Synthesis And Application Of Multi-site Phosphorus Ligands Based On Aminophenols

In recent years,Cr-based catalysts exhibit high catalytic activities and high selectivities in the selective ethylene oligomerization to produce linear α-olefins,which attracted extensive attention from both academia and industry.It was revealed by studies that the structure of ligand played decisive role in catalytic performance.Various types of ligands were developed by researchers,such as PNP,PNC=N,PC=N,PN-Cn-NP,PNN,NNO and NPN type.Design,synthesis of ligands with novel structure and the study of the relationship between the catalytic performance and the structure of catalyst become the key aspect in this field.Two main studies were included in this thesis,which are,(1)Three types of multi-site ligands,L1-L10,were synthesized by the reactions of diphenylphosphine chloride with aminophenols,aminocresol,and phenylenediamines,respectively.Structure of the ligands were confirmed by 1H NMR、13C NMR、31P NMR、UV、IR、MS and elemental analysis.(2)Cataytic systems were formed by combining the ligands with chromium salt and methylalumoxane(MAO),which were applied in catalyzing ethylene selective oligomerization.Effects of reaction conditions like solvent,temperature,Al/Cr molar ratio and pressure of ethylene on the catalytic performance were studied.The relationships between catalytic properties and methods for the formation of complexes,structure of ligands were studied by comparison.It was revealed the catalytic activity of 5.91×106g/(mol Cr·h)with 1-octene selectivity of 72.94% and the total selectivities of 1-hexene and 1-octene of 82.11% were obtained with L4/Cr(III)/MAO system at 50℃,2.5MPa of ethylene and Al/Cr molar ratio of 700.