Fourth generation controlled size/shape

The major advance offered by the later (fourth generation) supported catalysts is their controlled morphology, which rendered them suitable for all commercial polymerization processes. These are the only catalysts suitable for he full exploitation of the advantages of the solvent-less polymerization including the gas-phase process. These catalysts come in a variety of regular shapes, such as spherical, cubical, or cylindrical, as single particles or clusters of several particles, and are characterized by sufficiently narrow particle size distributions with the minimum of fines or coarse particles. 

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