Separation method of mixture containing solvent and C4 or above straight-chain alpha-olefin, and method and device for preparing ethylene oligomer by using separation method

Abstract

The present invention relates to a method for separating a mixture containing a solvent and a C4 or higher linear alpha-olefin, and a method and an apparatus for preparing an ethylene oligomer by using the separation method, and more particularly, to a method for separating a mixture containing a solvent and a C4 or higher linear alpha-olefin, the present invention relates to a method for separating a mixture containing a solvent and a C4 or higher linear alpha-olefin generated after an ethylene oligomerization reaction into the solvent, a C6 or lower linear alpha-olefin and a C8 or higher linear alpha-olefin even through a single treatment, and a method and an apparatus for preparing an ethylene oligomer using the separation method.

Description

Technical Field

[0001] The present invention relates to a method for separating a mixture containing a solvent and linear α-olefins of C4 or higher, and a method and an apparatus for preparing ethylene oligomers by using the separation method. More specifically, the present invention relates to a method for separating a mixture containing a solvent and linear α-olefins of C4 or higher produced after an ethylene oligomerization reaction into a solvent, linear α-olefins of C6 or lower, and linear α-olefins of C8 or higher by a one-time treatment, and a method and an apparatus for preparing ethylene oligomers by using the separation method. Background Art

[0002] Linear alpha olefin (LAO), also known as linear alphaalkene, linear terminal olefins, linear terminalalkenes or normal alpha olefins, is mainly used as a raw material for various chemical processes such as comonomers in polymerization processes, precursors in aldehyde and / or carboxylic acid oxidation production processes, and starting materials in advanced olefin production processes. It can also be directly used as a raw material component of surfactants, lubricants, detergents, etc. In particular, among linear alpha olefins, 1-hexene and 1-octene are substances used as comonomers in large quantities 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 α-olefins are mainly synthesized by an ethylene oligomerization process using a Ziegler-type catalyst. The product of this ethylene oligomerization process is usually a (full range) mixture of linear α-olefins above C4 with an even number of carbon atoms (e.g., 1-butene, 1-hexene, 1-octene, 1-decene, etc.).

[0004] The product stream of this ethylene oligomerization process includes various linear α-olefins, unreacted ethylene and a solvent inert to the oligomerization reaction. These products are separated into individual linear α-olefins, unreacted ethylene and solvent through subsequent multiple distillation processes, and the separated ethylene and solvent are recovered for reuse.

[0005] In addition, when using C7 saturated hydrocarbons such as methylcyclohexane and heptane as an inert solvent to separate C8 linear alpha olefins, i.e., 1-octene, which is a key material, from the reaction products of the ethylene oligomerization process, the amount of solvent required 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 top of the tower, and C8 or higher linear alpha olefins are discharged from the bottom of the tower. These C8 or higher linear alpha olefins are then fed into a subsequent distillation tower and heated to recover 1-octene through the top of the tower, and C10 or higher linear alpha 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 economics because too much energy is required for separation, thereby increasing operating costs, and multiple distillation columns are required, thereby increasing initial equipment investment and equipment maintenance costs; in addition, the equipment becomes complicated, so the stability and efficiency of the process become poor, resulting in unstable quality and output of the final product. Summary of the invention

[0007]

Technical issues

[0008] The object of the present invention is to provide a method for separating a mixture of a solvent and linear α-olefins above C4 produced after an ethylene oligomerization reaction into a solvent, linear α-olefins below C6 and linear α-olefins above C8 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 linear α-olefins above C4, the method comprising:

[0011] A mixture containing a solvent having a boiling point higher than C6 linear α-olefins and lower than C8 linear α-olefins, linear α-olefins below C6, and linear α-olefins above C8 is distilled in a dividing wall column to discharge linear α-olefins below C6 from the top of the dividing wall column, discharge the solvent from a first side of the dividing wall column, and discharge linear α-olefins above C8 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 higher than that of C6 linear α-olefin and lower than that of C8 linear α-olefin can 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, can 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 higher than C6 linear α-olefins and lower than C8 linear α-olefins, 0.5 wt% to 10 wt% of linear α-olefins below C6, and 4 wt% to 40 wt% of linear α-olefins above C8, based on a total of 100 wt% of the mixture.

[0014] In one embodiment, the distillation in the dividing wall column may be carried out at a temperature of 50° C. to 250° C. and a pressure of 0.2 bar to 15 bar.

[0015] In one embodiment, each of the C6 or lower linear α-olefin and the C8 or higher linear α-olefin withdrawn from the dividing wall column is 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 higher than that of C6 linear α-olefins and lower than that of C8 linear α-olefins;

[0018] (2) removing unreacted ethylene from the reaction mixture obtained in step (1); and

[0019] (3) After removing unreacted ethylene in step (2), the resulting mixture is distilled in a dividing wall tower to discharge linear α-olefins of C6 or less from the top of the dividing wall tower, discharge the solvent from the first side of the dividing wall tower, and discharge linear α-olefins of C8 or more 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 higher than that of C6 linear α-olefin and lower than that of C8 linear α-olefin can 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, can be selected from the group consisting of benzene, toluene, xylene, chlorobenzene, dichlorobenzene, pentane, hexane, heptane, methylcyclohexane, cyclohexane, and combinations thereof.

[0021] In one embodiment, the unreacted ethylene removed in step (2) is recovered to be reused in the oligomerization reaction of ethylene in step (1).

[0022] In one embodiment, heat is transferred from the resulting mixture after removal of unreacted ethylene in step (2) to the resulting reaction mixture in step (1).

[0023] In one embodiment, the mixture distilled in the dividing wall column in step (3) may include 50 wt% to 95 wt% of a solvent having a boiling point higher than C6 linear α-olefins and lower than C8 linear α-olefins, 0.5 wt% to 10 wt% of linear α-olefins below C6, and 4 wt% to 40 wt% of linear α-olefins above C8, based on the total 100 wt% of the mixture.

[0024] In one embodiment, the distillation in the dividing wall column in step (3) may be performed at a temperature of 50° C. to 250° C. and a pressure of 0.2 bar to 15 bar.

[0025] In one embodiment, the solvent discharged from the dividing wall column in step (3) is recovered to be reused in the oligomerization reaction of ethylene in step (1).

[0026] In one embodiment, each of the C6 or lower linear α-olefin and the C8 or higher linear α-olefin discharged from the dividing wall column in step (3) is additionally distilled.

[0027] In one embodiment, heat is transferred from the fractionated product of linear alpha olefins above C8 to the fractionated product of linear alpha olefins below C6.

[0028] A third aspect of the present invention relates to a device for preparing ethylene oligomers, the device comprising:

[0029] (a) an 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 operation mode of the device is as follows:

[0033] In the ethylene oligomerization reactor, the ethylene oligomerization reaction is carried out in a solvent having a boiling point higher than that of C6 linear α-olefins and lower than that of C8 linear α-olefins.

[0034] A mixture obtained by 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 including the solvent and C4 or higher linear α-olefins is discharged from the bottom of the first distillation column, which is then fed to the dividing wall column and distilled therein, and

[0036] As a result of distillation in the dividing wall column, linear α-olefins below C6 are discharged from the top of the dividing wall column, the solvent is discharged from the first side of the dividing wall column, and linear α-olefins above C8 are 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 a means for heat transfer from the bottom effluent of the first distillation column to the bottom effluent of the ethylene oligomerization reactor.

[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 a device for distilling linear α-olefins below C6, which is fluidly connected to the top of the first distillation column; and a device for distilling linear α-olefins above C8, which is fluidly connected to the bottom of the dividing wall column or a side lower than the first side of the dividing wall column.

[0041] In one embodiment, the apparatus for preparing ethylene oligomers further comprises means for transferring heat from the fractionated products of linear α-olefins above C8 to the fractionated products of linear α-olefins below C6.

[0042] [Effects of the present invention]

[0043] According to the present invention, in the ethylene oligomerization reaction, compared with the existing conventional separation process, while producing products with the same process specifications as the existing process, the energy usage can be significantly reduced, and since the equipment becomes simplified, the cost of initial equipment investment and equipment maintenance can be reduced, thereby having advantages in terms of economy, and also having the effect of improving process stability and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Corresponding to the comparative example of the present invention, the existing conventional process for ethylene oligomerization and product separation is schematically shown.

[0045] Figure 2Corresponding 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.

[0046] Figure 3 Schematically shows Figure 2 A more preferred embodiment of the process shown further includes a device for transferring heat from the bottom effluent of the first distillation tower to the bottom effluent of the ethylene oligomerization reactor, and a device for transferring heat from the top flow of the C8 linear α-olefin fractionation tower to the bottom flow of the C6 linear α-olefin fractionation tower.

[0047] Figure 4 Schematically showing further distillation from Figure 2 and Figure 3 An embodiment of a process for producing C10 and above linear alpha olefins (C10+) discharged in the process is shown.

[0048] Figure 5 Schematically showing further distillation from Figure 2 and Figure 3 Another embodiment of the process for producing C10+ linear alpha olefins discharged during the process is shown. DETAILED DESCRIPTION

[0049] The present invention will be described in more detail below.

[0050] As used herein, the term "linear alpha-olefin" (LAO) refers to a straight chain olefin compound having a terminal unsaturated double bond.

