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考察了催化剂预抽空温度对LiPdY、NaPdY和KPdY乙烯双聚活性的影响。发现这些催化剂的活性都随预抽空温度的升高先增大后减小,出现一极大值,并且活性里现极大值的抽空温度和丧失活性的抽空温度都按LiPdY、NaPdY、KPdY的顺序降低。XPS的结果证明从LiPdY到KPdY,Pd~(2+)离子的可还原性增加。在LiPdY和NaPdY上乙烯的双聚反应出现诱导期,而在KPdY和caPdY上则不出现。认为碱金属离子对钯离子有两方面的促进作用:一是调变Pd~(2+)离子的氧化还原性,二是调变Pd~(2+)离子在沸石笼中的位置占据情况。
The effects of pre-evacuation temperature on the polymerization of LiPdY, NaPdY and KPdY were investigated. It was found that the activity of these catalysts first increased and then decreased with the increase of pre-evacuation temperature, and a maximum appeared, and both the evacuation temperature and inactivation evacuation temperature of maxima in activity were decreased in the order of LiPdY, NaPdY and KPdY . The results of XPS demonstrate that the reducibility of Pd 2+ ions increases from LiPdY to KPdY. Induction of ethylene dimerization over LiPdY and NaPdY did not appear on KPdY and caPdY. It is believed that alkali metal ions promote palladium ion in two ways: one is to modify the redox activity of Pd ~ (2+) ions; the other is to adjust the position occupied by Pd ~ (2+) ions in the zeolite cage.