Imidazolium-based ionic liquids as novel organic SDA to synthesize high-silica Y zeolite

• High silica Y zeolite was synthesized using imidazolium salt as novel organic SDAs.
• Imidazolium cations can partially replace the sodium cations of the Y zeolite framework.
• Y zeolite synthesized with [E(B)MIm]Br as SDAs displayed higher thermal stability.

Alkyl-substituted imidazolium-based ionic liquid as a novel type of organic structure-directing agent (SDA) was employed to synthesize high-silica Y zeolite with a SiO2/Al2O3 ratio of approximately 6.20–6.40. The XRD, SEM, BET and 27Al NMR characterizations showed that the products synthesized with the ionic liquids 1-ethyl-3-methylimidazolium bromide or 1-butyl-3-methylimidazolium bromide were highly crystalline pure phase Y zeolite. Moreover, the TG, TOC, XRF and 13C NMR results suggested that 1-ethyl-3-methylimidazolium or 1-butyl-3-methylimidazolium cations were trapped within the pores of the faujasite structure and played the role of structure-directing agents. 1-Ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium cations can partially replace the sodium cations to balance the negative charges of the zeolite framework, which facilitated the formation of a high SiO2/Al2O3 ratio faujasite structure.

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