以EDTANa2为矿化剂近中性条件下室温合成介孔二氧化硅

利用EDTANa2作为矿化剂, 在近中性条件下于室温合成了厚壁(约3 nm)蠕虫介孔分子筛. 在反应物配比为n(CTAB):n(TEOS):n(EDTANa2):n(H2O)=(0.05~0.2):(0.1~2):(0.1~0.5):(100~500)范围内都能得到介孔二氧化硅. 以XRD、N2吸附、FTIR、SEM和TEM详细考察了体系配比和温度对介孔二氧化硅结构和形貌的影响, 发现CTAB用量越大, 介孔d值相应增大. 温度对介孔二氧化硅的结构和形貌有很大的影响, 温度在2~15 ℃范围内都能生成孔径分布较规则的介孔, 介孔材料的形貌随温度的升高由空心管变成小颗粒聚集体; 合成的介孔分子筛中的模板剂可以通过乙醇萃取的方式除去. 提出了介孔的生成遵从(S+-E-)0-I0中性模板机理.

Synthesis of Mesoporous Silica at Room Temperature and Near-neutral pH with EDTANa2 as Mineralization Agent

Using EDTANa2 as mineralization agent, mesoporous silicas with wormlike mesopores and thick pore wall(about 3 nm) were facilely synthesized at room temperature and near-neutral pH. The mesoporous silica can be obtained with reactants molar composition range of n(CTAB):n(TEOS):n(EDTANa2):n(H2O)=(0.05—0.2):(0.1—2):(0.1—0.5):(100—500). XRD, N2 sorption, FTIR, SEM and TEM methods were carried out to investigate the topological and morphological properties of the mesoporous silicas. As the amount of CTAB increased, the d spacing value of mesoporous silica increased correspondingly. Temperature has a great effect on the synthesis of mesoporous silica. When temperature increased from 2 ℃ to 20 ℃, morphologies of the mesoporous silica varied from hollow micro-tubes to granule aggregates. Based on the experiments, a modified neutral mechanism of (S+-E-)0-I0 was proposed.