一种新型双亚胺吡啶铁系催化剂的乙烯低聚研究

线性α 烯烃广泛地应用于洗涤剂、增塑剂、润滑油等精细化学品的合成以及作为共单体制备线性低密度聚乙烯 (ＬＬＤＰＥ) .目前工业上主要是应用ＳＨＯＰ法1] 、Ｃｈｅｖｒｏｎ工艺和Ａｍｏｃｏ工艺2 ] 通过乙烯低聚制备 .近些年发展起来的新型高活性后过渡金属乙烯低聚催化剂能够高选择性地制备线性α 烯烃3 ,4] .Ｂｒｏｏｋｈａｒｔ等4] 的研究表明 ,对于双亚胺吡啶铁系乙烯聚合催化剂而言 ,配体上苯基的邻位取代基位阻减小可以实现乙烯低聚 ,并具有高活性、高选择性以及理想的低聚产物分布 .本文的工作是从配体的空间位阻效应对催化剂…

STUDY ON ETHYLENE OLIGOMERIZATION WITH A NEW DIIMINE PYRIDINE IRON-BASED CATALYST

A new iron based catalyst 2,6\|bis(1\|fluorenylimino)ethyl] pyridine iron dicloride (2) was synthesized via Shiff base condensation with 2,6\|diacetylpyridine and 9\|aminofluorene hydrochloride under formic acid as catalyst.Ethylene oligomerizations were carried out using this new catalyst and methylaluminoxane as cocatalyst under various conditions.The effects of Al/Fe molar ratio,reaction temperature and ethylene pressure on catalytic activity and product distribution were investigated.This novel catalyst had a good activity for ethylene oligomerization (e.g. 4 21×10 6g oligomers\5mol -1 Fe·h -1 ,Al/Fe molar ratio=2000,reaction temperature=40℃,ethylene pressure=1 5?MPa).The catalytic activity increased with the increasing concentration of MAO.The tendency to produce more C 4～C 10 olefins was attributed to the more chain transfer reactions to MAO.The higher the reaction temperature,the lower catalytic activity was present.The reasonable explanation was the combination of the accelerated catalyst's deactivation and the decrease in ethylene concentration in solvent due to the elevated temperature.Under such condition,however,the oligomerization of ethylene produced more short chain olefins which are adapted to act as comonomers for preparation of linear low density polyethylene materials.Ethylene pressure in autoclave also had an important influence on catalytic activity and carbon\|number distribution of product.The catalytic activity increased sharply with the elevated ethylene pressure.However,the proportion of C 4～C 10 olefins in product decreased in higher pressure due to the enhanced chain propagation reaction.The research work indicated that the control of catalytic activity and product distribution can be realized by the variation of oligomerization conditions such as Al/Fe molar ratio,reaction temperature and ethylene pressure.The results also showed that the ethylene oligomerization employing this novel iron\|based catalyst mainly produces the C 4～C 10 olefins with high selectivity for linear C 4～C 10 α \|olefin (>98%).