JPH0521126B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a bulk polymerization method using propylene itself as a polymerization medium, or a gas phase polymerization method to obtain polypropylene by polymerizing propylene at least as a catalyst diluent. This invention relates to a method for recovering inert hydrocarbon compounds. BACKGROUND TECHNOLOGY Recent improvements in catalyst performance have provided excellent catalysts, while advances in polymerization methods have led to polymerization methods that do not use inert hydrocarbon compounds as polymerization media, such as bulk polymerization or gas phase polymerization. As a result, processes that use almost no inert hydrocarbon compounds are being developed. Problems to be Solved by the Invention However, although the amount of inert hydrocarbon compound used is extremely small compared to the polypropylene obtained by the above method, the catalyst is Generally, it is diluted with a chemical compound, and inert hydrocarbon compounds are charged to certain parts such as valves to prevent blockages, so a considerable amount of inert hydrocarbon compounds are used. Therefore, in order to save resources, it is desirable to collect and reuse them in a simple manner. Means for Solving the Problems As a result of intensive study on methods for solving the above problems, the present inventor discovered that it is possible to recover inert hydrocarbon compounds that can be reused by distilling them using a specific method. Heading The invention has been completed. That is, the present invention comprises a solid transition metal catalyst containing a titanium halide, an organoaluminum compound, and at least one member selected from esters, ethers, orthoesters, alkoxy silicones, and glycol ethers having a boiling point of 150°C or higher measured at normal pressure. The above polymerization is carried out using a catalyst system consisting of a compound in which propylene itself is used as a medium. In a method of recovering and reusing activated hydrocarbon compounds, inert hydrocarbon compounds are heated at normal pressure while introducing an inert gas using a distillation column that has an inert gas inlet below the condensation section at the top of the distillation column. The boiling point measured at
The present invention relates to a method for recovering a diluent, which is characterized in that it is recovered by distillation as a fraction at 140°C or lower, which does not contain esters, ethers, orthoesters, alkoxy silicones, or glycol ethers at 150°C or higher. In the present invention, the solid transition metal catalyst containing titanium halide is one that contains titanium halide as an active transition metal component, and one that also contains aluminum halide, or magnesium halide, silica, alumina. So-called carrier-type catalysts in which titanium halide is supported on a carrier such as esters, esters, ethers, orthoesters, amines, amides, etc., whose boiling point is 150°C or higher when measured at normal pressure are present. good. In the present invention, the organic aluminum compound is not particularly limited, but preferably trialkylaluminum such as triethylaluminum, tripropylaluminum, triisobutylaluminum, dialkylaluminum monohalide such as diethylaluminum chloride, dipropylaluminum chloride, ethylaluminum Alkylaluminium sesquihalides such as sesquichloride, alkylalkynium dihalides such as ethylaluminum dichloride, or alkylaluminum sulfates can be used. In the present invention, esters, ethers, orthoesters, alkoxy silicones, or glycol ethers having a boiling point of 150°C or higher measured at normal pressure during polymerization are used as stereoregularity improvers or catalyst activity improvers. If the boiling point measured at normal pressure is lower than 150°C, separation from inert hydrocarbon compounds will not be easy, which is undesirable. Specific compounds include monoalkyl esters, dialkyl esters, aromatic ethers or di- or triethylene glycols of aromatic carboxylic acids, diethers or monoalkyl ethers of propylene glycol, aromatic orthoesters, di-, tritetra- Examples include alkoxysilanes. More specifically, esters such as methyl, ethyl, propyl, and butyl of benzoic acid, toluic acid, anisic acid, and naphthylic acid, ethers such as diphenyl ether, dibenzyl ether, and amyl ether, methyl orthobenzoate, and orthobenzoic acid. Ethyl, methyl orthotoluate, ethyl orthotoluate, methyl orthoanisate,
Orthoesters such as ethyl orthoanisate, diethylene glycol dipropyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dipropyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol dimethyl ether Propyl ether, diethylene glycol monoisopropyl ether, triethylene glycol monomethyl ether, triethylene glycol monopropyl ether, tetraethoxysilane, triethoxymethylsilane, phenyltrimethoxysilane,
