Adsorption and catalytic reactions of acetonitrile and acetonitrile-oxygen mixture on TiO2-supported rhodium catalysts

The adsorption and surface reactions of acetonitrile and acetonitrile-oxygen gas mixture were studied on TiO2-supported Rh catalysts at 300-673 K. FTIR spectra show different kinds of molecularly adsorbed CH3CN; acetonitrile can be bonded to weak Lewis acid sites (2295 cm(-1)), to strong Lewis acid sites (2319 cm(-1)), to very strong Lewis acid centres (2347 cm(-1)) of titania; it can be coordinated linearly through the lone electron pair of the N atom on Rh sites (2193 cm(-1)) and 172 (C,N) CH3CN species can be formed on Rh particles (1691-1708 cm(-1)). CH3CN dissociates on Rh sites, the resulting CN(a) can be oxidized into NCO surface species. CN(a) can be dissociated only on Rh particles into N-(a) and C-(a). The hydrogenation of N-(a) resulted in the appearance of NH3 among the gaseous products from Rh/TiO2 catalysts. The formation of other products (CH3NH2, H-2, CO2, CH4, C2H4 and CO) was demonstrated and discussed. (c) 2006 Elsevier B.V. All rights reserved.