KR820002026B1 - Exothermic polymerization in a vertical fluid bed reactor system containing cooling means therein - Google Patents

Abstract

Olefin polymers are manufd. in vertical fluidized bed reactors of uniform diam. and variable bed height contg. an indirect cooler. The reactor is operated without a velocity redn. zone or a cyclone to sep. fine particles from the gas. Thus, ethylene was copolymd. with 1-butene or propylene in a 26.5ft tall fluidized-bed reactor with inner diam. 13.5 in. contg. an internal cooler consisting of 4 vertical loops 4ft long of 1 in. diam. stainless steel tubing through which tempered water was passed. The catalyst used was a high activity Cr- and(or) Ti-contg. catalyst.

Description

Process for producing solid particulate polymer during continuous exothermic polymerization in a vertical fluidized bed reactor system with cooling means

The accompanying drawings show a vertical fluidized bed having an internal cooler (10: reactor, 12: reaction zone, 14: transport separation zone, 16: gas analyzer, 20: distribution plate, 40: separation zone, 50: cooling tube) Figure showing the system.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the preparation of a solid particulate polymer by a continuous low pressure gas phase method during an exothermic polymerization reaction in a vertical, uniform diameter fluidized bed reactor system, comprising a gas upstream and a polymerization catalyst containing at least one polymerizable monomer. The method relates to a process for producing a continuous low pressure gas phase of a solid particulate polymer, which comprises supplying to a fluidized bed of polymer particles, removing exotherm of the reaction by indirect cooling means in the reactor, and taking out the dry particulate polymer.

US Pat. Nos. 4,011,382 and 4,003,712 describe gas phase fluidized bed processes for preparing olefin polymers in the presence of highly active catalysts. In particular, US Pat. No. 4,011,382 uses a fluidized bed process under specific operating conditions with a catalyst that optionally contains chromium or titanium (and optionally fluorine) to provide a low density polyethylene by solvent-free gas phase process under pressures up to 1000 psi. It is described that this can be produced commercially.

The fluidized bed reactor described in this patent preferably has a cylindrical vertical portion at the bottom and a reduction zone as a horizontal portion larger than the bottom.

Gas streams that do not react in the fluidized bed in the fluidization process constitute a recycle stream, which is removed from the polymerization zone by passing through a deceleration zone located above the bed. The slowdown reduces the rate of recirculation and causes particles to fall back into the bed. Cyclone is used to assist in the removal of particles from the recycle stream. Reducers and cyclones are used to prevent fine particles from joining and accumulating in the gas entering the recirculator, thereby clogging the heat exchanger. The upper deceleration (horizontal section) and the lower phase in the fluidized bed reactor are connected to the conveying section with an inclined wall. When using such a fluidized bed reactor, the gas is introduced into the polymerization zone at the bottom, and fine particles separated from the recycle stream in the deceleration zone are dropped on the inclined wall of the transport site. These fine particles accumulate for a while. Since these fine particles contain an active catalyst, they react with the monomers in the stream to be recycled to form a solid sheet and then grow until they block the flow of the recycled gas or slide down to the sloping wall of the transport site to polymerize. You will enter.

In the polymerization zone, the flakes block the flow of gas on the flakes in some of the phases in the polymerization zone, reducing fluidization, and because the gas cannot be used to remove heat well from the polymer particles, the particles fuse to the fluidization zone. Therefore, if the reaction is not stopped or the flakes are not removed, a large piece of polymer is formed which can lower the entire polymerization zone. In order to minimize the formation of such flakes on the inclined walls of the transport site, it is necessary to operate the bottom surface of the transport site or the upper surface of the fluidized bed immediately below with the reactor.

This operation causes bubbles to burst on the surface of the fluidized bed, which removes reactive fine particles from the inclined wall and returns to the fluidized bed, causing larger particles to fall from the fluidized bed to the inclined wall of the carrier. This operation must be done in a constant fluidized bed and prevents a reduction in the speed of transportation or start-up.

U.S. Patent No. 3,298,792 describes minimizing the formation of flakes on sloped walls in a fluidized bed, ie a vertically positioned scraper is operated by the operating side to remove particles attached to the wall.

This technique works well in small fluidized bed reactors according to the examples but is very difficult if not impossible in practice in large reactors on a commercial scale. The fluidized bed of this patent is conical in which the diameter of the reactor bottom is smaller than the diameter of the top. The reactor thus has all sloped walls at the fluidized bed site and at the deceleration site for the polymerization zone and the polymerization site. The vertically located scraper removes particles adhering to the walls of the polymerization zone and the reducer. Methods of shaking the vertical fluidized bed and / or removing particles adhering to the walls of the reactor are described, for example, in US Pat. Nos. 3,300,457 and 4,012,573.

