磁性介孔硅胶负载碱性离子液体催化剂的制备与性能

摘要

用巯丙基硅氧烷对磁性介孔硅胶改性，并通过烯丙基官能化离子液体的双键与巯基之间的自由基加成反应将具有不同侧链烷基的离子液体负载到磁性介孔硅胶表面，制备了磁性介孔硅胶负载碱性离子液体催化剂。采用红外光谱分析、X射线衍射、有机元素分析、氮气物理吸附/脱附分析和样品振动磁强计对催化剂的结构和磁性能进行了表征，最后通过催化三油酸甘油酯与甲醇酯交换反应对其催化性能进行了评价。结果表明，随着离子液体侧链烷基碳个数的增多，磁性介孔硅胶负载离子液体催化剂的离子液体负载量降低，比表面积和孔体积降低。当离子液体侧链烷基为辛基、十二烷基或十六烷基时，油酸甲酯产率均高于95%，并且反应3次后油酸甲酯产率依然高于90%。%Magnetic mesoporous silica was modified with 3-mercaptopropyl trimethoxysilane, and then ionic liquid with different alkyl chains was immobilized on magnetic mesoporous silicavia free radical addition reaction between sulfydryl group and double bond. The catalysts were characterized with FTIR, XRD, elemental analysis and vibrating sample magnetometer. Finally, the catalytic activity of the catalyst was evaluated through catalytic transesterification reaction of glycerol trioleate with methanol. Ionic liquid loading, specific surface area and pore volume of the catalyst decreased with the increase of alkyl chain of ionic liquid. When the alkyl chain of ionic liquid was octyl group, dodecyl group or hexadecyl group, the yield of methyl oleate was higher than 95%, and after three cycles, the yield of methyl oleate was still higher than 90%.