KF改性MgAl水滑石催化酯交换合成碳酸乙烯酯

Synthesis of ethylene carbonate by transesterification over KF modified MgAl hydrotalcite catalyst

通过简单的共沉淀法制备了MgAl水滑石(Mg3Al1-LDH)。随后通过超声法成功合成了KF负载的Mg3Al1-LDH(KF/Mg3Al1-LDH)前体,并在450℃下煅烧5h,得到一系列KF/Mg3Al1-LDO催化剂。使用X射线衍射、热重、红外光谱、N2-吸脱附、CO2-程序升温脱附对所制备的催化剂进行表征。表征结果显示样品具有典型的水滑石结构、较好的热稳定性和较高的碱强度。以KF-Mg3Al1-LDO作为催化剂用于碳酸二甲酯(DMC)和乙二醇(EG)酯交换合成碳酸乙烯酯(EC)的反应中,考察了反应工艺条件对催化性能的影响。KF/Mg3Al1-LDO催化剂表现出良好的催化性能。在酯醇摩尔比为1∶1、催化剂用量占DMC质量2%、反应温度为100℃、反应时间为4h的条件下,EC收率达到最高(54%)。催化剂可循环使用5次以上而催化活性没有显著下降。

MgAl hydrotalcite(Mg3Al1-LDH)was prepared by a simple coprecipitation method.Then KFsupported Mg3Al1-LDH(KF/Mg3Al1-LDH)was successfully synthesized by ultrasonic method and was further calcined at 450℃for 5h to obtain a series of KF/Mg3Al1-LDO catalysts.The synthesized catalysts were characterized by means of XRD,TG,FTIR,N2 adsorption-desorption and CO2-TPD.The characterization results indicated that the synthesized sample had typical hydrotalcite structure,good thermal stability and relatively high basic strength.The KF/Mg3Al1-LDO materials were employed as catalysts for the synthesis of ethylene carbonate(EC)via transesterification between dimethyl carbonate(DMC)and ethylene glycol(EG).The influences of reaction conditions on the catalytic performance have been investigated.Under the reaction conditions of molar ratio of ester to alcohol of 1∶1,2%weight percentage of catalyst in DMC,reaction temperature of 100℃,and reaction time of 4h,the highest EC yield(54%)was achieved.Furthermore,the catalyst could be reused for at least five times without significant loss of catalytic activity.