硅胶负载磷钨酸催化正丁醇和乙酸液相酯化反应

Liquid-Phase Esterification of n -Butanol with Acetic Acid on Silica Gel Supported Phosphotungstic Acid Catalysts

以硅胶为载体,用浸渍法制备了一系列不同负载量的磷钨酸催化剂,通过X射线衍射、低温N2物理吸附、程序升温氨脱附以及Hammett指示剂法表征了催化剂的物化性质,并考察了催化剂在乙酸与正丁醇液相酯化反应中的催化性能。结果表明,通过控制杂多酸负载量,可有效调整催化剂的表面性质、酸性及酯化反应性能;酯化反应结果与催化剂酸量、比表面积及磷钨酸在载体表面分散状况有直接关系。磷钨酸负载量为40%时,反应物的转化率及酯的产率均明显高于纯磷钨酸催化剂的结果。在反应温度为395K、催化剂在反应体系中的质量分数为3.5%、反应时间为120min的条件下,正丁醇转化率达89.8%,乙酸丁酯选择性为100%。

A series of phosphotungstic acid(PW)catalysts supported on silica gel with various PW loadings were prepared by impregnation method, and characterized by means of X - ray diffraction, physical adsorption of nitrogen, temperature programmed desorption of ammonia,and Hammett indicators. Their catalytic activity was determined in esterification of n -butanol with acetic acid in a slurry reactor under atmospheric pressure. Physical properties, acidity and catalytic behavior of catalysts could be adjusted by controlling PW loadings. Moreover, catalytic activity related closely with catalyst surface area, acid amount and dispersion of PW on the surface of the support. Activation temperature for the catalyst did not substantially influence its catalytic activity as expected. For the catalyst with a PW loading of 40 % , the optimal reaction conditions were: reaction temperature 395 K, reaction time 120 min,and catalyst mass fraction 3.5% in reaction medium. In this case,a n - butanol conversion of 89.8% with a selectivity of n -butyl acetate of 100% could be achieved.