JPH10195113A - Gas circulation apparatus for vapor-phase olefin polymerization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas circulation apparatus for vapor-phase olefin polymn. which dispenses with a large-scale separating or compressing apparatus, can inhibit the side reactions of an olefin, and hardly causes piping materials to brittle. SOLUTION: In a gas circulation apparatus 10 for vapor-phase olefin polymn. having a compressing apparatus 7 for compressing an unreacted gas discharged from a vapor-phase polymn. reactor 1 and a cooling apparatus 8 for cooling the gas compressed at the compressing apparatus, the surfaces of pipelines coming in contact with the circulated gas in the range of the compressing and cooling apparatuses are formed from a steel material (i) contg. up to 0.15wt.% C and 8-30wt.% Cr. The surfaces of pipelines coming in contact with the circulated gas in the range other than of the compressing and cooling apparatuses may be formed from stainless steel or carbon steel other than material (i). Pref., material (i) contains 3-40wt.% Ni.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas circulating apparatus for olefin gas phase polymerization, and more particularly, to an olefin hydrogenation reaction or an isomerization reaction in an unreacted gas circulation line which hardly occurs, and furthermore, embrittlement of piping material. The present invention relates to a gas circulation device for olefin gas phase polymerization in which the occurrence of gas is difficult.

[0002]

BACKGROUND OF THE INVENTION Conventionally, polyolefins such as homopolyethylene and linear low-density polyethylene (LLDPE) are generally prepared by solution polymerization, slurry polymerization using a catalyst such as a Ziegler type titanium catalyst or a metallocene catalyst. It is produced by a liquid phase polymerization method such as polymerization and is widely used for various uses such as a film forming material.

When such a polyolefin is produced by a gas phase polymerization method, the polyolefin is obtained in the form of particles after the polymerization, so that steps such as particle precipitation or particle separation from the polymerization solution are not required, and the production process can be simplified. In recent years, the production of polyolefins by the gas phase polymerization method has been actively studied since the production cost can be reduced.

In the gas phase polymerization of olefin, a fluidized gas containing olefin is usually compressed by a compression device such as a compressor or a blower and blown from a lower portion of the reactor to flow solid particles comprising a catalyst and a produced polyolefin. While the olefin is polymerized while forming a fluidized bed (bed), and the unreacted gas discharged from the upper part of the reactor is circulated to the reactor via the compression device. During this gas circulation, the unreacted gas is usually compressed and then heat of polymerization is removed by a heat exchanger to circulate the gas through the reactor.

[0005] The unreacted gas discharged from the reactor as described above contains, together with unreacted olefin, a catalyst component such as a transition metal compound, an organoaluminum compound, and hydrogen. Therefore, in a circulation device such as a gas circulation line pipe, a hydrogenation reaction of olefin (for example, hydrogenation of ethylene) or an isomerization reaction (for example,
Side reactions such as isomerization of 1-butene to 2-butene) occur.

[0006] Such side reactions are more likely to occur as the temperature rises. Specifically, when the circulating gas temperature rises to 80 ° C or higher, it occurs to a negligible extent, and becomes remarkable at 110 ° C or higher and becomes 135 ° C or higher. It progresses violently.

[0007] When such a side reaction occurs in the gas circulation line, not only the monomer or hydrogen as a raw material is lost, but also a step for separating and removing structural isomers (impurities) of olefins generated in the isomerization reaction is required. It is becoming. In particular, structural isomers with different double bond positions
Both the boiling point and the melting point are close to each other, and it is difficult to separate by a normal separation method such as distillation. If the separation is attempted, the distillation apparatus and energy cost become excessive.

The above-mentioned side reactions can be prevented by, for example, preventing the catalyst component from being mixed into the circulating gas system or deactivating the catalyst. However, these methods require a large-scale apparatus for separating the catalyst component. However, these methods are not advisable from the viewpoint of the productivity of polyolefin production as a whole, or require a deactivator removal treatment.

In the gas circulation line, the temperature of the gas containing the polymerization heat further rises due to the adiabatic compression during the gas compression, and the above-mentioned side reaction is apt to occur. It is also known that, under certain conditions, for example, the pressure in each stage is gradually increased and the temperature in each stage is increased while cooling in each stage to suppress the occurrence of the side reaction. The equipment becomes huge.

