CN114621369A - Ethylene gas-phase polymerization grade switching agent and preparation method thereof - Google Patents
Ethylene gas-phase polymerization grade switching agent and preparation method thereof Download PDFInfo
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- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 title claims abstract description 131
- 239000005977 Ethylene Substances 0.000 title claims abstract description 131
- 239000003795 chemical substances by application Substances 0.000 title claims abstract description 120
- 238000012685 gas phase polymerization Methods 0.000 title claims abstract description 119
- 238000002360 preparation method Methods 0.000 title abstract description 20
- 239000003054 catalyst Substances 0.000 claims abstract description 308
- 238000000034 method Methods 0.000 claims abstract description 180
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 107
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 107
- 239000010936 titanium Substances 0.000 claims abstract description 107
- -1 polyethylene Polymers 0.000 claims abstract description 100
- 239000004698 Polyethylene Substances 0.000 claims abstract description 87
- 229920000573 polyethylene Polymers 0.000 claims abstract description 87
- 229940063655 aluminum stearate Drugs 0.000 claims abstract description 69
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 59
- 239000011651 chromium Substances 0.000 claims abstract description 59
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 59
- CEGOLXSVJUTHNZ-UHFFFAOYSA-K aluminium tristearate Chemical compound [Al+3].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O CEGOLXSVJUTHNZ-UHFFFAOYSA-K 0.000 claims abstract description 54
- 239000002270 dispersing agent Substances 0.000 claims abstract description 49
- LDDQLRUQCUTJBB-UHFFFAOYSA-N ammonium fluoride Chemical compound [NH4+].[F-] LDDQLRUQCUTJBB-UHFFFAOYSA-N 0.000 claims abstract description 34
- 229910052809 inorganic oxide Inorganic materials 0.000 claims abstract description 17
- 239000002994 raw material Substances 0.000 claims abstract description 17
- 238000004519 manufacturing process Methods 0.000 claims abstract description 14
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 155
- 239000007789 gas Substances 0.000 claims description 95
- 229910052757 nitrogen Inorganic materials 0.000 claims description 77
- 238000001994 activation Methods 0.000 claims description 53
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 42
- 239000000203 mixture Substances 0.000 claims description 35
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 34
- 239000007787 solid Substances 0.000 claims description 32
- 238000003756 stirring Methods 0.000 claims description 32
- 238000002156 mixing Methods 0.000 claims description 28
- 230000004913 activation Effects 0.000 claims description 26
- 239000012452 mother liquor Substances 0.000 claims description 22
- 150000004945 aromatic hydrocarbons Chemical class 0.000 claims description 19
- 238000001035 drying Methods 0.000 claims description 19
- 239000011261 inert gas Substances 0.000 claims description 18
- 239000000377 silicon dioxide Substances 0.000 claims description 17
- 238000001914 filtration Methods 0.000 claims description 16
- 238000001816 cooling Methods 0.000 claims description 15
- 239000002245 particle Substances 0.000 claims description 15
- 239000011148 porous material Substances 0.000 claims description 15
- 238000004537 pulping Methods 0.000 claims description 15
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 12
- 150000001335 aliphatic alkanes Chemical class 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 8
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 6
- 238000006116 polymerization reaction Methods 0.000 claims description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 4
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 claims description 4
- OFBQJSOFQDEBGM-UHFFFAOYSA-N Pentane Chemical group CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 claims description 4
- 230000003213 activating effect Effects 0.000 claims description 4
- 238000007598 dipping method Methods 0.000 claims description 4
- 150000003839 salts Chemical class 0.000 claims description 4
- FPGGTKZVZWFYPV-UHFFFAOYSA-M tetrabutylammonium fluoride Chemical compound [F-].CCCC[N+](CCCC)(CCCC)CCCC FPGGTKZVZWFYPV-UHFFFAOYSA-M 0.000 claims description 4
- MIMUSZHMZBJBPO-UHFFFAOYSA-N 6-methoxy-8-nitroquinoline Chemical class N1=CC=CC2=CC(OC)=CC([N+]([O-])=O)=C21 MIMUSZHMZBJBPO-UHFFFAOYSA-N 0.000 claims description 3
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims description 2
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 claims description 2
- 239000002904 solvent Substances 0.000 claims description 2
- 239000008096 xylene Substances 0.000 claims description 2
- 230000008569 process Effects 0.000 abstract description 139
- 230000007704 transition Effects 0.000 abstract description 6
- 239000012071 phase Substances 0.000 description 136
- 238000006243 chemical reaction Methods 0.000 description 118
- 239000000243 solution Substances 0.000 description 47
- 239000000463 material Substances 0.000 description 43
- 239000001257 hydrogen Substances 0.000 description 29
- 229910052739 hydrogen Inorganic materials 0.000 description 29
- 238000007599 discharging Methods 0.000 description 26
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 16
- 150000002431 hydrogen Chemical class 0.000 description 13
- 238000005303 weighing Methods 0.000 description 13
- 230000009471 action Effects 0.000 description 12
- 238000009826 distribution Methods 0.000 description 12
- 239000008187 granular material Substances 0.000 description 12
- 239000012968 metallocene catalyst Substances 0.000 description 12
- 238000012545 processing Methods 0.000 description 12
- 239000011347 resin Substances 0.000 description 12
- 229920005989 resin Polymers 0.000 description 12
- 238000002791 soaking Methods 0.000 description 12
- 238000003860 storage Methods 0.000 description 12
- VOITXYVAKOUIBA-UHFFFAOYSA-N triethylaluminium Chemical compound CC[Al](CC)CC VOITXYVAKOUIBA-UHFFFAOYSA-N 0.000 description 11
- 239000010413 mother solution Substances 0.000 description 10
- 238000010586 diagram Methods 0.000 description 8
- LXPCOISGJFXEJE-UHFFFAOYSA-N oxifentorex Chemical compound C=1C=CC=CC=1C[N+](C)([O-])C(C)CC1=CC=CC=C1 LXPCOISGJFXEJE-UHFFFAOYSA-N 0.000 description 8
- 229920001903 high density polyethylene Polymers 0.000 description 7
- 239000004700 high-density polyethylene Substances 0.000 description 7
- 239000002574 poison Substances 0.000 description 5
- 231100000614 poison Toxicity 0.000 description 5
- 239000011954 Ziegler–Natta catalyst Substances 0.000 description 4
- PAFZNILMFXTMIY-UHFFFAOYSA-N cyclohexylamine Chemical compound NC1CCCCC1 PAFZNILMFXTMIY-UHFFFAOYSA-N 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 229920000092 linear low density polyethylene Polymers 0.000 description 3
- 239000004707 linear low-density polyethylene Substances 0.000 description 3
- 235000012239 silicon dioxide Nutrition 0.000 description 3
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 description 2
- 229920001684 low density polyethylene Polymers 0.000 description 2
- 239000004702 low-density polyethylene Substances 0.000 description 2
- 150000002902 organometallic compounds Chemical class 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 208000005156 Dehydration Diseases 0.000 description 1
- 229920010126 Linear Low Density Polyethylene (LLDPE) Polymers 0.000 description 1
- 208000010378 Pulmonary Embolism Diseases 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000011549 displacement method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
- DZLFLBLQUQXARW-UHFFFAOYSA-N tetrabutylammonium Chemical compound CCCC[N+](CCCC)(CCCC)CCCC DZLFLBLQUQXARW-UHFFFAOYSA-N 0.000 description 1
- LALRXNPLTWZJIJ-UHFFFAOYSA-N triethylborane Chemical compound CCB(CC)CC LALRXNPLTWZJIJ-UHFFFAOYSA-N 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
- 238000013022 venting Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- 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
- C08F10/00—Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
- C08F10/02—Ethene
-
- 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
- C08F210/02—Ethene
-
- 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
Abstract
The invention relates to an ethylene gas phase polymerization grade switching agent, which is used for on-line switching of a titanium catalyst into a chromium catalyst in a gas phase polyethylene device, wherein the raw material of the ethylene gas phase polymerization grade switching agent comprises ammonium fluoride salt, aluminum stearate and an inorganic oxide dispersing agent, wherein the total content of the ammonium fluoride salt and the aluminum stearate is 0.1-10.0 wt%, the molar ratio of the ammonium fluoride salt to the aluminum stearate is 1-5: 1, and the content of the inorganic oxide dispersing agent is 90.0-99.9 wt%. The invention also relates to a preparation method of the ethylene gas-phase polymerization grade switching agent. The polyethylene gas-phase polymerization grade switching agent can enable a gas-phase polyethylene device to switch a titanium system into a chromium system catalyst on line for production, catalyst feeding equipment does not need to be newly added in the whole catalyst switching process, the device does not need to be stopped and a seed bed does not need to be replaced, and the polyethylene gas-phase polymerization grade switching agent is simple in operation, easy to implement and short in transition time.
Description
Technical Field
The invention relates to a fluidized bed polyethylene process, in particular to an ethylene gas phase polymerization grade switching agent.
Background
Polyethylene (PE) mainly includes Low Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), High Density Polyethylene (HDPE) and some products with special properties. As the LLDPE has a molecular structure similar to that of HDPE and is linear and has the same place in the production process as a part of HDPE, a plurality of newly designed devices can produce 0.910-0.970 g/cm by changing the feed composition and process parameters3The full density polyethylene (LLDPE/HDPE switching units for short). Most of the devices for producing LLDPE have great flexibility and market strain capacity, and the devices for producing HDPE have great flexibility and market strain capacity, so that the devices for producing the HDPE develop rapidly and become a development trend of PE production devices. With the construction and the production of multiple PE new or expanded devices, the production capacity of PE in China is continuously increased.
