Influence of silica source on zeolite synthesis in the presence of 1-butanol

Synthesis of high-silica zeolites in the presence of 1-butanol (n-BuOH) was conducted under various conditions to explore the role of silica source, a ging time, and n-BuOH. It was found that the solubility of the silica source in the aqueous phase was a critical factor for the formation of zeolite precursor when KOK was e mployed as an alkali source. MFI (ZSM-5) type zeolites were obtained when f umed silica with small BET specific surface area was employed, whereas TON (Theta-1) type zeolites were formed when fumed silica with large BET specif ic surface area was employed. It was also found that the addition of n-BuOH suppressed the formation of cristobalite. This is probably due to the redu ction of the Si concentration in the aqueous phase of the synthesis gel. FT -IR and C-13 CP MAS NMR measurements of as-made zeolites suggested that n-B uOH molecules were occluded in the zeolitic pores of TON and MFI type zeoli tes at the initial stage of crystallization.