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Study on Silica and Silica-supported Metallocene Catalyst for Ethylene Polymerization

Author: YaoPeiHong
Tutor: WangXingYa
School: Northwest Normal University
Course: Polymer Chemistry and Physics
Keywords: Silicone Titanium-containing silica gel Metallocene Supported catalysts Polymerization of ethylene
CLC: O631.5
Type: PhD thesis
Year: 2009
Downloads: 213
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Abstract


The preparation process of the polyolefin catalyst carrier silica gel and titanium-containing silica gel, and prepared to meet the technical requirements of a polyolefin catalyst carrier silica gel and titanium-containing silica gel; investigated silica-based metallocene catalyst loading influencing factors, formed a metallocene catalyst loading. technology, the resulting catalyst polymerization performance and polymer properties to the technical requirements of industrial production. Sol - gel derived carrier silica gel, and their physical and chemical properties of the polyethylene catalyst the technical indicators carrier requirements, comprehensive screening and optimization of the preparation process involves various process conditions. The results show that the mother liquor nucleation temperature for 70 to 80 ℃, pH value of 9.0 to 9.5, time of 40 ~~ 50min, the mother liquor SiO 2 mass fraction of 3% to 5%; growth in the sol particles process control after adding SiO 2 and the mother liquor of SiO 2 molar ratio is 7 to 10, the pH value of 9.0 to 9.5, the sodium silicate addition rate to 150 ~ 250ml / h (waterglass density 1.11g/cm 3 ), and the reaction temperature is 80 to 90 ° C; aqueous sol gelation control pH 6.0 to 8.0 and a temperature of from 60 to 70 ° C; hydrogel stabilization aging time 6h, the pH value of about 9.0; drying silicone spray drying, before drying SiO 2 uniform conditions of the aquifer cake: Stir speed 600r/min, uniform time 40 ~ 50min, slurry solid content of 14% to 16%; the spray dryer turntable speed 12000r/min dryer inlet temperature of 300 to 320 ° C, the outlet temperature of 90 to 130 ° C. By sol - gel derived titanium mass fraction of 0.1% to 0.3% of the titanium-containing silica gel. Regulation and control of critical process conditions such as titanium source and the rate of hydrolysis of the silicon source. The results show that using inorganic titanium source Ti (SO 4 ) the 2 in (OC , and organic titanium source Ti 4 H 9 ) 4 can be prepared by qualified titanium-containing silica gel in the reaction system by adding a certain amount of H 2 O 2 and the hydrolysis of a titanium source generated when the large number of Ti (OH) 4 quickly its envelope formed by the merger of homeostasis, to ensure that the rate of hydrolysis of the titanium source and a silicon source match, and thus in all the reaction of the raw material titanium into the silica skeleton; H 2 O 2 , the amount of control the H 2 O 2 / titanium molar ratio greater than 5, the raw material of titanium The mass fraction of less than 0.3% is appropriate. This is because the raw materials by adding titanium fewer, the better the sake of entering the silica skeleton, the reaction temperature is 30 to 40 ° C. The experimentally obtained carrier silica gel and titanium-containing silica gel, and the load of the metallocene catalyst. The results show that in the catalyst loading process, the added effect of MAO Sec than added at once, the catalyst is dried prior to filtering and washing; the optimum parameters of the catalyst load: MAO / silica gel (ml / g) of 10:1, an Al quality Score 15% to 17%, mass fraction of 0.3% to 0.45% zirconium; prepared metallocene supported catalyst activity greater than 6200gPE/g.cat; particle size distribution of the resultant polyethylene products, molecular weight and its distribution, m.p. to achieve the requirements of the existing industrial production technology; homemade silicone for load Unipol gas-phase polyethylene process catalysts and polymerization studies, the performance of the technical requirements of the production of the existing plant; titanium-containing silica gel as a metallocene catalyst carrier found that the part of the fragmentation, the catalysts have low activity, the polymerization product morphology than homemade excluding titanium silica gel Poor, titanium-containing silica gel applied to the polyolefin the load for further study.

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CLC: > Mathematical sciences and chemical > Chemistry > Polymer chemistry ( polymer ) > Polymer physics and physical chemistry of polymers > Polymerization,polycondensation reaction
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