Studies on Synthesis and Pervaporation Performance of Boron-Substituted MFI Zeolite Membranes

Boron-substituted MFI (B-MFI) zeolite membranes were synthesized on low-cost porous mullite tubes by secondary growth. The as-synthesized membranes and powders were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), Inductive coupled Plasma Emission Spectrometer (ICP-AES), (FTIR) B-11 magic angle spinning nuclear magnetic resonance (B-11 MAS NMR) and scanning electron microscope (SEM). The effects of n(B)/n(SiO2) ratio in gel, feed temperature and concentration on pervaporation (PV) for acetone/water mixtures through B-MFI zeolite membranes were also investigated. The results of characterization verified BO4 substituted SiO4 in MFI framework. n(B)/n(SiO2), ratio in gel took great effects on the microstructure and PV performance of B-MFI zeolite membrane. B-MFI zeolite membranes could permeate selectively organics from water with acetone and ethanol separation factors of 260 and 70 for 5% (w/w) acetone/water and 5% (w/w) ethanol/water binary feeds at 60 degrees C, which were higher than those through a silicalite-1 membrane prepared under the same synthesis condition.