CN116082551A - Process for the batch production of polyethylene - Google Patents
Process for the batch production of polyethylene Download PDFInfo
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- CN116082551A CN116082551A CN202111305083.1A CN202111305083A CN116082551A CN 116082551 A CN116082551 A CN 116082551A CN 202111305083 A CN202111305083 A CN 202111305083A CN 116082551 A CN116082551 A CN 116082551A
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- -1 polyethylene Polymers 0.000 title claims abstract description 66
- 239000004698 Polyethylene Substances 0.000 title claims abstract description 61
- 229920000573 polyethylene Polymers 0.000 title claims abstract description 60
- 238000000034 method Methods 0.000 title claims abstract description 54
- 238000010923 batch production Methods 0.000 title claims description 8
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 163
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims abstract description 60
- 239000005977 Ethylene Substances 0.000 claims abstract description 60
- 239000004711 α-olefin Substances 0.000 claims abstract description 57
- 239000003054 catalyst Substances 0.000 claims abstract description 32
- 150000001335 aliphatic alkanes Chemical class 0.000 claims abstract description 30
- 229920006395 saturated elastomer Polymers 0.000 claims abstract description 25
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 15
- 238000005070 sampling Methods 0.000 claims abstract description 15
- 239000007789 gas Substances 0.000 claims description 81
- 238000011084 recovery Methods 0.000 claims description 44
- 239000000843 powder Substances 0.000 claims description 39
- 239000000463 material Substances 0.000 claims description 24
- 239000007791 liquid phase Substances 0.000 claims description 21
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 16
- 239000012071 phase Substances 0.000 claims description 16
- 239000001257 hydrogen Substances 0.000 claims description 15
- 229910052739 hydrogen Inorganic materials 0.000 claims description 15
- 238000004458 analytical method Methods 0.000 claims description 14
- 238000001704 evaporation Methods 0.000 claims description 12
- 230000008020 evaporation Effects 0.000 claims description 12
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 claims description 10
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims description 6
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 claims description 6
- 239000010936 titanium Substances 0.000 claims description 6
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 238000009834 vaporization Methods 0.000 claims description 5
- 230000008016 vaporization Effects 0.000 claims description 5
- JRZJOMJEPLMPRA-UHFFFAOYSA-N 1-nonene Chemical compound CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 claims description 4
- DCTOHCCUXLBQMS-UHFFFAOYSA-N 1-undecene Chemical compound CCCCCCCCCC=C DCTOHCCUXLBQMS-UHFFFAOYSA-N 0.000 claims description 4
- 239000011954 Ziegler–Natta catalyst Substances 0.000 claims description 4
- 150000001875 compounds Chemical class 0.000 claims description 4
- ZGEGCLOFRBLKSE-UHFFFAOYSA-N methylene hexane Natural products CCCCCC=C ZGEGCLOFRBLKSE-UHFFFAOYSA-N 0.000 claims description 4
- 239000011949 solid catalyst Substances 0.000 claims description 4
- CRSBERNSMYQZNG-UHFFFAOYSA-N 1 -dodecene Natural products CCCCCCCCCCC=C CRSBERNSMYQZNG-UHFFFAOYSA-N 0.000 claims description 2
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 claims description 2
- KWKAKUADMBZCLK-UHFFFAOYSA-N 1-octene Chemical compound CCCCCCC=C KWKAKUADMBZCLK-UHFFFAOYSA-N 0.000 claims description 2
- SNRUBQQJIBEYMU-UHFFFAOYSA-N Dodecane Natural products CCCCCCCCCCCC SNRUBQQJIBEYMU-UHFFFAOYSA-N 0.000 claims description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 2
- IAQRGUVFOMOMEM-UHFFFAOYSA-N butene Natural products CC=CC IAQRGUVFOMOMEM-UHFFFAOYSA-N 0.000 claims description 2
- 229940069096 dodecene Drugs 0.000 claims description 2
- 229910052736 halogen Inorganic materials 0.000 claims description 2
- 150000002367 halogens Chemical class 0.000 claims description 2
- 229910052749 magnesium Inorganic materials 0.000 claims description 2
- 239000011777 magnesium Substances 0.000 claims description 2
- AFFLGGQVNFXPEV-UHFFFAOYSA-N n-decene Natural products CCCCCCCCC=C AFFLGGQVNFXPEV-UHFFFAOYSA-N 0.000 claims description 2
- YWAKXRMUMFPDSH-UHFFFAOYSA-N pentene Chemical compound CCCC=C YWAKXRMUMFPDSH-UHFFFAOYSA-N 0.000 claims description 2
- 239000007921 spray Substances 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 24
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 abstract description 20
- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 abstract description 19
- 229920005989 resin Polymers 0.000 abstract description 8
- 239000011347 resin Substances 0.000 abstract description 8
- 229920013716 polyethylene resin Polymers 0.000 abstract description 6
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 38
- 239000001282 iso-butane Substances 0.000 description 19
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 17
- 238000003860 storage Methods 0.000 description 14
- 238000006243 chemical reaction Methods 0.000 description 12
- 238000010438 heat treatment Methods 0.000 description 12
- 238000007599 discharging Methods 0.000 description 11
- 239000000498 cooling water Substances 0.000 description 10
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 10
- 229910052757 nitrogen Inorganic materials 0.000 description 10
- VOITXYVAKOUIBA-UHFFFAOYSA-N triethylaluminium Chemical compound CC[Al](CC)CC VOITXYVAKOUIBA-UHFFFAOYSA-N 0.000 description 9
- 239000002904 solvent Substances 0.000 description 8
