SiO_2负载硫酸锆固体酸催化酯化反应

采用溶胶-凝胶法制备了SiO2载体,同时采用浸渍法制备了SiO2负载Zr(SO4)2固体酸催化剂(Zr(SO4)2/SiO2),并将其用于催化油酸与乙醇进行酯化反应;考察了催化剂焙烧温度、Zr(SO4)2负载量、n(乙醇)∶n(油酸)、催化剂用量和反应时间对酯化反应的影响。实验结果表明,与Zr(SO4)2催化剂相比,Zr(SO4)2/SiO2催化剂在油酸与乙醇的酯化反应中具有较高的活性。最佳反应条件为:以焙烧温度为250℃制得的Zr(SO4)2负载量为25%的Zr(SO4)2/SiO2为催化剂,n(乙醇)∶n(油酸)=6,催化剂占油酸的质量分数为5.0%,反应时间6h。在此条件下,油酸乙酯的收率可达94.8%。Zr(SO4)2/SiO2催化剂的制备方法简单、活性高,产品收率高,后处理简便,无三废污染,符合节能环保、绿色催化的发展趋势。

Esterification on Silica Supported Zirconium Sulfate Solid Acid Catalyst

Silica supported zirconium sulfate(Zr(SO4)2/SiO2) solid acid catalyst for esterification was prepared by impregnation and the support was prepared by sol-gel method.Activities of catalyst in esterification of oleic acid with ethanol were evaluated.Effects of calcination temperature of catalyst,mass fraction of Zr(SO4)2 in the catalyst,mole ratio of ethanol to oleic acid,Zr(SO4)2/SiO2 catalyst dosage and reaction time on the esterification were discussed in detail.Supported Zr(SO4)2/SiO2 was more active than the unsupported Zr(SO4)2 catalyst.Under optimal esterification conditions: calcination temperature of catalyst 250 ℃,loading amount of Zr(SO4)2(based on total mass of catalyst) 25%,mole ratio of ethanol to oleic acid 6,mass fraction of Zr(SO4)/SiO2 in oleic acid 5.0% and reaction time 6 h,the yield of ethyl oleate is 94.8%.The Zr(SO4)2/SiO2 catalyst was simple in preparation,high in catalytic activity,convenient in separation after reaction and no waste releasing.