JPH0733780A - Production of triisobutylaluminum - Google Patents

Abstract

PURPOSE:To provide industrial and extremely advantageous production method capable of suppressing the formation of a diisobutylaluminum halide and preparation of isobutane as by-products and capable of greatly improving the synthetic yield of triisobutylaluminum. CONSTITUTION:In reaction of synthesizing triisobutylaluminum by a continuous method, at the end of the reaction, the concentration of remaining isobutylene is regulated to a range from 0.02g/ml to 0.08g/ml to suppress formation of diisobutylaluminum halide during the synthesis.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art The synthesis of TIBA from aluminum metal, hydrogen and isobutylene is described in JP-B-32-5710.
It is described in. It is also known that TIBA is in equilibrium with diisobutylaluminum hydride (hereinafter referred to as DIBAH) and isobutylene.

When synthesizing TIBA in a continuous manner, raw materials isobutylene, hydrogen, and metallic aluminum are supplied to the reaction tank at a constant rate, and the produced TIBA is discharged from the reaction tank at a constant rate. However, isobutane was by-produced during the synthesis of TIBA, and the amount of the by-product was 20% or more and varied greatly depending on the amount of aluminum and the activity. For this reason, the raw material isobutylene was wasted. Further, the production rate of TIBA also changed significantly due to the change in the activity of aluminum metal. Therefore, the amounts of isobutylene and hydrogen consumed in the reaction tank constantly change, and the quality of TIBA produced continuously is not always constant, which makes it difficult to obtain high quality. Therefore, in order to treat a large amount of by-produced DIBAH, it was necessary to carry out an additional isobutylene-forming reaction as described in JP-B-32-5710.

[0004]

That is, an object of the present invention is to provide a continuous production method of TIBA in which the amount of isobutane by-product is suppressed and TIBA can be obtained in a high yield.

[0005]

The present inventors have completed the present invention as a result of extensive studies to solve the above problems. That is, the present invention is to mix aluminum, hydrogen and isobutylene with triisobutylaluminum,
In the reaction for synthesizing triisobutylaluminum in a continuous manner, 0.02 g / ml of isobutylene in the reaction solution
To 0.08 g / ml, the present invention relates to a method for producing triisobutylaluminum, which comprises:

The present invention will be described in more detail below. The reaction of the present invention is represented by the following general formula (Formula 1).

[Chemical 1]

The reactor is usually an autoclave equipped with a stirrer, but a shaking autoclave may be used. This reactor has a supply port for continuously supplying isobutylene, hydrogen, and metallic aluminum, and a discharge port for taking out a fixed amount of the reaction liquid. This reaction must be carried out under an inert gas atmosphere to avoid the presence of water and oxygen.

The raw materials aluminum, hydrogen and isobutylene are mixed with triisobutylaluminum (TIBA) and subjected to continuous reaction. The triisobutylaluminum to be mixed may be a reaction solution or a product. And isobutylene supplied from the discharged solution,
A quantity of TIBA corresponding to hydrogen and metallic aluminum is separated and extracted as a product, and most of the remaining TIBA and unreacted metallic aluminum, isobutylene and hydrogen are returned to the original reactor. The by-produced isobutane is discharged little by little so as not to accumulate in the system.

The aluminum to be used may be commercially available high-purity aluminum, but in order to improve the reaction rate, T
An aluminum alloy containing 0.01 to 1.0 wt% of i or Zr is more preferable. In order to increase the reaction rate, the smaller the particle diameter of the alloy particles, the better. Atomized aluminum and aluminum flakes are preferably used. It is preferably activated in advance by a known method.

