Effect of dealcoholation of support in MgCl2-supported Ziegler-Natta catalysts on catalyst activity and polypropylene powder morphology

摘要

Spherical support was produced using melt quenching method. Scanning electron microscopy (SEM) images showed that support particles have a rough surface morphology with small pore sizes. The size of primary particles determined to be about 50 nm. Produced particles were dealcoholated using hot nitrogen flow. In this study, the dealcoholation apparatus was similar to a fluidized bed reactor. It consists of three main zones: heating zone, bed zone, and expansion zone. This apparatus is capable to dealcoholate and elutriate support particles at the same time. Results showed a significant increase in specific pore volume and surface area of support particles during the dealcoholation. According to the obtained results, two mechanisms were proposed to explain effect of the dealcoholation on the morphology of support particles. Three dealcoholated samples of different alcohol contents were used in the catalyst preparation. Results showed that by decrease in alcohol content of support particles, specific surface area, and pore volume of catalysts increased. Moreover, titanium content of final catalysts increased slightly. Polymerization of propylene was carried out using obtained catalysts in slurry phase. An increase in catalyst activity and enhancement of polypropylene powder morphology were observed as the alcohol content of support particles decreased.