- 239000007788 liquid Substances 0.000 description 6
- 238000004587 chromatography analysis Methods 0.000 description 5
- 229920001903 high density polyethylene Polymers 0.000 description 5
- 239000004700 high-density polyethylene Substances 0.000 description 5
- 239000004743 Polypropylene Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229920001155 polypropylene Polymers 0.000 description 4
- 238000005119 centrifugation Methods 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- UAIZDWNSWGTKFZ-UHFFFAOYSA-L ethylaluminum(2+);dichloride Chemical compound CC[Al](Cl)Cl UAIZDWNSWGTKFZ-UHFFFAOYSA-L 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 239000004705 High-molecular-weight polyethylene Substances 0.000 description 1
- 229920010741 Ultra High Molecular Weight Polyethylene (UHMWPE) Polymers 0.000 description 1
- HQMRIBYCTLBDAK-UHFFFAOYSA-M bis(2-methylpropyl)alumanylium;chloride Chemical compound CC(C)C[Al](Cl)CC(C)C HQMRIBYCTLBDAK-UHFFFAOYSA-M 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000007334 copolymerization reaction Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- YNLAOSYQHBDIKW-UHFFFAOYSA-M diethylaluminium chloride Chemical compound CC[Al](Cl)CC YNLAOSYQHBDIKW-UHFFFAOYSA-M 0.000 description 1
- 239000002612 dispersion medium Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 230000037048 polymerization activity Effects 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 229930195734 saturated hydrocarbon Natural products 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- SQBBHCOIQXKPHL-UHFFFAOYSA-N tributylalumane Chemical compound CCCC[Al](CCCC)CCCC SQBBHCOIQXKPHL-UHFFFAOYSA-N 0.000 description 1
- MCULRUJILOGHCJ-UHFFFAOYSA-N triisobutylaluminium Chemical compound CC(C)C[Al](CC(C)C)CC(C)C MCULRUJILOGHCJ-UHFFFAOYSA-N 0.000 description 1
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 1
- LFXVBWRMVZPLFK-UHFFFAOYSA-N trioctylalumane Chemical compound CCCCCCCC[Al](CCCCCCCC)CCCCCCCC LFXVBWRMVZPLFK-UHFFFAOYSA-N 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
- C08F210/16—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
The invention relates to the field of resin, and discloses a method for intermittently preparing polyethylene, which can adjust the density of polyethylene resin and comprises the following steps: the method comprises the following steps: in the presence of a carbon tetra-saturated alkane and a catalyst, ethylene and alpha-olefin are contacted in a polymerization kettle to carry out polymerization reaction; in the polymerization reaction process, sampling and analyzing from a polymerization kettle at regular intervals to obtain the content ratio of ethylene to alpha-olefin in the polymerization kettle, and transmitting the content ratio to an alpha-olefin feeding system; the alpha-olefin feeding system adjusts the feeding amount of the alpha-olefin according to the content ratio, so that the content ratio of the ethylene to the alpha-olefin in the polymerization kettle is maintained within a preset range; wherein the alpha-olefin does not include ethylene. The method can effectively solve the problem that the density of the polyethylene resin is difficult to adjust in the intermittent production of the ultra-high molecular weight polyethylene device, and improves the utilization rate and economic benefit of the production device.
Description
Technical Field
The invention relates to the field of resins, in particular to a method for intermittently preparing polyethylene.
Background
Ultra High Molecular Weight Polyethylene (UHMWPE) is a polyethylene resin having a molecular weight in the range of 150 to 800 tens of thousands. UHMWPE has a larger molecular weight than ordinary polyethylene, so that the UHMWPE has excellent properties of impact resistance, wear resistance, self-lubrication, low temperature resistance, chemical corrosion resistance and the like, and is widely applied to the fields of coal mining industry, chemical industry, mechanical industry, textile industry, artificial prostheses, other fields and the like. The UHMW resin production process is similar to the production of common high density polyethylene HDPE, and can be produced by adopting the HDPE production technology, except that the UHMW-PE production process has no granulation process, and the product is in powder form. The preparation method of the ultra-high molecular weight polyethylene resin mainly adopts Ziegler catalyst, triethylaluminum as a cocatalyst, saturated hydrocarbon at 60-120 ℃ as a dispersion medium, and ethylene is polymerized under certain temperature and pressure conditions to prepare products with different molecular weights. However, in the production of polyethylene, the quality of the product is significantly reduced, whether the conventional low molecular weight polyethylene is blended with UHMWPE resin or UHMWPE resin is blended with conventional low molecular weight polyethylene. High quality UHMWPE resins are therefore commonly produced using batch processes.
In addition, the ultra-high molecular weight polyethylene has excellent product performance, and the characteristics of difficult processing limit the application of the ultra-high molecular weight polyethylene. This results in low user and low usage of ultra high molecular weight polyethylene. For enterprises producing ultra-high molecular weight polyethylene, it is often not possible to produce them at full capacity. These idle capacities also typically require the production of common polyethylene products. While conventional polyethylene products generally require adjustment of resin density for their use, devices for producing ultra-high molecular weight polyethylene generally do not have this capability.
