Bimetallic catalyst has been a hot research topic as it can realize one-pot synthesis of polyethylene with bimodal molecular weight distribution (MWD). The kinetics of ethylene homopolymerization with a novel Cr-iV bimetallic catalyst and corresponding monometallic S-2 and iV catalyst were studied at various experimental conditions. MWD deconvolution of polymers made by these catalysts showed interaction between Cr and V active centers in the Cr-iV bimetallic catalyst
reduced the activity of Cr centers
while activity of V centers was improved. Polymerization temperature almost did not change mass fractions of polymers produced by two active centers. The simplified single-center kinetic model for ethylene homopolymerization was employed to describe polymerization behaviors of Cr and V centers in Cr-iV bimetallic catalyst. Kinetic parameters of each active center were estimated by fitting experimental results of polymerization rates with model prediction. Compared to monometallic catalyst
Cr center in the Cr-iV catalyst had decreased chain propagation rate constant
which lead to reduction of polymerization activity
whereas V center in the Cr-iV catalyst had decreased chain deactivation rate constant