JP5343041B2 - Process for producing olefin polymer - Google Patents

Description

  In the present invention, a liquid hydrocarbon raw material containing a olefin having 4 carbon atoms as a main component, obtained from raffinate (extraction residual oil) when producing diene hydrocarbons by extractive distillation, in the presence of an acid catalyst, The present invention relates to a method for producing an olefin polymer which is polymerized after adjusting the water concentration.

  Diene hydrocarbon is used as an extract from the hydrocarbon mixture mainly composed of C4 hydrocarbons including diene, olefin, and saturated aliphatic hydrocarbon obtained as a cracked product of petroleum. The raffinate obtained when producing dienes by the extractive distillation method mainly contains olefins having 4 carbon atoms. When a hydrocarbon containing this olefin having 4 carbon atoms is subjected to a polymerization reaction in the presence of a liquid acid catalyst such as a Lewis acid to obtain an olefin polymer, A 1 C 13, B F 3 And halogen-containing acid catalysts such as TiCl4 are preferably used. When these halogen-containing acid catalysts such as AlCl3, BF3, TiCl4 remain in the olefin polymer as they are, they will deteriorate the transparency of films, sheets and other products in the long term, or Deterioration of the commercial value is caused by the remaining halogen-based impurities. Therefore, normally, the catalyst is deactivated and removed, and these treatment steps usually include complicated steps including steps such as deactivation with an alkaline aqueous solution, extraction, separation, purification, filtration, and the like. In particular, if the catalyst is soluble in the reaction solution in the olefin polymerization step, there are problems such as deactivation by an alkaline aqueous solution or the like and difficulty in performing extraction with high efficiency.

By the way, increasing the efficiency of the acid catalyst and reducing the amount of use not only reduces the catalyst cost, but also reduces the burden of the catalyst deactivation process and the removal process. One of the solutions. For this purpose, it is effective to use a catalyst that dissolves in the reaction system, to allow the reaction to proceed in a homogeneous system, and / or to make the catalyst highly active.
However, halogen-containing acid catalysts such as AlCl3 and BF3 can be combined with a ligand to increase the activity, but the halogen-containing acid catalyst itself is a hydrocarbon constituting the reaction solution. It does not dissolve and is insoluble in the hydrocarbon constituting the reaction solution even when a ligand is combined. On the other hand, the soluble catalyst has a problem in post-treatment that it is difficult to deactivate and extract with an alkaline aqueous solution as described above with high efficiency.

  In addition, in the polymerization reaction of a C4 olefin by an acid catalyst, addition of a proton donor (proton donor) is essential. Alcohol or water is mainly used as the proton donor. However, if the amount of alcohol or water is too large, the acid catalyst itself is decomposed and rather acts as a deactivator. Therefore, it is necessary to supply an appropriate amount of proton donor to the acid catalyst, but the appropriate ratio has not always been clear. In particular, the alkylaluminum chloride catalyst soluble in the polymerization reaction solution was completely unknown. When an alkylaluminum chloride-based catalyst that is soluble in the polymerization reaction solution is used as the acid catalyst, the catalyst concentration in the reaction solution is generally an extremely small value (Patent Document 1). In such cases, the appropriate amount of proton donor added is generally very small. When a proton donor is added directly to the polymerization reaction solution, it tends to be excessively added. In particular, when water is used as a proton donor, if it is added directly, it tends to be excessive with respect to the catalyst, and it is liable to cause adverse effects such as generation of free water exceeding the water solubility of the reaction solution. (Patent Document 1)

JP 2005-30699 A

  An object of the present invention is a raffinate of an extractive distillation method using a diene hydrocarbon as an extract, the raw material being a liquid hydrocarbon containing a olefin having 4 carbon atoms as a main component, and being soluble in hydrocarbon. In a method for producing an olefin polymer using a catalyst, the catalyst efficiency is improved by adjusting the amount of water with respect to the acid catalyst, and further, a method with high accuracy and good workability for adjusting the amount of water Is to provide.

That is, the first of the present invention is a hydrocarbon containing 5 to 95% by mass of an olefin containing 4 olefins as a main component and a hydrocarbon obtained from a raffinate of an extractive distillation method using a diene hydrocarbon as an extract and 4 carbon atoms. Liquid hydrocarbon composed of 95 to 5% by mass of saturated aliphatic hydrocarbon containing 100% by mass of saturated aliphatic hydrocarbon as a main component in the presence of an acid catalyst. The liquid hydrocarbon is added, and the water content is adjusted to a molar ratio of 0.1 to 0.5 with respect to the acid catalyst, and then a part or all of the olefin is polymerized. A method for producing an olefin polymer, wherein the acid catalyst is a halogen-containing acid catalyst and is any one of the following formulas (1) and (2): .
AlRmXn (1)
(Wherein R represents an alkyl group having 1 to 8 carbon atoms, X represents a halogen atom, and m and n are 1 or 2 and n = 3- m ).
Al ₂ RpXq (2)
(Wherein R represents an alkyl group having 1 to 8 carbon atoms, X represents a halogen atom, p is an integer of 1 to 5 and q is an integer of 1 to 5 and p + q = 6) It is in.)

A second aspect of the present invention relates to a method for producing an olefin polymer according to the first aspect of the present invention, wherein the olefin contains isobutene.

A third aspect of the present invention relates to a method for producing an olefin polymer according to the first or second aspect of the present invention, wherein the halogen-containing acid catalyst is hydrocarbon-soluble.

A fourth aspect of the present invention relates to a method for producing an olefin polymer according to any one of the first to third aspects of the present invention, wherein the halogen-containing acid catalyst is ethylaluminum dichloride.

  According to the method of the present invention, an olefin polymer is produced in the presence of a Lewis acid catalyst such as a halogen-containing acid catalyst using, as a raw material, an aliphatic hydrocarbon containing a olefin having 4 carbon atoms obtained from a raffinate obtained by extractive distillation. In the method, the efficiency of the catalyst can be increased, the amount of the catalyst used can be reduced, and the production cost for the catalyst can be reduced. Moreover, since the adjustment of the amount of proton donor such as water or alcohol can be easily adjusted, the workability of the polymerization reaction can be improved. Further, the catalyst deactivation and / or removal step after the polymerization reaction can be simplified or omitted.

Hereinafter, the present invention will be described in detail.
The olefin polymer of this invention means the polymer which has a C4 olefin which has a double bond at the terminal as a main component. In the present invention, as a starting material for obtaining an olefin polymer, an olefin content of 5 to 95% by mass containing a olefin having 4 carbon atoms as a main component, obtained from an extractive distillation raffinate using a diene hydrocarbon as an extract. And a liquid hydrocarbon composed of 95 to 5% by mass of a saturated aliphatic hydrocarbon containing a C4 saturated aliphatic hydrocarbon as a main component (both are 100% by mass in total). Examples of the raw material for extractive distillation include a mixture of diene, olefin and saturated aliphatic hydrocarbon obtained in the petroleum refining or petrochemical industry. For example, as a raw material for obtaining butadiene, it is mainly referred to as a C4 fraction (C4 fraction, crude butadiene, BB fraction, etc.) produced when ethylene / propylene or the like is produced by naphtha decomposition. A similar fraction can be obtained by high-temperature decomposition of gas oil. Or what is obtained from the decomposition product of petroleum by fluid catalytic cracking (FCC), the catalytic dehydrogenation reaction product of butane, butene, etc. can be used. A C4 fraction containing pentane or pentene as impurities can also be used. When obtaining isoprene which is a diene having 5 carbon atoms, a raw material fraction having 5 carbon atoms obtained by the above-described method such as naphtha cracking is used.

