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

Synthesis of capillary titanosilicalite TS-1 ceramic membranes by MW-assisted hydrothermal heating for pervaporation application

Titanium silicalite-1 (TS-1) membranes were obtained on α-Al 2O3 capillaries by secondary growth of silicalite-1 seeds under microwave irradiation. TS-1 membranes were grown at 180-190 °C either on the outer side or on both sides of the capillaries, from sols with a molar ratio Si/Ti = 16-75. All the derived membranes were gas-tight before template calcination (no macro-defects) although the highest Si/Ti ratios lead to higher membrane quality with N2/SF6 > 100 for single gases and separation factors up to 65 for EtOH/H2O mixture separation by pervaporation (EtOH flux up to 2.2 kg/h m2 at 65 °C). The reproducibility of membrane performance, with good balance between flux and selectivity, is highly attractive for further industrial applications of these TS-1 membranes which are currently developed on multi-capillary modules