Isobutylene may be initially charged in an appropriate amount, and the rest may be continuously or intermittently supplied together with hydrogen as the reaction progresses. Hydrogen is charged at a constant pressure at the initial stage of the reaction, and then is continuously or intermittently supplied as the reaction progresses. Similarly, aluminum powder is charged at a constant pressure at the initial stage of the reaction, and then continuously or intermittently supplied as the reaction progresses. Then T
IBA is used to act as a catalyst for activating the aluminum powder by contacting and stirring the aluminum powder, and for keeping the aluminum powder in a slurry state. Therefore, it is preferable that the amount of TIBA for mixing the raw materials is as large as possible within an economically allowable range, and the TIBA circulated is mixed with the raw materials at a predetermined ratio and supplied to the continuous reactor. To be done.

This reaction is carried out in the temperature range of 100 to 200 ° C., but if the temperature is low, the reaction rate is slow, and if the temperature is high, the pressures of isobutylene and by-product isobutane are high.
The reaction temperature is preferably 120 to 140 ° C.

The hydrogen partial pressure is in the range of 1 to 250 kg / cm ² . However, if Ti or Zr is 0.01-1.
When an aluminum alloy containing 0 wt% is used, it is generally 1 to 12 kg / cm ² , preferably ² to 10 kg / c.
A m ^{2 value} is preferable because the by-product of isobutane is greatly reduced.

The reaction time, that is, the residence time of the reaction mass, is
It is determined according to the raw material ratio, the reaction temperature and the reaction pressure so that an appropriate conversion rate and selectivity can be obtained.

According to the method of the present invention, the concentration of isobutylene in the liquid phase portion in the reaction system is kept constant at 0.02 g / ml under standard conditions.
To 0.08 g / ml is characterized in that the reaction is allowed to proceed. Although the amount of dissolved isobutylene is the concentration in the liquid phase, it can be obtained by backcalculating from the corresponding partial pressure of the upper gas phase. In this way, to keep the isobutylene concentration in the liquid phase in the reaction system constant within the above range,
It is necessary for continuous production of TIBA in which the amount of by-product of isobutane is suppressed and TIBA is obtained in high yield. In the batch system in which the entire amount is discharged after the reaction is completed, the concentration of isobutylene in the middle does not pose a problem so long as it is maintained at the above-mentioned isobutylene concentration at the time of discharging after the reaction is completed.

The form of the continuous reaction of the present invention includes a semi-batch type as well as a completely continuous type. As the continuous reaction device, a tubular type, a tower type, a fluidized bed type, a moving bed type or the like can be used. In the case of the tubular type or the tower type, it is possible to use a baffle plate or a filling material inside. In the semi-batch type, a tank reactor equipped with a stirrer can be used. Further, the unreacted aluminum powder can be filtered by an internal filter so as not to be discharged to the outside, or when it is extracted to the outside, it is filtered without contacting with oxygen and then the system It can also be circulated in.

Crude TIB, a product that is continuously discharged.
In A, in addition to excess TIBA, residual aluminum powder, by-produced isobutane, the above isobutylene and DIBA
H is mixed. Therefore, the amount of crude TIBA commensurate with the supplied isobutylene, hydrogen, and metallic aluminum is separated from the raw material. Then, isobutane and isobutylene are separated by degassing or the like, and then filtered or distilled to remove aluminum powder to obtain TIBA as a product. However, a small amount of oil or DIBA leaking from the device
It is preferable to include a distillation step because H can be removed.
Here, the aluminum powder and DIBAH are returned to the reactor together with the crude TIBA, isobutylene is separated and recovered and reused, and isobutane is discarded. Alternatively, isobutane and isobutylene may be reused or discarded as a mixed gas.

If DIBAH remains in the refining process, the yield of TIBA as a product is lowered, so that D in crude TIBA is not used.
IBAH should be reduced as much as possible. According to the method of the present invention, when isobutylene in the reaction solution is reacted,
In the standard state, by adjusting the concentration in the range of 0.02 g / ml to 0.08 g / ml, the amount of DIBAH falls within a predetermined range, that is, AlH ₃ is 0.2 wt% to 0.7 wt%.
It can be kept in the range of%. Here, AlH ₃ is the amount of DIBAH in TIBA converted into AlH ₃ and displayed, and is defined by the following (formula 2).