  Separation of a diene such as butadiene from such a diene-containing raw material is impossible by simple distillation because the boiling points of many compounds are close to each other and an azeotrope is formed. Therefore, diene is widely obtained by extractive distillation using a solvent. The extractive distillation method used in the present invention is not particularly limited, and any known extractive distillation method can be preferably used.

  Specific examples of the extractive distillation method for producing butadiene will be given. In the case of isoprene, the process is almost the same. When the vaporized C4 fraction is fed from the lower part of the extraction tower and the extraction solvent is added from the upper part of the extraction tower, the apparent boiling point of butadiene rises due to the interaction between the solvent and butadiene and shifts to the bottom of the tower. The hydrocarbon containing olefin and paraffin is distilled from the top of the column as a raffinate containing an extraction solvent, and the fraction containing butadiene and the like is extracted from the bottom of the column as an extract together with the extraction solvent. The extraction solvent accompanying the raffinate containing the extraction solvent is recovered from the raffinate by a method such as irrigation water washing in a washing tower. Furthermore, it is preferable to remove dienes contained in a trace amount and hydrocarbons having an acetylene bond by hydrogenation by a known method. Hereinafter, the term “raffinate” in the present specification refers to a product obtained by distilling from the extractive distillation column and then separating the extraction solvent in the extraction solvent separation step, unless otherwise specified.

  As the olefin, those having a vinyl group, that is, those having a double bond at the terminal are particularly preferred. For example, 1-butene and 2-methyl-1-propene (isobutene) are used as olefins having 4 carbon atoms, 3-methyl-1-butene and 1-pentene are used as olefins having 5 carbon atoms, and 1-hexene and vinyl are also included. Examples include cyclohexane, 4-methyl-1-pentene, 2,4,4-trimethyl-1-pentene, 1-decene, and 1-dodecene. In view of the ease of keeping the reaction system containing the produced polymer and the raw material hydrocarbon in a liquid state, the reactivity of the olefin, etc., those containing 4 carbon atoms are most preferred.

  When the olefin content is 5% by mass or less, the production efficiency of the olefin polymer is low, and it is difficult to obtain a polymer industrially. On the other hand, if it exceeds 95% by mass, the viscosity of the reaction system becomes too high particularly during the production of an olefin polymer having a large molecular weight, and the polymerization reaction process may not be carried out smoothly. The olefin content is, for example, in the step of producing a polymer (polybutene) having a number average molecular weight of 1500 to 10000 from a hydrocarbon containing isobutene, which is an olefin having 4 carbon atoms, and the isobutene concentration is in the range of 20 to 70% by mass. It is preferable that it exists in the range of 25-60 mass%.

  Hydrocarbons mainly containing olefins with 4 carbon atoms are easily marketed as raffinates when butadiene is produced by the extractive distillation method from C4 fractions produced from so-called naphtha cracking equipment that produce lower olefins such as ethylene and propylene. Can be obtained. The raffinate usually contains isobutene in the range of 40-55% by weight and 1-butene in the range of 10-15% by weight as olefin, and additionally contains 7-8% by weight of 2-butene. Butadiene is 0.5 mass% or less and contains a trace amount of extraction solvent. The balance is saturated hydrocarbons such as butane and isobutane. Of course, other raffinates or saturated hydrocarbons can be added to the raffinate.

The acid catalyst in the present invention is not particularly limited as long as it is a known acid catalyst for olefin polymerization, but is preferably a halogen-containing catalyst from the viewpoint of solubility in raw material hydrocarbons and activity. Examples thereof include chlorine-based catalysts, fluorine-based catalysts, and complex catalysts thereof (see US Pat. Nos. 4,152,499, 5,408,018, and 5,068,490).
The catalyst may be supplied after being diluted with a suitable solvent such as normal hexane, normal heptane, isooctane, cyclohexane, cyclododecane, toluene, benzene, dichloromethane, methyl chloride, ethyl chloride and the like.

