JP3216927B2 - Operating method of olefin polymerization reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a reactor for producing a polyolefin by a gas phase polymerization method. More specifically, the present invention relates to a method for restarting the operation of a polymerization reactor when producing a polyolefin by a gas phase polymerization method.

[0002]

2. Description of the Related Art In recent years, a method for producing a polyolefin by polymerizing an olefin in a gaseous state has been widely used because of its low cost. As a type of a reactor used for the gas phase polymerization of olefin, a fluidized bed type or a stirred bed type is mainly used (for example, JP-B-47-13962, JP-A-51-86584, etc.). When producing a polyolefin by a gas phase polymerization method, the operation of the polymerization reactor must be stopped urgently due to various troubles. For example, trouble occurred in the subsequent steps of the polymerization reaction (pelletization step, blending step, etc.), and the intermediate storage tank for polymer particles was full and there was no room, or a failure occurred in the circulating gas blower of the reaction system. For example. An emergency stop and reaction restart method usually performed in such a case is as follows. That is, a reaction terminating agent such as carbon monoxide gas or carbon dioxide gas is supplied into the reactor to stop the polymerization reaction (for example, JP-A-60-72904), and then the gas in the reaction system is purged with nitrogen. Purge. Thereafter, the polyolefin particles remaining in the reactor are drawn out of the reactor. Then, to restart the operation, new polyolefin particles are first introduced into the reactor, the system is purged with nitrogen, and then the procedure for starting up the reaction is repeated.

Here, first, a reaction stopping mechanism using a reaction terminator is considered. First, a reaction occurs between the reaction terminator and a catalyst or a cocatalyst, and as a result, the catalyst loses its function and the reaction stops. Will be. The reaction between the reaction terminator and the catalyst or cocatalyst has been analyzed for some time, but the effect of the reaction product on the polymerization reaction has not been sufficiently clarified. There is a similar concern when a reaction terminator remains in the system. Therefore, the reaction is stopped by the reaction terminator as described above,
When resuming after that, substantially all of the polyolefin particles remaining in the system as well as the gas in the system are exhausted out of the system, and then, after the polyolefin particles are newly charged into the system, the gas and catalyst are supplied. Then, the conventional method is to restart the operation. That is, although the operation is restarted, a method that is almost the same as the case of starting the operation completely new has been adopted.

[0004] Further, in the operation of a gas-phase polymerization reactor for polyolefin, it is described in detail in a previous patent publication that there are many troubles due to the formation of a sheet-like polymer at the beginning of the operation (for example, Japanese Patent Publication No. Sho 63). −500176
JP-A-1-230607, JP-A-2-14560
No. 8 and JP-A-2-135205). Accordingly, many troubles due to the formation of the sheet-like polymer were observed in the early stage of the restart of the operation.

[0005]

As described above, when the reactor is restarted after the polymerization reaction of the polyolefin is immediately stopped by supplying a reaction terminator, the conventional method is as follows. There were serious disadvantages. (1) In the early stage of the operation of the polyolefin reactor, a sheet-like polymer is likely to be generated, and when this occurs, the pipes and valves are closed, and the operation must be stopped. (2) At the start of operation, a method is usually adopted in which the supply amount of catalyst is gradually increased to gradually increase the production rate of polyolefin. Therefore, transient non-steady state continues, resulting in non-standard products during this period. (3) When discharging the polyolefin particles in the reactor out of the system or introducing new polyolefin particles, it is necessary to open the reactor to the atmosphere, and impurities such as moisture and oxygen are likely to be mixed. Therefore, when restarting the operation, the polymerization reaction hardly occurred and it took a long time to reach a steady operation. This phenomenon is particularly remarkable when the reaction system is opened to the atmosphere for a long period of time. Therefore, there has been a strong demand for a simple operation restarting method when the operation of the polyolefin reactor is stopped by introducing a reaction terminator.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, after stopping the reaction by introducing a gaseous reaction terminating agent, the gaseous reaction terminating agent was removed. The present invention has been found that the operation of the reaction after the restart is facilitated by discharging the organic particles after the discharge without discharging the polymer particles to the outside of the reaction system and supplying the organoaluminum compound. Reached. That is, in the first aspect of the present invention, a catalyst comprising a solid catalyst component containing at least titanium and / or vanadium and magnesium and an organoaluminum compound is supplied to a reactor, and olefin is constantly polymerized or copolymerized in a gas phase. After the polymerization, the polymerization reaction is stopped by introducing a gaseous reaction terminator into the system, and then the operation of the reactor is restarted. (1) The gaseous reaction terminator is introduced into the reaction system. A step of stopping the reaction by introducing
(2) a step of discharging the introduced gaseous reaction terminating agent out of the system; and (3) a step of restarting the operation, in which a reaction is started by first introducing an organoaluminum compound into the system. An operation method for an olefin polymerization reactor characterized in that the entire operation from the reaction stop to the reaction restart is performed without substantially discharging the polymer particles existing in the reaction system to the outside of the system. is there. Further, the second aspect of the present invention is a method wherein the gaseous reaction terminator is any one of gaseous reaction terminators selected from oxygen, water vapor, carbon monoxide, carbon dioxide, alcohols and ketones. To provide.

