A Study Of Design Method Of Polypropylene Catalyst With Compounded Internal Electron Donor

A design method of polypropylene catalyst with compounded internal electron donors has been studyed. The main content includes three parts.The first part is the determination of the catalyst preparation process and the study of property of the internal electron donors. The factor of stirring rate, added temperature of internal electron donor and processing frequency of TiCl4has been researched. The optimum conditions were:A stirring rate of145rpm; Add temperature of internal electron donor at70℃; TiCl4treatment for two times. Select a variety of the experimental group developed diether and succinate compounds as internal electron doner, and using them synthesised catalyst component and examined the performance of them. The results showed that:a variety of1,4-diether as an electron donor effect is poor,1,3-diether and succinate good electron donor.The second part is the establishment of method. A content design method of polypropylene catalyst with compounded internal electron donor basing on many complex internal electron donor combinations has been studyed, and the design method has been constructed successfully. The method:Sketched complexing curves of two kinds of internal electron donors at first; then obtained each complex curve of internal electron donors; Finally, designed and fabricated complex internal electron donor catalyst basing on complex curves. This method was feasible to guide the preparation of the catalyst with any two kinds of internal electron donors.The third part is the validation of method. An application method about compounded internal donors was successfully raised, and a mixed catalyst of1,3-diethers and1,4-diethers was synthesized according to this method. Results showed that catalyst of good overall performance can be obtained when the ratio of1,3-diethers and1,4-diethers to the carrier input were0.71mmol·g-1and0.06mmol·g-1. Its activity of68kgPP·(gcat)-1, isotacticity of polypropylene of98.6%can both surpass the value of the catalyst component produced by using DIBP as electron donor; The catalyst had a good hydrogen adjustment sensitivity and the isotacticity of polypropylene is adjustable; Meanwhile, the carrier, catalyst and the polypropylene particles showed good spherical particles, which means the "copy" phenomenon is obvious, the activity. We also find, in this preparation system of catalyst, there was a "load saturation value" on the carrier when internal electron donors complexed with it. In the catalyst with only one internal electron donor,"load saturation value" being at inflection point of internal electron donor load curve; And in the catalyst with compounded internal electron donors, this saturation value was between the value of two internal electron donors. The catalyst would get a highest activity and good overall performance when load value of internal electron donors closed to the saturation value. Internal electron donors got a similar competitive complexing ability when they were structurally similar, by contrast, the ability was difference when structure quite different. It’s meaningful when two kinds of internal electron donor compounded with different structure, performance of the catalyst could be significantly modulated by minute adjusting the content of internal electron donors.