The preferred catalyst for obtaining the olefin polymer according to the present invention with particularly high efficiency is a highly acidic catalyst or a catalyst that dissolves in the reaction system, and is particularly represented by the following formula (1) or (2): It is.
Al R m Xn (1)
(Wherein R 1 represents an alkyl group having 1 to 8 carbon atoms, X represents a halogen atom, m 1 and n 2 are 1 or 2, and m + n = 3)
Al2 R p Xq (2)
(Wherein R 1 represents an alkyl group having 1 to 8 carbon atoms, X represents a halogen atom, p is an integer of 1 to 5 and q is an integer of 1 to 5 and p + q = 6 It is in a relationship.)
Among these, preferred catalysts are C H3 A 1 C 12, (C H3) 2 A 1 C 1, C 2 H 5 A 1 C 1 2, (C2 H5) 2 A 1 C 1, (C2 H5) 3 A 1 2 C l3, (CH3) 3CAlCl2 and [(CH3) 3C] 2AlCl. Particularly preferred is highly safe C2H5AlCl2 (ethylaluminum dichloride).

  The liquid hydrocarbon containing substantially saturated water may be shaken after adding water to the hydrocarbon not containing olefin, and the supernatant thereof may be used. Alternatively, a recovered C4 fraction that has been distilled and separated through a catalyst deactivation step after completion of the polymerization reaction can be used. These are introduced into the reactor after controlling the flow rate and adjusting the water to a molar ratio of 0.1 to 0.5 with respect to the acid catalyst. In addition, the molar ratio is the above-mentioned “saturated aliphatic hydrocarbons 95 to 5 mass% including olefins 5 to 95 mass% mainly containing olefins having 4 carbon atoms and saturated aliphatic hydrocarbons 4 carbon atoms as main ingredients. The amount of water brought in from “liquid hydrocarbons consisting of%” is also a calculated value. There are no particular restrictions on hydrocarbons that do not contain olefins, but hydrocarbons having 4 or more carbon atoms are preferred from the standpoint of maintaining a liquid phase at the polymerization temperature. For example, hexane, heptane, octane, toluene, benzene, xylene and the like are preferably used.

  The polymerization reaction is carried out in a liquid phase using raw material hydrocarbons and catalyst that have been treated with an aluminum atom-containing treating agent. The reaction can be carried out by either a batch method or a continuous method, but a continuous method is preferred from the viewpoint of efficient production. A well-known thing can be used for a reaction apparatus. The raw material hydrocarbon and catalyst are supplied by a known method. The polymerization temperature and pressure are not particularly limited as long as the reaction system is maintained in a liquid phase, but a preferred temperature is −40 to + 10 ° C. and a pressure is 0.1 to 2 MPa.

  The number average molecular weight of the olefin polymer is such that the olefin polymer is dissolved in the unreacted olefin and saturated aliphatic hydrocarbon in the polymerization reaction system, and from the unreacted olefin and saturated aliphatic hydrocarbon. There is no limitation as long as it can be separated by distillation or the like. According to the present invention, from hydrocarbons containing 15 to 45% by mass of isobutene, which is an olefin having 4 carbon atoms, oligomers having a number average molecular weight of 500 or less from dimers and trimers, a number average molecular weight of 1, Since it includes a wide range of viscous polymers in the range of 500 to 50,000 and polymer polymers having a number average molecular weight of 100,000 or more, an isobutene polymer having an appropriate commercial value can be obtained.

  After the polymerization, a catalyst deactivation step and / or a catalyst extraction / removal step are performed according to a known method. However, since the amount of catalyst addition is reduced, the energy load and environmental load required for these steps are reduced. Compared to conventional methods. Further, before and after these steps, unreacted olefins and the like are appropriately removed by distillation to obtain the desired polymer. Further, the polymer thus obtained can be further appropriately distilled under reduced pressure to be separated into an olefin polymer having a desired number average molecular weight. In the present invention, since the amount of catalyst added is reduced, a polymer having a halogen concentration of 5 ppm or less can be easily obtained by installing a dehalogenation treatment tower (for example, an alumina packed tower).

