JP2013231015A - Method for producing olefin oligomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an olefin oligomer, in which setting of a distillation temperature becomes easier than that of a conventional method while controlling increase of a light component mixed with a final product.SOLUTION: A method for producing an olefin oligomer, which includes a step of collecting the olefin oligomer (N) from a polymerization solution, wherein the collection step comprises: a first distillation step of separating the polymerization solution into a first fraction that is a portion of the low-molecular-weight component (N-) and a second fraction (a bottom product) that is composed of the remainder of the low-molecular-weight component (N-), the olefin oligomer (N) and an olefin oligomer (N+); a second distillation step of separating a fourth fraction (a bottom product) mainly composed of the olefin oligomer (N+) from the second fraction (the bottom product) to produce a third fraction; and a third distillation step of separating a fifth fraction mainly composed of the low-molecular-weight component (N-) from the third fraction to collect the olefin oligomer (N) in a sixth fraction (a bottom product).

Description

  The present invention relates to a method for producing an olefin oligomer. More specifically, the present invention relates to a method for producing an olefin oligomer having a step of separating an olefin oligomer having a desired polymerization degree from a polymerization liquid containing olefin oligomers having different polymerization degrees.

  Alpha-olefin oligomers having 4 to 28 carbon atoms are mainly produced as raw materials for synthetic lubricating oils such as engine oils. Among these α-olefin oligomers, a synthetic lubricating oil mainly composed of an oligomer of 1-decene and an oligomer of 1-octene and 1-dodecene is extremely useful as a raw material oil for high-performance engine oils. Demand is increasing.

  As a method for producing a lubricating oil base material, Patent Document 1 describes that an α-olefin is polymerized using a metallocene catalyst. The polymerization liquid obtained by polymerizing the α-olefin contains oligomers having different degrees of polymerization. From this polymerization solution, an oligomer having a desired viscosity (degree of polymerization) is recovered by separation by distillation.

By the way, when the oligomer (referred to as oligomer N) having a desired degree of polymerization is separated from the polymerization solution by distillation, the oligomer N has conventionally been recovered by the following distillation steps (1) and (2).
(1) The polymerization solution is separated into a component N- (including the raw material monomer) having a polymerization degree lower than that of the oligomer N and a component having a polymerization degree equal to or higher than that of the oligomer N.
(2) The component having a polymerization degree equal to or higher than that of the oligomer N obtained in the distillation step (1) is separated into the oligomer N and other components, that is, the oligomer N + having a higher polymerization degree than the oligomer N.

In the conventional method, when the polymerization solution is completely separated into two components in the distillation step (1) above, since the allowable range of the optimum distillation temperature is very narrow, the distillation temperature differs only by a few degrees C. There was a problem that the amount of the oligomer N occupied in the obtained separated product greatly fluctuated.
For example, when a 1-decene dimer is recovered from a polymerization solution, many dimer components are mixed into a component (unreacted monomer) having a low degree of polymerization only by being about 2 ° C. higher than the optimum temperature. On the other hand, if the temperature is set low in order to reduce the evaporation of the dimer component, a large amount of unreacted monomer remains without being evaporated.
Since the optimum temperature for distillation varies depending on the composition of the polymerization solution, at present, the composition of the polymerization solution is measured by gas chromatography (GC), and based on the evaporation temperature of oligomer N, the pressure, the composition of the polymerization solution, etc. It is set.

  In the distillation step (2), the oligomer N is evaporated, so that the distillation temperature becomes high. For this reason, a part of the processing target is thermally decomposed to produce a light component. The light component having 16 or less carbon atoms is called a volatile organic compound (VOC) and has a problem of causing health damage. Unsaturated hydrocarbons are odorous. For this reason, there is a problem in that the product value decreases when light components are mixed into the final product.

JP 2009-149911 A

  The object of the present invention is to obtain not only unreacted and low-polymerization components contained in the polymerization liquid, but also the heat of the distillation treatment when light and heavy removal are performed by distillation to obtain a product having a single polymerization degree. An object of the present invention is to provide a method for producing an olefin oligomer in which the distillation temperature can be easily set as compared with the conventional method while efficiently removing light components generated by decomposition.

