Al_2O_3-SiO_2复合膜的制备与结构表征

Preparation and Structural Characterization of Al_2O_3-SiO_2 Composite Membrane

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.

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-A2O3 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.