Separation method for olefin oligomerization reaction product, and method and device for preparing ethylene oligomer by using separation method
By using a partition tower for distillation and separation after ethylene oligomerization, the problems of high energy consumption and complex equipment in the existing process are solved, and a more economical and stable separation process is achieved.
Patent Information
- Application Number
- CN202411408707.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-10-17
- Filing Date
- 2024-10-10
- Publication Date
- 2025-04-18
AI Technical Summary
The existing separation process after ethylene oligomerization has high energy consumption and complex equipment, resulting in increased costs and unstable product quality.
The mixture containing solvent and C8 or above linear alpha olefins was separated into solvent, C8 linear alpha olefins and C10 or above linear alpha olefins by one treatment.
Significantly reduces energy usage, reduces initial equipment investment and maintenance costs, and improves process stability and efficiency.
Smart Images
Figure CN119841701A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for separating olefin oligomerization products and a method and apparatus for preparing ethylene oligomers using the separation method, and more specifically, to a method for separating a mixture containing a solvent and C8 or higher linear alpha olefins produced after ethylene oligomerization into a solvent, C8 linear alpha olefins and C10 or higher linear alpha olefins even through a one-time treatment, and a method and apparatus for preparing ethylene oligomers using the separation method. Background Art
[0002] Linear alpha olefins (LAO), also known as linear alpha alkenes, linear terminal olefins, linear terminal alkenes or normal alpha olefins, are mainly used as raw materials for various chemical processes such as comonomers in polymerization processes, precursors in oxidation production processes of aldehydes and / or carboxylic acids, starting materials in higher olefin production processes, and they are also used directly as raw material components for surfactants, lubricants, detergents, etc. Specifically, among linear alpha olefins, 1-hexene and 1-octene are substances used in large quantities as comonomers in the polymerization production of polyolefins such as polyethylene, and their demand is steadily increasing with the increase in the production of polyolefins using homogeneous metallocene catalysts.
[0003] Linear alpha olefins are mainly synthesized by ethylene oligomerization process using Ziegler-type catalysts. The product of this ethylene oligomerization process is usually a (full range) mixture of linear alpha olefins above C4 with an even number of carbon atoms (such as 1-butene, 1-hexene, 1-octene, 1-decene, etc.).
[0004] The product stream of this ethylene oligomerization process includes a variety of linear alpha olefins, unreacted ethylene and a solvent inert to the oligomerization reaction. After subsequent multiple distillation processes, they are separated into separate linear alpha olefins, unreacted ethylene and solvent, and the separated ethylene and solvent are recovered and reused.
[0005] In addition, when using C7 saturated hydrocarbons such as methylcyclohexane, heptane, etc. as an inert solvent to separate C8 linear α-olefins, i.e., 1-octene, which is a key material, from the reaction products of the ethylene oligomerization process, the amount of solvent to be separated is very large, and methylcyclohexane, heptane, etc. are lighter than 1-octene. Therefore, in the existing process, the solvent is heated in a solvent distillation tower and discharged from the overhead of the tower, and C8 and above linear α-olefins are discharged from the bottom of the tower. These C8 and above linear α-olefins are then fed into a subsequent distillation tower and heated to recover 1-octene from the overhead, and C10 and above linear α-olefins are discharged from the bottom of the tower, thereby separating 1-octene.
[0006] However, this existing separation method is disadvantageous in terms of process economy because it uses too much energy for separation, which increases the cost for operation, and requires multiple distillation columns, which increases the cost for initial equipment investment and equipment maintenance. In addition, the equipment becomes complicated, which makes the stability and efficiency of the process worse, resulting in unstable quality and output of the final product. Summary of the invention
[0007] Technical issues to be resolved
[0008] The object of the present invention is to provide a method for separating a mixture containing a solvent and C8 or higher linear alpha olefins produced after ethylene oligomerization into a solvent, C8 linear alpha olefins and C10 or higher linear alpha olefins in a more economical and simpler manner, as well as a method and an apparatus for preparing ethylene oligomers using the separation method.
[0009] Technical Solution
[0010] A first aspect of the present invention relates to a method for separating a mixture comprising a solvent and C8 or higher linear alpha olefins, the method comprising:
[0011] A mixture containing a solvent having a boiling point lower than that of C8 linear alpha olefins, C8 linear alpha olefins, and C10 or higher linear alpha olefins is distilled in a dividing wall column to discharge the solvent from the top of the dividing wall column, discharge the C8 linear alpha olefins from the first side of the dividing wall column, and discharge the C10 or higher linear alpha olefins from the bottom of the dividing wall column or a side lower than the first side of the dividing wall column.
[0012] In one embodiment, the solvent having a boiling point lower than that of C8 linear alpha olefins used may be an aliphatic hydrocarbon solvent having 5 to 20 carbon atoms, an aromatic hydrocarbon solvent having 6 to 20 carbon atoms, or a mixture thereof, more specifically, it may be selected from the group consisting of benzene, toluene, xylene, chlorobenzene, dichlorobenzene, pentane, hexane, heptane, methylcyclohexane, cyclohexane, and combinations thereof.
[0013] In one embodiment, the mixture may include 50 wt% to 95 wt% of a solvent having a boiling point lower than a C8 linear alpha olefin, 4 wt% to 40 wt% of a C8 linear alpha olefin, and 0.5 wt% to 10 wt% of a C10 or higher linear alpha olefin, based on a total 100 wt% of the mixture.
