苄基磺酸化MCM-41介孔分子筛的合成、表征及催化酯化性能

MCM-41介孔分子筛先后与苄基氯和氯磺酸接枝反应,得到苄基磺酸介孔分子筛(SBM)。通过X射线多晶衍射(XRD)、氮气吸附脱附、红外光谱(IR)、有机元素分析、扫描电镜(SEM)等方法对所得样品进行了表征。研究结果表明,MCM-41表面硅羟基与苄基氯反应,接枝量w(C)=6.68%;进一步磺化,接枝率w(S)=8.46%。XRD等分析结果表明,经过两步接枝反应,SBM仍然具有介孔结构特征,比表面积和孔容分别为366.9 m2/g、0.349 cm3/g。以SBM为催化剂,催化合成柠檬酸三丁酯;在n(酸)∶n(醇)=1.0∶9.0,w(催化剂)=3%,反应温度110℃,回流时间7 h的条件下,柠檬酸转化率可达93.2%;催化剂重复使用4次柠檬酸转化率为76.3%。

Synthesis, Characterization and Catalytic Activity in Esterification of Benzyl Sulphonic Acid Functionalized MCM-41

Benzylhydantoin sulfonic mesoporous(SBM) was obtained by grafting MCM-41 with benzyl chloride and chlorosulfonic respectively.The composition,structure and surface physical and chemical properties of the samples were characterized by means of elemental analysis(EDS),fourier transform infrared spectroscopy(FTIR),N2 adsorption-desorption,X-ray diffraction(XRD),transmission electron microscopy(TEM).The results of EDS and organic elemental analysis show that the grafting mass fraction of C was 6.68% for BM(sample MCM-41 Si—OH grafted with benzyl chloride).Further sulfonation produced S grafting mass fraction was up to 8.46% for SBM.The results show that,after two-step grafting reaction,SBM still had a mesoporous structure.The BET surface area was 366.9 m2/g and the pore volume was 0.349 cm3/g.The process for the synthesis of tri-n-butyl citrate using SBM as catalyst was studied.The results show that the yield was 93.2% under the conditions of n(acid)∶n(alcohol)=1.0∶9.0,w(Cat.)=3%,reaction temperature 110 ℃,reflux time 7 h.The catalyst can be reused,and after repeated use of four times,the esterification rate could still reach 76.3%.