JPS59126406A - Vapor-phase polymerization of olefin - Google Patents

Abstract

PURPOSE:Fine particles of the polymer which are accompanied by the gas exhausted from the upper part of the fluidized bed are allowed to return to the fluidized bed polymerizer to enable the long-term, smooth operation of continuous, gas-phase olefin polymerization to be carried out. CONSTITUTION:The gas containing fine particles of the polymer, which is exhausted from the upper part of the fluidized bed 4 is introduced into the cyclone 8 where the particles are collected and recycled through the pipe 12 to the fluidized bed polymerizer 3. The circulation is effected to the inside of the fluidized bed more than 10mm. from the wall surface of the polymerizer 3, more than 50mm. from the fluidized bed bottom and less than 4/5H (the height of the fluidized bed). In the meantime, the polymer is taken out from the control valve 14 through the pipe 15 so that the height of the fluidized bed H is kept almost constant. Thus, the long-term, smooth operation of continuous gas-phase polymerization of olefin becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process 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 blockage, and the olefin gas can be used to continuously perform smooth polymerization operations 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 "polymer" is sometimes used to include not only homopolymers but also copolymers.

By improving transition metal catalyst components for olefin polymerization,
As a result of the dramatic increase in the production capacity of olefin polymers per transition metal, we have reached a stage where it is possible to omit the catalyst removal operation after polymerization.

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.

During the gas phase polymerization, a complete mixing type polymerization vessel such as a fluidized bed polymerization vessel or an agitated fluidized bed polymerization vessel is used in order to proceed with the polymerization smoothly. A method of carrying out polymerization while floating and fluidizing the olefin polymer contained therein has been widely praised.

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. Finely powdered polymer containing catalyst, which is discharged along with the gas flow, polymerizes in these devices and piping, forming lumps, which can cause problems such as reduced equipment performance and blockages. becomes.

In order to avoid such troubles, in general, when the unreacted gas leaving the fluidized bed gas phase polymerization zone is recycled, the unreacted gas flow is guided into a cyclone in advance to form a finely powdered polymer. It is preferable to remove the finely divided polymer, and the fine powder polymer thus collected is circulated to the gas phase polymerization zone as soon as possible to prevent undesirable progress of polymerization around the cyclone, such as wall adhesion and pipe clogging. It is important to prevent problems from occurring.

Conventionally, a method of circulating such a finely powdered polymer from a cyclone to a gas phase polymerization zone has not been studied in detail. Generally, the fine powder discharged from the upper part of the fluidized bed is collected in a cyclone and returned to the fluidized bed by returning it from the vessel wall in the space above the fluidized bed or from the vessel wall in the fluidized bed forming part. . When the former method is employed 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. Further, when the latter method is adopted, formation of lumps due to agglomeration of fine powder is observed in the fluidized bed, and troubles such as pore removal and blockage occur.

Since the finely divided polymer usually contains a highly active catalyst, it is uneconomical to discard it, and it is desirable to recycle it to the fluidized bed polymerization vessel for reuse. Therefore, the present inventors investigated a method for circulating fine powder polymer that would avoid the above-mentioned troubles and would not hinder long-term continuous operation, and as a result, they found a method for circulating it to a specific position within the fluidized bed. It's arrived.

That is, the present invention is a method for gas phase polymerization of olefin using a fluidized bed, in which a gas containing a finely divided polymer discharged from the upper part of the fluidized bed is guided to a cyclone, and the collected finely divided polymer is transferred to a fluidized bed polymerization vessel. A method for vapor phase polymerization of olefins, characterized in that the circulation is carried out at a position inside the fluidized bed at least 1 Qmm from the wall of the polymerization vessel, 5Qmm or more from the bottom of the fluidized bed, and 415 or less above the height of the fluidized bed. be.

In the gas phase polymerization of the present invention, it is preferable to use a catalyst formed from a catalytic metal catalyst component and an organometallic compound catalyst component of a metal from Group 1 to Group 6 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 in a liquid or solid state 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.

