Al2O3-SiO2复合膜的制备与结构表征

以异丙醇铝和正硅酸乙酯为主要原料,用溶胶-凝胶法制备无支撑体Al₂O₃-SiO₂复合膜.应用XRD、DTA-TGA、IR、BET等测试手段对复合膜的物相组成、热稳定性、孔结构进行表征.并且讨论了化学组成和煅烧温度对复合膜孔结构的影响.研究结果表明:550℃煅烧10h的复合膜物相组成为无定形的SiO₂和γ-Al₂O₃晶体,粒度大小在2-4nm之间,化学组成为Al₂O₃/SiO₂=3:2的复合膜在不同煅烧温度时,400℃煅烧的物相为γ-AlOOH和,γ-Al₂O₃,550-1150℃煅烧的物相为γ-Al₂O₃,1220℃煅烧的物相为γ-Al₂O₃和α-Al₂O₃,1300℃煅烧的物相为莫来石相和α-Al₂O₃;化学组成不同的复合膜主要是由Al-O网络和Si-O网络构成,没有形成Al-O-Si网络结构;复合膜具有良好的热稳定性;化学组成和煅烧温度对复合膜的孔结构有一定的影响.

Preparation and Structural Characterization of Al2O3-SiO2 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-SiO_₂ 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.