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为了探明在Ni(Ⅱ)/SiO_2-Al_2O_3催化剂上丙烯齐聚反应诱导期的成因及活性中心的本质,考察了反应过程中镍离子与丙烯分子的相互作用,发现反应诱导期随着催化剂预抽空温度的升高而缩短,也随着丙烯预处理及反应温度的升高而缩短.用ESR、XPS法跟踪考察发现,随着丙烯在催化剂上反应的进行,首先Ni(Ⅱ)被丙烯还原成Ni(Ⅰ)离子.之后,丙烯与Ni(Ⅰ)配位形成不饱和配位离子,形成齐聚反应表面活性中间体,并且在反应过程中,二、三聚产物也可与Ni(Ⅰ)离子配位,形成三、四聚反应面活性中间体.结果表明在Ni(Ⅱ)/SiO_2-Al_2O_3催化剂上Ni(Ⅰ)离子是丙烯齐聚反应的活性中心。
In order to find out the formation mechanism and the nature of the active site during the oligomerization of propylene over Ni (Ⅱ) / SiO_2-Al_2O_3 catalyst, the interaction between Ni 2+ and propylene was investigated. It was found that the reaction- With the increase of evacuation temperature and shortening, propylene pretreatment and reaction temperature also shortened.Using ESR, XPS method to track the study found that with the reaction of propylene on the catalyst, the first Ni (Ⅱ) is reduced by propylene Ni (Ⅰ) ion is formed, and then propylene and Ni (Ⅰ) coordinate to form unsaturated coordination ions to form oligomeric reactive surface active intermediates, and during the reaction, the di- and trimerized products can react with Ni (Ⅰ) ) To form three or four polyamine reactive surface active intermediates.The results show that Ni (Ⅰ) ion is the active center of oligomerization of propylene on Ni (Ⅱ) / SiO 2 -Al 2 O 3 catalyst.