Novel bridged tetradentate fourth-subgroup metal complex, and preparation method and application thereof

Abstract

The invention provides a novel bridged tetradentate fourth-subgroup metal complex, and a preparation method and application thereof. The complex has a structure as shown in a formula a, has good temperature tolerance, can keep very high catalytic activity at 120 DEG C, and can be used as a main catalyst for catalyzing ethylene homopolymerization to obtain ultrahigh-molecular-weight polyethylene; the complex can catalyze a copolymerization reaction of ethylene with norbornene, 1-hexene and 1-octene and is high in activity, and a polymer product with a high co-monomer insertion rate is obtained;and the complex can catalyze propylene polymerization to obtain a polypropylene product with high isotacticity.

Description

technical field [0001] The invention belongs to the technical field of olefin polymerization catalysts, and in particular relates to a novel bridged tetradentate fourth subgroup metal complex and its preparation method and application. Background technique [0002] Polyolefin products have many advantages such as abundant raw materials, low price, convenient production and processing, and superior performance. They are the most popular resin materials at present. The polyolefin industry represents the development level of a country's petrochemical industry. An important part of the national defense strategy. Olefin polymerization catalyst determines the internal structure and morphology of polyolefin products. It is the core technology in the development of polyolefin industry. Its development generally goes through three stages: a). Ziegler-Natta catalyst, which is the earliest olefin polymerization catalyst , its appearance gave birth to the polyolefin industry, but this ...

AI Technical Summary

Problems solved by technology

Olefin polymerization catalyst determines the internal structure and morphology of polyolefin products. It is the core technology in the development of polyolefin industry. Its development generally goes through three stages: a). Ziegler-Natta catalyst, which is the earliest olefin polymerization catalyst , its appearance gave birth to the polyolefin industry, but this type of catalyst is heterogeneous, it is difficult to be fully activated by the co-catalyst, there are multiple active centers, the catalytic efficiency is very low, and the ash content in the product is very high, which increases the difficulty of post-processing ; b). Metallocene catalysts, such catalysts need to use a large amount of expensive cocatalysts (MAO or boron promoters) during use, and the active center is easily poisoned and deactivated, which limits its application in industrial production; c). Non-metallocene catalysts, this type of catalyst has a single active center, relatively high activity, and the central metal has strong tolerance to heteroatoms. It not only has the advantages of the previous two generations of catalysts, but also can catalyze a variety of homopolymerization and copolymerization reactions. Therefore, it has a very good application prospect

[0003] The technical background closest to the present invention is: Exxon-Mobil's patents for a series of Salen-type metal complexes (eg: WO2017058388A1), which can catalyze the homopolymerization of ethylene and the copolymerization of ethylene and various α-olefins reaction, the activity is very high, and the product quality is also good, but the temperature resistance of this type of catalyst is generally poor, and the activity is very low under high temperature polymerization conditions, or even directly deactivated, and the industrial application is limited; the series of bridged four catalysts applied by Symyx company Patents for oxygen-type metal complexes (eg: US2004010103A1; WO03091262A1) and patents for a series of bridged tetraoxo-type metal complexes applied by Dow (eg: US20120108770A1; WO2013090396A1). These catalysts have excellent catalytic performance and high temperature resistance It can be called a classic among non-metallocene catalysts, but the synthesis process of this type of catalyst is very cumbersome and the synthesis cost is very high, especially in the selective protection and deprotection of hydroxyl groups, and the extensive use of noble metals for catalytic coupling.

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