[0014] In one embodiment, the distillation in the dividing wall column may be performed at a temperature of 40° C. to 250° C. and a pressure of 0.1 bar to 15 bar.
[0015] In one embodiment, the C10 and above linear alpha olefins discharged from the dividing wall column are additionally distilled.
[0016] A second aspect of the present invention relates to a method for preparing ethylene oligomers, the method comprising the following steps:
[0017] (1) carrying out ethylene oligomerization in a solvent having a boiling point lower than that of C8 linear alpha olefins;
[0018] (2) separating a mixture comprising a solvent and C8 or higher linear alpha olefins from the reaction mixture obtained in step (1); and
[0019] (3) distilling the mixture containing the solvent and C8 or higher linear alpha olefins separated in step (2) in a dividing wall tower to discharge the solvent from the top of the dividing wall tower, discharge the C8 linear alpha olefins from the first side of the dividing wall tower, and discharge the C10 or higher linear alpha olefins from the bottom of the dividing wall tower or a side lower than the first side of the dividing wall tower.
[0020] In one embodiment, the solvent having a boiling point lower than that of C8 linear alpha olefins used may be an aliphatic hydrocarbon solvent having 5 to 20 carbon atoms, an aromatic hydrocarbon solvent having 6 to 20 carbon atoms, or a mixture thereof, more specifically, it may be selected from the group consisting of benzene, toluene, xylene, chlorobenzene, dichlorobenzene, pentane, hexane, heptane, methylcyclohexane, cyclohexane, and combinations thereof.
[0021] In one embodiment, additionally in step (2), unreacted ethylene is recovered and reused in the ethylene oligomerization reaction in step (1).
[0022] In one embodiment, in addition in step (2), C6 or lower linear alpha olefin is separated from the reaction mixture obtained in step (1).
[0023] In one embodiment, the C6 and below linear alpha olefins separated in step (2) are further distilled.
[0024] In one embodiment, the mixture distilled in the dividing wall column in step (3) may contain 50 wt % to 95 wt % of a solvent having a boiling point lower than C8 linear alpha olefin, 4 wt % to 40 wt % of C8 linear alpha olefin, and 0.5 wt % to 10 wt % of C10 or higher linear alpha olefin, based on the total 100 wt % of the mixture.
[0025] In one embodiment, the distillation in the dividing wall column in step (3) may be performed at a temperature of 40° C. to 250° C. and a pressure of 0.1 bar to 15 bar.
[0026] In one embodiment, the solvent discharged from the dividing wall column in the recovery step (3) is reused in the ethylene oligomerization reaction in the step (1).
[0027] In one embodiment, the C10 or higher linear alpha olefin discharged from the dividing wall column in step (3) is further distilled.
[0028] A third aspect of the present invention relates to a device for preparing ethylene oligomers, the device comprising:
[0029] (a) ethylene oligomerization reactor;
[0030] (b) a first distillation column in fluid communication with the bottom of the ethylene oligomerization reactor; and
[0031] (c) a dividing wall column in fluid communication with the bottom of the first distillation column,
[0032] The device operates in the following manner:
[0033] In the ethylene oligomerization reactor, the ethylene oligomerization reaction is carried out in a solvent having a boiling point lower than that of C8 linear alpha olefins.
[0034] The resulting mixture of the ethylene oligomerization reaction is discharged from the bottom of the ethylene oligomerization reactor and then fed to a first distillation column and distilled therein,
[0035] As a result of the distillation in the first distillation column, a mixture containing the solvent and C8 or higher linear α-olefins is discharged from the bottom of the first distillation column, and then fed to the dividing wall column and distilled therein, and
[0036] As a result of distillation in the dividing wall column, the solvent is discharged from the top of the dividing wall column, the C8 linear α olefin is discharged from the first side of the dividing wall column, and the C10 or higher linear α olefin is discharged from the bottom of the dividing wall column or the side lower than the first side of the dividing wall column.
[0037] In one embodiment, the apparatus for preparing ethylene oligomers further comprises an ethylene recovery line fluidly connecting the first distillation column and the ethylene oligomerization reactor.
[0038] In one embodiment, the apparatus for preparing ethylene oligomers further comprises an apparatus for distilling C6 or lower linear alpha olefins in fluid communication with the top of the first distillation column.
[0039] In one embodiment, the apparatus for preparing ethylene oligomers further comprises a solvent recovery line fluidly connecting the dividing wall column and the ethylene oligomerization reactor.
[0040] In one embodiment, the apparatus for preparing ethylene oligomers further comprises an apparatus for distilling C10 and above linear alpha olefins in fluid communication with the bottom of the dividing wall column.
[0041] Effects of the Invention
[0042] According to the present invention, in the ethylene oligomerization reaction, compared with the existing conventional separation process, when producing products with the same specifications as the existing process, the energy usage can be significantly reduced, and since the equipment becomes simple, the cost of initial equipment investment and equipment maintenance can be reduced, which has an economic advantage and also has the effect of improving process stability and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0043] Figure 1 Corresponding to the comparative example of the present invention, the existing conventional process for ethylene oligomerization and product separation is schematically shown.
