PNSiP/Cr(III)/MMAO催化乙烯选择性齐聚连续化反应性能及其动力学研究

设计了乙烯选择性齐聚连续化反应装置，将硅胺基桥联双膦型配体铬配合物(PNSiP/CrCl₃(THF)₃)、改性甲基铝氧烷(MMAO)组成催化体系，考察了其催化乙烯选择性齐聚连续化反应性能，并对该反应动力学进行研究。结果表明：当反应温度为60 ℃、乙烯压力为5.0 MPa、氢气分压为0.2 MPa、连续化反应20 h时，该催化体系的催化活性可达46.13×106 g/(mol Cr·h)；产物中1-己烯和1-辛烯的总选择性最高达到88.52%，固体产物聚乙烯（PE）质量分数为0.09%。PNSiP/Cr(Ⅲ)/MMAO催化体系在乙烯选择性齐聚连续化反应中具有催化活性高、副产物(甲基环戊烷+亚甲基环戊烷)少、固体低聚物少、可实现长周期运行的优点。对PNSiP/Cr(Ⅲ)/MMAO催化乙烯选择性齐聚连续化反应动力学方程进行拟合计算，得到该反应对主催化剂浓度的反应级数为1.32、对乙烯压力的反应级数为1.92；当主催化剂摩尔浓度为7.09 μmol/L、反应温度为40～60 ℃、压力为5.0 MPa时，该反应的表观活化能为109.7 kJ/mol。

Study on the Reaction Performance and its Kinetics of Selective Continuous Ethylene Oligomerization Catalyzed by PNSiP/Cr(III)/MMAO

A reaction reactor for selective continuous ethylene oligomerization was designed, and the catalytic system consisting of PNSiP/ CrCl₃(THF)₃ precatalyst and modified methylaluminoxane (MMAO) was formed to investigate its catalytic performance for selective continuous ethylene oligomerization and also study the reaction kinetics. The results show that the catalytic activity of the system can reach 46.13×106 g/(mol Cr·h) when the reaction temperature is 60 ℃, the pressure of ethylene is 5.0 MPa, and the partial pressure of hydrogen is 0.2 MPa, and the reaction time for 20 h; the total selectivity of 1-hexene and 1-octene in the product reaches up to 88.52%, and the mass fraction of the solid oligomer (PE) is 0.09%. In fact, the catalytic system of PNSiP/Cr(Ⅲ)/MMAO has the advantages of high catalytic activity, few by-products (methylcyclopentane + methylenecyclopentane), few solid oligomers and long-term operation in the selective continuous ethylene oligomerization. After the fitting calculation of the kinetics equation for selective continuous ethylene oligomerization catalyzed by PNSiP/Cr(Ⅲ)/MMAO, it can be obtained that the order of the reaction to the main catalyst molar concentration is 1.32, and that to ethylene pressure is 1.92; the apparent activation energy of the reaction is 109.7 kJ/mol when the main catalyst molar concentration is 7.09 μmol/L, the reaction temperature is 40－60 ℃, and the pressure is 5.0 MPa.