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480.61m2/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 SiO2 and TiO2/SiO2 composite 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/SiO2 ratios had a specific surface area of 480.61m2/g when n(Ti)∶n(Si)=1∶1 after 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.
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