[0051] As used herein, the term "oligomer of ethylene" or "ethylene oligomer" refers to a linear α-olefin (chemical formula C 2n H 4n , wherein n is a positive integer greater than 2), for example, it may be 1-butene, 1-hexene, 1-octene or 1-decene, but is not limited thereto.

[0052] In the symbols used in this article, "Cx" represents a straight-chain α-olefin (or ethylene oligomer) having x carbon atoms, "Cx-" represents a straight-chain α-olefin having less than x carbon atoms, and "Cx+" represents a straight-chain α-olefin having more than x carbon atoms. For example, "C8" is a straight-chain α-olefin having 8 carbon atoms, namely 1-octene, "C8-" is a straight-chain α-olefin having less than 8 carbon atoms, namely including 1-butene, 1-hexene and 1-octene, and "C8+" is a straight-chain α-olefin having more than 8 carbon atoms, namely including 1-octene, 1-decene, 1-dodecene, etc.

[0053] 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 walls. If a mixture is distilled in a dividing wall column, three or more distillation product streams are discharged, wherein the lightest stream (with the lowest boiling point) is discharged from the top of the dividing wall column, the heaviest stream (with the highest boiling point) is discharged from the bottom of the dividing wall column, and the intermediate stream 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-wall column, in which case three distillation product streams (top / side / bottom) are discharged. If there are more than two dividing walls, it is called a multi-wall column, in which case four or more distillation product streams are discharged. For example, if a double-wall column has two dividing walls, four distillation product streams (top / first side / second side / bottom) are discharged. This specification Figure 2 , Figure 3 and Figure 5 Single dividing wall columns (500, 510, 520) are shown.

[0054] In one embodiment of the present invention, the solvent having a boiling point higher than that of C6 linear α-olefins and lower than that of C8 linear α-olefins can 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, can be selected from the group consisting of benzene, toluene, xylene, chlorobenzene, dichlorobenzene, pentane, hexane, heptane, methylcyclohexane, cyclohexane, and a combination thereof, more specifically, can be selected from the group consisting of methylcyclohexane, cyclohexane, heptane, and a combination thereof, preferably can be methylcyclohexane.

[0055] In one embodiment of the present invention, the mixture distilled in the dividing wall column may include 50 wt% to 95 wt% of a solvent having a boiling point higher than C6 linear α-olefins and lower than C8 linear α-olefins, 0.5 wt% to 10 wt% of linear α-olefins below C6, and 4 wt% to 40 wt% of linear α-olefins above C8, based on the total 100 wt% of the mixture.

[0056] 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 pipeline due to excessive oligomerization and the resulting polymer; conversely, if the content of the solvent is more than 95 wt %, there may be a problem of decreased productivity due to insufficient production of C8 and an increase in the ratio of C4 and C6.

[0057] 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.

[0058] Furthermore, more specifically, the content of C6 or lower 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.

[0059] Furthermore, more specifically, the content of C8 or higher 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.

[0060] In one embodiment of the present invention, the distillation in the dividing wall column may be performed at a temperature of 50° C. to 250° C. and a pressure of 0.2 bar to 15 bar.

[0061] If the temperature during distillation in the dividing wall column is lower than 50° C., all components may not be distilled but discharged through the bottom and the top of the distillation column may be dried up; on the contrary, if the temperature is higher than 250° C., all components may be distilled and discharged through the top and the bottom of the distillation column may be dried up. In addition, if the pressure during distillation in the dividing wall column is lower than 0.2 bar, the boiling point of the fluid may be lowered, so that separation cannot be performed normally, and the solvent may be discharged from the overhead, resulting in a problem of reduced quality of the 1-hexene product; on the contrary, if the pressure is higher than 15 bar, the boiling point of the fluid may be increased to more than 250° C., so that distillation cannot be performed normally, resulting in a problem of reduced quality of the 1-octene product, reduced purity of the solvent discharged from the side, or loss due to the solvent discharged from the bottom not being recycled.

[0062] More specifically, the temperature conditions during distillation in the dividing wall tower can be above 55°C, above 60°C, above 65°C, above 70°C, above 75°C, above 80°C, above 85°C or above 90°C, and can also be below 250°C, below 240°C, below 220°C, below 200°C, below 180°C or below 160°C, but are not limited thereto.

[0063] In addition, more specifically, the pressure conditions during distillation in the dividing wall tower can be above 0.3 bar, above 0.4 bar, above 0.5 bar or above 0.6 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 3.5 bar, below 3 bar, below 2.5 bar, below 2 bar or below 1.5 bar, but are not limited thereto.

[0064] In one embodiment of the present invention, at the top of the dividing wall tower, the temperature condition can be above 60°C, above 70°C or above 80°C, and can also be below 200°C, below 150°C or below 120°C, but not limited thereto, and the pressure condition can be above 0.5 bar, above 0.7 bar or above 0.9 bar, and can also be below 3 bar, below 2.5 bar, below 2 bar or below 1.5 bar, but not limited thereto.