[0044] Figure 2 Corresponding to the examples of the present invention, a process for ethylene oligomerization and product separation according to an embodiment of the present invention is schematically illustrated.
[0045] Figure 3 Schematic diagram for further distillation from Figure 2One embodiment of a process for producing C10+ linear alpha olefins discharged from the process is shown.
[0046] Figure 4 Schematic diagram for further distillation from Figure 2 Another embodiment of a process for producing C10+ linear alpha olefins discharged from the process is shown. DETAILED DESCRIPTION
[0047] The present invention will be described in more detail below.
[0048] As used herein, the term "linear alpha olefin" (LAO) refers to a linear olefin compound having a terminal unsaturated double bond.
[0049] As used herein, the term "ethylene oligomer" or "ethylene oligomer" refers to a linear alpha olefin (chemical formula C 2n H 4n , wherein n is a positive integer greater than 2), which may be, for example, 1-butene, 1-hexene, 1-octene or 1-decene, etc., but is not limited thereto.
[0050] As symbols used in this article, "Cx" represents a linear alpha olefin (or ethylene oligomer) having x carbon atoms, "Cx-" represents a linear alpha olefin having less than x carbon atoms, and "Cx+" represents a linear alpha olefin having more than x carbon atoms. For example, "C8" is a linear alpha olefin having 8 carbon atoms, namely 1-octene, "C8-" is a linear alpha olefin having less than 8 carbon atoms, namely including 1-butene, 1-hexene and 1-octene, and "C8+" is a linear alpha olefin having more than 8 carbon atoms, namely including 1-octene, 1-decene, 1-dodecene, etc.
[0051] In the present invention, a "dividing wall column" (DWC) includes one or more dividing walls in a distillation column, and the space in the distillation column is divided into two or more spaces by the dividing wall. If a mixture is distilled in a dividing wall column, three or more distillation product streams are discharged, wherein the lightest stream (lowest boiling point) is discharged from the top of the dividing wall column, the heaviest stream (highest boiling point) is discharged from the bottom of the dividing wall column, and the intermediate stream (s) is discharged through one or more sides (one or more sides) provided on the wall surface of the dividing wall column. If there is one dividing wall, it is called a single dividing wall column, in which case three distillation product streams (top / side / bottom) are discharged. If there are two or more dividing walls, it is called a multi-dividing wall column, in which case four or more distillation product streams are discharged. For example, in the case of a double dividing wall column having two dividing walls, four distillation product streams (top / first side / second side / bottom) are discharged. The present specification Figure 2 and Figure 4 Single dividing wall columns (500, 510, 520) are shown.
[0052] In one embodiment of the present invention, the solvent having a boiling point lower than that of C8 linear alpha olefins may be an aliphatic hydrocarbon solvent having 5 to 20 carbon atoms, an aromatic hydrocarbon solvent having 6 to 20 carbon atoms, or a mixture thereof, more specifically, it may be selected from the group consisting of benzene, toluene, xylene, chlorobenzene, dichlorobenzene, pentane, hexane, heptane, methylcyclohexane, cyclohexane, and a combination thereof, still more specifically, it may be selected from the group consisting of methylcyclohexane, cyclohexane, heptane, and a combination thereof, preferably, it may be methylcyclohexane.
[0053] In one embodiment of the present invention, the mixture distilled in the dividing wall column may contain 50 wt% to 95 wt% of a solvent having a boiling point lower than C8 linear alpha olefins, 4 wt% to 40 wt% of C8 linear alpha olefins, and 0.5 wt% to 10 wt% of C10 or higher linear alpha olefins, based on the total 100 wt% of the mixture.
[0054] If the content of the solvent is less than 50 wt % in the total 100 wt % of the mixture distilled in the dividing wall column, there may be a problem of clogging the line due to excessive oligomerization and polymers produced thereby, whereas if the content of the solvent is more than 95 wt %, there may be a problem of reduced productivity due to insufficient production of C8 and an increase in the ratio of C4 to C6.
[0055] More specifically, the content of the solvent in the total 100 wt % of the mixture distilled in the dividing wall tower may be 55 wt % or more, 60 wt % or more, 65 wt % or more, 70 wt % or more, 75 wt % or more, or 80 wt % or more, and may also be 94 wt % or less, 93 wt % or less, 92 wt % or less, 91 wt % or less, or 90 wt % or less, but is not limited thereto.
[0056] In addition, more specifically, the content of C8 linear α-olefins in the total 100 wt% of the mixture distilled in the dividing wall column may be 5 wt% or more, 6 wt% or more, 7 wt% or more, 8 wt% or more, or 9 wt% or more, and may also be 35 wt% or less, 30 wt% or less, 25 wt% or less, 20 wt% or less, or 15 wt% or less, but is not limited thereto.
[0057] In addition, more specifically, the content of C10 or higher linear α-olefins in the total 100 wt % of the mixture distilled in the dividing wall column may be 0.6 wt % or more, 0.7 wt % or more, 0.8 wt % or more, 0.9 wt % or more, or 1 wt % or more, and may also be 9 wt % or less, 8 wt % or less, 7 wt % or less, 6 wt % or less, or 5 wt % or less, but is not limited thereto.
[0058] In one embodiment of the present invention, the distillation in the dividing wall column may be performed at a temperature of 40° C. to 250° C. and a pressure of 0.1 bar to 15 bar.