It has been found that the fluidized bed polymerization reactor can be operated without a decelerator and that the use of a cyclone to separate fine particles from the gas is advantageous in many ways. The biggest advantage is that the flakes that form on the inclined walls of the carriage are removed. This reduces the frequency of stopping the reactor to remove the flakes. The second advantage is that the depth of the bed in the polymerization zone can be greatly changed, which can greatly increase the range of the outlet of the reactor. Changes in bed depth allow for minimal contamination when the product is prepared from other novel products. This minimizes the height of the phase before changing the product and maintains this position until the product becomes a new product. The production rate per unit dose of the phase used (Lb / ft ³ ) is generally increased when the product changes at the reduced phase position, because the system's heat removal capacity and product discharge capacity are normally adjusted to normal Because there is. Therefore, the change time and the volume of the resin produced during the change are reduced.

Another advantage of a uniform diameter reactor is that it requires a small size to start continuously the powder material initially charged without flake formation. The cost of assembling the fluidized bed without the huge horizontal speed reducer is practically reduced because the large diameter and the inclined surfaces of the transport are not required.

Operating without a speed reducer, cyclone or filter results in a 100 to 1000-fold increase in confluent particles. Increasing the concentration of particles in the recirculation stream will cause microparticles to accumulate in the recirculation pipe and the upper and lower distribution boards, preventing the reactor from operating. Moreover, these particles may wear the compressor or accumulate in the moving parts of the compressor, preventing the compressor from operating. It was expected to prevent. Unexpectedly, however, it was found that the accumulation of particles in the recirculation pipe and the distribution board would not be a problem if the speed at all parts of the recirculation pipe is kept high and the recirculation device is designed to have a low speed or a minimum stop. It has also been found that the accumulation of particles in the moving parts of the compressor is minimized to a degree that does not affect operation and effectiveness, so that the compressor is not worn. However, fine particles accumulated rapidly on the heat exchanger.

The accumulation of particles on the heat exchanger can be prevented by installing a so-called cooler in the fluidized bed itself, but since the gas is used as the heat transfer medium of the external cooler, to prevent large quantities of solids from entering the recycled gas from the hot fluidized bed. The reaction rate is limited by the velocity of the gas to maintain a sufficiently low temperature. The internal cooler removes the heat of reaction directly from the solid particles and the gas velocity is very slow enough to use less energy. Furthermore, since the removal of heat is independent of the flow rate of the gas, the pressure in the reactor can also be reduced to the limit by the polymerization kinetics. Mounting the cooling tube vertically on the fluidized bed of the present invention prevents large bubbles from agglomerating and thus improves the quality of fluidization. Bubbles tend to elevate in the fluidized bed if they agglomerate, so the gas is drawn from the edge of the bed to the center, reducing the mixing ability of the wall poles, resulting in a non-uniform phase. The vertical tube acting as a baffle prevents bubbles from moving to the center of the phase, increasing the mixing capacity near the wall.

The use of an external cooler in the gas phase flow makes the gas entering the bottom of the bed cooler than the bed itself. Since the physical properties of the polymers produced by these catalysts are temperature sensitive, a cold bottom of the phase results in a synthesis of different physical properties. When these particles are mixed with the rest of the phase, the molecular weight distribution of the polymer is widened. The use of an internal cooler removes heat from the polymer itself, so that the temperature of the incoming fluidizing gas is the same throughout the fluidized bed.

Another problem with the use of an external cooler is that low molecular weight oligomers are formed during the polymerization process, which are volatile at the temperature of the reactor and are therefore condensed on the cold surface of the external cooler to attach fine particles to the heat transfer. Furthermore, when preparing olefin polymers using relatively high boiling comonomers, these monomers can also condense in the external cooler and cause plugging of the heat exchanger. This condensation does not occur when using an internal cooler because the temperature of the recirculation device is the same as the temperature of the reactor.

The inventors have found that a relatively low pressure gas phase process is employed when at least one polymerizable monomer is polymerized or copolymerized in a constant diameter, vertical fluidized bed reactor containing a cooler to remove heat of reaction in the reactor in the presence of a polymerization catalyst. It has been found that commercial polymers or copolymers with low content of catalyst residues can be prepared.

It is an object of the present invention to operate polymers, in particular olefin polymers, by using an indirect internal cooler to remove heat generated by polymerization in a fluidized bed and by using a vertical fluidized bed reactor of constant diameter and adjustable bed height. It is provided by an improved reactor system with continuity.

1. Olefin Polymer

The olefin polymer produced by the technique of the present invention is a solid material. The ethylene polymer has a density of 0.91 to 0.97 and a melting rate of 0.1 to 100 or more.

The olefin polymers prepared herein are prepared by homopolymerizing or copolymerizing one or more alpha olefins containing from 2 to 12 carbon atoms. Other alpha-olefin monomers are mono-olefins or nonconjugated di-olefins.