Under these circumstances, in the gas phase polymerization of olefins, large-scale separation equipment is not required, and the size of the compression equipment is not increased. There is a demand for a gas circulating apparatus that can suppress the reaction and reduce the loss of the reactant gas, thereby effectively circulating and recycling the gas.

The present inventor has conducted research on such a gas circulating apparatus. As a result, each part constituting the conventional gas circulating apparatus, particularly the pipes, is made of various steel materials selected from the viewpoints of workability, durability and cost. However, the gas contact surface of the piping of the circulation line at least in the section from the compression device to the cooling device of the gas circulation line is reduced to a C content of 0.15% by weight.
It is found that the above-mentioned problems can be solved by forming a steel material having a Cr content of 8 to 30% by weight and that the pipe material can be prevented from becoming brittle. Thus, the present invention has been completed.

[0012]

An object of the present invention is to provide a gas circulation system for olefin gas phase polymerization which can suppress olefin side reactions without requiring a large-scale separation facility or a compression facility, and can reduce the brittleness of piping materials. It is an object of the present invention to provide a gas circulation device for olefin gas-phase polymerization in which conversion is less likely to occur.

[0013]

SUMMARY OF THE INVENTION A gas circulation device for olefin gas phase polymerization according to the present invention comprises a compression device for compressing an unreacted gas discharged from a gas phase polymerization reactor, and a cooling device for cooling the gas compressed by the compression device. In the gas circulating device having the device, the contact surface of the pipe in the section between the compression device and the cooling device with the circulating gas has a C content of 0.15% by weight or less and a Cr content of 8 to 30% % Of steel (i).

According to the present invention, the contact surface of the piping other than the section from the compression device to the cooling device with the circulating gas is
(i) The stainless steel or carbon steel other than (i) may be used, and the contact surface between the gas exhaust port and the gas supply port of the reactor with the circulating gas may be formed of the steel (i). You may.

The steel (i) desirably contains Ni in an amount of 3 to 40% by weight. The temperature of the circulating gas flowing through the pipe from the compression device to the cooling device is usually 90 to 300 ° C.

In the present invention, the catalyst for gas-phase olefin gas phase polymerization may be, for example, a particulate carrier comprising an oxide of at least one element selected from Groups II, III and IV of the periodic table. Examples of the catalyst include a solid catalyst component on which a transition metal catalyst component of Table IVB is supported.

[0017]

DETAILED DESCRIPTION OF THE INVENTION The gas circulating apparatus for olefin gas phase polymerization according to the present invention will be specifically described below. In the present invention, the term "polymerization" may be used to mean not only homopolymerization but also copolymerization, and the term "polymer" includes not only homopolymers but also copolymers. Sometimes used in a meaning.

According to the present invention, there is provided a gas circulation device for olefin gas phase polymerization, comprising: a compression device for compressing an unreacted gas discharged from a gas phase polymerization reactor; and a cooling device for cooling the gas compressed by the compression device. In the above, the contact surface of the pipe in the section between the compression device and the cooling device with the circulating gas has a C content of 0.1.
It is formed of a steel material (i) having a content of 15% by weight or less and a Cr content of 8 to 30% by weight.

The gas-phase polymerization of olefins is preferably carried out continuously using a fluidized bed (bed) reactor. FIG. 1 schematically shows a gas phase polymerization process of olefin using a fluidized bed reactor.

In the gas phase polymerization of olefin, a fluidizing gas containing olefin is introduced into the polymerization reactor 1 from a gas supply port 2 through a gas dispersion plate 3 such as a perforated plate at the bottom of the polymerization reactor 1 by a compression device 7. The olefin is polymerized in the fluidized bed while continuously blowing to form a fluidized bed (reaction system) while keeping the solid particles containing the catalyst supplied from the supply port 4 in a fluidized state.

The types of the catalyst and the olefin supplied to the fluidized bed will be described in detail later, but the fluidizing gas is usually 0.4 to 1.5 m / sec, preferably 0.6 to 1.2 m / sec.
The gas is blown from the gas supply port 2 at a linear speed of about sec. The fluidizing gas may contain an inert gas such as nitrogen together with the olefin, or hydrogen as a molecular weight regulator.

