Chemistry of MgCl(sub 2)-supported Ziegler-Natta catalysts studied by in situ infrared spectroscopy

摘要

The thesis relates to a study on the chemistry of the classical heterogeneous Ziegler-Natta catalyst system MgCl2/EB/TiCl4 - AlEt3/EB (Ethyl Benzoate) by in situ FTIR transmission spectroscopy. Reactions involved in preparation of, activation of, and polymerization with the catalyst have been studied. For this purpose, an in situ double-chamber liquid flow cell and technique were developed. The construction of the flow cell and the design of the system are based on liquid flow calculations in order to control liquid exchange through the solid particle layer in the IR-chamber and to obtain rapid flow-though in the cell. The construction also facilitates accurate positioning of the IR-cell. In situ polymerization of propene, involving only 3 mg catalyst (30 (mu)g Ti) and 0.14 mmol TEA, proves the inert conditions in the apparatus. The developed method is suited for reaction studies of liquid systems, solid/liquid systems, and system involving precipitation. In particular, the methods makes possible the detection of the carbonyl stretch vibration of liquid ester complexes at concentrations down to common polymerization conditions ((approx)3mM). Addition of EB during activation of the catalyst has been shown as a useful method to detect the liquid aluminium species in the liquid phase. The general applicability of the set-up should, in principle, make it suited for chemical solid/liquid systems other than Ziegler-Natta catalysts as well. 139 refs., 97 figs., 13 tabs.