H3PW12O40/酸改性硅藻土催化剂的制备、表征及催化合成乙酸正丁酯

Preparation, characterization of acid modified diatomite supported H3PW12O40 and its catalytic performance for n-butyl acetate synthesis

以硫酸改性后的硅藻土为载体,Keggin结构磷钨酸为活性组分,通过浸渍法制备出负载型催化剂H3PW12O40/改性硅藻土,并对催化剂进行傅里叶变换红外光谱(FTIR)、X射线衍射(X RD)、扫描电镜(SEM)、X射线能谱(EDS)和N2-程序升温脱附(N 2-TPD)表征。结果表明:酸改性后硅藻土的微孔增大增多,比表面积增大。H3PW12O40均匀分布在改性硅藻土载体上,负载后磷钨酸仍保持Keggin结构。以H3PW12O40/改性硅藻土为催化剂催化乙酸和正丁醇液相合成乙酸正丁酯,通过正交试验探索优化工艺条件。在较优工艺条件下,即w(40%H3PW12O40/改性硅藻土)=1.1%(基于反应物质量),n(酸)∶n(醇)=1∶3,125℃反应2.0h,酯化率高达98.1%。催化剂重复催化使用5次,酯化率仍可达86.1%。H3PW12O40/改性硅藻土可作为催化合成乙酸正丁酯的高效催化剂,具有活性高、用量少、价格低廉、制备简单、后处理简便、无废液排放等优点。

The supported catalyst of H3PW12O40/acid modified diatomite was prepared by using the acid modified diatomite as carrier and Keggin type phosphotungstic acid as active constituents.The catalyst was characterized by FTIR,XRD,SEM,EDS and N2-TPD.The results showed that acid modification obviously increased the BET specific surface area and the pore structure of diatomite.Phosphotungstic acid kept Keggin type after distributed on the surface or inside the pore of acid modified diatomite.The synthesis of n-butyl acetate from acetic acid with n-butanol using the H3PW12O40/acid modified diatomite as catalyst was studied.The optimum reaction conditions were optimized via orthogonal tests,which was as follows:the mass percentage of 40%H3PW12O40/acid modified diatomite of 1.1%,based on the total reactants,the mole ratio of acetic acid to n-butanol of 1∶3,reaction temperature 125℃and reaction time 2.0h,under which the yield of n-butyl acetate was 98.1%.H3PW12O40/acid modified diatomite catalyst could be reused for 5 times and the yield of n-butyl acetate was still above 86.1%.The catalyst for the esterification reaction has many advantages such as easy preparation,low cost,high activity,simple posttreatment,non-corrosive to equipment and no pollution.