Hereinafter, the present invention will be described in detail. The olefin used in the present invention usually has 2 to 8 carbon atoms,
Preferably 2 to 6 olefins, for example ethylene, propylene, butene-1, pentene-1, hexene-1,
Α-olefins such as 4-methylpentene-1. Using these, homopolymerization or copolymerization at an appropriate ratio can be carried out. Examples of the copolymerization include copolymerization of ethylene such as ethylene / propylene, ethylene / butene-1, ethylene / hexene-1, and ethylene / 4-methylpentene-1 with an α-olefin having 3 to 12 carbon atoms, Copolymerization with butene-1, and copolymerization of ethylene with two or more other α-olefins, and the like. Further, for the purpose of modifying polyolefin, copolymerization using a diene is also possible. Examples of the diene used for this include butadiene, 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene and the like. The supply of the olefin to the reaction system can preferably be provided with a suitable inert carrier gas, for example nitrogen.

As the catalyst used for the polymerization of the olefin, a catalyst comprising at least a solid catalyst component containing titanium and / or vanadium and magnesium and an organoaluminum compound is used. Examples of the solid catalyst component containing at least titanium and / or vanadium and magnesium include a solid catalyst component containing titanium and magnesium and a solid catalyst component containing vanadium and magnesium used in a conventionally known Ziegler-based catalyst as an olefin polymerization catalyst. Alternatively, a solid catalyst component containing titanium, vanadium and magnesium can be used.

The solid catalyst component includes, for example, metallic magnesium, magnesium hydroxide, magnesium carbonate,
Magnesium oxide, magnesium chloride, etc., silicon,
Double salts, double oxides, carbonates, chlorides or hydroxides containing an element selected from aluminum and calcium and a magnesium atom, and furthermore, these inorganic solid compounds include oxygen-containing compounds, sulfur-containing compounds and aromatic carbonized compounds. Examples thereof include those in which a titanium compound and / or a vanadium compound are supported by a known method on a magnesium-containing inorganic solid compound such as a compound treated or reacted with hydrogen or a halogen-containing substance.

Examples of the oxygen-containing compound include water; polysiloxane; organic oxygen-containing compounds such as alcohols, phenols, ketones, aldehydes, carboxylic acids, esters, and acid amides; metal alkoxides; and inorganic compounds such as metal oxychlorides. Oxygen compounds can be exemplified. Examples of the sulfur-containing compound include organic sulfur compounds such as thiol and thioether, and inorganic sulfur compounds such as sulfur dioxide, sulfur trioxide, and sulfuric acid. Examples of the aromatic hydrocarbon include various monocyclic or polycyclic aromatic hydrocarbons such as benzene, toluene, xylene, anthracene, and phenanthrene. Examples of the halogen-containing substance include chlorine, hydrogen chloride, metal chloride, and organic halide.

The titanium compounds include titanium halides, alkoxy halides, alkoxides,
Halogenated oxides and the like can be mentioned. Of these, a tetravalent titanium compound and a trivalent titanium compound are preferable, and specific examples of the tetravalent titanium compound include a compound represented by the general formula Ti (OR) _n X _4-n (where R is carbon A hydrocarbon group such as an alkyl group, an aryl group, or an aralkyl group represented by the formulas 1 to 20, X represents a halogen atom, and n is a number in the range of 0 ≦ n ≦ 4). Specifically, titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, monomethoxytrichlorotitanium, dimethoxydichlorotitanium, trimethoxymonochlorotitanium, tetramethoxytitanium, monoethoxytrichlorotitanium, diethoxydichlorotitanium, triethoxymonochlorotitanium , Tetraethoxytitanium, monoisopropoxytrichlorotitanium, diisopropoxydichlorotitanium, triisopropoxymonoc Titanium, tetraisopropoxytitanium, monobutoxytrichlorotitanium, dibutoxydichlorotitanium, tributoxymonochlorotitanium, tetrabutoxytitanium, monopentoxytrichlorotitanium, monophenoxytrichlorotitanium, diphenoxydichlorotitanium, triphenoxymonochlorotitanium, tetraphenoxytitanium And the like. Examples of the trivalent titanium compound include a compound represented by the general formula Ti (OR) _m X _4-m (where R represents a hydrocarbon group such as an alkyl group, an aryl group, or an aralkyl group having 1 to 20 carbon atoms, and X represents a halogen atom). Represents an atom, and m is a number in the range of 0 <m <4.)
And trivalent titanium compounds obtained by reducing a monovalent alkoxyhalogenated titanium with hydrogen, aluminum, titanium or an organometallic compound of a metal from Groups I to III of the periodic table.