In the process for producing polyethylene by a batch method in the prior art, due to large fluctuation of polymerization rate and polymerization activity in the production process, the method of directly injecting the comonomer into the reactor is difficult to be adopted according to the continuous polyethylene production process. There is therefore a need for a control method that can be used in batch polyethylene production to control the density of the polyethylene resin and expand the performance range of the polyethylene product.
Disclosure of Invention
The invention aims to solve the technical problems that the product of the ultra-high molecular weight polyethylene prepared by an intermittent method in the prior art is single, the variety is few, and the traditional slurry process uses traditional solvents such as hexane, solvent oil and the like, and needs the process steps of centrifugation, filtration, drying and the like.
The inventor of the invention finds in experiments that in the presence of the carbon tetra-saturated alkane and the catalyst, ethylene and alpha-olefin are contacted for polymerization reaction, the density of the produced polyethylene can be adjusted, and the density of a polyethylene product can be controlled on a batch process device for producing ultra-high molecular weight polyethylene, and the medium-high density polyethylene product is produced, so that the performance range of the polyethylene product is further enlarged. In addition, the method adopts the carbon tetra-saturated alkane as the suspension solvent to produce the ultra-high molecular weight polyethylene, compared with the traditional slurry process which uses traditional solvents such as hexane, solvent oil and the like, the method does not need the process steps such as centrifugation, filtration, drying and the like, does not need the equipment such as a centrifuge, a dryer and the like, and reduces the production cost.
In order to achieve the above object, the present invention provides in one aspect a process for preparing polyethylene batchwise, the process comprising:
in the presence of a carbon tetra-saturated alkane and a catalyst, ethylene and alpha-olefin are contacted in a polymerization kettle to carry out polymerization reaction;
in the polymerization reaction process, sampling and analyzing from a polymerization kettle at regular intervals to obtain the content ratio of ethylene to alpha-olefin in the polymerization kettle, and transmitting the content ratio to an alpha-olefin feeding system; the alpha-olefin feeding system adjusts the feeding amount of the alpha-olefin according to the content ratio, so that the content ratio of the ethylene to the alpha-olefin in the polymerization kettle is maintained within a preset range; wherein the alpha-olefin does not include ethylene.
The intermittent preparation method of polyethylene can effectively solve the problem that the intermittent production of ultra-high molecular weight polyethylene device is difficult to produce common polyethylene, can increase the variety of products of the intermittent production of ultra-high molecular weight polyethylene device, and effectively improves the utilization rate and economic benefit of the production device.
In addition, the polypropylene production equipment of the small-body polypropylene production factory is modified by adopting the invention, and the production of the ultra-high molecular weight polyethylene is very suitable for meeting the characteristic that downstream factories need small-batch goods. The ultra-high molecular weight polyethylene has higher price, and the technology can obviously improve the economic benefit of small-body polypropylene production factories.
Drawings
FIG. 1 is a schematic structural view of a system for batch production of polyethylene according to an embodiment of the present invention;
fig. 2 is a schematic structural view of a control system for batch production of polyethylene according to an embodiment of the present invention.
Description of the reference numerals
100 polymeric kettles, 200 recovery tanks, 300 gas storage equipment, 400 flash tanks, 500 vacuumizing equipment, 600 gas chromatography and 700 control equipment
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
In one aspect, the present invention provides a method for batch production of polyethylene, which can adjust the density of a polyethylene resin, the method comprising:
in the presence of a carbon tetra-saturated alkane and a catalyst, ethylene and alpha-olefin are contacted in a polymerization kettle to carry out polymerization reaction;
in the polymerization reaction process, sampling and analyzing from a polymerization kettle at regular intervals to obtain the content ratio of ethylene to alpha-olefin in the polymerization kettle, and transmitting the content ratio to an alpha-olefin feeding system; the alpha-olefin feeding system adjusts the feeding amount of the alpha-olefin according to the content ratio, so that the content ratio of the ethylene to the alpha-olefin in the polymerization kettle is maintained within a preset range; wherein the alpha-olefin does not include ethylene.
In some embodiments of the invention, the alpha-olefin is selected from at least one of butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, and isomers thereof, more preferably propylene and/or n-butene.
In some embodiments of the present invention, the feedstock of the tetrasaturated alkane contains an alpha olefin, wherein the content of alpha olefin in the feedstock of the tetrasaturated alkane is lower than the content of alpha olefin in the tetrasaturated alkane in the polymerization reaction. The carbon-tetra-saturated alkane may be a variety of carbon-tetra-saturated alkanes commonly known in the art, such as n-butane and/or isobutane.
In the invention, the density of polyethylene is reduced by adopting a mode of copolymerizing ethylene and alpha-olefin, the content ratio of ethylene and alpha-olefin is automatically controlled and stabilized by adopting feeding, and excessive soluble substances are prevented from being generated when the content of the alpha-olefin is too high, and kettle sticking occurs in the flash evaporation process. The polyethylene resin which can be produced is medium-high density polyethylene with the density ranging from 0.926 g/cm to 0.97g/cm 3 Preferably 0.93-0.97g/cm 3 Still more preferably 0.935 to 0.97g/cm 3 . The molar ratio of ethylene to alpha-olefin (e.g., 1:0.06-0.08) is determined according to the copolymerization capability of the catalyst, so that the density of the polyethylene product reaches the preset requirement. In the present invention, the content ratio of ethylene to alpha-olefin is referred to as molar ratioMolar ratio.
