两种铬系催化剂的制备及催化乙烯聚合性能研究

Preparation of Two Kinds of Chromium-based Catalysts and Their Catalytic Performance for the Polymerization of Ethylene

通过共浸渍法制备了Cr-V/SiO2、 Cr-V-Ni/SiO2催化剂,比较了两种催化剂孔结构和表观形貌的差异,考察了浸渍pH值和活化温度对催化剂聚合活性和产品结构性能的影响。结果表明:Cr-V-Ni/SiO2催化剂活性较Cr-V/SiO2提高22%,聚合产物分子量增大54%;浸渍液pH=7时,制得的Cr-V-Ni/SiO2催化剂活性最高,在45℃、 0.18 MPa的聚合反应条件下,其催化活性达到109 g PE·gCat^-1·h^-1,且产物分散系数(PDI)值达8.28;600℃活化时,Cr-V-Ni/SiO2催化剂聚合产物的分子量较500℃增大54%。

Cr-V/SiO2 and Cr-V-Ni/SiO2 catalysts were prepared by a co-impregnation method. The pore structure and apparent morphology of these two catalysts were compared, and the effects of impregnation pH and activation temperature on catalyst polymerization activity and product structure and performance were investigated. The results of polymerization test and characterization showed that the activity of Cr-V-Ni/SiO2 catalyst increased by 22%, and the molecular weight of the polymerization product increased by 54%.When the pH of the impregnated solution was 7, the Cr-V-Ni/SiO2 catalyst had the highest activity. Under the polymerization conditions of 45 ℃ and 0.18 MPa, the catalytic activity reached 109 g PE·gcat^-1·h^-1, and the molecular weight distribution of the product reached 8.28. When activated at 600 ℃, the molecular weight of the polymerization product of Cr-V-Ni/SiO2 catalyst increased by 54% compared with 500 ℃.