CN-122011245-A - Method and system for preparing high-viscosity poly alpha-olefin

CN122011245ACN 122011245 ACN122011245 ACN 122011245ACN-122011245-A

Abstract

The invention relates to the technical field of poly-alpha-olefin preparation, and discloses a method and a system for preparing high-viscosity poly-alpha-olefin. The method comprises the steps of S1, premixing a metallocene catalyst solution and an initiator in a premixing tank to obtain a premix, S2, carrying out a first polymerization reaction on the premix, a cocatalyst, alpha-olefin and a circulating material in a first polymerization reaction kettle to obtain an intermediate product, S3, after the intermediate product sequentially passes through a circulating pump and an online viscosimeter, part of the intermediate product circulates to the first polymerization reaction kettle, the other part of the intermediate product enters a second polymerization reaction kettle to carry out a second polymerization reaction, and controlling the circulation ratio of the intermediate product circulated to the first polymerization reaction kettle according to a viscosity value obtained by the online viscosimeter. The metallocene catalyst and the initiator form an alkylation intermediate first, and then the alkylation intermediate and the cocatalyst construct a cation active center, so that the generation of inactive species and the early inactivation of the active center are effectively avoided, and the catalytic efficiency is improved.

Inventors

SHI JIANXIN
LI YAN
ZHANG ANGUI
BAI ZHONGXIANG
XIE SHUFANG
CHEN JIHUA
ZHANG GENGMING
WANG FU
LI RUILONG
LIANG XUEMEI
HE JINXUE
AN LIANGCHENG
YUAN HUA
JIANG YAO
FAN NANA

Assignees

国家能源集团宁夏煤业有限责任公司
国家能源集团宁夏煤业有限责任公司煤炭化学工业技术研究院

Dates

Publication Date: 20260512
Application Date: 20260212

Claims (10)

1. A process for preparing a high viscosity polyalphaolefin comprising the steps of: s1, premixing a metallocene catalyst solution and an initiator in a premixing tank (4) to obtain a premix; S2, carrying out a first polymerization reaction on the premix, the cocatalyst, the alpha-olefin and the recycle material in a first polymerization reaction kettle (6) to obtain an intermediate product; S3, after the intermediate products sequentially pass through a circulating pump (7) and an online viscometer (16), part of the intermediate products circulate to a first polymerization reaction kettle (6), and the other part of the intermediate products enter a second polymerization reaction kettle (8) to carry out a second polymerization reaction; wherein the circulation ratio of the intermediate product circulated to the first polymerization reaction kettle (6) is controlled according to the viscosity value obtained by the online viscometer (16).
2. The method of claim 1, wherein the temperature of the premixing is 0-25 ℃, and/or, The metallocene catalyst solution is fed into the premix tank (4) by means of a metallocene catalyst feed pump (2), and/or, The initiator is fed into the premix tank (4) by an initiator feed pump (3).
3. The method according to claim 1 or 2, characterized in that the premix is injected into the first polymerization vessel (6) through a loop nozzle (5); Preferably, the loop nozzle (5) is located below the liquid level in the first polymerization vessel (6).
4. The method according to claim 1 or 2, characterized in that a cocatalyst solution is fed by a cocatalyst feed pump (1) via a cocatalyst feed line into the first polymerization reactor (6); preferably, one end of the cocatalyst feeding pipeline is connected with the cocatalyst feeding pump (1), and the other end of the cocatalyst feeding pipeline extends to below the liquid level of the first polymerization reaction kettle (6).
5. The process according to claim 1 or 2, characterized in that the α -olefin is fed into the first polymerization vessel (6) via an olefin feed line.
6. The method according to claim 5, wherein an olefin flow meter (11) and an olefin regulating valve (12) are sequentially arranged on the olefin feeding pipe along the olefin feeding direction, and the feeding flow rates of the metallocene catalyst, the cocatalyst and the initiator are controlled according to signals fed back by the olefin flow meter (11).
7. A process according to claim 1 or 2, wherein the circulation ratio is 50-80%, and/or, And when the viscosity value obtained by the online viscometer (16) is higher than the preset value, the circulation ratio is adjusted.
8. The method according to claim 1 or 2, wherein the metallocene catalyst comprises at least one of a zirconocene compound, a hafnocene compound, and a titanocene compound, and/or, The cocatalyst comprises at least one of N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, trityl tetrakis (pentafluorophenyl) borate and triphenylboron, and/or, The initiator comprises at least one of triethylaluminum, triisobutylaluminum, methylaluminoxane and modified methylaluminoxane, and/or, The alpha-olefins include C8-C14 alpha-olefins.
9. A system for preparing high-viscosity poly-alpha-olefin, which is characterized by comprising an olefin feeding pipeline, a cocatalyst feeding pump (1), a metallocene catalyst feeding pump (2), an initiator feeding pump (3), a premixing tank (4), a first polymerization reaction kettle (6), a circulating pump (7), an intermediate material pipeline and a second polymerization reaction kettle (8); The metallocene catalyst feed pump (2) and the initiator feed pump (3) are respectively connected with the premixing tank (4); the olefin feeding pipeline, the cocatalyst feeding pump (1) and the premixing tank (4) are respectively connected with the first polymerization reaction kettle (6); the outlet of the first polymerization reaction kettle (6) is connected with the inlet of the circulating pump (7), and the outlet of the circulating pump (7) is connected with the inlet of the intermediate material pipeline; the outlet of the intermediate material pipeline is respectively connected with the circulating material inlet of the first polymerization reaction kettle (6) and the inlet of the second polymerization reaction kettle (8); An on-line viscometer (16) is arranged on the intermediate material pipeline.
10. The system according to claim 9, further comprising an intermediate product flow meter (18) and an intermediate product regulating valve (19) arranged between the outlet of the intermediate material conduit and the second polymerization vessel (8).

