摘要
使用催化剂MgCl_2/C_4H_4(COOC_4H_9)_2/TiCl_4和混合烷基金属助催化剂MgBu_2/AlEt_2Cl在30—80℃,系统压力为1.04×10~5Pa(绝对)的条件下进行了丙烯聚合动力学研究。讨论了[Al]/[Ti]和[Mg]/[Al]对催化活性、聚合物的等规度以及分子量分布的影响。结果表明混合烷基金属助催化剂的浓度对聚合速度的影响仍可用Langmuir-Hinsbelwood机制来描绘。研究了温度与隹化活性和等规度的关系,表明超过50℃活性降低,接近50℃时等规度出现最大值。随着聚合温度的增加聚丙烯的分子量变小,尤其当温度高于60℃时这种变化更为明显。
The kinetics of propylene polymerization has been investigated with MgCl_2/C_6H_4(COOC_4H_9)_2/TiCl_4 as catalyst and alkyl metal mixture MgBu_2/AlEt_2Cl as cocatalyst under 1.04×10~5Pa of system pressure and at 30—80℃. The effect of alkyl metal molar concentration ratio, [Mg]/[Al], and [Al]/[Ti] on catalyst activity, the isotactic index and the molecular weight distribution of polypropylene were discussed. The increase in the activity of the catalyst system containing MgBu_2 was primarily due to the improvement in kinetic behaviour. The catalyst activity and the isotactic index of polymer obviously decreased when [Mg]/[Al] was less than 1/4. A decrease in [Mg]/[Al] led to a narrowing of polydispersity and increase in M_(?).The whole isotacticity decreased no matter whether [Mg]/[Ti] was greater or smaller than 40. The dependence of the polymerization rate on the concentration of alkyl metal can be described by the Langmuir-Hinshelwood mechanism. The study on the relationship between temperature, catalyst activity and isotacticity showed that activity lowered when temperature was above 50℃. A maximum value of isotacticity appeared on approaching 50℃. The molecular weight of polypropylene decreased with increasing polymerization temperature, and became eSpecially apparent at temperatures above 60℃.
出处
《石油化工》
CAS
CSCD
北大核心
1992年第6期377-382,共6页
Petrochemical Technology