  As mentioned above, the explanation has been given mainly using the butene-based olefin polymer as an example, but the effect according to the present invention is not limited to the butene-based olefin polymer as long as it is the olefin described in paragraph [0017].

  The method for producing an olefin polymer according to the present invention and the olefin polymer obtained by the method have a low production cost for the catalyst because the amount of the catalyst added is reduced, and the load for deactivation and removal of the catalyst is small. The cost relating to the equipment is low, and the catalyst residue in the obtained olefin polymer is extremely small. In particular, when a halogen-containing catalyst is used, even when a lubricating oil additive such as a detergent made of the olefin polymer is burned, the release of halogen into the atmosphere is small, and therefore in terms of environmental conservation. Useful. Further, since the addition amount of a proton donor such as water or alcohol as a co-catalyst is easily adjusted, high catalytic activity is obtained, and the addition amount can be easily adjusted. Contributes to the reduction of manufacturing costs.

Hereinafter, although an example is given and explained, the present invention is not limited to an example.
<Example 1>
(Polymerization process)
A raw material was obtained by diluting the remaining raffinate fraction obtained by extracting butadiene from a C4 fraction obtained from an ethylene production apparatus by naphtha decomposition with isobutane. The raw material composition analyzed by gas chromatography is shown in Table 1. This was passed through a cylinder filled with alumina and molecular sieves 3A for dehydration and impurity removal treatment. The water content in the raw material after the treatment was 0.10 ppm. This raw material was fed to an autoclave having an internal volume of 500 ml per hour. Furthermore, a predetermined amount of isooctane having saturated water (80 ppm) for adjusting water and 1% ethylaluminum dichloride / isooctane solution as a catalyst solution were supplied by a liquid chromatography pump, and line mixing was performed. The supply amount of isooctane having saturated water (80 ppm) was adjusted, so that the water content in the raw material was 0.4 ppm. While supplying these raw materials, polymerization was continuously carried out at a reaction pressure of 0.3 MPa and a reaction temperature of -7 ° C. At that time, the polymerization was carried out while adjusting the supply amount of the catalyst solution, and the reaction was continued when the isobutene conversion rate described later was stabilized at 60%, and the water / catalyst molar ratio and the catalyst / isobutene molar ratio were determined.

飽和水分（80ｐｐｍ）を持つイソオクタンを混合後の原料供給量（毎時２８０ｇｒ）と、イソブテン転化率が６０％となるように調整したエチルアルミニウムジクロライド／イソオクタン溶液の供給量とから、供給原料中の水分／触媒（モル比）およびそのときの触媒／イソブテン（モル比）を求めた結果を表２に示す。水分／触媒のモル比は０．１７であり、イソブテン転化率が６０％となる触媒／イソブテンモル比は１．５×１０^−５であった。 <Calculation of conversion of isobutene to polyisobutene>
The raw material before the polymerization reaction and the reaction liquid after the polymerization reaction (including polyisobutene) were sampled in sealed containers, respectively. The reaction solution after the polymerization reaction was neutralized with an aqueous sodium hydroxide solution to deactivate the catalyst, kept at room temperature and normal pressure, and then analyzed for isobutene concentration in the evaporated gas component by gas chromatography. The isobutene concentration of the raw material before the polymerization reaction was also analyzed by gas chromatography. The conversion rate (%) of isobutene to polyisobutene was determined from the following equation.

