摘要
以氨丙基 三乙氧基硅烷为有机硅源 ,采用共价接枝法 ,合成了杂化NH2 CH2 - CH2 - CH2 - SBA -15介孔分子筛 ,并用于催化苯甲醛与氰乙酸乙酯的Knoevenagel缩合反应 .反应结果表明 ,除个别有机基团负载量较高的样品外 ,该催化剂对Knoevenagel缩合反应有很高的催化活性 ,反应 75min后 ,苯甲醛的转化率可以达到 80 %以上 .此外 ,还考察了反应温度、溶剂、反应物配比和催化剂用量对反应活性的影响 ,以及催化剂的重复使用情况 .结果表明 ,反应可以在低于 75℃的温和条件下进行 ;有明显的溶剂效应 ;氰乙酸乙酯 /苯甲醛的摩尔比太高不利于反应的进行 ;反应活性不仅与催化剂上氨丙基活性中心的密度有关 ,而且与杂化分子筛的比表面积、孔径和孔容大小有关 .催化剂在重复使用三次时 ,苯甲醛的转化率仍可达到 6 0 %以上 .
The functionalized mesoporous molecular sieves were synthesized by using aminopropyltriethoxysilane to react with SBA-15, and were evaluated by using Knoevenagel condensation reaction of benzaldehyde with ethyl cyanoacetate as a model reaction. It was shown that the NH_2-CH_2-CH_2-CH_2-SBA-15 materials were effective catalysts with high activity for this reaction except a few samples with higher aminopropyl group loadings. After 75 min of reaction, the conversion of benzaldehyde reached 80%. In addition, effects of reaction temperature, solvent type, molar ratio of reactants and mass of catalyst on the activity and the recycling of the catalyst were also investigated. It was found that the reaction could be carried out under mild condition, solvent effect was obvious during the reaction, and there is an optimal value for the molar ratio of ethyl cyanoacetate to benzaldehyde. Catalytic activity of the reaction depended not only on the density of aminopropyl groups, but also on the BET surface area, pore diameter and pore volume of the funtionalized SBA-15. When the catalyst was used three times, the conversion of benzaldehyde could reach 60%.
出处
《分子催化》
EI
CAS
CSCD
北大核心
2005年第1期1-6,共6页
Journal of Molecular Catalysis(China)
