磺化MCM-41介孔固体酸的合成、表征及其催化乙酰丙酸乙酯化性能

以硅酸乙酯为硅源、十六烷基溴化铵为模板剂,室温常压下便捷地合成了MCM-41介孔分子筛,进而以硫酸为磺化剂,不同水热条件下制得系列磺化介孔固体酸MCM-41-SO3H.利用TG、XRD、FT-IR、TEM-EDX等手段对所得材料进行了表征.采用碱滴定法测定其酸密度,并且以乙酰丙酸乙酯化反应为探针反应,评价其催化性能.结果表明,尽管水热磺化处理在一定程度上降低了MCM-41的介孔规整性,所制备的MCM-41-SO3H介孔固体酸仍较好地保持了MCM-41的介孔结构;水热时间和温度影响其酸密度,进而影响催化活性,其中磺化温度180℃、磺化时间21h制得的催化剂活性最高,乙酰丙酸转化率达到74.4%,并显示出较好的循环稳定性能.

Synthesis,Characterization and Catalytic Performance of Sulfonated MCM-41 Mesoporous Solid Acid for Levulinic Acid Esterification with Ethanol

Mesoporous molecular sieves MCM-41 was facilely synthesized at room temperature under normal pressure.Then,it was used to hydrothermally prepare a series of sulfonated MCM-41 mesoporous solid acids with sulfuric acid as sulfonating agent.The samples were characterized by TG,XRD,FT-IR,and TEM-EDX.The acid density was measured by base titration.Furthermore,their catalytic properties were evaluated with the synthesis of ethyl levulinate as a probe reaction.The results showed that the resulting MCM-41-SO3 H catalysts maintained the mesoporous structure of MCM-41,although the hydrothermal process reduced the mesoporous regularity to a certain extent.Meanwhile,the hydrothermal time and temperature affected their acid density,which in turn affected the catalytic activity.The catalyst hydrothermally prepared at 180 ℃ for 21 hexhibited the highest catalytic activity,and the corresponding conversion of levulinic acid as high as 74.4%.In addition,the resulting mesoporous solid acid also displayed satisfactory cyclic stability.