Modeling Of Gas Phase Polymerization Of Butadiene With Heterogeneous Catalyst

A model of gas phase polymerization of butadiene based on a multilayer model and an improved intrinsic kinetics model, considering the initial concentration distribution of active sites and the particle size distribution of catalyst, was proposed. The effects of reaction temperature, the particle size distribution of catalyst and the initial concentration distribution of active sites on the average molecular weight, the molecular weight distribution, and the particle size distribution of polymer were simulated. The experimental results and the simulation show a good agreement.The results show that the mean catalyst particle size has an effect on the average molecular weight and molecular weight distribution of polymer to a certain extent. The effect of the dispersing degree of catalyst particle size on the average molecular weight and molecular weight distribution of polymer is insignificant. With the mean catalyst size increasing, the molecular weight of polymer decreases and the molecular weight distribution of polymer broadens. With the increasing of reaction temperature, the average molecular weight is decreased and dispersing index of molecular weight is increased. But the differences between 40癈 with 50癈 is slight.The results of simulation of particle size distribution of polymer shows that there is not a replication of particle size distribution from catalyst to the polymer. With the increasing of reaction temperature, the polymer particle size distribution becomes narrower and the mean polymer particle size becomes smaller.The simulation results also indicate that the more uniformly the active compounds of catalyst are loaded on different particles, the bigger the average molecular weight of polymer, and the narrower the molecular weight distribution of polymer and the polymer particle size distribution.The proposed model can be used to predict the molecular weight, the molecular weight distribution and polymer particle size distribution of gas phase polymerization of butadiene. The method of modeling also can be referenced in modeling of gas phase polymerization of olefins.