表面含磺酸基的介孔分子筛SBA-15-SO_3H的直接合成

Direct Synthesis of SBA-15 Mesoporous Silica Functionalized with Sulfonic Acid Groups

采用水热法直接合成了含磺酸基的介孔分子筛SBA 15 SO3H .XRD表征结果表明 ,该分子筛具有规则的、六方立柱形的中孔结构 ,通过酸碱滴定和XRD确定了正硅酸乙酯 /有机硅的最佳合成配比为 9(α =0 1) .2 9SiMASNMR固体核磁结果表明 ,含磺酸基的有机基团Si (CH2 ) 3 SO3H中的硅与SBA 15骨架上的氧通过Si O键结合 ,形成稳定的有机 /无机组成 ,FT IR谱表明 :在SBA 15 SO3H表面含有质子酸中心 SO3H .N2 吸附 脱附和TEM结果表明 ,SBA 15 SO3H具有较大的比表面积、孔容和孔径 ,孔大小是单一的 ,孔分布是高度有序的 .酯化反应结果表明 ,与后合成法相比 ,直接法合成的催化剂既具有较高的稳定性 ,又具有简便。

Well-ordered, mesoporous, organic-inorganic hybrid SBA-15-SO_3H containing alkyl (methyl) and sulfonic acid groups was directly synthesized via sol-gel technique and characterized by XRD, 29Si MAS NMR, FT-IR, N_2 adsorption, TGA and TEM. The optimum synthetic ratio of MPTMS to TEOS (α=0.1) was obtained. The (CH_2)_3-SO_3H moiety is covalently linked via a nonhydrolyzable Si-C bond to a siloxane species, which is hydrolyzed to form the silica framework of SBA-15 that has 2-D hexagonal structure. The acid site of (CH_2)_3-SO_3H belongs to strong Brnsted type. The surface area of SBA-15-SO_3H (α=0.1) is 801 cm 2/g, total pore volume is 0.93 ml/g and pore size is about 8.2 nm. The pores of SBA-15-SO_3H are well-ordered and regular hexagonal array. The temperature for -SO_3H decomposition is higher than 300 ℃. The catalytic results showed that SBA-15-SO_3H is an efficient catalyst for esterification of methanol with oleic acid. The SBA-15-SO_3H catalyst has the highest activity among the mesoporous silica functionalized by sulfuric acid groups. The SBA-15-SO_3H has higher stability than p-SBA-15-SO_3H post synthesized conventionally. The direct synthesis method is more simple, convenient and efficient, compard with the post synthesis.