Of the above titanium compounds, tetravalent titanium compounds are particularly preferred. Specific ones of these catalysts, for example, MgO-RX-TiCl ₄ type (JP-B 51-
3514 _{JP), Mg-SiCl 4 -ROH-} TiCl 4 type (JP-B 50-23864 discloses), MgCl ₂ -Al (O
R) ₃ -TiCl ₄ system (JP-B-51-152, JP-B-52-15111), MgCl ₂ -SiCl ₄ -RO
H-TiCl ₄ system (JP-A-49-106581), M
g (OOCR) ₂ -Al (OR) ₃ -TiCl ₄ system
11710 JP), Mg-POCl ₃ -TiCl ₄ system (JP-B 51-153 discloses), MgCl ₂ -AlOCl-TiCl ₄
System (Japanese Patent Publication No. 54-15316), MgCl ₂ -Al
_{(OR) n -X 3-n} -Si (OR ') m -TiCl 4 system (JP 56
Preferred examples include a combination of a solid catalyst component (in the above formula, R and R 'represent an organic residue, and X represents a halogen atom) such as an organic aluminum compound.

Examples of the vanadium compound include tetravalent vanadium compounds such as vanadium tetrachloride, vanadium tetrabromide, and vanadium tetraiodide; pentavalent vanadium compounds such as vanadium oxytrichloride and orthoalkyl vanadate;
Examples include trivalent vanadium compounds such as vanadium trichloride and vanadium triethoxide. The vanadium compound is used alone or in combination with a titanium compound.

As another example of the catalyst system, a catalyst product obtained by using a reaction product of an organic magnesium compound such as a so-called Grignard compound and a titanium compound and / or a vanadium compound as a solid catalyst component, and combining the product with an organic aluminum compound is used. Can be exemplified. As the organomagnesium compound, for example, the general formula RMgX,
R ₂ Mg, magnesium compound represented by RMg (OR), etc. (wherein, R represents an organic residue having 1 to 20 carbon atoms, X is a halogen atom.) And their ether complexes or their organic magnesium compound, Further, a compound modified by adding another organic metal compound, for example, organic sodium, organic lithium, organic potassium, organic boron, organic calcium, organic zinc or the like can be used. Specific examples of the catalyst systems, for example, RMgX-TiCl ₄ type (JP-B 50-39470 discloses), RMgX- phenol -TiCl ₄ system (JP-B 54-12953 discloses), RMg
X-halogenated phenol-TiCl ₄ system (Japanese Patent Publication No. 54-
No. 12954) and RMgX-CO ₂ -TiCl ₄ (Japanese Patent Application Laid-Open No. 57-73009), in which an organic aluminum compound is combined with a solid catalyst component.

As another example of the catalyst system, an inorganic oxide such as SiO ₂ , Al ₂ O ₃ and SiO ₂ .Al ₂ O ₃ and the above-mentioned titanium and / or vanadium and magnesium are contained as solid catalyst components. An example is a solid substance obtained by contacting a solid catalyst component with an organic aluminum compound. The inorganic oxides include SiO ₂ , Al ₂ O ₃ and SiO ₂ .Al
_In addition to ₂ O _{3 and the} like, CaO, B ₂ O ₃ , SnO _{2 and the} like can be mentioned, and a double oxide of these oxides can also be used. A known method can be employed as a method for bringing the various inorganic oxides into contact with a solid catalyst component containing titanium, vanadium, and magnesium. That is, at a temperature of 20 to 400 in the presence or absence of an organic solvent such as an inert hydrocarbon, alcohols, phenols, ethers, ketones, esters, amines, nitriles or a mixture thereof.
° C, preferably 50 to 300 ° C, usually for 5 minutes to 20 ° C.
Although a method of reacting for a time is used, the reaction may be performed by a method of co-milling treatment or a method of appropriately combining them. Specific examples of the catalyst system include:
For example, SiO ₂ -ROH-MgCl ₂ -TiCl ₄ (JP-A-56
-47407), SiO ₂ -ROR'-MgO-AlC
l ₃ -TiCl ₄ (JP-A-57-187305), Si
O ₂ -MgCl ₂ -Al (OR) ₃ -TiCl ₄ -Si (OR ') ₄
(JP-A-58-21405), SiO ₂ —TiCl _{4
-R n AlCl 3-n -MgCl 2} -Al (OR ') n Cl 3-n ( _{JP-A-3-35004), SiO 2 -TiCl 4 -R} n AlX
_{3-n -MgCl 2 -Al (OR} ') n Cl 3-n -Si (OR'') m Cl
_4-m (JP-A-3-64306), SiO ₂ -MgCl
₂ -Al (OR ') _n Cl _3-n -Ti (OR'') ₄ -R _n AlCl
_3-n (JP-A-3-153707), SiO ₂ -MgC
l ₂ -Al (OR ') _n Cl _3-n -Ti (OR'') _n Cl _4-n -R _n Al
Cl _3-n (JP-A-3-185004), SiO ₂ -Ti
_{Cl 4 -R n AlCl 3-n} -MgCl 2 -Al (OR ') n Cl 3-n -
R ″ _m Si (OR ′ ″) _n X _{4- (m + n)} (Japanese Patent Application No. 2-41526 ₎
5 JP), SiO ₂ -R _n MgX _{2 over n -Al (OR ') n Cl} 3-n
-Ti (OR ") _n Cl _4-n -R"'OH-R _n AlX _3-n (Japanese Patent Application No. 3-94983), SiO ₂ -MgCl ₂ -Al (O
R ') _n Cl _3-n -Ti (OR ") _n Cl _4-n -R"' OH-R _n Al
Cl _3-n -Al (OR ') _n Cl _3-n (Japanese Patent Application No. 3-48643) (wherein R, R', R "and R"'represent a hydrocarbon residue) ) And the like in combination with an organoaluminum compound.