Moisture in the feedstock from the feed rate of raw material (280 gr / h) after mixing isooctane with saturated moisture (80 ppm) and the feed rate of ethylaluminum dichloride / isooctane solution adjusted so that the isobutene conversion is 60% Table 2 shows the results of determining / catalyst (molar ratio) and catalyst / isobutene (molar ratio) at that time. The water / catalyst molar ratio was 0.17, and the catalyst / isobutene molar ratio at which the isobutene conversion was 60% was 1.5 × 10 ⁻⁵ .

<Example 2>
The same operation as in Example 1 was conducted except that the water content in the raw material after mixing with isooctane having saturated water content (80 ppm) was 1.5 ppm. Similarly, the water / catalyst molar ratio in the feedstock was 0.28, and the catalyst / isobutene molar ratio at which the isobutene conversion was 60% was 3.5 × 10 ⁻⁵ .

<Comparative Example 1>
Polymerization was carried out in the same manner as in Example 1 except that the water content in the raw material after mixing with isooctane having saturated water content (80 ppm) was 0.8 ppm, but the supply amount of the catalyst solution was 1 in molar ratio of catalyst / isobutene. The polymerization of isobutene did not proceed even at 0.0 × 10 ⁻⁴ . At this time, the molar ratio of water / catalyst was 0.05 as shown in Table 2.

<Comparative Example 2>
The same procedure as in Example 1 was conducted except that the water content in the raw material after mixing with isooctane having saturated water content (80 ppm) was 9 ppm. Similarly, the water / catalyst molar ratio in the raw material was 0.65, and the catalyst / isobutene molar ratio at which the isobutene conversion was 60% was 1.0 × 10 ⁻⁴ .

表２の結果から、供給原料中の水分／触媒（モル比）が低すぎると活性が無く、高すぎると余計に触媒を必要とすることがわかる。 Table 2 shows the water / catalyst molar ratios obtained in Examples and Comparative Examples, and the catalyst / isobutene molar ratio at which the isobutene conversion is 60%.

From the results in Table 2, it can be seen that if the moisture / catalyst (molar ratio) in the feedstock is too low, there is no activity, and if it is too high, an extra catalyst is required.

  In a method for producing an olefin polymer using a catalyst containing an aliphatic hydrocarbon containing a olefin having 4 carbon atoms obtained from extraction residue of extractive distillation, the production cost for the catalyst is reduced, and the polymerization reaction The operability of the manufacturing process can be improved by simplifying or omitting the subsequent catalyst deactivation and / or removal process.

Claims (4)

5 to 95% by mass of olefins mainly containing olefins having 4 carbon atoms and saturated aliphatic hydrocarbons having 4 carbon atoms, including hydrocarbons obtained from extractive residue using diene hydrocarbon as an extract by extractive distillation In the presence of an acid catalyst, a liquid hydrocarbon containing saturated water is added to a liquid hydrocarbon which is composed of 95 to 5% by mass of a saturated aliphatic hydrocarbon containing 95 to 5% by mass as a main component. Then, the water content is adjusted so that the molar ratio of the acid catalyst is 0.1 to 0.5, and then a part or all of the olefin is polymerized. The method for producing an olefin polymer is characterized in that the acid catalyst is a halogen-containing acid catalyst and is any one of the following formulas (1) and (2).
AlRmXn (1)
(Wherein R represents an alkyl group having 1 to 8 carbon atoms, X represents a halogen atom, and m and n are 1 or 2 and n = 3- m ).
Al ₂ RpXq (2)
(Wherein R represents an alkyl group having 1 to 8 carbon atoms, X represents a halogen atom, p is an integer of 1 to 5 and q is an integer of 1 to 5 and p + q = 6) It is in.)   The said olefin contains isobutene, The manufacturing method of the olefin polymer of Claim 1 characterized by the above-mentioned. Process for producing an olefin polymer according to claim 1 or 2, wherein the halogen-containing acid catalyst is a hydrocarbon soluble. The method for producing an olefin polymer according to any one of claims 1 to 3 , wherein the halogen-containing acid catalyst is ethylaluminum dichloride.