CN-117209632-B - Preparation method of nickel catalyst for olefin polymerization

Abstract

The invention discloses a preparation method of a nickel catalyst for olefin polymerization, which comprises (1) reacting acenaphthoquinone, a water scavenger and substituted aniline in a first solvent under the action of the catalyst, cooling, filtering, concentrating and crystallizing to obtain a diimine ligand, and (2) reacting the diimine ligand with nickel salt in a second solvent, concentrating, crystallizing, filtering and washing after the reaction is finished to obtain the nickel catalyst. The method effectively solves the problems of poor selectivity, low yield, complex post-treatment and the like in the preparation process of the nickel-based catalyst, and has the advantages of short process flow, high yield, simple post-treatment and the like.

Inventors

• ZHOU KAIJING
• ZHUANG YANJUN
• YE LIFENG
• LI HONGFENG
• WANG ZONGLING
• ZHAO YUN
• TAO CHENGYU

Assignees

• 浙江巨化技术中心有限公司

Dates

Publication Date

20260508

Application Date

20230921

Claims (4)

1. 1. A method for preparing a nickel-based catalyst for olefin polymerization, comprising the steps of: (1) Under the action of a catalyst, acenaphthoquinone, a water scavenger and substituted aniline react in a first solvent, wherein the water scavenger is at least one of molecular sieve, trimethyl orthoacetate and acetal, the substituted aniline is at least one of 2-di (p-chlorophenyl) methyl-4, 6-dimethylaniline, 3,4, 5-trimethylaniline and 2-naphthylamine, the molar ratio of the acenaphthoquinone to the substituted aniline to the catalyst is 1:1.5-2.5:0.1-10, the mass ratio of the acenaphthoquinone to the water scavenger is 1:0.5-2.0, the dosage of the first solvent is 5-70 times that of the acenaphthoquinone, the reaction temperature is 20-150 ℃, the reaction time is 5-20 h, and after the reaction is finished, cooling, filtering, concentrating and crystallizing to obtain a diimine ligand; (2) And (3) reacting the diimine ligand with nickel salt in a second solvent, wherein the molar ratio of the diimine ligand to the nickel salt is 1:0.9-1.3, the second solvent is 5-40 times of the mass of the diimine ligand, the reaction temperature is 20-60 ℃, the reaction time is 4-24 hours, and after the reaction is finished, concentrating, crystallizing, filtering and washing to obtain the nickel catalyst.
2. 2. The method for preparing a nickel catalyst for olefin polymerization according to claim 1, wherein the catalyst is at least one of formic acid, acetic acid, p-toluenesulfonic acid and zinc chloride.
3. 3. The method for preparing a nickel catalyst for olefin polymerization according to claim 1, wherein the first solvent and the second solvent are at least one of dichloromethane, dichloroethane, methanol, ethanol, diethylene glycol dimethyl ether.
4. 4. The method for preparing a nickel catalyst for olefin polymerization according to claim 1, wherein the nickel salt is at least one of nickel bromide, nickel chloride, ethylene glycol dimethyl ether nickel bromide, diethanol dimethyl ether nickel chloride, diethylene glycol dimethyl ether nickel bromide.

Description

Preparation method of nickel catalyst for olefin polymerization Technical Field The invention relates to the technical field of catalysts, in particular to a preparation method of a nickel catalyst for olefin polymerization. Background With the development of research and application of olefin resin materials, the olefin resin materials gradually become necessary materials for daily life and industrial and agricultural production of people, and meanwhile, the olefin resin materials become indispensable important materials in the fields of advanced science and technology, national defense construction and the like. The Polyethylene (PE) material has the characteristics of good chemical resistance, low price, simple preparation, low density, good mechanical property and the like. Currently, polyolefin elastomers are mainly obtained by metallocene-catalyzed copolymerization of ethylene with α -olefins. However, the metallocene catalyst has the defects of difficult synthesis, low yield, large cocatalyst consumption, high cost and the like. The nickel catalyst, especially the diimine nickel complex catalyst, can be used for preparing polyethylene with high branching degree and large molecular weight from ethylene, especially the asymmetric nickel imine complex catalyst has high catalytic activity and moderate branching degree of polymer, and the branching ratio of different lengths can be regulated, thus having important application in the aspect of preparing polyethylene elastomer. This work is considered as a major milestone for post-transition metal catalyzed ethylene polymerization research, and the prepared polyethylene elastomer product can cover part of commercial POE thermoplastic elastomer products, can replace the commercial POE thermoplastic elastomer products to prepare adhesive films for packaging photovoltaic modules, and has great commercial application value. The key point of the preparation of the nickel-series olefin polymerization catalyst is the synthesis of ligand diimine, and the synthesis of imine by taking weak acid as a catalyst is the most classical method. The early Brookhart group was to synthesize N-aryl alpha-diimine ligands by this method. For structures with smaller steric hindrance, better yield can be obtained by using acid as a catalyst. For example, in 2011, the Yuan Jianchao group synthesized chloro-substituted tetra-substituted-N-aromatic ring- α -diimine ligand with formic acid as catalyst, the yield was 88-92% (J.Organomet. Chem.2011,696, 3251), in 2013, the Yuan Jianchao group synthesized highly active ortho-phenyl substituted acenaphthylenyl skeleton α -diimine ligand with yield of 62-67% (J.mol. Catalyst. A chem.2013,370, 132), in 2014, chenle group synthesized a class of large conjugated skeleton diimine ligand with acetic acid as catalyst, the ligand yield was about 70% (Dalton Trans.,2014,43,2900), in 2019, li Yougui group synthesized para-aryl substituted α -diimine ligand with formic acid as catalyst, and the yield was about 70% (CN 109762027A). And for the ligand with larger structural steric hindrance, the yield is lower, for example, in 2015, sun Wenhua, the task is combined into a series of asymmetric alpha-diimine nickel complexes containing bis (4-fluorophenyl) methyl substituted acenaphthylene skeleton, the ligand yield is 35-39% (Dalton Trans.,2015,44,12282), in 2015, gao Menglong, the task is combined into symmetric alpha-diimine ligand by taking formic acid as a catalyst, the steric hindrance is larger, the yield is only 7-13% (CN 104628596A), in 2022, sun Wenhua, the task is combined into campyl substituted alpha-diimine nickel complexes, the ligand yield is 11-38%, and the yield is reduced with the increase of substituent steric hindrance (Appl Oranomet chem.2022,36,6606). Starting from ketone and amine compounds, imine compounds can be synthesized by condensation reaction and removal of one molecule of water, and the reaction is reversible reaction, which is a main reason for low synthesis yield of diimine ligands, particularly diimine containing large steric hindrance substituent groups. The amine containing large substituent has large steric hindrance, the reaction is unfavorable to forward direction, and the diimine containing large steric hindrance substituent is unstable, and the generated water and diimine can be carried out in the reverse reaction direction, so that the reaction yield is low. Meanwhile, the prior art has the defects of more process steps, low post-treatment efficiency and the like. For example, IR106828B discloses a preparation process of homogeneous alpha-diimine nickel catalyst with different ligands for ethylene polymerization, and the invention provides a novel method for synthesizing symmetrical alpha-diimine nickel catalyst with acenaphthene and 2, 6-diisopropylaniline structure skeletons, and an ethylene polymerization process with high activity and acceptability. Wherein, the synthesis of the asymmetric complex is prepar