The amount of the carbon-tetrasaturated alkane used in the invention is determined according to the volume of the polymerization kettle, and the general feeding amount is 40-90% of the volume of the polymerization kettle. The ethylene and the alpha-olefin are continuously added along with the reaction, so that the yield of the polyethylene in the kettle can be measured according to the consumption of the ethylene and the alpha-olefin, and the volume concentration of the polyethylene in the tetra-saturated alkane during discharging is lower than 70 percent, preferably lower than 50 percent, and the discharging is difficult due to the excessive concentration. For safety reasons, the total volume of the carbon tetra-saturated alkane and the polyethylene in the reactor should not be less than 95%, preferably less than 90% of the volume of the ultra-high polymerization reactor during discharging. The catalyst dosage is determined according to the activity of the catalyst and the single kettle yield. The single pot polymerization time is generally from 0.5 to 12 hours depending on the active life of the catalyst.
In some embodiments of the invention, the contacting is performed in the presence of hydrogen in an amount such that the pressure within the system increases by 0.01 to 1.5MPa (this pressure refers to the partial pressure of hydrogen). The feeding order of the hydrogen gas is not limited in the present invention, and for example, the hydrogen gas may be fed into the polymerization vessel before the carbon-tetra-saturated alkane and the catalyst are fed into the polymerization vessel, or may be fed into the polymerization vessel after the carbon-tetra-saturated alkane and the catalyst are fed into the polymerization vessel and before the ethylene gas is introduced.
In some embodiments of the invention, the polymerization conditions include: the temperature is 50-100deg.C, preferably 60-90deg.C. The pressure is 2.3-3.8MPa, preferably 2.8-3.6MPa. In the present invention, the amount of ethylene to the carbon tetra-saturated alkane can be such that the pressure of the polymerization reaction system is controlled within the above range.
In some embodiments of the invention, the method further comprises:
(a) After the polymerization reaction is finished, the pressure of the polymerization kettle is reduced, unreacted ethylene, alpha-olefin and carbon tetra-saturated alkane are vaporized in the polymerization kettle, the obtained gas phase is condensed into a liquid phase material through a recovery condenser, and the liquid phase material enters a recovery tank.
In some embodiments of the invention, preferably, the vaporization temperature is 40-100 ℃, preferably 50-90 ℃.
In some embodiments of the invention, the method further comprises:
and (c) after the step (a) is finished, injecting materials in the kettle into a flash tank by utilizing residual pressure in the polymerization kettle to perform flash evaporation, and obtaining flash evaporation gas and polyethylene powder. Preferably, the pressure of the flash evaporation is 0-0.1MPa.
In some embodiments of the invention, the apparatus used for sampling analysis from the polymerizer is a gas chromatograph. The time between sampling analysis is less than 30 minutes, preferably less than 10 minutes, more preferably less than 5 minutes.
In the present invention, the catalyst is a polyethylene catalyst, and may be any catalyst capable of polymerizing ethylene into high molecular weight polyethylene, preferably a Ziegler-Natta catalyst.
According to the process of the present invention, the Ziegler-Natta catalyst comprises: (1) The active component of the titanium-containing solid catalyst comprises magnesium, titanium, halogen and an internal electron donor as main components; (2) an organoaluminum compound cocatalyst component; and (3) optionally an external electron donor component.
Solid catalysts available for use are commercially available from beijing aoda division, chinese petrochemical catalyst limited, such as: BCE catalyst, CM catalyst.
The organoaluminum compound as the cocatalyst component of the catalyst is preferably an alkylaluminum compound, more preferably at least one selected from trialkylaluminums (e.g., trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, trioctylaluminum, etc.), diethylaluminum chloride, diisobutylaluminum chloride, monoethylaluminum dichloride and ethylaluminum dichloride.
The ratio of the titanium-containing solid catalyst active component to the organoaluminum compound promoter component may be from 0.1:25 to 0.1:1000 in terms of Ti/Al molar ratio.
In the present invention, referring to fig. 1 and 2, the following are specific embodiments of the present invention:
1) Feeding a carbon-tetrasaturated alkane and a catalyst into a polymerization kettle 100;
2) Heating the polymerization kettle 100 to a preset polymerization temperature, and introducing ethylene gas and alpha-olefin into the polymerization kettle 100 to perform polymerization reaction; sampling and analyzing the gas chromatograph 600 from the reaction kettle at regular intervals in the reaction process to obtain the content ratio of ethylene to alpha-olefin in the polymerization kettle 100, and transmitting the content ratio to an alpha-olefin feeding system; the control apparatus 700 for alpha-olefin feeding adjusts the feeding amount of alpha-olefin according to the content ratio so that the content ratio of ethylene to alpha-olefin in the polymerizer 100 is maintained within a predetermined range, thereby producing a polyethylene product of a predetermined density;
3) After the polymerization reaction is finished, the pressure of the polymerization kettle is reduced, unreacted ethylene, alpha-olefin and carbon tetra-saturated alkane are vaporized in the polymerization kettle 100, the obtained gas phase is condensed into a liquid phase material through a recovery condenser, and the liquid phase material enters a recovery tank 200;
4) After recovery, the materials in the polymerization kettle are sprayed into the flash tank 400 by utilizing the residual pressure in the polymerization kettle to obtain flash gas and polyethylene powder, the flash gas is discharged, the gas is conveyed to the gas storage device 300, and the polyethylene powder is discharged from the bottom end of the polymerization kettle 100 to obtain the polyethylene.
