Third generation superactive catalysts

Nonetheless, in order to set up a drastically simplified process it was indispensable to have a further improved catalyst system available. This objective was reached in the following years, when Himont (Himont has taken over Montedison s and Hercules activities in the polypropylene sector) and Mitsui P.C. developed the third generation superactive catalysts (cf. Sect. 6.7). The main characteristics of these catalysts can be summarized as follows ... 

Current Processes. The development of superactive third-generation supported catalysts enabled the introduction of simplified processes, without sections for catalyst deactivation or removal of atactic polymer. By eliminating the waste streams associated with the neutralization of catalyst residues and purification of the recycled diluent and alcohol, these processes minimize any potential environmental impact. Investment costs arc reduced by approximately one-third over slurry process plants. Energy consumption is minimized by elimination of the distillation of recycled diluent and alcohol. The total plant cost for the production of polymer is less than 130% of the monomer price, when a modem process is used, compared to 175% for a slurry process. 

The effectiveness of the third generation, superactive Ziegler-Natta catalyst is dependent on reproducible dispersion of the active sites on the support as well as the chemical and physical properties of the support itself. The five basic indispensable requirements for this superactive catalyst are ... 

Fig. 4. Activity vs polymerization time. Polymerization occurs in hexane at 343 K (70°C) and 0.7 MPa (7 bat) with a superactive third-generation catalyst...

MgCl2-Supported Catalysts. The scientific and patent literature reports several methods for the preparation of the MgCl2-supported catalysts of third and superactive third generations. They can be classified as follows ... 

---