JPS61133204A - Reclamation of solvent for ziegler-type polymerization - Google Patents

Abstract

PURPOSE:To accomplish the titled reclamation by hydrogenation treatment, using a transition metal-based hydrogenation catalyst, of solvent used in Ziegler- type polymerization to effect efficient deactivation of the polymerization- inhibiting substances accumulated in the polymerization solvent. CONSTITUTION:A solvent used in Ziegler-type polymerization (e.g., benzene, xylene, 4-20C paraffin) is scrubbed ar distilled if needed, followed by hydrogena tion treatment of the solvent using a transition metal-based hydrogenation catalyst (e.g., titanium trichloride, alkoxyoxyvanadium halide), normally at room temperature-100 deg.C under a hydrogen-pressurized condition of 3-9kgf/cm<2>, thus accomplishing the objective reclamation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for regenerating a polymerization solvent used when producing polyolefins by Ziegler type polymerization. Specifically, after isolating the polymer, if necessary, the polymerization solvent that has been washed with water and purified by distillation is further subjected to a lignification treatment to render harmless polymerization inhibitors accumulated in the polymerization solvent.

(Prior art) Conventionally, in the polymerization of olefins using a Ziegler type catalyst, after olefins are combined in the presence of a catalyst and a solvent, the product is separated and the recovered solvent is recovered either as it is or by distillation. Subjected to polymerization. However, although the cause is not clear, when a recovered solvent is used once or after being dispersed, the catalytic activity may be lower than when a fresh solvent is used, and the physical properties of the resulting polymer may deviate from the target. This is because the solvent contains small amounts of impurities such as polymerization by-products from side reactions between the catalyst and raw olefin, catalyst decomposition products, and decomposition products of various other raw materials, including the solvent itself. it is conceivable that.

(Problems with the prior art) In order to remove these impurities, the solvent is distilled and reused, but it is necessary to keep these impurities below an acceptable level so that they do not affect the polymerization as much as possible. To do this, increase the reflux ratio during distillation.

It is necessary to increase the gut ratio for high and low boiling point components, which increases industrial disadvantages such as an increase in 1M air usage and a deterioration in the solvent consumption rate. Further, even if the above-mentioned distillation was carried out, a decrease in activity could not be avoided when using unagigaeshi.

Recently, the activity of polymerization catalysts has increased significantly, and processes in which the concentration of catalyst in the solvent is significantly reduced have become commonplace. In this case, the upper platform reaction is easily affected by impurities in the raw materials such as olefin 7, which deteriorates the catalyst unit consumption and greatly fluctuates the physical properties of the produced polymer, which greatly impedes the operation of the process. A solution was needed.

(Means for solving the problem) As a result of various studies in order to overcome the drawbacks of the conventional solvent regeneration techniques as described above, the inventors have discovered that after washing the solvent with water and distilling it as necessary, the solvent is further treated with transition metal hydrogen. The present invention was completed by discovering that wood can be efficiently regenerated by wood conversion treatment using a chemical catalyst.

The solvent regeneration method of the present invention is usually carried out by distilling the solvent from which the polymerization product has been separated and then treating it with wood.

It is also possible to directly hydrogenate the polymerization product after separation.

As the catalyst for the lignification treatment of the present invention, both a supported transition metal catalyst and a transition metal mixed molded catalyst can be used, and the transition metals include FeCo, Ni, Ru, Rh, and P.
Examples include d, Ir, PL, and the like. Salts such as oxides and complexes of these metals can also be used as catalysts. It can also be used as a carrier for transition metal-supported hydrogenation catalysts.

Activated carbon, graphite, glue, silica alumina, alumina, etc. can be used, and diatomaceous earth etc. can be used as the molding material for the 1,11 transfer metal mixed molded catalyst.

The supporting (mixing) ratio of the transition metal or its oxide or salt on the carrier or molding material is not particularly limited, and may be within the range used in ordinary hydrogenation reactions.

The hydrogenation reaction of the present invention is a batch, continuous liquid phase.

