Preparation of MCM-41 incorporated with lacunary Keggin polyoxometalate and its catalytic performance in esterification

The ordered mesoporous MCM-41 materials incorporated with lacunary polyoxometalate were prepared via an original direct synthesis method. As the control, the samples with similar lacunary polyoxometalate loadings were also prepared by impregnation of MCM-41. The prepared samples were characterized by XRF, XRD, FT-IR, Raman spectra, HRTEM, SEM, N(2) adsorption isotherm, TG-DTA, and NH(3)-TPD technology. The results show that the lacunary polyoxometalate is better dispersed in the direct synthesized samples than in the impregnated samples, and its structure remains intact after formation of the materials. The catalytic performance of the materials was tested using the esterification of n-butanol with acetic acid. The direct synthesized samples display excellent catalytic performance and reusability, which is superior to the impregnated samples. Under the optimized conditions, the conversion of n-butanol is 89.7%, and the selectivity of butyl acetate is nearly 100%. (C) 2011 Elsevier Inc. All rights reserved.