At present, the more advanced and mature full-density gas phase process in the world mainly comprises a Uniopl process of a Unition company, an Innovene process of an Inoes company, a Spherilene process of a Basell company, an Evolue process of a Mitsui chemical company and a North Star (Bastar) process of a northern Europe chemical company, wherein the Unipol process adopting the U.S. UCC accounts for about 50 percent. The catalyst is the core of olefin polymerization process, and the catalyst systems commonly used in gas-phase polyethylene process include three major types of Z-N, chromium and metallocene catalysts. The products produced by the three catalysts have various characteristics. Production plants typically choose which catalytic system to use for polyethylene production scheduling depending on the needs of the downstream market. This requires the apparatus to switch between catalysts. The three catalyst systems are mutually incompatible and have large differences in activity and process control parameters. Generally, a titanium catalyst or a metallocene catalyst in a gas-phase polyethylene process is a poison of a chromium catalyst, a shutdown and a bed change are needed for producing the chromium catalyst after producing the titanium catalyst or the metallocene catalyst, the titanium catalyst or the metallocene catalyst in a bed layer is thoroughly cleaned, and the time of the whole process is long.
The Zhouyi introduces in the sixth youth academic society of the petroleum institute of China, how to realize continuous and stable switching of titanium products and chromium products under two different catalyst systems after the popularization of the Dushan petrochemical company in 2002, and particularly performs detailed analysis and empirical summary on the product performance, the process transformation process and the process parameter control key points in the process of transformation of the high-density HD5410 brand and the chromium brand HD4801 produced by titanium catalysts. However, the specific switching process and operation steps of the titanium-based and chromium-based catalysts are not disclosed.
CN201510774219.1 discloses an on-line catalyst switching method for a gas-phase fluidized bed, which comprises the following steps: closing hydrogen feeding in advance, consuming hydrogen in the reaction system, stopping adding the catalyst during switching, returning the first catalyst in the catalyst feeder, and thoroughly purging the whole catalyst feeding and conveying system by refined nitrogen to convey the second catalyst. Maintaining the reactor process conditions consumes the first catalyst in the bed at a lower load. Nitrogen was used to displace the hydrogen in the reactor to below 250ppm when venting occurred to the reactor. The metallocene catalyst is added in small amounts to the reactor to maintain the reaction at a lower load, displacing the bed. The technology realizes the switching between different systems of catalysts without stopping the bed for changing. However, the technology needs to close the hydrogen feeding 2-5 days in advance, so that a large amount of transition materials are generated, and the profit and the benefit of a production device are influenced.
CN201580075805.5 discloses a method for switching between two incompatible catalyst systems, Z-N catalyst system and metallocene catalyst, said method comprising: (a) stopping the introduction of the first catalyst from the first catalyst feed system into the reactor; (b) introducing a catalyst deactivator to at least partially deactivate the first catalyst within the reactor; (c) introducing a second catalyst into the reactor from a second catalyst feed system separate from the first catalyst feed system. The technology can realize the back-and-forth switching of the Z-N catalyst system and the metallocene catalyst on the polyethylene device, but the switching process can be realized only by using two sets of independent catalyst feeding systems. Existing plants rarely design spare independent catalyst feed systems due to patent licensing and cost savings. In addition, in the device designed with two sets of independent catalyst collecting systems, if the catalyst feeding system cannot be timely and cleanly treated in the switching process, the catalyst system running before is easy to cause the blockage of the feeding system, and the parking risk of the device is increased.
CN201680082258.8 discloses a process for transitioning from a first continuous polymerization conducted in a gas phase reactor in the presence of a metallocene catalyst to a second polymerization conducted in the gas phase reactor in the presence of a ziegler-natta catalyst, wherein the metallocene catalyst and the ziegler-natta catalyst are incompatible, said process comprising: (a) discontinuing the introduction of the metallocene catalyst into the gas phase reactor; (b) introducing an effective amount of cyclohexylamine into the reactor to at least partially deactivate the metallocene catalyst; (c) introducing an organometallic compound into the reactor and reacting the organometallic compound with cyclohexylamine; (d) degassing the gas composition of the reactor and establishing a new composition within the reactor for the second polymerization using a ziegler-natta catalyst; (e) introducing the Ziegler-Natta catalyst into the reactor. This technique also requires the use of two separate catalyst addition systems during the switchover process.
CN201210402797.9 discloses a switching process of a titanium catalyst and a chromium catalyst of polyethylene by a vapor phase method. The process firstly utilizes a terminator CO2Terminating the reaction of the polyethylene titanium catalyst, then performing nitrogen replacement, and when the nitrogen replacement is finished, injecting a titanium catalyst and an eliminating agent H of a cocatalyst of the titanium catalyst into the reactor2And (3) reacting O, finally, after adjusting the components of the reactor, adding a chromium catalyst to establish a reaction, wherein a seedbed is not required to be replaced in the whole catalyst switching process. However, this process requires the injection of CO into the reactor during the switching process2And small molecular polar substances such as water, which are poisons for the catalyst. The chromium-containing catalyst is firstly adsorbed on a seed bed of the reactor after being injected into the reactor, and N is needed before the chromium-containing catalyst is injected into the reactor again to establish reaction2The pressure displacement method removes these polar substances. In the process, the original raw materials such as ethylene and the like in the reactor need to be emptied, and a large amount of nitrogen is also needed for replacement, so that the raw materials are wasted, and the cost is increased; the material level in the reactor is maintained at a low level to avoid the formation of sheeting in the reactor or the entrainment of fines into the recycle line which can lead to the production plant being forced to shut down.
There is therefore a great need for a switching technique between fast gas phase polyethylene incompatible catalyst systems such as titanium and chromium based catalysts, metallocene catalysts and chromium based catalysts that does not require the replacement of the seedbed nor the injection of catalyst poisons into the reactor. The ethylene gas phase polymerization grade switching agent and the switching method provided by the invention do not need to be additionally provided with equipment, the whole catalyst switching process does not need to be stopped or catalyst poison is not injected into a reactor, the seed bed replacement and nitrogen pressure replacement are avoided, the material loss and equipment loss are reduced, the operation risk and the production cost are reduced, and the transition time is shortened. The method is simple to operate and easy to implement.
Disclosure of Invention
Aiming at the current situations that the device is shut down or the operation steps are complicated and the transition time is long easily occurring in the process of switching different systems of catalysts in the current gas-phase polyethylene process, the invention provides the ethylene gas-phase polymerization grade switching agent, the device is not required to be newly added, the shutdown or the injection of catalyst poisons into a reactor is not required in the whole catalyst switching process, the replacement of a seed bed and the nitrogen pressure replacement are avoided, the material loss and the equipment loss are reduced, the operation risk and the production cost are reduced, and the transition time is shortened. The invention has simple operation and easy implementation.
The invention provides an ethylene gas phase polymerization grade switching agent, which is used for on-line switching of a titanium catalyst into a chromium catalyst in a gas phase polyethylene device, wherein the raw material of the ethylene gas phase polymerization grade switching agent comprises ammonium fluoride salt, aluminum stearate and an inorganic oxide dispersing agent, wherein the total content of the ammonium fluoride salt and the aluminum stearate is 0.1-10.0 wt%, the molar ratio of the ammonium fluoride salt to the aluminum stearate is 1-5: 1, and the content of the inorganic oxide dispersing agent is 90.0-99.9 wt%.
The ethylene gas phase polymerization grade switching agent is preferably characterized in that the ammonium fluoride salt is at least one of ammonium fluoride salt, tetrabutyl ammonium fluoride salt, ammonium bifluoride salt, ammonium hexafluosilicate salt, ammonium tetrabutyl difluorotriphenylsilicate salt and homologues of the ammonium salt.
In the ethylene gas phase polymerization grade switching agent, the inorganic oxide dispersing agent is preferably silicon dioxide subjected to high-temperature activation treatment or chemical activation treatment.
The ethylene gas phase polymerization grade switching agent is preferably prepared from silicon dioxide with the particle size of 1-100 mu m and the pore volume of 0.5-3.0 cm3A specific surface area of 100 to 500 m/g2/g。
The ethylene gas-phase polymerization grade switching agent of the invention is preferably characterized in that the high-temperature activation treatment comprises the following steps: drying the inorganic oxide dispersant and then heating for activation, wherein the heating for activation is carried out by raising the temperature from room temperature to 150-200 ℃ at a temperature raising rate of 5-10 min/DEG C, keeping the temperature for 3.0-5.0 h, then raising the temperature to 400-600 ℃ at 1-5 min/DEG C, keeping the temperature for 5.0-20.0 h, and finally cooling to room temperature at 5-20 min/DEG C; the whole activation process is protected by nitrogen.
Therefore, the invention also provides a preparation method of the ethylene gas-phase polymerization grade switching agent, which comprises the following steps:
(1) preparing ammonium fluoride salt and inert alkane into a solution at 20-30 ℃ to form mother liquor A;
(2) adding an inorganic oxide dispersant into the mother liquor A, stirring and dipping for 1-10 hours, pulping to obtain a mixture B, and activating the mixture B to obtain a solid dispersant C;
(3) preparing an aromatic hydrocarbon solution D with the aluminum stearate concentration of 1 mol%;
(4) and mixing the aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 10-24 hours at 20-30 ℃, filtering, and drying in an inert gas environment to obtain a finished product.
In the preparation method of the ethylene gas phase polymerization grade switching agent, the inert alkane solvent is preferably pentane, hexane, heptane, octane, benzene, toluene, xylene or isomers of the alkanes.
In the preparation method of the ethylene gas phase polymerization grade switching agent, the inert gas is preferably nitrogen.
In the preparation method of the ethylene gas phase polymerization grade switching agent, the aromatic hydrocarbon solution D is preferably a toluene solution.
