Propylene polymerization with metallocene catalysts in industrial processes

Abstract

Product demands for polypropylene polymers cover a wide range of properties. Metallocene catalysts open up the way to influence the molecular properties of polypropylene by altering the ligand system of the metallocene complexes. This leads to new products with application properties which are not available with conventional catalysts. Concepts are presented to adapt metallocenes to modern, industrial polymerization processes. Some examples illustrate the particular advantages of this new generation of catalysts.

Reversibly Crosslinked Networks of Nanoparticles in Metallocene-Catalyzed Olefin Polymerization

“…One reason that their use in industrial applications is still limited is the necessity to immobilize the metallocenes. [3] Homogeneous olefin polymerization has several disadvantages, e. g., the need for large quantities of solvents, the lack of morphology control and the formation of fine powders that possess a low bulk density and are difficult to handle. [1,4] The requirements for catalyst immobilization can be summarized as follows: (i) The support must provide a 'framework' which holds the growing polyolefin together so that a high density product particle is produced; [5] (ii) this network must undergo fragmentation during the polymerization process [6,7] in order to make the active sites accessible for the monomer and give high catalyst productivities; (iii) the active sites should be evenly distributed throughout the catalyst; (iv) for industrial applications the support system should be cheap and readily available.…”

Donor Atom‐Stabilized Aluminum Alkyls as Cocatalysts for the Ziegler–Natta Polymerization of Propene

“…They are mainly produced by vanadium-based catalysts like VCl 4 and VOCl 3 in combination with diethylaluminum chloride as cocatalyst. [10] As aluminum compounds like triethylaluminum and diethylaluminum chloride are extremely sensitive to traces of air and moisture, they are quite difficult to handle and imply various risks, especially for industrial processes. Schumann et al synthesized a large variety of sulfur-, nitrogen-and oxygen-stabilized aluminum alkyls, thus providing a certain stability towards oxygen and moisture.…”

Functional Star‐Like Polystyrenes as Organic Supports of MeDIP(2,6‐iPrPh)2FeCl2 Catalyst Toward Ethylene Polymerization

“…Indeed, olefin polymerization on supported catalysts enables the production of polyolefin beads with a controlled morphology and generally avoids the formation of fine powders difficult to handle. [1][2][3] Up to now, Ziegler-Natta and metallocene catalysts have mainly been supported on specially treated and costly inorganic compounds such as silica, alumina, or magnesium chloride. [4][5][6][7] The polyolefins so formed always…”