The catalyst triethyl aluminium and titanium tetrachloride are an organoaluminium compounds. Triethyl aluminium is a dimer. So, it is mainly used as a co-catalyst in the industrial production of polyethylene and polypropylene. Triethyl aluminium and titanium tetrachloride is known as Zieglar-Natta catalyst and used in preparation of high dcnsity polythcnc. For cxample