JPS628110B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for selectively polymerizing isobutene and removing it from an isobutene-containing mixture whose main component is a hydrocarbon having 4 carbon atoms.

More specifically, by contacting an isobutene-containing mixture mainly composed of a hydrocarbon having 4 carbon atoms with an anhydrous aluminum chloride catalyst dissolved in nitroparaffin at a relatively high temperature above room temperature, or more preferably, R ¹ −O−R ³ −O−R ² (However,
R ¹ and R ² represent a phenyl group, an alkyl group, or an alkenyl group, and R ¹ and R ² may be the same or different groups. Also, R ³ is −CH ₂ −, −C ₂ H ₄ −, −C ₃ H ₆ −,
or _{-C 2} H _{4 .O} . , relates to a method for selectively removing isobutene from an isobutene-containing mixture by converting it into a polymer having a narrow molecular weight distribution without substantially reducing normal butene.

Obtained by steam cracking of butane, normal butene, and isobutene fractions obtained by fluid catalytic cracking of heavy oil, etc., or naphtha fractions.
A mixture of butane, normal butene, isobutene fractions, etc. obtained by removing butadiene from the _C4 fraction can be used as an industrial raw material.For example, a plasticizer alcohol can be produced from the dimerization reaction product using the oxo method. It can be a useful raw material when obtaining. However, the presence of isobutene is said to interfere with the dimerization process, and it is desirable to separate isobutene from these mixtures without reducing the amount of normal butene before sending these mixtures to the dimerization process.

As a method for removing isobutene from an isobutene-containing mixture, for example, there is a method in which isobutene is polymerized by contacting butane, normal butene, and isobutene fractions with a polymerization catalyst, and then separated from other _C4 components by distillation, etc. However, this has already been carried out industrially as a method for producing so-called polybutene. The industrial method for producing polybutene uses an anhydrous aluminum chloride catalyst dissolved or suspended in a saturated hydrocarbon, and the reaction temperature is -29
Conventionally, a method of carrying out polymerization at a low temperature of .degree. C. to 27.degree. C. has been used.

However, this known method is not a satisfactory method when the purpose is to remove isobutene from a butane-butene mixture without substantial reduction of normal butene. That is, the first
Furthermore, in order to carry out this polymerization reaction, which generates a large amount of heat, at a low temperature, additional equipment such as a refrigerator is required, making the process complicated and inevitably consuming a large amount of energy for cooling. Second, when polybutene is produced from a mixture of butane, normal butene, and isobutene by a known method, a considerable amount of normal butene is polymerized simultaneously with the polymerization of isobutene, resulting in a substantial decrease in normal butene. It is difficult to selectively polymerize only isobutene without accompanying it.

For example, at the same time as 85% of isobutene in the raw material is polymerized, 30% of normal butene is polymerized. Third
In addition, in reactions at relatively high temperatures above room temperature, it becomes difficult to control the molecular weight distribution of the resulting polymer, and the proportion of light boilers in the product increases, resulting in a significant decrease in the yield of the polymer. decreases rapidly.

The inventors of the present application have discovered that at relatively high temperatures above room temperature,
As a result of extensive research into a method for selectively converting isobutene into a polymer with a narrow molecular weight distribution and removing it from an isobutene-containing mixture, the present invention has been achieved.

That is, by using anhydrous aluminum chloride dissolved in nitroparaffin as a catalyst, butane and
Even though normal butene and isobutene fractions are reacted at a relatively high temperature above room temperature, the reaction of normal butene is significantly suppressed, and isobutene is selectively polymerized, accompanied by a substantial decrease in normal butene. It has been found that isobutene can be removed as a polymer from butane, normal butene, and isobutene fractions without any problems, and that the molecular weight distribution of the resulting polymer becomes significantly narrower.

Furthermore, the general formula R ¹ -O-R ³ -O-R ² (however, R ¹ ,
R ² represents a phenyl group, an alkyl group, or an alkenyl group, and R ¹ and R ² may be the same or different groups.
Also, R ³ is −CH ₂ −, −C ₂ H ₄ −, −C ₃ H ₆ −, or −
By bringing anhydrous aluminum chloride catalyst dissolved in nitroparaffin into contact with butane, normal butene, and isobutene fractions in the presence of a compound represented by C ₂ H ₄・O ・C ₂ H ₄ - Despite the relatively high reaction temperature above room temperature, the reaction of normal butene is further significantly suppressed, and isobutene is more selectively polymerized, resulting in isobutene being converted into isobutene without a substantial decrease in normal butene. butane as a polymer.
It has been found that it can be removed from normal butene and isobutene fractions, and that the molecular weight distribution of the resulting polymer becomes even more narrow.

