Stability Enhancement Of Zsm-5 Zeolite In Olefin Aromatization By Alkali Treatment: Comparison Of Medium

ZSM-5 zeolite samples with a SiO2/Al2O3 ratio of 40 were synthesized by a hydrothermal method, and treated by 0.3 M tetrapropyl ammonium hydroxide (TPAOH) and 0.3 M sodium hydroxide (NaOH) solution separately to create hollow structures. The synthesized ZSM-5 zeolite and treated ZSM-5 zeolite samples were evaluated for aromatization of 1-hexene in a continuous flow reactor. The prepared ZSM-5 zeolite samples were characterized by XRD, SEM, TEM, NMR, XPS, and other analyses. The results showed that the alkali treatment formed mesopores and hollow structures in the ZSM5 crystals without destroying the topological structure. The acid amount of ZSM-5 zeolite was also increased after alkali treatment. Compared with the ZSM-5 zeolite treated by TPAOH, the ZSM-5 zeolite treated by NaOH had more mesopores and a higher total acid amount but a lower strong acid amount, resulting in higher aromatics yields and catalytic stability for 1-hexene aromatization. The characterization of spent ZSM-5 zeolites suggested that the spent treated ZSM-5 zeolites contained less coke, leading to a smaller reduction of micropore surface area and volume than in the spent parent ZSM-5, which contributed to the stability enhancement.