摘要
以自制的Nafion溶液、正硅酸乙酯为原料 ,通过溶胶 -凝胶方法 ,将Nafion纳米颗粒分散组装到多孔性SiO2 中 ,制得高比表面积纳米复合物Nafion/SiO2 固体酸催化剂 ,大大提高了Nafion所含酸性中心 (即磺酸基 )的暴露率和可接近程度 .在非极性溶剂正庚烷和甲苯中 ,13 %Nafion/SiO2 固体酸对α 生育酚的合成具有很好的选择催化作用 (产率超过 90 % ) .相对于致密性Nafion树脂而言 ,13 %Nafion/SiO2 纳米复合物单位酸中心的催化活性增加了
The 13% Nafion/SiO 2 nanocomposite with hi gh surface area was prepared by entrapping Nafion resin nanoparticles in a porou s silica (viz. an in situ sol-gel method) and used as a catalyst for th e synthesis of α-tocopherol by the Friedel-Crafts alkylation-condensation re action of trimethylhydroquinone and isophytol. The catalytic results were compar ed with those obtained over Nafion NR50 resin catalyst. Due to the increased accessibility to the reactants of Nafion resin-based acid sites, the nanocomp osite showed remarkbly enhanced activity for α-tocopherol synthesis (yield > 90%) in nonpolar toluene and n-heptane solvents. The activity per unit weig ht of Nafion resin in toluene solvent was found to be 10 times higher in the nan ocomposite than in Nafion NR50 resin. The nanocomposite catalyst proved to be recoverable from the reaction, but a gradual loss of the catalytic activi ty was observed with increasing the recycle number.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2003年第10期1667-1670,共4页
Acta Chimica Sinica