It can be carried out in either a gas phase or a gas-liquid mixed phase system, and the method of contact with the catalyst can be slurry, fixed bed, or fluidized bed.The shape of the reactor can be seed type, tube type, base type, etc. ,
Those used in ordinary hydrogenation reactions can be used. Hydrogenation reaction 1 conditions vary depending on the reaction type, but normal pressure to 30 kgf/cm', preferably 3 to 9 kg
f/cm? under hydrogen pressure, temperature 0~150℃,
Preferably, the reaction time per reaction time is from room temperature to 100° C. 0.1 to 120 minutes, preferably 10 minutes to 60 minutes in the case of a batch method, and preferably 0.5 to 20 minutes in average residence time in the case of a continuous method. The olefin concentration in the solvent, including unreacted raw material monomers, reaction by-products, etc., is determined by the bromine index (mg-Br, 710
0g-solvent)-C'200-4000, preferably 20
The concentration of reaction by-products in the system is usually 0 to 2000, expressed as a bromine index of 0 to 200. The amount of hydrogenation catalyst used varies depending on the type of gas reaction, woody reaction type, residual olefin, etc., but generally it is within the range used for hydrogenation reactions. Examples of the polymerization solvent include hydrocarbons that are normally used to dissolve or disperse the polymer or catalyst produced during the polymerization of olefins, such as paraffins having about 4 to 20 carbon atoms, cycloparaffins, Hensen, toluene, The olefin polymerization reaction carried out in the present invention includes xylene and mixtures of two or more thereof.
~ So-called Ziegler-5! carried out using a combination catalyst consisting of an organometallic compound of Group 3 metal and, if necessary, an electron donor compound! It is a polymerization reaction.

The above transition metal compounds include titanium, vanadium,
Examples of zirconium compounds used include titanium trichloride, titanium tetrachloride, tetraalkoxytitanium, vanadium tetrachloride, vanadium trichloride, alkoxyoxyvanadium oxide, zirconium trichloride, and dialkylzirconium halides.

Furthermore, when using a highly active catalyst in which these transition metal compounds are supported on a carrier such as magnesium chloride, the effects of the present invention are particularly significant.

The highly active catalyst supported on the above carrier includes a carrier such as magnesium chloride or magnesium oxide, a transition metal compound such as titanium tetrachloride, tetraalkoxytitanium, or vanadium tetrachloride, and, if necessary, an organic acid ester, an organic silicon compound, A component in which an electron-donating compound such as an alkyl halide is supported by a known method is used.

Examples of the above-mentioned organometallic compounds include organoaluminum compounds such as trialkyl aluminum, dialkyl aluminum halide, flukylaluminum sesquihalide, and alkyl aluminum civalide; organomagnesium compounds such as dialkyl magnesium; Examples include ethylaluminum sesquichloride and diethylmagnesium, and mixtures thereof may be used.

In addition to the above transition metal compounds and organometallic compounds, esters, amines, and ethers are used to improve the activity of the catalyst and control the physical properties of the produced polymer.

Electron donating mixtures such as haloflucans can also be added.

In addition, as the olefin used in the above polymerization reaction,
Ethylene, phlopylene, 1-butene, l-hexene,
There are α-olefins such as l-octene, 1-dodecene, and 4-methylthopentene, and the solvent regeneration method of the present invention involves copolymerization reactions of these or further copolymerization of these with butadiene,
It can also be applied to copolymerization reactions with dienes such as isoprene, dicyclopentadiene, and ethylidene norbornene. There are no particular limitations on the polymerization conditions such as temperature, pressure for 1 hour, concentration of reactants, etc., and the polymerization can be carried out under known conditions.

The present invention will be explained in more detail below using Examples.

(Examples 1 to 6) The hydrogenation catalyst shown in Table 1 was heated to 110°C or higher for about 1 hour in a nitrogen atmosphere to remove adsorbed moisture, oxygen, etc., and then passed through hydrogen diluted with nitrogen for reduction. Treatment (Pt, Pa
60-110°C for catalyst, 1 hour - 210°C for Ni catalyst.