Polymerizable mono-alpha-olefins include ethylene, propylene, butene-1, pentene-1,3-methylbutene-1, hexene-1,4-methyl-pentene-1,3-ethylbutene-1, heptene-1 , Octene-1, deken-1, 4,4-dimethylpentene-1 ,, 4,4-dimethylhexene-1,3,4-dimethylhexene-1,4-butyl-1-octene, 5-ethyl-1 -Dekene, 3,3-dimethylbutene-1, and the like. Diolefins that can be used include 1,5-hexadiene, dicyclopentadiene, ethylidene norbornene and other nonconjugated diolefins.

2. High activity catalyst

The catalyst used in the present invention is a catalyst containing a highly active transition metal, preferably chromium and / or titanium. Highly active catalysts are those capable of producing at least 50,000, preferably at least 100,000 polymers per pound of transition metal in the catalyst. This is because gas phase fluidized bed processes generally do not use a process for removing catalyst residues. Thus, by reducing the amount of catalyst residue in the polymer, the resin granulator and / or the final consumer should have no problem when using the dipolymer. It is important that the catalyst residues be low in the case of catalysts made of chlorine-containing materials such as chlorides of titanium, magnesium and / or aluminum, such as so-called Ziegler or Ziegler-Natta catalysts. If there is much residual chlorine in the molding resin, it will cause fitting and corrosion on the metal surface of the molding apparatus.

The catalysts containing the highly active transition metals actually used in the present invention are as follows.

(I) The silyl chromates described in US Pat. Nos. 3,324,101 and 3,324,095 were used as reference.

The silica chromate catalyst is characterized by comprising a group of the following general formula.

R is a hydrocarbyl group having 1 to 14 carbon atoms. Preferred silylchromate catalysts are bis-triarylsilyl chromates and bistriphenylsilyl chromates are best.

This catalyst is used on supports such as silica, alumina, toria, zirconia and carbon black, microcrystalline cellulose and unsulfonated ion exchange resins.

(II) Bis (cyclopentadienyl) chromium (II) compounds described in US Pat. No. 3,879,368 were used as reference.

_Wherein R 'and R''are the same as or different from each other and are C ₁ to C _2o hydrocarbon groups and n' and n '' are the same or different integers from 0 to 5. R 'and R''hydrocarbon groups are saturated or unsaturated groups and are aliphatic, cycloaliphatic and aromatic groups such as methyl, ethyl, propyl, butyl, pentyl, cyclopentyl, cyclohexyl, allyl, phenyl and naphthyl groups.

These catalysts are used on a support as above.

(III) The catalyst described in US Pat. No. 4,011,382 was used as reference. These catalysts contain chromium and titanium in the form of oxides and optionally include fluorine and a support. The catalyst is 0.05 to 3.0, preferably 0.2 to 1.0% by weight of chromium (calculated as Cr), about 1.5 to 0.9, preferably 4.0 to 7.0% by weight, based on the total weight of the support and the chromium, titanium and fluorine Titanium (calculated as Ti) and 0.0 to 2.5, preferably 0.1 to 1.0% by weight of fluorine (calculated as F).

Among the chromium compounds that can be used are chromium compounds which are oxidizable with CrO ₃ or CrO ₃ under the activation conditions used. At least a portion of the chromium in the supported and activated catalyst must be hexavalent. Chromium compounds that can be used in addition to CrO ₃ are described in US Pat. Nos. 2,825,721 and 3,622,521, the contents of which are incorporated herein by reference, including chromic acetyl acetonate, chromic nitrate, chromic acetate, chromic Chloride, chromium sulfate and ammonium chromate.

Water-soluble chromium compounds such as CrO ₃ are suitable for arranging on a support in solution. Chromium soluble in organic solvents can also be used.

Titanium compounds that can be used include all titanium compounds that are oxidizable to TiO ₂ under the activation conditions used and are described in US Pat. No. 3,622,521 and Dutch Patent Application No. 72-10881 (see the contents of this publication).

These compounds include the following general formula.

(R) _n Ti (OR ') _m and (RO) _m Ti (OR') _n

Wherein m is 1,2,3 or 4 and n is 0,1,2 or 3 and m + n = 4,

TiX ₄

Wherein R is a C ₁ to C ₁₂ alkyl, aryl or cycloalkyl group and combinations thereof, such as aralkyl, alkaryl and the like.

R 'is R cyclopentadienyl and a C ₂ to C ₁₂ alkenyl group (ethenyl, propenyl, isopropenyl, butenyl, etc.).

X is chlorine, bromine, fluorine or iodine.

Therefore, these titanium compounds include titanium tetrachloride, titanium tetraisopropoxide and titanium tetrabutoxide. These titanium compounds can be easily dissolved in a hydrocarbon solvent and arranged on a support.

Titanium (as Ti) is present in the catalyst in a molar ratio of 0.5 to 180, preferably 4 to 35, by chromium (as Cr).

Usable fluorine compounds are HF or any fluorine compound capable of producing HF under the activation conditions used. Besides HF, available fluorine compounds are described in Dutch Patent Application No. 72-10881. This compound includes ammonium hexafluorosilicate, ammonium tetrafluoroborate and ammonium hexafluorotitanate. These fluorine compounds can be easily arranged on the support in the form of an aqueous solution and dry mixed with other components of the catalyst and the solid fluorine compound prior to activation.

