CN114478876A - Method for producing polyethylene by adopting intermittent liquid phase method and polyethylene - Google Patents
Method for producing polyethylene by adopting intermittent liquid phase method and polyethylene Download PDFInfo
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Abstract
The invention belongs to the field of olefin, and relates to a method for producing polyethylene by adopting a batch liquid phase method and the polyethylene. The method comprises the following steps: 1) putting propane and a catalyst into a polymerization kettle; 2) heating the polymerization kettle to a preset polymerization temperature, and introducing ethylene gas into the polymerization kettle to perform polymerization reaction; 3) after the polymerization reaction is finished, reducing the pressure of the polymerization kettle to vaporize unreacted ethylene and propane in the polymerization kettle, condensing the obtained gas phase into a liquid phase material through a recovery condenser, and feeding the liquid phase material into a recovery tank; 4) and after recovery, spraying the materials in the polymerization kettle into a flash tank by utilizing the residual pressure in the polymerization kettle to obtain flash gas and polyethylene powder, and discharging the polyethylene powder after the flash gas is discharged to obtain the polyethylene. The method of the invention simplifies the polymerization section and the slurry post-treatment section, and avoids the problem of excessive transition materials in the continuous polyethylene production.
Description
Technical Field
The invention belongs to the field of olefin, and particularly relates to a method for producing polyethylene by adopting a batch liquid phase method, and the polyethylene prepared by the method.
Background
Polyethylene (PE) resin is a variety with the largest yield in general synthetic resin, has the characteristics of low price and good performance, and is widely applied to the fields of industry, agriculture and the like. Polyethylene production has been a coexistence of multiple process technologies. Current solution processes include medium pressure processes from Nova corporation, low pressure cooling processes from Dow chemical corporation, and low pressure adiabatic processes from DSM corporation. The slurry process includes Philips, Solvay's loop process and Hurst, Nissan chemical, Tri-well chemical stirred tank process. The gas phase process mainly comprises a Unipol process of Univariation company, an Innovene process of BP company and a Spherilene process of Basell company.
Ultra-high molecular weight polyethylene (UHMWPE) is a polyethylene resin with a molecular weight of 150 to 800 ten thousand. Compared with common polyethylene, UHMWPE has larger molecular weight, so that the UHMWPE has excellent performances of impact resistance, abrasion resistance, self-lubrication, low temperature resistance, chemical corrosion resistance and the like, and is widely applied to the fields of coal mining industry, chemical industry, mechanical industry, textile industry, medical materials such as artificial limbs and other fields. The UHMWPE resin production process is similar to the production of common high-density polyethylene HDPE, and can adopt the HDPE production technology to produce, but the difference is that the UHMWPE production does not have a granulation procedure, and the product is powdery. The preparation method of the ultra-high molecular weight polyethylene resin mainly adopts a Ziegler low-pressure slurry method, namely, beta-TiCl3/Al(C2H5)2Cl or TiCl4/Al(C2H5)2Cl is used as main catalyst, triethyl aluminium is used as cocatalyst, saturated hydrocarbon at 60-120 deg.C is used as dispersing medium, and ethylene is reacted at a certain temp. and pressurePolymerizing under the condition of force to prepare products with different molecular weights.
The UHMWPE can be obtained by reducing the hydrogen concentration by using conventional polyethylene production processes. However, the conventional polyethylene production process is a continuous process. In the continuous production process, when UHMWPE resin is produced, common polyethylene products with molecular weight of 5-15 ten thousand need to be switched to UHMWPE resin; it is also necessary to switch from UHMWPE resin to ordinary polyethylene after production is complete. The switching period in the production process is long, and the produced transition materials are more. And low molecular weight polyethylene is mixed into the UHMWPE resin, reducing the quality of the product.
CN105440184A discloses a preparation method of high-density polyethylene with bimodal molecular weight distribution. The technological process of the method is that the double-component catalyst is prepared first, and the double-component catalyst and ethylene are subjected to liquid phase intermittent polymerization reaction in two serially connected polymerization reactors, and the prepared polyethylene with bimodal molecular weight distribution has outstanding processing performance, mechanical property and wear resistance compared with unimodal polyethylene, so that the application field of polyethylene in plastic products is expanded, and the resin can be used for preparing mineral powder and special wear-resistant pipe for slurry conveying. The invention adopts hexane as solvent to carry out slurry polymerization, therefore, slurry obtained after the polymerization is completed must be separated into filter cake and mother liquor by a centrifuge, and the filter cake is dried into powder to obtain the polyethylene product. The equipment for centrifugation and drying is expensive and the production cycle is long.
