Thin-sheet zeolite membrane and methods for making the same
Zeolite membrane sheets for separation of mixtures containing water are provided, as well as methods for making the same. Thin, but robust, zeolite membrane sheets having an inter-grown zeolite crystal film directly on a thin, less than 200 micron thick, porous support sheet free of any surface pores with a size above 10 microns. The zeolite membrane film thickness is less than about 10 microns above the support surface and less than about 5 microns below the support surface. Methods of preparing the membrane are disclosed which include coating of the support sheet surface with a seed coating solution containing the parent zeolite crystals with mean particle sizes from about 0.5 to 2.0 microns at loading of 0.05-0.5 mg/cm2 and subsequent growth of the seeded sheet in a growth reactor loaded with a growth solution over a temperature range of about 45° C. to about 120° C.
1. A hydrocarbon-permeable membrane sheet for selective removal of hydrocarbon molecules from a mixture comprising:
a hydrocarbon-selective membrane layer comprising inter-grown MFI-type zeolite crystals comprising SiO2/Al2O3 and disposed on a support surface of a porous metal-based support sheet, wherein the porous metal-based support sheet is less than 200 μm thick and is substantially free of surface pores greater than 10 μm in diameter, wherein substantially free is less than 1% of the surface,
wherein the membrane layer has thickness above the support surface in the range of about 2 to 20 μm and has a penetration depth below the support surface in the range of about 1 μm to about 10 μm,
wherein the permeable membrane sheet has a hydrocarbon permeance greater than 1×10-6 mol/m2/Pa/s and a hydrocarbon selectivity greater than 2, and
wherein the membrane sheet is bendable from a substantially flat configuration to a configuration having a radius greater than ½″ (1.3 cm) without cracking.
2. The membrane sheet of claim 1 , wherein the hydrocarbon-selective membrane layer is configured to remove alcohols from alcohol-water mixtures.
3. The membrane sheet of claim 1 , wherein the porous metal-based support sheet has a porosity between 15 and 55%.
4. The membrane sheet of claim 1 , wherein the porous metal-based support sheet has a porosity between 30 and 45%.
5. The membrane sheet of claim 1 , wherein the porous metal-based support sheet comprises greater than 60% by weight of Ni, an Ni alloy, or stainless steel.
6. The membrane sheet of claim 1 , wherein the MFI-type zeolite crystals have a SiO2/Al2O3 molar ratio greater than 100.