The inorganic oxide material that can be used as a support in the catalyst composition is a porous material having a large surface area, that is, a surface area of 50 to 100 m ² / g, an average particle size of 50 to 200 microns, and comparable to silica, alumina, toria, zirconia, and the like. Other inorganic oxides and mixtures thereof.

Catalyst supports in which chromium and / or fluorine are arranged should be dried before contact with the titanium compound. Drying is usually carried out by simply heating the catalyst support or drying a dry inert gas or dry air before use. The drying temperature was found to have a great influence on the molecular weight distribution and dissolution rate of the resulting polymer. Preferred drying temperatures are between 100 and 300 ° C.

The supported catalyst can be activated near the sintering temperature of this catalyst. Passing dry air or oxygen through the supported catalyst during activation assists the potential of water from the support. When well-dried air or oxygen is used, activation for about 6 hours at 300 to 900 ° C. is sufficient, and this temperature should not be too high to prevent sintering of the support.

(IV) The invention entitled "Preparation of Ethylene Copolymers in Fluidized Bed Reactors," filed on March 1, 1978 under the name of F. J. Carroll, et al., Described in US Pat. The catalyst is prepared from a precursor composition consisting of at least one titanium compound, at least one magnesium compound, at least one electron donor compound, at least one activator compound and at least one inert carrier material.

The titanium compound has the following general formula.

Ti (OR) _a X _b

In the alban formula

R represents a C ₁ to C ₁₄ aliphatic or aromatic hydrocarbon group or COR '(R' is a C ₁ to C ₁₄ aliphatic or aromatic hydrocarbon group).

X is selected from C ₁ , Br, I or mixtures thereof and a is 0, 1 or 2, b is 1 to 4 and a + b = 3 or 4.

Titanium compounds are used alone or in combination, and include TiCl ₃ , TiCl ₄ , Ti (OC ₆ H ₅ ) Cl ₃ , Ti (OCOCH ₃ ) CI ₃ and Ti (OCOC ₆ H ₅ ) Cl ₃ .

Magnesium compound has the following general formula.

MgX ₂

Wherein X is selected from Cl, Br, I or mixtures thereof. These magnesium compounds are used alone or in combination and include Mgcl ₂ , MgBr ₂ and MgI ₂ , and anhydrous MgCl ₂ is a particularly preferred magnesium compound.

In preparing the catalyst required for the present invention, 0.5 to 56, preferably 1 to 10 moles of magnesium compound per mole of titanium compound is used.

Titanium compounds and magnesium compounds are used in the form of being easily soluble in the electron donor.

The electron donor is an organic compound that is liquid at 25 ° C. and the titanium compound and magnesium compound are partially or completely dissolved. Electron donors are known per se or as bases of Lewis.

Electron donors include compounds such as alkyl esters of aliphatic and aromatic carboxylic acids, aliphatic ethers, cyclic ethers and aliphatic ketones. Preferred among these electron donors are alkyl esters of C ₁ to C ₄ saturated aliphatic carboxylic acids; Alkyl esters of aromatic carboxylic acids of C ₇ to C ₈ ; Aliphatic ethers of C ₂ to C ₈ and preferably C ₃ to C ₄ ; C ₃ to C ₄ cyclic ethers and preferably C ₄ cyclic mono or diethers; Aliphatic ketones of C ₃ to C ₆ and preferably C ₃ to C ₄ . Most preferred of these electron donors include methyl formate, ethyl acetate, butyl acetate, ethyl ether, hexyl ether, tetrahydrofuran, dioxane, acetone and methylisobutyl ketone.

The electron donor may be used alone or in combination thereof.

2 to 85 moles, preferably 3 to 10 moles, of electron donors are used per mole of titanium.

The activator compound has the following general formula.

Al (R '') c X ' _d He

In the above general formula

X 'is Cl or OR' ''

R '' and R '''are the same or different and are C ₁ to C ₁₄ saturated hydrocarbon groups

d is 0 to 1.5

e is 1 or 0

c + d + e = 3.

The activator compound may be used alone or in combination thereof and may be AL (C ₂ H ₅ ) ₃ , AI (C ₂ H ₅ ) ₂ CI, Al (iC ₄ H ₉ ) ₃ , Al (C ₂ H ₅ ) ₂ H , Al ₂ (C ₂ H ₅ ) ₃ CI ₃ , Al (iC ₂ H ₉ ) ₂ H, AI (C ₂ H ₅ ) ₃ CI ₃ , AL (C ₆ H ₁₃ ) ₃ , AI (C ₈ H ₇ ) ₃ , and Al (C ₂ H ₅ ) ₂ (OC ₂ H ₅ ), and the like.

In the activation of the catalyst used in the present invention, 10 to 400 moles, preferably 10 to 100 moles of activator compound per mole of titanium are used.