[0018]

[Chemical 2]

Specifically, the presence of 1 wt% of AlH ₃ means the presence of 14.2 wt% of DIBAH. The presence of AlH ₃ from 0.7 wt% to 0.2 wt% means that DIBAH is from 10.0 wt% to 2.8 wt%.
Means to exist. In this case, a high yield can be expected in the purification process. Adjust the dissolved isobutylene amount to 0.
The amount of AlH ₃ is 0.2 wt% if it is set to 08 g / ml or more.
It can be further reduced to the following, but in this case, when obtaining the purified TIBA from the crude TIBA, the amount of isobutylene to be released or recovered becomes too large and the apparatus becomes complicated, which is not economical. Further, when the amount of isobutylene is 0.02 g / ml or less, AlH ₃ increases and the purification yield decreases, which is not preferable. Furthermore, TIBA is reduced by the amount of increase in DIBAH, which is also not preferable.

It has not been known at all in the past to suppress the purification of AlH ₃ by allowing isobutylene to be present at a constant concentration during the reaction as in the method of the present invention. For example, in the examples described in USP-2900402, it is described that 2.4 mol of TIBA is quantitatively produced from 7.2 mol of isobutylene. In the reaction system of this patent, as is clear from the examples, no by-product isobutane is produced, no DIBAH is produced, and no residual isobutylene is present. Therefore, TIBA ← → DIB
It can be seen that there is also no equilibrium relationship shown for AH + isobutylene. However, the present inventors have found that, in reality, a large amount of by-product isobutane is produced, and TIBA containing a large amount of AlH ₃ or DIBAH is produced. That is, it was found that TIBA was not quantitatively produced and a large amount of DIBAH was by-produced when the supplied isobutylene was completely reacted. Further, it was found that DIBAH is never lost even if a necessary amount or more of isobutylene is added and reacted in order to convert DIBAH into TIBA, and it remains together with a certain amount of isobutylene.

In Example 1 of Japanese Examined Patent Publication (Kokoku) No. 32-5710, isobutene (1.8 kg, 32.1 mol) is added to T.
1500 ml of IBA (6.0 mol at a density of 0.788 g / ml) was produced. And, although it is described that a small amount of isobutane is released, there is no description about the residual isobutylene concentration as in the method of the present invention. It is considered that this is because the reaction of isobutylene was exhausted, but it is considered that a large amount of DIBAH was produced. As a result, the yield based on isobutylene was 56%, which is remarkably low as compared with the present invention.

Furthermore, the present inventors have found that in the range from a large excess of isobutylene concentration to the i-butylene concentration of the present invention, the production rate of TIBA (DIBAH is i-Bu).
From the existing amount of groups, it is converted into 2 / 3.TIBA. ) Is i
It was found to be constant regardless of the butylene concentration.
As a result, even if the isobutylene concentration is maintained at a low level as in the present invention, TIB is not required even in the case where a large amount is initially charged as in a batch reaction.
The production rate of A does not decrease, and the advantage of the present invention is that only the production rate of DIBAH decreases. Particularly, Ti or Zr is 0.01 to 1.0 wt.
It has been found that when an aluminum Al alloy containing 100% is used, TIBA production rate is improved several times while maintaining the above characteristics, which is more preferable.

As is clear from the above description, the method of the present invention reduces the DIBAH in TIBA and significantly improves the yield of TIBA by leaving a specific concentration of isobutylene at the end of the TIBA synthesis reaction. I was able to.

