Hybrids of [C4mim]3+xPMo12−xVxO40: A new catalyst for oxidation of benzyl alcohol to benzaldehyde in water with greatly improved performances

A series of hybrid materials ([C4mim]3+xPMo12−xVxO40, x = 0, 1, 2) based on V-substituted phosphomolybdic acid H3+xPMo12−xVxO40 (x = 0, 1, 2) and ionic liquid 1-butyl-3-methyl imidazolium bromide ([C4mim]Br) have been prepared by anion-exchange method. The samples were well characterized by X-ray diffraction, Fourier transform infrared spectrophotometry and UV–Vis diffuse reflectance spectra analysis. The catalytic performances of the samples were tested in oxidation of benzyl alcohol to produce benzaldehyde using H2O2 as oxidant in water. The results have shown that the hybrids [C4mim]3+xPMo12−xVxO40 exhibit much higher catalytic properties than both the corresponding moieties. Especially, under the optimized conditions, 34% of benzyl alcohol conversion and 99% of selectivity for benzaldehyde have been obtained in the case of [C4mim]4PMo11VO40. The sample also exhibits good reusability and has been reused five runs without much decrease in conversion and selectivity.

Graphical abstractThe polyoxometalate/ionic liquid hybrids with greatly enhanced catalytic performances have been synthesized. Benzyl alcohol can be almost quantitatively converted to benzaldehyde. The catalytic system is green and effective.Figure optionsDownload full-size imageDownload as PowerPoint slide