| Abstract: | The surface composition of TiCl3-based Ziegler—Natta catalysts prepared by various methods was analyzed by ESCA to correlate the total amount of surface titanium with the catalyst activity in propylene polymerization. The ESCA peak ratio (Ti 2P3/2/Cl 2P) of the catalysts was measured to estimate the surface composition. The titanium index defined as the product of the (Ti/Cl peak ratio and surface area) was closely correlated with the catalyst activity in polymerization. This indicates that surface titanium concentration and surface area determine the catalyst activity. It was also found that removal of surface aluminum and chlorine at the catalyst preparation stage results in concentration of titanium at the surface and an increase in surface area. |
