds, e.g., cyclohexane, decahydronaphthalene; and halogenated alkanes, e.g., 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. Ethylene oligomerization is an exothermic reaction that can be cooled by the excess flow of ethylene. The gas escaping from the top of the reactor can be cooled using a series of external coolers and condensers. The gas phase after further cooling can be recirculated.

[0039] The bottom flow away from the bottom of the oligomerization reactor may contain the activated catalyst and unreacted ethylene. The reaction can be terminated to avoid undesirable side reactions by removing the catalyst component from the organic phase through extraction with the caustic aqueous phase. Contact with the caustic aqueous phase may result in the formation of unreacted inorganic substances corresponding to the catalyst component.

[0040] The organic phase, after passing through a catalytic removal system, can pass through a molecular sieve absorption bed and then be fed to a distillation column to recover dissolved ethylene. The recovered ethylene can be recycled through an ethylene recirculation loop, along with the product, which is fed to an intermediate tank, and then to a separation section. In certain embodiments, the linear alpha-olefin produced from the reactor can be directed to the separation column.

[0041] As shown in Figure 1, the system 10 may include a reactor 12, a toluene (or other solvent) supply 14, and a separation column 16. In a typical production mode, reactants 18 such as ethylene, a solvent, and a catalyst can be supplied into the reactor 12 to produce linear alpha-olefins and various impurities such as branched olefins and polymer materials. After the reaction, the discharge stream 20 can be directed into the separation column 16, which contains unreacted reactants, the generated linear alpha-olefins, e.g., C4-C4 20+ The olefin, solvent, catalyst, and various impurities may be included. Separation column 16 can be configured to separate linear alpha-olefins from the solvent, catalyst, various impurities, and any unreacted ethylene. Separation column 16 can separate each linear alpha-olefin, yielding, for example, a C4 stream, a C6 stream, a C8 stream, etc. Separation column 16 can separate the linear alpha-olefins into certain fractions, for example, C4-C 10 Distillate, C 11 ~C 17 Distillate, C 18 ~C 20 Distillate, C 20+ It can also be separated into fractions, or any other desired fractions.

[0042] Linear alpha-olefin products can be isolated using a procedure that includes aqueous caustic catalyst quenching, followed by washing with water and recovery of the final product by distillation. For example, a liquid product containing dissolved ethylene in a solvent (e.g., toluene) can be fed to separation column 16 as described above. In the first column, unused ethylene can be separated from the linear alpha-olefin products and solvent. The ethylene can be recycled back to the original reactor. The heavy fraction can be passed through a subsequent separation section, where it can be separated into various linear alpha-olefin fractions (e.g., C8, C8). 10 ,>C 12 It can be divided into ). The solvent can also be recovered and recycled back into 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 rate, reduced internal condenser performance, or increased differential pressure at various points within the reactor. Such fouling can be treated by flushing the reactor with toluene or another solvent to remove polymer material byproducts. The flushed toluene, containing the polymer material, can be directed into a separation column containing linear alpha-olefin reaction products. Since the polymer material is soluble in at least one of the linear alpha-olefins, the flushed toluene can exit through a separation column that is essentially free of polymer material and be recycled back to the original toluene source for subsequent reactor flushing.

[0044] 1-Hexene purification process If the desired alpha-olefin product in the ethylene oligomerization product stream is 1-hexene with a boiling point of 63.48°C, one example of a problematic impurity is 2-ethyl-1-butene with a boiling point of 64.67°C. For example, refer to the composition of a typical 1-hexene product stream described in Table 1 below.