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

Example 1 A 1 liter electromagnetic stirring type autoclave was used as a reaction apparatus, which was provided with an isobutylene gas, hydrogen gas, and a continuous aluminum aluminum powder inlet and an outlet for continuously extracting TIBA purified by the reaction. It was The unreacted metallic aluminum powder in the reactor was filtered with a filter so as not to go out of the system. 80 g of activated aluminum alloy powder containing 0.15 wt% of Ti and TIBA40 in the reaction tank.
0 g (1.2 g of AlH ₃ was dissolved), 25.7 g of isobutylene and 19.6 g of isobutane were charged and stirring was started. The reaction system was maintained at a hydrogen pressure of 9.2 kg / cm ² and a total pressure of 17 kg / cm ² . Isobutylene 2 from the charging port
3.4 g / hr (0.42 mol / hr), hydrogen 0.2 g
/ Hr (0.10 mol / hr), Ti 0.15 wt%
Aluminum alloy powder contained 3.24 (0.12 mol /
hr) was continuously charged and reacted at a reaction temperature of 130 ° C. and a residence time of 17.1 hr.

From the outlet, TIBA 23.3 g / hr
(0.118 mol / hr) AlH ₃ 0.07 g / hr
(0.0023 mol / hr), 1.61 g of isobutylene
(0.0288 mol / hr), isobutane 1.14 g /
hr (0.0197 mol / hr) was extracted. The isobutylene concentration in the system was 0.047 g / ml, the AlH ₃ content in the resulting solution was 0.3 wt%, and the DIBAH
Content was 4.3 wt%.

Examples 2 and 3 and Comparative Examples 1, 2 and 3 The isobutylene concentration in the reaction system was changed as shown in Table 1.
An experiment was conducted in the same manner as in Example 1. The results are shown in Table 1.
You From this, AlH in the produced crude TIBA₃Content rate
To control in the range of 0.2wt% to 0.7wt%
The isobutylene concentration at the end of the reaction is 0.
Need to range from 02 g / ml to 0.08 g / ml
I know there is. Isobutylene concentration outside this range
If it is 0.015 g / ml, AlH ₃The content rate is 1.
0wt%, that is, it is DIBAH 14.2w
tBA is present, and TIBA in the reaction solution is 85.
As low as 8%, and in the purification process, DIBAH or A
lH₃The yield is further reduced by the influence of. on the other hand,
Al at an isobutylene concentration of 0.15 g / ml or more
H₃The concentration is 0.1 wt%, and TIB in crude TIBA is
The purity of A is as high as 98.6%.
Initial charging to maintain a butylene concentration of 0.15 g / ml
Discharge or recover 25% of isobutylene as unreacted residue
It must be done and it is not economical.

[0028]

[Table 1]

[0029]

According to the present invention, the concentration of diisobutylaluminum hydride (DIBAH) can be suppressed to a low level (that is, the concentration of AlH ₃ can be suppressed to a low level), the amount of isobutane by-produced can be suppressed, and triisobutylaluminum ( It has become possible to continuously produce TIBA in which TIBA is obtained in high yield. As a result, TIBA can be manufactured at an extremely low cost, which is a great advantage to the industry.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kiyoshi Yamamura, 1-6 Takasago, Takaishi, Osaka Prefecture Mitsui Toatsu Kagaku Co., Ltd. (72) Masahiko Aso, 1-6, Takasago, Takaishi, Osaka Mitsui Toatsu Kagaku Within the corporation

Claims (4)

[Claims] 1. In a reaction for synthesizing triisobutylaluminum in a continuous manner from aluminum, hydrogen and isobutylene in the presence of triisobutylaluminum, isobutylene of 0.02 g / ml to 0.08 g / ml is added in the reaction system. A method for producing triisobutylaluminum, characterized in that it remains within the range. 2. Aluminum has a Ti or Zr content of 0.0
The method for producing triisobutylaluminum according to claim 1, which is an aluminum alloy containing 1 to 1.0 wt%. 3. The method for producing triisobutylaluminum according to claim 1, wherein the reaction is carried out at a temperature range of 100 to 200 ° C. and a hydrogen partial pressure range of 1 to 250 kg / cm ² . 4. The method for producing triisobutylaluminum according to claim ² , wherein the reaction is carried out at a temperature range of 120 to 140 ° C. and a hydrogen partial pressure range of 1 to 12 kg / cm ² .