负载型非茂金属催化剂结构的表征

Characterization of a Supported Non-Metallocene Catalyst

通过X射线衍射、红外光谱、扫描电子显微镜和电子探针显微分析方法对负载型非茂金属催化剂二苯甲酰甲烷基-环戊二烯基-二氯化钛(CpT i(dbm)C l2)、氯化镁载体和氯化镁-高岭土双载体的结构进行表征,对负载前后催化剂对乙烯聚合催化行为的变化给予解释。实验结果表明,CpT i(dbm)C l2在载体上分散得很好,从而避免均相催化剂在溶液中的双分子失活,是负载后催化活性得以提高的原因之一。负载后CpTi(dbm)C l2的化学结构未被破坏;双载体经过甲基铝氧烷(MAO)预处理后,MAO与双载体中的M gC l2.nTHF和硅羟基作用产生一种新的结构;CpTi(dbm)C l2与载体之间有一定的相互作用。由于双载体的表面不均匀,导致采用双载体负载型催化剂得到的聚合物的相对分子质量分布变宽。

Structures of supported non - metallocene catalyst dibenzoylmethyl - cyclopentadienyl - titanium dichloride （ CpTi （ dbm ） Cl2 ）, MgCl2 support and MgCl2- Kaolin bi - support were characterized by means of XRD,IR, SEM and EPM to investigate their different catalytic behavior in ethylene polymerization before and after being supported. Crystal structure of MgCl2·nTHF in bi - support was destroyed due to loading of CpTi （dbm）Cl2. CpTi （dbm）Cl2 was fully dispersed on supports, so that bi -molecular deactivation was avoided, which might occur when homogeneous catalyst was used. This was one of the reasons for improvement of catalyst activity. Chemical structure of CpTi （ dbm ） Cl2 kept unchanged after being supported. When bi - support was pretreated with MAt, interactions between methylaluminoxane, MgCl2·nTHF and silicon hydroxyl in bisupport led to a new structure. Some interactions existed between CpTi （dbm）Cl2 and supports. Surface of bisupport was not uniform, which led to broader relative molecular mass distribution of polymer obtained on bisupported catalyst.