In these catalyst systems, a titanium compound and / or a vanadium compound can be used as an adduct with an organic carboxylic acid ester, and the above-mentioned inorganic solid compound containing magnesium is contact-treated with an organic carboxylic acid ester. It can be used later. Further, an organic aluminum compound can be used as an adduct with an organic carboxylic acid ester. Also, in all cases, a catalyst system prepared in the presence of an organic carboxylic acid ester can be used. Examples of the organic carboxylic acid ester used herein include various esters of aliphatic, alicyclic, and aromatic carboxylic acids, and an aromatic carboxylic acid ester having 7 to 12 carbon atoms is preferably used.
Specific examples include alkyl esters of benzoic acid, anisic acid, and toluic acid such as methyl and ethyl.

In the present invention, the organoaluminum compound used together with the above-mentioned solid catalyst component refers to an organoaluminum compound having at least one aluminum-carbon atom bond in a molecule. For example, (i) the general formula R _m Al (O
_{R ') n H p X q} ( wherein, R and R' are typically 1 carbon atom
A hydrocarbon group containing from 1 to 15, preferably 1 to 4, such as an alkyl group, an aryl group, an alkenyl group, a cycloalkyl group and the like, and in the case of an alkyl group, methyl, ethyl, propyl, isopropyl, isobutyl, sec. -Butyl, tert-butyl, hexyl, octyl and the like. R and R 'may be the same or different. X
Represents a halogen atom, and m, n, p and q are respectively 0 <m ≦ 3, 0 ≦ n <3, 0 ≦ p <3 and 0 ≦ q <3.
And satisfies m + n + p + q = 3. An organoaluminum compound represented by), represented by (ii) the general formula MALR ₄ (where, M is a metal selected from lithium, sodium or potassium, R is the same hydrocarbon group as above.) And complex alkylated products of Group I metals and aluminum in the periodic table.

Examples of the organoaluminum compound belonging to the above (i) include, for example, a general formula R _m Al (OR ') _{3 -m} (where R and R' are the same hydrocarbon groups as described above. M is preferably A number in the range of 1.5 ≦ m ≦ 3), a general formula R _m AlX _3−m (where R is the same hydrocarbon group as described above. X represents a halogen atom, and m is preferably m 0 <m <3), a general formula R _m AlH _{3 -m} (where R is the same hydrocarbon group as described above. M is preferably a number in the range of 2 ≦ m <3) And R _m Al (OR ′) _n X _q (where R and R ′ are the same hydrocarbon groups as above. X represents a halogen atom, and m, n and q are preferably M0 <m ≦ 3, 0 ≦ n <3, 0 ≦ q <3, respectively
And the number satisfies m + n + q = 3. ) Can be exemplified.
Specific examples of the organoaluminum compound belonging to (i) include trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, tri-sec-butylaluminum, and tri-aluminum.
trialkylaluminums such as tert-butylaluminum, trihexylaluminum and trioctylaluminum; trialkenylaluminum; dialkylaluminum alkoxides such as diethylaluminum ethoxide and dibutylaluminum butoxide; alkylaluminums such as ethylaluminum sesquiethoxide and butylaluminum sesquibutoxide In addition to sesquialkoxides, partially alkoxylated alkylaluminums having an average composition represented by R _2.5 Al (OR) _0.5 ; dialkylaluminum halides such as diethylaluminum chloride, dibutylaluminum chloride, diethylaluminum bromide; ethyl Aluminum sesquichloride, butyl aluminum sesquichloride, ethyl aluminum sesquichloride Partially aluminum halides such as alkylaluminum sesquihalides such as bromide; dialkylaluminum hydrides such as diethylaluminum hydride and dibutylaluminum hydride and alkylaluminum dihydrides such as ethylaluminum dihydride and propylaluminum dihydride; Examples thereof include partially hydrogenated alkylaluminums; partially alkoxylated and halogenated alkylaluminums such as ethylaluminum ethoxycyclolide, butylaluminum butoxycyclolide, and ethylaluminum ethoxybromide. The organoaluminum compounds belonging to the above (ii) include LiAl (C ₂ H ₅ ) ₄ and LiAl (C ₇ H ₁₅ )
_{4 and the} like. Further, as the organoaluminum compound similar to (i), an organoaluminum compound in which two or more aluminum atoms are bonded via an oxygen atom or a nitrogen atom can also be used. These compounds include, for example, (C ₂ H ₅ ) ₂ AlOAl (C ₂ H ₅ ) ₂ , (C ₄ H ₉ ) ₂ AlOAl
(C ₄ H ₉ ) ₂ and (C ₂ H ₅ ) ₂ AlN (C ₂ H ₅ ) Al (C ₂ H ₅ ) ₂ . Among these, trialkylaluminum is preferred.

The amount of the organoaluminum compound used during the steady operation is not particularly limited, but usually 0.05 to 1000 mol can be used per 1 mol of the titanium compound.

