【摘要】 考察了含碱金属离子和镍离子的X型沸石上乙烯的双聚反应。发现催化剂的活性有如下规律:LiNiX>NaNiX>KNiX。TPD考察表明催化剂的酸性亦有同样的规律。在LiNiX和NaNiX上乙烯的双聚反应出现诱导期,而在KNiX上则不出现。碱金属离子对镍离子有两方面的促进作用:一是调变催化剂的酸碱性,亦即调变活性中心Ni~+离子上的电子密度;二是调变活性中心Ni~+离子在沸石中的位置占据情况,亦即调变Ni~+离子的有效浓度。更多还原

【Abstract】 The dimerization of ethylene over X zeolites containing nickel ions and different alkali metal cations has been studied. It is found that the activities of the catalysts are in the following sequencet LiNiX>NaNiX>KNiX. TPD results show the same sequence for catalyst acidity. An induction period of ethylene dimerization appears on LiNiX and NaNiX, while on KNiX no induction period is observed. It is proposed that the alkali metal cations affect the active site Ni+ in two different ways; ( 1 ) to modify the acidity of the catalyst, i.e. to regulate the electron density of the active site Ni+; ( 2 ) to modify the location of Ni+ ions in zeolite cages, i.e. to adjust the effective concentration of Ni+ ions.更多还原