Ziegler-Natta Catalyzed Polymerization of Polypropylene

Polypropylene grades manufactured using Ziegler-Natta catalysts are predominandy isotactic, with a comparatively broad molecular weight distribution Ziegler-Natta 

2 Manufacturing Polypropylene with Ziegler-Natta catalysts 

We have a choice of four major polymerization techniques by which to manufacture polypropylene using Ziegler-Natta catalysts slurry, liquid propylene, solution, and gas phase. Regardless of which technique is employed, all polymerization plants must accomplish the same basic goals they must 

In the slurry process, propylene monomer is dissolved in a hydrocarbon diluent in vhich the polymerization process occurs. The polymerization products are either soluble (the highly atactic components) or insoluble. Both the insoluble and soluble components are collected and form separate product streams. The insoluble species form a slurry in the solvent, from which they are removed by centrifugation. The soluble, atactic component is removed with the solvent as another product stream. To separate the atactic polymer from the solvent, the solution is heated allowing the solvent to flash off, leaving the atactic polymer behind. Any unreacted monomer is degassed from the solution and recycled to the start of the polymerization process. 

Another method of manufacturing polypropylene employs the liquid monomer as the polymerization solvent. This process, known as the liquid propylene or bulk-phase process, has a major advantage over the slurry method in that the concentration of the monomer is extremely high. The high concentration increases the rate of the reaction relative to that seen 

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