CO–NO reaction on Rh(110) studied using molecular beams

Abstract

The reaction between CO and NO on Rh(110) has been studied using a thermal molecular beam which can be considered to be a single-collision catalytic reactor. The reaction has been studied under transient, steady-state and pseudo-state conditions at low pressure. It is shown that NO very effectively blocks CO adsorption, in contrast to the CO–O₂ reaction, for which CO is adsorbed and reacts efficiently. Over a wide temperature range, the CO–NO reaction is slower than CO oxidation, largely owing to additional blockage of surface sites by molecular NO and atomic N. These data are compared with other work on supported catalysts, which show a much smaller rate of reaction than for Rh(111), and they indicate that it is not surface morphology which limits the reaction, [since (110) shows a higher rate than (111)], but that contamination from the catalyst preparation may possibly be the cause of the difference.