缓冲溶液中制备掺杂高度隔离铁物种的介孔氧化硅(英文)

Preparation of Fe-substituted Mesoporous Silicas with Highly Isolated Iron Species in Buffer Solution

使用P123作为模板剂,采用不同的硅源(正硅酸甲酯,正硅酸乙酯,硅酸钠)在弱酸性的条件下(pH=4.4,乙酸-乙酸钠缓冲溶液)合成掺杂铁的介孔氧化硅材料.正硅酸甲酯和硅酸钠形成有序的二维六方相的介孔结构,而正硅酸乙酯形成了囊泡结构.紫外可见漫反射光谱和紫外共振拉曼光谱表明,在环境友好的条件下,采用硝酸铁和硅酸钠可以合成出高度隔离的铁物种.缓冲溶液提供了一条便捷的途径,通过简单改变硅源来控制介孔结构.掺杂铁的介孔氧化硅材料在苯酚的羟化反应中表现出优异的催化性能,主要由于铁物种高度分散在氧化硅载体上,介孔结构使铁活性位更易于接近反应物分子.

The iron-substituted mesoporous silicas were synthesized under mild acidic conditions（pH=4.4,HOAc-NaOAc buffer solution） using tetramethoxysilane（TMOS）,tetraethoxysilane（TEOS） or sodium silicate solution as silica source in the presence of block copolymer pluronic P123 as the mesoporous template.TMOS and sodium silicate led to iron-containing silicas with ordered two-dimensional hexagonal mesoporous structure,and vesicle mesostructure was obtained using TEOS as silica precursor.UV-Vis and UV resonance Raman spectra show that highly isolated iron species can be predominantly obtained on mesoporous iron-containing silicas synthesized using inexpensive sodium silicate and Fe（NO3）3 as precursors.The buffer solution provides a facile strategy for controlling the mesostructure of iron-containing silicas by simply varying the silica source.Mesoporous iron-substituted silicas are highly efficient in hydroxylation of phenol because of a high dispersion of active iron centers within silica matrices and a high accessibility of active iron species to reactants.