[0065] In one embodiment of the present invention, on the side of the dividing wall tower, the temperature condition can be above 60°C, above 70°C or above 80°C, and can also be below 200°C, below 150°C or below 120°C, but are not limited thereto, and the pressure condition can be above 0.5 bar, above 0.7 bar or above 0.9 bar, and can also be below 3 bar, below 2.5 bar, below 2 bar or below 1.5 bar, but are not limited thereto.

[0066] In one embodiment of the present invention, at the bottom of the dividing wall tower, the temperature condition may be above 80°C, above 90°C or above 100°C, and may also be below 250°C, below 200°C or below 150°C, but not limited thereto, and the pressure condition may be above 0.5 bar, above 0.7 bar or above 0.9 bar, and may also be below 15 bar, below 10 bar, below 5 bar, below 3 bar, below 2.5 bar, below 2 bar or below 1.5 bar, but not limited thereto.

[0067] In one embodiment, each of the C6 or lower linear α-olefin and the C8 or higher linear α-olefin withdrawn from the dividing wall column is additionally distilled.

[0068] In one embodiment, the C6 or lower linear α-olefins may be additionally distilled by sequentially passing through more than one distillation column. Figure 2 and Figure 3As shown, the linear α-olefin stream below C6 discharged from the top of the dividing wall tower (500) is distilled by passing through two distillation towers (420, 430) in sequence, so that 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).

[0069] In addition, in one embodiment, the linear α-olefins above C8 can be additionally distilled by passing through more than one distillation tower in sequence. Figure 2 and Figure 3 As shown, the C8 or higher linear α-olefin stream discharged from the bottom of the dividing wall tower (500) is distilled in the distillation tower (460), so that 1-octene is collected from the top of the tower and C10 or higher linear α-olefins (C10+) are discharged from the bottom.

[0070] In addition, in one embodiment, the linear α-olefins above C10 can be additionally distilled by passing through more than one distillation tower in sequence. Figure 4 As shown, the C10+ linear α-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 5 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 distillation tower (510), respectively, C14 and C16 are collected from the top and side of the distillation tower (520), respectively, and the final residue C18+ is discharged from the bottom of the final distillation tower (520).

[0071] In the method for preparing ethylene oligomers as the second aspect of the present invention, in step (1), ethylene oligomerization is carried out in a solvent having a boiling point higher than that of C6 linear α-olefins and lower than that of C8 linear α-olefins.

[0072] The solvent having a boiling point higher than that of the C6 linear α-olefin and lower than that of the 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.

[0073] 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.

[0074] [Chemical formula 1]

[0075]

[0076] In the above chemical formula 1,

[0077] R is a C1-C60 alkyl group or a C6-C60 aryl group;

[0078] R 1 -R 4 Each is independently a C1-C60 alkyl group or a C6-C60 aryl group;

[0079] X 1 and X 2 Each independently is a C1-C30 hydrocarbon group selected from one or more of halogen, C1-C30 alkyl, C1-C30 alkylcarboxylate, acetylacetonate, ether and amino;

[0080] A is boron or aluminum;

[0081] 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

[0082] 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.

[0083] In addition, the method of oligomerizing ethylene is not particularly limited. For example, as disclosed in Korean Patent Laid-Open No. 10-2022-0087986, ethylene oligomerization can be carried out at an ethylene pressure of 0-100 kgf / cm 2and the reaction temperature is 0°C-150°C. More specifically, the reaction can be carried out at an ethylene pressure of 20 kgf / cm 2 -80kgf / cm 2 and the reaction temperature is 20°C-120°C. More specifically, the ethylene pressure can be 30 kgf / cm 2 -60kgf / cm 2 The reaction is carried out at a temperature of 40°C to 100°C, but is not limited thereto.

[0084] 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.

[0085] In one embodiment of the invention, after the ethylene oligomerization reaction in step (1), a deoxidant (killing agent) is added to the resulting reaction mixture immediately 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, but is not limited thereto.

[0086] Preferably, in order to prevent the deoxidizer from being recovered together in the solvent recovery process, one or more selected from the group consisting of 1-octanol, 1-decanol, 1-dodecanol, 2-ethyl-1-hexanol, 2-methyl-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 and 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.

[0087] In one embodiment of the present invention, the reaction mixture obtained in step (1) can be used to recover unreacted ethylene through a gas-liquid separator before entering step (2), and the unreacted ethylene recovered in this way can be reused in the ethylene oligomerization reaction in step (1).

[0088] In one embodiment of the present invention, in step (2), unreacted ethylene is removed from the reaction mixture obtained in step (1).