The carrier material is a solid particulate material and is inert to the components of other catalyst compositions and the active components of other reaction systems. These solid carriers include inorganic materials such as oxides and molecular sieves of silicon and aluminum and organic materials such as olefin polymers (eg polyethylene polymers). The carrier material is used in the form of a dry powder having an average particle size of 10 to 250, preferably 50 to 150 microns. This material is also preferably porous and has a surface area of at least 3, preferably at least 50 m ² / g. This carrier material must be dehydrated. This is usually done by heating or predrying the carrier material with a dry inert gas before use. Inert carriers are also treated with one to eight percent by weight of one or more aluminum alkyl compounds for further activation.

3. Fluidized bed reaction system

The flow reactor system used in the present invention will be described with the drawings. In FIG. 1, the reactor 10 is capable of polymerizing the formed polymer particles and a small amount of catalyst particles and growing polymer particles which are fluidized by continuously introducing a modified gas component in the form of a gas that is supplemented and recycled through the reaction zone. It consists of the reaction zone 12 comprised of the phases which do. In order to maintain a growing phase, a large amount of gas flow through the bed must be above the minimum rate required for fluidization, preferably 1.5 to 10 times less than Gmf, and 2 to 6 times better than Gmf. Gmf is an abbreviation for the minimum amount of gas flow required to achieve fluidization. Why. Pigtails and wai. H. C. Y. Wen and Y. H. Yu, Mechanics of Fluidization, Chemical Eigineering Progress Symposium Series, 62,100-111 (1966).

It is essential that the phase always contain particles to prevent the formation of locally "hot spots" and to introduce and distribute catalyst particles throughout the reaction zone. At start-up, the reaction zone must be filled with a bed of granulated polymer particles before starting gas flow. These particles have the same or different properties as the polymer to be formed. When the properties are different, they are recovered as the first product with the desired polymer particles. Sometimes the fluidized bed of the desired polymer particles is substituted for the starting phase.

Partially or wholly activated precursor compounds (catalysts) used in the fluidized bed are preferably stored in reservoir 32 under a blanket of gas that is inert to the reservoir, such as nitrogen or argon.

Fluidization can be achieved by increasing the gas recirculation and passage rate, typically about 50 times the feed rate of the make-up gas. Dense masses of growable particles, which are created by gas infiltration into the fluidized bed, are generally present in the fluidized bed. The overall pressure drop in the phase depends on the gravity of the reactor as it is equal to or slightly larger than the mass of the phase divided by the horizontal part.

The make-up gas should be at least equal to the recovery rate of the polymerized particles in the reactor. The composition of the make-up gas is measured by the gas analyzer 16 located above. The gas analyzer, which measures the composition of the recycle gas and make-up gas, controls the gas composition to remain steady within the reaction zone.

To complete the fluidization, a recycle gas and, if desired, a portion of the make-up gas is returned to the reactor at point 18 below the bed. There is a gas distribution plate 20 on the point that is returned to assist the fluidized bed.

The gaseous fraction that does not react in the phase consists of recycled gas recovered from the polymerization zone through a disengaging portion 14 located above the phase where particles can fall back into the phase.

The recycle gas is compressed by the compressor 25 and returned to the reactor. Reactor 10 includes an internal cooler consisting of tubes 50, located in the fluidized bed, through which heat of reaction is removed. Although the internal cooler is shown as a bear tube in the figure, it is also used as a vertical tube or a plate-shaped coil.

The temperature of the resin in the bed is adjusted as necessary to maintain the temperature of the bed at a constant temperature by controlling the temperature and / or flow rate of the coolant entering the internal cooler.

Since the reaction heat is always removed, there is no noticeable temperature change in the phase. Since the recycle gas is not cooled, the temperature of the gas entering the fluidized bed 12 through the distribution plate 20 is essentially the same as the temperature of the recycle gas leaving through the delivery glass section 14.

The distribution plate 20 plays an important role in the operation of the reactor. Fluidized beds include polymeric particles and catalyst particles that are growing or formed. Since the polymer particles are hot and active, they should not be cured in the presence of less active materials, and the active catalyst contained in them should continue to react to prevent fusion. Therefore, it is important to pass the recycle gas at a rate sufficient to maintain fluidization in the bed. The distribution plate 20 is used for this purpose and includes a screen, an inclined plate, a perforated plate, a bubble cap type plate, and the like. The components of this plate may be all stationary or in moving form as described in US Pat. No. 3,298,792. Whatever the design, the distribution plate distributes the recycle gas to the particles at the bottom of the bed to maintain fluidization conditions and, if the reactor is not in operation, to support the phase of less active resin particles.

In the polymerization reaction of the present invention, hydrogen is used to control the molecular weight. The ratio of hydrogen / ethylene used is varied in the range of 0 to 2.0 moles of hydrogen per mole of monomer in the gas fraction.

