Methanation on Rh surfaces at low pressure and low temperature: A pulsed-laser imaging atom-probe study

Abstract

We have successfully detected methanation on Rh surfaces at low pressure (∼10 −8 Torr) and low temperature (150 K) using pulsed-laser imaging atom-probe. Thus it is possible to observe directly the reaction intermediates in a time-of-flight mass spectrum and study the atomic steps of such reaction. We find direct evidence of dissociative chemisorption of CO on Rh surfaces and show that under the conditions of our experiment, a dissociative mechanism is responsible for methanation on Rh surfaces. We have also observed an oscillation in signal intensity of CO + and that of methanation products with a time period of ∼ 8 s under the conditions of that experiment.