INFRARED SPECTROSCOPIC STUDY OF THE ADSORPTION OF NITRO-COMPOUNDS ANDAMINES ON COBALT OXIDE

The adsorption of nitrobenzene on unsupported and SiO2-supported Co3O4 and a range of adsorbed reaction products of nitrobenzene are studied by infrared spectroscopy. Products observed after adsorption of nitro benzene on Co3O4 are aniline, azoxybenzene, and cyclohexylamine (reduc tion products) at lower temperatures and carbonates and cyanates (oxid ation products) at higher temperatures. One of the supported cobalt ox ides appears to be very different from the pure Co3O4, probably due to cobalt silicate formation during its synthesis. With all samples, the surface reactivity and adsorption of gases are mostly related to hydr oxyl groups, but Lewis acid sites ace also present on the surface. (C) 1994 Academic Press, Inc.