JP5227490B2 - Process for producing olefin polymer - Google Patents

Description

  In the present invention, a liquid hydrocarbon raw material mainly containing a olefin having 4 carbon atoms obtained from a raffinate produced by distillate-based hydrocarbon production by an extractive distillation method is treated with a treating agent and then in the presence of an acid catalyst. The present invention relates to a method for producing a polymerized olefin polymer.

  Included in raffinate when diene is produced from a mixture of hydrocarbons containing diene, olefin and saturated aliphatic hydrocarbon such as cracked products of petroleum by extractive distillation using diene hydrocarbon as an extract When a liquid hydrocarbon mainly containing an olefin having 4 carbon atoms is subjected to a polymerization reaction in the presence of an acid catalyst such as a Lewis acid to obtain an olefin polymer, AlCl 3 is particularly preferably used with a focus on high activity. When the halogen-containing acid catalyst such as BF3, TiCl4 or the like remains in the olefin polymer as it is, it changes properties such as transparency of the product in the long term, or lowers the commercial value as a halogen-based impurity. Therefore, the catalyst is usually deactivated and removed. These treatment steps are complicated steps including steps such as extraction, separation, purification, and filtration with an alkaline aqueous solution. If it is dissolved in the reaction system in the process, it may be difficult to perform extraction with an alkaline aqueous solution or the like with high efficiency.

For example, increasing the efficiency of an acid catalyst to reduce the amount used reduces not only the cost of the catalyst, but also reduces the burden of the catalyst deactivation process and the removal process, which is one of the fundamental solutions. Become. For this purpose, it is effective to use a catalyst that dissolves in the reaction system, to advance the reaction in a homogeneous system, and / or to increase the activity of the catalyst.
However, the activity can be increased by combining a ligand with a halogen-containing acid catalyst such as AlCl3 or BF3, but the halogen-containing acid catalyst is insoluble in the hydrocarbon of the reaction system. On the other hand, the soluble catalyst has the problems in the post-treatment as described above.

As a method for increasing the efficiency of the polymerization reaction, it is conceivable to remove the polymerization inhibiting component contained in the raw material. In the method of producing tertiary butanol from isobutylene in extractive distillation method using diene hydrocarbon as extract as raw material, residual dimethylformamide in raw material is adsorbed using strongly acidic ion exchange resin A method of processing has been proposed (see, for example, Patent Document 1). However, when the olefin comes into contact with the strongly acidic ion exchange resin, the polymerization reaction of the olefin proceeds. Therefore, it is very difficult to divert the proposal to the polymerization reaction of the olefin.
JP 2000-34242 A

  An object of the present invention is a raffinate of an extractive distillation method using a diene hydrocarbon as an extract, a liquid hydrocarbon mainly containing an olefin having 4 carbon atoms as an olefin, and a hydrocarbon-soluble catalyst In the method for producing an olefin polymer using a catalyst, the influence of the extraction solvent is reduced or eliminated, the catalyst efficiency is improved, and the extraction with an alkaline aqueous solution or the like in the deactivation treatment and removal treatment of the catalyst is performed with high efficiency. It is to provide a method for reducing the burden of performing.

That is, the first aspect of the present invention is a olefin containing 5 to 95% by mass of an olefin containing mainly an olefin having 4 carbons and containing mainly a hydrocarbon obtained from a raffinate of an extractive distillation method using a diene hydrocarbon as an extract. A liquid hydrocarbon composed of 95 to 5% by mass of saturated aliphatic hydrocarbons containing saturated aliphatic hydrocarbons (both are 100% by mass in total) is contacted with an inorganic solid processing agent containing alumina, and then an acid. The present invention relates to a method for producing an olefin polymer, wherein a part or all of an olefin is polymerized in the presence of a catalyst.

The second of the present invention, Oite to a first aspect of the present invention, the olefin is a process for producing an olefin polymer which comprises 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 any one of the following formulas (1) and (2): It is.
AlRmXn (1)
(Here, 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 m + n = 3).
Al2RpXq (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 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.

A fifth aspect of the present invention relates to a method for producing an olefin polymer according to any one of the first to fourth aspects of the present invention, wherein the organic solvent used for the extractive distillation is dimethylformamide.

  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, the production cost of the catalyst can be reduced, and the subsequent catalyst deactivation and / or removal steps can be simplified or omitted. .