[0045] [Table 1]

[0046] However, 2-ethyl-1-butene can be converted to higher boiling point 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 this disclosure, in certain embodiments, the separation column 16 in Figure 1 includes at least one isomerization reactor and at least one distillation column. An example of a purification system is shown in Figure 2. As illustrated, the system 100 may include a reactor 110 and a separation unit 112. A first stream 101 containing 1-hexene and 2-ethyl-1-butene can be supplied to the reactor 110. In the reactor 110, the first stream 101 can come into contact with an isomerization catalyst to form a second stream 102 containing 1-hexene and 3-methyl-2-pentene. The second stream 102 is typically supplied to the separation unit 112. In the separation unit 112, the second stream can 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 be modified in composition, but is typically at least 96% by weight or at least 98% by weight of 1-hexene (e.g., about 96% to about 98.5% by weight or about 98% to about 98.5%) and at least 0.5% by weight or at least 0.8% by weight of 2-ethyl-1-butene (e.g., about 0.5% to about 1.5% by weight or about 0.8% to about 1.2%).

[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 so that a first flow 101 can pass inside and / or over the stationary bed. In reactor 110, the flow 101 can come into contact with the isomerization catalyst to selectively isomerize 2-ethyl-1-butene in the first flow to 3-methyl-2-pentene.

[0051] The first flow 101 is, for example, i) a temperature between 40°C and 100°C, or between 40°C and 60°C, or between at least one, equal to one, 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 between 0.1 barg and 10 barg, or between at least one, equal to one, 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) 0.5 h -1 ~10h -1 , or 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10h -1 The isomerization catalyst can be brought into contact with at least one of these, an equal or equal to one of them, or between any two of them, or any combination thereof.

[0052] The conversion of 2-ethyl-1-butene for the isomerization reaction may be 50% to 100% by weight, for example, 70% to 100%, or 80% to 99.9%, or at least one, equal to any one, 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 between 50% and 100% by weight, or between at least one, equal to one, or between any two of 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 99, and 100% by weight. The conversion rate of 1-hexene during the isomerization reaction can be between 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 between 0.5% and 10%, or between any one of 0.5%, 1%, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and less than 10% by weight, or between any two of these.

[0053] The distillation column (e.g., separation unit 112) may be of various types, including columns having bubble cap trays, valve trays, or sieve trays. The use of isomerization catalysts as intended in this disclosure can reduce the number of steps that may ordinarily be required to achieve very high purity with respect to certain linear alphaolefins such as 1-hexene. For example, in certain embodiments, the number of distillation steps required to achieve a high degree of linear alphaolefin purity (e.g., about 99.5% by weight or higher) is about 150 steps or less, or about 120 steps or less (e.g., about 80 to about 150 steps).

[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. The operating conditions of the distillation column for separating the second stream 102 may include i) a temperature of 50°C to 100°C, or 55°C to 75°C, or at least one, 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, 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 those of 1-hexene, and therefore 3-methyl-2-pentene can be separated from 1-hexane by distillation of the second stream. In certain embodiments, a third stream 103 can be formed as the top distillate of the distillation column, and a fourth stream 104 can be formed as the bottom distillate of the distillation column.

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

[0056] Isomerization catalyst The isomerization catalyst can selectively isomerize 2-ethyl-1-butene in the presence of 1-hexene (and hexane, and other isomers of 1-hexene, if present) to form 3-methyl-2-pentene. In some embodiments, the catalyst material is 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," typically have a surface area of ​​60 m². 2 Exceeding / g, often around 200m 2 It exhibits a BET surface area of ​​up to or greater than / g. Such activated alumina is usually a mixture of the gamma and delta phases of alumina, but may contain significant amounts of the eta, kappa, and theta alumina phases. "BET surface area" has its usual meaning, referring to the Brunauer, Emmett, Teller method for determining surface area by N2 adsorption.

[0058] In a particular embodiment, the alumina material is 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 ii) BET surface area of ​​at least one, equal to one, or between any two of the following values ​​per g; ii) average particle size of 1 mm to 8 mm, or at least one, equal to one, or between any two of the following values: 1 mm to 8 mm; and / or iii) average crushing strength of 0.5 to 40 kg, or at least one, equal to one, or between any two of the following values: 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 chemically modified alumina materials to increase the presence of acidic functional groups. As used herein, “modified alumina” refers to alumina materials that have been chemically modified to enhance the acidic functionality of alumina. A non-limiting example of commercially available modified alumina is SELEXSORB® CD, available from BASF. Furthermore, there are known processes for preparing γ-Al2O3 rich in Brønsted acid moieties and reduced Lewis acid moieties using a sol-gel method with NH4BF4 as a modifier. See J.Phys.Chem.C2014, 118, 12, 6226-6234.

