The heptamethylbenzenium cation (heptaMB(+)) has been speculated to be one of the most important active intermediates involved in the "hydrocarbon pool" mechanism of methanol-to-olefin (MTO) conversion. By the use of DNL-6, a newly synthesized SAPO-type molecular sieve with large cavities, heptaMB(+) has for the first time been directly observed during methanol conversion under real working conditions. (13)C-labeling experiments suggested that olefin formation mediated by heptaMB(+) mainly follows the side-chain mechanism.

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