JP3086521B2 - Olefin oligomer separation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for separating olefin oligomers.

[0002]

2. Description of the Related Art Oligomers of α-olefins having 8 to 12 carbon atoms are mainly produced as raw oils for synthetic lubricating oils such as engine oils. Among these α-olefin oligomers, α-olefin oligomers containing trimers as a main component, especially synthetic lubricating oils containing a trimer of 1-decene as a main component, have low viscosity and are used as raw material oils for high-performance engine oils. As it is extremely useful, its demand is increasing. Conventionally, the following methods have been known as methods for producing an α-olefin oligomer containing a trimer as a main component.

The type and reaction conditions of the catalyst used in the α-olefin oligomerization reaction are adjusted to produce an α-olefin oligomer having a low content of tetramer or higher oligomer, and from this α-olefin oligomer, A method for obtaining an α-olefin oligomer containing a trimer as a main component by performing a hydrogenation treatment after separating a low-boiling component containing an isomer.

An oligomer other than a trimer such as a tetramer and an α-olefin oligomer containing a trimer are subjected to a hydrogenation treatment, followed by distillation to obtain an α-olefin oligomer having a trimer as a main component. How to get (US Patent 4,
950,822).

After removing low-boiling components in the reaction product obtained by the oligomerization reaction of α-olefin by distillation (topping), vacuum distillation is performed at a reduced pressure of, for example, 0.6 Torr, followed by hydrogenation treatment. To obtain an intermediate boiling component having a trimer as a main component (US Pat.
4,950,822).

Among the above-mentioned methods, the above-mentioned method has a disadvantage that the yield of the oligomer reaction is low, and if the yield is to be improved, the content of the α-olefin oligomer of at least tetramer increases. was there. Further, in the above method, in the distillation separation of the trimer and the oligomer of the tetramer or more, the lightening by the thermal decomposition of the olefin oligomer proceeds, and the bromine value of the α-olefin oligomer containing the trimer as a main component is reduced. There was a drawback that it became big. U.S. Pat. No. 4,950,822 describes that even when vacuum distillation is carried out at a reduced pressure of 1.4 Torr, for example, the bromine number of the intermediate boiling point component containing a trimer as a main component increases. Therefore, it was considered that it was extremely difficult to obtain an intermediate boiling component without increasing the bromine value by ordinary distillation. Here, the bromine value can serve as an index indicating the ratio of the lightened components. When the ratio of the lightened components increases, the performance as a synthetic lubricating oil decreases. In contrast, the above method is disclosed in U.S. Pat.
No. 4,950,822 discloses that the above-mentioned disadvantages of the method are solved.

[0007]

However, in the above-mentioned method, vacuum distillation is performed at a relatively high degree of reduced pressure as described above, so that the equipment cost of the distillation apparatus increases and the operation becomes complicated. And so on. The other method has a drawback that in order to effectively use oligomers of tetramers or more separated by vacuum distillation, they must be separately hydrogenated.

[0008] Accordingly, an object of the present invention is to remove a middle-boiling component containing a trimer as a main component from a reaction product obtained by an oligomerization reaction while suppressing an increase in bromine value under relatively mild conditions. It is an object of the present invention to provide a method for separating an olefin oligomer, which can be separated by the above method.

[0009]

According to the present invention, there is provided a method for separating an olefin oligomer having at least 6 carbon atoms.
From the reaction product obtained by the oligomerization reaction of olefin No. 18, a low boiling component containing a dimer, an intermediate boiling component containing a trimer as a main component, and a high boiling point containing a tetramer or more oligomer component When separating the components, the oligomer composition containing at least the intermediate boiling component and the high boiling component is subjected to a hydrogenation treatment, and then the temperature at the bottom of the column is set to 290
It is characterized by including a step of performing steam distillation at a temperature of not more than ° C.