In addition, optionally, hydrogen is fed into the polymerizer 100 in step 1) or into the polymerizer 100 before ethylene gas is fed in step 2). The amount of hydrogen is such that the pressure in the system increases by 0.01 to 1.5MPa (this pressure means hydrogen partial pressure). In step 2), the device for heating and removing heat of the polymerization kettle 100 is conventional equipment, and the typical heating equipment for heating the polymerization kettle 100 is to introduce hot water into a jacket of the polymerization kettle; the heat removal from the polymerizer 100 is achieved by feeding cold water into the polymerizer jacket. In step 3), the liquid phase material which is vaporized and condensed in the polymerization kettle 100 and enters the recovery tank 200 is mainly saturated alkane with carbon, contains a small amount of ethylene and alpha-olefin, and can be reused as a polymerization raw material.
In step 3 of the method of the present invention, the gas in the flash tank 400 is discharged into the gas storage device 300. The gas evacuated in the flash tank 400 and replaced with nitrogen also enters the gas storage device 300. The gas in the gas storage device 300 is recovered or harmlessly treated according to the production plant equipment.
More specifically, the process is carried out,
the feeding process of the step 1) is as follows, and the metered hydrogen is generally added into a polymerization kettle; the ziegler natta catalyst component is then added to the polymerizer 100 with a liquid carbon tetra-saturated alkane; and finally supplementing the carbon tetra-saturated alkane required by the process.
The specific process of the step 2) of the invention is as follows: heating the polymerization kettle 100, and adopting a hot water pump to send hot water to a jacket of the polymerization kettle 100 for heating, wherein the kettle temperature is increased from normal temperature to the polymerization temperature. The polymerization temperature is 50 to 100℃and preferably 60 to 90 ℃. At this time, ethylene gas and α -olefin were introduced into the polymerizer 100, and the polymerization was started. The pressure of the polymerization reaction is controlled by ethylene to be 2.3-3.8MPa, preferably 2.8-3.6MPa. The polymerization temperature rises to a preset polymerization rate, hot water (gradually closed under an automatic state) is switched into circulating cooling water (automatically adjusting the opening of a circulating cooling water valve), heat released by the polymerization reaction is removed, and the reaction temperature is controlled to be stable. Sampling and analyzing from the reaction kettle at regular intervals by using the gas chromatograph 600 to obtain the content ratio of ethylene to alpha-olefin in the polymerization kettle 100; the alpha-olefin feeding system adjusts the feeding amount of the alpha-olefin according to the content ratio, so that the content ratio of the ethylene to the alpha-olefin in the reaction kettle is maintained within a preset range.
The specific process of step 3) of the invention is that the polymerization reaction is finished (usually the polymerization time reaches the requirement, or the polyethylene yield reaches the requirement), unreacted ethylene and tetra-saturated alkane in the system are vaporized by reducing the pressure of the polymerization kettle 100, so as to realize the first step of separation and recovery, the vaporization speed is controlled in the vaporization process in the polymerization kettle 100, hot water is introduced into the jacket of the polymerization kettle, and the temperature of the polymerization kettle is controlled to be higher than 40 ℃, preferably higher than 45 ℃, and more preferably higher than 50 ℃; while the temperature of the polymerizer is brought to less than 100 c, preferably less than 90 c. The pressure of the polymerizer 100 is reduced by opening a valve connecting the polymerizer 100 to a recovery system (i.e., opening a recovery system) comprising the recovery condenser and the recovery tank 200. The recycling condenser can adopt circulating cooling water at 20-25 ℃ and control the pressure of the recycling tank to be 0.2-0.5MPa by discharging noncondensable gas. The discharged noncondensable gas is mainly ethylene and hydrogen, and can be recovered and used uniformly by factories. In general, the recovery tank 200 is left at room temperature, and the gas phase in the polymerization reactor 100 is continuously fed from the polymerization reactor 100 to the recovery tank 200 in the initial stage of recovery, and after the equilibrium is reached, the recovery is completed. At this time, a residual pressure is still present in the polymerization vessel 100, and preferably, the residual pressure in the polymerization vessel 100 is 0.2 to 0.5MPa.
The liquid phase material entering the recovery tank 200 after vaporization and condensation in the polymerization reactor 100 contains the tetra-saturated alkane, ethylene and α -olefin, and the liquid phase material can be reused as a raw material.
In the step 4), flash gas is discharged so as to reduce the adsorption quantity of combustible gas in the polyethylene powder, and the separation and recovery in the second step are realized. The specific method for discharging the flash gas comprises the following steps: firstly, the pressure is relieved to the gas storage device 300: opening a valve between the flash tank 400 and the gas storage device 300 to discharge the gas in the flash tank 400 into the gas storage device 300, and reducing the pressure of the flash tank 400 to the pressure of the gas storage device 300; then, the vacuumizing device 500 is used for vacuumizing to further reduce the combustible gas in the polyethylene powder, and the pumped gas also enters the gas storage device 300. The gas in the gas storage device 300 is recovered according to the small-body polypropylene production plant. The time of the evacuation is based on the qualification of the combustible gas content in the flash tank 400. After the combustible gas content in the flash tank 400 is qualified, nitrogen is filled into the flash tank 400, and polyethylene powder is discharged out of the flash tank 400 and enters a powder bin or is packaged. And then, testing the melt index, the melt mass flow rate and the like of the powder product, and grading the product according to the testing result.