[0059] If the temperature during distillation in the dividing wall column is lower than 40° C., there may be a problem that all components are not distilled but discharged through the bottom of the column and the top of the distillation column dries up, whereas if the temperature is higher than 250° C., there may be a problem that all components are distilled and discharged through the top of the column and thus the bottom of the distillation column dries up. In addition, if the pressure during distillation in the dividing wall column is lower than 0.1 bar, there may be a problem that the boiling point of the fluid is lowered, so that normal separation cannot be performed, the purity of the solvent discharged from the top of the column and recycled is reduced, so that the reactivity is reduced, and the purity of 1-octene is reduced, whereas if the pressure is higher than 15 bar, there may be a problem that the boiling point of the fluid is increased to more than 250° C., so that normal distillation cannot be performed, resulting in a reduction in the production amount of 1-octene, a loss of solvent due to the solvent being discharged from the side instead of the top of the column, and a reduction in the purity of 1-octene discharged from the side.
[0060] More specifically, the temperature conditions during distillation in the dividing wall tower may be 41° C. or higher, 42° C. or higher, 43° C. or higher, 44° C. or higher, 45° C. or higher, 46° C. or higher, 47° C. or higher, 48° C. or higher, 49° C. or higher, or 50° C. or higher, and may also be 250° C. or lower, 240° C. or lower, 230° C. or lower, 220° C. or lower, 210° C. or lower, 200° C. or lower, 190° C. or lower, or 180° C. or lower, but are not limited thereto.
[0061] In addition, more specifically, the pressure conditions during distillation in the dividing wall column can be above 0.15 bar, above 0.2 bar, above 0.25 bar or above 0.3 bar, and can also be below 15 bar, below 14 bar, below 12 bar, below 10 bar, below 8 bar, below 6 bar, below 5 bar, below 4 bar, below 3 bar, below 2 bar or below 1 bar, but are not limited thereto.
[0062] In one embodiment of the present invention, at the top of the dividing wall tower, the temperature condition may be above 40°C, above 45°C or above 50°C, and may also be below 80°C, below 70°C or below 60°C, but are not limited thereto; the pressure condition may be above 0.1 bar, above 0.15 bar or above 0.2 bar, and may also be below 1 bar, below 0.85 bar, below 0.5 bar or below 0.4 bar, but are not limited thereto.
[0063] In one embodiment of the present invention, on the side of the dividing wall tower, the temperature conditions may be above 60°C, above 70°C or above 80°C, and may also be below 130°C, below 120°C, below 110°C or below 100°C, but are not limited thereto; the pressure conditions may be above 0.3 bar, above 0.35 bar or above 0.4 bar, and may also be below 1.2 bar, below 1 bar, below 0.8 bar or below 0.6 bar, but are not limited thereto.
[0064] In one embodiment of the present invention, at the bottom of the dividing wall tower, the temperature condition may be above 130°C, above 140°C or above 150°C, and may also be below 250°C, below 240°C, below 230°C, below 220°C, below 200°C or below 180°C, but are not limited thereto; the pressure condition may be above 0.4 bar, above 0.45 bar or above 0.5 bar, and may also be below 15 bar, below 14 bar, below 12 bar, below 10 bar, below 8 bar, below 6 bar, below 5 bar, below 4 bar, below 3 bar, below 2 bar or below 1 bar, but are not limited thereto.
[0065] In one embodiment of the present invention, the C10 or higher linear alpha olefin discharged from the dividing wall column is additionally distilled.
[0066] In one embodiment, the C10 or higher linear alpha olefins may be further distilled by passing through one or more distillation towers in sequence. Figure 3 As shown, the C10+ linear alpha olefin stream (C10+) discharged from the dividing wall tower is distilled by passing through four distillation towers (610, 620, 630, 640) in sequence, thereby collecting C10, C12, C14 and C16 from the top of each distillation tower, respectively, and discharging the final residue C18+ from the bottom of the final distillation tower (640). Alternatively, as described in this specification Figure 4 As shown, C10+ discharged from the dividing wall tower is distilled by passing through two single dividing wall towers (510, 520) in sequence, so that C10 and C12 are collected from the top and side of the dividing wall tower (510), respectively, and C14 and C16 are collected from the top and side of the dividing wall tower (520), respectively, and the final residue C18+ is discharged from the bottom of the final dividing wall tower (520).
[0067] In the method for preparing ethylene oligomers as the second aspect of the present invention, in step (1), the ethylene oligomerization reaction is carried out in a solvent having a boiling point lower than that of C8 linear α-olefin.
[0068] The solvent having a boiling point lower than that of C8 linear α-olefin is the same as described above, and the ethylene oligomerization reaction can be carried out in the presence of a catalyst according to a known method.
[0069] For the above-mentioned catalyst, any known catalyst for ethylene oligomerization reaction can be used without particular limitation. More specifically, any known chromium catalyst can be used directly or appropriately modified. For example, the chromium compound of the following chemical formula 1 disclosed in Korean Patent Publication No. 10-2022-0087986 can be used as a catalyst, but is not limited thereto.
[0070] [Chemical formula 1]
[0071]
[0072] In the above chemical formula 1,
[0073] R is a C1-C60 alkyl group or a C6-C60 aryl group;
[0074] R 1 To R 4 Each is independently a C1-C60 alkyl group or a C6-C60 aryl group;
[0075] X 1 and X 2Each independently is a C1-C30 hydrocarbon group selected from one or more of halogen, C1-C30 alkyl, C1-C30 alkylcarboxylate, acetylacetonate, ether and amino;
[0076] A is boron or aluminum;
[0077] Y 1 To Y 4 are each independently a C6-C60 aryl group substituted by fluorine, a C6-C60 aryloxy group substituted by fluorine, or a C6-C60 alkoxy group substituted by fluorine; and
[0078] The alkyl or aryl group of the above R and the above R 1 To R 4 The alkyl or aryl group may also be substituted by one or more selected from the group consisting of a C1-C30 alkyl group, a C6-C30 aryl group, a C1-C30 alkoxy group, a mono-C1-C30 alkylamino group, a di-C1-C30 alkylamino group, a tri-C1-C30 alkylamino group, a mono-C6-C30 arylamino group, a di-C6-C30 arylamino group, a tri-C6-C30 arylamino group, a mono-C1-C30 alkylsilyl group, a di-C1-C30 alkylsilyl group, a tri-C1-C30 alkylsilyl group, a mono-C6-C30 arylsilyl group, a di-C6-C30 arylsilyl group and a tri-C6-C30 arylsilyl group.
[0079] In addition, there is no particular limitation on the method for oligomerizing ethylene. For example, as disclosed in Korean Laid-Open Patent No. 10-2022-0087986, the oligomerization of ethylene can be carried out at an ethylene pressure of 0 to 100 kgf / cm 2 and the reaction temperature is 0°C to 150°C. More specifically, the reaction can be carried out at an ethylene pressure of 20 kgf / cm 2 Up to 80kgf / cm 2 and the reaction temperature is 20°C to 120°C. More specifically, the reaction can be carried out at an ethylene pressure of 30 kgf / cm 2 Up to 60kgf / cm 2 The reaction is carried out at a temperature of 40°C to 100°C, but is not limited thereto.
[0080] Unless otherwise specified, all contents described in Korean Laid-Open Patent No. 10-2022-0087986, including the chromium compound of the above Chemical Formula 1 and ethylene oligomerization conditions, are utilized herein as a reference for the ethylene oligomerization reaction.
[0081] In one embodiment of the invention, after the ethylene oligomerization reaction in step (1), a deoxidant (killing agent) is immediately added to the resulting reaction mixture to prevent further reaction in the subsequent separation process. The deoxidant used can be selected from the group consisting of 1-butanol, 2-butanol, isobutyl alcohol, sec-butyl alcohol, the tert-butyl alcohol, 1-hexanol, 2-hexanol, 3-hexanol, 1-heptanol, 2-heptanol, 3-heptanol, 4-heptanol, 1-octanol, 2-octanol, 3-octanol, 4-octanol, 2-ethyl-1-hexanol, 2-methyl-3-heptanol, 1-decanol, 2-decanol, 3-decanol, 4-decanol, 5-decanol, 1-undecanol, 2-undecanol, 7-methyl-2-decanol, 1-dodecanol, 2-dodecanol, 2-ethyl-1-decanol and mixtures thereof One or more, but not limited thereto.
[0082] Preferably, in order to prevent the deoxidizer from being recovered together during solvent recovery, one or more selected from the group consisting of 1-octanol, 1-decanol, 1-dodecanol, 2-ethyl-1-hexanol, 2-ethyl-1-octanol, 2-methyl-3-heptanol, 1-decanol, 2-decanol, 3-decanol, 4-decanol, 5-decanol, 1-undecanol, 2-undecanol, 7-methyl-2-decanol, 1-dodecanol, 2-dodecanol, 2-ethyl-1-decanol and mixtures thereof having a boiling point higher than 170° C. (i.e., the boiling point of 1-decene) can be used.
[0083] In one embodiment of the present invention, the reaction mixture obtained in step (1) may be passed through a gas-liquid separator to recover unreacted ethylene before entering step (2), and the unreacted ethylene thus recovered may be reused in the ethylene oligomerization reaction in step (1).
[0084] In one embodiment of the present invention, in addition in step (2), C6 or less linear alpha olefins are separated from the reaction mixture obtained in step (1).
[0085] In one embodiment of the present invention, the C6 or lower linear alpha olefins separated in step (2) are further distilled.
[0086] In one embodiment, the C6 or lower linear alpha olefins may be further distilled by passing through more than one distillation column in sequence. Figure 1 and Figure 2 As shown, the C6 or lower linear alpha olefin stream discharged from the top of the distillation tower (400) is distilled by passing through three distillation towers (410, 420, 430) in sequence, so that ethylene, 1-butene and 1-hexene are collected from the top of each distillation tower, respectively, and the final residue (C6s, substances with a boiling point higher than 1-hexene) is discharged from the bottom of the final distillation tower (430).
[0087] In one embodiment, since the above-mentioned recovered ethylene stream may contain not only ethylene but also hydrogen, 1-butene, 1-hexene, solvent, etc., a constitution may be added for preventing an increase in the impurity content in the recovered material by discharging a portion of the recovered ethylene stream as off-gas.
