Energy Distribution of Active Sites in Heterogeneous Ziegler-Natta Catalysts. Method of Study of Active Site Non-Uniformity

The new method of investigation of active site non-uniformity was developed. The method is based on mass-spectrometric study of temperature programmed desorption (TPD) products from the catalyst surface at initial stages of olefin polymerization (up to 10 – 15 monomer units in chain). The method allows to obtain the information concerning the energy non-uniformity of active sites in terms of a distribution of active sites over activation energy of active Mt-C bond thermal destruction. By the method, the initial stages of ethylene and deuteroethylene polymerization with Ti-supported catalysts of different structure were studied. It is shown that the view of energy distribution of active sites depends on catalyst structure. The values of activation energy of thermal destruction of Ti-C bonds in differing active sites were estimated and energy spectra of active sites for catalysts were obtained.