Examples include phenyltriethoxysilane, diphenyldimethoxysilane, and diphenyldiethoxysilane. In the present invention, the boiling point of the inert hydrocarbon compound at normal pressure is required to be 60 to 140°C,
If it is lower than 60°C, it is not easy to separate it from propylene, and if it is higher than 140°C, it is not easy to separate it from the above-mentioned ester, ether, orthoester, glycol ether or alkoxy silicon. Specific examples of inert hydrocarbon compounds include hexane, heptane, octane, benzene, toluene,
Mention may be made of xylene, ethylbenzene and mixtures thereof. The inert hydrocarbon compounds recovered in the present invention are those used as a diluent for charging the solid transition metal catalyst in the form of a slurry into the polymerization reaction zone;
Examples include those charged with the organoaluminum compound as a diluent for the safety of the organoaluminum compound, or those charged to prevent valves etc. from being blocked by the polymer. The inert hydrocarbon compound used as a diluent for charging the solid transition metal catalyst to the polymerization zone is essential. The polymerization reaction is carried out by a bulk polymerization method using propylene itself as a liquid medium or a gas phase polymerization method in which substantially no liquid medium is present, and the amount of inert hydrocarbon compound used is the monomer or the resulting polymer. The present invention is effective when the amount is extremely small compared to . In other words, if a large amount of inert hydrocarbon compound is used, the polymerization-inhibiting components that are probably generated during polymerization are relatively small and must be separated by distillation into an amount that does not substantially affect catalyst performance. This is because it is relatively easy to do so. In general, inert hydrocarbon compounds include:
Examples include those recovered as high-boiling components from recovered unreacted monomers such as ethylene and propylene, and high-boiling components recovered during drying of polypropylene powder. In order to use these recovered inert hydrocarbon compounds in the production of solid transition metal catalysts or as diluents, it is necessary to rectify them very precisely and separate the inert hydrocarbon compounds. It is necessary to remove a large amount of low-boiling components and high-boiling components using a distillation column with a large number of stages, resulting in a low yield of purified inert hydrocarbon compounds and high purification costs. On the other hand, in the method of the present invention, esters at 150°C or higher,
An inert gas is introduced using a distillation column with a number of stages sufficient to remove ethers, orthoesters, glycol ethers, etc. as high-boiling substances, and an inert gas inlet below the condensation section at the top of the column. By distilling the inert hydrocarbon compound while reusing it, a reusable amount of inert hydrocarbon compound can be recovered and used. Distillation may be carried out either continuously or batchwise, and the number of stages required is usually several. In addition, the inert gas inlet is located below the condensing section, and the above-mentioned esters, ethers, etc.
Orthoesters or glycol ethers (hereinafter referred to as
It is sufficient if the number of stages is above a sufficient number of stages to remove the fraction (150°C or higher). This is because if the number of stages is below a sufficient number to remove the fraction at 150° C. or higher, the fraction at 150° C. or higher will be distilled out along with the inert gas. Examples of the inert gas used in the present invention include nitrogen gas and helium gas. The appropriate flow rate of the inert gas is 1/100 to 1/10 of the volume of the rising vapor flow reaching the condensing section, considering the volume as a gas.If it is less than 1/100, the effect will be insufficient, and if it is more than 1/10, it will not be effective. Inert hydrocarbons to be recovered are entrained in the inert gas, resulting in a decrease in yield, which is undesirable. Effect It is presumed that the method of the present invention effectively removes polymerization-inhibiting components with a relatively low boiling point, so that the diluent can be recovered with simple operations. Examples The present invention will be further explained with reference to Examples below. Example 1 (A) Production of solid transition metal catalyst A vibratory mill equipped with two grinding pots each having an internal volume of 900 ml and containing 80 steel balls with a diameter of 12 mm was prepared.