[0088] In the method for preparing ethylene oligomers of the present invention, in step (3), the mixture containing the solvent and C8 or higher linear alpha olefins separated in step (2) is distilled in a dividing wall tower, so that the solvent is discharged from the top of the dividing wall tower, the C8 linear alpha olefins are discharged from the first side of the dividing wall tower, and the C10 or higher linear alpha olefins are discharged from the bottom of the dividing wall tower or from a side lower than the first side of the dividing wall tower.
[0089] The specific composition of the mixture fed to the dividing wall column, the specific configuration of the dividing wall column and the distillation conditions therein are the same as described above.
[0090] In one embodiment, the solvent discharged from the dividing wall column in the recovery step (3) is reused in the ethylene oligomerization reaction in step (1). The deoxidizer should not be recovered at this time.
[0091] In one embodiment, the C10 or higher linear alpha olefins discharged from the dividing wall column in step (3) are further distilled. The further distillation of the C10 or higher linear alpha olefins is the same as described above.
[0092] According to one embodiment, during the process of recovering the feedstock and solvent for the ethylene oligomerization reaction, a heat exchanger may be used to cool the recovered materials.
[0093] According to one embodiment, the resulting mixture of the ethylene oligomerization reaction may be passed through a filter to separate the polymer therefrom before being fed to the gas-liquid separator.
[0094] According to one embodiment, the C10 and above linear α-olefins discharged from the dividing wall column may be treated using a drum flaker or the like to separate low molecular weight polymers therefrom.
[0095] According to one embodiment, before the feedstock and solvent for ethylene oligomerization are introduced into the reactor, an adsorption column may be used for treatment so as to remove catalyst poisons such as moisture and oxygen. Such pretreatment process may generally be performed by an adsorption process.
[0096] The ethylene oligomerization reactor (a) included in the apparatus for preparing ethylene oligomers as the third aspect of the present invention may be a conventional reactor such as a stirred reactor, a tubular reactor or a continuously stirred tank reactor, and may have an ethylene injection section, a catalyst injection section and a solvent injection section, and may also have a recycled ethylene injection section. Two or more ethylene oligomerization reactors may be installed in a parallel configuration.
[0097] The first distillation column (b) included in the apparatus for preparing ethylene oligomers of the present invention may be a conventional distillation column, which is fluidically connected to the bottom of the ethylene oligomerization reactor and a gas-liquid separator may be provided therebetween. Two or more gas-liquid separators may be installed in parallel or in serial configuration.
[0098] In one embodiment, there may be an ethylene recovery line between the first distillation column and the ethylene oligomerization reactor fluidly connecting them.
[0099] In one embodiment, the top of the first distillation column may be fluidly connected to an additional device for distilling C6 and lower linear alpha olefins, such additional device may include a Figure 1 and Figure 2 The distillation column configuration (410, 420, 430) shown in FIG. 1 is a plurality of distillation columns, but is not limited thereto.
[0100] The dividing wall column (c) included in the apparatus for preparing ethylene oligomers of the present invention is fluidly connected to the bottom of the first distillation column, and separates the mixture containing the solvent and C8 or higher linear alpha olefins from the bottom of the first distillation column into the solvent, C8 linear alpha olefins and C10 or higher linear alpha olefins, respectively. The specific composition of the mixture fed to the dividing wall column, the specific configuration of the dividing wall column and the distillation conditions therein are the same as those described above.
[0101] In one embodiment, there may be an ethylene recovery line between the dividing wall column and the ethylene oligomerization reactor fluidly connecting them.
[0102] In one embodiment, the bottom of the dividing wall column may be fluidly connected to an additional device for distilling C10 or higher linear alpha olefins. Such additional device may include, for example, Figure 3 The distillation towers (610, 620, 630, 640) shown in the configuration or Figure 4 The dividing wall towers (510, 520) shown in the figure are configured with multiple dividing wall towers, but are not limited to this.
[0103] The following will be described in more detail with reference to the accompanying drawings, but the scope of the present invention is not limited by these drawings in any way.
[0104] Figure 1 The conventional process for ethylene oligomerization and product separation is schematically shown. In the process, ethylene, a catalyst and a solvent as raw materials are fed to an oligomerization reactor (100) and reacted; then the reaction product passes through a gas-liquid separator (200), is fed to a first distillation tower (400) and distilled therein, and is separated into an overhead stream containing linear alpha olefins below C6 and a bottom stream containing linear alpha olefins above C8. The top stream of the first distillation tower is distilled by passing through three distillation towers (410, 420, 430) in sequence, thereby collecting ethylene, 1-butene, and 1-hexene from the top of each distillation tower, respectively, and discharging C6s (substances with a boiling point higher than 1-hexene) from the bottom of the final distillation tower (430); the bottom stream of the first distillation tower is distilled by passing through two distillation towers (450, 460) in sequence, thereby collecting the recovered solvent and 1-octene from the top of each distillation tower, respectively, and discharging C10+ (a linear alpha olefin stream above C10) from the bottom of the final distillation tower (460). The recovered solvent is reintroduced into the reactor (100), and the unreacted ethylene is recovered from the gas-liquid separator (200) and the distillation towers (400, 410) and reintroduced into the reactor (100).