[0022] In the fluidized bed, the polymerization conditions are the type and copolymerization ratio of olefin, etc. but fluidizing gas linear velocity, usually, the polymerization pressure is atmospheric pressure to 100 kg / cm ² preferably normal pressure to 50 kg / cm ² And a polymerization temperature of 50 to 1
The temperature is 20 ° C, preferably 60 to 100 ° C. The polymerization can be carried out in two or more stages under different reaction conditions.

The molecular weight of the polyolefin obtained can be adjusted by changing the polymerization conditions such as the polymerization temperature and by controlling the amount of hydrogen (molecular weight regulator) used.

The polyolefin particles generated in the fluidized bed are continuously or intermittently extracted from the polyolefin recovery port 5. On the other hand, the unreacted gas discharged from the gas outlet 6 in the upper part of the reactor 1 is circulated to the reactor 1 by the gas circulation device 10. The unreacted gas may contain hydrogen, an inert gas, and a catalyst component together with the unreacted olefin.

The gas circulating device 10 includes a compression device 7 for compressing unreacted gas discharged from the gas discharge port 6 of the reactor 1.
And a cooling device 8 for cooling the gas compressed by the compression device 7
And

The compression device 7 is specifically a blower, a compressor, or the like, and its structure is not particularly limited. For example, a reciprocating compressor that sucks and compresses gas by reciprocating a piston in a cylinder equipped with an intake valve and a discharge valve, or a high-speed rotation of an impeller, and the gas passing through the impeller is centrifuged. A pressurized centrifugal blower and the like can be mentioned. In such a compression device, the gas is usually adiabatically compressed to generate heat.

As the cooling device 8, a heat exchanger generally used for removing polymerization heat from unreacted gas can be used without particular limitation. The unreacted gas discharged from the gas discharge port 6 of the reactor 1 is circulated from the gas circulation line 9 to the gas supply port 2 via the compression device 7 and the cooling device 8 as described above.

The gas circulation line 9 includes a pipe 9a in a section from the gas outlet 6 of the reactor 1 to the inlet of the compressor 7, and a pipe 9b in a section from the outlet of the compressor 7 to the inlet of the cooling device 8. And a pipe 9c in a section from the outlet of the cooling device 8 to the gas supply port 2 of the reactor 1.

When the unreacted gas circulates through the gas circulation line 9 in the gas phase polymerization of olefin, the temperature of the circulating gas flowing through the pipe 9a is usually from 0 to 120.
° C and circulating gas (compressed gas) flowing through the pipe 9b
The temperature is usually 90 to 300 ° C, and the temperature of the circulating gas (compressed gas) flowing in the pipe 9c is usually 0 to 100 ° C.

In the present invention, the gas circulation device 10 may have two or more compression devices 7 and two or more cooling devices 8, respectively. Further, the compression device 7 may have a built-in cooling means, and a cooling device 8 may be further provided downstream of the gas outlet of the compression device 7.

As the compression device 7 having the cooling means 8a built therein, specifically, a cooling means (after cooler) 8a having a capacity capable of cooling a temperature rise during gas compression using water, air or the like as a cooling medium. And a compression device incorporating the same.

FIG. 2 shows such an aftercooler 8a.
1 shows an embodiment of a gas circulating device 10 having a compression device 7 and a cooling device 8 which incorporate therein. In FIG. 2, the unreacted gas discharged from the reactor 1 is guided to a compressor 7a via a circulation line (piping) 9a, compressed, and cooled by an aftercooler 8a via a piping 9b. When a condensed component is generated during this cooling, the compressed gas is once guided to the drain pot 7b through the normal pipe 9d to separate the condensed component. The gas phase is led from the drain pot 7b to the heat exchanger 8 via the pipe 9e. From the drain pot 7b, the gas phase is transferred to the compressor 7a through a line 9f.
Feedback. When the drain pot 7b is not required, the after-cooler 8
The compressed gas cooled in a is guided to the thermal cooler 8 via the line 9d.

In the present invention, among the pipes 9 constituting the above-mentioned circulation line, at least a pipe 9b in a section from the compressor 7 to the cooling device 8 (or from the gas outlet of the compressor 7a to the inlet of the aftercooler 8a). Is made of a steel material (stainless steel material) (i) having a C content of 0.15% by weight or less and a Cr content of 8 to 30% by weight.

