Influence of seeding on FAU–∗BEA interzeolite conversions

The interzeolite conversion method is popularly employed for preparing zeolites. Here, FAU–∗BEA interzeolite conversions were performed in the presence of seed crystals under various synthesis conditions, that is, with and without organic structure-directing agents (OSDAs). We succeeded in synthesizing ∗BEA zeolite from FAU zeolite after hydrothermal treatment for only 2 h at 125 °C in the presence of tetraethylammonium hydroxide (TEAOH) and 33 wt.% seed crystals. Moreover, ∗BEA zeolite synthesis was similarly achieved with benzyltrimethylammonium hydroxide (BTMAOH). We also succeeded in the interzeolite conversion of FAU zeolite into ∗BEA zeolite without OSDAs, which, to our knowledge, is the first such conversion; KOH (∗BEA zeolite yield: ca. 34%) and NaOH were effective as alkali sources. Our results suggest that zeolite formation processes via such interzeolite conversions are more efficient with enhanced crystallization rates, and further, OSDA-free conversions are possible.

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► FAU−∗BEA interzeolite conversion was investigated in the presence of seed crystals.
► Highly crystalline and pure ∗BEA zeolites were obtained using BTMAOH instead of TEAOH.
► Interzeolite conversion of FAU zeolite into ∗BEA zeolite without OSDAs also occurred.