In this pot, under nitrogen atmosphere, 30 g of magnesium chloride and 3 g of ethyl orthoacetate were added per grinding pot.
ml, 6 ml of 1,2-dichloroethane was added, and the mixture was ground for 40 hours. By repeating this operation twice, 80 g of the pulverized product was brought into contact with 500 ml of titanium tetrachloride in a 2 liter round bottom flask with stirring at 80° C. for 2 hours, and then allowed to stand, and the supernatant liquid was removed. Next, 1 liter of n-heptane was added, stirred at room temperature for 15 minutes, allowed to stand, and the washing operation of removing the supernatant liquid was repeated seven times, followed by an additional 500 ml of n-heptane to obtain a solid transition metal catalyst slurry. (B) (i) Preparation of catalyst slurry: 50 l of n-heptane
A catalyst slurry was prepared by adding 50 g of the above solid transition metal catalyst slurry, 214 ml of diethylaluminum chloride, and 100 ml of methyl toluate. Separately, 133 ml of triethylaluminum was diluted with 20 liters of n-heptane. (ii) Polymerization: In the apparatus shown in Figure 2, A is a polymerization reactor with an internal volume of 500 liters, and the slurry obtained by polymerization in A is sent to autoclave C (inner volume 200 liters) via line 15 and pump B. ,
A portion of the slurry is recycled to A. At C, a catalyst deactivator (diethylene glycol monoisopropyl ether) is added and the slurry is
Most of the medium (propylene and n-heptane) discharged from 6 is separated by cyclone G by heating tube D, and the powder is sent to H for further drying. Drying is carried out by introducing propylene heated to 90°C from 24, and propylene, n-heptane, etc. are sent to heat exchanger F from line 18, 0.1Kg/cm ^2- gauge, 30°C.
The recovered material cooled and liquefied is sent to tank I via line 20. On the other hand, the vapor mainly containing propylene taken out from line 17 is cooled to 0.1 kg/cm ² -gauge in heat exchanger E and 30°C, and the recovered material is liquefied from line 19 to tank I.
sent to. The unliquefied gases are sent to the propylene recovery system via lines 21, 22 and 23, respectively. The following polymerization and n-heptane recovery operations are performed using this apparatus. A catalyst slurry (3 g/hour as a solid catalyst), triethylaluminum (8 ml/hour), and propylene (80 kg/hour) were charged into polymerization reactor A, and polymerization was carried out at 70°C. At this time, n-heptane was charged at a rate of 5 liters/hour for flushing the pump and valves. On the other hand, the polymerization slurry was sent from A to C at a rate of 80 kg/hour, and at C, triethylene glycol monomethyl ether was further sent at a rate of 100 ml/hour to deactivate the catalyst. C
Deactivated slurry was discharged from the dryer H at a rate of 80 kg/hour, powder was removed from the dryer H at a rate of about 30 kg/hour, while liquid was collected into tank I at a rate of 9.6 l/hour. This recovered liquid, mostly consisting of n-heptane, has an inert gas introduction line 1 at the top and a shelf below the inert gas inlet, as shown in Figure 1, and has a number of theoretical plates of 5. Using a stage distillation column, the reflux ratio
1.0, using nitrogen as an inert gas with a rising steam rate of 15 ml/min, and distilling the introduced amount at 50 ml/min until the pot temperature reaches 170°C and the upper part of the distillation column reaches 100°C without removing the low boiling part. The distillate was taken out. No methyl toluate or diethylene glycol monoisopropyl ether was detected in the distilled n-heptane. The yield of the distillate was 90% based on the liquid taken out from Tank I. This recovered heptane is referred to as recovery liquid 1. Further, heptane distilled without introducing nitrogen into the inert gas inlet was used as recovered liquid 2. (C) Using the above recovered liquids 1 and 2, a solid transition metal catalyst was produced in the same manner as in section (A) (however, on a scale of 10 g of pulverized material). (D) Polymerization reaction: Solid transition metal catalyst obtained in (C) and as a comparison
Polymerization was carried out using the material obtained in (A). The polymerization reaction is carried out using a solid transition metal catalyst in an autoclave with an internal volume of 5 liters.
