JPS62156107A - Method and apparatus for minimizing formation of polymer aggregate or lump in polypropylene gaseous phase polymerization reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a process for the gas phase polymerization of monomers in a gas phase quench reaction vessel in which off-gas from the reactor is recycled. More specifically, the present invention provides a method for controlling the formation of polymer aggregates or lumps in a reactor used in polypropylene gas phase polymerization, on the one hand, at the location of catalyst injection into the reactor, and on the other hand, at the location of catalyst injection into the reactor. The present invention relates to a method and apparatus for minimizing catalyst yield and stereospecificity and polymer physical properties by controlling the injection location of cocatalysts and modifiers.

Description of the Prior Art Gas phase polymerization processes using gas phase quench reactors are described in U.S. 1 Ver. 3.957, incorporated herein by reference.
448; 3,965,083; 3,971,76
8; 4,101,289, which are incorporated herein by reference. These documents describe polymerization processes and apparatus in which JIJ polymers are formed from gaseous monomers in horizontal stirred bed reactors.

Typically, in the operation of such methods and apparatus, particles of polymer are formed around solid catalyst particles.

Horizontal reactors typically have hydrogen gas and −
There is recycled propylene gas introduced at the same time.

Liquid propylene is then injected into the reactor from the top of the reactor as a quenching liquid. Hydrogen is provided for molecular weight control.

A water wheel or other type of agitator inside the reactor stirs the reactor contents.

At the so-called upstream end of the reactor, a catalyst system consisting of a catalyst injected at a point into the top of the reactor, and cocatalysts and modifiers injected at a point adjacent to the injection point of the catalyst, are placed in the top of the reactor. injected inside.

Solid polypropylene powder is pumped out in the reactor and withdrawn downstream thereof.

It is desirable to deposit polymer particles as quickly as possible, and a number of different highly active catalyst systems have been developed for this purpose.

However, one of the problems encountered with such gas phase polymerization processes and apparatus using horizontal reactors with gas phase quenching is the formation of agglomerates within the powdered polymer product within the reactor.

Lumps in the product result in a product of non-uniform size, and clumps inside the reactor result in process interruptions requiring cleaning of the reactor before the process can continue. This is extremely costly and time consuming.

As will be described in greater detail below, the methods and apparatus of the present invention minimize the formation of polymer aggregates or lumps. This type of minimization of polymer aggregates or lumps involves introducing the catalyst into the reactor adjacent to the upstream end of the reactor and then introducing the cocatalyst and modifier into the reactor well downstream from the point of catalyst introduction. This resulted from the discovery that the formation of polymer aggregates is minimized, if not completely avoided, when introduced at a distance of approximately

Although it is not known with absolute certainty that separating the introduction of catalyst and cocatalyst and modifier can reduce the amount of catalyst and cocatalyst and modifier in the polymeric material and reactor with high concentrations of catalyst and modifier. Thorough mixing prior to interaction of polymeric material and catalyst facilitates slow activation of the catalyst and reduces, if not completely avoids, the formation of polymer agglomerates in the reactor. It is considered that

SUMMARY OF THE INVENTION According to the present invention, a quenched gas phase in a horizontal reaction vessel comprises contacting an olefin monomer or a mixture of olefin monomers with a polymerization catalyst system in the presence of hydrogen in a reactor to form a polymer product. An improved method for polymerizing olefin monomers is provided in which the titanium-containing catalyst component of the catalyst system is introduced into the top side of the reactor adjacent to the upstream end of the reactor, and the cocatalyst plus modifier of the catalyst system is The components are introduced into the top side of the reactor at a distance downstream of the point of introduction of the titanium-containing catalyst component, the downstream distance being equal to at least 25% of the reactor internal diameter.

Further, according to the present invention, an olefin monomer quench in a horizontal reactor comprises means for contacting an olefin monomer or a mixture of olefin monomers with a polymerization catalyst system in the presence of hydrogen in the reactor to form a polymer product. A phase polymerization system is provided, the improvement of which includes a means for introducing the catalyst components of the catalyst system into the top side of the reactor located as close as possible to the upstream end of the reactor, and a cocatalyst plus modifier of the catalyst system. means for introducing the components into the reactor at a distance downstream of the catalyst component introduction means, the downstream distance being equal to at least 25 inches of the reactor internal diameter.

Referring now to the drawings in great detail, FIG.
A reactor 10 is depicted for use in a gas phase polymerization process and apparatus of the type in the methods disclosed in the above cited US patents, such as US Pat. No. 3,965,083.

Such a reactor 10 is elongated with an upstream end 12 and a downstream end 14.
It is generally installed in a horizontal position, as shown in Figure 1.

