Improved catalytic performance of hierarchical ZSM-5 synthesized by desilication with surfactants

Hierarchical ZSM-5 zeolites were synthesized by alkaline desilication and a surfactant induced re-assembly. Contrary to the purely alkaline desilicated zeolites a strong increase in external surface area, a narrow pore size distribution of 3–10 nm and a decreased Brönsted acidity could be achieved when using CTAB as a surfactant throughout the alkaline treatment. The hierarchical pore system and the decreased acidity lead to an improved catalyst lifetime in the methanol to hydrocarbon conversion. A further improvement could be accomplished by increasing the surfactant concentration during the desilication re-assembly preparation. Tailoring of mesopore size and specific surface area was achieved using surfactants with different chain lengths.

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► Surfactant assisted desilication of ZSM-5.
► Hierarchical ZSM-5 with narrow mesopore size distribution.
► Improved catalytic lifetime in methanol conversion with hierarchical ZSM-5.