[0089] In one embodiment of the present invention, the unreacted ethylene removed in step (2) is recovered to be reused in the oligomerization reaction of ethylene in step (1).

[0090] In one embodiment of the present invention, since the above-mentioned recovered ethylene stream contains not only ethylene but also hydrogen, 1-butene, 1-hexene, solvent, etc., a constitution can be added to prevent an increase in the impurity content in the recovered material by discharging a portion of the recovered ethylene stream as off-gas.

[0091] In a preferred embodiment of the present invention, after removing unreacted ethylene in step (2), heat is transferred from the resulting mixture to the reaction mixture of step (1). This can be achieved by a suitable heat transfer means, such as those described in this specification. Figure 3 The heat exchanger (415) shown in FIG. 4 is used to further reduce energy consumption.

[0092] In the method for preparing ethylene oligomers of the present invention, in step (3), the mixture obtained after removing the unreacted ethylene in step (2) is distilled in a dividing wall tower, so that α-straight-chain olefins below C6 are discharged from the top of the dividing wall tower, the solvent is discharged from the first side of the dividing wall tower, and α-straight-chain olefins above C8 are discharged from the bottom of the dividing wall tower or the side lower than the first side of the dividing wall tower.

[0093] The specific composition of the mixture fed to the dividing wall column, the specific structure of the dividing wall column and the distillation conditions thereof are the same as those described above.

[0094] In one embodiment, the solvent discharged from the dividing wall column in step (3) is recovered to be reused in the oligomerization reaction of ethylene in step (1). In this case, the deoxidizer should not be recovered.

[0095] In one embodiment, each of the C6 or lower linear α-olefins and the C8 or higher linear α-olefins discharged from the dividing wall column in step (3) is additionally distilled. The additional distillation of the C6 or lower linear α-olefins and the C8 or higher linear α-olefins is the same as described above.

[0096] In a preferred embodiment of the present invention, heat is transferred from the fractional distillation product of linear α-olefins above C8 to the fractional distillation product of linear α-olefins below C6. This can be achieved by a proper means for heat transfer, such as the one described in the specification. Figure 3 The reflux (461), reboiler (431) and heat exchange flow (465) shown in the figure can further reduce energy consumption.

[0097] According to one embodiment, in the process of recovering the feedstock and the solvent for the ethylene oligomerization reaction, a heat exchanger may be used to cool the recovered feedstock.

[0098] According to one embodiment, the mixture obtained from the ethylene oligomerization reaction may be separated from the polymer therein by passing through a filter before being fed to the gas-liquid separator.

[0099] According to one embodiment, C10 and above linear α-olefins discharged as a result of fractional distillation of C8 and above linear α-olefins may be treated using a drum flaker or the like to separate low molecular weight polymers therefrom.

[0100] According to one embodiment, before the feedstock and solvent for ethylene oligomerization are introduced into the reactor, they can be treated using an adsorption tower to remove catalyst poisons such as moisture and oxygen. This pretreatment process can generally be performed by an adsorption process.

[0101] The ethylene oligomerization reactor (a) included in the apparatus for preparing ethylene oligomers as the third aspect of the present invention can be a conventional reactor, such as a stirred reactor, a tubular reactor or a continuously stirred tank reactor, and can have an ethylene injection section, a catalyst injection section and a solvent injection section, and can also have a recycled ethylene injection section. Two or more ethylene oligomerization reactors can be installed in a parallel configuration.

[0102] 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 placed in the middle. Two or more gas-liquid separators may be installed in parallel or in series.

[0103] In one embodiment, between the first distillation column and the ethylene oligomerization reactor, there may be an ethylene recovery line fluidly connecting them.

[0104] In a preferred embodiment, the apparatus for preparing ethylene oligomers may further include a device for transferring heat from the bottom effluent of the first distillation column to the bottom effluent of the ethylene oligomerization reactor, such as Figure 3 In this case, the bottom effluent of the ethylene oligomerization reactor passes through the heat exchanger (415) and is fed to the first distillation column, and the bottom effluent of the first distillation column passes through the heat exchanger (415) and is fed to the dividing wall column.

[0105] The dividing wall column (c) included in the apparatus for producing ethylene oligomers of the present invention is fluidically connected to the bottom of the first distillation column, and separates the mixture containing the solvent and C4 or higher linear α-olefins from the bottom of the first distillation column into the solvent, C6 or lower linear α-olefins, and C8 or higher linear α-olefins, respectively. The specific composition of the mixture fed to the dividing wall column, and the specific construction of the dividing wall column and its distillation conditions are the same as those described above.

[0106] In one embodiment, between the dividing wall column and the ethylene oligomerization reactor, there may be a solvent recovery line fluidly connecting them.