CN104356261A discloses a continuous flash equilibrium method for batch polymerization of ultra-high molecular weight polyethylene. The method adopts two polymerization kettles which are set with a certain time difference and are operated in parallel, one polymerization kettle is unloaded, the other polymerization kettle is reacted, unreacted ethylene is released through unloading flash evaporation, hexane is condensed and recovered, pressurized gaseous ethylene is compressed and returned to the polymerization kettle which is in reaction, and the unreacted ethylene is recycled. The invention avoids the problems that the low-pressure ethylene which does not participate in the reaction in the prior art is difficult to return to a polymerization kettle for recycling, only enters a torch for burning, causes serious ethylene waste, is not environment-friendly and has potential safety hazard. The solvent hexane is used, subsequent slurry containing hexane and ultrahigh molecular weight polyethylene particles still needs to be separated into filter cakes and mother liquor by a centrifugal machine, the filter cakes are dried into powder to obtain polyethylene products, and the production period is long.
CN108264599A discloses a production system and a process for preparing ultra-high molecular weight polyethylene by a batch slurry process. The process system consists of a polymerization kettle, a catalyst hopper, an activator hopper, a condensate separating tank, a condenser, a circulating fan, a flash evaporation kettle, an ethylene feeding flow control system, a propane feeding system, a reaction control system, a propylene feeding system and an activator metering feeding system; the process comprises a raw and auxiliary material feeding flow, a polymerization flow, a recovery treatment flow and a product treatment flow. The production system and the production process avoid the procedures of filtering, drying, refining and the like required by the traditional solvents such as hexane, solvent oil, butane and the like used in the traditional ultra-high molecular weight polyethylene slurry process, and reduce the production cost. The process adopts propane as solvent, avoids the procedures of separation by a centrifuge, drying and the like, and simplifies the slurry treatment procedure. However, a condensate separating tank, a condenser, a circulating fan and other equipment must be additionally arranged on the polymerization kettle, so that the process of the polymerization section is complex, and the production cost is increased.
Disclosure of Invention
In view of the above problems, the present invention provides a method for producing polyethylene by a batch process and polyethylene produced by the method. The method can simplify the polymerization section and the slurry post-treatment section when producing polyethylene, especially ultra-high molecular weight polyethylene, and avoid the problem of excessive transition materials in the continuous polyethylene production.
In a first aspect the present invention provides a process for the production of polyethylene by a batch liquid phase process, the process comprising the steps of:
1) putting propane and a catalyst into a polymerization kettle;
2) heating the polymerization kettle to a preset polymerization temperature, and introducing ethylene gas into the polymerization kettle to perform polymerization reaction;
3) after the polymerization reaction is finished, reducing the pressure of the polymerization kettle to vaporize unreacted ethylene and propane in the polymerization kettle, condensing the obtained gas phase into a liquid phase material through a recovery condenser, and feeding the liquid phase material into a recovery tank;
4) after recovery, spraying the materials in the polymerization kettle into a flash tank by utilizing the residual pressure in the polymerization kettle to obtain flash gas and polyethylene powder, and discharging the polyethylene powder after discharging the flash gas to obtain polyethylene;
wherein optionally hydrogen is fed into the polymerization vessel in step 1) or before ethylene gas is fed into the polymerization vessel in step 2).
A second aspect of the invention provides a polyethylene prepared by the above process.
The method for producing polyethylene of the invention effectively solves the problem that continuous production plants are difficult to produce ultra-high molecular weight polyethylene by using commonly used Ziegler-Natta catalysts. The production process of the present invention does not suffer from the problem of excess transition material encountered in continuous process polyethylene production plants. Due to the batch process, virtually no transition material is present.
