混合超分子液晶模板法合成六方介孔相含钛氧化硅

Synthesis of Hexagonal Mesostructured Titanium- containing Silica by Mixed Supramolecular Templating

采用混合十六烷基三甲基溴化铵（ CTAB）与不同碳链的脂肪胺（ CnNH2n＋ 3， n=8,10,12,14,16）作模板，在四甲基氢氧化胺为碱源的条件下，合成了具有六方介孔结构的含钛氧化硅 Ti- MCM- 41分子筛材料 . XRD和 TEM测试表明所合成材料具有高度的长程有序结构，样品的 N2吸附 /脱附等温线表明 ,高度有序的 Ti- MCM- 41材料展示了毛细凝聚的陡峭台阶和狭窄的介孔孔径分布 .对反应物配比中 Ti/Si比、脂肪胺碳链长度 n对六方介孔相结构的影响进行了研究，实验发现当 Ti/Si< 0.15和 n< 16时，均可获得具有六方介孔结构的含钛氧化硅 Ti- MCM- 41；而当 Ti/Si≥ 0.15或 n >16时，产物将分别发生从六方向无定形态或从六方向层状介孔相结构的转移，从混合表面活性剂的堆积参数对这种相转移现象进行了分析 .

Using the mixture of cetyltrimethylammonium bromide(CTAB) and neutral alkylamine surfactant (CnNH2n+3, n = 8, 10, 12, 14, 16) as templated, hexagonal mesostructured titanium-containing silica Ti-MCM-41 was synthesized. XRD and TEM provided direct evidence for a well-ordered hexagonal nano pore structure. Nz adsorption/desorption isotherm showed that highly ordered Ti-MCM-41 materials exhibited sharp steps of capillary condensation and narrow pore size distributions. The effect of the ratio of titanium to silica(Ti/Si) and the chain length n of the alkylamine on the mesostructure were investigated, It was revealed that phase transition from hexagonal to amorphous structure occured with Ti/Si > 0.15 and from hexagonal to lamellar structure appppeared with n = 18.