In the present invention, the pressures refer to gauge pressure.
The present invention will be described in detail by examples.
The experimental results in the examples were obtained according to the following test methods, in which the operations were performed under room temperature environments without particular limitation:
the main catalyst is BCE catalyst, which is obtained from Beijing Orda division of China petrochemical catalyst Co.
The promoter component is triethylaluminum, and the catalyst component is prepared into 0.35mol/L by dehydrated hexane for use.
Isobutane contains a small amount of other saturated alkanes with a purity of more than 99mol%.
Melt index (MFR): measured according to GB/T3682.1-2018 at 190℃under a load of 2.16 kg.
Density: measured according to the method described in GB/T1033.2-2010.
The volume of the polymerizer was 5L, and a jacket (not shown) was provided outside. The recycling condenser adopts circulating cooling water at 20-25 ℃.
Example 1
A polymerization kettle was charged with 15.1mg of BCE catalyst and 10mL of triethylaluminum solution using 2 liters of liquid isobutane. Heating the reaction kettle by jacket hot water of the polymerization kettle, when the temperature of the polymerization kettle reaches 60 ℃, the gauge pressure of the polymerization kettle rises to 0.87MPa, adding hydrogen into the polymerization kettle to raise the kettle pressure to 2.07MPa, adding ethylene to raise the polymerization kettle pressure to 3.27MPa, adding propylene, and controlling the molar ratio of the gas phase propylene to the ethylene to be 0.06 according to the analysis value of the gas phase chromatography (sampling analysis every 3 min). The flow rate of the cooling water was adjusted according to the polymerization pot temperature, thereby maintaining the polymerization temperature. After the polymerization reaction is carried out for 60 minutes, a valve connecting the polymerization kettle and a recovery system is opened, the pressure of the polymerization kettle is released, unreacted ethylene and isobutane are vaporized in the polymerization kettle, the obtained gas phase is condensed into a liquid phase material through a recovery condenser, and the liquid phase material enters a recovery tank. Controlling the pressure release speed, and introducing hot water into the jacket of the polymerization kettle to ensure that the temperature in the kettle is 50 ℃, and stopping recovery when the kettle pressure is reduced to 0.32 MPa. Discharging the gas in the kettle and the polyethylene powder into a flash tank for flash evaporation (gauge pressure is 0.01 MPa), and opening a valve between the flash tank and a gas holder to discharge the gas in the flash tank into the gas holder; and the pressure of the flash tank is reduced to normal pressure, a vacuum pump is started to vacuumize the flash tank to minus 0.08MPa for 60 minutes, and isobutane adsorbed by the polyethylene powder in the flash tank is removed. Then, nitrogen was charged into the flash tank to normal pressure, and the powder in the tank was discharged and weighed to obtain 242g of polyethylene powder. The powder was tested and the results are shown in Table 1.
Example 2
21.4mg of BCE catalyst and 10mL of triethylaluminum solution were charged to the polymerization vessel with 2 liters of a mixture of liquid isobutane at 20 ℃. Heating the reaction kettle by jacket hot water of the polymerization kettle, when the temperature of the polymerization kettle reaches 70 ℃, the gauge pressure of the polymerization kettle is raised to 1.1MPa, adding hydrogen into the polymerization kettle to raise the kettle pressure to 2.3MPa, adding ethylene to raise the polymerization kettle pressure to 3MPa, adding propylene, and controlling the molar ratio of gas phase propylene to ethylene to be 0.07 according to the analysis value of chromatography (sampling analysis every 3 min). The flow rate of the cooling water was adjusted according to the polymerization pot temperature, thereby maintaining the polymerization temperature. After the polymerization reaction is carried out for 60 minutes, a valve connecting the polymerization kettle and a recovery system is opened, the pressure of the polymerization kettle is released, unreacted ethylene and isobutane are vaporized in the polymerization kettle, the obtained gas phase is condensed into a liquid phase material through a recovery condenser, and the liquid phase material enters a recovery tank. Controlling the pressure release speed, and introducing hot water into the jacket of the polymerization kettle to ensure that the temperature in the kettle is 55 ℃, and stopping recovery when the kettle pressure is reduced to 0.32 MPa. Discharging the gas in the kettle and the polyethylene powder into a flash tank for flash evaporation (gauge pressure is 0.01 MPa), and opening a valve between the flash tank and a gas holder to discharge the gas in the flash tank into the gas holder; and the pressure of the flash tank is reduced to normal pressure, a vacuum pump is started to vacuumize the flash tank to minus 0.08MPa for 60 minutes, and isobutane adsorbed by the polyethylene powder in the flash tank is removed. Then, nitrogen is filled into the flash tank to normal pressure, and the powder in the tank is discharged and weighed, so as to obtain 293g of polyethylene powder. The powder was tested and the results are shown in Table 1.
