The effect of different process parameters on the TiCl4/internal donor/MgCl2/AlEt3 catalytic system using external donor and cyclohexylchloride

In this work, the effects of different process parameters were investigated on the performance of TiCl4/internal donor/MgCl2/AlEt3 catalytic system and produced polyethylene in a semi-batch stirred reactor. Various methods such as Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscope (SEM), sieve shaker and melt flow index (MFI) measurement were used to investigate the catalyst activity and final polyethylene product. The results showed that cyclohexylchloride as promotor, in the presence of external donor, increased the catalyst activity up to 110% at optimum ratio to titanium. On the other hand, the polymer particle size and fine particles, which were directly related to the catalyst activity in the most cases, increased up to 15% in the presence of optimal halocarbon/Ti ratio and decreased up to 45% using hydrogen in the studied range. Also, in the optimal ratio, cyclohexylchloride increased the active site concentration and as a result, the MFI increased significantly. Also at low agitator speeds, due to low heat and mass transfer, the catalyst particles were severely fragmented and the particle size was decreased clearly. The results also showed that due to the special catalyst structure, pre-polymerization with propylene increased the catalyst activity by approximately two times compared to ethylene pre-polymerization.