THERMODESORPTIONS AND THERMOREACTIONS WIT H HYDROGEN OF CARBON-MONOXIDE AFTER ITS CHEMISORPTION ON A NICKEL-CATALYST .2. STRUCTURAL SENSITIVITY OF THE MATHANATION

Interrupted TPSR (Temperature Programmed Surface Reaction) followed by TPD (Temperature Programmed Desorption) (or, reversely, interrupted T PD followed by TPSR) show that the various CO adspecies do not react e qually fast with H-2 but the structural sensitivity remains moderate s ince a single CH4 peak is displayed in the TPSR spectrum. Compensating effects are postulated in order to explain why the methanation reacti on displays a moderate structure sensitivity only, in contrast with th e strong structure sensivity of the CO chemisorption.