K_2CO_3/MgO催化合成碳酸乙丙酯

以K_2CO_3/MgO为固体碱催化剂,正丙醇与碳酸二乙酯(DEC)经液相酯交换合成了碳酸乙丙酯(EPC);用X射线衍射和CO_2程序升温脱附的方法对催化剂进行了表征。表征结果显示,随K_2CO_3负载量的增加,MgO载体的特征衍射峰强度减弱,在K_2CO_3负载量较高时有明显的K_2O晶相出现;K_2CO_3/MgO催化剂上的弱碱性位可能是催化该反应的活性中心。同时考察了K_2CO_3负载量、催化剂用量、反应时间和原料配比对酯交换反应的影响。实验结果表明,K_2CO_3负载量为20%(相对于催化剂的质量分数)的K_2CO_3/MgO催化剂对该反应有较好的催化性能;适宜的反应条件为:催化剂用量为反应物质量的1.00%、反应温度403 K、反应时间4 h、n(DEC):n(正丙醇)=1.0:1.5;在此条件下,DEC的转化率为62.32%,EPC的选择性为83.29%,EPC的收率为51.89%。

Synthesis of Ethyl Propyl Carbonate by Transesterification of Diethyl Carbonate with n-Propanol over K_2CO_3/MgO Catalyst

Ethyl propyl carbonate was synthesized by transesterification of diethyl carbonate(DEC) with n-propanol in liquid phase over K_2CO_3/MgO catalyst.K_2CO_3/MgO catalysts were characterized by means of XRD and CO_2-TPD.Results of XRD indicated that the intensity of peaks ascribed to MgO decreased obviously with increasing of K_2CO_3 amount and the peaks of K_2O were also detected on catalysts loaded with substantial amount of K_2CO_3.Results of CO_2-TPD revealed that weak basic sites of K_2CO_3/MgO might be the active sites for transesterification of DEC with n-propanol.Effects of K_2CO_3 loading amount,catalyst dosage,reaction time and ratio of reactants on transesterification were investigated.The highest catalytic activity corresponded to catalyst loaded with 20%(based on mass of catalyst) of K_2CO_3 on MgO.Under optimal conditions: catalysts dosage 1.00%(based on mass of reactants),reaction temperature 403 K,time 4 h and n(DEC):n(n-propanol) 1.0:1.5,conversion of DEC was 63.32%,selectivity and yield of ethyl propyl carbonate were 83.29% and 51.89%,respectively.