A suitable transition metal compound catalyst component is 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 of transition metal, and a typical example thereof is a highly active component that can be produced by a magnacilam compound. An example of this is a titanium catalyst component. For example, a solid titanium catalyst component containing titanium 1 magnesium and a halogen as essential components, containing amorphous magnesium halide, and having a specific surface area of preferably about 40 m2/g or more, particularly preferably A component of about 80 to about 800 m/g can be exemplified. and electron donors such as organic acid esters, silicate esters, acid halides, acid anhydrides, ketones, acid amides,
It may also contain tertiary amines, inorganic acid esters, phosphate esters, phosphite esters, ethers, and the like. 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 from about 1 to about 1150, halogen/titanium (atomic ratio) from about 4 to about 100, especially from about 6 to about 80, and nine electron donor/titanium (molar ratio) from 0 to about 10.
, particularly those in the range of 0 to about 6 are preferred.

Many of these catalyst components have already been proposed and are widely known.

The organometallic compound catalyst component belongs to Groups 1 to 3 of the periodic table.
Specific examples include organic compounds of alkali metals, organic metal compounds of alkaline earth metals, and organic aluminum compounds, such as alkyl lithium, Aryl sodium, alkylmagnesium, arylmagnesium, alkylmagnesium halide, arylmagnesium halide, alkylmagnesium hydride,
Trialkylaluminum, alkylaluminum halide, alkylaluminum hydride, alkylaluminum alkyl J oxide hair alkyl lithium aluminum,
Examples include mixtures of these.

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, ketone hairdehydes, 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, 6-methyl-1 -Pentene, styrene, butadiene, isoprene, 1,4-hexadiene 1. Examples include dicyclopentadiene, 5-ethylidene-2-norbornene, etc., and homopolymerization or copolymerization of these can be performed within a range where gas phase polymerization is possible.

The method of the present invention can be suitably 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, an agitated fluidized bed polymerization vessel, and the like.

The polymerization temperature is below the melting point of the olefin polymer, preferably about 10°C or more lower than the melting point, and from room temperature to about 130°C.
°C1, particularly about 40 to 110 °C. Further, the polymerization pressure is, for example, atmospheric pressure to about 150 kg.
/otr2, especially about 2 to about 70 kq 101
A range of 12 is preferred. Hydrogen optionally used in the polymerization is preferably used in an amount of, for example, about 0.001 to about 20 moles, particularly about 0.02 to about 10 moles, per mole of olefin. In order to remove the heat of polymerization, a liquid easily volatile hydrocarbon such as propane or putaj 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 approximately 0.00% in terms of transition metal atoms per 14 reaction bed volumes. 0005 to about 1 mmol, especially about o, o o i to about 0.5 mmol,
The organometallic compound catalyst component has a metal/transition metal (atomic ratio) of about 1 to about 2000, particularly about 1 to about 500.
It is preferable to use the ratio such that In addition, the electron donor catalyst component was added to 0% per mole of the organometallic compound catalyst component.
It is preferably used in a proportion of O to about 1 mol, particularly O to about 0.5 mol.

The polymerization of olefins is preferably carried out substantially continuously.