The specific scheme of the invention is as follows:
the ethylene gas phase polymerization grade switching agent provided by the invention is used for on-line switching of a titanium catalyst into a chromium catalyst in a gas phase polyethylene device, and comprises ammonium fluoride salt, aluminum stearate and an inorganic oxide dispersing agent, wherein the total content of the ammonium fluoride salt and the aluminum stearate is 0.1-10.0%, the content of the inorganic oxide dispersing agent is 90.0-99.9%, and the molar ratio of the ammonium fluoride salt to the aluminum stearate is 1: 1; the preparation method comprises (1) preparing ammonium fluoride salt and inert alkane into inert alkane solution at room temperature to form mother liquor A; (2) adding an inorganic oxide dispersant into the mother liquor A, stirring and dipping for 1-10 hours, pulping to obtain a mixture B, and activating the mixture B to obtain a treated solid dispersant C; (3) preparing an aluminum stearate aromatic hydrocarbon solution D according to the molar ratio of the ammonium fluoride salt to the aluminum stearate of 1: 1; (4) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 10-24 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
The ethylene gas phase polymerization grade switching agent is characterized in that the particle size of the silicon dioxide after high-temperature activation is 1-100 mu m, and the pore volume is 0.5-3.0 cm3A specific surface area of 100 to 500 m/g2/g。
The ethylene gas-phase polymerization grade switching agent is characterized in that the high-temperature activation step is as follows: drying the inorganic oxide dispersant and then heating for activation, wherein the heating for activation is carried out by increasing the temperature from room temperature to 150-200 ℃ at a heating rate of 5-10 min/DEG C, keeping the temperature for 3.0-5.0 h, then keeping the temperature for 5.0-20.0 h from 1-5 min/DEG C to 400-600 ℃, and finally cooling to room temperature at 5-20 min/DEG C; the whole activation process is protected by nitrogen.
The preparation method of the ethylene gas-phase polymerization grade switching agent is characterized by comprising the following steps:
(1) preparing ammonium fluoride salt into inert alkane solution at room temperature to form mother liquor A;
(2) adding an inorganic oxide dispersant into the mother liquor A, stirring and dipping for 1-10 hours, pulping to obtain a mixture B, and activating the mixture B to obtain a treated solid dispersant C;
(3) weighing aluminum stearate according to the molar ratio of 1:1 of ammonium fluoride salt to aluminum stearate, and preparing an aromatic hydrocarbon solution D containing 1 mol% of aluminum stearate;
(4) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 10-24 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
The polyethylene gas-phase polymerization grade switching is mainly used for on-line switching of a titanium catalyst into a chromium catalyst in a gas-phase polyethylene device.
The invention has the beneficial effects that:
compared with the prior art, the ethylene gas-phase polymerization grade switching agent provided by the invention can be used for quickly and conveniently switching a gas-phase polyethylene device from a titanium catalyst product to a chromium catalyst product on line for production. The whole catalyst switching process does not need to replace a seedbed, does not need to stop the device, avoids nitrogen replacement and large-scale emptying of raw materials, and is simple to operate, easy to implement and short in transition time. Meanwhile, when the catalyst is switched, the grade switching agent can also adsorb a large amount of titanium catalysts added into the reactor before, ammonium fluoride in the ethylene gas phase polymerization grade switching agent can inactivate titanium active centers, the catalyst is prevented from forming fragments in a circulating system in the switching process, the risk of starting and stopping the device is reduced, and the balance pressure of upstream and downstream materials of the polyethylene device and the production fluctuation of the device can be effectively reduced.
Drawings
FIG. 1 is a schematic view of the structure of a fluidized bed polyethylene reactor for a gas phase process of the present invention
FIG. 2 is a diagram of the catalyst on-line switching procedure of the present invention.
Fig. 3 is a diagram of a conventional catalyst switching process.
In the figure:
1-a recycle gas compressor;
2-a recycle gas cooler;
3-discharging the intermediate tank;
4-a product bin;
5-a catalyst feeder;
6-gas phase fluidized bed reactor.
Detailed Description
The following examples illustrate the invention in detail: the present example is carried out on the premise of the technical scheme of the present invention, and detailed embodiments and processes are given, but the scope of the present invention is not limited to the following examples, and experimental methods without specific conditions noted in the following examples are generally performed under conventional conditions.
Example 1
Preparation of a brand switching agent:
(1) preparing 1kg of ammonium hexafluorosilicate into a hexane solution at room temperature to form a mother solution A;
(2) the mother liquor A was mixed with 50kg of 955 type silica carrier (average particle diameter 50 μm, pore volume 1.75 cm)3Per g, surface area 300m2Mixing the raw materials and stirring, soaking for 4 hours, and pulping to obtain a mixture B;
(3) the mixture B was subjected to activation treatment according to the procedure: the temperature rise activation process comprises raising the temperature from room temperature to 150 ℃ at a temperature rise rate of 5 min/DEG C, keeping the temperature for 4.0h, then keeping the temperature for 10.0h at a temperature of 5 min/DEG C to 600 ℃, and finally cooling to room temperature at a temperature of 10 min/DEG C; protecting the whole activation process by adopting nitrogen to obtain a treated solid dispersant C;
(4) weighing aluminum stearate according to the molar ratio of 1:1 of ammonium fluoride salt to aluminum stearate, and preparing an aromatic hydrocarbon solution D containing 1 mol% of aluminum stearate;
(5) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 20 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
(II) gas phase switching process:
FIG. 1 is a schematic view of a gas-phase fluidized-bed polyethylene reactor according to the present invention. The gas phase polymerization scheme in conjunction with FIG. 1 is: ethylene, hydrogen and high-pressure nitrogen are added into a circulating pipeline before starting, are compressed by a circulating gas compressor 1, and then are subjected to heat exchange by a circulating gas cooler 2, and enter a reactor from the bottom of a fluidized bed reactor 6. Full density polyethylene is produced in a gas phase fluidized bed reactor 6 under the action of a catalyst, the polyethylene product is free flowing granules, the index and molecular weight distribution of resin are controlled by selecting the catalyst and adjusting reaction conditions, and the product density is controlled by controlling the addition of comonomer. The generated polyethylene is discharged into a discharge intermediate tank 3 from the bottom of a gas-phase fluidized bed reactor 6, and after devolatilization treatment, entrained tail gas is discharged into a torch; the polyethylene product is discharged to a product silo 4 for storage.
A method for realizing the rapid switching from a titanium system catalyst to a chromium system catalyst in a 50kg/hr gas phase fluidized bed reactor comprises the following operation steps, the schematic diagram of which is shown in figure 2:
firstly, titanium catalyst feeding unit treatment: keeping the reaction components unchanged, stopping feeding the titanium catalyst and the reaction materials, discharging the residual titanium catalyst in the catalyst feeder 5 completely, and replacing the residual titanium catalyst by using nitrogen pressure of 0.7MPa for more than 10 times, wherein the process takes 1 hour;
processing residual catalyst in the reactor: adding an ethylene gas-phase polymerization grade switching agent into a catalyst feeder 5, and adding the ethylene gas-phase polymerization grade switching agent into the reactor according to the following grades: adding an ethylene gas phase polymerization grade switching agent into a gas phase fluidized bed reactor 6 according to the mass ratio of the feeding amount of the original titanium catalyst of 2:1, terminating the reaction of the titanium catalyst, terminating the reaction after 60 minutes, stopping adding the ethylene gas phase polymerization grade switching agent, discharging the residual ethylene gas phase polymerization grade switching agent in a catalyst feeder 5 completely, replacing the residual ethylene gas phase polymerization grade switching agent for more than 10 times by using nitrogen pressure of 0.7MPa, and consuming 2 hours in the process;
adjusting the components of the reactor: injecting an active promoter, namely triethylaluminum, into the gas-phase fluidized bed reactor 6, introducing reaction materials such as ethylene, hydrogen, nitrogen and a comonomer into the gas-phase fluidized bed reactor 6 again after 30 minutes, and starting component adjustment of the gas-phase fluidized bed reactor 6, wherein the process takes 2.5 hours;
fourthly, establishing reaction again: the chromium-based catalyst is added into a catalyst feeder 5, and the chromium-based catalyst is added to establish a reaction after the components of the gas-phase fluidized-bed reactor 6 are adjusted, wherein the process takes 0.5 hour.
The whole catalyst switching process does not need stopping, pressure replacement of reaction materials and replacement of a seed bed. The whole switching process takes about 6 hours, and is saved by 26 hours compared with the normal switching process of the catalyst.
Example 2
Preparation of a brand switching agent:
(1) preparing 1kg of tetrabutylammonium fluoride into a hexane solution at room temperature to form mother liquor A;
(2) the mother liquor A was mixed with 50kg of 955 type silica carrier (average particle diameter 50 μm, pore volume 1.75 cm)3Per g, surface area 300m2Mixing the raw materials and stirring, soaking for 4 hours, and pulping to obtain a mixture B;
(3) the mixture B was subjected to activation treatment according to the procedure: the temperature rise activation process comprises the steps of raising the temperature from room temperature to 150 ℃ at a temperature rise rate of 5 min/DEG C, keeping the temperature for 4.0h, keeping the temperature for 10.0h at a temperature rise rate of 5 min/DEG C to 600 ℃, and finally cooling to the room temperature at a temperature of 10 min/DEG C; protecting the whole activation process by adopting nitrogen to obtain a treated solid dispersant C;
(4) weighing aluminum stearate according to the molar ratio of 1:1 of ammonium fluoride salt to aluminum stearate, and preparing an aromatic hydrocarbon solution D containing 1 mol% of aluminum stearate;
(5) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 20 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
(II) gas phase switching process:
FIG. 1 is a schematic view of a gas-phase fluidized-bed polyethylene reactor according to the present invention. The gas phase polymerization process flow combined with FIG. 1 is: ethylene, hydrogen and high-pressure nitrogen are added into a circulating pipeline before start-up, are compressed by a circulating gas compressor 1, and then are subjected to heat exchange by a circulating gas cooler 2, and enter a reactor from the bottom of a fluidized bed reactor 6. Full density polyethylene is produced in a gas phase fluidized bed reactor 6 under the action of a catalyst, the polyethylene product is free flowing granules, the index and molecular weight distribution of resin are controlled by selecting the catalyst and adjusting reaction conditions, and the product density is controlled by controlling the addition of comonomer. The generated polyethylene is discharged into a discharge intermediate tank 3 from the bottom of a gas-phase fluidized bed reactor 6, and after devolatilization treatment, entrained tail gas is discharged into a torch; the polyethylene product is discharged to a product silo 4 for storage.
