Metallocene Catalyst Systems and Control over the Propylene Polymerization

Abstract

While the metallocene catalysts were widely used to produce the metallocene polypropylenes (mPP) in other countries, the traditional Ziegler-Natta catalyst has still been dominantly employed for manufacturing the polypropylenes (PP) in our country at current time. The property of the mPP appears more improved than that of the PP produced by the Ziegler-Natta catalyst, and the market demand for the mPP is worldwidely increasing every year. Therefore, it is urgent to develop the metallocene catalysts for the industrial use in domestic companies. The metallocene catalysts are of versatile structures, which are able to show more exact control over the propylene polymerization activity and the polypropylene stereostructures than the Ziegler-Natta catalyst, and thus catalyze to generate new PPs of the diverse structures. This manuscript will give a detailed summary on the metallocene catalysts so far reported. The important factors such as temperature, propylene pressure, catalyst concentration, cocatalyst types and so on will be illustrated, which all have significant influence on the catalytic reaction activity. The reaction mechanism will be discussed as well.