KINETICS OF OXYGEN TITRATION BY CARBON-MONOXIDE ON RHODIUM

Data for the low pressure transient kinetics of oxygen titration by carbon monoxide on polycrystalline Rh are reported for temperatures between 360 and 779 K. The time dependence of CO pressure and CO2 evolution are followed when a constant flux of CO is introduced onto a Rh wire predosed in oxygen. The results of a variety of simulations are compared with these experimental transients and it is shown that all the data are satisfactorily accounted for by a complex Langmuir-Hinshelwood reaction path. The model involves three features: (1) an activation energy which depends on oxygen coverage below 529 K, (2) the inhibition of CO adsorption by oxygen coverage above 529 K, and (3) a drastic increase in the activation energy around 529 K. © 1979 American Chemical Society.