A method for realizing the rapid switching from a titanium system catalyst to a chromium system catalyst in a 50kg/hr gas phase fluidized bed reactor comprises the following operation steps, the schematic diagram of which is shown in figure 2:
firstly, titanium catalyst feeding unit treatment: keeping the reaction components unchanged, stopping feeding the titanium catalyst and the reaction materials, discharging the residual titanium catalyst in the catalyst feeder 5 completely, and replacing the residual titanium catalyst by using nitrogen pressure of 0.7MPa for more than 10 times, wherein the process takes 1 hour;
processing residual catalyst in the reactor: adding an ethylene gas-phase polymerization grade switching agent into a catalyst feeder 5, and adding the ethylene gas-phase polymerization grade switching agent into the reactor according to the following grades: adding an ethylene gas phase polymerization grade switching agent into a gas phase fluidized bed reactor 6 according to the mass ratio of the feeding amount of the original titanium catalyst of 5:1, terminating the reaction of the titanium catalyst, terminating the reaction after 30 minutes, stopping adding the ethylene gas phase polymerization grade switching agent, discharging the residual ethylene gas phase polymerization grade switching agent in a catalyst feeder 5 completely, replacing the residual ethylene gas phase polymerization grade switching agent for more than 10 times by using nitrogen pressure of 0.7MPa, and consuming 1.5 hours in the process;
adjusting the components of the reactor: injecting an active promoter, namely triethylaluminum, into the gas-phase fluidized bed reactor 6, introducing reaction materials such as ethylene, hydrogen, nitrogen and a comonomer into the gas-phase fluidized bed reactor 6 again after 30 minutes, and starting component adjustment of the gas-phase fluidized bed reactor 6, wherein the process takes 2.5 hours;
fourthly, establishing reaction again: the chromium-based catalyst is added into a catalyst feeder 5, and the chromium-based catalyst is added to establish a reaction after the components of the gas-phase fluidized-bed reactor 6 are adjusted, wherein the process takes 0.5 hour.
The whole catalyst switching process does not need stopping, pressure replacement of reaction materials and replacement of a seed bed. The whole switching process takes about 5.5 hours, and is saved by 26.5 hours compared with the normal switching process of the catalyst.
Example 3
Preparation of a brand switching agent:
(1) preparing 1kg of ammonium bifluoride into a hexane solution at room temperature to form mother liquor A;
(2) the mother liquor A was mixed with 50kg of 955 type silica carrier (average particle diameter 50 μm, pore volume 1.75 cm)3Per g, surface area 300m2Mixing the raw materials and stirring, soaking for 4 hours, and pulping to obtain a mixture B;
(3) the mixture B was subjected to activation treatment according to the procedure: the temperature rise activation process comprises raising the temperature from room temperature to 150 ℃ at a temperature rise rate of 5 min/DEG C, keeping the temperature for 4.0h, then keeping the temperature for 10.0h at a temperature of 5 min/DEG C to 600 ℃, and finally cooling to room temperature at a temperature of 10 min/DEG C; the whole activation process is protected by nitrogen to obtain a treated solid dispersing agent C;
(4) weighing aluminum stearate according to the molar ratio of 1:1 of ammonium fluoride salt to aluminum stearate, and preparing an aromatic hydrocarbon solution D containing 1 mol% of aluminum stearate;
(5) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 20 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
(II) gas phase switching process:
FIG. 1 is a schematic view of a gas-phase fluidized-bed polyethylene reactor according to the present invention. The gas phase polymerization scheme in conjunction with FIG. 1 is: ethylene, hydrogen and high-pressure nitrogen are added into a circulating pipeline before starting, are compressed by a circulating gas compressor 1, and then are subjected to heat exchange by a circulating gas cooler 2, and enter a reactor from the bottom of a fluidized bed reactor 6. Full density polyethylene is produced in a gas phase fluidized bed reactor 6 under the action of a catalyst, the polyethylene product is free flowing granules, the index and molecular weight distribution of resin are controlled by selecting the catalyst and adjusting reaction conditions, and the product density is controlled by controlling the addition of comonomer. The generated polyethylene is discharged into a discharge intermediate tank 3 from the bottom of a gas-phase fluidized bed reactor 6, and after devolatilization treatment, entrained tail gas is discharged into a torch; the polyethylene product is discharged to a product silo 4 for storage.
A method for achieving rapid switching from titanium-based to chromium-based catalysts in a 50kg/hr gas phase fluidized bed reactor 6 comprising the following operating steps, a schematic of which is shown in fig. 2:
firstly, titanium catalyst feeding unit treatment: keeping the reaction components unchanged, stopping feeding the titanium catalyst and the reaction materials, discharging the residual titanium catalyst in the catalyst feeder 5 completely, and replacing the residual titanium catalyst by using nitrogen pressure of 0.7MPa for more than 10 times, wherein the process takes 1 hour;
processing residual catalyst in the reactor: adding an ethylene gas-phase polymerization grade switching agent into a catalyst feeder 5, and adding the ethylene gas-phase polymerization grade switching agent into the reactor according to the following grades: adding an ethylene gas phase polymerization grade switching agent into a gas phase fluidized bed reactor 6 according to the mass ratio of the feeding amount of an original titanium catalyst of 8:1, terminating the reaction of the titanium catalyst, terminating the reaction after 30 minutes, stopping adding the ethylene gas phase polymerization grade switching agent, discharging the residual ethylene gas phase polymerization grade switching agent in a catalyst feeder 5 completely, replacing the residual ethylene gas phase polymerization grade switching agent for more than 10 times by using nitrogen pressure of 0.7MPa, and consuming 1.5 hours in the process;
adjusting the components of the reactor: injecting an active promoter, namely triethylaluminum, into the gas-phase fluidized bed reactor 6, introducing reaction materials such as ethylene, hydrogen, nitrogen and a comonomer into the gas-phase fluidized bed reactor 6 again after 30 minutes, and starting component adjustment of the gas-phase fluidized bed reactor 6, wherein the process takes 2.5 hours;
fourthly, establishing reaction again: the chromium-based catalyst is added into a catalyst feeder 5, and the chromium-based catalyst is added to establish a reaction after the components of the gas-phase fluidized-bed reactor 6 are adjusted, wherein the process takes 0.5 hour.
The whole catalyst switching process does not need stopping, pressure replacement of reaction materials and replacement of a seed bed. The whole switching process takes about 5.5 hours, and the time is saved by 27 hours compared with the normal switching process of the catalyst.
Example 4
Preparing a brand switching agent:
(1) preparing 1kg of ammonium fluoride into a hexane solution at room temperature to form a mother solution A;
(2) the mother liquor A was mixed with 50kg of 955 type silica carrier (average particle diameter 50 μm, pore volume 1.75 cm)3Per g, surface area 300m2Mixing the raw materials and stirring, soaking for 4 hours, and pulping to obtain a mixture B;
(3) the mixture B was subjected to activation treatment according to the procedure: the temperature rise activation process comprises raising the temperature from room temperature to 150 ℃ at a temperature rise rate of 5 min/DEG C, keeping the temperature for 4.0h, then keeping the temperature for 10.0h at a temperature of 5 min/DEG C to 600 ℃, and finally cooling to room temperature at a temperature of 10 min/DEG C; protecting the whole activation process by adopting nitrogen to obtain a treated solid dispersant C;
(4) weighing aluminum stearate according to the molar ratio of 1:1 of ammonium fluoride salt to aluminum stearate, and preparing an aromatic hydrocarbon solution D containing 1 mol% of aluminum stearate;
(5) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 20 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
(II) gas phase switching process:
FIG. 1 is a schematic view of a gas-phase fluidized-bed polyethylene reactor according to the present invention. The gas phase polymerization scheme in conjunction with FIG. 1 is: ethylene, hydrogen and high-pressure nitrogen are added into a circulating pipeline before starting, are compressed by a circulating gas compressor 1, and then are subjected to heat exchange by a circulating gas cooler 2, and enter a reactor from the bottom of a fluidized bed reactor 6. Full density polyethylene is produced in a gas phase fluidized bed reactor 6 under the action of a catalyst, the polyethylene product is free flowing granules, the index and molecular weight distribution of resin are controlled by selecting the catalyst and adjusting reaction conditions, and the product density is controlled by controlling the addition of comonomer. The generated polyethylene is discharged into a discharge intermediate tank 3 from the bottom of a gas-phase fluidized bed reactor 6, and after devolatilization treatment, entrained tail gas is discharged into a torch; the polyethylene product is discharged to a product silo 4 for storage.
A method for realizing the rapid switching from a titanium system to a chromium system catalyst in a 50kg/hr gas phase fluidized bed reactor 6 comprises the following operation steps, the schematic diagram of which is shown in figure 2:
firstly, titanium catalyst feeding unit treatment: keeping reaction components unchanged, stopping feeding of the titanium catalyst and reaction materials, discharging the residual titanium catalyst in the catalyst feeder 5 completely, and replacing the residual titanium catalyst for more than 10 times by using nitrogen pressure of 0.7MPa, wherein the process takes 1 hour;
processing residual catalyst in the reactor: adding an ethylene gas-phase polymerization grade switching agent into a catalyst feeder 5, and switching according to the grade: adding an ethylene gas phase polymerization grade switching agent into a gas phase fluidized bed reactor 6 according to the mass ratio of the feeding amount of the original titanium catalyst of 4:1, terminating the reaction of the titanium catalyst, terminating the reaction after 60 minutes, stopping feeding the ethylene gas phase polymerization grade switching agent, discharging the residual ethylene gas phase polymerization grade switching agent in a catalyst feeder 5 completely, replacing the residual ethylene gas phase polymerization grade switching agent for more than 10 times by using nitrogen pressure of 0.7MPa, and consuming 2 hours in the process;
adjusting the components of the reactor: injecting an active promoter, namely triethylaluminum, into the gas-phase fluidized bed reactor 6, introducing reaction materials such as ethylene, hydrogen, nitrogen and a comonomer into the gas-phase fluidized bed reactor 6 again after 30 minutes, and starting component adjustment of the gas-phase fluidized bed reactor 6, wherein the process takes 2.5 hours;
fourthly, establishing reaction again: the chromium-based catalyst is added into a catalyst feeder 5, and the chromium-based catalyst is added to establish a reaction after the components of the gas-phase fluidized-bed reactor 6 are adjusted, wherein the process takes 0.5 hour.
