硅烷化改性凹凸棒石负载磷钨钼杂多酸催化合成乙酸正戊酯

以杂多酸H3PW6Mo6O40(PWMo)为活性组分,硅烷化改性的凹凸棒石(KH550-Pa)为载体,采用浸渍法制备了负载型PWMo/KH550-Pa催化剂,利用FTIR和XRD等方法对其结构进行了表征,并考察了其在乙酸正戊酯合成反应中的催化性能。实验结果表明,PWMo/KH550-Pa催化剂中的PWMo仍保持Keggin结构,并以离子对形式均匀、随机地分布在载体的表面及孔径内;在乙酸正戊酯的合成反应中,杂多酸PWMo适宜的负载量为30%(w);催化剂用量、反应温度、反应时间、n(乙酸)∶n(正戊醇)对乙酸正戊酯的选择性影响不大;以30%PWMo/KH550-Pa为催化剂的适宜反应条件为:催化剂用量0.1 g、正戊醇0.045 mol、n(乙酸)∶n(正戊醇)=4∶1、125℃、2.5 h,在此条件下正戊醇的转化率为92.34%,乙酸正戊酯的收率可达91.70%。

Preparation of n-Amyl Acetate over Silylated-Attapulgite Supported 12-Heteropolyacid of Molybdenum and Tungsten Catalyst

A supported heteropoly acid catalyst PWMo/KH550-Pa was prepared by an impregnation method with H3PW6Mo6O40(PWMo) as the active component and silylated-attapulgite(KH550-Pa) as the support.The structure of the catalyst was characterized by means of FTIR and XRD,and its catalytic performance in the synthesis of n-amyl acetate from n-amyl alcohol and acetic acid was investigated.The results show that PWMo immobilized on KH550-Pa remains a Keggin structure with uniform and random distribution in the form of ion-pairs on the support.In the synthetic reaction,the influences of catalyst dosage,reaction temperature,reaction time and molar ratio of alcohol to acid on the selectivity to n-amyl acetate can be neglected.Under the optimized conditions of PWMo loading 30%(w),PWMo/KH550-Pa dosage 0.1 g,n-amyl alcohol 0.045 mol,n(acetic acid)∶n(n-amyl alcohol) 4∶1,125 ℃ and 2.5 h,conversion of n-amyl alcohol and yield of n-amyl acetate reached 92.34% and 91.70%,respectively.