常压干燥法制备TiO2气凝胶

以钛酸丁酯为原料, 乙酸为有机配体, 甲酰胺为干燥控制化学添加剂(DCCA), 采用溶胶-凝胶法和溶剂置换等后续工艺, 实现了块状TiO₂气凝胶催化剂的常压干燥法制备, 并考察了有机配体对气凝胶结构性能的影响。采用XRD、BET、SEM、EDS及DSC-TG对样品进行表征。结果表明: 当有机配体与钛酸丁酯物质的量之比为0.9时, 制备的样品性能最佳, 该TiO₂气凝胶样品为非晶态, 表观密度为0.25 g·cm^-3, 比表面积716.5 m²·g^-1, 平均孔径19.1 nm; 在850℃大气气氛下热处理2 h后, 比表面积为122.4 m²·g^-1, 平均孔径23.4 nm, 具有较高光催化活性; 经1000℃热处理后, TiO₂晶型仍为锐钛矿相, 热稳定性较好, 光催化活性有所降低。未采用有机配体制备的TiO₂气凝胶表观密度为0.57 g·cm^-3, 比表面积为482.2 m²·g^-1。有机配体的使用更有利于制备出表观密度较小、比表面积较高的TiO₂气凝胶。

TiO2 aerogel prepared by ambient pressure drying

Monolithic TiO 2 aerogels had been prepared by sol-gel method and subsequent process such as solvent replacement with ambient pressure drying using titanate tetrabutoxide, formamide and acetic acid as raw material. The influences of organic ligand on the structure of aerogels were also investigated. The microstructure and properties of samples were characterized by means of XRD, BET, SEM, EDS and DSC-TG al. The results indicate that when the molar ratio of organic ligand to titanium tetrabutoxide is 0.9, the property of prepared TiO2 aerogel is best, with the apparent density of 0.25g·cm -3 , the specific surface area of 716.5m 2 ·g -1 , and the average pore size of 19.1nm. After calcined at 850℃ in air for 2h, the sample has high photocatalytic activity, while its’ specific surface area reduces to 122.4m 2 ·g -1 and average pore size increases to 23.4nm. After calcined at 1000℃, anatase is still the main crystalling phase, and shows low photocatalytic activity. The apparent density of TiO 2 aerogel (not using organic ligand) is 0.57g·cm -3 , and its’ specific surface area is 482.2m 2 ·g -1 . TiO 2