[0060] The alumina materials used in this disclosure are characterized by the presence of sufficient Brønsted acid moieties for the adsorption and isomerization of 2-ethyl-1-butene. For example, in certain embodiments, the alumina material has at least 0.01 mmol / g of Brønsted acid moieties as catalyst (e.g., at least 0.02 or at least 0.03 or at least 0.04 mmol / g), but typically has 0.5 mmol / g of Brønsted acid moieties as catalyst (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 Brønsted acid moieties, the catalyst is more likely to undergo non-selective isomerization, which may result in undesirable 1-hexene conversion. The concentration of Brønsted acid moieties can be measured by FTIR spectroscopy using pyridine as a probe molecule, as described experimentally. The Brønsted acid moiety of the modified alumina catalyst is weak in strength; that is, the pyridine probe molecules held by the Brønsted moiety may be desorbed under vacuum at approximately 150°C or above 150°C.

[0061] As described above, in certain embodiments, the isomerization catalyst can be characterized based on the extent to which an undesirable first isomer is converted to a second isomer. For example, in certain embodiments, the isomerization catalyst converts 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 a 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 about 0.5 to 10.0 hours. -1 The conversion can be performed at a liquid-space velocity. In some embodiments, about 3% or less by weight of 1-hexene (e.g., about 2% or less by weight, or about 1% or less by weight) is converted to different isomers under the same reaction conditions as described above.

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

[0063] Catalyst regeneration Surprisingly, we have found that the periodic regeneration of the modified alumina catalyst described herein can, in certain embodiments, result in robust catalytic performance that is sustainable for thousands of hours. Typically, the regeneration process involves ceasing 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 no more than about 200 hours of flow time. In certain embodiments, the reactor is exposed to the non-oxidizing environment for a period of about 15 hours or longer, and this non-oxidizing environment has a temperature of about 250°C or higher for at least part of that period. As described in the experiments below, such a regeneration process can be repeated to return the catalyst to the same performance level as a fresh catalyst.

[0064] The time interval between regeneration steps can be modified and depends in part on the moisture level in the feed stream. Higher moisture levels in the feed material often require shorter intervals between regeneration processes. For example, low moisture feed material with less than about 10 ppm of water can allow for longer intervals between regeneration steps, such as longer than about 120 hours, or longer than about 140 hours, or longer than about 160 hours, or longer than about 180 hours (e.g., about 150 to about 300 hours, or even longer). Conversely, higher moisture levels in the feed material (e.g., about 30 ppm or higher, e.g., about 30 to about 80 ppm) may result in shorter intervals, such as less than about 150 hours, or less than about 130 hours, or 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 nitrogen or a noble gas environment. A non-oxidizing environment is substantially or completely oxygen-free.

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

[0067] In certain embodiments, the lower temperature step may include passing an inert gas through the reactor at an inert gas temperature of about 150°C or less, for example, about 40°C to about 150°C. The lower temperature step itself may include a number of steps at various temperatures, for example, two or three temperature levels within the above temperature range. The total regeneration time in the lower temperature step can vary, but is typically about 4 hours or longer. In certain embodiments, the total regeneration time in the lower temperature step is about 2 to about 6 hours, or about 4 to about 6 hours. Higher temperatures usually allow for shorter periods with respect to this regeneration step. Therefore, those skilled in the art can choose to use lower temperatures in combination with longer periods, or choose higher temperatures and shorter periods within the above range. The inert gas flow rate during this step is typically about 120 to about 300 cm³. 3 / minute, for example, approximately 150-250cm 3 It is per minute.