Example 3
23.1mg of BCE catalyst and 10mL of triethylaluminum solution were charged into the polymerization vessel with 2 liters of a mixture of liquid isobutane at 20 ℃. Heating the reaction kettle by jacket hot water of the polymerization kettle, when the temperature of the polymerization kettle reaches 70 ℃, the gauge pressure of the polymerization kettle rises to 1.1MPa, adding hydrogen into the polymerization kettle to raise the kettle pressure to 2.3MPa, adding ethylene to raise the polymerization kettle pressure to 3MPa, adding n-butene, and controlling the molar ratio of gas phase n-butene to ethylene to be 0.07 according to the analysis value of chromatography (sampling analysis every 3 min). The flow rate of the cooling water was adjusted according to the polymerization pot temperature, thereby maintaining the polymerization temperature. After the polymerization reaction is carried out for 60 minutes, a valve connecting the polymerization kettle and a recovery system is opened, the pressure of the polymerization kettle is released, unreacted ethylene and isobutane are vaporized in the polymerization kettle, the obtained gas phase is condensed into a liquid phase material through a recovery condenser, and the liquid phase material enters a recovery tank. Controlling the pressure release speed, and introducing hot water into the jacket of the polymerization kettle to ensure that the temperature in the kettle is 55 ℃, and stopping recovery when the kettle pressure is reduced to 0.32 MPa. Discharging the gas in the kettle and the polyethylene powder into a flash tank for flash evaporation (gauge pressure is 0.01 MPa), and opening a valve between the flash tank and a gas holder to discharge the gas in the flash tank into the gas holder; and the pressure of the flash tank is reduced to normal pressure, a vacuum pump is started to vacuumize the flash tank to minus 0.08MPa for 60 minutes, and isobutane adsorbed by the polyethylene powder in the flash tank is removed. Then, nitrogen was charged into the flash tank to normal pressure, and the powder in the tank was discharged and weighed to obtain 317g of polyethylene powder. The powder was tested and the results are shown in Table 1.
Example 4
18.6mg of BCE catalyst and 10mL of triethylaluminum solution were charged to the polymerization vessel with 2 liters of a liquid isobutane mixture at 20 ℃. Heating the reaction kettle by jacket hot water of the polymerization kettle, when the temperature of the polymerization kettle reaches 70 ℃, the gauge pressure of the polymerization kettle rises to 1.5MPa, adding hydrogen into the polymerization kettle to raise the kettle pressure to 2.3MPa, adding ethylene to raise the polymerization kettle pressure to 3MPa, adding n-butene, and controlling the molar ratio of gas phase n-butene to ethylene to be 0.07 according to the analysis value of chromatography (sampling analysis every 3 min). The flow rate of the cooling water was adjusted according to the polymerization pot temperature, thereby maintaining the polymerization temperature. After the polymerization reaction is carried out for 60 minutes, a valve connecting the polymerization kettle and a recovery system is opened, the pressure of the polymerization kettle is released, unreacted ethylene and isobutane are vaporized in the polymerization kettle, the obtained gas phase is condensed into a liquid phase material through a recovery condenser, and the liquid phase material enters a recovery tank. Controlling the pressure release speed, and introducing hot water into the jacket of the polymerization kettle to ensure that the temperature in the kettle is 55 ℃, and stopping recovery when the kettle pressure is reduced to 0.32 MPa. Discharging the gas in the kettle and the polyethylene powder into a flash tank for flash evaporation (gauge pressure is 0.01 MPa), and opening a valve between the flash tank and a gas holder to discharge the gas in the flash tank into the gas holder; and the pressure of the flash tank is reduced to normal pressure, a vacuum pump is started to vacuumize the flash tank to minus 0.08MPa for 60 minutes, and isobutane adsorbed by the polyethylene powder in the flash tank is removed. Then, nitrogen was charged into the flash tank to normal pressure, and the powder in the tank was discharged and weighed to obtain 277g of polyethylene powder. The powder was tested and the results are shown in Table 1.
Example 5
17.4mg of BCE catalyst and 10mL of triethylaluminum solution were charged to the polymerization vessel with 2 liters of a liquid isobutane mixture at 20 ℃. Heating the reaction kettle by jacket hot water of the polymerization kettle, when the temperature of the polymerization kettle reaches 80 ℃, the gauge pressure of the polymerization kettle rises to 1.7MPa, adding hydrogen into the polymerization kettle to raise the kettle pressure to 1.9MPa, adding ethylene to raise the polymerization kettle pressure to 3MPa, adding n-butene, and controlling the molar ratio of gas phase n-butene to ethylene to be 0.07 according to the analysis value of chromatography (sampling analysis every 3 min). The flow rate of the cooling water was adjusted according to the polymerization pot temperature, thereby maintaining the polymerization temperature. After the polymerization reaction is carried out for 60 minutes, a valve connecting the polymerization kettle and a recovery system is opened, the pressure of the polymerization kettle is released, unreacted ethylene and isobutane are vaporized in the polymerization kettle, the obtained gas phase is condensed into a liquid phase material through a recovery condenser, and the liquid phase material enters a recovery tank. Controlling the pressure release speed, and introducing hot water into the jacket of the polymerization kettle to ensure that the temperature in the kettle is 55 ℃, and stopping recovery when the kettle pressure is reduced to 0.32 MPa. Discharging the gas in the kettle and the polyethylene powder into a flash tank for flash evaporation (gauge pressure is 0.01 MPa), and opening a valve between the flash tank and a gas holder to discharge the gas in the flash tank into the gas holder; and the pressure of the flash tank is reduced to normal pressure, a vacuum pump is started to vacuumize the flash tank to minus 0.08MPa for 60 minutes, and isobutane adsorbed by the polyethylene powder in the flash tank is removed. Then, nitrogen was charged into the flash tank to normal pressure, and the powder in the tank was discharged and weighed to obtain 283g of polyethylene powder. The powder was tested and the results are shown in Table 1.