A shaft 18 extends into the upstream end 14 of the reactor 10 on which a paddle wheel or other type of agitator (not shown and hidden from the figure) is mounted within the reactor 10. These paddle wheels or agitators (not shown) mix the polymeric material, such as polypropylene, within reactor 10 with other materials introduced therein.

As shown, a combination of recycle gas, such as propylene, and hydrogen is fed to a horizontally placed bottom side 1 of a reactor 10.
8 through the injection pipe 20.

A quenching liquid, such as liquid propylene, is then introduced into the horizontal top side 22 of the cylindrical reactor 10 via injection line 24 . The rinsed recirculating gas is injected into the top side of the cylindrical reactor 10, which is still in the horizontal position, through the injection pipe 26 and the valve 28.
It may be introduced through

According to the present invention, a catalyst component such as a supported highly active heterogeneous solid catalyst, for example titanium chloride supported on a magnesium compound, is introduced via an injection line 30 at a location 32 proximate to the upstream end 12 of the reactor 10. Introduce. Upstream end 1
This distance from 2 is shown as Ll in FIG.

The cocatalyst and modifier combination of the catalyst system is then introduced via injection line 34 to the top side of cylindrical reactor 10 at location 36 downstream from location 32 . Typically, distance L2 is a function of the inner diameter of reactor 20.

The titanium-containing components useful in the present invention are generally supported on a hydrocarbon-insoluble magnesium-containing compound in combination with an electron donor compound.

Such supported titanium-containing olefin polymerization catalyst components are typically formed by reacting a titanium GV)-halide, an organic electron donor compound, and a magnesium-containing compound. Optionally, such supported titanium-containing reaction products are further processed or modified by milling or further treatment with additional electron donors or Lewis oxidizing species.

Although the chemical structure of the titanium halide-based magnesium-containing flux components described herein is not presently known, they are preferably comprised of about 1 to about 6 hepatic titanium, about 10 to about 25% by weight. of magnesium, and about 45 to about 65% by weight halogen. Preferred catalyst components made in accordance with the present invention are from about 1 to about 2
% titanium, about 15 to about 21% magnesium, and about 55 to about 65% chlorine.

The supported titanium-containing catalyst component used in the present invention is
They are used in polymerization catalyst systems that include a cocatalyst, including a Group or Group I metal alkyl, and typically one or more modifier compounds.

Useful Group I and Group II metal alkyls have the formula M
is a compound of Rm, where M is a Group II or Group 1A metal, each R is independently an alkyl group having from 1 to about 20 carbon atoms, and m corresponds to the valence of M; . Examples of useful metals M include magnesium, calcium, cadmium, aluminum and gallium. Examples of suitable alkyl groups R include methyl, ethyl, butyl, hexyl, decyl, tetradecyl, and eicosyl.

From the viewpoint of catalyst component performance, preferred group
Group metal alkyls are those of magnesium, zinc, and aluminum, in which the alkyl group is 1
1 to about 12 carbon atoms. Specific examples of such compounds are Mg(CH3)2°Mg(C2Hs)2. Mg
(C2H5) (C4Hg), Mg (C4Hg) 2゜M
g(C6Hta)2. Mg(Ct2H2s)2. Zn
(CHa)z.

Zn(C2H5)2. Zn(C4H9)2. Zn(C4
H9) (C8H1□).

Zn(C6J3)2. zn(c12H25)2. ”
L(CHa)a-AI(C2H5)3. Aft(C3H
7)3. Afl, (C4H9)3゜AI (C6H13)
3 and A4(C1□H25)3. More preferably, magnesium-1 zinc-1 or aluminum-alkyl containing from 1 to about 6 carbon atoms per alkyl group are used. Best results are achieved through the use of trialkylaluminum containing from 1 to about 6 carbons per alkyl group, especially triethyl-aluminum and triisobutylaluminum or combinations thereof.

If desired, metal alkyls with one or more halogen or hydride groups can be used, for example ethylaluminum dichloride 1, diethylaluminum chloride, ethylaluminum sesquichloride, diyne Butyl aluminum hydride 9ride, etc.

Cocatalyst modifiers that may be useful in the polymerization include silanes, mineral acids, organometallic chalcogenide derivatives of hydrogen sulfide, organic acids, organic acid esters, and mixtures thereof.

Organic electron donors useful as cocatalyst modifiers useful in the present invention are organic compounds containing oxygen, silicon, nitrogen, sulfur, and/or phosphorus.