Any gas inert to the catalyst and reactants may be present in the gaseous fraction. The activator compound is preferably added to the reactor in the recycle tube. The activator is thus fed from the injector 27 through the tube 27A into the gas recycler.

It is essential to operate the fluidized bed reactor below the melting temperature of the polymer particles. To prevent fusion, the operating temperature should be below the fusion temperature.

In order to prepare the ethylene copolymer by the process of the present invention, the operating temperature is preferably 30 to 125 ° C, and 75 to 115 ° C is the best.

The fluidized bed reactor is operated at a pressure of up to 1000 psi, preferably from 50 to 350 psi.

The partially or fully activated precursor composition (catalyst) is injected at point 30 located above the distribution plate 20 at the same rate as the rate of consumption of the phase. Preferably it is injected from the top of 1/4 to 3/4 of the phase. Injection of the catalyst at points on the distribution plate is an important aspect of the present invention.

Since the catalyst used in the present invention has high activity, it assists in distributing the activated catalyst generally to the area under the distribution plate, and forms a very hot spot in the bed so that a "hot spot" is formed. It prevents you from doing it.

Gases that are inert to the catalyst, such as nitrogen or argon, carry partially or fully reduced precursor compositions and added activator compounds or necessary non-gas modifiers into the bed.

The rate of bed production can be controlled by the rate of catalyst injection. The production rate is increased by simply increasing the catalyst injection rate and decreasing by decreasing the catalyst injection rate.

The rate of release of the reaction heat varies with varying the rate of injection of the catalyst, thereby controlling the rate of heat release by increasing or decreasing the temperature and / or flow rate of the coolant in the internal cooler. This keeps the temperature of the phase at constant temperature. In order to properly control the temperature and / or flow rate of the coolant, it is necessary to fully mechanize the fluidized bed and internal cooler to detect the temperature change of the bed.

Under a given operating condition, it is essential that the phase is pulled at a rate equal to the rate at which the particulate polymer product is formed and maintained at a constant height. Since the rate of heat release is directly related to the rate of product formation, the temperature rise of the coolant through the reactor (the difference between the temperature at injection and the temperature at discharge) can be determined by measuring the rate at which the particulate polymer is formed under a constant rate of coolant. have.

The granulated polymer particles can be conveniently and preferably drawn out by the continuous operation of the valves 36 and 38, the separator 40 in time. When the valve 38 is closed, gas is discharged through the pipe 51. The valve 38 opens and the product is conveyed to an external recovery stand. The valve 38 closes again and waits for the next recovery process.

Finally, a suitable discharge device is provided in the fluidized bed reactor to create an outlet for starting and braking the bed. The reactor does not require an agitator and / or scraping device.

The active highly supported catalyst systems described herein produce fluidized bed products having an average particle size of 100 to 1500 microns, preferably 500 to 1000 microns.

For good operation, a chiller must be included within the fluidized bed portion of the reactor 10. When the chiller expands below or above the fluidized bed, the particles settle on a non-vertical surface, and the particles contain an active catalyst, which grows larger, forming large pieces of solid polymer, which hinders the operation of the reactor.

The chiller in the reactor uses a cooler or a heat exchanger. The design of the chiller should not reduce the free cross-sectional area of the chiller's cross-sectional area, thereby avoiding localized areas where the face velocity is more than 10 times the minimum flow rate. The flowable cross section at the largest cross section of the internal cooler is the minimum free cross section.

The reactor shown in FIG. 1 can be operated in a range of diameter to height ratio of 1: 1 to 1:10. The minimum depth of the fluidized bed depends on the shape of the distribution plate and the size of the bubbles, regardless of the diameter of the reactor, as long as the transfer liberation height has a complex functional relationship with particle size distribution, gas velocity, particle density, and gas density. The height of the delivery glass area is F. a. F.A. Zenz and D.F.Othmer, "Fluidization and Fluid Particle Systems", Reinhald Publishing Corp. 1960, pp 374-387.

EXAMPLE

The properties of the polymers in the examples are determined by the following test methods.

Density: For materials with a density of 0.940 or less, use the ASTM 1505 method to achieve a crystalline equilibrium at 110 ° C for 1 hour. A modified method is used for materials with a density greater than 0.940, where the test plaques are brought to 120 ° C for 1 hour to reach crystalline equilibrium and then quickly cooled to room temperature. All density values are expressed in g / cm ³ and the density measurement is by density gradient column.

Melting rate (MI): measured in ASTM D-1238-Condition E-l90 ° C and expressed in g every 10 minutes.

Flow Rate (HLMI): ASTM D-1238-Condition F- Measured 10 times the weight used in the melt rate test.

Bulk Density: Pour the resin into a 100 mil graduated cylinder up to 100 mils without weighing the cylinder through a 3/8 '' diameter funnel.

