SnO2负载硅钨酸催化制备月桂酸单甘酯

Preparation of Monoglyceride Laurate Catalyzed by Silicotungstic Acid Supported on SnO2

摘要:

本文合成了系列金属氧化物负载硅钨酸催化剂，并利用FTIR，XRD，TGA-DTG，BET及固态31P MAS NMR技术对催化剂结构、稳定性及酸性进行表征，同时考察了金属氧化物负载硅钨酸催化剂在月桂酸单甘酯（GML）制备中的催化性能。结果表明，20HSiW/SnO2催化剂显示较好的催化性能，催化剂较强的Br?nsted酸性及硅钨酸（Br?nsted）与载体（Lewis）间的酸性协同效应，使其在GML的制备中具有良好的催化性能。以20HSiW/SnO2为催化剂，在甘油/月桂酸物质的量比5:1，催化剂用量为月桂酸质量的7%，反应时间3h，反应温度423K条件下，GML产率为78.9%；20HSiW/SnO2催化剂显示较好的重复使用性能，经5次循环利用后，GML的产率为73.6%；动力学研究表明，20HSiW/SnO2催化制备GML反应活化能为33.02 kJ/mol。

Abstract:

A series of metal oxide supported silicotungstic acid catalysts have been successfully synthesized through impregnation method. The catalysts so fabricated of the structure, stability and acidity were characterized by various physicochemical techniques such as FTIR, XRD, TGA-DTG, BET, and 31P MAS NMR and their catalytic performances during the preparation of monoglyceride laurate (GML) were assessed. The results showed that 20HSiW/SnO2 catalyst exhibited the superior catalytic performance in the preparation of GML owing to strong Br?nsted acidity and Br?nsted-Lewis acid synergy for supported catalyst. A maximum GML yield of 78.9% was achieved for the 20HSiW/SnO2 catalyst under the optimal conditions: molar ratio of glycerol (GL) to lauric acid (LA) was 5:1, the mass fraction of 20HSiW/SnO2 catalyst was 7% (based on LA), the reaction time was 3 h, and the reaction temperature was 423 K. The yield of GML could still reach 73.6% after 20HSiW/SnO2 catalyst was reused 5 times, indicating that this catalyst had excellent durability. Further kinetic studies confirmed that the esterification of GL with LA to GML with an activation energy of 33.02 kJ/mol.