Mechanism of N2O decomposition over a Rh black catalyst studied by a tracer method - The reaction of N2O with O-18(a)

N2O decomposition on an unsupported Rh catalyst has been studied using trac er technique in order to reveal the reaction mechanism. (N2O)-O-16 was puls ed onto O-18/oxidized Rh catalyst at 220 degreesC and desorbed O-2 molecule s (m/e = 32, 34, 36) were monitored by means of mass spectrometer. The O-18 fraction in the desorbed dioxygen was the same value as that on the surfac e oxygen. The result shows that the O-2 molecules desorb via Langmuir-Hinsh elwood mechanism, i.e., the desorption of dioxygen through the recombinatio n of adsorbed oxygen. On the other hand, TPD measurements in He showed that desorption of oxygen from the Rh black catalyst occurred at the higher tem peratures. Therefore, reaction-assisted desorption of oxygen during N2O dec omposition reaction at the low temperature was proposed. (C) 2000 Elsevier Science B.V. All rights reserved.