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 η2 (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, H2, CO2, CH4, C2H4 and CO) was demonstrated and discussed.