Thanyathon Niyomthai, Bunjerd Jongsomjit and Piyasan Praserthdam
Chulalongkorn University, Thailand
Posters & Accepted Abstracts: Chem Sci J
Ethylene homopolymerization by two types of Ziegler-Natta catalysts including none-THF and none-EtOH catalysts was compared. The influences of hydrogen concentrations on surface active sites of these catalysts were investigated based on catalytic activity. From the results, the EDX analysis and surface area measurement confirmed that none-EtOH catalyst had better active center distribution than that of none-THF. Thus, the none-EtOH catalyst could retard the hydrogen effect on surface active sites and show higher activity with increased hydrogen pressures1. However, catalytic activity was lower with high hydrogen pressure. In addition, to study for more detail about the hydrogen effect, none-THFs were modified with different metal halide additives (AlCl3 and FeCl2). Lewis acid modification can improve activity because it can remove the remaining THF in the final catalyst, which can poison the catalyst active sites via the ring-opening of THF2 which was confirmed by FT-IR and XRD measurements. Moreover, the activity enhancement was due to the formation of acidic sites by modifying the catalysts with Lewis acids. Thus, FeCl2 doped catalyst (Fe-THF) exhibited the highest activity followed by AlCl3 doped catalyst (Al-THF) and undoped catalyst (ZN-THF). In the H2/ C2H4 molar ratio of 0.08, Fe-THF showed a better hydrogen response on the surface active sites than Al-THF due to more titanium clustered distribution. Fe-THF is considered to have more clustered Ti species than Al-THF3. As a consequence, it led to obtain more possible chances to proceed chain transfer reaction by hydrogen.
Thanyathon studies the doctoral degree of chemical engineering at chulalongkorn university and joined catalysis and catalytic reaction engineering research group with the Royal Golden Jubilee program of Thailand Research Fund (TRF).