Ziegler–Natta catalyst. A Ziegler–Natta catalyst , named after Karl Ziegler and Giulio Natta , is a catalyst used in the synthesis of polymers of 1-alkenes (α-olefins). Two broad classes of Ziegler– Natta catalysts are employed, distinguished by their solubility: Heterogeneous supported catalysts based on titanium compounds are used in polymerization reactions in combination with cocatalysts, organoaluminum compounds such as triethylaluminium , Al (C 2 H5 ) 3 . This class of catalyst dominates the industry. Homogeneous catalysts usually based on complexes of Ti, Zr or Hf. They are usually used in combination with a different organoaluminum cocatalyst, methylaluminoxane (or methylalumoxane, MAO). These catalysts traditionally include metallocenes but also feature multidentate oxygen- and nitrogen-based ligands. Ziegler–Natta catalysts are used to polymerize terminal 1- alkenes (ethylene and alkenes with the vinyl double bond): n CH 2 =CHR → −[CH 2 −CHR] n −
Posted on: Thu, 23 Oct 2014 07:52:18 +0000
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