Effect of Modifiers on MgCl2-Supported Ziegler-Natta Catalyst

Polyolefins, including polyethylene and polypropylene, represent one of the most important families of plastic materials, indispensable in modern life. Achieving optimal properties for these materials is essential, and this depends heavily on advancements in catalyst support and polymerization technology. The production of high-performance catalysts plays a crucial role in improving polymer properties. Recent research has focused on using metal chlorides (Lewis acids) in Ziegler-Natta catalysts to enhance catalytic activity and polymer characteristics. This study introduces a novel precipitation method to prepare the MgCl2-based support and investigates the modification of the TiCl4/MgCl2/EtOH/Surfactant catalyst system with AlCl3, ZnCl2 and their combination. The results demonstrate that the combined use of AlCl3 and ZnCl2 significantly outperforms the individual modifiers, with the optimal AlCl3+ZnCl2 MgCl2 ratio of 14 yielding the highest activity (24-26 kg PE/g cat.). Differential scanning calorimetry (DSC) analysis revealed that the thermal properties, including melting temperature (135.7 degrees C) and crystallinity (56.5%), remain largely unaffected by the modification. Additionally, gel permeation chromatography (GPC) results showed a significant increase in molecular weight (42 x 104 g/mol) and polydispersity index (22.1). The modifications improved comonomer incorporation and enhanced key polymer properties, such as molecular weight distribution and bulk density, while maintaining comparable morphology to the unmodified system. These findings highlight the potential of tailored catalyst modifications for advancing polyolefin production.