The steel (i) preferably has a C content of 0.1% by weight or less and a Cr content of 10 to 20%.
%, Particularly preferably the C content is 0.05% by weight or less and the Cr content is 10 to 20% by weight.

The steel (i) preferably contains Ni, specifically 3 to 40% by weight, preferably 5 to 2% by weight.
It is desirable to contain it in an amount of 5% by weight, particularly preferably 8 to 20% by weight.

Examples of the steel material (i) having the above composition include stainless steel.
302 (AISI302), SUS303 (AISI303),
SUS304 (AISI304), SUS304L (AISI3
04L), SUS305 (AISI305), SUS309
S (AISI309S), SUS316 (AISI316), S
US316L (AISI316L), SUS317 (AISI3
17), SUS317L (AISI317L), SUS32
1 (AISI321) and SUS347 (AISI347). Among them, SUS304, SUS
316 is particularly preferred.

In the present invention, among the pipes constituting the circulation line 9, at least the gas contact surface of the pipe 9b may be formed of the steel material (i) as described above, and the pipes 9a and / or other than the pipe 9b may be used. The gas contact surface 9c may be formed of steel (i), or may be formed of a material other than steel (i), such as stainless steel or carbon steel other than steel (i).

In the gas circulation device 10 shown in FIG.
The materials of d, 9e and 9f may be the same as those of 9a and 9c. In the gas circulation device 10, when the calorific value during compression is small, the heat exchanger 8
(Or pipe 9b) to the inlet of (or aftercooler 8a)
However, when the compression ratio per compression unit is high and the amount of heat generated is large, it is desirable to use the pipe 9b up to the inside of the heat exchanger 8 (or aftercooler 8a).

In the present invention, the material of the outer peripheral portion of each pipe is not particularly limited, and may be formed of the same material as the gas contact surface, or the gas contact surface and the outer peripheral portion may be formed of different materials. Good.

According to the gas circulating apparatus according to the present invention as described above, in the gas circulating system during olefin gas phase polymerization,
It is difficult for side reactions such as hydrogenation reaction or isomerization reaction of olefins to occur, loss of unreacted gas is small, unreacted gas can be efficiently circulated, and embrittlement of gas circulation device is prevented. Can be.

Further, according to the present invention, a large-scale facility such as a catalyst component separating apparatus for suppressing a side reaction in a gas circulation system or a facility for separating impurities generated by a side reaction is not required, and equipment cost is not required. 9b, 9c, 9d, 9 other than the outer periphery of 9b, or 9b
When e and 9f are formed of an inexpensive material such as carbon steel, the cost of the circulation device can be further reduced.

In the gas-phase polymerization of olefin using the gas circulation device 10 having the above-described structure, the unreacted gas discharged from the reactor 1 is compressed, and the heat of polymerization of the gas is removed by the heat exchanger 8. Thereafter, the olefin is circulated to the reactor 1. At this time, the olefin supplied from the line 11 to the circulation line can be heated by utilizing the heat of polymerization.

In the present invention, specific examples of the olefin include ethylene, propylene, 1-butene, 1-pentene and 1-pentene.
Α-olefins having 2 to 18 carbon atoms such as hexene, 4-methyl-1-pentene, 1-octene and 1-decene;
Eighteen cycloolefins can be used. These may be homopolymerized or copolymerized.

If desired, other polymerizable monomers may be copolymerized with the olefin. For example, styrene, vinyl chloride, vinyl acetate, vinyl acrylate, methyl methacrylate, tetrafluoroethylene, vinyl ether, acrylonitrile, and other vinyl monomers may be used. Type monomers, conjugated dienes such as butadiene and isoprene, non-conjugated polyenes such as 1,4-hexadiene, dicyclopentadiene and 5-vinyl-2-norbornene, acetylenes such as acetylene and methylacetylene, and aldehydes such as formaldehyde Can also be copolymerized.

As the catalyst, a catalyst known as an olefin polymerization catalyst such as a metallocene catalyst, a Ziegler-type titanium catalyst and a Philippe-type chromium oxide catalyst can be used without any particular limitation.

Such an olefin polymerization catalyst is usually formed from a transition metal catalyst component, a cocatalyst component, and, if necessary, an electron donor. The transition metal catalyst component may be used in a solid state. desirable.