Hereinafter, the present invention will be described in detail.
The olefin polymer of the present invention means a polymer containing a C4 olefin having a double bond at the terminal as a main constituent component. In the present invention, as a starting material for obtaining an olefin polymer, an olefin content of mainly 5 to 95% by mass including mainly an olefin having 4 carbon atoms obtained from a raffinate of an extractive distillation method using a diene hydrocarbon as an extract, and mainly Liquid hydrocarbons composed of 95 to 5% by mass of saturated aliphatic hydrocarbons including saturated aliphatic hydrocarbons having 4 carbon atoms (both are 100% by mass in total) are used. 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. When obtaining isoprene which is a diene having 5 carbon atoms, a raw material fraction having 5 carbon atoms 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 the olefin according to the present invention flows out from the top of the column as a raffinate containing an extraction solvent, and flows out as an extract containing butadiene and the like from the bottom of the column. 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. However, even after such treatment, the raffinate usually contains a trace amount of a degradation product such as an extraction solvent and an oxide of the extraction solvent. The content is usually on the order of several tens of ppb to 10 ppm. Furthermore, it is preferable that hydrogenation and removal of dienes and hydrocarbons having an acetylene bond, which are contained in trace amounts, by hydrogenation by a known method if desired. Hereinafter, in the present specification, the term “raffinate” refers to a product obtained from an extractive distillation column and then subjected to an extraction solvent separation step, unless otherwise specified.

  Preferred extraction solvents in the extractive distillation of the present invention include furfural, acetonitrile, dimethylacetamide, dimethylformamide, N-methylpyrrolidone and the like. The extraction efficiency is preferably one that contains nitrogen, which is a highly polar organic solvent that has little interaction with olefins, etc., and its boiling point is sufficient compared to hydrocarbons in raffinate because of the ease of separation of hydrocarbons and solvents. Is preferably high. Therefore, among these, dimethylformamide and N-methylpyrrolidone are most preferable.

  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, 1-pentene and 1-hexene are used as olefins having 5 carbon atoms, and vinyl. 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 not commercial, and when it exceeds 95% by mass, the viscosity of the reaction system becomes too high particularly when producing an olefin polymer having a large molecular weight. Therefore, the process may not be performed smoothly. The olefin content is, for example, in the step of producing a carbon number 4 polymer (polybutene) having a number average molecular weight of 1500 to 10,000 from a hydrocarbon containing isobutene, which is a carbon number 4 olefin, and the isobutene concentration is 20 to 70 mass. %, Preferably in the range of 25-60 mass%.

  Hydrocarbons mainly containing olefins with 4 carbon atoms are easily obtained from the market as raffinates when butadiene is produced by extractive distillation from C4 fractions distilled from naphtha cracking equipment that produces lower olefins such as ethylene and propylene. can do. 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 polymerization raw material of the present invention obtained from the raffinate of the extractive distillation method using a diene hydrocarbon as an extract is unavoidably accompanied by a small amount of extraction solvent. The extraction solvent can interact with any compound present in the polymerization reaction system. In particular, those containing nitrogen preferable as an extraction solvent, for example, dimethylformamide, N-methylpyrrolidone and the like are strong in basicity, and are likely to cause a preferential and strong interaction with an acid catalyst, impairing the catalytic function. It is because there is a high possibility of giving.

In the present invention, the raw material hydrocarbon is brought into contact with the treatment agent containing aluminum atoms before the polymerization step, and at least a part of the extraction solvent is adsorbed on the treatment agent. The treatment agent containing an aluminum atom is preferably an inorganic solid treatment agent containing a component represented by the composition formula Al ₂ O ₃ . As long as the component represented by Al ₂ O ₃ is included, a natural or synthetic inorganic substance can be used. Specific examples of the inorganic solid treatment agent include alumina and silica / alumina. Alumina is preferred. These may be molded using an appropriate binder.

For example, commercially available alumina can be appropriately pulverized and classified for use. Although the surface area as a solid processing agent is not specifically limited, Usually, it is the range of 1-500 m < ² > / g. In addition, as long as the effect of the present invention is not hindered, the alumina is modified by appropriately impregnating an alkali metal, alkaline earth metal or other metal in an oxide, hydroxide or other form or by appropriately supporting it by other methods. Things can also be used. However, usually, such support / modification is not particularly necessary, and alumina having an alkali metal or alkaline earth metal content such as sodium of 0.5% by mass or less is used. Thus, alumina with little or no loading / modification is inexpensive, and the present invention is an advantageous method also in this respect. In addition, the alumina which can be preferably used in the present invention is activated alumina. It is also known as an amphoteric compound.

