Selective oxidation of benzene to phenol with N2O by unsupported and supported FePO4 catalysts Original Research Article

The gas-phase selective oxidation of benzene to phenol with N2O, catalyzed by unsupported and supported FePO4 over oxides such as silica, alumina, zirconia, and titania was studied. Only the quartz-phase crystalline FePO4 and silica-supported FePO4 exhibited catalytic activity in the reaction. For the silica-supported FePO4 catalyst with the loading content of 5 wt.%, the conversion of benzene and the selectivity to phenol reached 7 and 90%, respectively. The results of X-ray diffraction characterization confirmed that the supports affected the structure of FePO4 on their surfaces and that quartz-phase FePO4 formed on the silica surface, while X-ray amorphous FePO4 formed on the other oxides’ surfaces. The active center of the FePO4 catalysts in such selective oxidation was proposed to be the tetrahedral-coordinated Fe in the quartz-phase FePO4.