JPH0733781A - Method for purifying triisobutylaluminum - Google Patents

Abstract

PURPOSE:To provide a method for purifying triisobutylaluminum capable of readily carrying out distillation and supplying a high distillation yield by converting a diisobutylaluminum halide into triisobutylaluminum during synthesis, reducing the amount of the diisobutylaluminum halide mixed with a liquid in a distillation still. CONSTITUTION:In a method for distilling and purifying crude triisobutylalttminum obtained from aluminum or an aluminum allay containing Ti or Zr, hydrogen, isobutylene and triisobutylaluminum, 0.02-0.2g/ml of isobutylene is left and the amount of a diisobutylaluminum halide is reduced. Isobutylene is separated and removed and triisobutylaluminum is distilled at 50-70 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for purifying triisobutylaluminum (hereinafter abbreviated as TIBA) which is useful as an olefin polymerization catalyst or an organic synthetic reagent.

[0002]

2. Description of the Related Art It is preferable to remove i-butylene and i-butane under vacuum heating before distillation of TIBA.
1, 674 (Dow Chemical). It is also possible to first separate the liquid reaction product of TIBA from the rest of the easily volatile components in a vacuum and then distill it in a distillation column.
(Karl Ziegrel). Also TIBA
It is described in the above-mentioned BP-801,674 that the distillation condition is preferably not higher than 70 ° C under vacuum and not higher than 65 ° C.

Crude TIBA that has left the reaction system and before purification includes diisobutylaluminum hydride (i-Bu ₂ AlH, DIBAH) in addition to unreacted isobutylene and by-product isobutane.
Abbreviated. ) Is mixed. This DIBAH has a higher boiling point than TIBA, and when it is mixed, it raises the temperature of the bottom liquid during the distillation of TIBA, which not only causes the decomposition of TIBA, but also

[Chemical 1] Decomposes to precipitate fine particles of metallic aluminum, which accelerates the decomposition, mixes with product TIBA due to entrainment and turns black, and the generated hydrogen is not collected by the cooling trap. Therefore, there is a problem in that the degree of vacuum is lowered.

[0004]

DISCLOSURE OF THE INVENTION The object of the present invention is to suppress the amount of DIBAH, which causes the above-mentioned various problems, mixed in the distillation bottom liquid, to obtain a high distillation yield and to facilitate distillation. To provide a way to do it.

[0005]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, the present invention is a method for distilling and refining crude triisobutylaluminum obtained from aluminum or aluminum alloy containing Ti or Zr in an amount of 0.01 to 1.0 wt%, hydrogen, isobutylene, and triisobutylaluminum, and isobutylene in an amount of 0.02 to 0.2 g / Diisobutylaluminum hydride is reduced by leaving it at a concentration of ml, and isobutylene is then separated and removed.
A method for purifying triisobutylaluminum, which comprises distilling at 50 ° C to 70 ° C.

The present invention will be described in detail below. TIBA is
It is produced by the reaction of aluminum, hydrogen, isobutylene and triisobutylaluminum. More preferably, it is produced by the reaction of an aluminum alloy containing 0.01 to 1.0 wt% of Ti or Zr with hydrogen, isobutylene and triisobutylaluminum. After reaction, the liquid is purified by distillation after separating unreacted aluminum.
Becomes

However, TIBA is very easily decomposed by heat to become DIBAH and isobutylene. Therefore, distillation at 70 ℃ or higher causes a decrease in vacuum due to the generation of a large amount of gas and TIB
Distillation operation becomes virtually impossible due to the decrease in the distillation recovery rate of A. In addition, pressure loss generally occurs in the distillation / purification device. Further, the number of stages of the distillation column can be lowered to raise the reflux ratio, but if the reflux ratio is raised too much, the residence time increases and the thermal decomposition becomes remarkable. Therefore, the distillation temperature is lowered, but if the distillation temperature is lowered too much, it is necessary to strengthen the cooling of the trap, and further, the vapor density becomes small, and thus the problem that the distillation rate becomes small occurs. Expensive and not economical. Therefore, the practical distillation temperature is preferably 50 ° C. (TIBA vapor pressure 1.0 mmHg) or higher, and vacuum distillation is carried out while maintaining a vacuum degree corresponding to this temperature in the distillation apparatus. However, as distillation technology advances and energy costs decrease, it is possible to distill at lower temperatures.

