Liquid phase nitration of benzene over supported ammonium salt of 12-molybdophosphoric acid catalysts prepared by sol-gel method.

A mild and clean liquid nitration of benzene with 65% nitric acid as nitrating agent over silica supported ammonium salt of 12-molybdophosphoric acid catalysts has been investigated. These catalysts with different loadings were prepared by sol-gel method and characterized by X-ray diffraction (XRD) and FTIR spectra. The acidity of these catalysts was measured by the potentiometric titration method. The XRD and IR analysis revealed that supported catalysts possess the Keggin structure which is similar to 12-molybdophosphoric acid. And it can be found that the supported catalysts had high nitration reaction catalytic activity and selectivity over nitrobenzene. The effects of various parameters such as nitric acid/benzene volume ratio, temperature and time of reaction have also been systematically studied.