磷酸钛固载磷钨酸非均相催化合成异戊酸己酯

通过在300℃下焙烧2h制备了磷酸钛固载15%磷钨酸H3PW12O40(简记为HPW)非均相酯化催化剂HPW/Ti3(PO4)4;采用红外光谱仪分析了催化剂的结构;基于异戊酸与正己醇的酯化反应考察了催化剂用量、n(正己醇)∶n(异戊酸)、反应时间、带水剂种类和催化剂重复使用性能等因素对酯化率的影响.结果表明,该催化剂催化合成异戊酸己酯的适宜反应条件为:0.2mol异戊酸,催化剂用量0.6g,n(正己醇)∶n(异戊酸)=1.6∶1,反应时间4.5h,环己烷10mL;相应的酯化率达95.1%.与此同时,该催化剂循环利用6次后酯化率不低于84%.

Synthesis of hexyl isovalerate under heterogeneous catalysis by titanium phosphate-supported phosphotungstic acid

A heterogeneous esterification catalyst, titanium phosphate-supported phosphotung- stic acid （denoted as HPW） with an HPW content of 15% （mass fraction）, was prepared by clacination at 300 ℃ for 2.0 h. The structure of as-synthesized HPW/Ti3 （PO4）4 catalyst was analyzed by means of infrared spectrometry. Moreover, the effects of catalyst dosage, molar ratio of alcohol to acid, reaction time, deaquation reagents and reusability of the catalyst on the esterification rate were investigated in relation to the esterification reaction of isopentanoic acid with n-hexanol. Results indicate that as-synthesized heterogeneous catalyst can be well used to catalytically synthesize hexyl isovalerate at an isovaleric acid dosage of 0.2 mol, an alcohol to acid molar ratio of 1.6 ： 1, a catalyst dosage of 0.6 g, a cyclohexane dosage of 10 mL, and a reaction time of 4. 5 h. Corresponding esterification rate is as much as 95. 1%. Besides, the catalyst retains an esterification rate of above 84 % after it is recycled for six cycles.