The whole catalyst switching process does not need stopping, pressure replacement of reaction materials and replacement of a seed bed. The whole switching process takes about 6 hours, and is saved by 26 hours compared with the normal switching process of the catalyst.
Example 5
Preparation of a brand switching agent:
(1) 1kg of tetrabutyl ammonium difluorotriphenylsilicate is prepared into a hexane solution at room temperature to form a mother solution A;
(2) the mother liquor A was mixed with 50kg of 955 type silica carrier (average particle diameter 50 μm, pore volume 1.75 cm)3Per g, surface area 300m2Mixing the raw materials and stirring, soaking for 4 hours, and pulping to obtain a mixture B;
(3) the mixture B was subjected to activation treatment according to the procedure: the temperature rise activation process comprises raising the temperature from room temperature to 150 ℃ at a temperature rise rate of 5 min/DEG C, keeping the temperature for 4.0h, then keeping the temperature for 10.0h at a temperature of 5 min/DEG C to 600 ℃, and finally cooling to room temperature at a temperature of 10 min/DEG C; the whole activation process is protected by nitrogen to obtain a treated solid dispersing agent C;
(4) weighing aluminum stearate according to the molar ratio of 1:1 of ammonium fluoride salt to aluminum stearate, and preparing an aromatic hydrocarbon solution D containing 1 mol% of aluminum stearate;
(5) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 20 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
(II) gas phase switching process:
FIG. 1 is a schematic view of a gas-phase fluidized-bed polyethylene reactor according to the present invention. The gas phase polymerization scheme in conjunction with FIG. 1 is: ethylene, hydrogen and high-pressure nitrogen are added into a circulating pipeline before starting, are compressed by a circulating gas compressor 1, and then are subjected to heat exchange by a circulating gas cooler 2, and enter a reactor from the bottom of a fluidized bed reactor 6. Full density polyethylene is produced in a gas phase fluidized bed reactor 6 under the action of a catalyst, the polyethylene product is free flowing granules, the index and molecular weight distribution of resin are controlled by selecting the catalyst and adjusting reaction conditions, and the product density is controlled by controlling the addition of comonomer. The generated polyethylene is discharged into a discharge intermediate tank 3 from the bottom of a gas-phase fluidized bed reactor 6, and after devolatilization treatment, entrained tail gas is discharged into a torch; the polyethylene product is discharged to a product silo 4 for storage.
A method for achieving rapid switching from titanium-based to chromium-based catalysts in a 50kg/hr gas phase fluidized bed reactor 6 comprising the following operating steps, a schematic of which is shown in fig. 2:
firstly, titanium catalyst feeding unit treatment: keeping the reaction components unchanged, stopping feeding the titanium catalyst and the reaction materials, discharging the residual titanium catalyst in the catalyst feeder 5 completely, and replacing the residual titanium catalyst by using nitrogen pressure of 0.7MPa for more than 10 times, wherein the process takes 1 hour;
processing residual catalyst in the reactor: adding an ethylene gas-phase polymerization grade switching agent into a catalyst feeder 5, and adding the ethylene gas-phase polymerization grade switching agent into the reactor according to the following grades: adding an ethylene gas phase polymerization grade switching agent into a gas phase fluidized bed reactor 6 according to the mass ratio of the feeding amount of the original titanium catalyst of 2:1, terminating the reaction of the titanium catalyst, terminating the reaction after 180 minutes, stopping adding the ethylene gas phase polymerization grade switching agent, discharging the residual ethylene gas phase polymerization grade switching agent in a catalyst feeder 5, replacing the residual ethylene gas phase polymerization grade switching agent for more than 10 times by using nitrogen pressure of 0.7MPa, and consuming 4 hours in the process;
adjusting the components of the reactor: injecting an active promoter, namely triethylaluminum, into the gas-phase fluidized bed reactor 6, introducing reaction materials such as ethylene, hydrogen, nitrogen and a comonomer into the gas-phase fluidized bed reactor 6 again after 30 minutes, and starting component adjustment of the gas-phase fluidized bed reactor 6, wherein the process takes 2.5 hours;
fourthly, establishing reaction again: the chromium-based catalyst is added into a catalyst feeder 5, and the chromium-based catalyst is added to establish a reaction after the components of the gas-phase fluidized-bed reactor 6 are adjusted, wherein the process takes 0.5 hour.
The whole catalyst switching process does not need stopping, pressure replacement of reaction materials and replacement of a seed bed. The whole switching process takes about 8 hours, and the time is saved by 24 hours compared with the normal switching process of the catalyst.
Example 6
Preparation of a brand switching agent:
(1) preparing 0.5kg of ammonium hexafluorosilicate into a hexane solution at room temperature to form a mother solution A;
(2) the mother liquor A was mixed with 50kg of 955 type silica carrier (average particle diameter 50 μm, pore volume 1.75 cm)3Per g, surface area 300m2Mixing the raw materials and stirring, soaking for 4 hours, and pulping to obtain a mixture B;
(3) the mixture B was subjected to activation treatment according to the procedure: the temperature rise activation process comprises raising the temperature from room temperature to 150 ℃ at a temperature rise rate of 5 min/DEG C, keeping the temperature for 4.0h, then keeping the temperature for 10.0h at a temperature of 5 min/DEG C to 600 ℃, and finally cooling to room temperature at a temperature of 10 min/DEG C; protecting the whole activation process by adopting nitrogen to obtain a treated solid dispersant C;
(4) weighing aluminum stearate according to the molar ratio of 1:1 of ammonium fluoride salt to aluminum stearate, and preparing an aromatic hydrocarbon solution D containing 1 mol% of aluminum stearate;
(5) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 20 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
(II) gas phase switching process:
FIG. 1 is a schematic view of a gas-phase fluidized-bed polyethylene reactor according to the present invention. The gas phase polymerization scheme in conjunction with FIG. 1 is: ethylene, hydrogen and high-pressure nitrogen are added into a circulating pipeline before starting, are compressed by a circulating gas compressor 1, and then are subjected to heat exchange by a circulating gas cooler 2, and enter a reactor from the bottom of a fluidized bed reactor 6. Full density polyethylene is produced in a gas phase fluidized bed reactor 6 under the action of a catalyst, the polyethylene product is free flowing granules, the index and molecular weight distribution of resin are controlled by selecting the catalyst and adjusting reaction conditions, and the product density is controlled by controlling the addition of comonomer. The generated polyethylene is discharged into a discharge intermediate tank 3 from the bottom of a gas-phase fluidized bed reactor 6, and after devolatilization treatment, entrained tail gas is discharged into a torch; the polyethylene product is discharged to a product silo 4 for storage.
A method for achieving rapid switching from titanium-based to chromium-based catalysts in a 50kg/hr gas phase fluidized bed reactor 6 comprising the following operating steps, a schematic of which is shown in fig. 2:
firstly, titanium catalyst feeding unit treatment: keeping the reaction components unchanged, stopping feeding the titanium catalyst and the reaction materials, discharging the residual titanium catalyst in the catalyst feeder 5 completely, and replacing the residual titanium catalyst by using nitrogen pressure of 0.7MPa for more than 10 times, wherein the process takes 1 hour;
processing residual catalyst in the reactor: adding an ethylene gas-phase polymerization grade switching agent into a catalyst feeder 5, and adding the ethylene gas-phase polymerization grade switching agent into the reactor according to the following grades: adding an ethylene gas phase polymerization grade switching agent into a gas phase fluidized bed reactor 6 according to the mass ratio of the feeding amount of an original titanium catalyst of 6:1, terminating the reaction of the titanium catalyst, terminating the reaction after 60 minutes, stopping adding the ethylene gas phase polymerization grade switching agent, discharging the residual ethylene gas phase polymerization grade switching agent in a catalyst feeder 5, replacing the residual ethylene gas phase polymerization grade switching agent for more than 10 times by using nitrogen pressure of 0.7MPa, and consuming 2 hours in the process;
adjusting the components of the reactor: injecting an active promoter, namely triethylaluminum, into the gas-phase fluidized bed reactor 6, introducing reaction materials such as ethylene, hydrogen, nitrogen and a comonomer into the gas-phase fluidized bed reactor 6 again after 30 minutes, and starting component adjustment of the gas-phase fluidized bed reactor 6, wherein the process takes 2.5 hours;
fourthly, establishing reaction again: the chromium-based catalyst is added into a catalyst feeder 5, and the chromium-based catalyst is added to establish a reaction after the components of the gas-phase fluidized-bed reactor 6 are adjusted, wherein the process takes 0.5 hour.
The whole catalyst switching process does not need stopping, pressure replacement of reaction materials and replacement of a seed bed. The whole switching process takes about 6 hours, and is saved by 26 hours compared with the normal switching process of the catalyst.