The polymerization reaction is carried out in the same manner as in the usual olefin polymerization reaction using a Ziegler type catalyst. That is, the reaction is performed substantially in the gas phase. As the olefin polymerization conditions, the temperature is 20 to 300 ° C, preferably 40 to 300 ° C.
The temperature is 200 ° C., and the pressure is normal pressure to 70 kgf / cm ² · G, preferably ^{2 to} 60 kgf / cm ² · G. The molecular weight can be adjusted to some extent by changing the polymerization conditions such as the polymerization temperature and the molar ratio of the catalyst. However, it can be effectively adjusted by adding hydrogen to the polymerization system. In the present invention, the reactor used for polymerizing or copolymerizing an olefin in a gaseous phase includes substantially all fluidized-bed systems operated in a gas-solid system, and has a stirrer or Any of those that do not have may be used. During the steady operation, the olefin, the solid catalyst component, and the organoaluminum compound are constantly introduced into the reaction system, while the produced polymer particles are extracted.

In stopping the reaction, the supply of the olefin, the solid catalyst component, and the organoaluminum compound is stopped,
The pressure and temperature in the system are appropriately lowered, and a gaseous reaction terminator is introduced into the system. As the gaseous reaction terminator of the present invention,
Oxygen, water vapor, carbon monoxide, carbon dioxide, alcohols such as methanol and ethanol, ketones such as acetone, and the like can be used. These can be appropriately mixed. The gaseous reaction terminator can be introduced into the system together with a suitable carrier gas, for example, a reactive gas such as olefin, or preferably a non-reactive carrier gas such as argon, helium, and particularly preferably nitrogen. It is difficult to precisely control the supply amount of the terminator to be introduced. In order to completely deactivate the catalyst, a large excess is usually introduced into the system. After confirming that the reaction has stopped, excess carbon dioxide gas is discharged out of the system. If necessary, the inside of the system is replaced with an inert gas such as nitrogen gas. In the present invention, the polymer produced by the polymerization and remaining in the reactor is kept in the system until the operation is resumed without being taken out of the system. The retention period is
There is no particular limitation as long as the airtightness of the reactor is maintained, and the reaction may be continued for several weeks or longer. That is, the polymer is placed in the reactor during the subsequent process of the polymerization reaction (for example, a powdering process, a pelletizing process, etc.) or a repair of a circulating gas blower of the reaction system which has caused the failure and stopped the reaction. Keep it.

Usually, before restarting the operation, it is preferable to discharge as much of the gaseous reaction terminator that has been supplied in advance for stopping the polymerization reaction to the outside of the system as much as possible. For this reason, the reaction system is purged with an inert gas to replace the gaseous reaction terminator. Nitrogen is preferred as the inert gas. The above gas replacement can also be performed at a stage after the reaction is stopped. In the replacement method, nitrogen may be continuously flowed in the system, or may be pressurized with nitrogen and then discharged to a vent. The concentration of the gaseous reaction terminator remaining in the system is 10 ppm or less, preferably 1 ppm or less under normal pressure after being discharged to the vent.
More preferably, the content is set to 0.1 ppm or less.

In the present invention, the polymer particles are kept in the system until the operation is restarted, and the organic aluminum compound is first supplied when the operation is restarted. A method of simultaneously supplying only the solid catalyst component or the solid catalyst component and the organoaluminum compound at the same time is conceivable, but in the present invention, it is important to supply only the organoaluminum compound first. The supply of the organoaluminum compound before the restart of the operation is desirably performed when nitrogen is circulated in the reaction system in order to make the dispersion of the organoaluminum compound uniform. In addition, the circulation of nitrogen has a pressure of 0 to 10 kgf /
cm ² · G, preferably carried out in 3~6kgf / cm ² · G. The temperature is the polymerization temperature, and is usually 10 to 100 ° C, preferably 40 to 90 ° C.

The amount of the organoaluminum compound supplied at the beginning of the restart of the operation may be the supply ratio during the steady operation, but is preferably based on 1 mol of the aluminum of the organoaluminum compound remaining in the reaction system before the shutdown. At least 1 mol, more preferably at least 2 mol. Even if it is added in a remarkably excessive amount, the effect does not increase so much and is uneconomical. Here, the inside of the reaction system includes the inside of the polyolefin particles in the reactor, the inside of the circulating gas, and the walls of the reaction system. The supply speed at this time can be appropriately selected. The amount of the organoaluminum compound remaining in the reaction system before stopping can be determined as the product of the supply rate of the organoaluminum and the average residence time of the polymer particles in the reactor.

After supplying a predetermined amount of the organoaluminum compound, olefin gas and hydrogen as a molecular weight regulator are introduced while circulating nitrogen, and the pressure is gradually increased by these. It is desirable that the supply flow ratio of each olefin gas and hydrogen be the same as the final composition ratio of the reaction system. Next, the solid catalyst component is supplied into the reactor together with an inert gas such as nitrogen. The polymerization reaction starts with the supply of the solid catalyst component, the amount of polyolefin produced gradually increases, and reaches a state of steady operation. Thereafter, the polymerization reaction proceeds steadily by adjusting the supply amounts of the olefin, the solid catalyst component, the organoaluminum compound and the like to the respective predetermined supply amounts in the steady state.

