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 (alpha-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(C₂H₅)₃. This class of catalyst dominates the industry.^[1]
• Homogeneous catalysts usually based on complexes of the group 4 metals titanium, zirconium or hafnium. They are usually used in combination with a different organoaluminum cocatalyst, methylaluminoxane (or methylalumoxane, MAO). These catalysts traditionally contain metallocenes but also feature multidentate oxygen- and nitrogen-based ligands.^[2]

Ziegler–Natta catalysts are used to polymerize terminal alkenes (ethylene and alkenes with the vinyl double bond):

n CH₂=CHR → −[CH₂−CHR]_n−;