As the transition metal catalyst component, Periodic Table IV
A transition metal compound (A) selected from the group B is exemplified, and this transition metal compound is represented, for example, by the following formula (1). MLx (1) where M is Zr, Ti, Hf, V, Nb, Ta and C
a transition metal selected from r. L is a ligand coordinated to a transition metal, and is a hydrogen atom, a halogen atom, an oxygen atom,
An optionally substituted hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group, an aryloxy group, a trialkylsilyl group, an SO ₃ R group (where R represents a substituent such as halogen; A hydrocarbon group having 1 to 8 carbon atoms). x is the valence of the transition metal.

Examples of the halogen include fluorine, chlorine, bromine and iodine. Specific examples of the hydrocarbon group having 1 to 30 carbon atoms include a methyl group, an ethyl group, a propyl group,
Isopropyl group, alkyl group such as butyl group, cyclopentyl group, cycloalkyl group such as cyclohexyl group,
Examples include aryl groups such as a phenyl group, a tolyl group, and a cyclopentagenyl group, and aralkyl groups such as a benzyl group and a neophyl group.

A part of the cycloalkyl group, the aryl group and the aralkyl group may be substituted with a halogen atom, an alkyl group, a trialkylsilyl group or the like. When the hydrocarbon group is a cycloalkyl group, an aryl group, or an aralkyl group, and has a plurality of coordinates, ethylene,
It may be bonded via an alkylene group such as propylene, a substituted alkylene group such as an isopropylidene or diphenylmethylene group, a silylene group or a substituted silylene group such as a dimethylsilylene, diphenylsilylene, or methylphenylsilylene group.

Examples of the alkoxy group include a methoxy group, an ethoxy group and a butoxy group, and examples of the aryloxy group include a phenoxy group. Two or more transition metal compounds as described above may be used in combination.

When the solid catalyst component is formed from the transition metal catalyst component as described above, a fine particle carrier comprising an inorganic oxide of at least one element selected from Groups II, III and IV of the periodic table Is used.

Specific examples of such inorganic oxides include SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , B ₂ O ₃ ,
CaO, ZnO, BaO, etc. ThO _2, and mixtures thereof or mixtures containing these and other oxides, for example SiO ₂
-MgO, SiO ₂ -Al ₂ O ₃ , SiO ₂ -TiO ₂ , SiO ₂ -V ₂
O ₅ , SiO ₂ —Cr ₂ O ₃ , SiO ₂ —TiO ₂ —MgO or the like is used. Among them, those mainly containing one selected from SiO ₂ , Al ₂ O ₃ and MgO are preferred.

The fine particle carrier is preferably porous, has an average particle size of 1 to 300 μm, a specific surface area of usually 50 to 1000 m ² / g, and a pore volume of 0.3.
It is desirably about 2.5 cm ³ / g.

The solid transition metal catalyst component is obtained by, for example, contacting a magnesium compound, a titanium compound, an electron donor and the like, and is a solid titanium catalyst component containing magnesium, titanium, halogen and an electron donor. You may.

In preparing the solid titanium catalyst component,
Although each of the above compounds varies depending on the preparation method, for example, the electron donor is 0.01 per mole of the magnesium compound.
-5 mol, preferably 0.1-1 mol,
The titanium compound is used in an amount of 0.01 to 1000 mol, preferably 0.1 mol.
Desirably, it is used in an amount of 1 to 200 moles.

In such a solid titanium catalyst component, the halogen / titanium (atomic ratio) is about 2 to 200, preferably about 4 to 100, and the electron donor / titanium (molar ratio) is about 0.01. -100, preferably about 0.2-10, and magnesium / titanium (atomic ratio) is about 1-10.
It is desirably 0, preferably about 2 to 50.

The cocatalyst component is selected from (B) an organoaluminum compound, an organoaluminum halogen compound, an aluminum halide compound, an organic boron compound, an organic boronoxy compound, an organic boron halogen compound, a boron halide compound and an organic aluminumoxy compound. Compounds are used.

The compound group (B) is specifically represented by the following formula (2) except for the above-mentioned organic aluminum oxy compound. BRx (2) In the formula, B is an aluminum atom or a boron atom.

