Boron alkyl as co-catalyst to improve polymerization yield and control polydispersity

This invention relates to a catalyst system using a boron alkyl in combination with an aluminum alkyl as a co-catalyst, a process for making the catalyst system and a process using the catalyst system for polymerization of olefins, especially alpha -olefins, such as propylene. While both boron alkyls and aluminum alkyls are known as co-catalysts separately, use of a boron alkyl with an aluminum alkyl as co-catalysts in olefin polymerization resulted in an unexpected increase in polymer yield. An increase in yield is accomplished without any increase in the amount of aluminum residue in the polymer product. The preferred boron alkyl is triethyl boron. The preferred aluminum alkyl is TEAl.