【摘要】 用静态循环反应装置考察了各种过渡金属离子交换的沸石催化剂上乙烯的聚合反应。发 现在PdY,NiY,RhY,RuY上乙烯能选择性地进行二聚,CoY的二聚活性较差,FeY没有活 性,而在CrY上则发生乙烯的高聚反应。不同沸石交换Ni后,NiY和NiX能选择性地催化乙 烯二聚反应,在同样条件下的活性页NiY>NiX,NiM的二聚活性较差,NiA没有活性,而Ni- ZSN-5则主要是催化乙烯的高聚反应。对NiX沸石,Ni₂₊离子交换度对催化乙烯二聚活性有 较大的影响。在低于100℃的反应温度下,只有当交换度大于36%时才呈现二聚活性,并且活 性随交换度的增加而增大,但交换度太高时活性反而下降。更多还原

【Abstract】 The polymerization of ethylene over various transition metal exchanged zeolites was studied by using a closed recirculation apparatus. For exchanged Y-zeolites, it is found that dimerization of ethylene to butenes proceeds selectively over PdY, NiY, RhY and RuY catalysts, but the activity of CoY is low and FeY shows no activity. While over CrY catalyst, high polymerization of ethylene occurs. For nickel exchanged zeolites, NiY and NiX catalysts promote the dimerization of ethylene selectively, and the activity of NiY is higher than that of NiX under the same conditions. The activity of NiM is low, and NiA shows no activity for dimerization. While Ni-ZSM-5 catalyst promotes mainly the high polymerization of ethylene. Furthermore, the activity of NiX strongly depends on the degree of Ni2+ ion exchange. At reaction temperature below 100℃, only the NiX catalysts with degree of Ni2+ ion exchange above 36% show activity for ethylene dimerization, and the activity increases with the increase of Ni2+ exchange, but as the degree of Ni2+ exchange exceeds 80%, the activity decreases notably. By comparing with homogeneous catalysis, it is concluded that the catalytic properties of transition-metal exchanged zeolites mainly depend on the nature of exchanged metals, meanwhile they are strongly affected by the stereoscopic structure and the acidity of zeolites and the location of metallic ions in zeolites.更多还原