Hereinafter, the present invention will be described in detail. In the method of the present invention, a reaction product obtained by oligomerization of an olefin having 6 to 18 carbon atoms is used as a starting material. The olefin oligomerization is performed as follows. That is, the olefin used for the oligomerization may be an α-olefin or an internal olefin as long as the olefin has 6 to 18 carbon atoms.
Α-olefins having 2 carbon atoms, especially α-olefins having 10 carbon atoms (1-decene) are preferred. The conditions for the oligomerization reaction are not particularly limited. For example, the oligomerization reaction can be carried out in the presence of boron trifluoride and its cocatalyst at a temperature of -20 to 90C, preferably -10 to 60C. Here, "in the presence of boron trifluoride and its co-catalyst" means, more specifically, boron trifluoride obtained from boron trifluoride and its co-catalyst together with boron trifluoride.
It means that a promoter complex is present. As the co-catalyst, an arbitrary compound which forms a complex having polymerization activity with boron trifluoride and a mixture thereof are used. Specifically, water, alcohol (methanol, ethanol, n
-Butanol, n-decanol, etc.), carboxylic acids (acetic acid, propionic acid, butyric acid, etc.), ethers (dimethyl ether, diethyl ether, etc.), acid anhydrides (acetic anhydride, succinic anhydride, etc.), esters (ethyl acetate, propionic acid, etc.) Methyl, etc.), ketones (acetone, methyl ethyl ketone, etc.), aldehydes (acetaldehyde, benzaldehyde, etc.) and the like. A particularly preferred example of the boron trifluoride / cocatalyst complex is a complex in which the molar ratio of boron trifluoride to n-butanol is 1: 1. The amount of the complex is not particularly limited, but is usually 0.05 to 10% by weight, preferably 0.1 to 5% by weight based on the olefin.
It is. A solvent is not particularly necessary for carrying out the oligomerization reaction, but if desired, halogenated hydrocarbons (carbon tetrachloride, chloroform, methylene chloride, etc.), chain saturated hydrocarbons (pentane, hexane, heptane, etc.), alicyclic hydrocarbons Hydrogen (cyclohexane, methylcyclohexane, decalin, or the like) or the like can be used.

[0011] The method of the present invention comprises the steps of: removing a low-boiling component containing a dimer from a reaction product obtained by an oligomerization reaction;
When separating an intermediate boiling component containing a trimer as a main component and a high boiling component containing a tetramer or more oligomer component,
First, a hydrogenation treatment is performed on an oligomer composition containing at least an intermediate boiling component and a high boiling component. Here, the “oligomer composition containing at least an intermediate boiling component and a high boiling component” means (A): a low boiling component including a dimer obtained by an oligomerization reaction, and a trimer as a main component. (B): oligomer reaction product (A) containing an intermediate boiling component and a high boiling component containing a tetramer or higher oligomer, and the oligomer reaction product (A) is treated by a method such as distillation (topping) to reduce the low boiling component. It means an oligomer composition containing an intermediate boiling component and a high boiling component obtained by removal. That is, the oligomer composition subjected to the hydrogenation treatment in the method of the present invention is obtained by removing the oligomer reaction product (A) itself or the oligomer composition (B) obtained by removing the low boiling component from the oligomer reaction product (A). In any case, the former oligomer reaction product (A) may be subjected to a hydrogenation treatment. After a series of steps of hydrogenation and steam distillation as described later, a fraction containing a low-boiling component and a middle-boiling component is obtained. It is necessary to remove low boiling components from the fraction by means such as distillation.

The hydrogenation treatment in the method of the present invention can be performed by a conventional method. For example, the temperature, pressure, catalyst, and hydrogen amount of hydrogenation are as shown below.

Temperature: usually 50 to 270 ° C., preferably 100 to 240 ° C.
Although the temperature is not particularly limited, it can be arbitrarily selected in consideration of the reaction rate.・ Pressure Usually, normal pressure to 30 kg / cm ² G, 10 to 20 k
g / cm ² G is preferred, but not particularly limited. -Catalyst A palladium-based catalyst is preferable, although it is not particularly limited as long as it is a hydrogenation catalyst. There is no particular limitation on the carrier and the amount of palladium carried when using a palladium-based catalyst. The use conditions are preferably ¹ to 0.5 hr ^-1 (WHSV). -Hydrogen amount Any amount is sufficient as long as the olefin oligomer is substantially hydrogenated.

By this hydrogenation treatment, the unsaturated double bond in the olefin oligomer is hydrogenated, and the bromine value of the oligomer composition is reduced.