Example 7
Preparation of a brand switching agent:
(1) preparing 1.5kg of ammonium hexafluorosilicate into a hexane solution at room temperature to form a mother solution A;
(2) the mother liquor A was mixed with 50kg of 955 type silica carrier (average particle diameter 50 μm, pore volume 1.75 cm)3Per g, surface area 300m2Mixing the raw materials and stirring, soaking for 4 hours, and pulping to obtain a mixture B;
(3) the mixture B was subjected to activation treatment according to the procedure: the temperature rise activation process comprises raising the temperature from room temperature to 150 ℃ at a temperature rise rate of 5 min/DEG C, keeping the temperature for 4.0h, then keeping the temperature for 10.0h at a temperature of 5 min/DEG C to 600 ℃, and finally cooling to room temperature at a temperature of 10 min/DEG C; protecting the whole activation process by adopting nitrogen to obtain a treated solid dispersant C;
(4) weighing aluminum stearate according to the molar ratio of 1:1 of ammonium fluoride salt to aluminum stearate, and preparing an aromatic hydrocarbon solution D containing 1 mol% of aluminum stearate;
(5) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 20 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
(II) gas phase switching process:
FIG. 1 is a schematic view of a gas-phase fluidized-bed polyethylene reactor according to the present invention. The gas phase polymerization scheme in conjunction with FIG. 1 is: ethylene, hydrogen and high-pressure nitrogen are added into a circulating pipeline before starting, are compressed by a circulating gas compressor 1, and then are subjected to heat exchange by a circulating gas cooler 2, and enter a reactor from the bottom of a fluidized bed reactor 6. Full density polyethylene is produced in a gas phase fluidized bed reactor 6 under the action of a catalyst, the polyethylene product is free flowing granules, the index and molecular weight distribution of resin are controlled by selecting the catalyst and adjusting reaction conditions, and the product density is controlled by controlling the addition of comonomer. The generated polyethylene is discharged into a discharge intermediate tank 3 from the bottom of a gas-phase fluidized bed reactor 6, and after devolatilization treatment, entrained tail gas is discharged into a torch; the polyethylene product is discharged to a product silo 4 for storage.
The method for realizing the rapid switching from the titanium-based catalyst to the chromium-based catalyst in the 50kg/hr gas-phase fluidized bed reactor 6 comprises the following operation steps, the schematic diagram of which is shown in figure 2:
firstly, titanium catalyst feeding unit treatment: keeping the reaction components unchanged, stopping feeding the titanium catalyst and the reaction materials, discharging the residual titanium catalyst in the catalyst feeder 5 completely, and replacing the residual titanium catalyst by using nitrogen pressure of 0.7MPa for more than 10 times, wherein the process takes 1 hour;
processing residual catalyst in the reactor: adding an ethylene gas-phase polymerization grade switching agent into a catalyst feeder 5, and adding the ethylene gas-phase polymerization grade switching agent into the reactor according to the following grades: adding an ethylene gas phase polymerization grade switching agent into a gas phase fluidized bed reactor 6 according to the mass ratio of the feeding amount of the original titanium catalyst of 3:1, terminating the reaction of the titanium catalyst, terminating the reaction after 30 minutes, stopping adding the ethylene gas phase polymerization grade switching agent, discharging the residual ethylene gas phase polymerization grade switching agent in a catalyst feeder 5 completely, replacing the residual ethylene gas phase polymerization grade switching agent for more than 10 times by using nitrogen pressure of 0.7MPa, and consuming 1.5 hours in the process;
adjusting the components of the reactor: injecting an active promoter, namely triethylaluminum, into the gas-phase fluidized bed reactor 6, introducing reaction materials such as ethylene, hydrogen, nitrogen and a comonomer into the gas-phase fluidized bed reactor 6 again after 30 minutes, and starting component adjustment of the gas-phase fluidized bed reactor 6, wherein the process takes 2.5 hours;
fourthly, establishing reaction again: the chromium-based catalyst is added into a catalyst feeder 5, and the chromium-based catalyst is added to establish a reaction after the components of the gas-phase fluidized-bed reactor 6 are adjusted, wherein the process takes 0.5 hour.
The whole catalyst switching process does not need stopping, pressure replacement of reaction materials and replacement of a seed bed. The whole switching process takes about 5.5 hours, and is saved by 26.5 hours compared with the normal switching process of the catalyst.
Example 8
Preparation of a brand switching agent:
(1) preparing 2.0kg of ammonium hexafluorosilicate into a hexane solution at room temperature to form a mother solution A;
(2) the mother liquor A was mixed with 50kg of 955 type silica carrier (average particle diameter 50 μm, pore volume 1.75 cm)3Per g, surface area 300m2Mixing the raw materials and stirring, soaking for 4 hours, and pulping to obtain a mixture B;
(3) the mixture B was subjected to activation treatment according to the procedure: the temperature rise activation process comprises raising the temperature from room temperature to 150 ℃ at a temperature rise rate of 5 min/DEG C, keeping the temperature for 4.0h, then keeping the temperature for 10.0h at a temperature of 5 min/DEG C to 600 ℃, and finally cooling to room temperature at a temperature of 10 min/DEG C; the whole activation process is protected by nitrogen to obtain a treated solid dispersing agent C;
(4) weighing aluminum stearate according to the molar ratio of 1:1 of ammonium fluoride salt to aluminum stearate, and preparing an aromatic hydrocarbon solution D containing 1 mol% of aluminum stearate;
(5) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 20 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
(II) gas phase switching process:
FIG. 1 is a schematic view of a gas-phase fluidized-bed polyethylene reactor according to the present invention. The gas phase polymerization scheme in conjunction with FIG. 1 is: ethylene, hydrogen and high-pressure nitrogen are added into a circulating pipeline before starting, are compressed by a circulating gas compressor 1, and then are subjected to heat exchange by a circulating gas cooler 2, and enter a reactor from the bottom of a fluidized bed reactor 6. Full density polyethylene is produced in a gas phase fluidized bed reactor 6 under the action of a catalyst, the polyethylene product is free flowing granules, the index and molecular weight distribution of resin are controlled by selecting the catalyst and adjusting reaction conditions, and the product density is controlled by controlling the addition of comonomer. The generated polyethylene is discharged into a discharge intermediate tank 3 from the bottom of a gas-phase fluidized bed reactor 6, and after devolatilization treatment, entrained tail gas is discharged into a torch; the polyethylene product is discharged to a product silo 4 for storage.
A method for achieving rapid switching from titanium-based to chromium-based catalysts in a 50kg/hr gas phase fluidized bed reactor 6 comprising the following operating steps, a schematic of which is shown in fig. 2:
firstly, titanium catalyst feeding unit treatment: keeping the reaction components unchanged, stopping feeding the titanium catalyst and the reaction materials, discharging the residual titanium catalyst in the catalyst feeder 5 completely, and replacing the residual titanium catalyst by using nitrogen pressure of 0.7MPa for more than 10 times, wherein the process takes 1 hour;
processing residual catalyst in the reactor: adding an ethylene gas-phase polymerization grade switching agent into a catalyst feeder 5, and adding the ethylene gas-phase polymerization grade switching agent into the reactor according to the following grades: adding an ethylene gas phase polymerization grade switching agent into a gas phase fluidized bed reactor 6 according to the mass ratio of the feeding amount of the original titanium catalyst of 20:1, terminating the reaction of the titanium catalyst, terminating the reaction after 30 minutes, stopping adding the ethylene gas phase polymerization grade switching agent, discharging the residual ethylene gas phase polymerization grade switching agent in a catalyst feeder 5 completely, replacing the residual ethylene gas phase polymerization grade switching agent for more than 10 times by using nitrogen pressure of 0.7MPa, and consuming 1.5 hours in the process;
adjusting the components of the reactor: injecting an active promoter, namely triethylaluminum, into the gas-phase fluidized bed reactor 6, introducing reaction materials such as ethylene, hydrogen, nitrogen and a comonomer into the gas-phase fluidized bed reactor 6 again after 300 minutes, and starting component adjustment of the gas-phase fluidized bed reactor 6, wherein the process takes 7 hours;
fourthly, establishing the reaction again: the chromium-based catalyst is added into a catalyst feeder 5, and the chromium-based catalyst is added to establish a reaction after the components of the gas-phase fluidized-bed reactor 6 are adjusted, wherein the process takes 0.5 hour.
The whole catalyst switching process does not need stopping, pressure replacement of reaction materials and replacement of a seed bed. The whole switching process takes about 10 hours, and is saved by 22 hours compared with the normal switching process of the catalyst.
Example 9
Preparation of a brand switching agent:
(1) preparing 5.0kg of ammonium hexafluorosilicate into a hexane solution at room temperature to form a mother solution A;
(2) mother liquor A was mixed with 50kg 955 type silica support (average particle size 50 μm, pore volume 1.75 cm)3Per g, surface area 300m2Mixing the raw materials and stirring, soaking for 4 hours, and pulping to obtain a mixture B;
(3) the mixture B was subjected to activation treatment according to the procedure: the temperature rise activation process comprises raising the temperature from room temperature to 150 ℃ at a temperature rise rate of 5 min/DEG C, keeping the temperature for 4.0h, then keeping the temperature for 10.0h at a temperature of 5 min/DEG C to 600 ℃, and finally cooling to room temperature at a temperature of 10 min/DEG C; protecting the whole activation process by adopting nitrogen to obtain a treated solid dispersant C;
(4) weighing aluminum stearate according to the molar ratio of 1:1 of ammonium fluoride salt to aluminum stearate, and preparing an aromatic hydrocarbon solution D containing 1 mol% of aluminum stearate;
(5) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 20 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
(II) gas phase switching process:
FIG. 1 is a schematic view of a gas-phase fluidized-bed polyethylene reactor according to the present invention. The gas phase polymerization scheme in conjunction with FIG. 1 is: ethylene, hydrogen and high-pressure nitrogen are added into a circulating pipeline before starting, are compressed by a circulating gas compressor 1, and then are subjected to heat exchange by a circulating gas cooler 2, and enter a reactor from the bottom of a fluidized bed reactor 6. Full density polyethylene is produced in a gas phase fluidized bed reactor 6 under the action of a catalyst, the polyethylene product is free flowing granules, the index and molecular weight distribution of resin are controlled by selecting the catalyst and adjusting reaction conditions, and the product density is controlled by controlling the addition of comonomer. The generated polyethylene is discharged into a discharge intermediate tank 3 from the bottom of a gas-phase fluidized bed reactor 6, and after devolatilization treatment, entrained tail gas is discharged into a torch; the polyethylene product is discharged to a product silo 4 for storage.