  The present inventor has found that the treatment agent containing an aluminum atom in the present invention has the characteristics of an amphoteric compound as an aluminum compound and the adsorptive power as an adsorbent. By this unique property, the olefin is substantially polymerized. It is considered that the residual extraction solvent in the raw material is physically adsorbed, or is adsorbed and removed particularly by the action of forming a coordination compound with a lone electron pair in the compound as the extraction solvent. That is, the residual extraction solvent can be adsorbed and removed without substantially proceeding with the polymerization reaction of olefins as compared with the adsorption removal by the strongly acidic ion exchange resin proposed in Japanese Patent Application Laid-Open No. 2000-34242.

  The temperature at which the aluminum atom-containing treatment agent is brought into contact with the liquid hydrocarbon raw material varies depending on the combination of the treatment agent and the type of olefin in the raw material hydrocarbon. If the treatment temperature is too high, the olefin polymerization reaction may proceed. If it is too low, the treatment effect cannot be sufficiently exhibited, and the subsequent polymerization process temperature is taken into consideration, and the temperature is set to -30 ° C to 100 ° C. It is preferable that the temperature is in the range of −10 ° C. to 50 ° C. In order to sufficiently obtain the effects of the present invention, it is preferable to bring the raw material hydrocarbon into contact with the aluminum atom-containing treatment agent in the liquid phase, and the treatment is performed while applying pressure as necessary.

  The contact time between the aluminum atom-containing treatment agent and the raw material hydrocarbon is not particularly limited as long as the removal of the extraction solvent is achieved, but a range of usually about 1 minute to 10 hours is preferable. When the length is shorter than this range, the contact is generally insufficient, and thus the extraction solvent is not sufficiently removed. As a method for contacting, either a batch type or a continuous type is possible. In the case of a continuous type, a fixed bed type, a fluidized bed type or the like can be used. As the flow direction, either an upflow or a downflow can be adopted.

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, 5,080,018, and 5068490).
The catalyst may be supplied diluted with an appropriate solvent such as normal hexane, normal heptane, isooctane, cyclohexane, cyclododecane, toluene, benzene, dichloromethane, methyl chloride, ethyl chloride, etc. For example, HCl, t-butyl chloride, water or the like may be supplied. The amount used is 0.5 x 10-5 to 1.0 x relative to the olefin having a terminal double bond in the raw material (this olefin is understood to be only for olefins having a terminal double bond). 10-2 (mol / mol) is preferable.

The catalyst which can obtain the effect according to the present invention with particularly high efficiency is a highly acidic catalyst or a catalyst which dissolves in the reaction system, and is particularly represented by the following formula (1) or (2).
AlRmXn (1)
(Here, R represents an alkyl group having 1 to 8 carbon atoms, X represents a halogen atom, m and n are 1 or 2, and m + n = 3.)
Al2RpXq (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.)
Among these, preferred catalysts include CH3AlCl2, (CH3) 2AlCl, C2H5AlCl2, (C2H5) 2AlCl, (C2H5) 3Al2Cl3, (CH3) 3CAlCl2 and [(CH3) 3C] 2AlCl. Particularly preferred is C2H5AlCl2 (ethylaluminum dichloride), which is highly safe.

  The polymerization reaction is carried out in the 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. 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 a hydrocarbon containing 15 to 45% by weight of isobutene, which is an olefin having 4 carbon atoms, an oligomer having a number average molecular weight of 500 or less from a dimer or trimer, a number average molecular weight of 1, An isobutene polymer having a commercial value including a wide range of a viscous polymer in the range of 500 to 50,000 and a polymer having a number average molecular weight of 100,000 or more can be obtained.

  After the polymerization, a catalyst deactivation step and / or a catalyst extraction / removal step is performed according to a known method. However, since the amount of the catalyst added is reduced, the load of these steps is larger than that of the conventional method. Become smaller. In addition, the target polymer is obtained by appropriately distilling before and after these steps to remove unreacted olefins and the like. Further, the polymer thus obtained can be further appropriately distilled to be separated into an olefin polymer having a desired number average molecular weight. In the present invention, since the catalyst addition amount is reduced, a polymer having a halogen concentration of 5 ppm by weight or less can be easily obtained by installing a dehalogenation tower (for example, an alumina packed tower). .

  As mentioned above, although the explanation has been given mainly using the butene-based olefin polymer as an example, the effect according to the present invention is not limited to the butene-based olefin polymer.

  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 small, and the catalyst residue in the obtained olefin polymer is small. In particular, when a halogen-containing catalyst is used, even when a lubricant additive such as a detergent comprising the derivative is burned, the release of halogen into the atmosphere is small, and thus it is useful in terms of environmental conservation. .