4 to 8 hours).

After polymerization, the resulting polymer is separated using the method described below.

The water-washed isohexane is washed with water and refluxed using a two-stage 2.0-stage core distillation column. The recovered hexane (1) was obtained by dehydrating the obtained isohexane by nitrogen bubbling.

1.5 kg of the recovered hexane (1) was placed in a T and ST glass autoclave, and after purging the autoclave with nitrogen, 40rnfL of the hydrogenation catalyst after the above reduction treatment was charged, the mixture was sealed, and the temperature was raised to 50°C. Next, hydrogen was charged to 5 kg/cm2G and hydrogenated for 30 minutes while stirring at 500 rpm. After cooling the reaction solution temperature to room temperature, the pressure was depressurized, and the hydrogenation catalyst was removed by scraping under a nitrogen atmosphere. Hexane was designated as hydrogenated hexane (1).

480 m of the obtained hydrogenated hexane (1) was placed in a flask 11 equipped with a condenser and a stirring device, and vanadium oxytrichloride (O, Lmmoi) was added under nitrogen bubbling, and nitrogen gas was added to ethylene while stirring at 2000 rpm. - Switched to propylene mixed gas (volume ratio = 40760) at 100 m/h. While maintaining the liquid temperature at 35°C, the monomer gas charging rate was increased to 400 m/h, and a solution prepared in advance by dissolving 1 mmoi of ethylaluminum sesquichloride in 20 ml of hydrogenated hexane (1) was quickly added. The dropping gas was charged at a rate of 100~
Copolymerization was carried out at a blowing temperature of 35° C. for 10 minutes while adjusting the supply rate within the range of 400 m/h to avoid insufficient supply. 1m
After adding methanol (i) to stop the copolymerization reaction,
After adding a large amount of methanol to precipitate, the mixture was dried under reduced pressure to obtain ethylene-propylene copolymers having the same properties as those obtained using fresh isohexane solvent in the yields shown in Table 1.

Further, a copolymerization reaction of propylene and 1-butene was carried out as follows.

[I] Preparation of highly active Ti catalyst component (2) Using a stainless steel ball mill, 20 g of anhydrous magnesium chloride and 4. ethyl benzoate were added under a nitrogen atmosphere.
8 g was added and co-pulverized for 24 hours. 15 g of the above carrier was placed in a 200 m round-bottomed flask under a nitrogen atmosphere, and 150 ml of titanium tetrachloride was first added dropwise at room temperature. Temperature 80℃
After stirring for 2 hours, the supernatant was removed by decantation and 7100 m of Nihex was added. After stirring, the process of removing the supernatant by decantation was repeated 5 times. When this component, n-hexane, was evaporated and analyzed, it was found that 1.3 wt% of Ti was contained.

[11] Propylene-butene copolymerization (Examples 1 to 6)
500 mJL of hydrogenated hexane (L) prepared in ) was placed in a one-size flask equipped with a condenser and a stirring device, 1 mmoi of triethylaluminum was added under nitrogen bubbling, and then 0.33 mmoi of benzoinated ethyl was added.
Nitrogen gas was added to propylene while stirring at 1500 rpm.
1-Butene mixed gas (volume ratio = 65/35) 150 views/
I switched to h. While maintaining the liquid temperature at 40° C., 0.01 mm of TiX was added to the Ti catalyst component prepared in [1] and copolymerized for 30 minutes. After stopping the copolymerization reaction by adding 1mM of methanol, a large amount of methanol was added to precipitate it, and it was dried under reduced pressure to produce propylene with the same properties as when used on fresh isohexane solvent.
A butene copolymer was obtained in the yield shown in Table 1. In addition, a polymerization reaction was similarly carried out under the conditions shown in Comparative Example.

