焙烧温度对氧化铝膜孔性能的影响

利用ＴＧ－ＤＴＡ、ＢＥＴ法分析研究了热处理过程的膜孔径分布、孔径大小及膜的比表面积、比孔容随焙烧温度的变化趋势，并用ＸＲＤ研究了氧化铝膜的膜内晶体的晶面取向，用ＴＥＭ、ＳＥＭ观察用溶胶─凝胶法制备的氧化铝膜的表面及截面形貌．发现构成氧化铝膜的微晶的择优取向度决定着膜孔径分布的均匀性，焙烧温度越高，膜微晶的择优取向度越大，膜的孔径分布越窄，但孔径增大．膜的比表面积、比孔容在４００℃有一最大值，４００℃是合适的膜催化、反应用膜的焙烧温度，这时膜比表面积、比孔容和孔隙率分别为２８３ｍ^２／ｇ、０．３３８ｍＬ／ｇ和５３％．７００℃是分离用膜的合适焙烧温度，这时膜比表面积、比孔容和孔隙率分别为２０２ｍ^２／ｇ、０．２０３ｍＬ／ｇ和４５％．７００℃时膜的最大孔径为５ｎｍ；孔径为１～１．２５ｎｍ的孔占孔体积的７０％以上．

Influence of Firing Temperature on Pore Characteristics of Alumina Membranes

The physical and chemical characteristics, pore radius, pore size distribution and surface areapore volume, porosity of the membrane prepared by sol-gel method using aluminum isoproxide were studied using TG--DTA, BET at different firing temperature from room temperature to1000 . The preferred orientation of alumina micrograin of the alumina membrane was studied byXRD. The surface and cross--section were observed by TEM and SEM. The pore size distributionare influenced by preferred orientation of alumina micrograin. The higher the firing temperature,the higher the degree of the preferred orientation, the more the uniformity of the pore size distribution of the membrane, the bigger the largest the pore radius of the membrane. 400 is suitablefiring temperature of the membrane used as membrane catalysis and/or membrane reaction withthe largest the surface area, pore volume and porosity of 283m2/g, 0.338mL/g and 53%. 700 issuitable firing temperature of the membrane used as separation with the surface area, pore volumeand porosity of 202m2/g, 0.203mL/g and 45%. The largest pore radiu is sum, pore with radius of1~1.25nm is above 70% pore volume at 700 .