Such compounds include organic acids, organic acid anhydrides, organic acid esters, alcohols, ethers, aldehydes, ketones, silanes, amines, amine oxides, amides, thiols, various phosphoric acid esters and amides, and the like. Mixtures of organic electron donors can be used if desired.

Preferred organic acids and esters are benzoic acid, no-benzoic acid, heptalic acid, isophthalic acid, terephthalic acid, and alkyl esters thereof in which the alkyl group contains from 1 to about 6 atoms, such as methylbenzoic acid, Methylbromobenzoic acid, ethylbenzoic acid, ethylchlorobenzoic acid, butylbenzoic acid, inbutylbenzoic acid, methyl-anisate, ethyl anisate, methyl p-toluate, hexylbenzoic acid, cyclohexylbenzoic acid, and diisobutyl heptatarate. , because they give good results in terms of activity and stereospecificity and are convenient to use.

The above-described catalysts of the present invention are useful in the polymerization of alpha olefins such as ethylene and propylene;
Alpha olefins containing 1 or more than 3 carbon atoms, such as propylene, butene-1% butene-1.
It is most useful in the stereospecific polymerization of 4-methylbontene-1, and hexene-1, and their mixtures with ethylene. The catalysts of this invention are particularly effective in stereospecific polymerizations of propylene or propylene with up to about 20 moles of ethylene or higher alpha olefins. Most preferred is propylene homopolymerization. According to the present invention, highly crystalline polyalphaolefins are made by contacting at least one alpha olefin with the catalyst composition described above under polymerization conditions. Such conditions include polymerization temperature and time, monomer pressure, avoidance of catalyst contamination, selection of polymerization medium during the slurry step, use of additives to control polymer molecular weight, and other conditions well known to those skilled in the art. include. Slurry polymerization, bulk polymerization and gas phase polymerization methods are contemplated here.

The amount of catalyst used will vary depending on the choice of polymerization technique, reactor dimensions, monomers to be polymerized, and other factors known to those skilled in the art, and can be determined based on the examples provided below. Typically, the catalyst of the present invention is used in amounts ranging from about 0.2 to 0.05 milligrams of catalyst per II of polymer product.

Regardless of the polymerization method used, the polymerization should be carried out at a sufficiently high temperature to ensure adequate polymerization rates and avoid unduly long reactor residence times. Generally, temperatures in the range of about 0°C to 120°C are preferred, and temperatures of about 20°C to about 95°C are preferred for adult fish to obtain good catalytic performance and high production rates. More preferably, the polymerization according to the invention is carried out from about 50°C to about 90°C.
It is carried out at a temperature in the range of °C.

Alpha olefin polymerizations according to the present invention are carried out at monomer pressures of about atmospheric pressure or greater. Generally, the 7-summer pressure is in the range of about 20 to about 600 psi, with the exception that in gas phase polymerizations the 7-summer pressure should be less than or equal to the vapor pressure at the polymerization temperature of the alpha olefin being polymerized.

The washed gas to be recycled is passed through the horizontally viewed reactor 10.
may be introduced at a position 38 downstream from position 36 by a distance L3 into the top side 22 of.

The powdered polymer product is then withdrawn through an outlet 40 adjacent to the interior 14 of the reactor 10 as shown.

According to the teachings of the present invention, the distance L2 between the catalyst component introduction point 32 and the catalyst plus modifier introduction point 36 downstream of the catalyst introduction point 32 is equal to at least 25% of the diameter of the reactor.

With this arrangement for the catalyst introduction position and the catalyst plus modifier introduction position, the catalyst is mixed with the 4-limer material inside the reactor 10 and the point of catalytic reaction with the catalyst plus modifier is delayed. The catalyst is gradually activated when mixed with the polymer, thus reducing sudden polymerization and polymer lump formation when the catalyst and catalyst plus modifier are introduced into the reactor adjacent to each other.

Experimental tests have shown that the larger the distance L2, the less polymer agglomerates are deposited in the reactor 10 and the less agglomerates are found in the powdered polymer product withdrawn from the outlet 40. .

However, it is expected that the generation of polymer product within the reactor and the length of the reactor will place a limit on distance L2.

In this regard, 1, if the catalyst plus modifier is reactor 1
If introduced adjacent to the downstream end 14 of 0, the extreme lag in catalyst activation will reduce the utilization of the reactor volume in order to produce the polymer product withdrawn from the outlet 40. It will make you feel bad.

Experimental tests conducted with the distance AiL2 varied between 17% and 130% of the reactor internal diameter showed that the preferred distance as no centage of the reactor internal diameter was 3% of the reactor internal diameter.
It shows that it is between 0% and 80ch.

Below are the working variables of some experimental tests or examples carried out with various lengths L2.