30mg, 0.06ml of methyl toluate, 0.128ml of diethylaluminum chloride, 0.08ml of triethylaluminum, and 50ml of n-heptane for dilution (all using the same n-heptane used in (A)) were mixed and charged, and then 1.5ml of propylene was added. Kg, add 1.5Nl of hydrogen and 75
After polymerizing at ℃ for 2 hours, unreacted propylene was purged and dried under reduced pressure at 60℃ to obtain a powder (20mm
Hg for 6 hours). Example 2 Highly active titanium trichloride TGY- ₂₄ (92% as TiCl3, manufactured by Marubeni Solve A) was used as a solid transition metal catalyst.
Polymerization was carried out using the same apparatus as in Example 1(B) using 8% of high boiling point ether. As the catalyst slurry, 100g of the above titanium trichloride,
Toluene 100l, diethyl aluminum chloride
Mix 800ml, charge 500g of propylene and heat to 40℃.
The mixture was stirred for 1 hour to polymerize 5 g of propylene per 1 g of titanium trichloride. Next, 0.5 ml of diethylene glycol monoisopropyl ether was added to form a catalyst slurry. Polymerization was carried out in the same manner as in Example 1 (B) (ii) except that this catalyst slurry was used as a solid transition metal catalyst at a rate of 7 g/hour and triethylaluminum was not charged, and polymerization was carried out using toluene for flushing the pump and valve. did. Tank I is
Liquid was withdrawn at 12.8 l/hour. The recovered liquid, mostly consisting of toluene, was recovered in the same manner as in Example 1 (B) (ii) and distilled by introducing an inert gas (helium) (recovered liquid 1) and without introducing toluene. (Recovered liquid 2) was obtained. The yields were 86% and 87%, respectively. 100 g/l of titanium trichloride catalyst was added to each recovered toluene, stirred and kept for 20 hours, and the catalyst slurry was used for polymerization. titanium trichloride
100mg, diethyl aluminum chloride 0.8ml,
A catalyst slurry consisting of 100 ml of toluene for dilution (however, all the toluene used in the previous polymerization was used) was charged, and polymerization was carried out in the same manner as in Example 1-(D) using 1.5 kg of propylene, 3 Nl of hydrogen, and 70°C for 3 hours. Got the powder.
The results are shown in the table. Effects As shown in the Examples, by carrying out the method of the present invention, inert hydrocarbon compounds that do not adversely affect catalyst performance can be recovered in good yield, which is industrially valuable. 【table】

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of the position of the inert gas inlet at the top of the distillation column, where 1 is the inert gas inlet, 2 is the line that leads the rising steam to the condenser 3, and 4 is the inert gas inlet. 5 is a condensate reservoir, 6 is a condensate reflux line, and 7 is a distillate distillation line. Figure 2 is a polymerization flow sheet, A...Polymerization tank, B...Pump, C...Deactivation tank, D, E, F
... Heat exchanger, G ... cyclone, H ... dryer, I ... tank, J, J' ... valve, 11 ...
Deactivator charging line, 12... Propylene charging line, 13, 14... Catalyst charging line, 15... Slurry circulation line, 16... Slurry discharge line, 17, 18... Recovery steam line, 19, 20
... Recovery liquid line, 21, 22, 23 ... Uncondensed gas line, 24 ... Dry gas charging line, 25
...Dry powder discharge line.

Claims (1)

[Claims] 1 Consists of a solid transition metal catalyst containing titanium halide, an organoaluminum compound, and at least one compound selected from esters, ethers, orthoesters, alkoxy silicones, and glycol ethers with a boiling point of 150°C or higher measured at normal pressure. The above polymerization is carried out using a polymerization method using propylene itself as a medium using a catalyst system, using at least an inert hydrocarbon compound having a boiling point of 60 to 140 °C as measured at normal pressure as a catalyst diluent, and the inert carbonization is carried out. In a method of recovering and reusing hydrides, inert hydrocarbon compounds are removed at normal pressure while introducing an inert gas using a distillation column that has an inert gas inlet below the condensation section at the top of the distillation column. 1. A method for recovering a diluent, which comprises recovering by distillation separation as a fraction of 140° C. or lower that does not contain esters, ethers, orthoesters, alkoxy silicones, or glycol ethers with a measured boiling point of 150° C. or higher.