Effect of La and Ce on the catalytic performance of ZSM-۵ with the optimal Si/Al ratio in the HTO process

This study investigates, the performance of ZSM-۵ zeolite catalysts with different Si/Al ratios equal to ۴۰, ۱۲۰, and ۲۰۰ in the n-hexane catalytic cracking process in a fixed bed microreactor at ۵۵۰°C under atmospheric pressure with a WHSV = ۴ h-۱. To improve the acidity of the catalysts and increase the yield of light olefins, the best catalyst among the three synthesized catalysts was modified by lanthanum and cerium metals. These two rare earth metals were chosen as modifiers since they were expected to improve the acidic properties of the parent catalyst. Furthermore, XRD, FT-IR, FESEM, EDX Dot-Mapping, BET, and NH۳-TPD analyses were used to evaluate and characterize the synthesized catalysts. According to the results, the Z-La catalyst has significantly improved catalytic performance, such as the yield of light olefins, P/E ratio, and a decrease in the production of light alkanes and aromatic compounds compared to other catalysts. The yield of light olefins obtained from it was equal to ۶۲.۹۱%, and the P/E ratio was equal to ۳.۲۵. This significant progress in this catalyst compared to other catalysts in this research is due to adding La to H–ZSM-۵ zeolite, which causes changes and modifies the acidity properties of this catalyst (S/W ratio of acidity = ۰.۵۴).

Keywords:

Catalytic Cracking , ZSM-۵ Zeolite , Light Olefins , Lanthanum and cerium