Methanol vapor separation through the silica membrane prepared by the CVD method with the aid of evacuation

Two types of the silica membrane were prepared by the CVD with the aid of e vacuation. Porous glass tubes with outer diameter of 5 mm, inner diameter o f 4 mm were used as supports. Mean pore diameters of the supports were 4 mn (CVD-1) and 2 nm (CVD-2), respectively. Tetraethoxysilane (TEOS, Si(OC2H5) (4)) and oxygen were used as reactants. The inside of the membrane modules were evacuated with a vacuum pump to deposit silica near the pores preferen tially. Due to evaluate methanol vapor separation, mixed gas separation of the membranes were measured using H-2-10%CH3OH and CO-10%CH3OH gas mixtures at 373 and 473 K. At 473 K, the separation factors of H-2/CH3OH were about 6 for CVD-1 and about 20 for CVD-2. These value were higher than that of t he porous glass membrane with mean pore diameter of 4 mn (H-2/CH3OH = 1.2). The separation factor for CVD-2 was about 5 times as large as the theoreti cal Knudsen value (H-2/CH3OH = 4). (C) 2001 Elsevier Science B.V. All right s reserved.