JPS6243442B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas phase polymerization method for olefins,
Continuous gas phase polymerization of olefins by overcoming problems of adhesion and clogging caused by fine powder polymers contained in the unreacted gas stream discharged from the gas phase polymerization zone of olefins with easy operations and means. This invention relates to an improvement method that can be carried out stably and smoothly over a long period of time.

More specifically, the present invention involves guiding an unreacted gas stream containing a finely divided polymer discharged from a gas phase polymerization zone of olefins to a cyclone to collect the finely divided polymer, and applying a suction force from the lower part of the cyclone. The present invention relates to a gas phase polymerization method for olefins, characterized in that the collected fine powder polymer is removed by suction from a cyclone, and the removed fine powder polymer is circulated to the gas phase polymerization zone. .

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, a method is adopted in which the unreacted gas flow is previously introduced into a cyclone to remove the finely divided polymer. At this time, the bottom of the cyclone is connected to the polymerization vessel, and the collected fine powder polymer is returned to the polymerization vessel by gravity due to its own weight.

However, in such conventional methods, the actual residence time of the fine powder polymer in the cyclone is not so short that it can be ignored, so it is difficult to avoid undesirable polymerization progressing in the cyclone, and the wall surface It was found that troubles such as adhesion and piping clogging are likely to occur, and this tendency is particularly remarkable when a highly active catalyst is used.

The present inventors conducted research in order to solve new technical problems that arise during cyclone treatment of such a flow of unreacted gas containing a finely divided polymer.

As a result, the above-mentioned troubles can be advantageously overcome by the extremely simple means of applying suction force from the lower part of the cyclone. By utilizing the ejector action of a high-speed gas flow that also serves as a gas flow to generate the above-mentioned suction force, which is extremely easy and simple in terms of operation and equipment, the above-mentioned new technical problems can be solved all at once and industrially advantageous. It has been discovered that the gas phase polymerization of olefins can be carried out stably and smoothly continuously over a long period of time.

Therefore, an object of the present invention is to provide a method that suppresses or prevents the above-mentioned troubles and enables continuous and stable operation over a long period of time.

The above objects and many other objects and advantages of the present invention will become more apparent from the following description.

According to the method of the present invention, an unreacted gas flow containing a finely divided polymer discharged from a gas phase polymerization zone for olefins is guided to a cyclone to collect the finely divided polymer, and a suction force is applied from the lower part of the cyclone. Let me,
The collected fine powder polymer is removed by suction from the cyclone, and the removed fine powder polymer is circulated to the gas phase polymerization zone.

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) of about 4 to about 100, especially about 6 to about 80, electron donor/titanium (molar ratio) of 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 alkyllithium, aryl sodium, alkylmagnesium, arylmagnesium, alkylmagnesium halide, arylmagnesium halide, alkylmagnesium hydride, trialkylaluminium, alkylaluminum halide, alkylaluminum hydride, alkyl Examples include 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., and homopolymerization or copolymerization of these to the extent that gas phase polymerization is possible. It can be performed.

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 can be carried out using a mixed type polymerization vessel such as a fluidized bed polymerization vessel, a stirred fluidized bed polymerization vessel, or the like. The reaction 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, particularly about 40 to 110°C. The polymerization pressure is preferably in the range of, for example, atmospheric pressure to about 150 kg/cm ² , particularly about 2 to about 70 kg/cm ² . 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. The 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 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, in order to prevent the fine powdery polymer collected by the cyclone from staying for a long time that may cause troubles such as adhesion to the vessel wall or clogging, suction force is applied from the lower part of the cyclone, and the fine powdery polymer is It is preferable to forcibly remove the coalescence and then quickly circulate the removed finely divided polymer to the gas phase polymerization zone.

Suitable means for accomplishing this include applying a high velocity gas flow across the lower part of the cyclone. Due to the ejector effect generated at this time, the fine powder polymer is suctioned away from the cyclone and is also sucked into the high-speed gas flow. Therefore, if this high-speed gas is directly supplied to the gas phase polymerization zone, the fine powder polymer can be circulated.

Suction with high-speed gas may be performed continuously, but in order to control the amount of unreacted gas leaking into the high-speed gas flow, a rotary valve, timer valve, etc. should be installed between the lower part of the cyclone and the high-speed gas flow pipe. A valve mechanism may be provided to perform the operation intermittently. In any case, forced suction removal makes it possible to shorten the residence time of the finely divided polymer in the cyclone, thereby making it possible to prevent problems such as wall adhesion and blockage. In addition, the fine powder polymer returned to the gas phase polymerization zone shows polymerization activity if it contains a catalyst, and not only contributes to improving the catalyst efficiency, but also grows into larger particles, so that the unreacted gas is recycled again. less likely to be accompanied by

The high-velocity gas used for the above-mentioned purpose, which serves both the suction action and accompanying gas action for the finely powdered polymer, may be any gas that does not adversely affect the polymerization. For example, olefins, diluents, hydrogen, or mixtures thereof used in polymerization can be used. The flow velocity of the high-speed gas only needs to show sufficient suction power at the communication part with the lower part of the cyclone, for example, 1
The speed may be approximately m/sec to 100 m/sec. If the pipe diameter of the communicating portion is appropriately reduced, there is no need to increase the amount of high-speed gas, so that the polymerization state will not be disturbed even if the gas is returned to the polymerization zone. As a method of returning the polymer to the polymerization zone, a method of directly supplying the polymer to the floating flow region, a method of spraying it into the region from above the region, etc. can be adopted.

On the other hand, the polymer extracted continuously or intermittently can be used as a product after appropriate post-treatment if necessary, or can be used in the next polymerization in the case of a multi-stage polymerization method.

An example of implementing the method of the present invention will be described below using the accompanying drawings.

Embodiment FIG. 1 is a drawing showing one embodiment of the present invention. In the fluidized bed polymerizer 3, 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 separate containers was passed through a tube 1 to a heater 2 to vaporize the liquid medium. After that, it is supplied to the polymerization vessel 3. The raw material olefin, hydrogen and diluent used as necessary are supplied to the polymerization vessel from the pipes 5 and 11 either freshly or by circulation, and the polymerization reaction is carried out while the fluidized bed 4 is fluidized. The unreacted gas that has passed through the fluidized bed is accompanied by a finely powdered polymer, so after being discharged from a pipe 7, it is led to a cyclone 8 to remove the powdery polymer. The unreacted gas from which the fine powder polymer has been removed is circulated from the pipe 11 through the cooler 13 and circulation blower 16 to the polymerization vessel. The lower part of the cyclone 8 is connected to a ventilator section 10 via a timer valve 9. There is a tube 1 in the ventilate part.
A high-speed gas is flowing through 2, and when the timer valve 9 opens, the fine powder polymer collected by the cyclone is sucked into the high-speed gas, and is entrained in the high-speed gas and circulated to the polymerization vessel 3. Ru. 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, the gas phase polymerization of olefins could be carried out continuously and smoothly over a long period of time.

[Brief explanation of the drawing]

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

Claims (1)

[Claims] 1. A flow of unreacted gas containing a finely divided polymer discharged from the gas phase polymerization zone of olefins is guided to a cyclone to collect the finely divided polymer, and a suction force is applied from the lower part of the cyclone. A method for gas phase polymerization of olefins, characterized in that the collected fine powder polymer is removed by suction from a cyclone, and the removed fine powder polymer is circulated to the gas phase polymerization zone. 2. Claim 1, wherein the suction force is provided by an ejector action by an accompanying gas that circulates the removed fine powder polymer into the gas phase polymerization zone.
Gas phase polymerization method described in section.