两相体系内PNP/Cr(Ⅲ)/MAO催化乙烯齐聚

Ethylene oligomerization catalyzed by PNP/Cr(Ⅲ)/MAO in biphase systems

通过1-n-丁基-3-甲基咪唑六氟磷酸盐离子液体([BMIM][PF6])/环己烷构建了液/液两相体系。研究了两相体系内反应温度、Al/Cr摩尔比、离子液体浓度等因素对异丙基双膦胺配体(PNP)/Cr(Ⅲ)/甲基铝氧烷(MAO)催化乙烯齐聚性能的影响。研究结果表明:与均相催化体系相比,两相体系内PNP/Cr(Ⅲ)/MAO催化乙烯由四聚变为三聚,61-C=的选择性最高达到97.40%。齐聚产物存在于有机溶剂相,催化剂溶解在离子液体相,便于产物与催化剂的分离及催化剂的循环使用。

1-n-Butyl-3-methylimidazolium hexafluorophosphate （[BMIM] [PF6]）/cyclohexane biphasic system was used for studying performance of ethylene oligomerization catalyzed by diphosphinoamine ligand （PNP）/Cr（III）/ methylaluminoxane（MAO）. The effect of reaction temperature, molar ratio of A1/Cr and ionic liquid concentration on catalytic activity and product distribution was investigated. The results showed that compared with homogeneous catalysis system, the action of catalytic active center in biphase systems changed from ethylene tetramerization to ethylene trimerization. 1-℃ selectivity was up to 97.40%. The product existed in the organic solvent while the catalyst was dissolved in ionic liquids, which made the separation of product and recycle of catalyst easy.