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

[0069] In certain embodiments, the higher temperature step may include passing an inert gas through the reactor at an inert gas temperature of about 300°C or less, for example, an inert gas temperature of about 250°C to about 300°C. The higher temperature step itself may include a number of steps at various temperatures, for example, two or three temperature levels within the above temperature range. The total regeneration time in the higher temperature step may vary, but is typically about 14 hours or less. In certain embodiments, the total regeneration time in the lower temperature step is about 8 to about 14 hours, or about 10 to about 12 hours. Higher temperatures usually allow for shorter periods with respect to this regeneration step. Therefore, those skilled in the art can choose to use lower temperatures in combination with longer periods, or choose higher temperatures and shorter periods within the above range. The inert gas flow rate in this step is typically about 120 to about 300 cm³. 3 / minute, for example, approximately 150-250cm 3 It is per minute.

[0070] The non-oxidizing environment may become insufficient to fully regenerate the catalyst after a certain period of time during flow, due to the accumulation of carbon / coke 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, or at least 10 hours or longer, or at least 15 hours or longer, or at least 20 hours or longer). The regeneration time for removing carbonaceous chemical species depends on the temperature and concentration of the oxygen. Regeneration in an oxidizing environment may be applied when regeneration in a non-oxidizing environment does not improve the catalyst performance to the same level as that of a fresh catalyst. That is, in plant operation, such oxidative regeneration may be applied when the catalyst performance after non-oxidative regeneration quickly drops to a predetermined threshold level, as determined by the selectivity of the conversion rate or the cycle length.

[0071] It is advantageous to avoid exposing catalyst materials to sudden temperature changes during the regeneration process, which can lead to degradation of the catalyst structure. Therefore, when it is desirable to change the regeneration temperature, such changes are typically achieved using relatively small temperature change rates, for example, by raising or lowering the temperature at a rate of about 1 to 5°C / minute. [Examples]

[0072] experiment The following examples utilize Selexsorb® CD catalyst, commercially available from BASF. 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 pulverized into a fine powder and pressurized (under a pressure of 10 tons) to a diameter of 0.65 cm (surface area 1.33 cm²). 2 (having) and a weight of 0.02 g (i.e., 0.015 g / cm³) 2 The sample wafers were made into thin, self-supporting wafers. The sample wafers were heated to a maximum of 280°C for 4 to 24 hours under vacuum or in a stream of N2 (depending on whether the catalyst was fresh or used). The catalyst wafers were cooled and exposed to pyridine vapor at 100°C for 30 minutes, then desorbed under vacuum at 100°C. The infrared spectra of the pre-treated and pyridine-adsorbed samples were taken at room temperature using a Perkin-Elmer Spectrum One FTIR spectrometer at 4 cm². -2 The resolution was recorded as the average of 16 scans.

[0075] To determine the acidic site, we apply the Beer-Lambert-Bouguer principle. A = ε × Cs Apply in the form of, In the formula, Cs is the concentration of the Brønsted acid moiety in units of μmol / g, A is the integrated absorbance of the corresponding infrared band in units of cm / g, normalized with respect to the catalyst wafer density, and ε is the integrated molar absorption coefficient (see reference Gabrienko, AA, et al., Journal of Physical Chemistry, 122, p25386, 2018). The ε values ​​of 1.67 cm / μmol and 2.22 cm / μmol for pyridine adsorbed to the Brønsted acid moiety and Lewis acid moiety were taken from reference Emeis, CA, Journal of Catalysis, 141, p347, 1993.

[0076] [Example 1] Selexsorb® CD catalyst (size 1.4-1.7mm, perfect sphere, 17.56gm, 25cm) 3 The catalyst was placed in a 1-inch OD stainless steel tubular reactor, and glass inserts were added to both ends of the catalyst bed. The catalyst was then supplied with a flow of N2 (170 cm³). 3 The catalyst bed was dried at 45°C for 2 hours under a flow rate of 5°C / min, then heated to 150°C for 2 hours, then heated to 280°C for 5°C / min, and held for 12 hours. The catalyst bed temperature was cooled to 45°C, and the N2 flow was stopped to allow for the introduction of the feed material into the reactor.

