TRANSIENT ISOTOPIC TRACING OF NICKEL-CATALYST DEACTIVATION IN A PLUG-FLOW REACTOR

Deactivation of Raney nickel is studied using the methanation rate dat a in a plug-flow reactor. It is shown that a model consisting of a con stant and a monoexponential term describes the deactivation rate data very well suggesting that the catalytic activity of nickel is controll ed by two components. One component seems to show a steady catalytic a ctivity where the activity of the other component appears to decline e xponentially. Transient tracing of the methanation on Raney nickel usi ng (CO)-C-13 indicates that these correspond to two forms of intermedi ates adsorbed on two distinct catalyst sites. These findings are suppo rted by rigorous statistical analyses of the correlation between model parameters and the goodness of the fit of data to the model.