As a result of intensive studies, the present inventors have found that by making the distillation process into three steps, the allowable range of the distillation temperature can be expanded and the light amount mixed into the final product can be reduced, and the present invention has been completed. .
According to the present invention, the following olefin oligomer production methods and the like are provided.
1. An olefin oligomer N having a polymerization degree of N (N is 2 or more) by polymerizing an olefin having 4 to 28 carbon atoms, a component N- having a lower molecular weight than the olefin oligomer N, and the olefin oligomer Producing a polymerization liquid containing an olefin oligomer N + having a higher degree of polymerization than N;
A method for producing an olefin oligomer, comprising a step of recovering the olefin oligomer N from the polymerization solution,
In the recovery step, the polymerization liquid is divided into a first fraction which is a part of the low molecular weight component N−, a second fraction comprising the remainder of the low molecular weight component N−, an olefin oligomer N and an olefin oligomer N +. A first distillation step that separates into min
A second distillation step of separating a fourth fraction (bottom) mainly composed of olefin oligomer N + from the second fraction (bottom) to obtain a third fraction;
A third distillation step in which a fifth fraction mainly composed of the low molecular weight component N- is separated from the third fraction and the olefin oligomer N is recovered in a sixth fraction (bottom portion); A process for producing an olefin oligomer.
2. The method for producing an olefin oligomer according to 1, wherein the fifth fraction is refluxed to the polymerization solution.
3. The method for producing an olefin oligomer according to 1 or 2, wherein the olefin is an α-olefin.
4). 4. The method for producing an olefin oligomer according to 3, wherein the α-olefin is selected from 1-octene, 1-decene and 1-dodecene.
5. The method for producing an olefin oligomer according to any one of 1 to 4, wherein a distillation temperature in the third distillation step is lower than a distillation temperature in the second distillation step.
6). The method for producing an olefin oligomer according to any one of 1 to 5, wherein the olefin polymerization catalyst is a metallocene catalyst.
7). The olefin oligomer obtained by the manufacturing method of the olefin oligomer in any one of said 1-6.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the olefin oligomer from which the setting of distillation temperature becomes easier than the conventional method can be provided, reducing the light quantity mixed in a final product.

It is a schematic flowchart of the manufacturing apparatus of the olefin oligomer assumed by simulation.

  In the method for producing an olefin oligomer of the present invention, first, an olefin having 4 to 28 carbon atoms is polymerized in the presence of a catalyst, and polymerization is performed by mixing a plurality of olefin oligomers having different degrees of polymerization and an olefin that is an unreacted monomer. A liquid is produced. Next, an olefin oligomer having a predetermined polymerization degree is recovered from the polymerization solution as a product.

The olefin having 4 to 28 carbon atoms in the present invention is preferably an olefin having 4 to 20 carbon atoms. For example, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-heptene, Octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, etc. Is mentioned.
One or more of these are used. Of these, α-olefins are preferable, and α-olefins selected from 1-octene, 1-decene, and 1-dodecene are particularly preferable.

  As the polymerization catalyst that can be used, a metallocene catalyst, a Ziegler-Natta catalyst, or the like can be used, and a metallocene catalyst is preferable. For example, a metallocene catalyst that is a transition metal compound and a catalyst that contains at least one selected from a compound that can react with the transition metal compound or a derivative thereof to form an ionic complex or an aluminoxane can be given. An organoaluminum compound can be used as the promoter component.

  Examples of the metallocene catalyst include transition metal compounds represented by the following formula (I).

(In the formula, M represents a metal element of Groups 3 to 10 of the periodic table or a lanthanoid series, and E ¹ and E ² represent a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, and a heterocyclopentadienyl group, respectively. , A ligand selected from a substituted heterocyclopentadienyl group, an amide group, a phosphide group, a hydrocarbon group and a silicon-containing group, which forms a crosslinked structure via A ¹ and A ² They may be the same or different from each other, X represents a sigma-binding ligand, and when there are a plurality of X, the plurality of X may be the same or different, and other X, E ¹ , It may be cross-linked with E ² or Y.
Y represents a Lewis base, and when there are a plurality of Y, the plurality of Y may be the same or different, may be cross-linked with other Y, E ¹ , E ² or X, and A ¹ and A ² are A divalent bridging group that binds two ligands, a hydrocarbon group having 1 to 20 carbon atoms, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, a germanium-containing group, a tin-containing group , -O -, - CO -, - S -, - SO 2 -, - Se -, - NR 1 -, - PR 1 -, - P (O) R 1 -, - BR 1 - or -AlR ¹ - R ¹ represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms or a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, which may be the same as or different from each other. q represents an integer of 1 to 5 and represents [(M valence) -2], and r represents an integer of 0 to 3. )

In the above formula (I), M represents a metal element of Groups 3 to 10 of the periodic table or a lanthanoid series, and specific examples include titanium, zirconium, hafnium, yttrium, vanadium, chromium, manganese, nickel, cobalt, palladium and Examples of these include lanthanoid metals, among which titanium, zirconium and hafnium are preferred from the viewpoint of olefin copolymerization activity.
E ¹ and E ² are preferably a substituted or unsubstituted cyclopentadienyl group or a substituted or unsubstituted indenyl group.

Specific examples of X include a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, an amide group having 1 to 20 carbon atoms, and a carbon number. Examples thereof include a silicon-containing group having 1 to 20, a phosphide group having 1 to 20 carbon atoms, a sulfide group having 1 to 20 carbon atoms, and an acyl group having 1 to 20 carbon atoms.
Specific examples of the Lewis base of Y include amines, ethers, phosphines, thioethers and the like.

Next, A ¹ and A ² are divalent bridging groups for bonding two ligands, which are a hydrocarbon group having 1 to 20 carbon atoms, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, and a silicon-containing group. Group, germanium-containing group, tin-containing group, —O—, —CO—, —S—, —SO ₂ —, —Se—, —NR ¹ —, —PR ¹ —, —P (O) R ¹ —, —BR ¹ — or —AlR ¹ —, wherein R ¹ represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, May be different.

Examples of the metallocene catalyst include transition metal compounds represented by the following formula (II).
E ^{1 ′} E ^{2 ′} MX _q Y _r (II)
(In the formula, M, X, q, Y and r are the same as those in the formula (I). E ^{1 ′} and E ^{2 ′} are E ¹ and E ² in the formula (I) and are not crosslinked. .)

A method and conditions for producing a polymerization solution of an olefin oligomer are known, and for example, JP-A-2009-149911 can be referred to.
An olefin oligomer having a predetermined polymerization degree is recovered as a product from the obtained polymerization solution.
The polymerization liquid is an olefin oligomer having a polymerization degree of N (hereinafter referred to as oligomer N), an unreacted olefin monomer, an oligomer having a polymerization degree lower than that of the oligomer N, and a liquid refluxed by a recycling process. A low molecular weight component (hereinafter referred to as component N-) containing at least one of the decomposition products contained in the olefin, and an olefin oligomer having a higher degree of polymerization than the oligomer N (hereinafter referred to as oligomer N +). It is a mixture.
When a metallocene catalyst is used, the generation of isomers can be suppressed, so that a product with few impurities can be obtained.

  In addition, the range of the polymerization degree of the olefin oligomer contained in a polymerization liquid is about 1-30 in the case of 1-decene, for example. In the present invention, an oligomer having a desired degree of polymerization can be recovered from the polymerization liquid which is such an oligomer mixture. In particular, it is suitable for recovering oligomers having a polymerization degree of 2 to 5.

  In the present invention, the oligomer N having a predetermined polymerization degree is recovered from the polymerization solution by three distillation steps. The recovered oligomer N may be composed only of the oligomer N, and may contain a low molecular weight component N− or an oligomer N + within the allowable range in terms of quality. Due to the nature of distillation, it usually contains a small amount of impurities.

