Microwave-assisted hydrothermal rapid synthesis of capillary MFI-type zeolite-ceramic membranes for pervaporation application

The supported zeolite membranes prepared in this work have been synthesised under microwave heating in order to reduce synthesis time, to prevent support dissolution, and to reproducibly obtain a thin defectfree zeolite layer. The MFI-type zeolite membranes were synthesised on ceramic capillaries, with a high membrane surface area-to-volume ratio (>1000 m2 m−3), which is by far higher than that of classical tubular supports (500 m2 m−3). The selective layer was deposited inside, outside or on both sides of the capillaries. These hydrophobic membranes were characterized and tested in pervaporation for the separation of an EtOH/H2O: 5/95 wt.% mixture. The best results obtained at a pervaporation temperature of 45 ◦C, in terms of flux (1.5 kg/h m2) and selectivity (˛EtOH/H2O = 54), were achieved with the doublesided membranes.This work has been performed in Hyflux CEPAration Technologies (preparation of supports), IEM and UNIZAR, thanks to the financial support of both the European Commission (through the NanoMemPro Network of Excellence) and Hyflux CEPAration Technologies (Europe).Peer reviewe

Coupling microwave-assisted and classical heating methods for scaling-up MFI zeolite membrane synthesis

Silicalite-1 (S-1) nano-seeds obtained by microwave-assisted (MW) heating have been used to coat industrial supports and to up-scale the synthesis of MFI zeolite membranes by secondary growth applying a classical heating (CH) method. The MW-assisted method was adapted/optimized for fast synthesis and high yield of uniform and non-aggregated S-1 nano-seeds suspensions which were directly used for seeding macroporous industrial α-Al 2O 3- based supports by dip-coating. The CH secondary growth yielded uniform MFI membranes, by applying optimal reaction conditions while minimizing the reaction time and consumption of chemicals. The protocol coupling MW-assisted and classical heating in zeolite membrane synthesis revealed high reproducibility and has been validated on various industrial ceramic supports: single tubes (Pall-Exekia, Atech, Inocermic, CTI) and also single capillaries and capillary bundles, from Hyflux, providing a higher surface/volume ratio (typically S/V>100m 2/m 3). Membrane homogeneity has been validated by both SEM and single gas permeation measurements with N 2 and SF 6. The N 2/SF 6 ideal selectivity was used to predict the ethanol/water separation factor for the prepared MFI membranes