When the compound represented by the formula (2) is an organic aluminum compound or an organic boron compound, R is an alkyl group having 1 to 30 carbon atoms, and when the compound is an aluminum halogen compound or a boron halogen compound,
R is a halogen atom, and in the case of an organic aluminum halide or an organic boron halide, R is both an alkyl group having 1 to 30 carbon atoms and a halogen atom.

Examples of the halogen include fluorine, chlorine, bromine and iodine. Examples of the alkyl group having 1 to 30 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, and isobutyl. And the like.

The organoaluminum oxy compound is specifically represented by the following formula (3) or (4).

[0062]

Embedded image

In these formulas, R is a hydrocarbon group such as a methyl group, an ethyl group, a propyl group, a butyl group, etc.
Is an integer of 2 or more, preferably 5 to 40. The aluminoxane is an alkyloxyaluminum unit represented by the formula (OAl (R ¹ )) (R ¹ is the same group as R above)
And an alkyloxyaluminum unit represented by the formula (OAl (R ² )) (R ² is different from R ¹ and is the same group as R above)
And a mixed alkyloxyaluminum unit.

R in the alkyloxyaluminum unit may be a halogen or hydrogen alkoxy group, an aryloxy group, or a hydroxyl group if it is a part. Further, as the organic aluminum oxy compound, specifically,
And benzene-insoluble organoaluminum oxy compounds as exemplified in JP-B-78687.

These co-catalyst components (B) can be used in combination of two or more. It may be diluted with a hydrocarbon or a halogenated hydrocarbon before use. In the present invention, as a catalyst for olefin polymerization, an electron donor can be used as necessary together with the above-mentioned transition metal catalyst component and co-catalyst component. Examples of the electron donor include an ether compound, a carbonyl compound, and an alkoxy compound.

As the olefin polymerization catalyst as described above, specifically, a metallocene compound containing a metallocene compound (transition metal catalyst component), an organic aluminum oxy compound as a cocatalyst component and, if necessary, an organic aluminum compound is used. Catalysts may be mentioned. In this metallocene-type catalyst, it is desirable to use at least a transition metal catalyst component, preferably a transition metal catalyst component and a cocatalyst component, as a solid catalyst component supported on a particulate carrier.
In this case, the metallocene compound is used in an amount of usually 0.001 to 1.0 mmol, preferably 0.01 to 0.5 mmol, in terms of transition metal atom, per gram of the fine particle carrier, and the organic aluminum oxy compound. 1 g of this particulate carrier
0.1 to 100 mmol, preferably 0.5 to 2
It can be used in an amount of 0 mmol.

The olefin polymerization catalyst specifically includes a solid titanium catalyst comprising a solid titanium catalyst component and an organic aluminum compound.
As the organoaluminum compound, among the above cocatalyst components, trialkylaluminums such as trimethylaluminum, triethylaluminum, and triisobutylaluminum are preferably used.

In the present invention, the above-mentioned catalyst may be prepolymerized. The solid catalyst component or the prepolymerized catalyst component as described above is usually converted to a transition metal atom in the transition metal compound per 1 liter of polymerization volume, and is usually 0.000.
01-1.0 mmol / hr, preferably 0.0001-
Preferably, it is used in an amount of 0.1 mmol / hour.

[0069]

According to the gas circulating apparatus of the present invention, the olefin isomerization reaction or hydrogenation reaction in the gas circulating line in the gas phase polymerization is suppressed, and the reaction raw material gas is effectively prevented from being lost during circulation. Not only can it be reused, but also the step of removing impurities generated in the isomerization reaction or hydrogenation reaction can be eliminated.

Further, embrittlement of the gas circulating device, particularly the piping material, can be prevented.

[0071]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.
In the following examples, the hydrogenation rate or isomerization rate of olefin in a gas circulation line (pipe) during gas phase polymerization of olefin was simulated by using a test piece (pipe) of the following material. did.

[Test Piece] Sample-1: A 1.5-inch pipe of SUS304TPA (manufactured by Nippon Metal Industry Co., Ltd.) cut to a length of 10 mm. The composition is shown below. Sample-2: 1.5 inch pipe of STPG-38E (manufactured by Kawasaki Steel) cut to a length of 10 mm. The composition is shown below. Composition (% by weight) C Cr Ni Sample-1: SUS304TPA 0.05 18 8.2 Sample-2: STPG-38E 0.20 --- The method for preparing the prepolymerized catalyst (A) used below is Catalyst Preparation Example 1. It will be described later.

