Post-synthetic improvement of H-ZSM-22 zeolites for the methanol-to-olefin conversion

作者：Dyballa Michael; Obenaus Utz; Rosenberger Melanie; Fischer Achim; Jakob Harald; Klemm Elias; Hunger Michael^*

来源：Microporous and Mesoporous Materials, 2016, 233: 26-30.

DOI：10.1016/j.micromeso.2016.06.044

• Zeolite ZSM-22
• Framework desilication
• Mesopores
• Bronsted acid sites
• Methanol-to-olefin conversion

Microporous ZSM-22 zeolites (structure type TON) were modified by treatments with different alkaline solutions for introducing mesopores. This surprisingly affected the nature and the density of both SiOH groups and Bronsted acid sites significantly, while the Bronsted acid strength was maintained. The catalyst lifetime in the methanol-to-olefin (MTO) conversion could be enhanced by a factor of up to 2 for an optimum Bronsted acid site density of 0.34 mmol/g, which was also accompanied by the highest propene selectivity of 48%. The product distributions of the parent microporous and the modified mesoporous ZSM-22 catalysts were very similar. This indicates that the shape selectivity of the modified ZSM-22 zeolites in the MTO conversion is mainly determined by the 10-ring pore system and not affected by introduced mesopores. Therefore, it can be excluded that catalysis near the pore mouths plays a significant role in the MTO conversion on ZSM-22 zeolites.

• 出版日期2016-10-1