(Leaving space below) (Example 7) [1] Preparation of highly active Ti catalyst component (■) In a 300 m diameter round bottom flask under a nitrogen atmosphere, add n-hexane roomi and 5 g of anhydrous magnesium chloride, and stir at room temperature. 18.7 mJL of ethanol, 15 ml of diethylaluminum chloride, and 31.2 mA of titanium tetrachloride were added dropwise in this order. After that, the supernatant liquid was removed by decanting, and 100 ml of n-hexane was added.

After stirring, remove the supernatant liquid by decantation.
Repeatedly. When this component, n-hexane, was evaporated and analyzed, it was found that Ti was contained in an amount of 5.0 L%.

[11] Adjustment of recovered hexane 12 n-hexane, [
N 2mall, Ti component (based on Ti) 0.0
2 mmol,) ethylaluminum CAI group m) 1
$sen 50m9 to mmoJ1 and 1-. After charging in a nitrogen atmosphere, hydrogen was charged at a gas phase partial pressure of 0.5 kg/cm2FF:
Then, charge ethylene to reduce the total pressure to 2.5 kg/am.
Polymerization was carried out at , 70° C. for 2 hours. after that,
- was separated from the produced poly, and the present sample was distilled to n- using a 20-stage distillation column at a flow ratio of 2 to collect a fraction at a temperature of 65 to 67°C. This hexane was designated as 匡souΣ王ヱZ(2), and 2000 wtppm of 1-hexene was present in this hexane. The above recovered hexane was subjected to the lignification treatment described in Example 1, and the hexane was used as Z(2), and the 1-hexene in this hexane was reduced to 30 wtppm. .

゛Hydrogenated hexane (2 pieces) is added to the 2-piece crepe made of corrosion-resistant steel.
) 1 sentence, [I] Adjusted Ti component (■0.02m
moi, after charging 1 mm'ojL of triethylaluminum in a nitrogen atmosphere, hydrogen was added at a gas phase partial pressure of 2.0 kg/cm.
Pressure-fit, then charge ethylene to bring the total pressure to 4 kg/cm2.
As a result of polymerization at 70° C. for 2 hours, powdered polyethylene (1178 g) was obtained, which had the same physical properties as those obtained in the same polymerization using fresh n-hexane.

(Comparative Examples 1 to 5) Using fresh isohexane, recovered hexane (1), and recovered hexane (1) that had been adsorbed and purified as solvents, polymerization was carried out in the same manner as in Example 1. Example) The stated results were obtained. As is clear from this table,
If a solvent that has not been subjected to lignification treatment is used, the yields of both ethylene-propylene copolymer and propylene-1-butene copolymer will be significantly reduced, and the physical properties will also vary.

This decrease in yield is particularly significant in propylene-1-butene copolymerization using a highly active Ti catalyst component.

(Comparative Example 6) Using recovered hexane (2) in place of hydrogenated hexane (2) in Example 7, a polymerization reaction was carried out in the same manner as in Example 7, yielding 176 g of powdered polyethylene. I got it.

(Comparative Example 7) In place of hydrogenated hexane (2) in Example 7, unused n-
A polymerization reaction was carried out in the same manner as in Example 7 using hexane, and powdered polyethylene was obtained in a yield of 170 g.

Table 2 shows a comparison of the results of Example 7 and Comparative Examples 6 and 7. From this table, it can be seen that when recovered-xane (2) is used, the MI, 7M I 2.16 of the produced polymer decreases, but a copolymer with the same physical properties as when hydrogenated hexane (2) is used is obtained. It turns out that you can get it.

Table 2 Tree 1. The ratio of MI at 15 kg and 2.16 kg (effect of the invention) In the method of the present invention, the polymerization-inhibiting components in the solvent are completely converted into harmless substances by the hydrogenation reaction. If recycled by this method, the solvent can be used repeatedly without reducing the yield or physical properties of the single polymer.

Claims (1)

[Claims] A method for regenerating a polymerization solvent, which comprises treating the solvent used in Ziegler-type polymerization with water washing, distillation, etc. as necessary, and then subjecting it to lignification treatment using a transition metal-based hydrogenation catalyst.