Abstract
The major goal of this research is to study the characteristics of the catalysts and polymerization process by experiments and simulations. In order to justify the value and usage of simulation tools in the catalyst design and process simulation of metallocene catalysts, this study also propose a new computational model that focuses on this point. The first part of this research is to design the structure of metallocene catalyst by computational chemistry. Semi-empirical molecular orbital method PM3 (MNDO parametric method 3) was used for metallocene catalyst modeling owing its computational efficiency and accuracy. This study has made a comparison of geometry and energy computational results between PM3 and higher order methods (ab initio, density functional theory) to evaluate the accuracy of PM3 method in the calculation of metallocene catalysts. After validating the computational method, PM3 method was employed to design the ZrCp[HB(PZ)3]Cl2 polymerization catalyst. Computational results have shown that the reaction process and characteristics of ZrCp[HB(PZ)3]Cl2 were identical to those of Cp2ZrCl2, thus confirms the ethylene polymerization capability of ZrCp[HB(PZ)3]Cl2 catalyst. The second part of this study is to propose a novel ethylene polymerization kinetic model for metallocene catalyst system and justify with experiments. The proposed G parameter for ethylene polymerization kinetic model has proved that it can solve the problem of the variation of polymer molecular weight and the non-ideal molecular weight distribution during the polymerization reaction, which was unable to represent precisely by conventional polymerization kinetic model. The final part of this study is the experimental and modeling study of the cyclic olefin copolymer by metallocene catalyst system. This model can calculate the polymerization conditions and is capable to predict the relation between the structure and physical properties of copolymer. The major contribution of this model is to calculate the yields, molecular weight, contents, and glass transition temperature of polymer at different temperatures, pressures, catalyst concentrations, and cocatalyst ratios. Consequently, the polymer properties can be modified by controling the polymerization conditions. Results show that by employing appropriate mathematical model and simulation tools, which can justify the accuracy of the experimental results and accelerate the development efforts. This may also save time and the resources for designing the catalyst and developing process for metallocene catalyst system.