Synthesis of Amido-Quinoline-Based Hafnium and Zirconium Complexes and Their Catalytic Properties for Ethylene/1-Octene Copolymerization

TL;DR

This paper reports the synthesis of new hafnium and zirconium complexes that efficiently produce polyolefin elastomers with high 1-octene incorporation.

Contribution

The study introduces novel amido-quinoline-based Hf and Zr complexes with high thermal stability and catalytic performance for ethylene/1-octene copolymerization.

Findings

The Hf-1 complex achieved a copolymerization activity of 8.3 × 10⁶ g polymer/(mol catalyst · h) and 26 wt% comonomer incorporation.

Ligand electron-donating effects significantly enhance catalytic performance and comonomer incorporation.

Steric effects of ligand substituents have minimal impact on polymerization activity and molecular weight.

Abstract

The development of polyolefin catalysts plays a pivotal role in driving advancements within the polyolefin industry. In this study, five ligands (L1–L5) and six Hf (Hf 1-5) and Zr (Zr-1) metal complexes with amido-quinoline-based ligands were successfully synthesized by a simple and efficient synthetic route. The new Hf (Hf 1-5) and Zr (Zr-1) complexes exhibit high thermal stability, moderate activity, and excellent 1-octene incorporation capability. As a result, they have been successfully utilized in high-temperature solution-phase polymerization to produce polyolefin elastomers (POEs). The electron-donating effect of the ligand was identified as a crucial factor contributing to the improved catalytic performance and comonomer incorporation capability. The steric effects of substituents on the ligand have little impact on the olefin copolymerization activity, molecular weight, and comonomer incorporation capability. The Hf-1 complex demonstrates outstanding copolymerization activity and comonomer incorporation (8.3 × 106 g polymer/(mol catalyst · h), 26 wt%), offering significant potential for large-scale operations and practical applications.

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