An infrared study on the MoO_3/SiO_2 catalytic system employed in toluene nitration

摘要

The 15% MoO_3/SiO_2 catalyst obtained by calcination of the (NH_4)_6Mo_7O_24 centre dot 4H_2O/SiO_2 system at various temperatures, as well as upon its use in the reaction of toluene nitration using 65 or 100% HNO_3, was studied by IR spectroscopy. The calcination process conducted at 240,300, or 550 deg C proceeds first through the formation of the Keggin structures, silicomolybdic acid, then, of molybdenum trioxide. All the molybdenum phases on the silica support obtained were found to be active in the toluene nitration process.