JPH0333165B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for gas phase polymerization of olefins using a fluidized bed. In more detail, the fine powder polymer entrained in the gas discharged from the upper part of the fluidized bed is returned to the fluidized bed polymerization reactor without problems such as adhesion or clogging, allowing smooth polymerization to continue for a long period of time. Relating to a phase polymerization method.

In the present invention, the term "polymerization" is sometimes used to include not only homopolymerization but also copolymerization, and the term "polymer" is sometimes used to include not only homopolymers but also copolymers.

As a result of improvements in transition metal catalyst components for olefin polymerization, the production capacity of olefin polymers per unit transition metal has been dramatically increased, and as a result, we have reached a stage where the catalyst removal operation after polymerization can be omitted.
When using such a highly active catalyst, a method of carrying out olefin polymerization in the gas phase is attracting attention because it is the simplest to operate after polymerization.

When carrying out the gas phase polymerization, in order to proceed smoothly with the polymerization, a complete mixing type polymerization vessel such as a fluidized bed polymerization vessel or a stirred fluidized bed polymerization vessel is used, and a catalyst containing gas is added to the olefin-containing gas. A method in which polymerization is carried out while floating and fluidizing an olefin polymer has been widely used.

In this method, it is preferable to recycle and reuse the unreacted gas stream leaving the fluidized bed, and for this purpose, the unreacted gas stream is circulated through a cooler, a circulating gas blower, etc. The finely powdered polymer containing the catalyst, which is discharged along with the gas flow, polymerizes inside these devices and piping.
This can cause lumps to form, causing problems such as reduced equipment performance and blockage.

To avoid such troubles,
Generally, when the unreacted gas leaving the fluidized bed gas phase polymerization zone is recycled and used, it is preferable to introduce the unreacted gas flow into a cyclone in advance to remove the finely powdered polymer. The finely powdered polymer is circulated to the gas phase polymerization zone as soon as possible to prevent problems such as wall adhesion and pipe clogging due to undesired progress of polymerization around the cyclone. That is essential.

Hitherto, the method of circulating such a finely powdered polymer from a cyclone to a gas phase polymerization zone has not been studied in detail. In general, as a method for collecting fine powder discharged from the upper part of the fluidized bed in a cyclone and returning it to the fluidized bed, there is a method in which the fine powder is returned from the vessel wall in the space above the fluidized bed, or a method in which it is returned from the vessel wall in the fluidized bed forming part. When the former method is adopted in the gas phase polymerization of olefins, the amount of fine powder circulated becomes extremely large, making it easy to form lumps around the cyclone, which tends to cause problems such as blockage. Furthermore, when the latter method is adopted, the formation of lumps due to agglomeration of fine powder within the fluidized bed is observed, causing problems such as clogging of perforated plates and the like.

Since the finely divided polymer usually contains a highly active catalyst, it is uneconomical to dispose of it, and it is desirable to recycle it to the fluidized bed polymerizer for reuse. Therefore, the present inventors investigated a method for circulating finely powdered polymer that would avoid the above-mentioned troubles and would not hinder long-term continuous operation. I came to the conclusion.

That is, the present invention provides a method for gas-phase polymerizing olefin using a fluidized bed polymerizer, in which a fine powder polymer-containing gas discharged from the upper part of the fluidized bed is guided to a cyclone to collect the collected fine powder polymer. The present invention relates to a method for vapor phase polymerization of olefin, which is characterized in that gas is supplied to a gas blowing space below a gas distribution plate of a layer polymerizer.

In the gas phase polymerization of the present invention, it is preferable to use a catalyst formed from a transition metal catalyst component and an organometallic compound catalyst component of a metal from Group 1 to Group 3 of the periodic table.

The transition metal compound catalyst component is a compound of a transition metal such as titanium, vanadium, chromium, zirconium, etc., and may be liquid or solid under the conditions of use. These do not need to be a single compound, and may be supported on other compounds or mixed. Furthermore, it may be a complex compound or a composite compound with other compounds.