[0107] In one embodiment, the top of the dividing wall column may be fluidly connected to an additional device for distilling linear α-olefins below C6, and such additional device may include a plurality of Figure 2 and Figure 3 The distillation columns (420, 430) are shown as distillation columns in configurations, but are not limited thereto.

[0108] In one embodiment, the bottom of the dividing wall column may be fluidly connected to an additional device for distilling linear α-olefins above C8, and such additional device may include a plurality of such as Figure 2 and Figure 3 The distillation tower (460) shown in the figure is configured and connected in sequence to the distillation tower at the bottom thereof. Figure 4 The distillation tower (610, 620, 630, 640) shown or Figure 5 Distillation columns (510, 520) are shown, but are not limited thereto.

[0109] In a preferred embodiment, the device for preparing ethylene oligomers may also include a device for transferring heat from the fractionation products of linear α-olefins above C8 to the fractionation products of linear α-olefins below C6, for example, Figure 3reflux (461), reboiler (431) and heat exchange stream (465) shown in the figure; in this case, the top stream of the fractionation distillation tower of C8 linear α-olefin passes through the reflux (415) and releases heat, and then the heat is provided to the reboiler (431) through the heat exchange stream (465), and is transferred to the bottom stream of the fractionation tower of C6 linear α-olefin, and then reintroduced into the fractionation tower.

[0110] 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.

[0111] Figure 1 The general process for the existing ethylene oligomerization and product separation is schematically shown, in which 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), and is fed to a first distillation tower (400) and distilled therein, and is separated into a tower top stream containing linear α-olefins below C6 and a tower bottom stream containing linear α-olefins above C8 and discharged; then, the tower top stream of the first distillation tower passes through three distillation towers in sequence. The first distillation tower is distilled by distilling the first distillation tower (410, 420, 430), thereby collecting ethylene, 1-butene and 1-hexene from the top of each distillation tower, 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 α-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).

[0112] Figure 2 A process for ethylene oligomerization and product separation according to an embodiment of the present invention is schematically shown, in which the Figure 1The reaction product after the same ethylene oligomerization reaction and gas-liquid separation process is distilled in the first distillation tower to produce a bottom stream containing solvent and linear α-olefins above C4. The bottom stream of the first distillation tower is distilled in a single dividing wall tower (500), and linear α-olefins below C6 are discharged from the top of the dividing wall tower, the solvent is discharged from the side of the dividing wall tower, and linear α-olefins above C8 (C8+) are discharged from the bottom of the dividing wall tower. After that, the top stream of the dividing wall tower is distilled by passing through two distillation towers (420, 430) in sequence, so that 1-butene and 1-hexene are collected from the top of each distillation tower, respectively, and C6s (substances with a boiling point higher than 1-hexene) are discharged from the bottom of the final distillation tower (430); the bottom stream of the dividing wall tower is distilled in a distillation tower (460), so that 1-octene is collected from the top of the tower, and C10+ (linear α-olefin stream above C10) is discharged from the bottom. The recovered solvent is reintroduced into the reactor (100), and furthermore, unreacted ethylene is recovered from the gas-liquid separator (200) and the distillation column (400) and reintroduced into the reactor (100).

[0113] Figure 3 Schematically shows Figure 2 A more preferred embodiment of the process shown further includes a device for transferring heat from the bottom effluent of the first distillation tower to the bottom effluent of the ethylene oligomerization reactor (heat exchanger (415)), and a device for transferring heat from the top flow of the C8 linear α-olefin fractionation tower to the bottom flow of the C6 linear α-olefin fractionation tower (reflux (461), reboiler (431) and heat exchange flow (465)).

[0114] Figure 4 and Figure 5 Schematically shows the Figure 2 or Figure 3 An embodiment of the process for further distilling C10 and above linear α-olefins (C10+) in the process shown is the same as described above.

[0115] 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.

[0116] [Example]

[0117] Comparative Example

[0118] according to Figure 1 The process shown, ethylene oligomerization and separation of the reaction products are as follows.

[0119] In a tubular reactor (100) having a length of 1.2 m and a diameter of 2 inches, methylcyclohexane was used as a solvent and a catalyst [(iPrN[P(C 6 H 4 -p-Si(nBu)3 ) 2 ] 2 )-CrCl 2 ] + [B(C 6 F 5 ) 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.

[0120] 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.

[0121] Then, the top stream discharged from the first distillation tower is sequentially distilled through three distillation towers (410, 420, 430), thereby collecting ethylene, 1-butene and 1-hexene from the top streams of the distillation towers, respectively, and the bottom stream discharged from the first distillation tower is sequentially distilled through two distillation towers (450, 460), and the recovered solvent and 1-octene are collected from the top of each distillation tower. 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.

