醋酸甲酯在Cs_(1.5)PW/SiO_2催化剂上的水解反应

通过改变阳离子的种类与配比,制备了一系列SiO2负载的磷钨酸盐催化剂,考察了制备方法对催化剂性能的影响,采用傅里叶变换红外光谱、X射线衍射、X射线荧光光谱、环境扫描电子显微镜等方法对催化剂进行了表征,并考察了该系列催化剂对醋酸甲酯水解反应的活性。实验结果表明,Cs1.5PW/SiO2催化剂的活性最好,当Cs1.5PW负载量(质量分数)为30%时,Cs1.5PW的Keggin结构保持完好,没有硅钨酸阴离子形成,Cs1.5PW在SiO2载体上高度分散;在反应温度55℃、反应时间2h的条件下,醋酸甲酯的转化率为35.79%,约为均相磷钨酸催化剂的1.3倍。该催化剂重复使用4次后,醋酸甲酯的转化率稳定在25%;80℃下反应2h,与NKC-9磺酸树脂催化剂相比,醋酸甲酯的转化率提高了5.17%。

Hydrolysis of Methyl Acetate on Cs1.5PW/SiO2 Catalyst

A series of SiO_2 supported tungstophosphoric acidic salt catalysts were prepared by different methods.Influence of preparation conditions such as cation kinds,mole ratio of metallic salt to tungstophosphoric acid,preparation method and tungstophosphoric acidic salt loadings were discussed.The catalytic properties in hydrolysis of methyl acetate were examined.The catalysts were characterized by means of FTIR,XRD,X-ray fluorescence spectroscopy(XRF) and ESEM.Cesium tungstophosphate shows best catalytic activity in the reaction.The cesium salt disperses evenly on silica support loaded with 30%(mass fraction) Cs_1.5PW/SiO_2.The Keggin structure of tungstophosphoric acid keeps intact.No SiW_12O4-_40 anion is observed.The conversion of methyl acetate reach 35.79% at 55 ℃ for 2 h.It is 1.3 times more active than mere tungstophosphoric acid powder.The conversion in hydrolysis is steady at 25% after reuse of 4 times.Methyl acetate conversion was 5.17% higher using the prepared Cesium tungstophosphate catalyst than that using NKC-9 sulfonic acid resinas catalyst at 80 ℃ for 2 h.