Fabrication of zeolite NaA membranes on hollow fibers using nano-sized seeds exfoliated from mesoporous zeolite crystals

• Micro-sized crystals of mesoporous zeolite NaA can be easily smashed.
• Seed suspension of nanocrystals was obtained from grinded crystals.
• Zeolite NaA membranes were prepared with the seed suspension of nanocrystals.
• Zeolite membranes on hollow fiber supports showed high performance.

Micro-sized crystals of mesoporous zeolite NaA (meso-NaA) are prepared and their mechanical strength is compared with conventional NaA crystals. Crystals are characterized by nitrogen adsorption, X-ray diffraction, scanning electronic microscopy and dynamic light scattering. It is found that micro-sized meso-NaA crystals composed by numerous domains of interconnected nanocrystals can be easily smashed by hand-grinding, showing lower mechanical strength than conventional crystals. The suspension of zeolite NaA nanocrystals (∼110 nm) can be easily obtained after removing micro-sized crystals by centrifuging the suspension of the grinded crystals at 1000 rpm and can be used to seed hollow fiber supports. Zeolite membranes with high separation performance are obtained on the seeded hollow fiber supports by seeded growth. This method may open a new way to prepare zeolite nanocrystals for many applications.

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