Study On Dynamic Behavior Of Propylene Polymerization By Several Ziegler-Natta Catalysts

ND Catalyst with 1,3-diol dibenzoate as internal donors on dynamic behavior of propylene polymerization were studied, and contrasting with three types of industrial applications' Ziegler-Natta catalyst with phthalate as internal donors. The effects of the polymerization temperature and the concentration of alkylaluminium and the concentration of external donor on catalyst activities , the stabilities of active centers , isotacticity and dynamic behavior of propylene polymerization was investigated. The results showed that the five types of catalysts have the similar dynamic behaviors at 10°-15°C, with the polymerization temperature increasing ,the time of the polymerization reaction speed reaching the biggest speed was shorten, polymerization catalyst activity increased linearly; the speed of the polymerization of N Catalyst is the smallest and the decay of catalyst activity is the most stable, the time of ND-02 Catalyst reaching maximum polymerization speed is the shortest, but the rate of the decay of catalyst activity is also the fastest; when Polymerization at 70℃-90℃, the higher the polymerization temperature, the average speed of polymerization is lower and the instability of the catalyst activity is poorer and the rate of decay of catalyst activity is sooner; when at low temperature, with the rise of temperature, the isotacticity of catalyst increase and the isotacticity of N catalyst is the best; when at higher temperature, with the polymerization raise, the isotacticity of catalyst drops, the isotacticity of ND-01 is the best; when the concentration of silicon hydride keep invariable, increasing of the concentration of alkylaluminium don't influence dynamic behavior of catalyst, but rate of the decay of catalyst activity, the isotacticity of catalyst decay; with Al/Ti increasing, ND-02 catalyst activity decay significantly ,when Al/Ti is lower, the isotacticity of ND-02 catalyst is the highest, when Al/Ti is high, the isotacticity of ND-02 catalyst decay rapidly; With the concentration of alkylaluminium increasing , the isotacticity of N catalyst change a little , when Al/Ti is high, the isotacticity of N catalyst is still high; When Al/Si is in constant and the concentration of alkylaluminum is lower, dynamic behavior of propylene polymerization and activity decay rapidly, but polymerization activities of CS-1 and 842 change a little.