[0122] The energy consumption of each distillation tower (the consumption during distillation and the consumption during cooling of the top stream) was calculated. When the total energy consumption was set to 100, the relative values ​​were shown in Table 1 below. The purity and flow amount ratio of the obtained solvent and linear α-olefin are shown in Table 2 below.

[0123] [Table 1]

[0124]

[0125] [Table 2]

[0126]

[0127] Example 1

[0128] according to Figure 2In the process shown, the ethylene oligomerization and separation of the reaction products proceed as follows.

[0129] In a tubular reactor (100) having a length of 1.2 m and a diameter of 2 inches, methylcyclohexane was used as a solvent and a catalyst [(iPrN[P(C 6 H 4 -p-Si(nBu) 3 ) 2 ] 2 )-CrCl 2 ] + [B(C 6 F 5 ) 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 produced by the oligomerization reaction is passed through a gas-liquid separator ( 200 ), introduced into a first distillation tower ( 400 ) and distilled therein.

[0130] As a result of gas chromatography (GC) analysis, the bottom stream discharged from the first distillation column contained 83.7% by weight of methylcyclohexane solvent, 0.3% by weight of C4 linear α-olefins, 2.1% by weight of C6 linear α-olefins, 11.5% by weight of C8 linear α-olefins, and 1.3% by weight of C10 or higher linear α-olefins.

[0131] The bottom stream discharged from the above-mentioned first distillation column passes through a dividing wall column (500), wherein linear α-olefins below C6 are separated and discharged from the top of the dividing wall column, the solvent is separated and discharged from the side of the dividing wall column, and linear α-olefins above C8 (C8+) are separated and discharged from the bottom of the dividing wall column. The distillation in the dividing wall column is carried out in a temperature range of 102° C. to 127° C. and a pressure range of 1 bar to 1.1 bar, specifically, under the conditions of 1.0 bar / 102° C. at the top, 1.03 bar / 102° C. at the side, and 1.1 bar / 127° C. at the bottom. In order to cool the top stream 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 as necessary.

[0132] Then, the top stream discharged from the dividing wall tower is distilled by passing through two distillation towers (420, 430) in sequence, thereby collecting 1-butene and 1-hexene from the top streams of the respective distillation towers, respectively, and the bottom stream of the dividing wall tower is distilled in the distillation tower (460), thereby collecting C8 linear α-olefin (1-octene) from the top of the distillation tower, and a linear α-olefin stream (C10+) of C10 or more is discharged from the bottom of the distillation tower. 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.

[0133] The energy consumption of each distillation column (the consumption during distillation and the consumption during cooling of the top flow) was calculated. When the total energy consumption was set to 100, the relative values ​​were shown in Table 3 below. The purity and flow ratio of the obtained solvent and linear α-olefin are shown in Table 4 below.

[0134] [Table 3]

[0135]

[0136] [Table 4]

[0137]

[0138] From the results of Tables 1 to 4 above, it can be confirmed that in Example 1 of the present invention, a linear α-olefin product with the same specifications as the comparative example of the existing process can be produced, and at the same time, compared with the comparative example, the energy consumption is reduced (that is, the total energy consumption is relatively reduced by 4% (=100-96)).

[0139] Example 2

[0140] according to Figure 3 The process shown in Example 1 is to carry out the ethylene oligomerization reaction and the separation process of the reaction products. That is, the same process as Example 1 is carried out except that a device for transferring heat from the bottom effluent of the first distillation column to the bottom effluent of the ethylene oligomerization reactor (heat exchanger (415)) and a device for transferring heat from the top flow of the C8 linear α-olefin fractionation column to the bottom flow of the C6 linear α-olefin fractionation column (reflux (461), reboiler (431) and heat exchange stream (465)) are added to the process of Example 1. Only the top of the distillation column (420) for 1-butene separation is cooled using brine.

[0141] The energy consumption of each distillation column (the consumption during distillation and the consumption during cooling of the top flow) was calculated. When the total energy consumption was set to 100, the relative values ​​were shown in Table 5 below. The purity and flow ratio of the obtained solvent and linear α-olefin are shown in Table 6 below.

[0142] [Table 5]

[0143]

[0144] *Result of heat exchange between the distillation column for 1-hexene separation and the distillation column for 1-octene separation

[0145] [Table 6]

[0146]

[0147] From the results of Tables 1, 2, 5 and 6 above, it can be confirmed that in Example 2 of the present invention, a linear α-olefin product with the same specifications as the comparative example of the existing process can be produced, and at the same time, compared with the comparative example, the energy consumption is significantly reduced (that is, the total energy consumption is relatively reduced by 17.9% (=100-82.1)).