The method for realizing the rapid switching from the titanium-based catalyst to the chromium-based catalyst in the 50kg/hr gas-phase fluidized bed reactor 6 comprises the following operation steps, the schematic diagram of which is shown in figure 2:
firstly, titanium catalyst feeding unit treatment: keeping the reaction components unchanged, stopping feeding the titanium catalyst and the reaction materials, discharging the residual titanium catalyst in the catalyst feeder 5 completely, and replacing the residual titanium catalyst by using nitrogen pressure of 0.7MPa for more than 10 times, wherein the process takes 1 hour;
processing residual catalyst in the reactor: adding an ethylene gas-phase polymerization grade switching agent into a catalyst feeder 5, and adding the ethylene gas-phase polymerization grade switching agent into the reactor according to the following grades: adding an ethylene gas phase polymerization grade switching agent into a gas phase fluidized bed reactor 6 according to the mass ratio of the feeding amount of the original titanium catalyst of 100:1, terminating the reaction of the titanium catalyst, terminating the reaction after 30 minutes, stopping adding the ethylene gas phase polymerization grade switching agent, discharging the residual ethylene gas phase polymerization grade switching agent in a catalyst feeder 5 completely, replacing the residual ethylene gas phase polymerization grade switching agent for more than 10 times by using nitrogen pressure of 0.7MPa, and consuming 1.5 hours in the process;
adjusting the components of the reactor: injecting an active promoter, namely triethylaluminum, into the gas-phase fluidized-bed reactor 6, introducing reaction materials such as ethylene, hydrogen, nitrogen and a comonomer into the gas-phase fluidized-bed reactor 6 again after 25 hours, and starting component adjustment of the gas-phase fluidized-bed reactor 6, wherein the process takes 27 hours;
fourthly, establishing reaction again: the chromium-based catalyst is added into a catalyst feeder 5, and the chromium-based catalyst is added to establish a reaction after the components of the gas-phase fluidized-bed reactor 6 are adjusted, wherein the process takes 0.5 hour.
The whole catalyst switching process does not need stopping, pressure replacement of reaction materials and replacement of a seed bed. The whole switching process takes about 30 hours, and the time is saved by 2 hours compared with the normal switching procedure of the catalyst.
Example 10
Preparation of a brand switching agent:
(1) preparing 1.0kg of ammonium hexafluorosilicate into a hexane solution at room temperature to form a mother solution A;
(2) mother liquor A was mixed with 50kg of a silica support of the W.R.Grace's 957HS type (average particle size 40 μm, pore volume 1.45 cm)3Per g, surface area 300m2/g) mixing, stirring and soaking for 4 hoursPulping to obtain a mixture B;
(3) the mixture B was subjected to activation treatment according to the procedure: the temperature rise activation process comprises raising the temperature from room temperature to 150 ℃ at a temperature rise rate of 5 min/DEG C, keeping the temperature for 4.0h, then keeping the temperature for 10.0h at a temperature of 5 min/DEG C to 600 ℃, and finally cooling to room temperature at a temperature of 10 min/DEG C; protecting the whole activation process by adopting nitrogen to obtain a treated solid dispersant C;
(4) weighing aluminum stearate according to the molar ratio of 1:1 of ammonium fluoride salt to aluminum stearate, and preparing an aromatic hydrocarbon solution D containing 1 mol% of aluminum stearate;
(5) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 20 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
(II) gas phase switching process:
FIG. 1 is a schematic view of a gas-phase fluidized-bed polyethylene reactor according to the present invention. The gas phase polymerization scheme in conjunction with FIG. 1 is: ethylene, hydrogen and high-pressure nitrogen are added into a circulating pipeline before starting, are compressed by a circulating gas compressor 1, and then are subjected to heat exchange by a circulating gas cooler 2, and enter a reactor from the bottom of a fluidized bed reactor 6. Full density polyethylene is produced in a gas phase fluidized bed reactor 6 under the action of a catalyst, the polyethylene product is free flowing granules, the index and molecular weight distribution of resin are controlled by selecting the catalyst and adjusting reaction conditions, and the product density is controlled by controlling the addition of comonomer. The generated polyethylene is discharged into a discharge intermediate tank 3 from the bottom of a gas-phase fluidized bed reactor 6, and after devolatilization treatment, entrained tail gas is discharged into a torch; the polyethylene product is discharged to a product silo 4 for storage.
The method for realizing the rapid switching from the titanium-based catalyst to the chromium-based catalyst in the 50kg/hr gas-phase fluidized bed reactor 6 comprises the following operation steps, the schematic diagram of which is shown in figure 2:
firstly, titanium catalyst feeding unit treatment: keeping the reaction components unchanged, stopping feeding the titanium catalyst and the reaction materials, discharging the residual titanium catalyst in the catalyst feeder 5 completely, and replacing the residual titanium catalyst by using nitrogen pressure of 0.7MPa for more than 10 times, wherein the process takes 1 hour;
processing residual catalyst in the reactor: adding an ethylene gas-phase polymerization grade switching agent into a catalyst feeder 5, and adding the ethylene gas-phase polymerization grade switching agent into the reactor according to the following grades: adding an ethylene gas phase polymerization grade switching agent into a gas phase fluidized bed reactor 6 according to the mass ratio of the feeding amount of the original titanium catalyst of 4:1, terminating the reaction of the titanium catalyst, terminating the reaction after 150 minutes, stopping adding the ethylene gas phase polymerization grade switching agent, discharging the residual ethylene gas phase polymerization grade switching agent in a catalyst feeder 5 completely, replacing the residual ethylene gas phase polymerization grade switching agent for more than 10 times by using nitrogen pressure of 0.7MPa, and consuming 3.5 hours in the process;
adjusting the components of the reactor: injecting an active promoter, namely triethylaluminum, into the gas-phase fluidized bed reactor 6, introducing reaction materials such as ethylene, hydrogen, nitrogen and a comonomer into the gas-phase fluidized bed reactor 6 again after 30 minutes, and starting component adjustment of the gas-phase fluidized bed reactor 6, wherein the process takes 2.5 hours;
fourthly, establishing reaction again: the chromium-based catalyst is added into a catalyst feeder 5, and the chromium-based catalyst is added to establish a reaction after the components of the gas-phase fluidized-bed reactor 6 are adjusted, wherein the process takes 0.5 hour.
The whole catalyst switching process does not need stopping, pressure replacement of reaction materials and replacement of a seed bed. The whole switching process takes about 7.5 hours, and the time is saved by 24.5 hours compared with the normal switching process of the catalyst.
Example 11
Preparation of a brand switching agent:
(1) preparing 1.0kg of ammonium hexafluorosilicate into a hexane solution at room temperature to form a mother solution A;
(2) mother liquor A was mixed with 50kg of PQ 35100 type silica carrier (average particle diameter 90 μm, pore volume 3.02 cm)3Per g, surface area 500m2Mixing the raw materials and stirring, soaking for 4 hours, and pulping to obtain a mixture B;
(3) the mixture B was subjected to activation treatment according to the procedure: the temperature rise activation process comprises raising the temperature from room temperature to 150 ℃ at a temperature rise rate of 5 min/DEG C, keeping the temperature for 4.0h, then keeping the temperature for 10.0h at a temperature of 5 min/DEG C to 600 ℃, and finally cooling to room temperature at a temperature of 10 min/DEG C; protecting the whole activation process by adopting nitrogen to obtain a treated solid dispersant C;
(4) weighing aluminum stearate according to the molar ratio of 1:1 of ammonium fluoride salt to aluminum stearate, and preparing an aromatic hydrocarbon solution D containing 1 mol% of aluminum stearate;
(5) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 20 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
(II) gas phase switching process:
FIG. 1 is a schematic view of a gas-phase fluidized-bed polyethylene reactor according to the present invention. The gas phase polymerization scheme in conjunction with FIG. 1 is: ethylene, hydrogen and high-pressure nitrogen are added into a circulating pipeline before starting, are compressed by a circulating gas compressor 1, and then are subjected to heat exchange by a circulating gas cooler 2, and enter a reactor from the bottom of a fluidized bed reactor 6. Full density polyethylene is produced in a gas phase fluidized bed reactor 6 under the action of a catalyst, the polyethylene product is free flowing granules, the index and molecular weight distribution of resin are controlled by selecting the catalyst and adjusting reaction conditions, and the product density is controlled by controlling the addition of comonomer. The generated polyethylene is discharged into a discharge intermediate tank 3 from the bottom of a gas-phase fluidized bed reactor 6, and after devolatilization treatment, entrained tail gas is discharged into a torch; the polyethylene product is discharged to a product silo 4 for storage.
A method for achieving rapid switching from titanium-based to chromium-based catalysts in a 50kg/hr gas phase fluidized bed reactor 6 comprising the following operating steps, a schematic of which is shown in fig. 2:
firstly, titanium catalyst feeding unit treatment: keeping reaction components unchanged, stopping feeding of the titanium catalyst and reaction materials, discharging the residual titanium catalyst in the catalyst feeder 5 completely, and replacing the residual titanium catalyst for more than 10 times by using nitrogen pressure of 0.7MPa, wherein the process takes 1 hour;
processing residual catalyst in the reactor: adding an ethylene gas-phase polymerization grade switching agent into a catalyst feeder 5, and adding the ethylene gas-phase polymerization grade switching agent into the reactor according to the following grades: adding an ethylene gas phase polymerization grade switching agent into a gas phase fluidized bed reactor 6 according to the mass ratio of the feeding amount of the original titanium catalyst of 1:1, terminating the reaction of the titanium catalyst, terminating the reaction after 120 minutes, stopping adding the ethylene gas phase polymerization grade switching agent, discharging the residual ethylene gas phase polymerization grade switching agent in a catalyst feeder 5, replacing the residual ethylene gas phase polymerization grade switching agent by using nitrogen gas pressure of 0.7MPa for more than 10 times, and consuming 3.0 hours in the process;
adjusting the components of the reactor: injecting an active promoter, namely triethylaluminum, into the gas-phase fluidized bed reactor 6, introducing reaction materials such as ethylene, hydrogen, nitrogen and a comonomer into the gas-phase fluidized bed reactor 6 again after 30 minutes, and starting component adjustment of the gas-phase fluidized bed reactor 6, wherein the process takes 2.5 hours;
fourthly, establishing reaction again: the chromium-based catalyst is added into a catalyst feeder 5, and the chromium-based catalyst is added to establish a reaction after the components of the gas-phase fluidized-bed reactor 6 are adjusted, wherein the process takes 0.5 hour.