i.e. catalyst components, olefin, optionally hydrogen,
It is industrially advantageous to adopt a method in which a diluent and the like are continuously supplied to a polymerization vessel and polymerization is carried out while the catalyst-containing polymer is suspended and fluidized by a gas component. In continuous polymerization, the polymer is continuously (or intermittently) withdrawn from the polymerization vessel so as to maintain the amount of polymer in the polymerization vessel almost constant, while the polymer is suspended in a substantial polymerization zone. The unreacted gas stream (optionally containing hydrogen, diluent, etc.) passing through the flow zone 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 fine powder 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 preferable that the finely powdered polymer collected in the cyclone be circulated to the gas phase polymerization zone as quickly as possible so as not to cause troubles such as adhesion to the vessel wall or clogging. For this purpose, it is possible to circulate by natural fall, but it is preferable to adopt a method of forced circulation using a method using a rotary valve, a method using a fan, a method by introducing entrained gas, etc. In particular, it is preferable to use a fan. During this circulation, in the present invention, for example, the height of the fluidized bed is 300 to 12000 mm,
When performing gas phase polymerization of olefin while forming a fluidized bed with a diameter of about 500 to 6000 mm,
Position the circulation at the bottom of the fluidized bed (usually the top of the gas distribution plate).
at least 5 Qmm above the fluidized bed height H), but at least 415 mm below the fluidized bed height H), preferably 1 Qmm from the bottom of the fluidized bed.
The height is 15H to 2/3H, and the position is 10 mm or more, preferably 5Q mm or more away from the side wall surface of the polymerization vessel. If the circulation position is moved closer to the bottom of the fluidized bed than the above position, problems such as uneven flow of the circulating gas and stagnation of the polymer will occur, which will significantly impede the flow state directly above the bottom of the fluidized bed and cause the formation of lumps. cause.

In addition, when the circulation position is moved higher than the above position, the fine powder polymer that has been circulated in the polymerization vessel immediately passes through the polymerization zone and is guided again to the cyclone together with the unreacted gas. This means repeating so-called short passes. Since the residence time of the finely divided polymer in the polymerization vessel is short, not only does growth not progress, but the load on the cyclone increases, causing problems such as adhesion to the vessel wall and blockage. In addition, if the circulation position is moved closer to the side wall of the polymerization vessel than the above position, the normally smooth downward flow of polymer near the wall will be disrupted, creating a stagnation area of the polymer. This tends to cause troubles such as lump formation.

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

In the fluidized bed polymerizer 6, a fluidized bed 4 is formed above a perforated plate 6. A catalyst suspension obtained by prepolymerizing a transition metal compound catalyst component and an organometallic compound catalyst component with a small amount of olefin in a separate container is passed from a tube 1 to a heater 2 to vaporize the liquid medium. Polymerization vessel 6
supply to. The raw material olefin, hydrogen and diluent used as necessary are supplied to the polymerization reactor either freshly or by circulation through the tubes 5 and Vll, and the polymerization reaction is carried out while fluidizing the fluidized bed 4. The unreacted gas that has passed through the fluidized bed is
After the fine powder polymer is discharged from the pipe 7, it is led to a cyclone 8 to remove the powder polymer. The unreacted gas from which the finely divided polymer has been removed is circulated from pipe 11 through cooler 16 and circulation blower 16 to the polymerization vessel. A fan 9 provided at the bottom of the cyclone 8 forces the finely powdered polymer in the cyclone to circulate through the tube 12 into the fluidized bed.

The nozzle tip position in the fluidized bed of the tube 12 is away from the side wall by d1 upward from the perforated plate 6 by h, which is the fluidized bed height). On the other hand, the polymer is withdrawn from the control valve 14 through the pipe 15 so that the height of the fluidized bed remains approximately constant.

According to the above embodiment, gas phase polymerization of olefins could be carried out continuously and smoothly over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a drawing showing one embodiment of the present invention. Applicant: Mitsui Petrochemical Industries, Ltd. Agent Kazu Yamaguchi

Claims (1)

[Claims] (1) In a method for gas phase polymerization of olefin using a fluidized bed, the fine powder polymer-containing gas discharged from the upper part of the fluidized bed is guided to a cyclone, and the collected fine powder polymer is circulated to the fluidized bed polymerization vessel. At the same time, the circulation is at least 10mm from the wall of the polymerization vessel and 50mm from the bottom of the fluidized bed.
A method for vapor phase polymerization of olefins, characterized in that the process is carried out at a position inside a fluidized bed at a height of 415 m or more and a height of 415 m or less.