[0073]

[Example 1] [Ethylene hydrogenation reaction] A test piece of sample-1 was placed in a SUS316 21 autoclave (bottom part).
After sufficiently purging with nitrogen, the temperature was raised to 135 ° C., and the pressure was reduced to 0.3 KPa using a vacuum pump.

The pressure was returned to normal pressure with ethylene, and hydrogen was
After introducing up to Pa, 1 g of the prepolymerized catalyst (A) dispersed in 10 ml of decane was injected with ethylene. Ethylene was added so that the pressure of the autoclave became 1.9 MPa (gas composition at this time was 50 mol% for both hydrogen and ethylene).
After reacting at 135 ° C. for 3 hours, the gas composition was analyzed. As a result, the hydrogenation rate of ethylene to ethane was 7
Mole%.

[Isomerization reaction of 1-hexene] After the residual gas in the autoclave after the hydrogenation reaction was depressurized to normal pressure, 1 ml of 1-hexene was injected with ethylene, and ethylene was introduced to 0.5 MPa. After that, the mixture was reacted at 135 ° C. for 2 hours. After cooling to room temperature and depressurizing to normal pressure, the condensate in the autoclave was analyzed to measure the concentrations of hexane, 1-hexene, and 2-hexene, and the hydrogenation rate and isomerization rate of 1-hexene were determined. I asked.

As a result, the hydrogenation ratio of 1-hexene was 1 mol%, and the isomerization ratio was 2 mol%. Table 1 shows the results.

[0077]

Comparative Example 1 In the hydrogenation reaction of Example 1, the same reaction as in Example 1 was performed except that the test piece was changed to Sample-2. As a result, the hydrogenation ratio of ethylene was 30 mol%. The hydrogenation ratio of 1-hexene was 2 mol% and the isomerization ratio was 10 mol%.

[0078]

[Example 2] [Hydrogenation reaction of ethylene] The same reaction as in Example 1 was performed, except that triisobutylaluminum was used instead of the prepolymerization catalyst (A). As a result, the hydrogenation ratio of ethylene was 13 mol%.

[0079]

Comparative Example 2 [Ethylene hydrogenation reaction] The same reaction as in Example 2 was performed, except that the test piece was changed to Sample-2. As a result, the hydrogenation rate of ethylene was 40 mol%.

[0080]

Comparative Example 3 [Ethylene hydrogenation reaction] The same reaction as in Comparative example 2 was performed, except that the reaction temperature was changed to 110 ° C.
As a result, the hydrogenation ratio of ethylene was 24 mol%.

[0081]

Example 3 [Ethylene hydrogenation reaction] The same reaction as in Example 1 was performed, except that the hydrogen / ethylene ratio of the charged gas was changed to 10/90 (molar ratio). As a result, the hydrogenation ratio of ethylene was less than 1 mol%.

[0082]

Comparative Example 4 [Ethylene hydrogenation reaction] The same reaction as in Example 3 was performed, except that the test piece was changed to Sample-2. As a result, the hydrogenation rate of ethylene was 5 mol%.

[0083]

Example 4 [Ethylene hydrogenation reaction] The same reaction as in Example 1 was carried out except that the reaction temperature was changed to 80 ° C. As a result, the hydrogenation ratio of ethylene was less than 1%.

[0084]

Comparative Example 5 [Ethylene hydrogenation reaction] The same reaction as in Example 4 was performed, except that the test piece was changed to Sample-2. As a result, the hydrogenation rate of ethylene was 9 mol%.

[0085]

Example 5 [Hydrogenation reaction of propylene] The hydrogenation reaction of Example 2 was repeated except that triisobutylaluminum was changed to triethylaluminum, the reaction temperature was changed to 125 ° C., and the charged gas was changed to propylene. The same reaction as described above was performed. As a result, the hydrogenation rate of propylene to propane was 3
Mole%.

[0086]

Comparative Example 6 [Hydrogenation reaction of propylene] In the hydrogenation reaction of Example 5, the same reaction as in Example 5 was performed except that the test piece was changed to Sample-2. As a result, the hydrogenation ratio of propylene was 50 mol%.

