A facile method for synthesis of Keggin-type cesium salt of iron substituted lacunary phosphotungstate supported on MCM-41 and study of its extraordinary catalytic activity

A novel catalyst, Keggin-type Cs salt of Fe substituted mono lacunary phosphotungstate supported MCM-41 was synthesized from H3PW12O40, FeCl2 and Cs2CO3 and characterized by different techniques like X-ray diffraction, UV–vis diffused reflectance spectroscopy (UV–vis DRS), nitrogen adsorption–desorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectra and Fourier-Transform Infrared Spectroscopy (FT-IR). Diffused reflectance spectra and FT-IR studies confirmed the undegraded Keggin structure of the lacunary salt after supporting it on MCM-41. The material showed its amazing catalytic activity toward two different types of reactions. Among various samples prepared, 50 wt% Fe substituted lacunary salt supported MCM-41 showed remarkable catalytic performances. In acid catalyzed bromination of phenol, it showed 95% conversion obtaining p-bromophenol with 99% selectivity and in case of oxidation of trans-stilbene using hydrogen peroxide oxidant, the same catalyst gave 52% conversion with 99% trans-stilbene oxide selectivity.