Example 1 In this example, a reactor 10 of the type used in the process disclosed in U.S. Pat. No. 3,965,083 was used.
It was used.

Reactor temperature, F 160 Reactor pressure, psig 300 Distance 19 Example ■ Test time 7 days Reactor temperature, F 160 Reactor pressure, psig 300 Distance 130 Example ■ In another test, the inner diameter was 16- Polypropylene was polymerized in a continuous reactor 10 approximately 48-inches long. The powder bed within the reactor occupied approximately 40 inches of reactor volume. The catalyst was the same as used in Examples 1 and 2, the polymerization was carried out at 160 T and 300 psig pressure, and the stirrer was operated at a speed of 45 rpm. Catalyst/hexane slurry (0,0326g/C
(at a concentration of C) was stored in a 2 gallon autoclave vessel and injected into the reactor in an intermittent manner through a 10 foot length of 1 inch tubing. During the polymerization reaction, the catalyst and cocatalyst/modifier were injected by placing the catalyst injection nozzle downstream of the cocatalyst/modifier injection nozzle.

Other variables and resulting polymer mass formation were as follows.

Variable Value of the variable Distance between the nozzles, inches 27 Distance as the inner diameter 17 Polymer agglomerates as the produced powder 0.21 Example ■ In this fourth example, we use the basics given in Example ■ parameters were used, but the catalyst injection nozzle was placed upstream of the cocatalyst/modifier nozzle, and their operating conditions were as follows:

Distance as part of internal diameter 42 Polymer lumps as part of produced powder 0.016 Formation of polymer lumps in a horizontally arranged cylindrical reactor for gas phase polymerization, e.g. It is understandable that this is not desirable when used, since known operational difficulties occur within the reactor 10 in downstream equipment. Agglomerates also result in loss of polymer and catalyst material. In addition, the formation of severe polymer agglomerates leads to costly shutdowns of the production equipment (interruption of reactor 10). Therefore, prevention or at least minimization of polymer lump formation is essential in the use of highly active catalyst systems.

The present invention provides for injection of the cocatalyst plus modifier component into the reactor at least 25 mm downstream of the point of catalyst component injection into the reactor.
The discovery that positioning at a distance equal to % greatly reduces the formation of polymer lumps [thus solving the lump formation problem]. It has also been discovered in accordance with the teachings of the present invention that such distance should preferably be between 30% and 80 inches of the reactor inner diameter. On top of that,
It is important that the catalyst is injected into the reactor 10 at a location upstream of the cocatalyst/modifier injection nozzle.

From the foregoing description, it will be appreciated that the method and apparatus of the present invention provide numerous advantages, some of which are described above, and which are also unique. In particular, the critical separation of the injection locations of catalyst and cocatalyst plus modifier into the horizontal cylindrical reactor minimizes, if not completely avoids, the formation of polymer agglomerates.

It is also envisioned that modifications may be made to the method and apparatus of the invention without departing from the teachings of the invention. Accordingly, the scope of the invention is limited only as required by the claims.

[Brief explanation of drawings]

FIG. 1 is a side view of a quenched gas phase olefin polymerization reactor constructed in accordance with the present invention. (5 other people)

Claims (1)

Claims: 1) A process for producing olefin monomers in a horizontal reactor comprising: 1) contacting an olefin monomer or a mixture of olefin monomers with a polymerization catalyst system in the reactor in the presence of hydrogen to form a polymer product; In the quenched gas phase polymerization method,
The titanium-containing catalyst component of the catalyst system is introduced to the top of the reactor as close as possible to the upstream end of the reactor, the catalyst is mixed with the polymer product in the reactor, and the cocatalyst and modifier components of the catalyst system are A process comprising introducing the catalyst at a distance downstream of the point of introduction into the top side of the reactor, the downstream distance being equal to at least 25% of the internal diameter of the reactor. 2) A method according to claim 1, wherein the downstream distance is equal to 30% of the reactor internal diameter. 3) A method according to claim 1, wherein the downstream distance is equal to 80% of the reactor internal diameter. 4) In an apparatus for the quench gas phase polymerization of olefin monomers in a horizontal reactor comprising means for contacting the olefin monomer or olefin monomer mixture with a polymerization catalyst system in the reactor in the presence of hydrogen to form a polymer product. , means for introducing a titanium-containing catalyst component of the catalyst system into the top side of the reactor at a location adjacent to the upstream end of the reactor;
and means for introducing the cocatalyst and modifier components of the catalyst system into the reactor located a distance downstream of the means for introducing the titanium-containing catalyst component, the downstream distance being equal to at least 25% of the reactor internal diameter. A device characterized by: