Preparation and Structural Characterization of Al_2O_3-SiO_2 Composite Membrane

Al2O3-SiO2 composite membrane was prepared by sol-gel process using aluminium isopropoxide and tetraethoxysilane as raw materials. The phase constitution, thermal stability, and the pore structure were characterized by means of XRD, DTA-TGA, IR, BET etc. The results show that the phase constitution of the composite membrane was SiO2 and γ-Al2O3 after calcined at 550℃ for 10h, and the particle size range from 2nm to 4nm. The XRD results of the composite membrane (Al2O3/SiO2=3:2) calcined at different temperatures show that the membrane is constituted of γ-AlOOH and γ-Al2O3 at 400℃, γ-Al2O3 at 550℃ to 1150℃, γ-Al2O3 and α-Al2O3 at 1220℃, mullite and α-Al2O3 at 1300℃. Al2O3-SiO2 composite membrane is constituted of Al-O and Si-O networks, and no Al-O-Si network found membrane. The composite membrane has high thermal stability, and the pore structure of the membrane can influence on its constitution and the thermal treatment temperatures.