硅胶负载磷钨酸铯催化合成对甲氧基苯乙酮

采用两步浸渍法制备了硅胶负载磷钨酸铯催化剂Cs2.5H0.5PW12O40/SiO2,将其用于催化合成对甲氧基苯乙酮(p-MOAP)。采用X射线衍射、傅里叶变换红外光谱和NH3程序升温脱附等技术对Cs2.5H0.5PW12O40/SiO2催化剂进行了表征,考察了Cs2.5H0.5PW12O40负载量、催化剂用量、反应物配比、反应温度、反应时间等对p-MOAP合成反应的影响。表征结果显示,Cs2.5H0.5PW12O40和Cs2.5H0.5PW12O40/SiO2催化剂保持了H3PW12O40的Keggin结构,且Cs2.5H0.5PW12O40/SiO2催化剂中Cs2.5H0.5PW12O40主要聚集在载体表面。实验结果表明,优化的合成p-MOAP工艺条件为:Cs2.5H0.5PW12O40负载量为30%(质量分数)的Cs2.5H0.5PW12O40/SiO2催化剂用量为4%(占总物料的质量分数)、苯甲醚与乙酸酐的摩尔比为10、反应温度100℃、反应时间120min。在此条件下,使用新鲜催化剂时,p-MOAP的收率达到83.4%,选择性达到96.1%。

Synthesis of p-Methoxyacetophenone Catalyzed by Silica Supported Cesium-Substituted Dodecatungstophosphate

SiO2-supported cesium-substituted dodecatungstophosphate(Cs2.5H0.5PW12O40/SiO2) catalyst for synthesis of p-methoxyacetophenone(p-MOAP) from anisole(AN) and acetic anhydride(AA) were prepared by two step impregnations.The Cs2.5H0.5PW12O40/SiO2 catalyst was characterized by means of XRD,FTIR and NH3-TPD.Effects of Cs2.5H0.5PW12O40 loading amount on the catalyst,and mole ratio of AN to AA,reaction temperature and reaction time on yield and selectivity to p-MOAP were investigated.In both Cs2.5H0.5PW12O40 and Cs2.5H0.5PW12O40/SiO2,the primary Keggin structure of dodecatungstophosphate was maintained.In Cs2.5H0.5PW12O40/SiO2 catalyst,the dodecatungstophosphate mainly accumulated on surface of SiO2 support.Under optimum reaction conditions for synthesis of p-MOAP:30%(w)Cs2.5H0.5PW12O40/SiO2 catalyst dosage 4%(mass fraction on total mass of reaction system),mole ratio of AN to AA 10,reaction temperature 100 ℃ and reaction time 120 min,yield and selectivity to p-MOAP were 83.4% and 96.1%,respectively.