The intermittent liquid phase bulk method production equipment adopted by the invention only needs to install the feeding pipeline of the ethylene and the instrument valve for controlling the flow on the existing equipment of the existing small bulk polypropylene production plant, and the process equipment is slightly changed, so the method is easy to implement, and the economic benefit of the plant for producing the polypropylene by using the intermittent liquid phase method can be effectively improved.
The production method of the invention adopts propane as the suspension solvent, compared with the traditional slurry process which uses hexane, solvent oil and other traditional solvents, the production method does not need the process steps of centrifugation, filtration, drying and the like, and does not need a centrifuge, a dryer and other equipment, thereby reducing the production cost.
Compared with the existing intermittent method for producing polyethylene by using propane as a solvent, the production method disclosed by the invention has the advantages that additional devices such as a condensate separating tank, a condenser and a circulating fan are not required, and the cost is reduced.
The modified polypropylene production equipment of the small-body polypropylene production plant is used for producing polyethylene, particularly ultra-high molecular weight polyethylene, and is very suitable for meeting the characteristic that downstream manufacturers need small-batch goods. The ultra-high molecular weight polyethylene has higher price, and the technology of the invention can obviously improve the economic benefit of small-body polypropylene production plants.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
Exemplary embodiments of the present invention will be described in more detail by referring to the accompanying drawings.
FIG. 1 is a schematic view of a batch liquid phase bulk process production apparatus used in the process for producing polyethylene according to the present invention.
1. A polymerization kettle; 2. a recovery condenser; 3. a recovery tank; 4. a flash tank; 5. a gas holder.
a. Ethylene; b. propane; c. nitrogen gas; d. polyethylene powder products.
Detailed Description
The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The invention provides a method for producing polyethylene by adopting a batch liquid phase method, which comprises the following steps:
1) putting propane and a catalyst into a polymerization kettle;
2) heating the polymerization kettle to a preset polymerization temperature, and introducing ethylene gas into the polymerization kettle to perform polymerization reaction;
3) after the polymerization reaction is finished, reducing the pressure of the polymerization kettle to vaporize unreacted ethylene and propane in the polymerization kettle, condensing the obtained gas phase into a liquid phase material through a recovery condenser, and feeding the liquid phase material into a recovery tank;
4) after recovery, spraying materials in the polymerization kettle into a flash tank by using residual pressure in the polymerization kettle to obtain flash gas and polyethylene powder, and discharging the polyethylene powder after discharging the flash gas to obtain polyethylene;
wherein optionally hydrogen is fed into the polymerization vessel in step 1) or before ethylene gas is fed into the polymerization vessel in step 2).
The invention can adjust the adding amount of hydrogen or not add hydrogen according to the requirement to adjust the melt mass flow rate of the polyethylene product. When hydrogen is added in step 1), it is generally first added to the polymerization vessel, followed by liquid propane to add the catalyst to the polymerization vessel and, optionally, the remainder of the propane required for the process. Or adding part of propane, adding the catalyst into the polymerization kettle by liquid propane, and finally supplementing the insufficient part of propane.
According to a preferred embodiment of the present invention, the polymerizer is provided with a jacket for heating and heat-removing the polymerizer to control the polymerization temperature within a predetermined temperature range. Typically, warming the polymerization vessel is accomplished by passing hot water through the jacket of the polymerization vessel; heat removal from the polymerization vessel was achieved by feeding cold water to the jacket of the polymerization vessel. Specifically, in the temperature rising process, a hot water pump is adopted to send hot water to a jacket of a polymerization kettle for heating and rising the temperature, the kettle temperature is raised from the normal temperature to the polymerization temperature, the polymerization temperature is 50-90 ℃, and preferably 60-80 ℃; when the temperature rises to the preset polymerization temperature, ethylene gas is introduced into the polymerization kettle, and the polymerization reaction is started. The pressure of the polymerization kettle is controlled by ethylene, and the pressure of the polymerization reaction is 2.3-3.8 MPa, preferably 2.8-3.6 MPa. After the temperature rises to the preset polymerization temperature, the hot water (which is gradually closed in an automatic state) is switched into circulating cooling water (the opening of a circulating cooling water valve is automatically adjusted), the heat released by the polymerization reaction is removed, and the reaction temperature is controlled to be stable.
According to the method of the invention, in step 3), after the polymerization reaction is finished (generally, the polymerization time is required or the yield of polyethylene is required), unreacted ethylene and propane in the system are vaporized by reducing the pressure of the polymerization kettle, so as to realize the first-step separation and recovery, wherein the reduction of the pressure of the polymerization kettle is realized by opening a valve connecting the polymerization kettle and a recovery system (namely, opening the recovery system), and the recovery system comprises the recovery condenser and the recovery tank. The recycling condenser can adopt circulating cooling water at the temperature of 20-30 ℃, and the pressure of the recycling tank is controlled to be 0.8-1.8 MPa, preferably 1.0-1.5 MPa by discharging non-condensable gas. The discharged non-condensable gas is mainly ethylene and hydrogen, and can be uniformly recycled by a factory. Usually, the recovery tank is at room temperature, in the initial stage of recovery, the gas phase in the polymerization kettle continuously enters the recovery tank from the polymerization kettle, and after equilibrium, recovery is finished. At this time, the residual pressure in the polymerization kettle is still remained, preferably, the residual pressure in the polymerization kettle is 0.8 to 1.8MPa, preferably 1.0 to 1.5 MPa.
In the step 3) of the method, the liquid phase material which is vaporized and condensed in the polymerization kettle and then enters the recovery tank is mainly propane and contains a small amount of ethylene, and the liquid phase material can be used as a polymerization raw material again.
In the step 4) of the method, the flash gas needs to be discharged so as to reduce the adsorption quantity of the combustible gas in the polyethylene powder and realize the second step of separation and recovery. Specific methods of discharging the flash gas: firstly, pressure relief is carried out to a gas holder: opening a valve between the flash tank and the gas holder to discharge gas in the flash tank into the gas holder, and reducing the pressure of the flash tank to the pressure of the gas holder; then, vacuumizing or nitrogen replacement is adopted to further reduce the combustible gas in the polyethylene powder, and the pumped gas or the gas after nitrogen replacement also enters a gas cabinet. The gas in the gas holder is recycled or treated harmlessly according to small-body polypropylene production factory equipment. The vacuumizing time or the nitrogen replacement times are based on the standard that the content of combustible gas in the flash tank is qualified. And when the content of combustible gas in the flash tank is qualified, discharging the polyethylene powder out of the flash tank, and feeding the polyethylene powder into a powder bin or packaging the polyethylene powder. And then, testing the melt mass flow rate and the like of the powder product, and grading the product according to the test result.
The catalyst used in the process of the present invention is a polyethylene catalyst, and may be any catalyst capable of polymerizing ethylene into high molecular weight polyethylene, such as a metallocene catalyst or a Ziegler-Natta catalyst, and preferably a Ziegler-Natta catalyst is used.
Further preferably, said Ziegler-Natta catalyst comprises: (1) a titanium-containing solid catalyst active component containing magnesium, titanium, halogen and an internal electron donor; (2) an organoaluminum compound co-catalyst component; and (3) optionally an external electron donor component.
The solid catalyst available for use may be purchased from the okada division of beijing, china petrochemical catalyst limited, such as: BCE catalyst, CM catalyst.
The organoaluminum compound as the co-catalyst component of the catalyst is preferably an alkylaluminum compound, more preferably at least one member selected from the group consisting of trialkylaluminums (e.g., trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, trioctylaluminum, etc.), diethylaluminum monochloride, diisobutylaluminum monochloride, ethylaluminum dichloride and ethylaluminum dichloride.
The ratio of the titanium-containing solid catalyst active component to the organoaluminum compound co-catalyst component may be 0.1:25 to 0.1:1000 in terms of Ti/Al molar ratio.
The amount of each component used in the present invention is not particularly limited and may be determined as desired, and for example, the amount of the catalyst may be determined in accordance with the single pot yield and the catalyst activity. Propane as suspending solvent may also be used in conventional solvent amounts.
According to the regulations of GB/T21461.1-2008, ultra-high molecular weight polyethylene (PE-UHMW) refers to a polyethylene material with a melt Mass Flow Rate (MFR) of less than 0.1g/10min at a temperature of 190 ℃ and a load of 21.6 kg. The invention can adjust the adding amount of hydrogen according to the requirement, or adjust the melt mass flow rate without adding hydrogen. The process of the present invention is particularly suitable for the production of ultra high molecular weight polyethylene.
The invention also provides polyethylene prepared by the method. Preferably, the polyethylene is ultra-high molecular weight polyethylene.
The present invention will be further described with reference to the following examples, but the scope of the present invention is not limited to these examples.
The experimental results in the examples were obtained according to the following test methods, which are all operated at room temperature environment without particular limitation:
the main catalyst is BCE catalyst, and is obtained from the Odada division of Beijing of China petrochemical catalyst Co.
The catalyst promoter component is triethyl aluminum, and is prepared into 0.35mol/L for use.
Melt Mass Flow Rate (MFR): measured according to GB/T3682.1-2018 at 190 ℃ under a load of 2.16 kg.
Density: measured according to the method described in GB/T1033.2-2010.
The following examples all employ a batch liquid phase bulk process production apparatus as shown in FIG. 1. The equipment comprises a polymerization kettle 1, a recovery condenser 2, a recovery tank 3, a flash tank 4 and a gas holder 5, wherein the top of the polymerization kettle 1 is sequentially connected with the recovery condenser 2 and the recovery tank 3, the bottom of the polymerization kettle 1 is connected with the flash tank 4, and the top of the flash tank 4 is connected with the gas holder 5; ethylene feed line, propane feed line are connected with polymerizer 1 respectively, and nitrogen gas feed line and flash tank 4 sub-unit connection, and flash tank 4 bottom is provided with polyethylene powder product discharge line, wherein retrieve condenser 2 with retrieve jar 3 constitution recovery system, ethylene feed line, propane feed line, nitrogen gas feed line, polyethylene powder product discharge line, all be provided with the valve on the pipeline between polymerizer 1 and the recovery system, the pipeline between polymerizer 1 and flash tank 4, the pipeline between flash tank 4 and the gas holder 5.
The polymerization vessel 1 had a volume of 5L and was externally provided with a jacket (not shown). The recycling condenser adopts circulating cooling water with the temperature of 20-25 ℃.
Example 1
Hydrogen was added to the polymerization vessel to raise the vessel pressure to 0.4MPa, and 26.8mg of BCE catalyst and 10.0ml of triethylaluminum solution were charged into the polymerization vessel with 2.0 liters of propane at room temperature. Heating the polymerization kettle by jacket hot water of the polymerization kettle, when the temperature of the polymerization kettle reaches 70 ℃, increasing the gauge pressure of the polymerization kettle to 3.2MPa, adding ethylene to increase the pressure of the polymerization kettle to 3.5MPa, and starting to carry out polymerization reaction; the flow rate of the cooling water is adjusted according to the temperature of the polymerization kettle, so that the polymerization temperature is maintained. After the polymerization reaction is carried out for 150 minutes, a valve for connecting a polymerization kettle and a recovery system is opened, the pressure of the polymerization kettle is released, unreacted ethylene and propane are vaporized in the polymerization kettle, the obtained gas phase is condensed into a liquid phase material by a recovery condenser, and the liquid phase material enters a recovery tank; when the kettle pressure is reduced to 1.5MPa, the recovery is stopped. Discharging the gas and the polyethylene powder in the kettle into a flash tank, opening a valve between the flash tank and a gas cabinet to discharge the gas in the flash tank into the gas cabinet, reducing the pressure of the flash tank to normal pressure, then filling nitrogen to 0.4MPa, then discharging the gas after nitrogen replacement into the gas cabinet, discharging the powder in the tank and weighing after 3 times of nitrogen replacement, thus obtaining 455g of polyethylene powder. The powder was tested and the results are shown in Table 1.
Example 2
Hydrogen was added to the polymerization vessel to raise the vessel pressure to 0.6MPa, and 25.7mg of BCE catalyst and 10.0ml of triethylaluminum solution were charged into the polymerization vessel with 2.0 liters of propane at room temperature. Heating the reaction kettle by jacket hot water of the polymerization kettle, when the temperature of the polymerization kettle reaches 65 ℃, increasing the gauge pressure of the polymerization kettle to 3.0MPa, adding ethylene to increase the pressure of the polymerization kettle to 3.3MPa, and starting polymerization reaction; the flow rate of the cooling water is adjusted according to the temperature of the polymerization kettle, so that the polymerization temperature is maintained. After the polymerization reaction is carried out for 150 minutes, a valve for connecting a polymerization kettle and a recovery system is opened, the pressure of the polymerization kettle is released, unreacted ethylene and propane are vaporized in the polymerization kettle, the obtained gas phase is condensed into a liquid phase material by a recovery condenser, and the liquid phase material enters a recovery tank; when the kettle pressure is reduced to 1.5MPa, the recovery is stopped. Discharging the gas and the polyethylene powder in the kettle into a flash tank, opening a valve between the flash tank and a gas cabinet, discharging the gas in the flash tank into the gas cabinet, reducing the pressure of the flash tank to normal pressure, then charging nitrogen to 0.4MPa, then discharging the gas after nitrogen replacement into the gas cabinet, discharging the powder in the tank after nitrogen replacement is carried out for 3 times, and weighing to obtain 285g of polyethylene powder. The powder was tested and the results are shown in Table 1.
Example 3
Hydrogen was added to the polymerization vessel to raise the vessel pressure to 1.0MPa, and 26.3mg of BCE catalyst and 10.0ml of triethylaluminum solution were charged into the polymerization vessel with 2.0 liters of propane at room temperature. Heating the polymerization kettle by jacket hot water of the polymerization kettle, when the temperature of the polymerization kettle reaches 70 ℃, increasing the gauge pressure of the polymerization kettle to 3.4MPa, adding ethylene to increase the pressure of the polymerization kettle to 3.6MPa, and starting to carry out polymerization reaction; the flow rate of the cooling water is adjusted according to the temperature of the polymerization kettle, so that the polymerization temperature is maintained. After the polymerization reaction is carried out for 150 minutes, a valve for connecting a polymerization kettle and a recovery system is opened, the pressure of the polymerization kettle is released, unreacted ethylene and propane are vaporized in the polymerization kettle, the obtained gas phase is condensed into a liquid phase material by a recovery condenser, and the liquid phase material enters a recovery tank; when the kettle pressure is reduced to 1.5MPa, the recovery is stopped. Discharging the gas and the polyethylene powder in the kettle into a flash tank, opening a valve between the flash tank and a gas cabinet to discharge the gas in the flash tank into the gas cabinet, reducing the pressure of the flash tank to normal pressure, then filling nitrogen to 0.4MPa, then discharging the gas after nitrogen replacement into the gas cabinet, discharging the powder in the tank and weighing to obtain 246g of polyethylene powder after nitrogen replacement is carried out for 3 times. The powder was tested and the results are shown in Table 1.
Comparative example
23.0mg of BCE catalyst and 10.0ml of triethylaluminum solution were charged into a polymerization vessel with 2.0 liters of hexane at room temperature, and the vessel pressure was raised to 0.6MPa by adding hydrogen. Heating the polymerization kettle by jacket hot water of the polymerization kettle, when the temperature of the polymerization kettle reaches 70 ℃, increasing the gauge pressure of the polymerization kettle to 0.7MPa, adding ethylene to increase the pressure of the polymerization kettle to 0.8MPa, and starting polymerization reaction; the flow rate of the cooling water is adjusted according to the temperature of the polymerization vessel, thereby maintaining the polymerization temperature. After the polymerization reaction is carried out for 150 minutes, a valve connecting the polymerization kettle and the gas holder is opened, the polymerization kettle is decompressed, and the unreacted ethylene enters the gas holder. Discharging the hexane and polyethylene powder in the kettle into a flash tank, and pumping out the hexane in the kettle through a filter screen. Then nitrogen gas with the flow rate of 100ml/min is introduced, the powder is purged for 12 hours, and the powder in the tank is discharged and weighed to obtain 266g of polyethylene powder. The powder was tested and the results are shown in Table 1.
TABLE 1 analysis results of powder lot
In the comparative example, nitrogen purging is required for a long time to remove the hexane solvent, and thus, the method of the invention obviously reduces the production time of single-kettle polyethylene.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
Claims (11)
1. A process for producing polyethylene by a batch liquid phase process, comprising the steps of:
1) putting propane and a catalyst into a polymerization kettle;
2) heating the polymerization kettle to a preset polymerization temperature, and introducing ethylene gas into the polymerization kettle to perform polymerization reaction;
3) after the polymerization reaction is finished, reducing the pressure of the polymerization kettle to vaporize unreacted ethylene and propane in the polymerization kettle, condensing the obtained gas phase into a liquid phase material through a recovery condenser, and feeding the liquid phase material into a recovery tank;
4) after recovery, spraying the materials in the polymerization kettle into a flash tank by utilizing the residual pressure in the polymerization kettle to obtain flash gas and polyethylene powder, and discharging the polyethylene powder after discharging the flash gas to obtain polyethylene;
wherein optionally hydrogen is fed into the polymerization vessel in step 1) or before ethylene gas is fed into the polymerization vessel in step 2).
2. The process according to claim 1, wherein in step 2), the polymerization temperature is 50 to 90 ℃, preferably 60 to 80 ℃; the pressure of the polymerization reaction is 2.3 to 3.8MPa, preferably 2.8 to 3.6 MPa.
3. The process as claimed in claim 1, wherein the polymerizer is provided with a jacket for temperature elevation and heat withdrawal of the polymerizer to control the polymerization temperature within a predetermined temperature range.
4. The method of claim 1, wherein in step 3), the reducing the polymerizer pressure is achieved by opening a valve connecting the polymerizer with a recovery system comprising the recovery condenser and the recovery tank.
5. The process of claim 1, wherein in step 3), the liquid phase feed to the recovery tank is optionally returned to the polymerizer as a feed.
6. The method according to claim 1, wherein in step 4), the residual pressure in the polymerization kettle is 0.8 to 1.8MPa, preferably 1.0 to 1.5 MPa.
7. The method as claimed in claim 1, wherein in the step 4), the flash gas is discharged by decompression to a gas holder and then vacuumization or nitrogen replacement is carried out; the pumped flash gas or the gas after nitrogen replacement enters a gas holder.
8. Process according to any one of claims 1 to 7, wherein the catalyst is a Ziegler-Natta catalyst, preferably comprising: (1) a titanium-containing solid catalyst active component containing magnesium, titanium, halogen and an internal electron donor; (2) an organoaluminum compound co-catalyst component; and (3) optionally an external electron donor component.
9. The process of claim 8, wherein the ratio of the titanium-containing solid catalyst active component to the organoaluminum compound co-catalyst component is 0.1:25 to 0.1:1000 in terms of Ti/Al molar ratio.
10. The method of claim 1, wherein the polyethylene is ultra-high molecular weight polyethylene.
11. Polyethylene, preferably ultra high molecular weight polyethylene, obtainable by the process according to any one of claims 1 to 10.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103804556A (en) * | 2012-11-07 | 2014-05-21 | 中国石油化工股份有限公司 | Olefin polymerization method, an ethylene polymer, and preparation method of ethylene polymer |
| US20160107955A1 (en) * | 2014-10-16 | 2016-04-21 | Spolek Pro Chemickou A Hutni Vyrobu A.S. | Process for producing a chlorinated c3-6 alkane |
| CN108264599A (en) * | 2018-03-20 | 2018-07-10 | 南京金陵塑胶化工有限公司 | Batch process slurry process prepares the production system and technique of ultra-high molecular weight polyethylene |
-
2020
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103804556A (en) * | 2012-11-07 | 2014-05-21 | 中国石油化工股份有限公司 | Olefin polymerization method, an ethylene polymer, and preparation method of ethylene polymer |
| US20160107955A1 (en) * | 2014-10-16 | 2016-04-21 | Spolek Pro Chemickou A Hutni Vyrobu A.S. | Process for producing a chlorinated c3-6 alkane |
| CN108264599A (en) * | 2018-03-20 | 2018-07-10 | 南京金陵塑胶化工有限公司 | Batch process slurry process prepares the production system and technique of ultra-high molecular weight polyethylene |
Non-Patent Citations (2)
| Title |
|---|
| 刘淑强: "《化学纤维制备》", 上海：东华大学出版社 * |
| 杜宏斌;王子强;陶俭;陈新;: "高效CM催化剂在UHMWPE生产中的应用", 合成树脂及塑料 * |
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