[0026]

EXAMPLES The present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to these examples.

<Preparation Example of Solid Catalyst Component> In a 500 ml three-necked flask equipped with a stirrer and a reflux condenser, 600
50 g of SiO ₂ baked at 100 ° C, dehydrated hexane 1
60 ml and 2.2 ml of titanium tetrachloride were added, and reacted under reflux of hexane for 3 hours. After cooling, a solution of diethylaluminum chloride in hexane (1 mmol / cc) was added for 30 m.
After reacting again under reflux of hexane for 2 hours, the mixture was dried at 120 ° C. under reduced pressure to remove hexane. The obtained reaction product is designated as component (I). Separately, the diameter 1 /
A stainless steel pot having a capacity of 400 ml containing 25 2 inch stainless steel balls was charged with 10 g of commercially available anhydrous magnesium chloride and 4.2 g of aluminum triethoxide, and ball milled at room temperature under a nitrogen atmosphere for 16 hours. Was performed to obtain a reaction product. This is designated as component (II). 5.4 of the above component (II)
g was dissolved in 160 ml of dehydrated ethanol, and the total amount of the solution was added to a three-necked flask containing the component (I). The mixture was reacted under reflux of ethanol for 3 hours, and dried under reduced pressure at 150 ° C. for 6 hours. A catalyst component was obtained. The content of titanium in 1 g of the obtained solid catalyst component was 15 mg.

<Embodiment 1> The same as that shown in FIG.
A fluidized bed reactor 1 with a diameter of 25 cm was used. 12 kg of a linear low-density polyethylene having an average particle size of 780 μm, which had been dried in advance, was charged into a reactor as a seed polymer. Next, the pressure in the reaction system was increased to 5 kgf / cm 2 · G with nitrogen gas, and the gas in the system was flowed through a fluid bed reactor 1, a gas circulation pipe 12, a blower 13 and a cooler 14 using a blower 13. Circulation was performed at 88 m ³ / hr, and the temperature was maintained at 85 ° C. by adjusting the circulating gas temperature. Hydrogen / ethylene / butene-1 ratio (molar ratio, hereinafter the same) in gas phase = 0.1 /
The amount of each gas was adjusted so as to be 1 / 0.4 and the nitrogen concentration was 25 mol%, and the total pressure was maintained at 20 kgf / cm ² · G. As a cocatalyst, triethylaluminum 1.1 g /
The solid catalyst component containing Ti and Mg obtained in the preparation example of the solid catalyst component is supplied as a hexane solution at a rate of 0.8 g / hr at a rate of 0.8 g / hr.
And the polymerization reaction was started. After 15 hours, the reaction was in a steady state, after which the operation continued smoothly. The production rate of the ethylene / butene-1 copolymer discharged through the polymer particle discharge valves 15 and 16 was 4.0 kg / hr.
The properties are MFR 0.88 g / 10 min, density 0.9
208 g / cm ³ , white in appearance, average particle size 760 μm
m were clean particles. The amount of the polymer particles retained in the fluidized bed reactor was 12 kg estimated from the indication of a differential pressure gauge (not shown) above and below the fluidized bed, and the average residence time of the polymer particles was 3 hours. Was.

Next, in order to perform an emergency stop of the polymerization reaction, 3 g of carbon monoxide gas was supplied into the circulating gas through a gaseous reaction terminator supply pipe 9. Immediately thereafter, the temperature of the circulating gas used for cooling sharply increased, and the increase in the differential pressure of the fluidized bed was stopped, confirming that the polymerization reaction was stopped. The circulating gas is released from the vent pipe 11, and the pressure in the system is increased to 6 kgf in 20 minutes.
/ cm ² · G and at the same time the temperature was reduced to 50 ° C. Using the blower 13, the gas in the system is flowed at 16m ³ / hr
While nitrogen was introduced from the nitrogen supply pipe 10 while maintaining the pressure at 6 kgf / cm ² · G. After 5 hours, the blower 13 was stopped, and gas was discharged from the vent pipe 11 until the pressure in the system reached normal pressure. Subsequently, the operation of increasing the pressure of the system to 5 kgf / cm ² · G with nitrogen and then releasing the system to normal pressure was repeated three times to purge carbon monoxide gas. In the fluidized-bed reactor, the polymer particles were kept for 20 hours while leaving them.

After the pressure in the fluidized bed reactor was increased to 5 kgf / cm ² · G with nitrogen, the gas in the system was circulated using the blower 13 at a flow rate of 88 m ³ / hr, and the temperature was raised to 85 ° C. by adjusting the temperature. did. At this time, the concentration of carbon monoxide in the circulating gas was 0.1 p.
pm or less. Thereafter, triethylaluminum was supplied at a rate of 10 g / hr for 2 hours (total 20 g). Subsequently, the hydrogen / ethylene / butene-1 ratio in the gas phase = 0.1.
Each gas was supplied so as to be /1/0.4 and the nitrogen concentration was 25 mol%, and the total pressure was increased to 20 kgf / cm ² · G.
After the total pressure reaches 20 kgf / cm ² · G, supply of triethylaluminum is started at a rate of 1.1 g / hr and solid catalyst component is fed at a rate of 0.8 g / hr as in the first operation. did. After 12 hours, the reaction reached a steady state, the production rate of the polymer particles was 4.0 kg / hr as before, and the operation continued smoothly. The obtained ethylene / butene-1 copolymer had a MFR of 0.85 g / 10 min and a density of 0.9221 g / c.
m ³ , which was almost the same value as the polymer particles obtained in the first operation.