[0077] The 1-hexene feed material was dried using molecular sieves 4A. The catalyst test was initiated by flowing the 1-hexene feed material at approximately 0.4 mL / min (the feed rate changed at the start, and the rate 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 material and product flow (at a flow time of 56.3 hours). The conversion rates of 2E1B and 1-H were found to be 98.73% and 0.09%, respectively. Most of the 2E1B was converted to cis- and trans-3-methyl-2-pentene.

[0079] The 2E1B conversion rate decreased with flow time. The catalyst was initially prepared by flowing N2 at 45°C for 2 hours (170 cm³). 3 The catalyst bed was purged (at 5°C / min), then heated to 150°C and held for 2 hours, then heated to 280°C and held for 12 hours, and subsequently cooled to 45°C to reintroduce the feed material into the reactor for regeneration. The total regeneration time was 16 hours, at 170 cm³. 3 Under a flow of N2 per minute, there were three temperature steps.

[0080] The regeneration process was repeated periodically as the catalyst performance deteriorated. In this example, most of the regeneration steps were performed after 300 hours of flow time had elapsed. As shown graphically in Figure 3, the catalyst performance deteriorated over time, and the periodic regeneration process was unable to restore the catalyst to its initial performance level.

[0081] [Table 3]

[0082] [Example 2] The experiment in Example 1 was repeated with a slightly different catalyst load (Selexsorb(registered trademark) CD; 24.34 g; 36 cm³). 3 The process was repeated using the same catalytic drying process as in Example 1.

[0083] Compared to catalyst regeneration in Example 1, a longer duration of N2 flow was used in Example 2, along with the addition of a step. The catalyst was first regenerated by flowing N2 (170 cm) at 45°C for 2 hours. 3 The catalyst bed was purged (at 5°C / min), then heated to 60°C and held for 12 hours, then heated to 150°C and held for 4 hours, then heated to 280°C and held for 12 hours, and then cooled to 45°C and reintroduced the feed material into the reactor for regeneration. The total regeneration time was approximately 30 hours, at 170 cm². 3 Under a flow of N2 per minute, there were four temperature steps.

[0084] Table 4 below shows the composition of the feed material and product flow (at a flow time of 126.6 hours). The conversion rates of 2E1B and 1-H were found to be 97.47% and 0.04%, respectively. Most of the 2E1B was converted to cis- and trans-3-methyl-2-pentene.

[0085] In Example 2, catalyst lifetime increased with increasing N2 flow duration, along with shorter intervals between step additions and regeneration (compared to Example 1). Catalyst performance was maintained over time, as shown graphically in Figure 4. Most regeneration steps were performed after less than 200 hours of flow time.

[0086] [Table 4]

[0087] [Example 3] Selexsorb® CD catalyst (size 2.8-3.2mm, perfect sphere, 6.1g, 9cm) 3 The catalyst was placed in 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 fed into a stream of N2 (200 cm³). 3 The catalyst bed was dried at 45°C for 2 hours under a flow rate of 2°C / min, then heated to 150°C for 2 hours, then heated to 280°C for 12 hours. The catalyst bed temperature was cooled to 45°C and the N2 flow was stopped to feed the material into the reactor.

[0088] The 1-hexene feed material was dried by purging with nitrogen gas for 0.5 hours. The catalyst test was initiated by flowing the 1-hexene feed material 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 material and product flow (after 192 hours of flow). The conversion rates of 2E1B and 1-H were found to be 97.72% and 0.01%, respectively. Most of the 2E1B was converted to cis- and trans-3-methyl-2-pentene.