[0105] Figure 2 A process for ethylene oligomerization and product separation according to an embodiment of the present invention is schematically shown, which is similar to the process of FIG. 1 in terms of the oligomerization reaction, the distillation process in the first distillation column, and the distillation process of the top stream of the first distillation column. Figure 1 The process is the same as Figure 1 The difference of the process is that the bottom flow of the first distillation tower is distilled in a single dividing wall tower (500), so the solvent is discharged from the top of the dividing wall tower, the C8 linear α-olefin (1-octene) is discharged from the side of the dividing wall tower, and the C10 or higher linear α-olefin (C10+) is discharged from the bottom of the dividing wall tower.
[0106] Figure 3 and Figure 4 Schematically showing the same pair as above Figure 2 In the process shown, there is an embodiment of a process in which C10 or higher linear alpha olefins (C10+) discharged from the bottom of the dividing wall column (500) are further distilled.
[0107] The present invention is described in more detail by the following examples. However, the scope of the present invention is not limited by the examples in any form.
[0108] [Example]
[0109] Preparation example: Ethylene oligomerization and first separation of the reaction products
[0110] according to Figure 1 In the process shown, the ethylene oligomerization reaction and the first separation of the reaction products are carried out as follows.
[0111] In a tubular reactor (100) of 1.2 m in length and 2 inches in diameter, methylcyclohexane was used as solvent in the presence of a catalyst [(iPrN[P(C6H4-p-Si(nBu)3)2]2)-CrCl2] + [B(C6F5)4] - The ethylene oligomerization reaction was carried out in the presence of 1 μmol of ethylene and 200 μmol of triisobutylaluminum (Al / Cr ratio: 200). The pressure of the reactant ethylene was 35 kgf / cm 2 , the temperature is 40° C. Then, the mixture obtained by the oligomerization reaction is passed through a gas-liquid separator ( 200 ), introduced into a first distillation tower ( 400 ) and distilled therein.
[0112] As a result of gas chromatography (GC) analysis, the top stream discharged from the first distillation tower contained 73.0% by weight of ethylene, 2.4% by weight of C4 linear α-olefins, and 15.7% by weight of C6 linear α-olefins, and the bottom stream discharged from the first distillation tower contained 86.6% by weight of methylcyclohexane solvent, 11.9% by weight of C8 linear α-olefins, and 1.4% by weight of C10 or higher linear α-olefins.
[0113] Comparative Example
[0114] according to Figure 1 In the process shown, the top stream discharged from the first distillation tower obtained in the above preparation example is distilled by passing through three distillation towers (410, 420, 430) in sequence, thereby collecting ethylene, 1-butene and 1-hexene from the top of each distillation tower, respectively, and the bottom stream discharged from the first distillation tower is distilled by passing through two distillation towers (450, 460) in sequence, thereby collecting solvent and 1-octene from the top of each distillation tower, respectively. In order to cool the top stream of the distillation tower, industrial water with a temperature not exceeding 40° C. is used as cooling water, and a propylene cooler with an operating capacity of -35° C. is used.
[0115] The energy consumption of each distillation column (the consumption during distillation and the consumption during cooling of the top stream) was calculated, and when the total energy consumption was set to 100, the relative values thereof are shown in the following Table 1, and the purity and flow amount ratio of the obtained solvent and linear α-olefin are shown in the following Table 2.
[0116] [Table 1]
[0117]
[0118] [Table 2]
[0119]
[0120] Example
[0121] according to Figure 2 In the process shown, the top stream discharged from the first distillation tower obtained in the above preparation example is distilled by passing through three distillation towers (410, 420, 430) in sequence, thereby collecting ethylene, 1-butene and 1-hexene from the top of each distillation tower, respectively, and the bottom stream discharged from the first distillation tower passes through a dividing wall tower (500), wherein the solvent is separated and collected from the top of the dividing wall tower, C8 linear α-olefin (1-octene) is separated and collected from the side of the dividing wall tower, and C10 or more linear α-olefin (C10+) is separated and collected from the bottom of the dividing wall tower. The distillation in the dividing wall tower is carried out in a temperature range of 52° C. to 167° C. and a pressure range of 0.33 bar to 0.53 bar, specifically, under the conditions of 0.33 bar / 52° C. at the top, 0.45 bar / 95° C. at the side, and 0.53 bar / 167° C. at the bottom. To cool the top flow of the distillation column, industrial water having a temperature not exceeding 40° C. is used as cooling water, and a propylene cooler having an operating capacity of -35° C. is used if necessary.
[0122] The energy consumption of each distillation column (the consumption during distillation and the consumption during cooling of the top stream) was calculated, and when the total energy consumption was set to 100, its relative values are shown in the following Table 3, and the purity and flow ratio of the obtained solvent and linear α-olefin are shown in the following Table 4.
[0123] [Table 3]
[0124]
[0125] [Table 4]
[0126]
[0127] From the results in Tables 1 to 4 above, it can be confirmed that, in the embodiments of the present invention, linear α-olefin products of the same specifications as the comparative examples of the existing process can be produced, while the energy consumption is significantly reduced compared with the comparative examples (i.e., the total energy consumption is relatively reduced by 17.5% (= (100-82.5)%)).