Description

Method and system for preparing high-viscosity poly alpha-olefin Technical Field The invention relates to the technical field of poly-alpha-olefin preparation, in particular to a method and a system for preparing high-viscosity poly-alpha-olefin. Background Poly alpha-olefin (PAO) is widely applied synthetic lubricating oil base oil, has good thermal stability, oxidation stability and low-temperature performance, is widely applied to the fields of automobile engine oil, industrial lubricating oil and the like, and is the synthetic base oil with the widest application field, the most comprehensive performance and moderate price at present. Current PAO synthetic oil products are classified into low viscosity oils, medium viscosity oils and high viscosity oils according to their viscosity. Wherein, mPAO (metallocene poly alpha-olefin) refers to high-performance synthetic lubricating oil base oil polymerized by catalyzing alpha-olefin with a metallocene catalyst. In the process of synthesizing poly alpha-olefin (PAO), the metallocene catalyst brings great technical challenges to industrial production due to the ultra-high catalytic activity (usually only ppm-level dosage) and the high viscosity characteristic of a reaction system. Wherein, the polymerization degree (molecular chain length) is used as a core control parameter to directly determine the key performance indexes such as the viscosity, the pour point, the molecular weight distribution and the like of the product. Therefore, in the industrial continuous production process, how to realize the precise control of the micro catalyst to fully exert the catalytic activity of the micro catalyst and precisely regulate and control the polymerization degree, so that the preparation of the high-viscosity mPAO product with less catalyst residue, low ash content, high purity and excellent high-low temperature performance is a technical problem to be broken through at present. Disclosure of Invention The invention aims to solve the problems of over-wide molecular weight distribution, high catalyst residue and the like of poly-alpha-olefin in the prior art, and provides a method and a system for preparing high-viscosity poly-alpha-olefin. In order to achieve the above object, the present invention provides in one aspect a method for preparing a high viscosity poly- α -olefin, the method comprising the steps of: s1, premixing a metallocene catalyst solution and an initiator in a premixing tank to obtain a premix; s2, carrying out a first polymerization reaction on the premix, the cocatalyst, the alpha-olefin and the recycle material in a first polymerization reaction kettle to obtain an intermediate product; s3, after the intermediate products sequentially pass through a circulating pump and an online viscometer, part of the intermediate products circulate to a first polymerization reaction kettle, and the other part of the intermediate products enter a second polymerization reaction kettle to carry out a second polymerization reaction; and controlling the circulation ratio of the intermediate product circulated to the first polymerization reaction kettle according to the viscosity value obtained by the online viscometer. Preferably, the temperature of the pre-mixing is 0-25 ℃, and/or, The metallocene catalyst solution is fed into the premix tank by a metallocene catalyst feed pump, and/or, The initiator is delivered to the premix tank by an initiator feed pump. Preferably, the premix is injected into the first polymerization reactor through a loop nozzle; preferably, the loop nozzle is located below the liquid level in the first polymerization reactor. Preferably, the cocatalyst solution is fed into the first polymerization reactor by a cocatalyst feed pump via a cocatalyst feed line; Preferably, one end of the cocatalyst feeding pipeline is connected with the cocatalyst feeding pump, and the other end of the cocatalyst feeding pipeline extends to below the liquid level of the first polymerization reaction kettle. Preferably, the alpha-olefin is fed to the first polymerization reactor via an olefin feed line. Preferably, along the feeding direction of the olefin, an olefin flowmeter and an olefin regulating valve are sequentially arranged on the olefin feeding pipeline, and the feeding flow rates of the metallocene catalyst, the cocatalyst and the initiator are controlled according to signals fed back by the olefin flowmeter. Preferably, the circulation ratio is 50-80%, and/or, And when the viscosity value obtained by the online viscometer is higher than the preset value, the circulation ratio is adjusted. Preferably, the metallocene catalyst comprises at least one of a zirconocene compound, a hafnocene compound, and a titanocene compound, and/or, The cocatalyst comprises at least one of N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, trityl tetrakis (pentafluorophenyl) borate and triphenylboron, and/or, The initiator comprises at least one of triethylal