The whole catalyst switching process does not need stopping, pressure replacement of reaction materials and replacement of a seed bed. The whole switching process takes about 7 hours, and the time is saved by 25 hours compared with the normal switching process of the catalyst.
Example 12
Preparation of a brand switching agent:
(1) preparing 1.0kg of ammonium hexafluorosilicate into a hexane solution at room temperature to form a mother solution A;
(2) mother liquor A was mixed with 50kg of a silica support of the W.R.Grace's 955 type (average particle size 50 μm, pore volume 1.75 cm)3Per g, surface area 300m2Mixing the raw materials and stirring, soaking for 8 hours, and pulping to obtain a mixture B;
(3) the mixture B was subjected to activation treatment according to the procedure: the temperature rise activation process comprises raising the temperature from room temperature to 150 ℃ at a temperature rise rate of 5 min/DEG C, keeping the temperature for 4.0h, then keeping the temperature for 10.0h at a temperature of 5 min/DEG C to 600 ℃, and finally cooling to room temperature at a temperature of 10 min/DEG C; protecting the whole activation process by adopting nitrogen to obtain a treated solid dispersant C;
(4) weighing aluminum stearate according to the molar ratio of 1:1 of ammonium fluoride salt to aluminum stearate, and preparing an aromatic hydrocarbon solution D containing 1 mol% of aluminum stearate;
(5) and mixing the aluminum stearate aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 10 hours at room temperature, and sequentially filtering and drying in an inert gas environment to obtain a finished product.
(II) gas phase switching process:
FIG. 1 is a schematic view of a gas-phase fluidized-bed polyethylene reactor according to the present invention. The gas phase polymerization scheme in conjunction with FIG. 1 is: ethylene, hydrogen and high-pressure nitrogen are added into a circulating pipeline before starting, are compressed by a circulating gas compressor 1, and then are subjected to heat exchange by a circulating gas cooler 2, and enter a reactor from the bottom of a fluidized bed reactor 6. Full density polyethylene is produced in a gas phase fluidized bed reactor 6 under the action of a catalyst, the polyethylene product is free flowing granules, the index and molecular weight distribution of resin are controlled by selecting the catalyst and adjusting reaction conditions, and the product density is controlled by controlling the addition of comonomer. The generated polyethylene is discharged into a discharge intermediate tank 3 from the bottom of a gas-phase fluidized bed reactor 6, and after devolatilization treatment, entrained tail gas is discharged into a torch; the polyethylene product is discharged to a product silo 4 for storage.
A method for achieving rapid switching from titanium-based to chromium-based catalysts in a 50kg/hr gas phase fluidized bed reactor 6 comprising the following operating steps, a schematic of which is shown in fig. 2:
firstly, titanium catalyst feeding unit treatment: keeping the reaction components unchanged, stopping feeding the titanium catalyst and the reaction materials, discharging the residual titanium catalyst in the catalyst feeder 5 completely, and replacing the residual titanium catalyst by using nitrogen pressure of 0.7MPa for more than 10 times, wherein the process takes 1 hour;
processing residual catalyst in the reactor: adding an ethylene gas-phase polymerization grade switching agent into a catalyst feeder 5, and adding the ethylene gas-phase polymerization grade switching agent into the reactor according to the following grades: adding an ethylene gas phase polymerization grade switching agent into a gas phase fluidized bed reactor 6 according to the mass ratio of the feeding amount of the original titanium catalyst of 2:1, terminating the reaction of the titanium catalyst, terminating the reaction after 30 minutes, stopping adding the ethylene gas phase polymerization grade switching agent, discharging the residual ethylene gas phase polymerization grade switching agent in a catalyst feeder 5 completely, replacing the residual ethylene gas phase polymerization grade switching agent for more than 10 times by using nitrogen pressure of 0.7MPa, and consuming 1.5 hours in the process;
adjusting the components of the reactor: injecting an active promoter triethylboron into the gas-phase fluidized-bed reactor 6, introducing reaction materials such as ethylene, hydrogen, nitrogen and comonomer into the gas-phase fluidized-bed reactor 6 again after 90 minutes, and starting component adjustment of the gas-phase fluidized-bed reactor 6, wherein the process takes 3.5 hours;
fourthly, establishing reaction again: the chromium-based catalyst is added into a catalyst feeder 5, and the chromium-based catalyst is added to establish a reaction after the components of the gas-phase fluidized-bed reactor 6 are adjusted, wherein the process takes 0.5 hour.
The whole catalyst switching process does not need stopping, pressure replacement of reaction materials and replacement of a seed bed. The whole switching process takes about 6.5 hours, and the time is saved by 25.5 hours compared with the normal switching process of the catalyst.
Comparative example 1:
the normal switching procedure from titanium to chromium catalysts was carried out in a 50kg/hr gas phase fluidized bed reactor, comprising the following steps, a schematic of which is shown in fig. 3:
(1) stopping feeding of the titanium catalyst and the reaction materials, replacing residual components in the reactor with nitrogen, injecting a terminator into the reactor to terminate the reaction, simultaneously discharging the residual titanium catalyst in the catalyst feeder, and replacing for more than 10 times with nitrogen pressure of 0.7MPa, wherein the process takes 1 hour.
(2) The discharge procedure was started and the titanium-based polyethylene seed bed in the reactor was completely discharged, which took 1 hour.
(3) The reactor was replaced with 0.7MPa of nitrogen, and when no terminator could be detected in the reactor, the apparatus replacement was judged to be acceptable, and this process took 3 hours.
(4) And (3) conveying the required chromium polyethylene seedbed into the reactor again, simultaneously heating the reactor, introducing nitrogen for replacement, and starting the dehydration treatment of the seedbed, wherein the process takes 24 hours.
(5) Adding a chromium catalyst into a catalyst feeder, simultaneously introducing reaction materials such as ethylene, hydrogen, nitrogen, comonomer and the like into the reactor again for feeding, starting component adjustment of the reactor, and after the component adjustment of the reactor is finished, adding the chromium catalyst to establish a reaction, wherein the process takes 2 hours.
The entire catalyst switching process requires shut down, pressure replacement of the reaction mass, and replacement of the seedbed, with a normal catalyst switching procedure taking approximately 32 hours.
The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore intended that all such changes and modifications as fall within the true spirit and scope of the invention be considered as within the following claims.
Claims (9)
1. The ethylene gas-phase polymerization grade switching agent is used for on-line switching of a titanium catalyst into a chromium catalyst in a gas-phase polyethylene device, and is characterized in that the raw materials of the ethylene gas-phase polymerization grade switching agent consist of ammonium fluoride salt, aluminum stearate and an inorganic oxide dispersing agent, wherein the total content of the ammonium fluoride salt and the aluminum stearate is 0.1-10.0 wt%, the molar ratio of the ammonium fluoride salt to the aluminum stearate is 1-5: 1, and the content of the inorganic oxide dispersing agent is 90.0-99.9 wt%.
2. The gas phase ethylene polymerization grade switch according to claim 1, wherein the ammonium fluoride salt is at least one of ammonium fluoride salt, tetrabutylammonium fluoride salt, ammonium bifluoride salt, ammonium hexafluosilicate salt, ammonium tetrabutyldifluorotriphenylsilicate salt and homologues thereof.
3. The ethylene gas-phase polymerization grade switching agent as claimed in claim 1, wherein the inorganic oxide dispersant is silica subjected to high temperature activation treatment or chemical activation treatment.
4. The ethylene gas phase polymerization grade switching agent as claimed in claim 3, wherein the particle diameter of the silica is 1 to 100 μm, and the pore volume is 0.5 to 3.0cm3A specific surface area of 100 to 500 m/g2/g。
5. The ethylene gas-phase polymerization grade switching agent as claimed in claim 3, wherein the high-temperature activation treatment comprises the steps of: drying the inorganic oxide dispersant and then heating for activation, wherein the heating for activation is carried out by raising the temperature from room temperature to 150-200 ℃ at a temperature raising rate of 5-10 min/DEG C, keeping the temperature for 3.0-5.0 h, then raising the temperature to 400-600 ℃ at 1-5 min/DEG C, keeping the temperature for 5.0-20.0 h, and finally cooling to room temperature at 5-20 min/DEG C; the whole activation process is protected by nitrogen.
6. A process for preparing a gas-phase polymerization grade switching agent of ethylene as claimed in claim 1, which comprises the steps of:
(1) preparing ammonium fluoride salt and inert alkane into a solution at 20-30 ℃ to form mother liquor A;
(2) adding an inorganic oxide dispersant into the mother liquor A, stirring and dipping for 1-10 hours, pulping to obtain a mixture B, and activating the mixture B to obtain a solid dispersant C;
(3) preparing an aromatic hydrocarbon solution D with the aluminum stearate concentration of 1 mol%;
(4) and mixing the aromatic hydrocarbon solution D with the solid dispersant C, stirring and reacting for 10-24 hours at 20-30 ℃, filtering, and drying in an inert gas environment to obtain a finished product.
7. The method for preparing a grade switch agent for ethylene gas phase polymerization as claimed in claim 6, wherein the inert alkane solvent is pentane, hexane, heptane, octane, benzene, toluene, xylene, or isomers of the above alkanes.
8. The method for preparing a grade switch agent for ethylene gas phase polymerization as claimed in claim 6, wherein the inert gas is nitrogen.
9. The method for preparing a grade switching agent for ethylene gas phase polymerization as claimed in claim 6, wherein the aromatic hydrocarbon solution D is a toluene solution.
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