茂金属/MAO催化剂催化1-癸烯齐聚动力学

Kinetics of Oligomerization of 1-Decene Catalyzed by Metallocene/MAO Catalyst

为有效控制合成润滑油基础油的性能,以tBuNC(Me)_2(η~5-C_5H_5)ZrCl_2/MAO催化剂催化1-癸烯齐聚,建立了排除扩散影响的动力学模型,考察温度和单体质量浓度对聚合速率的影响,以及温度对相对分子质量及其分布的影响。结果表明:聚合速率随着反应温度的升高而升高,计算得到表观活化能为4.86kJ/mol,聚合反应速率对单体质量浓度呈1.47级依赖;随着温度的升高产物分子质量减小,相对分子质量分布变宽,选择最佳聚合温度为80℃;产物相对分子质量分布接近2,符合茂金属催化剂作为单一活性中心的动力学模型假设。

1-Decene oligomerization is the most commonly used method for preparing poly-alpha-olefin （PAO）. PAO is currently the best synthetic lubricating base oil with low pour point, suitable viscosity with the change of temperature, excellent thermal stability, small evaporation loss and other advantages, which are especially suitable for alpine and frigid regions. Therefore, PAO is now widely used in automotive, aerospace and other industries. There are many catalysts for the oligomerization of 1-decene, among which the metallocene catalyst has good performance and the product has many advantages such as low viscosity and high viscosity index. Methyl aluminoxane （MAO） is commonly used as cocatalyst in metallocene catalysis. The polymerization kinetics are important for optimizing the catalyst system and reactor control. However, few studies on the kinetics of oligomerization of 1-decene catalyzed by metallocene/MAO have been reported at home and abroad. In order to control the performance of lubricant base oil effectively, the study of kinetics is necessary. In this paper, 1-decene polymerization was catalyzed by zBuNC（Me）2 （η5-C5H5 ） ZrCl2/MAO. The kinetic model of diffusion effect was established, and the effect of temperature and monomer concentration on the polymerization rate was investigated. The apparent activation energy was calculated as 4. 86 k j/mol. The polymerization rate was found to be dependent on the monomer concentration at 1. 47 level. The effects of temperature on the relative molecular mass and its distribution were investigated. As the temperature increased, the relative molecular mass of the product decreased and the relative molecular mass distribution became wider. The optimum polymerization temperature was found to be 80℃. Furthermore, relative molecular mass distribution was close to 2, which was consistent with the kinetic model hypothesis that the metallocene catalyst had a single active center. Combining kinetic results with polymer properties can provide for industry a method to control PAO performance.