In the method of the present invention, steam distillation is performed after the above-mentioned hydrogenation treatment. In this steam distillation, the temperature at the bottom of the distillation column is limited to 290 ° C. or lower in order to suppress lightening due to thermal decomposition of the olefin oligomer. Particularly, the bottom temperature is 230 to 290 ° C., and the bottom pressure is 10 to 40 Torr.
In this case, steam distillation can be effectively performed without causing lightening due to thermal decomposition of the oligomer. Therefore, the bottom temperature and pressure are 230-290 ° C, 10-
40 Torr is preferred.

Other preferable conditions in the steam distillation are shown below together with the column bottom temperature and pressure.・ Top temperature, pressure: 90 to 150 ° C., 5 to 35 Torr ・ Bottom temperature, pressure: 230 to 290 ° C., 10 to 40 Torr ・ Reflux ratio (R / D): 0.1 to 1 ・ Water supply stage: Column bottom ・ Amount of water supplied: An amount corresponding to 3 to 40% by weight of the amount of the oligomer composition supplied to the distillation column ・ Column bottom residence time: 120 minutes or less The column bottom residence time is distillation. It means the value obtained by dividing the liquid weight of the bottom liquid of the column by the amount of high-boiling components withdrawn per unit time. -Others: It is preferable that the water distilled from the top of the tower is not condensed in the receiving tank, but is discharged as steam from the top of the distillation tower to the outside of the system.

By this steam distillation, a fraction containing a middle boiling component is distilled off from the top of the column, a fraction containing a high boiling component is removed from the bottom of the column, and the middle boiling component is separated from the high boiling component.

In this steam distillation, a reduced pressure (10 to 40 Torr at the bottom pressure and 5 to 35 Torr at the top pressure) which is gentler than the reduced pressure (for example, 0.6 Torr) at the time of distillation in the above-mentioned prior art method may be used. Thereby, advantages such as reduction of the equipment cost of the distillation apparatus and easiness of operation can be obtained as compared with the method of the prior art. In addition, according to the steam distillation of the present invention, the bottom temperature can be suppressed to 290 ° C. or lower even at a moderate degree of pressure reduction, so that the intermediate boiling point component reduced by the hydrogenation treatment does not occur due to lightening due to thermal decomposition of the oligomer. A desired intermediate boiling point component can be obtained without increasing the bromine number of the compound.

As described above, in the method of the present invention, when the above oligomer reaction product (A) is used as a starting material before hydrogenation, it is distilled from the top by steam distillation. Since the fraction containing the middle boiling point component also contains the low boiling point component, in order to separate them, the above fraction is subjected to ordinary distillation treatment, the low boiling component is distilled off from the top of the column, and It is necessary to remove the intermediate boiling component from the wastewater. The distillation conditions at this time are appropriately selected so that the low-boiling component and the high-boiling component are separated by distillation.

The thus obtained intermediate boiling point component containing a trimer as a main component is preferably used for applications such as synthetic lubricating oils.

[0021]

Embodiments of the present invention will be described below. Example 1 (1) Oligomer Reaction Product The oligomer reaction product used as a starting material in the olefin oligomer separation method of the present invention was boron trifluoride and boron trifluoride / n-butanol complex (molar ratio = 1: 1). An oligomer reaction product obtained by polymerizing 1-decene at 20 ° C. in the presence of 1). This 1-
The composition of the decene oligomer reaction product is as shown in Table 1.

[0022]

[Table 1]

(2) Removal of low-boiling components The 1-decene oligomer reaction product having the above composition is subjected to distillation (topping) at a temperature of 280 ° C. and a reduced pressure of 5 Torr to obtain a monomer and a dimer. Was removed. The oligomer composition after the removal of the low-boiling components had the composition shown in Table 2.

