Mechanistic Study of Co2/Po Copolymerization Over Diethylzinc-Trihydric Glycerine Catalyst

Abstract

The copolymerization of carbon dioxide (CO2) and propylene oxide (PO) catalyzed by diethylzinc-trihydric glycerine catalyst is investigated through experimental and theoretical approaches. Experimental results show that the efficiency of catalyst is highly determined by the preparations, as the catalyst exhibits high activity when catalyst prepared by dropping glycerine into diethylzinc (ZnEt2). Conversely, the catalyst exhibits almost no activity. Theoretical calculation indicates that dropwise addition order could change the way ZnEt2 and glycerine reacted, which affects the structure of the catalyst and leads to activity variations. Simplified catalyst structure is constructed based on experimental and calculation results, which are employed in the subsequent study of the CO2/PO copolymerization. Further study shows that the catalyst is self-assembled and chain grew through a dimetallic-coordination-push mechanism. The calculation explains the effect of the molar ratio between the glycerine and the diethyl zinc on the activity, the deviation in the ratio will resulting in a reduction in the dimetallic structure leading to a reduction in activity.

Keywords: Keywords: CO2, Propylene oxide, Copolymerization, Mechanistic, Diethylzinc-trihydric glycerine catalyst