Open-pore MFI zeolite nanosheets were prepared by removal of organic structure-directing agents (OSDA) from a multilamellar MFI zeolite (ML-MFI) using a mixture of 95%~98%(w/w)H2SO4 and 30%(w/w)H2O2 with VH2SO4∶VH2O2=3∶1 (known as piranha solution), followed by ultrasonication for exfoliation and sedimentation for purification. The exfoliated MFI zeolite nanosheets were characterized by various techniques, such as X-ray diffraction (XRD), scanning electron microscope (SEM), transmittance electron microscope (TEM), N2 adsorption-desorption, Fourier transform infrared spectrometer (FT-IR) and thermal gravimetric analyzer (TGA), etc., indicating that OSDA was removed after the piranha solution treatment and dispersed, open-pore MFI nanosheets were obtained followed by exfoliation through ultrasonication. Continuous MFI nanosheet membranes were prepared by depositing the open-pore MFI nanosheets on home-made alumina disc supports by a simple vacuum-assisted filtration method. Single gas permeance tests on the MFI zeolite nanosheet membranes indicated that ideal selectivities for n-butane over i-butane of 4.1~5.8 with a permeance of n-butane of 2.2×10^-7~4.1×10^-7 mol·m^-2·s^-1·Pa^-1 were achieved.
Chinese Journal of Inorganic Chemistry