Feng Ye-Fei, Yang Xiao-Yu, Di Yan, Du Yun-Chen, Zhang Yong-Lai, Xiao Feng-Shou
College of Chemistry & State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, Changchun 130023, China.
J Phys Chem B. 2006 Jul 27;110(29):14142-7. doi: 10.1021/jp061839p.
Mesoporous silica materials (HS-JLU-20) with an extremely high content of mercaptopropyl groups have been successfully synthesized using fluorocarbon-hydrocarbon surfactant mixtures through a simple co-condensation approach of tetraethyl orthosilicate (TEOS) and (3-mercaptopropyl)trimethoxysilane (MPTS), which are characterized by X-ray diffraction (XRD), nitrogen adsorption and desorption isotherms, transmission electron microscopy (TEM), CHNS elemental analysis, thermogravimetry analysis (TGA), and (29)Si NMR spectroscopy. The results show that HS-JLU-20 samples with molar ratios of MPTS/(MPTS + TEOS) at 0.5-0.8 in the starting synthetic gels still show their mesostructures, while HS-SBA-15 with the molar ratio of MPTS/(MPTS + TEOS) at 0.50 completely loses its mesostructure in the absence of fluorocarbon surfactant. Possibly, fluorocarbon surfactant containing N(+) species with a positive charge could effectively interact with negatively charged mercapto groups in the synthesis of HS-JLU-20 materials, resulting in the formation of mesoporous silicas with good cross-linking of silica condensation even at an extremely high content of organic mercapto groups. More interestingly, after the treatment with hydrogen peroxide, HSO(3)-JLU-20 materials with an extremely high content of organic sulfonic groups exhibit comparable activity with liquid concentrated sulfuric acid in catalytic esterification of cyclohexanol with acetic acid.
通过氟碳 - 烃表面活性剂混合物，采用正硅酸乙酯（TEOS）和（3 - 巯丙基）三甲氧基硅烷（MPTS）的简单共缩聚方法，成功合成了具有极高巯丙基含量的介孔二氧化硅材料（HS - JLU - 20），并通过X射线衍射（XRD）、氮吸附和解吸等温线、透射电子显微镜（TEM）、CHNS元素分析、热重分析（TGA）和（29）Si核磁共振光谱对其进行了表征。结果表明，起始合成凝胶中MPTS/（MPTS + TEOS）摩尔比为0.5 - 0.8的HS - JLU - 20样品仍显示出其介孔结构，而MPTS/（MPTS + TEOS）摩尔比为0.50的HS - SBA - 15在没有氟碳表面活性剂的情况下完全失去其介孔结构。可能是，含带正电荷N（+）物种的氟碳表面活性剂在HS - JLU - 20材料的合成中能与带负电荷的巯基有效相互作用，即使在有机巯基含量极高的情况下也能形成具有良好二氧化硅缩合交联的介孔二氧化硅。更有趣的是，用过氧化氢处理后，具有极高有机磺酸基团含量的HSO（3） - JLU - 20材料在环己醇与乙酸的催化酯化反应中表现出与液体浓硫酸相当的活性。