Suitable transition metal compound catalyst components include transition metal 1
A titanium catalyst component highly activated by a magnesium compound is exemplified as a representative example of a highly active component capable of producing about 5,000 g or more, particularly about 8,000 g or more of olefin polymer per mmol. Can be done. For example, titanium,
A solid titanium catalyst component containing magnesium and halogen as essential components, containing amorphous magnesium halide, and its specific surface area is:
Preferably about 40 m ² /g or more, particularly preferably about 40 m 2 /g or more
80 to about 800 m ² /g can be exemplified. and electron donors, such as organic acid esters, silicic acid esters, acid halides, acid anhydrides, ketones, acid amides, tertiary amines, inorganic acid esters,
It may contain phosphoric acid ester, phosphorous acid ester, ether, etc. This catalyst component contains, for example, about 0.5 to about 10% by weight of titanium, especially about 1 to about 8% by weight, and the titanium/magnesium (atomic ratio) is about 1/2 to about 1/100, especially about 1/2. 3 to about 1/50, halogen/titanium (atomic ratio) from about 4 to about 100, especially about 6 to about 80, electron donor/titanium (molar ratio) from 0 to about 10, especially 0 to about 6. Preferably the one in Many of these catalyst components have already been proposed and are widely known.

The organometallic compound catalyst component is an organometallic compound having a bond between a metal of Groups 1 to 3 of the periodic table and carbon, and specific examples include organic compounds of alkali metals and organic compounds of alkaline earth metals. Examples include metal compounds, organoaluminum compounds, etc., such as alkyl lithium, aryl sodium, alkyl magnesium halide, aryl magnesium halide, alkyl magnesium hydride, trialkyl aluminum, alkyl aluminum halide, alkyl aluminum hydride, alkyl aluminum alkoxide, alkyl lithium aluminum , and mixtures thereof.

In addition to the above two components, for the purpose of adjusting stereoregularity, molecular weight, molecular weight distribution, etc., hydrogen, halogenated hydrocarbons, electron donor catalyst components, such as organic acid esters, silicate esters, carboxylic acid halides, carboxylic acids amides, tertiary amines, acid anhydrides,
Ethers, ketones, aldehydes, etc. may be used in combination. During polymerization, the electron donor component may be used after forming a complex compound (or addition compound) with the organometallic compound catalyst component in advance, or may be used with other compounds such as Lewis acids such as aluminum trihalides. It may be used in the form of a complex compound (or addition compound).

In the method of the present invention, the olefins used for polymerization include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, 3
-Methyl-1-pentene, styrene, butadiene, isoprene, 1,4-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, etc.; homopolymerization or copolymerization of these is possible to the extent that gas phase polymerization is possible. Can be combined.

The method of the present invention can be preferably used for homopolymerization of ethylene or propylene, copolymerization of ethylene and other olefins, and copolymerization of propylene and other olefins.

Gas phase polymerization is carried out in a polymerization vessel using a fluidized bed, such as a fluidized bed polymerization vessel, a stirred fluidized bed polymerization vessel, and the like. The polymerization temperature is below the melting point of the olefin polymer,
The temperature is preferably about 10°C or more lower than the melting point, and from room temperature to about 130°C, particularly about 40 to 110°C. In addition, the polymerization pressure may be, for example, atmospheric pressure to about
A range of 150 Kg/cm ² , particularly from about 2 to about 70 Kg/cm ² is preferred. Hydrogen optionally used in the polymerization is preferably used in an amount of, for example, about 0.001 to about 20 mol, particularly about 0.02 to about 10 mol, per 1 mol of olefin. Furthermore, in order to remove the heat of polymerization, a liquid easily volatile hydrocarbon such as propane or butane may be supplied and vaporized in the polymerization zone.

When using a transition metal compound catalyst component, an organometallic compound catalyst component, an electron donor catalyst component, etc. as described above, the amount of the transition metal compound catalyst component is about 0.0005 to 0.0005 to 1,000,000 in terms of transition metal atoms per 1 volume of the reaction bed. about 1 mmol, especially about 0.001 to about 0.5
millimoles of the organometallic compound catalyst component to the metal/
It is preferable to use the transition metal (atomic ratio) in a proportion of about 1 to about 2000, particularly about 1 to about 500. In addition, the electron donor catalyst component is added in an amount of 0 to about 1 mol per 1 mol of the organometallic compound catalyst component.
In particular, it is preferable to use it in a proportion of about 0 to about 0.5 mol.

The polymerization of olefins is preferably carried out substantially continuously. That is, a method is adopted in which the catalyst component, olefin, hydrogen, diluent, etc. are continuously supplied to the polymerization vessel as necessary, and the polymerization is carried out while the polymer containing the catalyst is floated and fluidized by the gas component. is industrially advantageous. In continuous polymerization,
The polymer was continuously (or intermittently) withdrawn from the polymerization vessel so as to maintain the amount of polymer in the polymerization vessel approximately constant, while passing through a floating flow zone of the polymer, which was the substantial polymerization zone. An unreacted gas stream (optionally containing hydrogen, diluent, etc.) is substantially continuously discharged from the polymerization zone, entraining the finely divided polymer. This is led to a cyclone to collect the finely divided polymer in the unreacted gas stream. The unreacted gas from which the finely divided polymer has been removed can be appropriately passed through various devices such as a cooler and a blower, and then circulated to the polymerization zone for reuse.

