Study Of The Propylene Gas Phase Polymerization Ziegler-natta Catalyst System

Polypropylene is one of the most important species in general plastic, it is widely used in daily life. The polypropylene catalyst is absolutely necessary for the production of polypropylene, in the past 60 years, in addition to the first generation to the fifth generation of traditional Zigler-Natta catalyst, metallocene catalyst and late transition metal catalyst have been developed too. Because of various limiting factors,the fourth generation of Zigler-Natta catalyst is still widely used in industrial production of polypropylene. China needs lots of polypropylene catalyst each year,because there are several Unipol units of propylene gas phase polymerization in our country. But the property of domestic catalyst still lags behind the performance of imported catalyst, at the same time, there’s no domestic self-distinguishment catalyst which is suitable for Unipol gas phase polymerization unit. As a result of this truth, a large number of expensive polypropylene catalyst must be imported from abroad every year. Therefore, how to improve the property of domestic catalyst and develop self-distinguishment catalyst with independent intellectual property rights are the urgent issues to be solved. So, this paper has mainly carried out the following four works to solve these problems:(1)The preparation of Zigler-Natta catalyst: We use the method of one step with anhydrous magnesium chloride as the carrier, by changing the ratio of alcohol and magnesium, the amount of DIBP, the stirring speed, the heating rate and the composition of magnesium precursor, prepared 25 groups of different Zigler-Natta catalyst.(2)The evaluation of Ziegler-Natta catalyst: The shape and size of catalyst was determined by SEM. The content of titanium and ester in catalyst was determined by spectrophotometer and GC. The activity of catalyst was evaluated. The isotacticity ofpolypropylene was determined by heptane extraction method, then the bulk density of polypropylene was also determined. According to experimental data, the impact of different preparation conditions on the property of catalyst and polypropylene was analyzed.(3)The synthesis of external electronic donors: The active inhibitor of isopropyl myristate in the imported external electronic donor DA was synthesized by esterification method. Novel active inhibitor which name is EASTER-1 was synthesized by esterification method too. The purity and structure of the two compounds were analyzed by GC and NMR.(4)The evaluation and comparison of external electronic donors: DA and DB were evaluated by liquid phase polymerization method and high pressure slurry polymerization method. According to the polymerization activity, polypropylene isotacticity and polypropylene MFR, the impact of the two donors on polypropylene MFR, high temperature activity and hydrogen sensitivity were analyzed.