硅藻土负载Dawson结构磷钨酸催化合成对羟基苯甲酸正丁酯

以硅藻土为载体,采用浸渍法制备了H6P2W18O62/硅藻土催化剂,并采用FTIR,EDS,XRD,SEM等手段对催化剂进行了表征;以对羟基苯甲酸正丁酯的合成反应为探针,考察了H6P2W18O62/硅藻土催化剂的性能;通过单因次和正交实验研究了H6P2W18O62负载量、催化剂用量、正丁醇与对羟基苯甲酸的摩尔比(醇酸比)、反应时间和反应温度对酯化反应的影响。确定了优化工艺条件为:H6P2W18O62负载量为40%(基于硅藻土的质量)、催化剂用量0.5 g(占反应体系总质量的2.8%)、醇酸比3、反应时间3.0 h、反应温度125℃。在此条件下,对羟基苯甲酸正丁酯的平均收率可达90.8%;催化重复使用5次,对羟基苯甲酸正丁酯收率仍可达65.6%。

Synthesis of Butyl p-Hydroxybenzoate over Diatomite Supported Phosphotungstic Acid with Dawson Structure

Diatomite supported phosphotungstic acids with Dawson structure were prepared by an impregnation method and used as catalysts for the synthesis of butyl p-hydroxybenzoate by the esterification of p-hydroxy benzoic acid with n-butyl alcohol.The effects of the catalyst preparation and reaction conditions on the esterification were investigated through orthogonal experiments.The yield of butyl p-hydroxybenzoate could reach 90.8% under the optimum conditions of phosphotungstic acid loading on the diatomite support 40%(based on the diatomite mass),mass ratio of the catalyst to the total reactants 2.8%,molar ratio of n-butyl alcohol to p-hydroxy benzoic acid 3,reaction time 3.0 h and reaction temperature 125 ℃.The catalyst could be reused for 5 times and the yield of butyl p-hydroxybenzoate was still kept at 65.6%.