摘要
采用PNP(双膦胺配体)/Cr(acac)3(乙酰丙酮铬)/MAO(甲基铝氧烷)催化剂体系进行乙烯选择性三聚/四聚的研究。向该体系内加入含有杂原子的小分子作为第二配体形成复合配体体系,可以改变催化剂性能。通过筛选发现,三苯基膦(PPh3)为第二配体可以提高1-己烯和1-辛烯的总选择性(从88.5%上升至91.8%),并可减少聚乙烯的含量。考察三苯基膦用量发现,当三苯基膦与Cr的物质的量之比为1∶1时,催化剂总选择性最好。
A catalytic system consisting of diphosphinoamine,chromium（Ⅲ）acetylacetonate and methylaluminoxane is a typical system for ethylene tri-/tetramerisation. Adding molecules with heteroatoms as a second ligand,such as amine,benzoate and triphenylphosphine into this catalytic system can form a mixed ligands system,which can lead to the change of performance of the catalytic system.Our studies demonstrate that,upon adding a second ligand into the system,the selectivity of 1-hexene increases while that of 1-octene decreases.Besides,the mass fraction of polymer and activity will also change.A catalytic system added with triphenylphosphine as the second ligand can achieve 47.2%selectivity of 1-hexene and 44.6% selectivity of 1-octene,which might be 43.4% and 45.1% without the second ligand.Among all the mixed ligands systems,the highest total selectivity of 1-hexene and 1-octene could be up to 91.8%,which was 88.5% without the second ligand.This process is companied with a activity decrease from 20 231 g/（g·h）to 12 975 g/（g·h）and a reduced polymer production.The dosage of PPh3 also shows remarkable effect on selectivity and activity of the catalyst when the mole ratio of PPh3 and Cr（acac）3 varies from 0 to 1.Adding more PPh3 beyond equivalent of Cr（acac）3 may not show stronger influence on the properties of the catalytic system.All the changes might be assigned to the coordination of heteroatoms to the metal center,which affects the coordination and insertion of ethylene.
作者
李博民
刘柏平
刘振
LI Bo-rain;LIU Bo-ping;LIU Zhen(School of Chemical Engineering,East China University of Science and Technology,Shanghai 200237,China)
出处
《华东理工大学学报（自然科学版）》
CAS
CSCD
北大核心
2018年第3期303-307,共5页
Journal of East China University of Science and Technology
关键词
PNP
乙烯四聚
复合配体
PNP
ethylene tetramerisation
mixed ligand
作者简介
李博民（1991-），男，硕士生，河南人，研究方向为乙烯选择性齐聚。;通信联系人：刘振，Email：liuzhen@ecust．edu．cn
