一种新型双亚胺吡啶铁系催化剂的乙烯低聚研究

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%).

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 x 10(6) g oligomers.mol(-1) Fe.h(-1), Al/Fe molar ratio = 2000, reaction temperature = 40degreesC, ethylene pressure = 1.5 MPa). The catalytic activity increased with the increasing concentration of MAO. The tendency to produce more C-4 similar to 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 similar to 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 similar to C-10 olefins with high selectivity for linear C-4 similar to C-10 alpha-olefin (>98 %).