[0148] [Description of Reference Numerals]

[0149] 100: Oligomerization Reactor

[0150] 200: Gas-liquid separator

[0151] 400, 410, 420, 430, 450, 460, 610, 620, 630, 640: distillation tower

[0152] 500, 510, 520: Next door tower

[0153] 501, 511, 521: partition wall

[0154] 415: Heat exchanger

[0155] 461: Reflux

[0156] 431: Reboiler

[0157] 465: Heat exchange flow from reflux (461) to reboiler (431)

Claims

1. A method for separating a mixture comprising a solvent and linear α-olefins above C4, the method comprising: A mixture comprising a solvent having a boiling point higher than C6 linear α-olefins and lower than C8 linear α-olefins, linear α-olefins below C6, and linear α-olefins above C8 is distilled in a dividing wall tower to discharge the linear α-olefins below C6 from the top of the dividing wall tower, discharge the solvent from the first side of the dividing wall tower, and discharge the linear α-olefins above C8 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 higher than C6 linear α-olefins and lower than C8 linear α-olefins 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 includes 50 wt % to 95 wt % of the solvent having a boiling point higher than C6 linear α-olefin and lower than C8 linear α-olefin, 0.5 wt % to 10 wt % of linear α-olefin below C6, and 4 wt % to 40 wt % of linear α-olefin above C8, based on the total 100 wt % of the mixture.

4. The process according to claim 1, wherein the distillation in the dividing wall column is carried out at a temperature of 50°C to 250°C and a pressure of 0.2 bar to 15 bar. 5 . The method according to claim 1 , wherein each of the C6 or lower linear α-olefin and the C8 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 higher than that of C6 linear α-olefins and lower than that of C8 linear α-olefins; (2) removing unreacted ethylene from the reaction mixture obtained in step (1); as well as (3) After removing unreacted ethylene in step (2), the resulting mixture is distilled in a dividing wall tower to discharge linear α-olefins below C6 from the top of the dividing wall tower, discharge the solvent from the first side of the dividing wall tower, and discharge linear α-olefins above C8 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 higher than C6 linear α-olefins and lower than C8 linear α-olefins 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 the unreacted ethylene removed in step (2) is recovered to be reused in the oligomerization reaction of ethylene in step (1).

9. The method according to claim 6, wherein heat is transferred from the mixture obtained after removing unreacted ethylene in step (2) to the reaction mixture obtained in step (1).

10. The method according to claim 6, wherein the mixture to be distilled in the dividing wall column in step (3) comprises 50 wt% to 95 wt% of the solvent having a boiling point higher than C6 linear α-olefins and lower than C8 linear α-olefins, 0.5 wt% to 10 wt% of linear α-olefins below C6, and 4 wt% to 40 wt% of linear α-olefins above C8, based on 100 wt% of the total of the mixture.

11. The method according to claim 6, wherein the distillation in the dividing wall column in step (3) is carried out at a temperature of 50°C to 250°C and a pressure of 0.2 bar to 15 bar.

12. The method according to claim 6, wherein the solvent discharged from the dividing wall column in step (3) is recovered to be reused in the oligomerization reaction of ethylene in step (1).

13. The method according to claim 6, wherein each of the C6 or lower linear α-olefin and the C8 or higher linear α-olefin discharged from the dividing wall column in step (3) is additionally distilled.

14. The method according to claim 13, wherein heat is transferred from the fractionated product of the linear α-olefins above C8 to the fractionated product of the linear α-olefins below C6.

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 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 operation mode of the device is: In the ethylene oligomerization reactor, ethylene oligomerization reaction is carried out in a solvent having a boiling point higher than that of C6 linear α-olefin and lower than that of C8 linear α-olefin, The mixture obtained by the ethylene oligomerization reaction is discharged from the bottom of the ethylene oligomerization reactor, and then fed to the first distillation tower for distillation. As a result of the distillation in the first distillation column, a mixture including the solvent and C4 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 the distillation in the dividing wall tower, linear α-olefins below C6 are discharged from the top of the dividing wall tower, the solvent is discharged from the first side of the dividing wall tower, and linear α-olefins above C8 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 of claim 15, further comprising means for transferring heat from the bottom effluent of the first distillation column to the bottom effluent of the ethylene oligomerization reactor.

18. The apparatus of claim 15, further comprising a solvent recovery line fluidly connecting the dividing wall column with the ethylene oligomerization reactor.

19. The apparatus according to claim 15, further comprising a device for distilling linear α-olefins below C6, which is fluidly connected to the top of the first distillation column; and a device for distilling linear α-olefins above C8, which is fluidly connected to the bottom of the dividing wall column or a side lower than the first side of the dividing wall column.

20. The apparatus according to claim 19, further comprising a device for transferring heat from the fractionated product of linear α-olefins above C8 to the fractionated product of linear α-olefins below C6.

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