Comparative example 1
Hydrogen was added to the polymerization vessel to raise the vessel pressure by 0.6MPa, and 25.7mg of BCE catalyst and 10.0mL of triethylaluminum solution were charged into the polymerization vessel with 2 liters of isobutane. Heating the reaction kettle by jacket hot water of the polymerization kettle, when the temperature of the polymerization kettle reaches 65 ℃, rising the gauge pressure of the polymerization kettle to 3.0MPa, adding ethylene to raise the pressure of the polymerization kettle to 3.3MPa, and starting to perform polymerization reaction; the flow rate of the cooling water was adjusted according to the polymerization pot temperature, thereby maintaining the polymerization temperature. After the polymerization reaction is carried out for 150 minutes, a valve connecting the polymerization kettle and a recovery system is opened, the pressure of the polymerization kettle is released, unreacted ethylene and isobutane are vaporized in the polymerization kettle, the obtained gas phase is condensed into a liquid phase material through a recovery condenser, and the liquid phase material enters a recovery tank; when the autoclave pressure was reduced to 1.5MPa, recovery was stopped. Discharging the gas in the kettle and the polyethylene powder into a flash tank (gauge pressure is 0.01 MPa), and opening a valve between the flash tank and the gas storage equipment to discharge the gas in the flash tank into the gas storage equipment; the pressure of the flash tank is reduced to normal pressure, then nitrogen is filled to 0.4MPa, and the gas after nitrogen replacement is also discharged into gas storage equipment, so that after 3 times of nitrogen replacement, the powder in the tank is discharged and weighed, and 285g of polyethylene powder is obtained. The powder was tested and the results are shown in Table 1.
TABLE 1
As can be seen from the results in Table 1, the polyethylene density in examples 1-5 can be obtained by adopting the technical scheme of the present application, which shows that the polyethylene density has a remarkable effect by adopting the method of the present invention, thereby effectively improving the utilization rate and economic benefit of the production device.
In addition, the invention adopts the carbon tetra-saturated alkane as the suspending solvent to produce the polyethylene, compared with the traditional slurry process which uses the traditional solvents such as hexane, solvent oil and the like, the invention does not need the process steps such as centrifugation, filtration, drying and the like, does not need the equipment such as a centrifuge, a dryer and the like, and reduces the production cost.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (10)
1. A process for the batch production of polyethylene, the process comprising:
in the presence of a carbon tetra-saturated alkane and a catalyst, ethylene and alpha-olefin are contacted in a polymerization kettle to carry out polymerization reaction;
in the polymerization reaction process, sampling and analyzing from a polymerization kettle at regular intervals to obtain the content ratio of ethylene to alpha-olefin in the polymerization kettle, and transmitting the content ratio to an alpha-olefin feeding system; the alpha-olefin feeding system adjusts the feeding amount of the alpha-olefin according to the content ratio, so that the content ratio of the ethylene to the alpha-olefin in the polymerization kettle is maintained within a preset range; wherein the alpha-olefin does not include ethylene.
2. The process according to claim 1, wherein the alpha-olefin is selected from at least one of butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene and isomers thereof, more preferably propylene and/or n-butene.
3. The process according to claim 1 or 2, wherein the contacting is performed in the presence of hydrogen in an amount such that the pressure within the system increases by 0.01-1.5MPa;
and/or, the hydrogen is fed into the polymerizer before feeding the tetra-saturated alkane and the catalyst into the polymerizer, or is fed into the polymerizer after feeding the tetra-saturated alkane and the catalyst into the polymerizer and before feeding the ethylene gas.
4. The method of claim 1 or 2, wherein the polymerization conditions include: the temperature is 50-100deg.C, preferably 60-90deg.C; the pressure is 2.3-3.8MPa, preferably 2.8-3.6MPa.
5. The method of claim 1, wherein the method further comprises:
(a) After the polymerization reaction is finished, the pressure of the polymerization kettle is reduced, unreacted ethylene, alpha-olefin and carbon tetra-saturated alkane are vaporized in the polymerization kettle, the obtained gas phase is condensed into a liquid phase material through a recovery condenser, and the liquid phase material enters a recovery tank.
6. The method according to claim 5, wherein the vaporization temperature is 40-100 ℃, preferably 50-90 ℃.
7. The method according to claim 5 or 6, wherein the method further comprises:
after the step (a) is finished, utilizing residual pressure in the polymerization kettle to spray materials in the kettle into a flash tank for flash evaporation, so as to obtain flash evaporation gas and polyethylene powder;
preferably, the conditions of the flash evaporation include: the pressure is 0-0.1MPa.
8. The method according to any one of claims 1 to 7, wherein the apparatus for sampling analysis from the polymerizer is a gas chromatograph.
9. A method according to claim 1 or 8, wherein the time between sampling analysis intervals is less than 30 minutes, preferably less than 10 minutes.
10. The process according to any one of claims 1-9, wherein the catalyst is a Ziegler-Natta catalyst comprising: (1) A titanium-containing solid catalyst active component containing magnesium, titanium, halogen and an internal electron donor; (2) an organoaluminum compound cocatalyst component; and (3) optionally an external electron donor component.
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