[0128] Description of Reference Numerals
[0129] 100: Oligomerization Reactor
[0130] 200: Gas-liquid separator
[0131] 400, 410, 420, 430, 450, 460, 610, 620, 630, 640: Distillation tower
[0132] 500, 510, 520: Next door tower
[0133] 501, 511, 521: partition wall
Claims
1. A method for separating a mixture comprising a solvent and C8 or higher linear alpha olefins, the method comprising: A mixture containing a solvent having a boiling point lower than C8 linear alpha olefins, C8 linear alpha olefins and C10 or higher linear alpha olefins is distilled in a dividing wall tower to discharge the solvent from the top of the dividing wall tower, discharge the C8 linear alpha olefins from the first side of the dividing wall tower, and discharge the C10 or higher linear alpha olefins from the bottom of the dividing wall tower or a side lower than the first side of the dividing wall tower.
2. The method according to claim 1, wherein the solvent having a boiling point lower than C8 linear alpha olefin is selected from the group consisting of benzene, toluene, xylene, chlorobenzene, dichlorobenzene, pentane, hexane, heptane, methylcyclohexane, cyclohexane and combinations thereof.
3. The method according to claim 1, wherein the mixture comprises 50 wt% to 95 wt% of the solvent having a boiling point lower than C8 linear alpha olefin, 4 wt% to 40 wt% of the C8 linear alpha olefin, and 0.5 wt% to 10 wt% of the C10 or higher linear alpha olefin, based on a total of 100 wt% of the mixture. 4 . The method according to claim 1 , wherein the distillation in the dividing wall column is performed at a temperature of 40° C. to 250° C. and a pressure of 0.1 bar to 15 bar. The method according to claim 1 , wherein the C10 or higher linear α-olefin discharged from the dividing wall column is additionally distilled.
6. A method for preparing an ethylene oligomer, the method comprising the following steps: (1) carrying out ethylene oligomerization in a solvent having a boiling point lower than that of C8 linear alpha olefins; (2) separating a mixture comprising the solvent and C8 or higher linear alpha olefins from the reaction mixture obtained in step (1); and (3) distilling the mixture containing the solvent and C8 or higher linear alpha olefins separated in step (2) in a dividing wall tower to discharge the solvent from the top of the dividing wall tower, discharge the C8 linear alpha olefins from the first side of the dividing wall tower, and discharge the C10 or higher linear alpha olefins from the bottom of the dividing wall tower or a side lower than the first side of the dividing wall tower.
7. The method according to claim 6, wherein the solvent having a boiling point lower than C8 linear alpha olefin is selected from the group consisting of benzene, toluene, xylene, chlorobenzene, dichlorobenzene, pentane, hexane, heptane, methylcyclohexane, cyclohexane and combinations thereof.
8. The method according to claim 6, wherein in addition in step (2), unreacted ethylene is recovered and reused in the ethylene oligomerization reaction in step (1).
9. The method according to claim 6, wherein in step (2), linear alpha olefins below C6 are separated from the reaction mixture obtained in step (1).
10. The method according to claim 6, wherein the C6 or lower linear alpha olefin separated in step (2) is further distilled.
11. The method according to claim 6, wherein the mixture subjected to distillation in the dividing wall column in step (3) comprises 50 wt% to 95 wt% of the solvent having a boiling point lower than C8 linear alpha olefin, 4 wt% to 40 wt% of the C8 linear alpha olefin, and 0.5 wt% to 10 wt% of the C10 or higher linear alpha olefin, based on 100 wt% of the total of the mixture.
12. The method according to claim 6, wherein the distillation in the dividing wall column in step (3) is performed at a temperature of 40 to 250°C and a pressure of 0.1 to 15 bar.
13. The method according to claim 6, wherein the solvent discharged from the dividing wall column in the recovery step (3) is reused in the ethylene oligomerization reaction in the step (1).
14. The method according to claim 6, wherein the C10 or higher linear alpha olefin discharged from the dividing wall column in step (3) is further distilled.
15. A device for preparing ethylene oligomers, the device comprising: (a) an ethylene oligomerization reactor; (b) a first distillation column in fluid communication with the bottom portion of the ethylene oligomerization reactor; as well as (c) a dividing wall column in fluid communication with the bottom of the first distillation column, The device operates in the following manner: In the ethylene oligomerization reactor, the ethylene oligomerization reaction is carried out in a solvent having a boiling point lower than that of C8 straight-chain alpha olefins. The resulting mixture of the ethylene oligomerization reaction is discharged from the bottom of the ethylene oligomerization reactor and then fed to the first distillation column and distilled therein, As a result of the distillation in the first distillation column, a mixture containing the solvent and C8 or higher linear α-olefins is discharged from the bottom of the first distillation column, and then fed to the dividing wall column and distilled therein, and As a result of distillation in the dividing wall tower, the solvent is discharged from the top of the dividing wall tower, C8 linear α-olefins are discharged from the first side of the dividing wall tower, and C10 or higher linear α-olefins are discharged from the bottom of the dividing wall tower or the side lower than the first side of the dividing wall tower.
16. The apparatus of claim 15, further comprising an ethylene recovery line fluidly connecting the first distillation column and the ethylene oligomerization reactor.
17. The apparatus according to claim 15, further comprising a device for distilling C6 or lower linear alpha olefins in fluid communication with the top of the first distillation column.
18. The apparatus of claim 15, further comprising a solvent recovery line fluidly connecting the dividing wall column and the ethylene oligomerization reactor.
19. The apparatus according to claim 15, further comprising a device for distilling C10 and above linear alpha olefins in fluid communication with the bottom of the dividing wall column.