In the method of the present invention, it is desirable that the finely divided polymer collected in the cyclone be circulated to the gas phase polymerization zone as quickly as possible so as not to cause problems such as adhesion to the vessel wall or clogging. For this purpose, it is possible to circulate by gravity, but there are also methods using a rotary valve, a method using a fan, etc.
It is desirable to adopt a method of forced circulation, such as by introducing an entrained gas.

During this circulation, in the present invention, circulation is performed in the gas blowing space below the gas distribution plate of the fluidized bed polymerizer. The circulated fine powder polymer is returned to the fluidized bed along with gas such as olefin through the gas distribution plate, but it is not returned locally to a part of the fluidized bed, but evenly through the gas distribution plate. Since it is returned, the flow state is not disturbed and a good flow state can be obtained. Furthermore, since it is circulated from the bottom of the fluidized bed, as polymerization progresses in the fluidized bed, fine powder polymer particles grow, their particle size increases, and are entrained in the exhaust gas from the top of the fluidized bed again. Since the amount of cyclone is reduced, the load on the cyclone is reduced, and troubles such as polymer adhesion around the cyclone are reduced or avoided.

On the other hand, it is desirable that the fine powder polymer returned to the gas blowing space be kept there for as short a period of time as possible and quickly returned to the fluidized bed. For this purpose, it is desirable that the shapes of the gas blowing space and the gas distribution plate be designed to be convenient for the circulation of the finely powdered polymer.

FIG. 1 is a schematic diagram of the vicinity of the fluidized bed polymerizer 1, in which a catalyst is supplied from a tube 9, and olefin and other gas raw materials are supplied from a tube 8 to the fluidized bed polymerizer. The olefin passes through the gas distribution plate 3 and is consumed in polymerization while causing the polymer to float and flow in the fluidized bed. The unreacted gas components are transferred to the fluidized bed polymerizer 1 along with the finely powdered polymer.
It is discharged from the top and led through pipe 5 to cyclone 2. The finely powdered polymer collected by the cyclone 2 is returned to the gas blowing space formed at the bottom of the gas distribution plate 3 of the fluidized bed polymerizer 1 through the blower 10, and is mixed with the gas such as olefin supplied from the bottom of the polymerizer. The gas is then circulated through the gas distribution plate to the fluidized bed and used effectively. After the exhaust gas exiting the cyclone 2 is appropriately disposed of, it can be returned to the pipe 8 and used for circulation. The polymer in the fluidized bed is discharged from pipe 12 through valve 11 so that its height remains approximately constant.

In FIG. 1, in order to prevent the fine powder polymer returned to the polymerization vessel from remaining in the gas injection space more than necessary, the slope α of the polymerization vessel wall forming the gas injection space is preferably at least 45 degrees. 60 to 80
It is hoped that the degree of If this inclination is too gentle, fine powder polymer tends to accumulate on the walls of the polymerization vessel, and there is a risk that the polymer may adhere to the walls of the vessel or form lumps.

Furthermore, in order to allow the finely powdered polymer to pass through the gas distribution plate as quickly as possible, the pore diameter of the gas distribution plate is made larger overall, or the bottom part is widened toward the bottom, so that the polymer can flow easily. It is desirable to be able to return to the layer. For example, for this purpose, it is desirable that the hole diameter of the dispersion plate be at least 5 mm, particularly about 8 to 30 mm, on the gas inlet side.

According to the present invention, there are no troubles surrounding the cyclone, the polymerization condition is good, and it is possible to carry out continuous polymerization for a long period of time.

[Brief explanation of drawings]

FIG. 1 is a drawing showing one embodiment of the present invention.

Claims (1)

[Claims] 1. In a method for vapor phase polymerizing olefin using a fluidized bed polymerizer, a fine powder polymer-containing gas discharged from the upper part of the fluidized bed is guided to a cyclone to collect the collected fine powder polymer. , a gas phase polymerization method for olefin, characterized in that the gas is supplied to a gas blowing space below a gas distribution plate of a fluidized bed polymerizer. 2. The method according to claim 1, characterized in that the wall portion of the polymerizer forming the gas blowing space below the gas distribution plate of the fluidized bed polymerizer has an inclination of at least 45 degrees. 3. The method according to claim 1, wherein the hole diameter on the gas inlet side of the lower part of the gas distribution plate is at least 5 mm.