Dawson结构磷钨酸银催化剂的制备、表征及其催化合成乙酸正丁酯

Preparation,Characterization and Catalytic Application of Ag_3H_3P_2W_(18)O_(62)·nH_2O for the Synthesis of n-Butyl Acetate

采用沉淀法制备了磷钨酸银(Ag3H3P2W18O62·nH2O)催化剂,通过FT-IR、UV-Vis、XRD、EDX、SEM、NH3-TPD对其进行了表征,并用于催化乙酸与正丁醇酯化合成乙酸正丁酯反应。结果表明,合成的Ag3H3P2W18O62·nH2O具有Dawson结构,呈微球状,粒子大小在200300nm范围;同时具有Brnsted酸和Lewis酸的弱酸中心、强酸中心和超强酸中心,可发挥Brnsted酸性和Lewis酸性催化剂的双重作用,在乙酸和正丁醇的酯化反应中具有良好的催化性能。在优化反应条件下,即醇/酸摩尔比2.0、反应温度120℃、催化剂质量分数0.48%（以反应物质量计）、反应时间2.0h条件下,酯化率可达97.0%。催化剂易回收重复使用,重复使用5次,酯化率仍可保持在86.3%。

Ag_3H_3P_2W_(18)O_(62)·nH_2O catalyst was prepared by homogeneous precipitation method,and characterized by FT-IR,UV-Vis,XRD,EDX,SEM and NH3-TPD.The catalyst was applied in the catalytic synthesis of n-butyl acetate with acetic acid and n-butanol.Experimental results showed that the self-prepared Ag_3H_3P_2W_(18)O_(62)·nH_2O catalyst kept primary Dawson structure and appeared in the shape of spherulite-structure particles with the size between 200 and 300 nm.Ag_3H_3P_2W_(18)O_(62)·nH_2O possessed weak acid sites,strong acid sites and super acid sites of Brnsted and Lewis acidity.With the dual functions of Brnsted catalyst and Lewis catalyst,the selfprepared Ag_3H_3P_2W_(18)O_(62)·nH_2O has good catalytic performance for the esterification of acetic acid and n-butanol.Under the optimal reaction conditions of reaction time 2.0h,reaction temperature120℃,the molar ratio of butanol to acetic acid 2.0and the mass fraction 0.48% of catalyst over reactants,the highest esterification conversion was 97.0%.Ag_3H_3P_2W_(18)O_(62)·nH_2O catalyst could be reused for 5times with the esterification conversion of 86.3%.