[0087]

[Table 1]

[0088]

[Preparation Example 1 of Catalyst] [Preparation of Preliminary Polymerization Catalyst (A)] Preparation of Solid Catalyst Component (A)
6.9 g of silica dried for 0 hour and 100 ml of toluene
And then cooled to 0 ° C. Thereafter, 64 ml of a toluene solution of methylaluminoxane (Al; 0.83 mol / l) was added dropwise over 30 minutes. At this time, the temperature in the system was kept at 0 to 3 ° C. Subsequently, the reaction was carried out at 0 ° C. for 20 minutes, then, the temperature was raised to 95 ° C. over 1 hour, and the reaction was carried out at that temperature for 4 hours. Thereafter, the temperature was lowered to 60 ° C., and the supernatant was removed by a decantation method.

After the solid component thus obtained was washed twice with toluene, toluene was added thereto so that the total volume became 125 ml, and resuspended. 50 ml of this suspension was transferred to another glass flask, and a toluene solution of bis (1,3-n-butylmethylcyclopentadienyl) zirconium chloride (Zr; 23.8 mmol / l) 6 was added thereto. .
4 ml was added at room temperature (added so that the molar ratio of Al / Zr in the reaction system was 130), and the mixture was further reacted at 80 ° C. for 2 hours.

Thereafter, the supernatant was removed, and the residue was washed twice with hexane to obtain a solid catalyst component (A) containing 3.5 mg of Zr and 138 mg of Al per gram.

[0091] in hexane 130ml containing prepolymerized 7.7 mmol of triisobutylaluminum the solid catalyst component (A), obtained above solid catalyst component (A) 3.9 g and 1-hexene 0. 53 ml added, 3
Preliminary polymerization of ethylene was performed at 5 ° C. for 2 hours. The supernatant was removed, the residue was washed twice with hexane, the solid component was filtered off with a glass filter (G3), and then dried at room temperature with a vacuum pump for 2 hours to obtain a solid catalyst component ( A) A prepolymerized catalyst (A) containing 3.3 mg of Zr and 3 g of polymer per gram was obtained.

[Brief description of the drawings]

FIG. 1 schematically illustrates a gas phase polymerization process of an olefin.

FIG. 2 shows an embodiment of a gas circulation device for gas phase polymerization according to the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Ryoichi Yamamoto, 3 Chikusa Beach, Ichihara City, Chiba Prefecture Inside Mitsui Petrochemical Industry Co., Ltd. Chemical Industry Co., Ltd.

Claims (6)

[Claims] 1. A gas circulation apparatus for gas phase polymerization, comprising: a compression device for compressing unreacted gas discharged from a gas phase polymerization reactor; and a cooling device for cooling the gas compressed by the compression device. The contact surface of the piping between the device and the cooling device with the circulating gas should have a C content of 0.15% by weight or less and Cr
A gas circulation device for olefin gas phase polymerization, comprising a steel material (i) having a content of 8 to 30% by weight. 2. A contact surface of a pipe other than the section from the compression device to the cooling device with the circulating gas is formed of stainless steel or carbon steel other than the steel material (i). 2. The gas circulation device for olefin gas phase polymerization according to 1. 3. The steel material (i) has a contact surface with a circulating gas in all pipes from a gas discharge port to a gas supply port of the reactor.
The gas circulation device for olefin gas phase polymerization according to claim 1, wherein the gas circulation device is formed by the following. 4. The gas circulation apparatus for olefin vapor phase polymerization according to claim 1, wherein said steel material (i) contains Ni in an amount of 3 to 40% by weight. 5. The olefin gas phase according to claim 1, wherein the temperature of the circulating gas flowing through the pipe between the compression device and the cooling device is 90 to 300 ° C. Gas circulation device for polymerization. 6. The olefin gas phase polymerization catalyst according to claim 1, wherein
A catalyst comprising a solid catalyst component in which at least a transition metal catalyst component of Group IVB of the Periodic Table is supported on a fine-particle support made of an oxide of at least one element selected from Group II, Group III, and Group IV. The gas circulation device for olefin gas phase polymerization according to any one of claims 1 to 5, characterized in that: