CN114409832A - Electrostatic control method for olefin polymerization process - Google Patents

Electrostatic control method for olefin polymerization process Download PDF

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CN114409832A
CN114409832A CN202210092023.4A CN202210092023A CN114409832A CN 114409832 A CN114409832 A CN 114409832A CN 202210092023 A CN202210092023 A CN 202210092023A CN 114409832 A CN114409832 A CN 114409832A
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antistatic compound
polyolefin powder
nascent
antistatic
polymerization process
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杨遥
范子雄
葛世轶
黄正梁
王靖岱
阳永荣
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ZJU Hangzhou Global Scientific and Technological Innovation Center
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    • 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
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Abstract

The invention discloses a static control method for an olefin polymerization process, which comprises the steps of mixing nascent state polyolefin powder with an antistatic compound at the temperature of 30-60 ℃, standing for 24-72 hours to obtain nascent state polyolefin powder loaded with the antistatic compound; when the electrostatic voltage is increased to the electrostatic voltage threshold value in the olefin polymerization process, introducing the nascent state polyolefin powder loaded with the antistatic compound into a polymerization reactor filled with polyolefin powder through cascade control so as to control the electrostatic voltage in the olefin polymerization process. The method can reduce the dispersion time of the antistatic agent in the gas-phase polymerization reactor, and has less loss, thereby having higher electricity eliminating effect and stability.

Description

Electrostatic control method for olefin polymerization process
Technical Field
The invention belongs to the technical field of olefin polymerization, and particularly relates to a static control method for an olefin polymerization process.
Background
In the industrial production of polyolefins, the dry reaction environment in the gas phase polymerization reactor and the high insulation of polyolefins result in frequent triboelectrification and slow static dissipation, providing natural conditions for the generation and accumulation of static electricity. The existence of static electricity in the production process can cause potential hazards such as wall sticking, caking and the like, and even cause the occurrence of reactor failure and explosion accidents. Therefore, antistatic agents are widely used in industrial fluidized bed reactors to control static electricity.
U.S. Pat. No. 5, 5034480A discloses a process for preparing ultra high molecular weight ethylene polymers using antistatic agents such as chromium salts of alkyl salicylic acids in titanium based catalyst systems, resulting in products that are free of fouling in the polymerization reactor. EP0560035 discloses a polymerization process using an alkyldiethanolamine to selectively inhibit polymerization on polymer particles smaller than 850 μm, thereby eliminating or reducing the build-up of polymer particles on the inner wall of a gas phase polymerization reactor caused by static electricity. U.S. Pat. No. 5, 6894127, 2 discloses a process for preventing reactor fouling and reducing temperature discontinuities around walls in the gas phase polymerization of olefins using an adjuvant comprising a polysulfone copolymer, a polymeric polyamine and an oil-soluble sulfonic acid.
The antistatic agents are introduced directly into the polymerization reactor in the above-mentioned patent documents. In addition to direct introduction, there are also processes in which the antistatic compound is premixed with other substances (catalysts) and then introduced into the polymerization reactor. WO2012041810a1 discloses a process for preparing a catalyst suspension comprising a surfactant-type antistatic compound and transferring said catalyst suspension to a polymerization reactor, reducing the risk of fouling inside the polymerization reactor.
The direct or indirect addition of the antistatic compound to the polymerization reactor in the continuous polymerization of olefins using the above method, although effective in reducing the production static electricity during the reaction, has a disadvantage in that the addition of the liquid-phase antistatic compound affects the flow pattern of the fluid in the polymerization reactor and is easily carried out or left on the wall surface of the reactor during the polymerization reaction, resulting in some loss of the liquid-phase antistatic compound. In addition, the high boiling point of liquid antistatic agents makes them generally incapable of vaporizing in a polymerization environment, and the poor flowability also makes them incapable of atomizing, and antistatic effects are severely restricted by antistatic agents that are not sufficiently dispersed.
Therefore, it is desirable to design a new method for reducing static electricity in a polyolefin fluidized bed reactor, which is easy to implement, has good operability, and not only prevents the antistatic from being dispersed in a gas phase polymerization reactor for a long time, but also does not affect the flow pattern of the fluid in the polymerization reactor to prevent large loss and residue.
Disclosure of Invention
The invention provides a static control method for an olefin polymerization process, which can reduce the dispersion time of an antistatic agent in a gas-phase polymerization reactor and reduce loss, thereby having higher electricity eliminating effect and stability.
A method for electrostatic control of an olefin polymerization process, comprising:
(1) mixing the nascent polyolefin powder with an antistatic compound at 30-60 ℃, and standing for 24-72h to obtain the nascent polyolefin powder loaded with the antistatic compound;
(2) when the electrostatic voltage is increased to the electrostatic voltage threshold value in the olefin polymerization process, introducing the nascent state polyolefin powder loaded with the antistatic compound into a polymerization reactor filled with polyolefin powder through cascade control so as to control the electrostatic voltage in the olefin polymerization process.
Because the surface of the nascent state polyolefin powder has higher roughness and pore channels, the antistatic compound can be attached to the interior of the pore channels of the nascent state polyolefin powder, and then the nascent state polyolefin powder loaded with the antistatic compound participates in the powder mixing process in the olefin polymerization reactor in a solid state. The particles move violently and are mixed under the fluidization effect of high-speed gas in the reactor, the antistatic compound can slowly seep out from the inside of the pore channel, and the phenomenon that the antistatic compound is blown away due to the fact that the antistatic compound is attached to the surface of powder in a shallow layer when the antistatic compound is directly added is avoided, so that the antistatic effect is achieved for a long time, and the purposes of high electricity eliminating effect and high stability are achieved.
Further, the mixing temperature of the nascent state polyolefin powder and the antistatic compound is 50-60 ℃, and the standing time is 60-72 h.
Higher mixing temperature can destroy the surface appearance of nascent state polyolefin, influences the ability of adsorbing antistatic compound, and lower mixing temperature makes antistatic compound mobility worsen to influence antistatic compound's inflow pore, under suitable mixing temperature and the time of stewing, antistatic compound can get into inside the pore of nascent state polyolefin powder, thereby avoids in olefin polymerization process, and the too fast seepage of antistatic compound influences antistatic effect and stability.
The antistatic compounds comprise hydroxy esters having at least two free hydroxyl groups, alcohols and ketones containing up to 7 carbon atoms, polyepoxide oils, R-N (CH)2CH2OH2)2Alkyl diethanolamines of (1), amides of R-CONR 'R'.
Further, the hydroxy ester having at least two free hydroxy groups is glyceryl monostearate and glyceryl monopalmitate;
the polyepoxide oil is epoxidized soybean oil or epoxidized linseed oil, preferably the polyepoxide oil is a commercial product under the trademarks Edenol D82 and Edenol B316.
The R-N (CH)2CH2OH2)2Wherein R is an alkyl group containing 10 to 20 carbon atoms.
The amide of said R-CONR 'R ", wherein R, R' and R" may be the same or different and are each a saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms.
Further preferably, the antistatic compound is R-N (CH)2CH2OH2)2Wherein R is an alkyl group containing from 13 to 15 carbon atoms, as sold under the trademark Atmer163, or a natural alkyldiethanolamine, such as Armostat 410M.
Based on the weight of the nascent state polyolefin powder, the dosage of the antistatic compound is 0.1-10.0%, preferably 1.0-5.0%.
The amount of the nascent polyolefin powder loaded with the antistatic compound is 0.05 to 5.0 percent, preferably 0.1 to 1 percent, based on the weight of the polyolefin powder in the reactor.
The particle size selection range of the nascent polyolefin powder is 100-.
Further, the nascent state polyolefin powder is introduced into the bottom of a bubbling fluidized bed of the polymerization reactor, or the middle and the bottom of a descending section of a circulating fluidized bed of the polymerization reactor.
Olefin gas is used to introduce nascent state polyolefin powder loaded with antistatic compound into the polymerization reactor filled with polyolefin powder. The raw material gas is adopted for transmission, so that impurities can be prevented from being introduced, and the antistatic compound can well participate in the antistatic reaction in the olefin polymerization process.
In addition, the static electricity generated during the polymerization process can be monitored, and the antistatic compound-supporting nascent polyolefin powder can be intermittently added by cascade control when the static voltage rises, or can be continuously added, preferably the antistatic compound-supporting nascent polyolefin powder is intermittently added by cascade control when the static voltage rises.
The catalyst used in the polymerization process in the step (2) is a Ziegler-Natta catalyst or a metallocene catalyst.
The Ziegler-Natta catalyst comprises a magnesium halide, a titanium compound having at least one Ti-halogen bond, and an electron donor compound.
Further, the magnesium halide is MgCl2。
Further, the titanium compound is TiCl4、TiCl3Or Ti (OR)n-yXyThe above-mentioned Ti (OR)n-yXyWherein n is the valence of titanium, y is a number from 1 to n-1, X is a halogen and R is a hydrocarbon group having 1 to 10 carbon atoms.
The metallocene catalyst comprises at least one transition metal compound comprising at least one bond II, and at least one cocatalyst selected from an aluminoxane or a compound capable of forming an alkyl metallocene cation.
The olefins are CH ═ CHR α -olefins, where R is hydrogen or a hydrocarbyl group having 1 to 12 carbon atoms.
The olefin comprises ethylene, propylene, 1-butene, 1-hexene and 1-octene.
The olefins are polymerized either individually to form homopolymers or in combination with each other to produce copolymers.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, a large amount of antistatic compounds can be loaded in nascent polyolefin by loading the antistatic compounds on the nascent polyolefin, and then the nascent polyolefin powder loaded with the antistatic compounds is introduced into a polymerization reactor filled with polyolefin powder, so that the antistatic compounds can slowly seep out of the surface from the interior of the polyolefin to continuously generate an antistatic effect, thereby reducing the surface resistance, guiding positive and negative charges to freely flow and/or dissipate to gas, and further having lower electrostatic voltage on the surface.
Detailed Description
Comparative example 1
In comparative example 1, the polymerization was carried out in a bubbling fluidized bed of polyethylene using a metallocene catalyst system, the antistatic compound used being the commercial product sold under the trademark Atmer163 (formula R-N (CH)2CH2OH2)2Wherein R is an alkyl group containing from 13 to 15 carbon atoms), introducing an antistatic compound in the bottom of the bubbling fluidized bed by direct injection, in a proportion of 0.02% (200ppm) with respect to the mass of the polyethylene powder inside the bed.
Dissipation of the static electricity was observed by sampling and measuring the particle charge to mass ratio in a faraday cage after the antistatic compound was introduced into the reactor. The charge to mass ratio of the polyethylene particles at the sampling point of the bubbling fluidized bed after 5min of injection of the antistatic compound rapidly decreased from-3.65. mu.C/kg to 0.25. mu.C/kg and remained between 0.22. mu.C/kg and-0.24. mu.C/kg for a duration of 60min, indicating that the bubbling fluidized bed is at a lower static level. However, after 60min, the static started to rise gradually and returned to-2.34. mu.C/kg at 240 min.
The electrostatic data of the polyolefins in the fluidized bed detected during the polymerization are shown in Table 1.
Example 1
In example 1, the polymerization was carried out in a bubbling fluidized bed of polyethylene using a metallocene catalyst system, the antistatic compound used being the commercial product sold under the trademark Atmer163 (formula R-N (CH)2CH2OH2)2Wherein R is an alkyl group having 13 to 15 carbon atoms), a nascent polyethylene powder having a particle size in the range of 850-1000 μm and loaded with an antistatic compound at 60 ℃ was conveyed by means of pneumatic ethylene transport at the bottom of the bubbling fluidized bed and allowed to stand for 60 hours at the same mass ratio of the antistatic compound to the ethylene powder in the bed as in comparative example 1, which was 0.02% (200 ppm). Wherein the amount of the antistatic compound is 4.0% by weight of the nascent polyethylene powder for loading, and the amount of the nascent polyethylene powder for loading the antistatic compound is 0.5% by weight of the polyethylene powder in the bed.
After feeding the nascent polyethylene powder loaded with the antistatic compound into the reactor, dissipation of the static electricity was observed by sampling and measuring the particle charge to mass ratio in a faraday cage. The charge-to-mass ratio of the polyethylene particles at the sampling point of the bubbling fluidized bed after 5min of injection of the nascent polyethylene powder loaded with the antistatic compound is rapidly reduced from-3.60 mu C/kg to 0.25 mu C/kg, and can be maintained between 0.18 mu C/kg and-0.17 mu C/kg within the duration of 240 min. It is shown that the efficiency and stability of the transport of nascent polyethylene powder loaded with antistatic compound is better than the direct injection of antistatic compound under the given process compared to comparative example 1.
The electrostatic data of the polyolefins in the fluidized bed detected during the polymerization are shown in Table 1.
Comparative example 2
In comparative example 2, the polymerization was carried out in a circulating fluidized bed of polypropylene using a Ziegler-Natta catalyst system, the antistatic compound used being the commercial product sold under the trademark Atmer163 (of formula R-N (CH)2CH2OH2)2Wherein R is an alkyl group containing from 13 to 15 carbon atoms), introducing an antistatic compound in the middle of the descending section of the circulating fluidized bed by direct injection, in an amount of 0.025% by weight (250ppm) with respect to the weight of the polyethylene powder in the bed.
When the antistatic compound was fed into the reactor, dissipation of the static electricity was observed by sampling and measuring the particle charge to mass ratio in a faraday cage. The charge/mass ratio of the polypropylene particles at the sampling point of the circulating fluidized bed after 5min of injection of the antistatic compound was reduced from-4.47. mu.C/kg to 0.21. mu.C/kg and was maintained between 0.32. mu.C/kg and-0.11. mu.C/kg for a duration of 60min, indicating that the circulating fluidized bed was at a lower static level. However, after 90min, the static started to rise gradually and returned to-3.24. mu.C/kg at 240 min.
The electrostatic data of the polyolefins in the fluidized bed detected during the polymerization are shown in Table 1.
Example 2
In comparative example 2, the polymerization was carried out in a circulating fluidized bed of polypropylene using a Ziegler-Natta catalyst system, the antistatic compound used being the commercial product sold under the trademark Atmer163 (of formula R-N (CH)2CH2OH2)2Wherein R is an alkyl group having 13 to 15 carbon atoms), a nascent polypropylene powder having a particle size in the range of 850-1000 μm and loaded with an antistatic compound at 60 ℃ is conveyed in the middle of the descending section of the circulating fluidized bed by means of pneumatic conveying of propylene, and left for 72 hours, the amount of the antistatic compound used is 0.025% (250ppm) relative to the weight of the propylene powder in the bed, which is the same as that in comparative example 2. Wherein, the dosage of the antistatic compound is 2.5 percent relative to the weight of the nascent polypropylene powder for loading, and the adding amount of the nascent polypropylene powder for loading the antistatic compound is 1 percent relative to the weight of the polypropylene powder in the bed.
After feeding the nascent polypropylene powder loaded with antistatic compound into the reactor, dissipation of the static electricity was observed by sampling and measuring the particle charge to mass ratio in a faraday cage. After 5min of injection of the antistatic compound-loaded nascent polypropylene powder, the charge-to-mass ratio of polypropylene particles at the sampling point of the circulating fluidized bed is rapidly reduced from minus 5.04 mu C/kg to 0.28 mu C/kg, and the charge-to-mass ratio of the polypropylene particles can be maintained between 0.27 mu C/kg and minus 0.94 mu C/kg within the duration of 240 min. It is shown that the static electricity eliminating effect and stability of the nascent polypropylene powder carrying the antistatic compound are superior to those of the nascent polypropylene powder directly injected with the antistatic compound in the given process compared with the comparative example 2.
The electrostatic data of the polyolefins in the fluidized bed detected during the polymerization are shown in Table 1.
TABLE 1 static level
Figure BDA0003489561130000061
Figure BDA0003489561130000071

Claims (10)

1. A method for electrostatic control of an olefin polymerization process, comprising:
(1) mixing the nascent polyolefin powder with an antistatic compound at 30-60 ℃, and standing for 24-72h to obtain the nascent polyolefin powder loaded with the antistatic compound;
(2) when the electrostatic voltage is increased to the electrostatic voltage threshold value in the olefin polymerization process, introducing the nascent state polyolefin powder loaded with the antistatic compound into a polymerization reactor filled with polyolefin powder through cascade control so as to control the electrostatic voltage in the olefin polymerization process.
2. The method for controlling static electricity in the olefin polymerization process according to claim 1, wherein the mixing temperature of the nascent state polyolefin powder and the antistatic compound is 50-60 ℃, and the standing time is 60-72 h.
3. The method of claim 1, wherein the antistatic compound comprises at least two free hydroxyl groupsHydroxy esters of radicals, alcohols and ketones containing more than 7 carbon atoms, polyepoxide oils, R-N (CH)2CH2OH2)2Alkyl diethanolamines of (1), amides of R-CONR 'R'.
4. The method of claim 3, wherein the hydroxyl ester having at least two free hydroxyl groups is glycerol monostearate and glycerol monopalmitate;
the polyepoxide oil is epoxidized soybean oil or epoxidized linseed oil.
5. The method of claim 3, wherein the R-N (CH) is selected from the group consisting of2CH2OH2)2R in the alkyl diethanolamines of (a) is an alkyl group containing from 10 to 20 carbon atoms.
6. The method of claim 3, wherein R, R 'and R "in the amide of R-CONR' R" may be the same or different and are each a saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms.
7. The method of claim 1, wherein the antistatic compound is used in an amount of 0.1-10.0% by weight based on the nascent polyolefin powder.
8. The method of claim 1, wherein the antistatic compound-loaded nascent polyolefin powder is added in an amount of 0.05% to 5.0% based on the weight of the polyolefin powder in the reactor.
9. The method as claimed in claim 1, wherein the particle size of the nascent state polyolefin powder for loading the antistatic compound is 100-1200 μm.
10. The method of claim 1, wherein the antistatic compound-loaded nascent polyolefin powder is intermittently added by cascade control or continuously added by cascade control when the electrostatic voltage is raised to the electrostatic voltage threshold.
CN202210092023.4A 2022-01-26 2022-01-26 Electrostatic control method for olefin polymerization process Pending CN114409832A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1055742A (en) * 1990-04-11 1991-10-30 英国石油化学品有限公司 Gas phase olefin polymerization process
US20150087793A1 (en) * 2013-09-25 2015-03-26 Chevron Phillips Chemical Company Lp System and method for deterring fouling in a polymerization reactor
CN105452166A (en) * 2013-08-26 2016-03-30 巴塞尔聚烯烃意大利有限公司 Method for improving the operability of an olefin polymerization reactor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1055742A (en) * 1990-04-11 1991-10-30 英国石油化学品有限公司 Gas phase olefin polymerization process
CN105452166A (en) * 2013-08-26 2016-03-30 巴塞尔聚烯烃意大利有限公司 Method for improving the operability of an olefin polymerization reactor
US20150087793A1 (en) * 2013-09-25 2015-03-26 Chevron Phillips Chemical Company Lp System and method for deterring fouling in a polymerization reactor

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