<Embodiment 2> Similar to that shown in FIG.
A fluidized bed reactor 1 with a diameter of 25 cm was used. 12 kg of a linear low-density polyethylene having an average particle diameter of 830 μm, which had been dried in advance, was charged into a reactor as a seed polymer. Next, the pressure in the reaction system was increased to 5 kgf / cm ² · G with nitrogen gas, and the gas in the system was passed through a fluidized bed reactor 1, a gas circulation pipe 12, a blower 13 and a cooler 14 using a blower 13. Circulation was performed at a flow rate of 88 m ³ / hr, and the temperature was maintained at 85 ° C. by adjusting the circulating gas temperature. The amount of each gas was adjusted so that the ratio of hydrogen / ethylene / butene-1 in the gas phase was 0.1 / 1 / 0.4 and the nitrogen concentration was 25 mol%, and the total pressure was 20 kgf / cm ² · G. Held. As a cocatalyst, triethylaluminum was supplied as a hexane solution at a rate of 0.5 g / hr from the cocatalyst supply pipe 5, and 0.8 g of the solid catalyst component containing Ti and Mg obtained in the preparation example of the solid catalyst component was obtained.
The polymerization reaction was started at a rate of / hr through the catalyst supply pipe 8. After 12 hours, the reaction was in a steady state, after which the operation continued smoothly. The production rate of the ethylene / butene-1 copolymer discharged through the polymer particle discharge valves 15 and 16 was 3.8 kg / hr, and the property was MFR
It was 1.0 g / 10 min, the density was 0.9185 g / cm ³ , the appearance was white, and the particles were clean with an average particle size of 810 μm. The amount of the polymer particles staying in the fluidized bed reactor was estimated from the indication of a differential pressure gauge (not shown) above and below the fluidized bed and was 1%.
2 kg, so the average residence time of the polymer particles was 3.2 hours.

Next, in order to perform an emergency stop of the polymerization reaction, 1 liter of dry air (8.3 mmO 2 as oxygen) at normal pressure and 20 ° C.
l) was pressurized with nitrogen and supplied into the circulating gas through a gaseous reaction terminator supply pipe 9. Immediately after that, the temperature of the circulating gas for cooling rapidly increased, and the increase in the differential pressure of the fluidized bed also stopped, confirming that the polymerization reaction was stopped. The circulating gas was released from the vent pipe 11, and the pressure in the system was lowered to 5 kgf / cm ² · G in 20 minutes, and at the same time, the temperature was lowered to 50 ° C. The gas in the system is supplied at a flow rate of 16 using the blower 13.
While discharging from the vent pipe at m ³ / hr, on the other hand, nitrogen was introduced through the nitrogen supply pipe 10 and the pressure was increased to 5 kgf / cm ² ·
G held. After 4 hours, the blower 13 was stopped, and gas was discharged from the vent pipe 11 until the pressure in the system reached normal pressure. Subsequently, the operation of increasing the pressure of the system to 5 kgf / cm ² · G with nitrogen and then releasing the system to normal pressure was repeated three times to purge oxygen. In the fluidized-bed reactor, the polymer particles were kept for 65 hours while leaving them.

After the pressure in the fluidized bed reactor was increased to 5 kgf / cm ² · G with nitrogen, the gas in the system was circulated at a flow rate of 88 m ³ / hr using a blower 13, and the temperature was raised to 85 ° C. by adjusting the temperature. did. At this time, the oxygen concentration in the circulating gas was 1 ppm. Thereafter, triethylaluminum was supplied at a rate of 5 g / hr for 2 hours (total 10 g). Subsequently, each gas was supplied so that the ratio of hydrogen / ethylene / butene-1 in the gas phase was 0.1 / 1 / 0.4 and the nitrogen concentration was 25 mol%, and the total pressure was 20 kgf / cm ² ··· Pressurized to G. Total pressure is 20kgf / cm ²・ G
, The supply of triethylaluminum was started at a rate of 0.5 g / hr and the solid catalyst component was fed at a rate of 0.8 g / hr, as in the first operation. After 16 hours, the reaction reached a steady state, the production rate of the polymer particles was 3.8 kg / hr as before, and the operation continued smoothly. The obtained ethylene / butene-1 copolymer has M
The FR was 0.95 g / 10 min and the density was 0.9190 g / cm ³ , which was a value almost consistent with the polymer particles obtained in the first operation.

<Comparative Example 1> All operations were performed in the same manner as in Example 1 except that the supply of triethylaluminum (10 g / hr × 2 hours, total 20 g) performed in Example 1 was not performed before restarting the operation. . That is, when restarting the operation after stopping the reaction by carbon monoxide, the operation was restarted by supplying the olefin, the solid catalyst component and the triethylaluminum to the reactor at the same supply ratio as in the steady state. As a result, the reaction did not occur easily, and the polymerization reaction started only after 14 hours. Further, after that, a sheet-like polymer was generated, and 18 hours after the start of the supply of the solid catalyst, the clogging occurred in the polymer discharge pipe from the fluidized-bed reactor, so that the operation was stopped.

