Solvent-Free Secondary Growth of Highly b‑Oriented MFI Zeolite Films from Anhydrous Synthetic Powder

Up to date, zeolite films have been mainly fabricated by in situ crystallization, secondary growth in a solution/hydrogel, or occasionally by vapor phase transformation of dry gel. Here we demonstrate for the first time a solvent-free secondary growth method for b-oriented silica MFI zeolite films using the synthetic powder from ground anhydrous raw solids in the presence of NH4F. Typically, precisely b-oriented MFI zeolite films are synthesized from seed layers of highly b-oriented MFI zeolite crystals in the synthetic powder of 1SiO2:0.035TPABr:0.05NH4F at 175 °C for 6 h. If needed, b-oriented MFI zeolite multilayer films can be acquired by changing the synthesis time or the amount of NH4F in the synthetic powder. Compared with the traditional hydrothermal synthesis, the approach developed here may provide a new avenue for fabricating high quality zeolite films/membranes.