Study On Synthesis Mechanism And Properties Of MgCl₂/Isooctanol/TiCl₄ Ethylene Polymerization Catalysts

The development of the polyolefin industry is one of the important signs of the development of a national petrochemical industry.The key to polyolefin technology lies in the catalyst.The improvement of polyolefin resin performance is closely related to the development of catalyst.Ziegler-Natta catalyst(Z-N catalyst)has been continuously improved and perfected since its inception.Because of its simple preparation process,low sensitivity to impurities,and low cost,it has been widely used in industrial production.In this paper we based on MgCl2/isooctanol/TiCl4 system polyethylene Ziegler-Natta catalyst,the carrier precursor MgCl2/isooctanol(MgCl2/2-EH)adduct with five different molar ratios of magnesium to magnesium was first prepared and analyzed.The properties of the adduct were determined to determine the optimum molar ratio of magnesium to magnesium for preparing the catalyst mother liquor.Then.three kinds of internal electron donor Ziegler-Natta polyethylene catalysts were prepared,and various aspects of the performance of the catalyst were tested and the preparation conditions were optimized.Then,through the analysis of the reaction process of the mother liquor in the preparation process of the catalyst,a series of conjectures on the preparation principle were proposed for the process.Finally,the polymerization conditions of the preferred catalyst were optimized,and the hydrogen blending and copolymerization properties were tested.The experimental results show that the carrier precursor MgCl2/2-EH prepared by molar ratio of magnesium to magnesium is the best.The original crystal structure of anhydrous MgCl2 is completely destroyed.The isooctyloxy group in isooctanol is embedded in Mg atom through O atom.A new adduct structure is formed between the Cl and the Cl atom.During the preparation of the catalyst mother liquor,the anhydrous MgCl2 particles are gradually consumed,and the formed precursor MgCl2/2-EH can form a stable colloidal system in the inert diluent n-decane.The contact between the catalyst mother liquor and the active component TiCl2 can be regarded as A phenomenon similar to "salting out" to re-precipitate solid catalyst particles during the titanium loading process.A polyethylene catalyst with internal electron donors as tetraethyl silicate(TEOS),ethyl acetate(EAC)and diethyl succinate(DIES)was prepared.The analysis results show that all three internal electron donors have improved catalysts.The role of morphology,in which TEOS catalyst has the highest activity.Under the polymerization conditions of temperature 85? and aluminum-titanium molar ratio of 200,the activity can reach 35 kgPE/gcat·h.The catalyst has good hydrogen sensitivity and 1-hexene copolymerization performance,which can reach the domestic leading level.