坡缕石负载硅钨酸催化合成乙酸正丁酯

Synthesis of n-butyl acetate catalyzed by palygorskite supported tungstosilicic acid

为减少酯化反应中常用液体催化剂带来的毒性和污染性并考虑到催化剂的可回收利用性,本文利用回流蒸发吸附法制备了坡缕石负载的十二硅钨杂多酸多相催化剂,并用红外光谱进行了表征.研究表明,12-硅钨酸与坡缕石发生相互作用且仍保持Keggin结构.将该物质作为催化剂用于乙酸正丁酯的合成,采用正交实验测定了影响酯化反应的工艺条件,反应温度115℃,醇酸的量比为n(正丁醇)∶n(乙酸)=1∶1.1,带水剂环己烷6 mL,反应时间70 min时,产率可达77.3%.催化剂稳定性实验表明载体上的活性物质仍存在部分流失.这是由于杂多阴离子部分溶解于反应介质中的缘故.

In order to make a heterogeneous catalyst which can be easily recycled from esterification system and, to some extent, diminish the toxicity and corrosion of widely used liquid catalysts simultaneously, acid Palygorskite supported tungstosilicic acid was prepared by adsorption method through reflux and evaporation, and was characterized by FTIR spectroscopy. The FTIR spectra shows that interaction occurs between carrier and 12 - tungstocilicic acid which maintains the Keggin type structure. The synthesis of n - butyl acetate was catalyzed by this kind of catalyst and the reaction conditions were measured by orthogonal experimental design. Under the reaction conditions that molar ratio of n - butanol to acetic acid is 1 ： 1. 1, volume of cyclohexane acting as water carrier is selected as 6 ml, reaction time is 70 min and temperature is at 115℃ , the yield could reach 77.3%. The catalyst recycling result has shown that a deactivation occurs, which due to the redissolution of the polyanion in the reaction medium.