[0089] The conversion rate of 2-ethyl-1-butene decreased with flow time. The catalyst was initially prepared by flowing N2 at 45°C for 2 hours (200 cm³). 3 The catalyst bed was purged (at 2°C / min), then heated to 150°C and held for 2 hours, then heated to 280°C and held for 12 hours, and subsequently cooled to 45°C and the feed material was reintroduced to the reactor for periodic regeneration. The total N2 regeneration time was approximately 16 hours, at 200 cm³. 3 Under a flow of N2 per minute, there were three temperature steps. The catalyst was also subjected to an air regeneration step once during the experiment at 1924 hours. Air regeneration consisted of (a) stopping the 1-hexene feed flow and purging hydrocarbons through N2 gas for about 1 hour, and (b) supplying air at 200 cm³. 3 The procedure consisted of (c) running the air at a rate of 5°C / min to raise the catalyst bed temperature to 110°C and holding it for 2 hours, and (d) raising the temperature to 350°C (1°C / min) and holding it for 5 hours. The catalyst bed temperature was cooled to room temperature, N2 was purged, and then the catalyst test was performed. The air regeneration step was able to restore the catalyst to the same performance level as a fresh catalyst after repeated N2 regeneration had caused the catalyst performance to begin to deteriorate.

[0090] In Example 3, catalyst lifetime increased with frequent catalyst N2 regeneration (compared to Example 1). As shown graphically in Figure 5, catalyst performance was maintained over time, and no noticeable performance degradation occurred for a period longer than 2500 hours (under normal regeneration). Most regeneration steps were performed after a flow time of 200 hours or less. Table 6 below shows the frequency and type of regeneration used in each regeneration step.

[0091] [Table 5]

[0092] [Table 6]

[0093] [Example 4] In another experiment, fresh samples of Selexsorb® CD were analyzed using FTIR spectroscopy, employing pyridine as a probe molecule for measuring Brønsted and Lewis acid moieties. Used catalysts from Example 2 were subjected to the same acid moiety analysis as the comparative examples after catalyst testing for approximately 850 hours with frequent N2 regeneration at 280°C. The results are described in Table 7 below. Each sample was pre-treated as shown in Table 7 before analysis. As shown, longer N2 treatment of used catalysts can restore Brønsted acid moieties, which is consistent with the results described in Examples 1-3.

[0094] [Table 7]

[0095] [Comparative Example 1] The experiment in Example 1 was repeated using various alumina catalysts: Selexsorb® CDL, available from BASF, and Actisorb® 100-1, available from Clariant Ltd. Unlike Selexsorb® CD, none of these adsorbents are considered to have Brønsted acid moieties within the scope described herein.

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

[0097] [Table 8]

[0098] [Comparative Example 2] Unmodified gamma alumina was analyzed using FTIR spectroscopy with pyridine as the probe molecule to measure the Brønsted and Lewis acid moieties, as described above. The FTIR spectrum is shown in Figure 6, at 1450 cm⁻¹. -1 A peak is shown at 1545 cm (Lewis acid site), but at 1545 cm. -1 No peaks (characteristic peaks related to the Brønsted acid moiety) were found in the vicinity. This is consistent with the idea that the presence of the Brønsted acid moiety is important for strong 2E1B conversion performance.

[0099] In general, the present invention may consist of, or be essentially composed of, any suitable components disclosed herein, alternately. The present invention may be added to or instead of any components, materials, ingredients, adjuvants, or chemical species used in prior art compositions, or any that are not ordinarily necessary to achieve the function and / or purpose of the present invention.

[0100] Many modifications and other practices of this disclosure will be conceivable to those skilled in the art to which this disclosure relates, who are of interest in the teachings presented in the foregoing description and the associated figures. Therefore, it should be understood that this disclosure is not limited to the specific practices disclosed herein, and modifications and other practices are intended to be included within the scope of the appended claims. Certain terms are used herein, but they are used only in a general and descriptive sense and are not intended to be limiting.