Space and yield per hour: Pounds of resin produced per hr per ft ^{3 of} upper shell

[Catalyst Preparation Method]

[Catalyst A]

To a solution of the desired amount of CrO ₃ in 31 dilute water is added 500 g of a porous silica support having an average particle size of about 70 microns and a surface area of about 300 m ² / g. The mixture of support and water is stirred, left for 15 minutes and filtered to remove about 2200 to 2300 ml of solution.

The silica impregnated with CrO ₃ is dried at 200 ° C. for about 4 hours in the presence of a nitrogen fraction. 400 g of supported CrO ₃ is slurried in about 2000 ml of dried isopentane and the desired amount of tetraisopropyl titanate is added to this slurry. This is mixed thoroughly and isopentane is dried by heating the reactor.

The dried material is transferred to an activator (heating vessel) and mixed with an appropriate amount of (NH ₄ ) ₂ SiF ₆ . The mixture is heated at 50 ° C. in the presence of N ₂ and then heated at 150 ° C. for 1 hour to remove isopentane and the organic residue slowly from the tetraisopropyl titanate (be careful of the fire).

The catalyst is activated for 2 hours at 300 ° C and again at 825 ° C for 8 hours using dry air instead of N ₂ fraction. The activated catalyst is cooled to 150 ° C. by adding dry air (at ambient temperature) and again by adding N ₂ (at ambient temperature) to room temperature.

The amount of chromium, titanium and fluorine compounds in the activated catalyst is as follows.

[Catalyst B]

2000 g of porous silica support having an average particle size of about 70 microns and a surface area of about 300 m ² / g are dehydrated in an activator (heating vessel). The silica is heated to 400 ° C. for 2 hours and then to 600 ° C. for 8 hours. Dehydrated silica is added to dry N ₂ , cooled to room temperature and stored in the presence of N ₂ . 462 g of dehydrated silica is slurried in 4000 ml of isopentane dried at 70 ° C. and 350 ml of 15% by weight bis- (cyclopentadienyl) chromium II, ie chromosene in toluene, is added and stirred in a sealed vessel for 1 hour. . Therefore isopentane does not break. In the 90 ℃ for 30 hours, the catalyst will be discharged by N ₂ dried and stored under N ₂ exist. The final catalyst contains 6% by weight chromosene.

[Catalyst C]

Catalyst C is prepared by adding 1000 g of dehydrated silica to 5500 ml of dry isopentane at 45 ° C. The slurry was stirred for 30 minutes and then added to 30 g of bis-triphenylsilyl chromate and stirring continued for 10 hours. 200 ml of a 20% by weight solution of diethylaluminum ethoxide dissolved in the nucleic acid is added for 30 minutes, followed by stirring for 4 hours, and the liquid is decanted from the catalyst. After stirring again the catalyst is dried for 24 h at 70 ° C. with a slight N ₂ discharge and stored in the presence of N ₂ . The final catalyst contains 3% by weight bis-triphenylsilyl chromate with an Al / Cr molar ratio of about 6: 1.

[Catalyst D]

1. Method of manufacturing submerged precursor

41.8 g (0.439 mole) of anhydrous magnesium chloride and 2.51 tetrahydrofuran (THF) are added to a 121 flask with a mechanical stirrer. 27.7 g (0.184 mole) of titanium tetrachloride were added dropwise to the mixture for 1/2 hour. It is necessary to heat at 60 ° C. for about 2/1 hour to completely dissolve this material.

500 g of porous chamber silica are added and the mixture is stirred for 4/1 hour. The mixture is dried for 3 to 5 hours at 60 ° C. under N ₂ discharge to give a dry and free flowable powder (same as the particle size of silica). The absorbed precursor composition has the following general formula.

TiMg 3.0 Cl ₁₀ (THF) 6.7

II. Activation process

The desired weight of immersed precursor composition and activator combinations are added to a tank containing an excess of anhydrous aliphatic hydrocarbon diluent such as isopentane to make a slurry system.

The activator compound and the precursor compound use an amount sufficient to obtain a partially activated precursor composition having an aluminum / titanium ratio of 0 to 10, preferably 4 to 8.

내지

시간 동안 완전히 혼합시키고 생성된 슬러리를 질소 또는 알곤같은 무수 불활성가스 도입하에 대기압 및 65±10°의 온도에서 탈수시켜 탄화수소 희석액을 건조시킨다. 얻어진 촉매는 부분적으로 활성화된 전구물질 조성물의 형태인데 실리카 구경내에 침지 시킨다. 이 물질은 실리카의 크기 및 형태를 갖는 유동성이 좋은 입상물질이다. 알루미늄 알킬함량이 10중량%의 하중을 초과하지 않는 한 비발화성이다. 사용하기전 질소 또는 알곤과 같은 무수불활성가스에 저장해준다. 이것은 완전한 활성화범위내에서 중합반응기로 주입될 수 있다.The mixture of the slurry system at room temperature and atmospheric pressure

To

The hydrocarbon dilution is dried by mixing thoroughly for hours and dehydrating the resulting slurry at atmospheric pressure and at a temperature of 65 ± 10 ° under the introduction of anhydrous inert gas such as nitrogen or argon. The catalyst obtained is in the form of a partially activated precursor composition which is immersed in silica aperture. This material is a fluid good particulate material having the size and shape of silica. As long as the aluminum alkyl content does not exceed a load of 10% by weight, it is non-flammable. Store in anhydrous inert gas such as nitrogen or argon before use. It can be injected into the polymerization reactor within the full range of activation.