In the present invention, the oligomer N is recovered by the following three distillation steps.
Distillation step 1:
The polymerization liquid is separated into a first fraction which is a part of the low molecular weight component N− and a second fraction (the bottom portion) consisting of the remainder of the low molecular weight component N−, the oligomer N and the oligomer N +. To do.
Distillation step 2:
The fourth fraction (canned portion) mainly composed of the olefin oligomer N + is separated from the second fraction (canned portion) to obtain a third fraction.
Distillation step 3:
From the third fraction, the fifth fraction mainly composed of the low molecular weight component N- is separated to recover the olefin oligomer N as the sixth fraction (bottom portion).

In the distillation step 1, the polymerization liquid is divided into a first fraction which is a part of the low molecular weight component N−, and a second fraction (the bottom portion) consisting of the remainder of the low molecular weight component, the oligomer N and the oligomer N +. And separated.
The distillation temperature for separating the first fraction and the second fraction (the bottom portion) is set in consideration of the pressure of the distillation column, the evaporation temperature of the oligomer N, the composition of each fraction, and the like.
The distillation temperature means a temperature at a predetermined position of the distillation facility. For example, when a distillation column is used, the temperature is at or near the distillation column bottom temperature, and when an evaporation tank is used, the temperature is the evaporation tank temperature.

The present invention is characterized in that it is not necessary to completely separate the low molecular weight component N- and the oligomer N or more in this step. That is, it can be distilled so that a small amount of low molecular weight component N- is mixed in the second fraction (the bottom).
As the weight ratio (M _N− / M _N ) of the low molecular weight component N− to the oligomer N in the second fraction (the bottom portion) approaches 0, the allowable range of the distillation temperature in this step becomes narrower. For example, when the oligomer N is a dimer of 1-decene, if the weight ratio (M _N− / M _N ) is set to 100 × 10 ⁻⁶ [weight / weight] or less in this step, the optimum distillation temperature is obtained. The allowable width is about 2 to 3 ° C. If the distillation temperature is lower than this range, the weight ratio of the low molecular weight component N- in the second fraction (bottom) exceeds 100 × 10 ⁻⁶ [weight / weight]. On the other hand, when the distillation temperature slightly exceeds the optimum temperature, the oligomer N evaporates and the amount of the oligomer N in the second fraction (bottom) is reduced. In such a narrow temperature range, it is difficult to operate the distillation apparatus while keeping the distillation temperature constant.

On the other hand, the present invention has a distillation step 3 for re-separating the low molecular weight component N- from the oligomer N, as will be described later. Therefore, in the distillation step 1, a small amount of the low molecular weight component N- may be mixed in the second fraction (bottom portion). As a result, the allowable range of the distillation temperature can be set widely as required.
For example, by setting the weight ratio (M _N− / M _N ) of the low molecular weight component N− to the oligomer N in the second fraction (the bottom portion) to be about 1% (0.01 [weight / weight]). The set value of the distillation temperature can be set to 20-30 ° C. lower than the optimum condition. Furthermore, by setting (M _N− / M _N ) to about 2%, the set value of the distillation temperature can be set to 70 to 80 ° C. lower than the optimum condition.

As described above, the permissible range of the distillation temperature becomes extremely wide only by leaving a small amount of the low molecular weight component N- in the second fraction (the bottom portion). Therefore, it becomes easy to operate the distillation apparatus at a constant temperature.
The amount of the low molecular weight component N- remaining in the second fraction (the bottom portion) is not particularly limited and can be appropriately adjusted within a range that does not adversely affect the distillation steps 2 and 3 described later. Usually, it is preferable to set (M _N− / M _N ) to 1% or less. In the present invention, since the distillation temperature can be set lower than the optimum condition, almost all of the oligomer N is removed from the second fraction (can )

In the distillation step 2, a fourth fraction (bottom portion) mainly composed of the olefin oligomer N + is separated from the second fraction (bottom portion) to obtain a third fraction.
In this step, it is not necessary to completely separate the oligomer N and the oligomer N +. Specifically, distillation may be performed so that a small amount of oligomer N + is mixed in the third fraction, and distillation may be performed so that a small amount of oligomer N is mixed in the fourth fraction (bottom). May be.

In the former case, the third fraction is composed of a low molecular weight component N−, an olefin oligomer N and a small amount of oligomer N +, and the fourth fraction (bottom portion) is composed of oligomer N +. In this way, almost all of the oligomer N can remain in the third fraction. The amount of oligomer N + remaining in the third fraction may be appropriately set in consideration of the required quality of the final product.
On the other hand, in the latter case, the third fraction is composed of a low molecular weight component N− and an olefin oligomer N, and the fourth fraction (the bottom portion) is composed of a small amount of oligomer N and oligomer N +. In this way, the oligomer N + contained in the final product can be substantially eliminated, and the purity of the final product can be improved.
The distillation temperature for separating the fourth fraction (the bottom portion) and the third fraction is set in consideration of the pressure of the distillation column, the evaporation temperature of the oligomer N, and the like.

  In addition, since the component having a high polymerization degree of N + is distilled, the distillation temperature tends to be the highest among the three distillation steps. When this temperature exceeds 260 ° C., thermal decomposition becomes remarkable and light components are generated. Since almost all of them are mixed in the third fraction at the top of the column, and the product contains these light components, it becomes a quality problem, so pressure and temperature setting becomes very difficult. However, since there is the distillation step 3, the temperature and pressure can be easily set even if thermal decomposition occurs.

In the distillation step 3, the fifth fraction mainly composed of the low molecular weight component N- is separated from the third fraction, and the target oligomer N is recovered as the sixth fraction (bottom portion). . A small amount of oligomer N may be mixed in the fifth fraction.
The main component of the third fraction to be treated in this step is oligomer N due to the two distillation steps. Therefore, since the composition ratio of the processing object does not vary greatly, the variation of the optimum value of the distillation temperature is small. Therefore, it is easy to distill at a temperature optimal for the separation of the low molecular weight component N- and the oligomer N. Thus, the final product is recovered by evaporating the fifth fraction.

The distillation step 3 may be performed in a distillation column or in an evaporation tank.
The distillation temperature in the distillation step 3 is preferably lower than the distillation temperature in the distillation step 2. If the distillation temperature in the distillation step 3 is high, a part of the oligomer may be newly thermally decomposed and light components may be generated.

  In the production method of the present invention, the first fraction described above may be used as a raw material for polymerization. For example, unreacted olefin or oligomer with a low degree of polymerization contained in the first fraction may be refluxed in the polymerization step.

  Moreover, in the manufacturing method of this invention, you may re-inject into the distillation process 1 the 5th fraction mentioned above. For example, the fifth fraction may be mixed with the polymerization solution before distillation and charged into the distillation step 1. Thereby, the oligomer N contained in the fifth fraction can be recovered.

Hereinafter, an example in which the effect of the present invention is evaluated by simulation will be described.
First, as a comparative example, an example in which two distillation columns are used and the distillation temperature is fixed will be described. In this example, C20 which is a dimer is recovered as a product from a polymerization solution obtained by polymerizing 1-decene. As the composition of the polymerization solution, three types shown in Table 1 were assumed.
In Table 1, C10 is 1-decene, C20 is a 1-decene dimer, C30 is a 1-decene trimer, C40 is a 1-decene tetramer, and C50 + is 1-decene. It means a component of decene pentamer or higher.

[Simulation conditions]
-Calculation conditions It is set as 2 upper theoretical plate numbers excluding the condenser and reboiler of the 1st distillation column, 2 lower theoretical plate numbers, and 1.0 reflux ratio.
The second distillation column also has the same upper theoretical plate number, two lower theoretical plates, and a reflux ratio of 1.0.
Both the first distillation column and the second distillation column were distillation columns with baffles at the bottom. In the structure, the liquid pool temperature on the reboiler side is the inlet stage temperature, and the residue liquid extraction side is the tower bottom temperature.
The column top operating pressure is 4.0 kPa-A for the first distillation column and 0.1 kPa-A for the second distillation column.
As a product condition, the first distillation column is simulated by setting the content of C10 contained in C20 in the product to 10 ppm by weight or less.
Table 2 shows the simulation results of the optimum temperature of the distillation column.

In general operation of a distillation column, the temperature at a position where the temperature change is small is often captured and controlled, but the lowest temperature change is the lower fourth stage theoretical plate. If this temperature can be operated at a constant temperature with respect to changes in the raw material composition, the operation is easy. However, if operation at a constant temperature is not possible, it is necessary to change the control temperature based on the analysis value obtained by gas chromatography attached to the distillation column. The target analytical value is the analytical value of C10 and C20 at the bottom of the first distillation column, and the accuracy of analyzing the calculated value of C10 / C20 with an accuracy of 10 × 10 ⁻⁶ [weight / weight] is required. is there. However, the analysis accuracy in gas chromatography is generally about 0.01% by weight, and if it is more than that, special instrument performance management is required, and it is necessary to frequently exchange the column and check the calibration curve. . Therefore, in practice, it is difficult to operate the set temperature of the control stage of the distillation column from the analysis result by gas chromatography.
From Table 2, the control stage temperature with the smallest temperature change with respect to the feed composition was calculated as constant.

・ Simulation of operating conditions at a constant temperature C10 contained in C20 in the product is 10 × 10 ⁻⁶ [weight / weight] or less, the first distillation column was obtained from the simulation, and the temperature control stage is the lower fourth stage theory As a stage, the simulation is performed at an average temperature of 227 ° C. from 225 ° C., 227 ° C., and 229 ° C. of the optimum temperature for each raw material composition.
What is calculated by calculation is the component ratio of C10 and C20 at the bottom of the first distillation column and the amount of C20 lost to the top of the column. The loss amount of C20 is evaluated based on the loss ratio in the supplied C20 because the C20 concentration in the raw material is different.
Table 3 shows the component ratio of C10 and C20 at the bottom of the first distillation column and the amount of C20 lost to the top when the control temperature is constant.

In the case of a light raw material (polymerization liquid 1), if the temperature of the control stage is constant, the temperature becomes higher than the optimum value, and the loss rate of C20 contained in the first fraction is very large. Tend to be. Since the loss rate of C20 is as large as several percent, operation at a constant temperature cannot be performed.
Further, in the case of the heavy raw material (polymerization liquid 3), if the temperature of the control stage is constant, the temperature becomes lower than the optimum value, and C10 is the bottom bottom liquid (second fraction). Will be included in many. If the target concentration is several tens × 10 ⁻⁶ [weight / weight] or less, there is no problem. However, when the target concentration is further deviated from the optimum set temperature, the C10 concentration increases in proportion to the C10 standard in the product C20. If the value is strict, problems will arise.

  Thus, when the composition of the polymerization solution is different, the optimum value of the distillation temperature varies. It can be seen that when the distillation temperature slightly deviates from the optimum value, the amount of C20 recovered or the amount of light components changes greatly. In this example, since the system uses two distillation columns, there is no step of separating light components mixed in the product after the first distillation column.

Subsequently, in order to solve the problem of the comparative example, a simulation is performed in a case where a third evaporation tank is installed.
In this simulation, C20, which is a dimer, is recovered as a product from a polymerization solution obtained by polymerizing 1-decene in a configuration system using three distillation towers and three evaporation tanks. The composition of the polymerization solution is the same as the above example. Table 4 shows the supply rate of each component.

FIG. 1 shows a schematic flow diagram of the olefin oligomer production apparatus assumed in the simulation. This manufacturing apparatus is a three-column configuration system in which three distillation columns or evaporation tanks are connected.
The first distillation column 10 uses a polymerization liquid obtained by a polymerization step (not shown) as a first fraction that is a part of the low molecular weight component (C10), the remainder of C10, and an oligomer of C20 or higher (C20 + And a second fraction (canned portion).
In the second distillation column 20, the second fraction (the bottom portion) is divided into the fourth fraction (the bottom portion) composed of the remainder of C30 + and a part of oligomers (C30 +) of C10, C20 and C30 or higher. And a third fraction consisting of
The third evaporating tank 30 separates the third fraction into a fifth fraction consisting of a part of C10 and C20 and a sixth fraction consisting of the remainder of C20 and C30 + (the portion taken off). To do.
As a product, the sixth fraction (the bottom) is recovered, the fifth fraction is refluxed to the first distillation column, and C20 is recovered.

-Simulation of operating condition with constant control temperature For the polymerization liquids 1 to 3, the temperature control of the first distillation column is controlled at 230 ° C at the reboiler inlet. This temperature is 1 ° C. lower than the lowest temperature of the corresponding stage in Table 2 (231 ° C. of polymerization liquid 1).
The temperature control of the second distillation column is constant at 248 ° C. at the reboiler inlet.
The operating condition of the third evaporation tank was heated to 190 ° C. at the inlet of the evaporation tank, and the operating pressure of the third evaporation tank was 1 kPa-A. In this operation, about 5% of evaporation occurs due to evaporation, and the liquid drops to about 185 ° C. due to latent heat of evaporation.
The simulation was performed at a raw material flow rate of 1000 kg / hr.
Table 5 shows the composition of the second fraction obtained by fractionation in the first distillation column (table fraction), Table 6 shows the fractionation result in the second distillation column, and Table 7 shows fractionation in the third evaporation tank. The results are shown in Table 7.

  In the fractionation by the first distillation column, since the set temperature is slightly lower than the optimum temperature, a part of C10 remains in the second fraction (the bottom portion), but all of C20 is the second fraction. It exists in (canned portion). Since the difference between the optimum temperature of the polymerization liquids 2 and 3 and the set temperature is larger than that of the polymerization liquid 1, the residual amount of the C10 component is increased.

The properties and yield of the final product (C20) (description is loss rate) can be grasped from Table 7. In the present invention, in any of the polymerization solutions 1 to 3, the concentration of C10 in the final product can be reduced to 100 × 10 ⁻⁶ [weight / weight] or less without changing the control temperature. Further, the loss rate of C20 in the distillation system can be suppressed to 0.1% or less.
Thus, in the present invention, a high-quality olefin oligomer can be efficiently produced without setting the distillation temperature to an optimum value in accordance with the composition.

By the production method of the present invention, a high-quality olefin oligomer can be produced efficiently.
The olefin oligomer obtained by the production method of the present invention can be used as a lubricating oil base material.

10 1st distillation column 20 2nd distillation column 30 3rd evaporation tank

Claims (7)

An olefin oligomer N having a polymerization degree of N (N is 2 or more) by polymerizing an olefin having 4 to 28 carbon atoms, a component N- having a lower molecular weight than the olefin oligomer N, and the olefin oligomer Producing a polymerization liquid containing an olefin oligomer N + having a higher degree of polymerization than N;
A method for producing an olefin oligomer, comprising a step of recovering the olefin oligomer N from the polymerization solution,
In the recovery step, the polymerization liquid is divided into a first fraction which is a part of the low molecular weight component N−, a second fraction comprising the remainder of the low molecular weight component N−, an olefin oligomer N and an olefin oligomer N +. A first distillation step that separates into min
A second distillation step of separating a fourth fraction (bottom) mainly composed of olefin oligomer N + from the second fraction (bottom) to obtain a third fraction;
A third distillation step in which a fifth fraction mainly composed of the low molecular weight component N- is separated from the third fraction and the olefin oligomer N is recovered in a sixth fraction (bottom portion); A process for producing an olefin oligomer.   The method for producing an olefin oligomer according to claim 1, wherein the fifth fraction is refluxed to the polymerization solution.   The method for producing an olefin oligomer according to claim 1 or 2, wherein the olefin is an α-olefin.   The method for producing an olefin oligomer according to claim 3, wherein the α-olefin is selected from 1-octene, 1-decene and 1-dodecene.   The method for producing an olefin oligomer according to any one of claims 1 to 4, wherein a distillation temperature in the third distillation step is lower than a distillation temperature in the second distillation step.   The method for producing an olefin oligomer according to any one of claims 1 to 5, wherein the olefin polymerization catalyst is a metallocene catalyst.   The olefin oligomer obtained by the manufacturing method of the olefin oligomer in any one of Claims 1-6.

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