When the boiling point of the distillation still liquid is examined, DIBA
DIBAH / TIBA = 1. theoretically with a mixture of H and TIBA.
At 0 / 1.5 (molar ratio) (that is, DIBAH concentration 32 wt%), there is a +10 ° C boiling point rise, and the boiling point becomes 70 ° C, making distillation impossible. However, the crude TIB that is the actual can
In addition to TIBA, which is easy to decompose, and DIBAH, which decomposes to generate hydrogen, and active fine aluminum powder, which accelerates decomposition, exists in A, the gas generation is higher than expected.
It was found that when the DIBAH concentration was much lower than 32 wt%, for example, when the DIBAH concentration was 17 wt% or more, the vacuum pressure inside the distillation apparatus increased due to gas generation, and distillation control became difficult.

Then, the present inventors next determined the DIBAH concentration.
When we examined the method to make it less than 17 wt%, we added isobutylene to the mixed solution of crude TIBA, reacted it with DIBAH, and left isobutylene in the solution at a concentration of 0.02 g / ml or more, so that the DIBAH concentration It has been found that can be less than 17 wt%. When isobutylene was added to the mixed solution of DIBAH and TIBA and reacted, TIBA was formed and the reaction was completed in equilibrium, so a small amount of DIBAH and isobutylene remained.

This reaction proceeds even at room temperature, but it takes 1 to 2 weeks. Therefore, the temperature of the reaction actually carried out is preferably 60 to 100 ° C, and the reaction time is 30 minutes to 10 ° C.
It is about time, preferably 1 to 5 hours.

Even if too large amount of isobutylene is added,
The deaeration and recovery of residual isobutylene is expensive, but not very effective. That is, the practically usable isobutylene concentration is 0.2 g / ml or less. For example, if 0.1 g / ml of isobutylene remains, the AlH ₃ concentration will be 0.25 wt%.
Since the DIBAH concentration is reduced to 3.6 wt%, the TIBA yield during distillation is extremely high. Where AlH ₃ is D in coarse TIBA
The amount of IBAH is converted into AlH ₃ by the following formula.

[Chemical 2]

Crude TIBA with DIBAH concentration decreased by reaction
Then removes the residual isobutylene. The place of removal may be in a distillation can, but a separate device is preferable. If it is done in a distillation can, it is not preferable because mechanical seal oil mixed with fine aluminum powder or crude TIBA is entrained and contaminates the inside of the distillation column. The method for separating isobutylene by degassing may be a method by vacuum degassing, a method of blowing an inert gas such as N ₂ or a method of combining vacuum degassing and blowing of an inert gas. The temperature at which isobutylene is separated is usually room temperature to 60 ° C. or lower, and the treatment time must be 1 to several hours. If it is performed at a high temperature for a long time, TIBA returns to DIBAH again along with the removal of isobutylene, which is not preferable.

Add isobutylene and react to react with DIBAH
Of residual isobutylene after removal of crude T
IBA is purified by distillation. Then, in addition to DIBAH, fine activated aluminum powder and mechanical seal oil are removed to obtain purified TIBA. If mechanical seal oil and other impurities are small, it is sufficient to remove fine aluminum powder by filtering. In particular, when the amount of residual isobutylene is increased to greatly reduce DIBAH, it can be suitably applied.

In the present invention, Ti or Zr is preferably 0.0
It can be applied to a crude TIBA obtained by reacting an aluminum alloy containing 1 to 1.0 wt% with hydrogen and isobutylene in the presence of triisobutylaluminum. The crude TIBA thus obtained has a lower DIBAH concentration than the crude TIBA obtained by using conventional pure aluminum as a raw material, so that the present invention can be carried out by further simplified equipment. ,preferable.

A pressure autoclave is usually used as an apparatus for adding isobutylene to a mixed solution of crude TIBA and reacting it with DIBAH. Further, the distillation apparatus may be a simple distillation apparatus in which the entrainment of the can solution is prevented, but a multistage, reflux, continuous, or multi-column system may be used in combination if necessary. Further, the present invention can be carried out entirely in a batch system, a semi-batch system or a continuous system.

[0016]

The present invention will be described in more detail with reference to the following examples, but the embodiments of the present invention are not limited thereto.

