INSITU DRIFTS STUDY OF ADSORBED SPECIES IN THE HYDROGENATION OF CARBON OXIDES

The hydrogenation of carbon oxides over rhodium supported (alumina, Sm- and Lu-promoted alumina) catalysts has been studied in both, a fixed-bed flow reactor and by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), using a catalytic cell that allows the collection of the vibrational spectra of the adsorbed species in the flow of reactants at the actual reaction conditions. Product distributions and activation energies obtained by these two methods are in fairly good agreement. From the obtained data, a model in which adsorbed formate acts as intermediate in the methanation reaction has been developed, ascribing the differences in activity to the presence of adsorbed carbonyls at the metal sites.