An additional activator compound is fed to the polymerization reactor to complete activation of the precursor composition and to the reactor as a diluted solution dissolved in a hydrocarbon solvent such as isopentane. This dilution solution contains an activator compound in a volume ratio of 5 to 30%.

The activator compound is added to the polymerization reactor to maintain the ratio of aluminum / titanium in the reactor to about 10-400 and preferably 15-60.

The following examples illustrate the inventive process and are not limited in this range.

Example 1-6

인치이고 높이가

인 도면에 제시한 바와 같은 반응기가 사용되며 4 내지 6배의 Gmf의 가스속도 및 300psig의 압력하에서 진행된다. 내부 냉각기는 직경이 1인치이고 길이가 4f인 스텐레스강으로 된 4개의 수직루프로 이루어져 있는데 이곳을 예열수가 냉각액으로서 통과한다.In this example, the diameter (inside)

Inch and height

A reactor as shown in the figure is used and runs under a gas velocity of 4 to 6 times Gmf and a pressure of 300 psig. The internal cooler consists of four vertical loops of stainless steel, one inch in diameter and 4 f in length, through which preheated water passes as coolant.

The tube between the compressor and the reactor is jacketed to remove heat applied by the recycle compressor.

However, in Example 1, the internal cooler is located outside, and there is one tubular heat exchanger which is arranged such that the recycle gas flows through the tube to the preheated water.

Example 1

Ethylene and butene-1 or propylene are copolymerized for two years using a reactor equipped with an external heat exchanger as described above. For the first year, the reactor is closed for 15 hours and the next year for 17 hours to clean the external heat exchanger that forms the polymer from the resin particles. Catalyst A is used in the reactor through C as described above for two years of operation.

Example 2

As shown in FIG. 1, the reactor used in Example 1 was removed with an external heat exchanger and an internal heat exchanger was installed. The reactor uses an internal cooler while operating to copolymerize ethylene with butene-1 or propylene for 11 months without the need for closure. Through D, catalyst A is used in the reactor.

Example 3-6

These examples describe the specific operating conditions of the reactor described in Example 2, each using catalyst A through D.

Example 3

In the presence of the prepared catalyst A, it is reacted at an acceleration rate of 4 to 6 times Gmf with a pressure of 300 psig in the reactor described in Example 2. The catalyst contains 0.3 wt% Cr, 4.2 wt% Ti, 0.6 wt% F. Other reaction conditions and the properties of the resin produced are as follows.

Example 4

In the presence of the prepared catalyst B, ethylene and propylene are copolymerized at a gas velocity of 4-6 times Gmf and a pressure of 300 psig in a fluidized acid reactor consisting of the same diameter and internal cooler described in Example 2. The catalyst contains 1.7 weight percent Cr. Other reaction conditions and the properties of the resulting resin are as follows.

The reactor is operated in the presence of catalyst 3 for 26 hours under these conditions and there are no other problems.

Example 5

Ethylene and butene-1 are copolymerized in a fluidized bed reactor as described in Example 4 in the presence of prepared catalyst C at a gas velocity of 4-6 times Gmf and a pressure of 300 psig. The catalyst contains 0.3 wt% Cr and 0.9 wt% Al. Other reaction conditions and properties of the resulting resin are as follows.

The reactor is operated for 24 hours in the presence of catalyst C under these conditions and there are no other problems.

Example 6

Ethylene and butene-1 are copolymerized in a fluidized bed reactor as described in Example 4 in the presence of prepared catalyst D at a gas velocity of 4-6 Gmf and a pressure of 300 psig. The catalyst included 1.0 wt% Ti, 3.4 wt% Al, 3.4 wt Mg and 9 wt% THF. Other reaction conditions and properties of the resulting resin are as follows.

The reactor is operated for 16 hours in the presence of catalyst D under the above conditions and there are no other problems.

Claims (1)

In the preparation of solid granular polymer by continuous low pressure gas phase during exothermic polymerization in a vertical uniform diameter fluidized bed reactor, the gas phase and at least one polymerizable monomer having at least one polymerizable monomer are added to the fluidized bed of the polymer particles in the reactor. At a pressure of .00 psi, the exotherm of the reaction being removed by indirect cooling means in this reactor and withdrawing the particulate polymer from the reactor, and the amount of gas flowing through this fluidized bed in the minimum free traverse of the bed. A continuous low pressure gas phase process for producing a solid particulate polymer, characterized in that it is set to be in the range of about 1.5 to <10 Gmf based on area.

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