[0024]

[Table 2]

(3) Hydrogenation treatment Next, the oligomer composition was supplied to the hydrogenation reactor (fixed bed reactor) from the bottom of the reactor, and subjected to hydrogenation treatment under the following conditions. Amount of supply of oligomer composition: 5 kg / hr Reactor inlet temperature: 150 ° C. Pressure: 10 kg / cm ² G Catalyst: Palladium catalyst (palladium carrying amount: 0.55
% By weight, carrier: alumina) 10 kg Hydrogen supply amount: 1010 Nl / hr Bromine value (BV ₁ ) of oligomer composition after hydrogenation treatment
Was 0.49. The bromine value is determined according to JIS K260.
5 was measured.

(4) Steam distillation A distillation column having 6 tray stages was used, and 3 mm from the top of the distillation column.
Place the oligomer composition after hydrogenation treatment on the first tray
0 kg / hr, and 1.0 k of water from the bottom of the tower
g / hr, the bottom pressure was 30 Torr, the bottom temperature was 290 ° C., the top pressure was 25 Torr, and the top temperature was 15 Torr.
The temperature was adjusted to 0 ° C., and steam distillation was performed.

By this steam distillation, an intermediate boiling point component containing 98% by weight of a trimer of 1-decene was distilled off together with water from the top of the column. This water was discharged outside the distillation column at 1.0 kg / hr without condensation. On the other hand, the intermediate boiling components are condensed and received in the overhead liquid receiving tank, a part of which is recycled as a reflux liquid (reflux ratio: 0.2), and the remainder is discharged out of the distillation column at a rate of 3.0 kg / hr and separated. did. 7.0 kg from the bottom of the tower
/ Hr of high boiling point components.

The bromine number (BV ₂ ) of the intermediate boiling point component thus separated was measured by the same method as described above, and based on the measured value (BV ₂ ), the bromine number (BV ₁ ) of the oligomer composition before steam distillation was determined. ) To increase the bromine number (△ B
V) was determined. As a result, the increase in bromine value (△ BV)
Was 0.2 when the bottom liquid retention time was 10 minutes, and 0.2 when it was 30 minutes, indicating that the bromine value hardly increased.

Example 2 and Example 3 The procedure of Example 1 was repeated except that the bottom pressure and the bottom temperature were adjusted to the conditions shown in Table 3, and the top pressure and the top temperature were adjusted accordingly. Thus, an intermediate boiling point component having a trimer of 1-decene as a main component was separated. The increase in bromine value (ΔBV) of each intermediate boiling point component thus separated was determined in the same manner as in Example 1. Table 3 shows the results. As shown in Table 3, the increase in the bromine value was 0.1 even when the residence time in the bottom liquid was 120 minutes, and almost no increase in the bromine value was observed.

Comparative Example 1 The oligomer composition subjected to the hydrogenation treatment in the same manner as in Example 1 was distilled without supplying water to the distillation column.
An intermediate boiling point component mainly composed of 1-decene trimer was distilled off from the top of the column. At the time of distillation, as shown in Table 3, the column bottom pressure was set to 10 Torr as in Example 3, but the column bottom temperature was as high as 310 ° C. The amount of increase in bromine value (臭 BV) of the intermediate boiling point component thus separated was determined in the same manner as in Example 1. As a result, the amount of increase in the bromine value was 0.4 when the residence time in the bottom liquid was 10 minutes, and 0.6 when the residence time in the column was 30 minutes.

[0031]

[Table 3]

From the above, in the first to third embodiments,
It can be seen that the increase in the bromine value of the intermediate boiling point component containing a trimer as a main component is suppressed.

[0033]

As described above, according to the present invention,
Intermediate boiling components mainly composed of trimers generated by the oligomerization reaction can be separated under relatively mild conditions while suppressing an increase in bromine value (lightening).

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-49-85243 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 7/05-7/06 C07C 7 / 163 C07C 11/02 C10M 107/10 CA (STN)

Claims (1)

(57) [Claims] 1. A reaction product obtained by an oligomerization reaction of an olefin having 6 to 18 carbon atoms, a low boiling component containing a dimer, an intermediate boiling component containing a trimer as a main component, and 4 When separating a high-boiling component containing an oligomer component or more, a hydrogenation treatment is applied to the oligomer composition containing at least the intermediate-boiling component and the high-boiling component, and then the temperature at the bottom of the column is set to 290 ° C. or lower. A method for separating olefin oligomers, comprising a step of performing steam distillation.