Here, nitroparaffin means mononitroalkanes, including nitromethane, nitroethane,
Examples include nitropropane.

Further, compounds represented by the general formula R ¹ -O-R ³ -O-R ² include diphenoxyalkanes such as diphenoxymethane, diphenoxyethane, and diphenoxypropane, dimethoxymethane, dimethoxyethane, dimethoxypropane, dimethoxybutane,
Alkoxy alkanes such as diethoxymethane, diethoxyethane, dipropoxymethane, dipropoxyethane, diproxypropane, dipropoxybutane, diptoxymethane, dipoxyethane, diptoxypropane, diptoxybutane, methoxy/ethoxymethane, ethoxypropoxyethane, phenoxy/methoxy Examples include phenoxy alkoxy alkanes such as methane and phenoxy ethoxyethane, and diethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether.

The anhydrous aluminum chloride dissolved in nitroparaffin can be used in an amount ranging from 0.02 mol to saturated solubility per 1 mol of nitroparaffin.

In addition, the compound represented by R ¹ -O-R ³ -O-R ² is 50ppm based on the butane/butene fraction of the raw material.
It can be used at a rate of ~10000ppm (capacity).

Moreover, as the raw material butane/butene fraction, it can be applied to any butane/butene fraction containing isobutene generated in petroleum refining or petrochemical industry.

As the reaction method used in the present invention, either a batch reaction method or a continuous reaction method can be adopted.

The present invention will be described in detail below with reference to Examples, but these Examples are not intended to limit the present invention.

Example 1 47 g of anhydrous aluminum chloride was dissolved in 250 ml of nitromethane under a nitrogen atmosphere to prepare an aluminum chloride catalyst solution. Autoclave hebutane 12.0% with jacket and stirrer with internal volume of 280ml,
200 ml of butane/butene fraction with a composition of 43.5% isobutene, 19.2% 1-butene, and 25.3% 2-butene.
hr, 2ml/hr of the above aluminum chloride catalyst solution
The reaction was carried out at a pressure of 7 kg/cm ² G and a reaction temperature of 51°C. The reaction system reached a steady state 5 hours after the start of the reaction. Gas chromatography analysis of the gas phase flowing out of the reactor after steady state showed that 80% of the isobutene and 8% of the normal butene in the raw materials had reacted. Further, the product after the steady state was distilled to remove up to the tetramer as light boiling substances, and the high boiling substances were analyzed by high performance liquid chromatography, and the number average molecular weight was 500. The proportion of high boiling substances in the product was 75%.

Example 2 1600 ppm (volume) of dimethoxyethane was dissolved in the butane/butene fraction used in Example-1.
The above butane/butene fraction containing dimethoxyethane was fed at a rate of 200 ml/hr and the above aluminum chloride catalyst solution was fed at a rate of 6 ml/hr into an autoclave equipped with a jacket and a stirrer with an internal volume of 280 ml, and the pressure was 7.
The reaction was carried out at Kg/cm ² G and reaction temperature of 51°C. The reaction system reached a steady state 5 hours after the start of the reaction. analysis,
Distillation etc. were carried out in the same manner as in Example-1. It was found that 83% of the isobutene and 4% of the normal butene in the raw materials had reacted. The proportion of high boilers in the product was 72%, and its number average molecular weight was 440.

Example 3 All the same as Example except that the reaction temperature was changed to 47.5℃.
The reaction was carried out under the same conditions as in 2. 75% of the isobutene and less than 1% of the normal butene in the raw material reacted. The proportion of high boilers in the product was 85%, and its number average molecular weight was 900.

Claims (1)

[Claims] 1. Isobutene is polymerized by contacting an isobutene-containing mixture mainly composed of a hydrocarbon having 4 carbon atoms with an anhydrous aluminum chloride catalyst dissolved in nitroparaffin at a reaction temperature range of 25°C to 60°C. A method for removing isobutene from an isobutene-containing mixture, comprising: separating the isobutene polymer from the reaction product. 2 An isobutene-containing mixture whose main component is a hydrocarbon having 4 carbon atoms is expressed by the general formula R ¹ -O-R ³ -O-R ²
(However, R ¹ and R ² represent a phenyl group, an alkyl group, or an alkenyl group, and R ¹ and R ² may be the same or different groups. Also, R ³ is -CH ₂ -, -C ₂ H ₄ - , −C ₃ H _6
- , _{or -C2H4.O.C2H4- .} ) in the reaction temperature range of 25°C to 60°C to polymerize isobutene by contacting it with an anhydrous aluminum chloride catalyst dissolved in nitroparaffin, and then separate the isobutene polymer from the reaction product. A method for removing isobutene from an isobutene-containing mixture, comprising: