【摘要】 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,Pd²⁺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Pd²⁺离子的氧化还原性,二是调变Pd²⁺离子在沸石笼中的位置占据情况。更多还原

【Abstract】 The effect of the pre-evacuation temperature on the activity of LiPdY, NaPdY and KPdY for ethylenc dimerization has been investigated. It is found that along with the increase of evacuation temperature, the activity of these catalysts increases first and then decrcas s, and passes a maximum. The temperature for maximum activity and for deactivated evacuation is in the same sequence. LiPdY>NaPdY>KPdY. XPS results indicate that the reducibility of Pd2+ increases in the order of LiPdY<NaPdY<KPdY. An induction period of ethylene dimerization appears on LiPdY and NaPdY,while on KPdY and CaPdY no induction period is observed. It is suggested that the effect of alkali metal cations on Pd2+ ions is to regulate the location of Pd2+ in zeolite cages and the reducibility of Pd2+ ions.更多还原