固体碱KF/Al_2O_3的制备及其酯交换催化性能

采用浸渍法制备了KF/Al_2O_3固体碱催化剂,并应用在大豆油与甲醇的酯交换反应中,探索了催化剂制备条件和酯交换反应条件;采用SEM,XRD,TG-DTA等方法对催化剂进行了表征。实验结果表明,当KF负载量(基于Al_2O_3载体的质量)为40%时,在773 K下焙烧3 h,可制得催化活性较高KF/Al_2O_3催化剂。XRD与TG-DTA表征结果显示,KF/Al_2O_3催化剂的活性是因KF与Al_2O_3经高温焙烧产生了新的晶相K_3AlF_6。在n(甲醇):n(大豆油)=12:1、催化剂用量(基于大豆油的质量)为3%、回流状态下反应3 h,生物柴油的收率可达83.7%。

Preparation of Solid Base Catalyst KF/Al2O3 for Transesterification

A KF/Al_2O_3 solid base catalyst was prepared by an impregnation method and characterized by means of XRD,SEM and TG-DTA.The catalytic performances of the catalyst in the transesterification of soybean oil with methanol were evaluated.The optimal conditions for the preparation of the KF/Al_2O_3 catalyst were KF loading(based on the mass of Al_2O_3 support) 40%, calcination temperature 773 K and calcination time 3 h.The XRD and TG-DTA results show that a new K_3AlF_6 crystalline phase forms under the optimal conditions,which plays an important role in the form of catalytic active sites on the catalyst surface.Under the optimum conditions for the transesterification of n(methanol):n(soybean oil) 12:1,catalyst dosage(based on the mass of soybean oil) 3%and reaction time 3 h in reflux state,the yield of biodiesel can reach 83.7%.