Synthesis of zeolites with interconnected nanosheets
Interconnected zeolite nanosheets with a structural motif resembling self-pillared pentasil zeolites are synthesized through the use of MEL or MFI-type zeolites as crystalline seeds. The use of MEL- or MFI-type zeolites as crystalline seeds induces the spontaneous formation of pillared zeolites, thus avoiding, for the first time, the use of any organic or branching template for the crystallization of these hierarchical structures.
1 . A method for synthesizing zeolite interconnected nanosheets, comprising:
placing calcined zeolite seed crystals in an organic-free growth medium to form a growth solution, wherein the calcined zeolite seed crystals are MEL or MFI type zeolite seed crystals, wherein the organic-free growth medium consists essentially of silica and aluminum in sodium hydroxide, wherein the organic-free growth medium is free of organic structure directing agents, wherein the organic-free growth medium is free of branching templates, and wherein the organic-free growth medium has a ratio of molar compositions of A Na 2 O: B SiO 2 : C Al 2 O 3 : X H 2 O, wherein A is 3.4 to 3.5, wherein B is 18 to 25, wherein C is 1 to 1.4, and wherein X is 220 to 600;
allowing the calcined zeolite seed crystals to form zeolite interconnected nanosheets in the growth solution, wherein the zeolite interconnected nanosheets have a hierarchical, pillared morphology and a silicalite-2, ZSM-11, silicalite-1, or ZSM-5 framework; and
isolating the zeolite interconnected nanosheets from the growth solution.
2 . The method of claim 1 , wherein A is 3.42, B is 18, C is 1, and X is 224, 324, 424, or 600.
3 . The method of claim 1 , wherein A is 3.42, B is 24.62, C is 1.37, and X is 224, 324, or 443.
4 . The method of claim 1 , wherein the zeolite interconnected nanosheets have a thickness of 30 nm.