亚临界干燥法制备TiO2/SiO2复合气凝胶及其光催化性能研究

Preparation of TiO/SiO composite aerogel by subcritical method and its photocatalytic activity

以正硅酸乙酯(TEOS)和钛酸四丁酯(TnBT)为原料,去离子水和无水乙醇为溶剂,盐酸、甲酰胺为催化剂,通过酸/碱两步溶胶-凝胶法制得TiO2/SiO2复合醇凝胶,经过老化、溶剂置换等后续工艺,在亚临界条件下干燥制备不同TiO2/SiO2比的复合气凝胶。采用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、BET比表面积、热重-差示量热(TG-DSC)和红外光谱(FT-IR)等手段对气凝胶进行了表征。并将制备的TiO2/SiO2复合气凝胶用于紫外光催化降解甲基橙。结果表明:不同TiO2/SiO2比的复合气凝胶经过500℃煅烧之后,n(Ti)∶n(Si)=1∶1时其比表面积最高达480.61m^2/g,其组成为无定形SiO2和锐钛矿TiO2。紫外光催化降解甲基橙实验表明,采用亚临界干燥制备得到的TiO2/SiO2复合气凝胶,其催化降解率可达到99.6%,表现出优异的催化性能。

TiO2/SiO2 composite aerogels were prepared from ethyl orthosilicate (TEOS)and butyl titanate(TnBT)as raw materials,deionized water and absolute ethanol as solvent,hydrochloric acid,ammonia and formamide as the catalysts.The SiO2and TiO2/SiO2composite alcohol gels were prepared by acid/base two step sol-gel method.After aging,solvent replacement and other subsequent processes,TiO2/SiO2 aerogels were prepared by subcritical conditions.The aerogels were characterized by SEM,TEM,XRD,BET,TG-DSC and FT-IR.The prepared aerogels were used for ultraviolet photocatalytic degradation of methyl orange.The results shown that the aerogels with different TiO2/SiO2ratios had a specific surface area of 480.61m^2/g when n(Ti)∶n(Si)=1∶1after being calcinated at 500℃.Its composition was amorphous SiO2 and anatase TiO2.UV-catalyzed degradation of methyl orange showed that the aerogels which prepared by subcritical drying had the catalytic degradation rate up to 99.6%,and exhibited excellent catalytic performance.