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MgCl 2 is the most common Ziegler-Natta catalyst carrier, the catalyst prepared with a high polymerization activity, and the product has a good performance. The common anhydrous MgCl of 2 presents a regular α-MgCl 2 crystal form, the preparation of the catalyst before its activation treatment, so that it changes to have a large number of lattice defects δ-MgCl 2 crystal form, in order to facilitate TiCl 4 load. The recrystallization activation method is a relatively common MgCl 2 Activation Methods, researchers have a lot of work in the field. The main idea of ??the recrystallization activation method: First MgCl 2 soluble to the electron donor solvent subsequently removed through certain electron donor to MgCl 2 recrystallization obtained crystalline form confusing activated carrier. Has now been developed a more re-crystallization method, such as the solvent was evaporated, cooled and chloride precipitation, the existing reported articles and patents are also more concentrated in the use of these methods, while the use of polyhydroxy alcohols recrystallization MgCl 2 rarely reported. In this paper, a new type of MgCl 2 recrystallization activation method with double hydroxyl glycol as complexing precipitating agent recrystallization MgCl 2 after off alcohol treatment was activated the carrier, thereby preparing the Ziegler-Natta catalyst having a high activity. The method is simple, flexible control of the recrystallization process so as to adjust the performance of the catalyst. This method breaks home and abroad the MgCl 2 of patent protection on alcohol activation, the resulting catalyst performance has important significance to the development of Ziegler-Natta catalysts. Thesis the following aspects: (1) examine diol role and its impact on the performance of the catalyst during catalyst preparation; (2) examine the diol species and preparation conditions on the catalytic performance, optimize catalyst the preparation conditions; (3) the use of glycol recrystallization mM MgCl 2 of thinking, designed and prepared novel composite catalyst. Specific work and the results are as follows: 1. 1,4 - butanediol as a complexing precipitating agent recrystallization dissolved in tetrahydrofuran (THF) in the MgCl 2 , was prepared by a new structure MgCl 2 / THF / Bu (OH) 2 compounds. Dealcoholation treatment the compound of TEA obtained after the activation of the MgCl 2 vector the load of TiCl 4 obtained after the high activity of the Ziegler-Natta catalyst. 1,4 - butanediol, and found that 1,4 - butanediol can be substituted with strong complexation bishydroxy located mM MgCl 2 of THF in the catalyst preparation process, 2 and MgCl form cross-Contact aggregate structure, MgCl 2 recrystallization. Diol recrystallization activated Prepared conditions, mild, resulting carrier presents δ-MgCl 2 crystal form, has a large specific surface area (69.70 m 2 · g -1 ). Catalyst has higher Ti content (5.79 wt%), in the ethylene polymerization showed high polymerization activity (47.38 kgPE · (gTi) -1 · h -1 · atm -1 ), and the polymerization product having a broader molecular weight distribution (MWD = 9.02). Investigated glycol recrystallization activation Preparation mM MgCl 2 carrier and its load, the process of the catalyst, of the diol type, alcohol / Mg molar ratio, de-alcohol type of agent and the TiCl < sub> 4 factors such as amount of the crystalline form of the catalyst, specific surface area, particle diameter, Ti content, the polymerization activity and kinetic characteristics of the performance of such impact, to optimize the preparation conditions of the catalyst. The study found that, by selecting the appropriate diol and dealcoholating agents, changing the alcohol / Mg molar ratio of TiCl 4 added amount can be more precise regulation of the above catalyst characteristics. Diol is then crystallized activation of Preparation mM MgCl 2 load the optimum conditions of the Ziegler-Natta catalyst: Select 1,4 - butanediol as a recrystallization reagent, TEA dealcoholating agents, alcohol / Mg molar ratio of 1, the load when the Ti / Mg molar ratio is greater than 2:1. 3 using 1,4 - butanediol mM MgCl 2 recrystallization of SiO 2 The surface prepared MgCl 2 / Bu (OH) 2 / SiO 2 complexes of TEA-treated MgCl < / sub> / SiO 2 composite carrier, high activity Ziegler-Natta catalysts the load TiCl 4 . SiO 2 has a high specific surface area and good particle morphology, the study found, the the MgCl 2 recrystallization of its surface both improved the MgCl 2 The morphology of the carrier, but also retains the high activity of the characteristics of the carrier MgCl 2 supported catalyst. The catalyst prepared in this manner is larger than the surface area (311.20 m 2 · g -1 ), the Ti content is low (1.38 wt% of) the polymerization activity is very high (up to 94.44 bulk density than kgPE · (gTi) -1 · h -1 · atm -1 ), polymerization products MgCl 2 < / sub> catalyst increased. After 4. Using polystyrene, acrylic acid (PSA) recrystallization MgCl 2 , prepared MgCl 2 / PSA composite carrier the load TiCl 4 high activity Ziegler-Natta catalyst. The study found that the carboxyl group in the PSA also has a crosslinking effect, make re-dissolved in THF recrystallization MgCl 2 secondary recrystallized precipitate similar diols. The catalyst obtained by the method having a layered structure, the larger surface area (148.71 m 2 at · g -1 ) in the polymerization of ethylene, having a high polymerization activity (41.12 kgPE · (gTi) -1 · h -1 · atm -1 ), and is not sensitive to hydrogen. PSA added affected MgCl 2 center of activity of the catalyst carrier, wherein the low molecular weight part of the increase, the lower the molecular weight of the resulting product.
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