Example 1 Crude TIBA solution containing 20 wt% DIBAH (1.43 wt% in terms of AlH ₃ ) by reacting an aluminum alloy containing 0.05 wt% Ti, hydrogen and isobutylene in the presence of triisobutylaluminum. Got 500 g of this solution was charged into a stainless steel autoclave having an internal volume of 1 liter, and isobutylene was charged while stirring at 60 ° C. From time to time, the TIBA solution was sampled and analyzed, and the AlH ₃ concentration was 0.3 wt% (DIBAH conversion
The supply of isobutylene was stopped when it reached 4.3 wt%. The concentration of isobutylene in the liquid after the reaction is 0.08 g / ml
Met. Next, the reaction solution was transferred to a stainless steel 1l autoclave equipped with a nitrogen gas blowing tube, a vacuum pump, and a cooling trap for collecting isobutylene, and nitrogen gas was blown into the autoclave while stirring, and the temperature was 40 ° C and the degree of vacuum was 70 mmHg.
In 3 hours, almost all isobutylene was separated and removed. Then, 100 g of this treatment liquid was placed in a stainless steel simple distillation device that prevented entrainment of droplets, and the temperature of the can liquid was 60 ° C and the pressure was 1.7.
Distillation was started at mmHg and stopped at 70 ° C. 85 g of clear, colorless and pure TIBA liquid was obtained. The distillation yield for TIBA in the bottom liquid during distillation was 85%, but the recovery rate for TIBA in the crude TIBA liquid obtained from the aluminum alloy was 89%, which was higher than that for simply distilling the crude TIBA liquid. One of the features of the present invention is that the yield is improved. Furthermore, the crude TIBA solution has an AlH ₃ concentration of 1.43 wt.
% And calculated from the molar fraction of TIBA and DIBAH and the vapor pressure, this crude TIBA liquid has a bottom liquid temperature of 65 ° C and distillation pressure.
It should have been possible to start the distillation at 1.7 mmHg, but even if it was heated to 70 ° C or higher, it did not distill at all and the decomposition of TIBA started and distillation was not possible.

Examples 2, 3, 4 and 5 Using the crude TIBA solution and apparatus used in Example 1, crude TIBA
By changing the amount of isobutylene added to the liquid and changing the residual isobutylene concentration, the DIBAH concentration (Al
H ₃ concentration was measured and converted) was changed. After isobutylene was separated and removed in the same manner as in Example 1, distillation was performed. The results are shown in Table 1.

Example 6 Using the crude TIBA liquid and the apparatus used in Example 1, a crude TIBA was prepared.
Change the amount of isobutylene added to the liquid to change the residual isobutylene concentration to 0.20 g / ml, and change the DIBAH concentration after the reaction.
It was set to 0.13 wt%. After isobutylene was separated and removed in the same manner as in Example 1, the temperature of the can liquid was 50 ° C., the pressure inside the can was 1.0 mmHg.
It was distilled at. As a result, the recovery rate of TIBA in the crude TIBA liquid obtained from the aluminum alloy was 92%.

[0020]

[Table 1]

Comparative Examples 1 and 2 Using the crude TIBA liquid and apparatus used in Example 1, crude TIBA
The amount of isobutylene added to the liquid was changed as shown in Table 1 and the residual isobutylene concentration was changed to change the DIBAH concentration after the reaction (AlH ₃ concentration was measured and converted).
After isobutylene was separated and removed in the same manner as in Example 1, distillation was performed. The results are shown in Table 1. In Comparative Example 1, the residual isobutylene concentration was low, and the distillation was started at a bottom liquid temperature of 65 ° C, but the amount of TIBA distilled up to 70 ° C was small.
Above ℃, decomposition started and distillation could not be continued, and the recovery rate was extremely low. In Comparative Example 2, since a large amount of residual isobutylene was separated and removed, a large amount of loss was caused by the entrainment of TIBA, which resulted in a low recovery rate. Furthermore, the recovery rate of isobutylene was low and the economic loss was large.

[0022]

As described above, according to the method of the present invention, isobutylene is added to the mixed solution of TIBA and DIBAH after the synthesis reaction to cause the reaction, and the residual isobutylene is maintained at a concentration of 0.02 to 0.2 g / ml to remove the residual isobutylene. By rapidly degassing and then performing distillation, the amount of DIBAH mixed in the distillation bottom liquid can be suppressed, distillation can be performed easily, and a high distillation yield can be obtained.

Front Page Continuation (72) Inventor Seijiro Koga 1-6 Takasago, Takaishi-shi, Osaka Mitsui Toatsu Chemical Co., Ltd.

Claims (3)

[Claims] 1. A method for purifying crude triisobutylaluminum by distillation, wherein isobutylene is added in an amount of 0.02 to 0.2.
A method for purifying triisobutylaluminum, which comprises diluting diisobutylaluminum hydride at a concentration of g / ml to reduce isobutylene, and then isobutylene is separated and distilled at 50 ° C to 70 ° C. 2. The crude triisobutylaluminum is Ti
The method for purifying triisobutylaluminum according to claim 1, which is a crude triisobutylaluminum obtained from an aluminum alloy containing 0.01 to 1.0 wt% Zr, hydrogen and isobutylene. 3. The reaction temperature of 60 to 100 ° C. and the reaction time of 1 to 5 hours are the conditions for reducing the amount of diisobutylaluminum hydride by allowing isobutylene to remain at a concentration of 0.02 to 0.2 g / ml. Of triisobutylaluminum in.