高性能淤浆法聚乙烯催化剂的研究

High Performance Catalyst for Slurry Polymerization of Ethylene

对一种新型高活性BCE-Ⅰ催化剂进行聚合评价,对BCE-Ⅰ催化剂及其制备的聚合物进行表征。与参考催化剂进行对比,考察了催化剂的粒径分布、催化活性、氢调敏感性和丁烯共聚等对聚合物的密度和堆密度等方面的影响。实验结果表明,在乙烯淤浆聚合工艺条件下(氢气分压0.28MPa、乙烯分压0.45MPa、温度80℃、时间2h),BCE-Ⅰ催化剂的活性较高(为50.9kg/g),BCE-Ⅰ催化剂制备的聚合物具有很大的堆密度(达到0.36g/cm3),明显高于参考催化剂制备的聚合物的堆密度(0.31g/cm3);BCE-Ⅰ催化剂制备的聚合物的粒径分布窄,细粉含量少,在高氢分压条件下(氢气分压0.68MPa、乙烯分压0.05MPa),140目以下细粉的质量分数约为12%,远低于参考催化剂制备的聚合物中140目以下细粉的含量(质量分数约为36%);同时BCE-Ⅰ催化剂的氢调敏感性和丁烯共聚性能均优于参考催化剂。

High performance polyethylene catalyst for slurry process was introduced and compared with a reference commercial catalyst. Particle size distributions, activities and sensitivities in response to hydrogen of the two catalysts as well as their product states were investigated. BCE - 1 catalyst possesses better particle size distribution and higher activity. Under polymerization conditions： hydrogen partial pressure 0.28 MPa, ethylene partial pressure 0.45 MPa, polymerization temperature 80 ℃ and time 2 h, activity of BCE - 1 catalyst can reach 50. 9 kg/g. As concerning ethylene polymers obtained by the two catalysts, the bulk density of polymer from BCE - 1 catalyst can be up to 0.36 g/cm^3, but from the reference catalyst only up to 0.31 g/cm^3. The particle size distribution of polymer from BCE - 1 catalyst is narrower and fine resin content less. Especially under high hydrogen partial pressure of 0.68 MPa （ ethylene partial pressure 0.05 MPa）, the fine resin content （ 〈 140 mesh） of the product in BCE - 1 case is in about 12% （mass fraction）, far less than 36% （mass fraction） in the reference case. The effects of catalyst properties mentioned above on copolymerization of ethylene and butylene and their relevant products were also investigated. BCE - 1 catalyst is more sensitive in response to hydrogen than its counterpart and exhibits better copolymerization performance. The bulk density of product copolymer from BCE - 1 catalyst is higher.