负载型杂多酸催化2-丁烯与醋酸直接酯化

Esterification of 2-Butylene with Acetic Acid Catalyzed by Silica-Supported Heteropolyacid

采用加热回流法制备了SiO2负载磷钨酸催化剂,并用于催化2-丁烯与醋酸的直接酯化反应;考察了反应条件对酯化反应的影响;用电导率法测定了催化剂的活性组分磷钨酸在产物中的溶脱量;采用傅里叶变换红外光谱、吡啶吸附红外光谱、BET比表面积测定等方法对失活催化剂进行了表征并探讨了催化剂的失活原因。实验结果表明,酯化反应的优化条件为:反应温度110℃、反应压力1.5MPa、n(2-丁烯):n(醋酸)=2、反应时间9h、催化剂用量m(磷钨酸):m(醋酸)=0.03、水用量V(水):V(醋酸)=0.02,在此条件下,醋酸的转化率为33.5%,醋酸仲丁酯的选择性为92.7%;催化剂重复使用3次后失活,磷钨酸的最大溶脱量约54%,失活催化剂中磷钨酸的Keggin结构被破坏,L酸酸量下降,B酸完全消失。

Silica- supported phosphotungstic acid catalyst was prepared by heating -refluxing method and its catalytic performance in esterification of 2 -butylene and acetic acid was tested. Optimal operating conditions are： reaction temperature 110 ℃, reaction pressure 1.5 MPa, n（2 - butylene） ： n （acetic acid） 2, V（water） ： V （acetic acid） 0.02, reaction time 9 h and m（ tungstophosphoric acid） ： m（ acetic acid） 0. 03. Under above conditions conversion of acetic acid is 33.5% and selectivity to butyl acetate is 92.7%. The catalysts deactivated after being reused for three times and reason of deactivation was further analyzed. The deactivated catalysts were characterized by means of FTIR, Py - IR and BET. The amount of phosphotungstic acid dissolved in the products was measured. The results show that amount of phosphotungstic acid dissolved, to one＇ s surprise, reaches up to about 54%. The Keggin structure of phosphotungstic acid in deactivated catalyst is destroyed. The amount of Lewis acid diminishes and Bronsted acid disappears.