<Comparative Example 2> In Example 1, after purging with carbon monoxide gas, triethyl aluminum was removed.
The operation was started at a rate of 10 g / hr for 2 hours (total 20 g), and then the operation was started. In this comparative example, the supply of the triethylaluminum was performed simultaneously with the supply of the solid catalyst component. Except for the above, the same operation was performed as in Example 1. That is, when restarting the operation, the olefin, the solid catalyst component and the triethylaluminum are supplied simultaneously, and the olefin and the solid catalyst component are supplied at the supply ratio and the supply rate in the steady state. The operation was performed at a speed of 10 g / hr in the same manner as when the operation was restarted. 1 from the start of supply of each reaction material
After 15 minutes, the polymerization reaction started, but a chip-shaped polymer was produced. Two hours later, the supply rate of triethylaluminum was changed from 10 g / hr to 1.1 g / hr, which is the steady state supply rate in Example 1, but the same two hours and 45 hours.
One minute later, the operation was stopped because the pipe for removing the polymer from the fluidized bed reactor was clogged.

<Comparative Example 3> The operation was started in the same manner as in Example 1, and after the operation was interrupted by supplying carbon monoxide gas, all the polymer particles in the fluidized bed reactor were discharged out of the system.
Thereafter, 12 kg of a seed polymer, which is a linear low-density polyethylene having an average particle diameter of 780 μm and dried in advance, is newly charged into the fluidized bed reactor, and the inside of the system is purged with nitrogen. And resumed in the same way. That is, the pressure in the reaction system is increased to 5 kgf / cm ² · G with nitrogen gas, and the gas in the system is passed through the fluidized bed reactor 1, gas circulation pipe 12, blower 13 and cooler 14 using the blower 13. At a flow rate of 88 m ³ / hr, and the temperature was kept at 85 ° C. by adjusting the circulating gas temperature. Hydrogen in gas phase /
The amount of each gas was adjusted so that the ethylene / butene-1 ratio was 0.1 / 1 / 0.4 and the nitrogen concentration was 25 mol%,
The total pressure was kept at 20 kgf / cm ² · G. As a cocatalyst, triethylaluminum was supplied as a hexane solution at a rate of 1.1 g / hr from the cocatalyst supply pipe 5, and 0.8 g of the solid catalyst component containing Ti and Mg obtained in the preparation example of the solid catalyst component was obtained. The polymerization reaction was started at a rate of / hr through the catalyst supply pipe 8. However, the polymerization reaction was not easily stabilized due to impurities present in the system, and the operation reached a steady state after 5 days.

[0037]

According to the present invention, in the operation of a polyolefin gas-phase polymerization reactor, after stopping the operation using a gaseous reaction terminator,
When restarting the operation without discharging the polymer particles in the reactor to the outside of the system, supply the organoaluminum compound first, and then supply the olefin gas and catalyst to start the reaction, so that the operation after the restart is quickly performed. A steady state can be reached, and steady operation without clogging of polymer particles can easily be continued.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a gas phase polymerization reaction device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fluidized bed reactor 2 upper space area 3 fluidized bed area 4 gas dispersion plate 5 promoter supply pipe 6 hydrogen supply pipe 7 olefin supply pipe 8 catalyst supply pipe 9 gaseous reaction stopper supply pipe 10 nitrogen supply pipe 11 vent pipe 12 Gas circulation pipe 13 Blower 14 Cooler 15, 16 Polymer particle discharge valve 17 Nitrogen supply pipe for charging catalyst

────────────────────────────────────────────────── (56) References US Patent 4,326,048 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 2/34 C08F 10/00-10/14 C08F 110 / 00-110/14 C08F 210/00-210/18

Claims (3)

(57) [Claims] 1. A catalyst comprising a solid catalyst component containing at least titanium and / or vanadium and magnesium and an organoaluminum compound is supplied to a reactor, and olefin is constantly polymerized or copolymerized in a gas phase. A method in which the polymerization reaction is stopped by introducing a gaseous reaction terminator into the system, and then the operation of the reactor is restarted. (1) By introducing the gaseous reaction terminator into the reaction system, Stopping the reaction, (2)
A step of discharging the introduced gaseous reaction terminating agent out of the system, and (3) a step of restarting the operation by first introducing an organoaluminum compound into the system to start the reaction, and in the reaction system when the reaction is stopped. An operation method for an olefin polymerization reactor, wherein the entire operation from the stop of the reaction to the restart of the reaction is performed without substantially discharging the polymer particles existing in the reaction system to the outside of the system. 2. The method for operating an olefin polymerization reactor according to claim 1, wherein the organoaluminum compound is an alkylaluminum. 3. The olefin polymerization reaction according to claim 1, wherein the gaseous reaction terminator is a substance selected from oxygen, steam, carbon monoxide, carbon dioxide, alcohols and ketones. Operation of the vessel.