Synthesis of titania composite membranes by the pressurized sol-gel technique

Crack-free titania composite membranes have been synthesized from colloidal titania sols (average particle size of 7-16 nm) by the pressurized sol-gel coating technique. The Knudsen permeability of N-2 through the titania membrane layer heat-treated at 300 degrees C is about 21 x 10(-7)-35 x 10(-7) mol/m(2) . s . Pa at room temperature. The permselectivity and the separation factor of He to O-2 in the temperature range of 25 degrees-245 degrees C are 2.49-2.74 and 1.66-1.84, respectively. The average pore diameters of these membranes estimated from the molecular weight cutoff data (6000-9000) using poly(ethylene glycol) are 3.0-4.0 nm. By doping zirconia into titania membranes, their thermal stability could be improved up to 800 degrees C.