Supported rare earth catalysts were made from Nd（O-i-Pr）3 and the halides, especially chlorides of the ⅠA and ⅡA groups, used as catalyst supporters, for studying the relationship between the composition of supporters and the selectivity of supported rare earth catalysts. It was found that the electronegativity of the ⅠA or ⅡA elements showed an obvious effect on the selectivity of the supported catalysts, i.e. the selectivity of the supported catalyst was increased with the increase in their electronegativity, as in the case of supported Ti-catalyst .This rule was also held as the supporters are magnesium halides.
Catalytic characteristics of magnesium chloride supported rare earth catalyst system of Nd(OR) 3-n Cl n(n=0,1,2) in polymerization of butadiene was investigated.The result indicated that the ionic electronegativity of magnesium and content of chlorine as measured in mumber of atom are important factors that affect the catalytic characteristics.
Supported rare earth catalysts were made from Nd(O i Pr) 3 and the chlorides as well as bromides of the elements of ⅠA and ⅡA groups which were used as supporters of the catalyst. In the study on the relationship between the composition of supporters and the polymerization activity of butadiene in the presence of the supported rare earth catalysts, it was found that the electronegativity of ⅠA or ⅡA elements has an obvious effect on the activity of supported catalysts, that is the activity of the supported catalyst increases with the increasing of the electronegativity. This phenomenon is explained in terms of the interaction between the HOMO of the butadiene and the LUMO of the neodymium. This rule also holds in the case when halides of magnesium were used as supporters.
