Preparation of porous SiO2 membranes on porous stainless steel supports

In order to explore the membrane formation properties of silica membranes on porous stainless steelsupports with mean pore size of 1 μm, tetraethyl orthosilicate (TEOS) was employed to prepare the silica sol via colloidal gel route of sol-gel method. The effects of the amount of ammonia, the peptization temperature and the peptization period on the sol properties were investigated. In addition, the effects of the aging period of the sol, the kind of binders, the concentration of the casting solution and sintering temperature on the morphologies and phases of the top membranes were also discussed. The results show that the optimal amount of ammonia is 2.1 mol/mol, the optimal peptization temperature is 50℃, and the optimal peptization period is 12 h. The optimal parameters for membrane preparation are as follows: the aging period of the sol 24 h, the binder PVA 1750, the concentration of the casting solution 0.047 mol/L and the sintering temperature 850℃. Under these conditions, pure tridymite phase of grain-like silica membranes can be obtained.