FAU–LEV interzeolite conversion in fluoride media

The influence of fluoride anions on the interzeolite conversion of FAU zeolite into LEV zeolite was investigated by using choline hydroxide and 1-adamantanamine as structure-directing agents (SDAs) under various hydrothermal synthesis conditions. This is the first report on FAU−LEV interzeolite conversion in the presence of fluoride media. In the case in which choline hydroxide was used, no pronounced influence of fluoride anions was observed, which indicates the stronger mineralizing ability of hydroxide anions as compared with fluoride anions. When 1-adamantanamine was used, however, the influence of fluoride anions was clearly observed. The LEV zeolite obtained using 1-adamantanamine exhibited high thermal stability as compared with that obtained using choline hydroxide. Large differences were also observed between the decomposition/dissolution behavior of the starting FAU zeolite in the two interzeolite conversions, as well as between the nucleation and crystal growth process of LEV zeolites when choline hydroxide and 1-adamantanamine were used as SDAs.

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► FAU−LEV interzeolite conversion was investigated in fluoride media.
► Complete FAU−LEV interzeolite conversion occurred when 1-adamantanamine was used as a SDA.
► The LEV zeolite exhibited high thermal stability.