Synthesis Of Zirconium And Hafnium Complexes With SNN-Tridental Coordination And Its Catalytic Study Of Olefin Polymerization

Polyolefin materials are a kind of polymer materials with large synthesis volume and wide range of applications,among which polyolefin elastomers are a class of high-end polyolefin materials with high performance.The synthesis method of polyolefin elastomer is mainly high-temperature solution polymerization method,and high-temperature catalysts are used in the polymerization process,so the preparation of new polyolefin elastomers with excellent performance needs to be designed and synthesized by designing and synthesizing a catalytic system with excellent thermal stability.This paper is mainly based on the study of the synthesis of zirconium and hafnium metal catalysts and the study of the catalytic properties of the catalyst by changing the polymerization conditions,in which the ligand structure of two different thiol substituents and their zirconium and hafnium metal catalysts were designed and prepared,and the ethylene homopolymerization reaction was carried out at 100°C using the complex 1-HfMe3 and the copolymerization reaction with ethylene with 1-octene was carried out by changing the polymerization temperature(130°C/150°C),the ligand structure and metal atoms.At the same time,the ligand structure and complex structure were analyzed by nuclear magnetic resonance spectrogram and X-ray single crystal diffraction.The important work content of this paper is introduced as follows:(1)Using 8-(R-mercaptan)-2-(2,6-diisopropylaniline)quinoline(1-2;1:R=ⁱPr;2:R=2,6-Me₂-C₆H₃)and MMe₄(M=Hf or Zr),can be prepared with high yield(79%-88%),zirconium,hafnium metal complexes 1-HfMe₃,2-HfMe₃,1-ZrMe₃ and 2-ZrMe₃.The four zirconium and hafnium metal complexes obtained were all structurally characterized by NMR resonance.Subsequently,the molecular structure of the complexes of 1-HfMe₃ and 1-ZrMe₃ was further confirmed by single crystal X-ray diffraction,in which the S atoms,N atoms,C atoms,and Zr/Hf metal center atoms formed a distorted octahedral shape.These four zirconium and hafnium metal catalysts were used for ethylene homopolymerization and copolymerization of ethylene with 1-octene to explore their catalytic activity.(2)In ethylene homopolymerization,the catalytic activity is regulated by changing the reaction pressure of ethylene polymerization at 100°C using 1-HfMe₃,and as the reaction pressure of ethylene(from 0.5 MPa to 4 MPa)increases,the polymerization activity of 1-HfMe₃ catalytic ethylene homopolymerization is increased by as much as40 times(from 6 kg(PE)·mol^-1(M)·h^-1 to 249 kg(PE)·mol^-1(M)·h^-1);when the reaction pressure of ethylene homopolymerization is kept unchanged(4 MPa),The catalytic activity of the hafnium catalyst is regulated by changing the amount of the impuritizer MAO,and with the increase of the amount of the impuritizer MAO(from 500equivalents to 5000 equivalents),the catalytic activity of the hafnium catalyst can be increased by up to seven times(from 249 kg(PE)·mol^-1(M)·h^-1 to 1539 kg(PE)·mol^-1(M)·h^-1).In olefin copolymerization,ethylene is copolymerized at 130°C and 150°C using ethylene as a monomer,and the 1-HfMe₃ catalyst has the highest activity(up to4290 kg(POE)·mol^-1(M)·h^-1).The catalytic activity of the metal catalyst is affected by the metal center and ligand structure.With[Ph₃C][B(C₆F₅)₄]as the co-catalyst,the catalytic activity of the metal catalyst is hafnium>zirconium at a polymerization temperature of 150°C;when the ligand structure is L1 or L2 and the metal central atom is hafnium metal,the 1-HfMe₃ catalyst has high activity and good high temperature resistance.