Research On Novel Ziegler-Natta Catalyst For Ethylene Slurry Polymerization

Polyolefin industry is an important sympol of a country's petrochemical industry. Catalyst is the key of polyolefin technology. It does have an extremely close relationship with the development of the performance of polyolefin. Ziegler-Natta catalyst is widely used in polyethylene industry due to its easy preparation and low sensitivity to impurity. Among all the catalysts used as polyolefin catalysts, Ziegler-Natta catalyst is the most widely used catalyst. However, the catalyst's activity is not high and with poor Copolymerization performance. It baffled industrial applications of the Ziegler-Natta catalyst. There are two approaches to modify supported Ziegler-Natta catalyst. One way is adding organic electronic compounds(Lewis alkali). Another way is to some organic groups through covalent bond connected to titanium, in order to directly or indirectly change activity center of nature.Based on previous studies, the main purpose of this paper is to modify supported Ziegler-Natta catalyst through the their reaction with phenol, 2,4-Di-tert-butylphenol and 2,6-Di-tert-butylphenol.etc. specific organic compounds, receive cat2,cat3 and cat4, in order to alter the nature of the catalyst's active sites. the catalyst systems were investigate by SEM, BET and XRD analysis, for determining catalyst element content, particles morphology, surface area, hole and catalyst internal structure, also investigated the effects of the temperature in polymerization, Al/Ti mole ratio, the amount of hydrogen, copolymerization of ethylene and 1-butylene and copolymerization of ethylene and 1-hexene's amount of comonomer were studied in a 0.5L and 2L polymerizer. Investigative results indicated that the modification of catalyst's content of Ti were lower than Cat1, which were 7.44%,7.59% and 7.81%; surface area were higher than Cat1, which were 194.8m~2/g, 234.5m~2/g and 326.6m~2/g, and have internal lacunaris. The best reaction temperature for catalysts were 80℃and the best molar ratio of Al/Ti for Cat were 300. The modification of catalyst is sensitive to hydrogen, the MI of PE could be effectively regulated by hydrogen. The copolymerization performance of Cat4 is best. The 1-hexene content of ethylene-1-hexene copolymer was 0.704%. The 1-butene content of ethylene-1-butene copolymer was 1.050%. We found that the 2,6-Di-tert-butylphenol improved the performance of catalyst greatly.