This work presents an exhaustive mathematical model for the high pressure polymerization of ethylene in tubular reactors of configuration sim1lar to that encountered in the industry. Multiple injection of monomer, mixtures of initiators and chain transfer agents are considered together with realistic flux configurations. Typical heat transfer coefficients are estimated from industrial plant data. The effects of pressure pulse on the reactor behavior are also analyzed. Instantaneous temperature profiles produced by such pressure pulse were recovered from stationary simulations showing a very good agreement with the corresponding experimental data . The model features are demonstrated by predictions of temperature, concentrations of reactants and products and molecular properties as a function of reactor length. Also, appropriate predictive capabilities are d1sclosed by comparison of model simulation results and experimental data. The generation of a high temperature initiator, derived from oxygen, is assessed by comparison of temperature profiles corresponding to runs with and without oxygen.

We present a method for the adjustment of parameters in the mathematical modeling of industrial tubular reactors for high pressure polymerization of ethylene. We propose a reduced mathematical model for these reactors that aids in the task of model parameter update commonly done periodically in industrial plants. This reduced model was built from a detailed model for multiple peroxide and oxygen initiator systems we had developed before. Some of the assumptions in that rigorous model were reviewed in order to minimize computational effort. Good and faster predictions were obtained by assuming different constant jacket temperatures and pressures at each zone. Pressure pulse equations had to be included in the model. A simplification of the adjustment procedure is also proposed here. It consists in using only the reactions considered crucial for the description of this polymerization. The peroxide initiator and solvent mixtures were treated as fictitious unique initiator and solvent respectively. A procedure was established for the quick estimation of the kinetic parameters that represent initiator and solvent mixtures of different compositions. This resulted in a model that can be adjusted rapidly to predict the behavior of a specific industrial reactor. The reduced model was validated using experimental runs initiated by oxygen either alone or together with peroxide mixtures.

We study the process involved in metallocene activation and further propylene polymerization. In this paper, we begin by analyzing the behavior of soluble metallocene in propylene polymerization before advancing to the study of the heterogeneous polymerization. Experimental data obtained in a semibatch laboratory polymerization reactor using ethylenbisindenylzirconium dichloride (EtInd2ZrCl2)/ methylaluminoxane (MAO) are combined with a mathermatical model providing useful information such as number of active sites and their activation patterns. We present a mathematical model for the reactor that predicts not only reactor productivity but also the molecular properties of the product. We apply the model to soluble systems in order to find the optimal parameters for the catalyst itself and in the presence of different types of additives such as aluminum chloride (AlCl3) and ethyl benzoate (E.B.).