酯化催化剂Ga_2O_3/SiO_2的研制及其催化合成丁酸辛酯

Preparation of Esterification Catalyst Ga_2O_3/SiO_2 for Synthesis of Octyl Butyrate

制备了以Ga2O3为活性组分的硅胶负载氧化物型酯化催化剂Ga2O3/SiO2,采用FTIR技术对催化剂进行了表征;并将其用于催化正丁酸与正辛醇酯化反应合成丁酸辛酯,考察了催化剂制备条件(Ga2O3负载量和焙烧温度)、催化剂用量、n(正辛醇)∶n(正丁酸)、反应时间对酯化率的影响,还考察了催化剂的重复使用性能。实验结果表明,适宜的催化剂制备条件为:Ga2O3负载量(w)20%,500℃下焙烧2h。该催化剂催化合成丁酸辛酯的适宜反应条件为:正丁酸0.2mol,n(正辛醇)∶n(正丁酸)=1.8、催化剂用量(占总反应物的质量分数)1.03%、环己烷10mL、反应时间120min,在此条件下酯化率为96.5%。催化剂重复使用3次后,酯化率仍可达94.3%。Ga2O3/SiO2的热稳定性明显优于硫酸促进型酯化催化剂SO42-/SiO2和SO24-/SiO2-Ga2O3。

A novel silica supported oxide catalyst Ga2O3/SiO2 for esterification was prepared and characterized by means of FTIR. The catalyst was used in esterification of n-octanol and n-butyric acid to octyl butyrate. The effects of the catalyst preparation conditions （Ga2 O3 loading and the catalyst calcination temperature）, catalyst dosage, mole ratio of n-octanol to n-butyric acid, reaction time and the catalyst reuse on the esterification rate were investigated. These results indicated that under the suitable conditions of Ga203 loading（w） 20%, calcination temperature 500℃ and calcination time 2 h for the catalyst preparation, and n-butyric acid 0.2 mol, mole ratio of n-octanol to n-butyric acid 1.8, the catalyst mass fraction in the reaction system 1.03%, water entrainer cyclohexane 10 mL and reaction time 120 min for the esterification reaction, the esterification rate could reach 96.5%. The catalyst exhibited high activity up to 94.3 % after being reused three times. Furthermore, its thermal stability obviously exceeded the esterification catalysts SO2-/SiO2 and SO4 2--/SiO2-Ga2O3.