以阳离子Gemini表面活性剂C_(12-2-12)为模板合成纯硅立方介孔材料

Synthesis of cubic mesoporous Silica materials using cationic Gemini surfactant C_(12-2-12)

用Germini表面活性剂[C12H25N+(CH3)2-(CH2)2-N+(CH3)2C12H25]·2Br-作模板合成了立方结构的介孔二氧化硅,并且用小角X射线衍射和氮气吸附-脱附技术对样品进行了表征.结果表明,所得到的介孔二氧化硅为立方结构,晶胞参数在8.45-8.57 nm之间;孔道的有序性随表面活性剂与Na2SiO3比例的增大而增加.氮气吸附-脱附等温线为第Ⅳ类型的等温线,在相对压力p/p0=0.15-0.25和P/p0=0.8-1的范围内出现两个H1型滞后环,分别是由介孔孔道和颗粒之间的空穴引起的.BET表面积也随表面活性剂与Na2SiO3比例的增大而增大,最大可达1 100m2/g,最可几孔径在2.20 nm左右.

Cubic mesoporous silicas were synthesized using Gemini surfactant [C12H25N+ (CH3 )2- (CH2 )2-N+ (CH3 )2C12H25]·2Br- (abbreviated as C12_2-12). The resulting samples were researched by small angle X-ray diffraction (SXRD) and Nitrogen ad-sorption-desorption technique. The results showed that the structure of the resulting mesoporous silica belonged to cubic structure, the constant of unit cell of cubic structure was between 8.47-8.57 nm. Ordering of pore structure increased with the increase of the molar ratio of C12-2-12 to Na2SiO3 . Type Ⅳ isotherm occurred in nitrogen adsorption-desorption curves, indicated that pore size of the resulting cubic structure was in the range of mesopore. There were two H1 hysteresis loops in the range of relative pressure p/ p0 =0.15-0.25 and p/p0 = 0.8-1.0, corresponded to primary pores of pore channels of mesoporous materials and voids between particles respectively. With the increase of the molar ratio of C12-2-12 to Na2 SiO3, BET specific surface area increased, and the maximum of BET specific surface area was above 1100 m2 /g. The most probable pore size was about 2.20 nm.