Catalysts for Polypropylene

The first MgCL,-supported catalyst for polypropylene, was developed by Montedison in cooperation with Mitsui Petrochemical. In 1978 it was carried over to an already existing plant for the polymerization in a slurry. Thus, in comparison to the preexisting situation (Fig. 48), it was possible to achieve the first step toward eli-... 

The high yield catalysts for polypropylene, which have recently been developed by Montedison in cooperation with Mitsui Petrochemical though showing cristallite sizes similar to those of 6-TiClj, have activities even higher than two orders of magnitude. However, this does not translate into a substantial broadening of MWD as compared with traditional catalysts. In fact the degree of polymer poly-dispersity depends mainly on the chemical composition of the catalyst and, in some cases, it is actually lower than that obtained with TiClj—AKCjHs) (Table 3). 

Furthermore the development, during the 1970 s, of high yield catalysts for polypropylene made it possible to achieve also a better control of polymer stereoregularity. All this was the result of a careful choice, case by case, of an appropriate combination among carrier, transition metal compound, metal alkyl and possible third component. 

A slight narrowing of the integral polymer MWD was also observed with some "high yield catalysts for polypropylene, with increasing temperature (Q went from about 7.5 to about 6.0, going from 60 to 80 °C). 

Chadwick, J. G. Effects of Electron Donors in Super High Activity Catalysts for Polypropylene. In Ziegler Catalysts-, Fink, G., Miilhaupt, R., Brintzinger, H.-H., Eds. Springer Berlin, 1995 p 427. 

Albizzati, E. Galimberti, M. Giannini, U. Morini, G. The chemistry of magnesium chloride supported catalysts for polypropylene. Makromol. Chem., Macromol. Symp. 1991, 48/49, 223-238. 

The further development of the catalysts used for polypropylene synthesis had far-reaching consequences for process development. Due to the development of new processes based on the possibilities offered by the new catalysts and the changing range of properties of polymers, the development of catalysts for polypropylene synthesis will be briefly described ... 

Particles of catalysts for polypropylene, and the corresponding polypropylene particles can be examined using a scaiming electron microscopy to show that the polymer particle is about 20 times as big as the original catalyst. Porous... 

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