Claims

1. A catalytic process for the selective isomerization of 2-ethyl-1-butene in a stream of linear alpha-olefin products, A feeding step comprising supplying a stream of linear alphaolefin product containing at least one linear alphaolefin and 2-ethyl-1-butene to a reactor containing a modified alumina catalyst, thereby isomerizing at least a portion of 2-ethyl-1-butene to cis- or trans-3-methyl-2-pentene, wherein the period during which the supply takes place is the flow time; A step of drawing out the effluent from the reactor containing less 2-ethyl-1-butene than the linear alpha-olefin product flow, A regeneration step comprising stopping the supply process and introducing a non-oxidizing environment into the reactor at flow time intervals of 200 hours or less to periodically regenerate the modified alumina catalyst, wherein the reactor is exposed to the non-oxidizing environment for a period of 15 hours or longer, and the non-oxidizing environment has a temperature of 250°C or higher for at least a portion of that period, and A catalytic process, including

2. The catalytic process according to claim 1, wherein the at least one linear alphaolefin is 1-hexene.

3. The catalytic process according to claim 1, wherein the non-oxidizing environment includes a vacuum environment or an inert gas environment.

4. The catalytic process according to claim 3, wherein the inert gas environment is nitrogen or a noble gas environment.

5. The catalyst process according to claim 1, wherein the regeneration step comprises passing the inert gas through the reactor in two consecutive steps, i) passing the inert gas through the reactor for a period of two hours or longer at an inert gas temperature of 200°C or less, and ii) passing the inert gas through the reactor for a period of eight hours or longer at an inert gas temperature of 250°C or higher.

6. The first lower temperature step is, Passing the inert gas through the reactor at an inert gas temperature of 150°C or less, The inert gas is passed through the reactor at an inert gas temperature of 40°C to 150°C. Passing the inert gas through the reactor at multiple inert gas temperatures ranging from 40°C to 150°C, wherein the temperature of the inert gas is raised to each of the multiple inert gas temperatures at a rate of 1 to 5°C / min, Passing the inert gas through the reactor for a period of 4 hours or longer, and Passing the inert gas through the reactor for a period of 2 to 6 hours. The catalytic process according to claim 5, comprising one or more of the above.

7. The second higher temperature step is, Passing the inert gas through the reactor at an inert gas temperature of 300°C or less, The inert gas is passed through the reactor at an inert gas temperature of 250°C to 300°C. Passing the inert gas through the reactor for a period of 14 hours or less, and Passing the inert gas through the reactor for a period of 8 to 12 hours. The catalytic process according to claim 5, comprising one or more of the above.

8. The catalytic process according to claim 5, wherein the transition from the first lower temperature stage to the second higher temperature stage is induced at a rate of 1 to 5°C / min.

9. The inert gas flow rate is 120-300 cm³. ３ The catalytic process according to claim 5, wherein the rate is per minute.

10. The catalyst process according to claim 1, further comprising periodically regenerating the modified alumina catalyst by stopping the supply process and introducing an oxidizing gas into the reactor.

11. The catalytic process according to claim 10, wherein the oxidizing gas contains oxygen at a gas temperature of 300°C to 450°C, and the oxidizing gas is optionally introduced over a period of 1 to 24 hours.

12. The modified alumina catalyst is subjected to a process in which 80% by weight or more of 2-ethyl-1-butene is converted to cis- or trans-3-methyl-2-pentene at a pressure of 0.1 to 10 barg, a temperature of 40 to 100°C, and 0.5 to 10 hours. －１ The catalytic process according to claim 1, wherein conversion is possible at a liquid-space velocity, and 3% by weight or less of 1-hexene is converted to different isomers under the same reaction conditions.

13. The catalytic process according to claim 1, further comprising supplying the effluent from the reactor to a distillation column to generate a top flow containing the linear alphaolefin and a bottom flow containing cis- or trans-3-methyl-2-pentene.

14. The catalytic process according to claim 13, wherein the top flow of the column contains 99.5% by weight or more of 1-hexene and 0.15% by weight or less of 2-ethyl-1-butene or its isomer.

15. The catalytic process according to any one of claims 1 to 14, wherein the modified alumina catalyst has a Brønsted acid moiety of 0.01 to 0.5 mmol / g of catalyst as measured by FTIR spectroscopy using pyridine as a probe molecule.

16. The catalytic process according to claim 15, wherein the modified alumina catalyst has a Brønsted acid moiety of 0.04 to 0.2 mmol / g of catalyst, as measured by FTIR spectroscopy using pyridine as a probe molecule.

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