Hereinafter, although an example is given and explained, the present invention is not limited to an example.
<Raw material preparation and production (1)>
A raw material having a composition shown in Table 1 is prepared by mixing raffinate of an extractive distillation method (extraction solvent: dimethylformamide) with a butadiene extract and a reagent-grade isobutane at a mass ratio of 100: 60 from a C4 fraction from an ethylene cracker. Was prepared. The dimethylformamide concentration in the raw material was 0.7 mass ppm. Hereinafter, it is referred to as “raw material A”. The hydrocarbon composition in the raw material A is shown in Table 1. The concentration of dimethylformamide in the liquid hydrocarbon raw material containing olefin is determined by extracting the dimethylformamide in the raw material with water and concentrating it by evaporation, and then adjusting the concentration of dimethylformamide using GC-FTD (thermal ionization detector). It was calculated by using the result and back calculating from the result.

<Raw material preparation and production (2)>
Dimethylformamide was further added to “Raw material A” to prepare a dimethylformamide concentration of 1.5 mass ppm. Hereinafter, it is referred to as “raw material B”.
A C4 mixture (but not containing dimethylformamide) having the same composition as that of “Raw Material A” was prepared from a commercially available special grade reagent, and N-methylpyrrolidone added at 1.5 mass ppm was prepared. Hereinafter, it is referred to as “raw material C”.

<Aluminum atom-containing treatment agent>
A fixed bed container having an internal volume of 15 ml was charged with 10 g of a treatment agent obtained by pulverizing activated alumina (UOP LLC, trade name: A203-CL) and classifying the particle size from 0.5 mm to 1.0 mm. . For comparison purposes, the same shape container is filled with a reagent grade calcium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.) and classified into a particle size of 0.5 to 1.0 mm, and a molecular sieve. A material filled with MS13X (manufactured by Kishida Chemical Co., Ltd., 1/16 inch size) was prepared.

<Raw material contact treatment>
Raw materials A to C kept in a liquid state under a pressure of 0.3 MPa were poured into a treatment agent filled container and subjected to contact treatment under the conditions of + 20 ° C. and WHSV = 1h−1.

<Polymerization reaction>
Ethyl aluminum dichloride (EADC) diluted with methylene chloride as an acid catalyst was fed separately into an autoclave having an internal volume of 200 ml at 240 g / hr as the above treated raw materials A to C, respectively, and the reaction temperature was −15 ° C., 0.3 MPa. The polymerization was carried out continuously. The addition amount of the catalyst was 0.2 mmol and 0.3 mmol with respect to 1 mol of isobutene in each raw material.

<Calculation of conversion of isobutene to polyisobutene>
The raw material before the polymerization reaction and the polymer after the polymerization reaction (polyisobutene) are sampled in sealed containers, neutralized with an aqueous sodium hydroxide solution to deactivate the catalyst, and kept at room temperature and normal pressure. The isobutene mol% was analyzed by gas chromatography. The reduced amount of isobutene in the evaporated gas component was defined as the conversion rate (%) of isobutene to polyisobutene. The results are shown in Table 2.

  Each raw material pretreated with activated alumina has a high conversion rate even when the same amount of catalyst is added, compared to the case where the pretreatment is not carried out and the case where the same treatment is carried out with calcium chloride and molecular sieve. It can be seen that

Claims (5)

Saturation mainly containing 5 to 95% by mass of olefins mainly containing 4 olefins and saturated aliphatic hydrocarbons having 4 carbons, including hydrocarbons obtained from raffinate of extractive distillation method using diene hydrocarbon as an extract A liquid hydrocarbon composed of 95 to 5% by mass of aliphatic hydrocarbons (100% by mass of both) is brought into contact with an inorganic solid treatment agent containing alumina, and then a hydrocarbon-soluble halogen-containing acid catalyst is used. A method for producing an olefin polymer comprising polymerizing a part or all of an olefin in the presence thereof.   The said olefin contains isobutene, The manufacturing method of the olefin polymer of Claim 1 characterized by the above-mentioned. The method for producing an olefin polymer according to claim 2, wherein the halogen-containing acid catalyst is any one of the following formulas (1) and (2).
AlRmXn (1)
(Here, 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 m + n = 3).
Al2RpXq (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.) Process for producing an olefin polymer according to claim 2 or claim 3, wherein the halogen-containing acid catalyst is ethyl aluminum dichloride. The method for producing an olefin polymer according to any one of claims 1 to 4 , wherein the organic solvent used for the extractive distillation is dimethylformamide.