Synthesis of lacunary polyoxometalate encapsulated into hexagonal mesoporous silica and their catalytic performance in esterification

Abstract

The lacunary polyoxometalate (LPOM) encapsulated into the hexagonal mesoporous silica matrix materials were successfully prepared via a directly synthesis method by adjusting pH of the preparation system from 2.0 to 6.0. The materials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption–desorption measurements, scanning electron microscopy, X-ray fluorescence analysis, and high-resolution transmission electron microscopy. The results show that the samples possess an ordered pore structure with which changed from uniform ribbing-type to cobweb shape cavity along with the LPOM content increasing from 0% to 30%. The materials possess a high specific surface area of 878–626m2g−1 and a mesopore diameter of about 3.8nm. They also show an excellent catalytic performance and a good reusability for the esterification of n-butanol with acetic acid.